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1.	Belavy, D. L., et al. (författare) Characterization of Intervertebral Disc Changes in Asymptomatic Individuals with Distinct Physical Activity Histories Using Three Different Quantitative MRI Techniques 2020 Ingår i: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 9:6 Tidskriftsartikel (refereegranskat)abstract (1) Background: Assessments of intervertebral disc (IVD) changes, and IVD tissue adaptations due to physical activity, for example, remains challenging. Newer magnetic resonance imaging techniques can quantify detailed features of the IVD, where T2-mapping and T2-weighted (T2w) and Dixon imaging are potential candidates. Yet, their relative utility has not been examined. The performances of these techniques were investigated to characterize IVD differences in asymptomatic individuals with distinct physical activity histories. (2) Methods: In total, 101 participants (54 women) aged 25-35 years with distinct physical activity histories but without histories of spinal disease were included. T11/12 to L5/S1 IVDs were examined with sagittal T2-mapping, T2w and Dixon imaging. (3) Results: T2-mapping differentiated Pfirrmann grade-1 from all other grades (p< 0.001). Most importantly, T2-mapping was able to characterize IVD differences in individuals with different training histories (p< 0.005). Dixon displayed weak correlations with the Pfirrmann scale, but presented significantly higher water content in the IVDs of the long-distance runners (p< 0.005). (4) Conclusions: Findings suggested that T2-mapping best reflects IVD differences in asymptomatic individuals with distinct physical activity histories changes. Dixon characterized new aspects of IVD, probably associated with IVD hypertrophy. This complementary information may help us to better understand the biological function of the disc.
2.	Cetinic, I., et al. (författare) Ultrasound Shear Wave Elastography, Shear Wave Dispersion and Attenuation Imaging of Pediatric Liver Disease with Histological Correlation 2022 Ingår i: Children. - : MDPI AG. - 2227-9067. ; 9:5 Tidskriftsartikel (refereegranskat)abstract Aim: To evaluate the feasibility of multiple ultrasound markers for the non-invasive characterization of fibrosis, inflammation and steatosis in the liver in pediatric patients. Materials and methods: The quantitative ultrasound measures shear wave elastography (SWE), shear wave dispersion (SWD) and attenuation imaging (ATI) were compared and correlated with percutaneous liver biopsies and corresponding measures in a control cohort. Results: The median age of the 32 patients was 12.1 years (range 0.1-17.9), and that of the 15 controls was 11.8 years (range: 2.6-16.6). Results: There was a significant difference in SWE values between histologic grades of fibrosis (p = 0.003), with a positive correlation according to the grade (r = 0.7; p < 0.0001). Overall, a difference in SWD values between grades of inflammation was found (p = 0.009) but with a lack of correlation (r = 0.1; p = 0.67). Comparing inflammation grades 0-1 (median:13.6 m/s kHz [min; max; 8.4; 17.5]) versus grades 2-3 (16.3 m/s kHz [14.6; 24.2]) showed significant differences between the groups (p = 0.003). In the 30 individuals with a steatosis score of 0, ATI was measured in 23 cases with a median value of 0.56 dB/cm/MHz. Conclusion: Comprehensive ultrasound analysis was feasible to apply in children and has the potential to reflect the various components of liver affection non-invasively. Larger studies are necessary to conclude to what extent these image-based markers can classify the grade of fibrosis, inflammation and steatosis.
3.	Hebelka, Hanna, 1977, et al. (författare) Lumbar vertebral T2-relaxation time investigated with T2-mapping at multiple time points in a day demonstrate large individual variations 2022 Ingår i: Diagnostic and Interventional Radiology. - : Galenos Yayinevi. - 1305-3825. ; 28:1, s. 92-97 Tidskriftsartikel (refereegranskat)abstract PURPOSE The increasing interest of endplate and Modic changes as potential pain generators in low back pain (LBP), along with advancement of functional quantitative magnetic resonance imaging (MRI) techniques, makes it important to characterize the vertebral dynamic behavior in detail. This study aims to perform characterization of the dynamic behavior of the vertebral bodies (VB) by investigating the VB diurnal variation in T2-relaxation time in a cross-sectional asymptomatic group of individuals. METHODS T2-mapping of 30 VBs (L1-L5) in six healthy volunteers (mean age, 40 years; range, 29-65 years) was performed with a 1.5 Tesla MRI at three time points over the day (7 am, 12 am, 5 pm). Volumetric regions of interest were segmented manually to determine VB T2-relaxation time, which was compared between the three time points. RESULTS On a group level only small and not significant diurnal VB variation was detected (all P >.10), with median T2 (ms) (quartiles; Q1, Q3) at the three time points 88.7 (84.1, 99.1), 87.3 (85.0, 96.1) and 87.8 (84.4, 99.2). However, in some VBs up to 7% increase respectively 9% decrease in T2-relaxation time was found during the day. Further, there was a relatively large variation between the individuals in absolute VB T2-relaxation times (range 73.2-108.3 ms), but small differences between the VBs within an individual. CONCLUSION This first T2-mapping study of the VB signal dynamics, in repeated investigations during one day, display variation in T2-relaxation time in specific individual VBs but were negligible on a group level. The result may be of importance when evaluating patients with spinal pathologies and suggest further examinations of dynamic changes not only of the disc but also vertebrae. © Turkish Society of Radiology 2021.
4.	Rasmussen, A. M., et al. (författare) Repeatability of diffusion-based stiffness prediction – A healthy volunteer study 2024 Ingår i: Radiography. - 1078-8174 .- 1532-2831. ; 30:2, s. 524-530 Tidskriftsartikel (refereegranskat)abstract Introduction: The study investigated the repeatability of brain diffusion-based stiffness prediction (DWIstiff) in healthy volunteers. Methods: Thirty-one healthy volunteers were examined with DWIstiff using two different sets of b-values: b200-1500 s/mm2 (DWIstiff, 1500) and b200-1000 s/mm2 (DWIstiff, 1000). Each b-value set was scanned twice per imaging session without repositioning the participants. DWIstiff images were reconstructed from each set. Two observers delineated regions of interest (ROIs) on each DWIstiff image. The repeatability coefficient (RC), coefficient of variation (CV), inter- and intraobserver agreement were calculated. Results: After excluding three participants due to image artifacts, the study included twenty-eight volunteers (mean age (range)) 37 years (24–62), 10 males, 18 females). For DWIstiff, 1500, the lowest and the highest RCs were in the parietal lobe (0.52) and respectively the brain stem (1.17). The lowest RC for DWIstiff, 1000 was in the frontal lobe (0.42) and the highest in the brain stem (1.58). The CV for whole brain measurements was 3.83 % for DWIstiff, 1500 and 4.93 % for DWIstiff, 1000. The Bland‒Altman (BA) limits of agreement (LoA) for the intraobserver agreement of DWIstiff, 1500 were −0.90 to 1.06 and respectively −0.78 to 0.88 for DWIstiff, 1000. Regarding interobserver agreement, the LoA were −0.85 to 0.94 for DWIstiff, 1500 and −0.61 to 0.66 for DWIstiff, 1000. Conclusion: DWIstiff is a precise technique with some observer dependence. Repeatability is higher for DWIstiff, 1000 s/mm2 than for DWIstiff 1500 s/mm2. Implications for practice: Our findings suggest that DWIstiff can reliably detect stiffness changes larger than 4.93 % in healthy volunteers. Further studies should investigate whether the repeatability of DWIstiff may be affected by the presence of pathology such as a brain tumor.
5.	Agerskov, Simon, et al. (författare) MRI diffusion and perfusion alterations in the mesencephalon and pons as markers of disease and symptom reversibility in idiopathic normal pressure hydrocephalus 2020 Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:10 Tidskriftsartikel (refereegranskat)abstract Introduction Core symptomatology in idiopathic normal pressure hydrocephalus (iNPH) points at dysfunction in the mesencephalon and pons indicating pathological changes in these regions, but only a few studies have addressed the issue. The aim of this study was to investigate diffusion (ADC) and perfusion patterns pre- and postoperatively in these areas in iNPH. Methods Twenty iNPH patients and 15 healthy controls were included. Patients underwent a clinical examination and brain MRI pre- and 3-6 months postoperatively. The MRI-scan included diffusion and dynamic susceptibility contrast perfusion weighted sequences. Regions of interest in the mesencephalon and pons were drawn on a FLAIR sequence and co-registered to ADC maps and perfusion data. Results There were no significant differences in pre or postoperative ADC compared to the control group, however postoperative ADC increased by 10% (p = 0.026) in the mesencephalon and 6% (p = 0.016) in the pons in all patients and also in the subgroup of shunt responders by 11% (p = 0.021) and 4% (p = 0.020), respectively. Preoperative relative cerebral blood flow (rCBF) was similar in iNPH patients and controls. Postoperatively, rCBF increased in shunt responders by 6% (p = 0.02) in the mesencephalon and 11% (p = 0.004) in the pons. This increase correlated with the degree of clinical improvement (r(s)= 0.80, p = 0.031 and r(s)= 0.66, p = 0.021, respectively). Conclusion The postoperative increase in ADC and the correlation between postoperative increase in rCBF and clinical improvement in the mesencephalon and pons shown in this study point at an involvement of these areas in the core pathophysiology and its reversibility in iNPH.
6.	Arvidsson, Jonathan, et al. (författare) Arterial occlusion duration affects the cuff-induced hyperemic response in skeletal muscle BOLD perfusion imaging as shown in young healthy subjects 2023 Ingår i: Magnetic Resonance Materials in Physics Biology and Medicine. - 1352-8661. ; 36:6, s. 897-910 Tidskriftsartikel (refereegranskat)abstract Objective Dynamic BOLD MRI with cuff compression, inducing ischemia and post-occlusive hyperemia in skeletal mus-cle, has been pointed out as a potential diagnostic tool to assess peripheral limb perfusion. The objective was to explore the robustness of this technique and its sensitivity to the occlusion duration. Materials and methods BOLD images were acquired at 3 T in 14 healthy volunteers. T2-imaging with 5-and 1.5-min occlu-sions were acquired and several semi-quantitative BOLD parameters were derived from ROI-based T2-time curves. Differ-ences in parameters from the two different occlusion durations were evaluated in the gastrocnemius and soleus muscles using non-parametrical tests. Intra-and inter-scan repeatability were evaluated with coefficient of variation.Results Longer occlusion duration resulted in an increased hyperemic signal effect yielding significantly different values (p < 0.05) in gastrocnemius for all parameters describing the hyperemic response, and in soleus for two of these parameters. Specifically, 5-min occlusion yielded steeper hyperemic upslope in gastrocnemius (41.0%; p < 0.05) and soleus (59.7%; p = 0.03), shorter time to half peak in gastrocnemius (46.9%; p = 0.00008) and soleus (33.5%; p = 0.0003), and shorter time to peak in gastrocnemius (13.5%; p = 0.02). Coefficients of variation were lower than percentage differences that were found significant. Discussion Findings show that the occlusion duration indeed influences the hyperemic response and thus should play a part in future methodological developments.
7.	Arvidsson, Jonathan, et al. (författare) Effects of bolus injection duration on perfusion estimates in dynamic CT and dynamic susceptibility contrast MRI 2023 Ingår i: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer Science and Business Media LLC. - 0968-5243 .- 1352-8661. ; 36:1, s. 95-106 Tidskriftsartikel (refereegranskat)abstract Estimates of cerebral blood flow (CBF) and tissue mean transit time (MTT) have been shown to differ between dynamic CT perfusion (CTP) and dynamic susceptibility contrast MRI (DSC-MRI). This study investigates whether these discrepancies regarding CBF and MTT between CTP and DSC-MRI can be attributed to the different injection durations of these techniques. Five subjects were scanned using CTP and DSC-MRI. Region-wise estimates of CBF, MTT, and cerebral blood volume (CBV) were derived based on oscillatory index regularized singular value decomposition. A parametric model that reproduced the shape of measured time curves and characteristics of resulting perfusion parameter estimates was developed and used to simulate data with injection durations typical for CTP and DSC-MRI for a clinically relevant set of perfusion scenarios and noise levels. In simulations, estimates of CBF/MTT showed larger negative/positive bias and increasing variability for CTP when compared to DSC-MRI, especially for high CBF levels. While noise also affected estimates, at clinically relevant levels, the injection duration effect was larger. There are several methodological differences between CTP and DSC-MRI. The results of this study suggest that the injection duration is among those that can explain differences in estimates of CBF and MTT between these bolus tracking techniques.
8.	Cetinic, Ivan, et al. (författare) Shear wave elastography and shear wave dispersion correlated to biopsy at the scheduled follow-up of pediatric liver grafts 2023 Ingår i: Pediatric Transplantation. - 1397-3142. ; 27:7 Tidskriftsartikel (refereegranskat)abstract Background: It is unknown how shear wave dispersion (SWD) is displayed in pediatric liver transplant recipients and not fully elucidated how ultrasound shear wave elastography (2D-SWE) display within this cohort, which is important to determine to improve noninvasive surveillance of these patients. The study aimed to compare SWE and SWD values with histopathology in pediatric liver recipients.Methods: Forty-eight pediatric liver recipients were examined with SWE in conjunction with an elective liver biopsy (clinically without complication). Additionally, SWD values were measured in 21 children. SWE and SWD values were compared to histologically determined fibrosis graded as none-to-mild (F0-1) and moderate-to-severe (F2-4), and inflammation graded as low (grade 0-1) and high (grade 2-4).Results: Two children were excluded due to SWE IQR/median > 30% kPa. The mean age across 46 included patients was 10.9 years (range 1.4-18). The number of patients and median (range) SWE value (kPa) for each stage of fibrosis were: F0-1 [n = 23; 5.8 (3.2-16.1)], F2 [n = 22; 6.0 (4.5-25.9)], F3 [n = 1; 33.3], and F4 [n = 0]. Significantly higher SWE values and greater variability were registered in F2-4 vs. F0-1 (p = .05). Grade of fibrosis correlated weakly to SWE values (r = .3; p = .05), but not to SWD values (r = .2; p = .27). In patients with low-grade inflammation, median SWD was 13.7 m/s KHz (10.7-17.6). Only one patient had high-grade inflammation.Conclusions: Uncomplicated transplanted liver grafts in a small pediatric cohort revealed slightly increased SWE and SWD values compared to previously reported values in healthy children. This likely reflect both the fibrotic and inflammatory elements in the grafts; however, other confounders impacting the liver's viscoelastic properties are also probable factors.
9.	Eriksson, Stefanie, et al. (författare) Texture Analysis of Magnetic Resonance Images Enables Phenotyping of Potentially Painful Annular Fissures. 2022 Ingår i: Spine. - 1528-1159. ; 47:5, s. 430-437 Tidskriftsartikel (refereegranskat)abstract Retrospective analysis of prospectively collected data.To investigate whether intervertebral disc (IVD) image features, extracted from magnetic resonance (MR) images, can depict the extension and width of annular fissures and associate them to pain.Annular fissures are suggested to be associated with low back pain (LBP). Magnetic resonance imaging (MRI) is a sensitive method, yet fissures are sometimes unobservable in T2-weighted MR-images, even though fissure information is present in the image. Image features can mathematically be calculated from MR-images and might reveal fissure characteristics.44 LBP patients who underwent MRI, low-pressure discography (<50psi) and computed tomography (CT) sequentially in one day, were reviewed. After semi-automated segmentation of 126 discs, image features were extracted from the T2-weighted images. The number of image features were reduced with principle component analysis (PCA). CT-discograms were graded and dichotomized regarding extension and width of fissures. IVDs were divided into fissures extending to outer annulus vs. short/no fissures. Fissure width was dichotomized into narrow (<10%) vs. broad fissures (>10%), and into moderately broad (10%-50%) vs. very broad fissures (>50%). Logistic regression was performed to investigate if image features could depict fissure extension to outer annulus and fissure width. As a sub-analysis, the association between image features used to depict fissure characteristics and discography-provoked pain-response were investigated.Fissure extension could be depicted with sensitivity/specificity=0.97/0.77 and area under curve (AUC)=0.97. Corresponding results for width depiction were sensitivity/specificity=0.94/0.39 and 0.85/0.62, and AUC=0.86 and 0.81 for narrow vs. broad and moderately broad vs. very broad fissures respectively. Pain prediction with image features used for depicting fissure characteristics showed sensitivity/specificity=0.90/0.36, 0.88/0.4, 0.93/0.33; AUC=0.69, 0.75 and 0.73 respectively.Standard MR-images contains fissure information associated to pain that can be depicted with image features, enabling non-invasive phenotyping of potentially painful annular fissures.Level of Evidence: 2.
10.	Flehr, Alison, et al. (författare) Development of a novel method to measure bone marrow fat fraction in older women using high-resolution peripheral quantitative computed tomography 2022 Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 33:7, s. 1545-1556 Tidskriftsartikel (refereegranskat)abstract Bone marrow adipose tissue (BMAT) has been implicated in a number of conditions associated with bone deterioration and osteoporosis. Several studies have found an inverse relationship between BMAT and bone mineral density (BMD), and higher levels of BMAT in those with prevalent fracture. Magnetic resonance imaging (MRI) is the gold standard for measuring BMAT, but its use is limited by high costs and low availability. We hypothesized that BMAT could also be accurately quantified using high-resolution peripheral quantitative computed tomography (HR-pQCT). Methods: In the present study, a novel method to quantify the tibia bone marrow fat fraction, defined by MRI, using HR-pQCT was developed. In total, 38 postmenopausal women (mean [standard deviation] age 75.9 [3.1] years) were included and measured at the same site at the distal (n = 38) and ultradistal (n = 18) tibia using both MRI and HR-pQCT. To adjust for partial volume effects, the HR-pQCT images underwent 0 to 10 layers of voxel peeling to remove voxels adjacent to the bone. Linear regression equations were then tested for different degrees of voxel peeling, using the MRI-derived fat fractions as the dependent variable and the HR-pQCT-derived radiodensity as the independent variables. Results: The most optimal HR-pQCT derived model, which applied a minimum of 4 layers of peeled voxel and with more than 1% remaining marrow volume, was able to explain 76% of the variation in the ultradistal tibia bone marrow fat fraction, measured with MRI (p < 0.001). Conclusion: The novel HR-pQCT method, developed to estimate BMAT, was able to explain a substantial part of the variation in the bone marrow fat fraction and can be used in future studies investigating the role of BMAT in osteoporosis and fracture prediction.
11.	Gao, Sinsia, 1966, et al. (författare) The usefulness of left ventricular volume and aortic diastolic flow reversal for grading chronic aortic regurgitation severity-Using cardiovascular magnetic resonance as reference 2021 Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273. ; 340, s. 59-65 Tidskriftsartikel (refereegranskat)abstract Echocardiographic evaluation of chronic aortic regurgitation (AR) severity can lead to diagnostic ambiguity due to few feasible parameters or incongruent findings. The aim of the present study was to improve the diagnostic usefulness of left ventricular (LV) enlargement and aortic end-diastolic flow velocity (EDFV) using cardiovascular magnetic resonance (CMR) as reference. Patients (n = 120) were recruited either prospectively (n = 45) or retrospectively (n = 75). Severe AR (CMR regurgitant fraction 75/87 ml/m2) were identified using ROC analyses in the derivation group. The corresponding thresholds for EDFV were 10 cm/s. In the test group, the positive/negative likelihood ratios to rule in/rule out severe AR using EDVI were 10.0/0.14 (traditional), 6.2/0.11 (recommended), and using EDFV were 10.2/0.08. To rule in and rule out severe AR using derived cut-off values instead of 2 SD reduced the false positives by 92%, whereas using EDFV <10 cm/s instead of <20 cm/s reduced the false negatives by 94%. In conclusion, EDVI and EDFV as quantitative parameters are useful to rule in or rule out severe chronic AR. Importantly, other causes of LV enlargement have to be considered.
12.	Hebelka, Hanna, 1977, et al. (författare) Axial Loading during MRI Induces Lumbar Foraminal Area Changes and Has the Potential to Improve Diagnostics of Nerve Root Compromise 2022 Ingår i: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 11:8 Tidskriftsartikel (refereegranskat)abstract Lumbar foraminal stenosis is a common cause of lumbar radiculopathy and conventionally assessed with magnetic resonance imaging (MRI) in supine-positioned patients. An MRI acquired during spine loading may unmask pathology not otherwise revealed in a relaxed position. Therefore, we investigated how spine loading during MRI affects lumbar foramina. In 89 low-back pain patients’ lumbar, MRIs were performed in a relaxed supine position and during axial loading using a Dynawell® compression device. The smallest area of all intervertebral foramina at levels L3/L4–L5/S1 (534 foramina) was determined using a freehand polygonal tool in parasagittal T2-weighted sequences. The grading system described by Lee et al. was also used to qualitatively assess foraminal stenosis. Overall, a mean reduction of 2.2% (mean −0.89 cm2 and −0.87 cm2, respectively) was observed (p = 0.002), however for individual foramina large variations, with up to about 50% increase or decrease, were seen. Stratified for lumbar level, an area reduction was found for L3/L4 and L4/L5 foramina (mean change −0.03 cm2; p = 0.036; and −0.03 cm2; p = 0.004, respectively) but not for L5/S1. When comparing the measured area changes to qualitative foraminal grading, 22% of the foramina with a measured area decrease were evaluated with a higher grading. Thus, detailed information on foraminal appearance and nerve root affection can be obtained using this method.
13.	Hebelka, Hanna, 1977, et al. (författare) Clinical outcome and MRI appearance in a group of chronic low back pain patients more than 10 years after discography evaluation and consideration for surgery 2023 Ingår i: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 24:1 Tidskriftsartikel (refereegranskat)abstract BackgroundIt is an ongoing debate whether fusion surgery is superior to non-operative treatment for non-specific low back pain (LBP) in terms of patient outcome. Further, the evidence for how signs of intervertebral disc (IVD) degeneration on magnetic resonance imaging (MRI) correlate with patient outcome is insufficient. Longitudinal studies of low back pain (LBP) patients are thus of interest for increased knowledge. The aim of this study was to investigate long-term MRI appearance in LBP patients 11-14 years after discography.MethodsIn 2021, 30 LBP patients who had same-day discography and MRI in 2007-2010 were asked to undergo MRI (Th12/L1-L5/S1), complete visual analog scale (VAS), Oswestry Disability Index (ODI) and EuroQol-5 Dimension (EQ5D) questionnaires. Patients who had fusion surgery before the follow-up were compared with those without such surgery. MRIs were evaluated on Pfirrmann grade, endplate classification score (EPS), and High Intensity Zones (HIZ). For each disk it was noted if injected at baseline or not.ResultsOf 17 participants (6 male;mean age 58.5 years, range 49-72), 10 (27 disks) had undergone fusion surgery before the follow-up. No differences in VAS, ODI, or EQ5D scores were found between patients with and without surgery (mean 51/32/0.54 vs. 50/37/0.40, respectively; 0.77 > p < 0.65). Other than more segments with EPS >= 4 in the surgery group (p < 0.05), no between-group differences were found in longitudinal change in MRI parameters. Of 75 non-fused disks, 30 were injected at baseline. Differences were found between injected and non-injected disks at both baseline and follow-up for Pfirrmann grade and HIZ, and at follow-up for EPS (0.04 > p < 0.001), but none for progression over time (0.09 > p < 0.82).ConclusionsOther than more endplate changes in the surgery group, no differences in longitudinal change of MRI parameters were established between LBP patients treated with or without fusion surgery in the studied cohort. The study also highlights the limited progress of degenerative changes, which may be seen over a decade, despite needle puncture and chronic LBP.
14.	Hebelka, Hanna, 1977, et al. (författare) Coexistence of Vertebral and Intervertebral Disc Changes in Low Back Pain Patients—In Depth Characterization with Same Day MRI and CT Discography 2023 Ingår i: Diagnostics. - 2075-4418. ; 13:23 Tidskriftsartikel (refereegranskat)abstract The aim of this study was to investigate to what extent annular fissures, vertebral and endplate changes, and Modic changes (MCs), coexist in low back pain (LBP) patients by using multiple imaging modalities. Sixty-two LBP patients (mean age 45 years, range 24–63, 53% men) were examined with same-day CT-discography and MRI. Intervertebral discs punctured for discography (n = 204) were evaluated on MRI [Pfirrmann grade, High-Intensity Zone (HIZ)] and on CT-discograms [Modified Dallas Discogram Score (DDS)]. DDS≥ 1, i.e., disc fissures involving the outer annulus were further digitomized into delimitable fissuring (<50% of annulus affected) or non-delimitable annular fissuring. Using both MRI and CT, adjacent vertebrae and endplates were assessed for MC, vertebral sclerosis, and a modified endplate defect score (EPS). In 194 discs the contrast agent was adequately injected during discography, of which 160 (83%) displayed outer annular fissures, with 91 (47%) of the latter being delimitable fissures. Most discs with delimitable fissures were moderately degenerated; 68% Pfirrmann grade ≤3, 71% EPS ≤ 2, and 12% displayed MC. The majority (76%) of MCs were associated with advanced adjacent disc degeneration; 84% Pfirrmann grade ≥4, 76% with non-delimitable annular fissuring, 59% EPS≥ 4, and 34% EPS of 3. A total 95 HIZ (47%) were found, of which 54 had delimitable fissuring, while the remainder displayed non-delimitable fissuring. Vertebral sclerosis was commonly observed (26%), both with MCs (73%) and without MCs (27%), and not specifically linked to MC type 3. A total of 97% of segments with vertebral sclerosis displayed outer annular fissures. These findings were significant (0.046 > p > 0.0001), except between HIZ and adjacent sclerosis (p = 0.303). To conclude, the present study confirmed a close interplay between the disc and adjacent vertebra and endplates. The fact that a majority of discs with delimitable annular fissures did not coexist with pronounced endplate changes and/or MCs, however, supports the theory that disc fissuring is an early event in the degenerative cascade. This was further supported by the fact that MCs were strongly linked to extensive disc fissuring and to advanced endplate damage. Further, vertebral sclerosis was common also in vertebra without MCs and strongly associated to annular fissuring, indicating that sclerosis is a previously underestimated feature of a general degenerative process.
15.	Hebelka, Hanna, 1977, et al. (författare) Loading of the Spine in Low Back Pain Patients Does Not Induce MRI Changes in Modic Lesions: A Prospective Clinical Study 2022 Ingår i: Diagnostics (Basel). - : MDPI AG. - 2075-4418. ; 12:8 Tidskriftsartikel (refereegranskat)abstract Modic changes (MCs) are gaining increased interest as potential generators of low back pain (LBP). The current aim was to investigate possible spinal loading effects on the MRI signal in MCs in patients with LBP. Supine lumbar MRIs were performed and immediately repeated with axial loading in 100 LBP patients. A total of 43 patients (23 male, mean age 45.7 years) had MCs. Each Modic was outlined on all sagittal T2-weighted images (>25% affected vertebrae). For reference, regions of interest were placed in both vertebrae without Modic and in Modic-free tissue in vertebrae with Modic. The Modic signal intensity, normalized to cerebrospinal fluid, and Modic volume were compared between MRIs with and without spinal loading. Of the 94 MCs, 36.2% (n = 34) were type I, 58.5% (n = 55) were type II, and 5.3% (n = 5) were type III. No differences in Modic volume (mean 0.046 cm3; p = 0.25) between the MRIs with and without spinal loading were found. In addition, no significant changes in Modic signal were induced by loading (mean 1.5% difference; p = 0.308). Loading increased the signal in the reference regions of interest in vertebrae both with Modic (mean 5.5%; p = 0.002) and without (mean 3.5%; SD 0.09; p = 0.02). To conclude, MRIs performed with and without spinal loading showed no change in either volume or signal of MCs, suggesting that most MCs are not instantaneously influenced by biomechanical load.
16.	Hebelka, Hanna, 1977, et al. (författare) Shear Wave Elastography in the Differentiation of Nonfibrotic Versus Fibrotic Liver Disease in Children: A Prospective Study With Histological Correlation 2021 Ingår i: Journal of Pediatric Gastroenterology and Nutrition Reports - JPGN Reports. - 1536-4801. ; 3:1 Tidskriftsartikel (refereegranskat)
17.	Hedelin, Henrik, 1975, et al. (författare) Postoperative stability following a triple pelvic osteotomy is affected by implant configuration: a finite element analysis 2022 Ingår i: Journal of Orthopaedic Surgery and Research. - : Springer Science and Business Media LLC. - 1749-799X. ; 17:1 Tidskriftsartikel (refereegranskat)abstract Background The triple pelvic osteotomy is an established surgical method with multiple modifications regarding surgical technique and choice of implant. The stability of the osteotomy is affected by numerous factors, and among these, the three-dimensional implant configuration is a scientifically less explored aspect. Methods We used a finite element model of a hemi-pelvis with a standardized triple osteotomy to calculate relative flexibility for loads in all translational degrees of freedom for five different implant configurations. Two of the configurations used entry points only feasible when implant removal was not necessary. Results The stability of the osteotomy improved with an increased distance between the implants in the plane of the osteotomy as well as for a more perpendicular angle relative to the osteotomy plane. The implant configurations with more entry points available made this easier to adhere to. Conclusion The use of bioabsorbable implants may provide better opportunities for optimal implant constructs which can, to a certain degree, compensate for the lesser mechanical stiffness of bioabsorbable polymers as compared to metal implants.
18.	Hedelin, Henrik, 1975, et al. (författare) Stability in Pelvic Triple Osteotomies in Children Using Resorbable PLGA Screws for Fixation 2021 Ingår i: Journal of Pediatric Orthopaedics. - : Ovid Technologies (Wolters Kluwer Health). - 0271-6798. ; 41:9 Tidskriftsartikel (refereegranskat)abstract Background: The triple pelvic osteotomy (TPO) is a major redirectional osteotomy used to improve the acetabular coverage of the femoral head in selected pediatric patients with hip disorders. Traditionally the iliac osteotomy is stabilized by metal screws that require a second surgery for removal. Despite favorable results for both adults and children in related pelvic osteotomies, resorbable implants have not previously been used for TPOs. This study aims to suggest a novel modified TPO surgical method in children using resorbable poly lactic-co-glycolic acid (PLGA) screws for fixation and to radiographically evaluate the postoperative stability achieved by these implants in a case series. Methods: All patients (n=11) with dysplasia of the hip (2), Perthe disease (5), or Down syndrome (4), who underwent primary TPO surgery during 2013 to 2019, using resorbable PLGA screws for fixation were included. The stability of the osteotomy was evaluated in the postoperative radiograph series using the acetabular index, migration percentage, Sharp's angle and the center-edge angle. The osteotomy angle was introduced as a parameter to confirm the postoperative integrity of the achieved correction. All cases were evaluated until radiographic healing of the iliac osteotomy. Hospital notes were analyzed for complications or local reactions in relation to the implants. Results: In all studied hips, the overall achieved correction was well maintained. The mean (SD) correction achieved, from the preoperative images to the last measurable postoperative image, was a 16.7 degrees decrease for Sharp angle, a 20.9 degrees decrease in acetabular index and a 24.7 degrees increase for the center-edge angle, respectively. There were no complications related to the bioabsorption of the implants. Conclusion: The present findings suggest that the modified TPO method, using resorbable PLGA screws, provides sufficient stability and appears to be a promising alternative to traditional TPO. Avoiding implant removal is a major benefit in a pediatric population. Resorbable screws enable the surgeon to place implants with more degrees of freedom since later implant removal is not a limiting factor.
19.	Hutchins, John, et al. (författare) A systematic review of validated classification systems for cervical and lumbar spinal foraminal stenosis based on magnetic resonance imaging. 2022 Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 1432-0932 .- 0940-6719. ; 31:6, s. 1358-1369 Tidskriftsartikel (refereegranskat)abstract Foraminal stenosis is commonly investigated with radiological methods in patients with radiating pain in extremities. However, there is a lack of consensus regarding the methodology to assess compression of the nerve roots. This systematic review was performed to identify validated classification systems for foraminal stenosis in the lumbar and cervical spine based on magnetic resonance imaging (MRI).A systematic search was conducted according to the PRISMA guidelines. The search included Cochrane, Embase, Medline and PubMed databases going back 30years and up to September 2021. Three categories of words were used in different variations; foraminal stenosis, MRI and scoring. For inclusion, at least one word from each category had to be present. Articles suggesting classification systems or reporting on their validation were selected for inclusion.A total of 823 articles were identified and all abstracts were reviewed. Subsequently, a full-text review of 64 articles was performed and finally 14 articles were included. A total of three validated classification systems were found for the cervical and lumbar spine. The remaining 11 articles reported on validation or suggested modifications of the classification systems.The three classification systems demonstrated moderate to good reliability and have all been shown feasible in the clinical setting. There is however a need for further studies testing the validity of these classifications in relation to both clinical findings and to surgical outcome data.
20.	Hutchins, John, et al. (författare) Cervical Foraminal Changes in Patients with Intermittent Arm Radiculopathy Studied with a New MRI-Compatible Compression Device 2023 Ingår i: Journal of Clinical Medicine. - 2077-0383. ; 12:20 Tidskriftsartikel (refereegranskat)abstract Diagnosing cervical foraminal stenosis with intermittent arm radiculopathy is challenging due to discrepancies between MRI findings and symptoms. This can be attributed to the fact that MRI images are often obtained in a relaxed supine position. This study aims to evaluate the feasibility of the Dynamic MRI Compression System (DMRICS) and to assess possible changes in cervical foramina, with both quantitative measurements and qualitative grading systems, with MRI during a simulated Spurling test. Ten patients (five women and five men, ages 29-45) with previously confirmed cervical foraminal stenosis underwent MRI scans using DMRICS. MRI images were acquired in both relaxed and provoked states. A radiologist assessed 30 foramina (C4-C7) on the symptomatic side in both patient positions. Quantitative and qualitative measures were performed, including the numeric rating scale (NRS) and the Park and Kim grading systems. The provoked state induced concordant neck and arm pain in 9 of 10 patients. Significant shifts in Park and Kim foraminal gradings were noted: 13 of 27 Park gradings and 9 of 27 Kim gradings escalated post provocation. No quantitative changes were observed. This pilot study indicates that the DMRICS device has the potential to improve diagnostic accuracy for cervical radiculopathy, demonstrating induced cervical foraminal changes during a simulated Spurling test while performing MRI.
21.	Hutchins, John, et al. (författare) MRI evaluation of foraminal changes in the cervical spine with assistance of a novel compression device 2023 Ingår i: Scientific Reports. - 2045-2322. ; 13:1 Tidskriftsartikel (refereegranskat)abstract Standard supine Magnetic Resonance Imaging (MRI) does not acquire images in a position where most patients with intermittent arm radiculopathy have symptoms. The aim of this study was to test the feasibility of a new compression device and to evaluate image quality and foraminal properties during a Spurling test under MRI acquisition. Ten asymptomatic individuals were included in the study (6 men and 4 women; age range 27 to 55 years). First, the subjects were positioned in the cervical compression device in a 3 T MRI scanner, and a volume T2 weighted (T2w) sequence was acquired in a relaxed supine position (3 min). Thereafter, the position and compressive forces on the patient's neck (provocation position) were changed by maneuvering the device from the control room, with the aim to simulate a Spurling test, causing a mild foraminal compression, followed by a repeated image acquisition (3 min). A radiologist measured the blinded investigations evaluating cervical lordosis (C3-C7), foraminal area on oblique sagittal images and foraminal cross-distance in the axial plane. A total of three levels (C4-C7) were measured on the right side on each individual. Measurements were compared between the compressed and relaxed state. Reliability tests for inter- and intraclass correlation were performed. The device was feasible to use and well tolerated by all investigated individuals. Images of adequate quality was obtained in all patients. A significant increase (mean 9.4, p = 0.013) in the cervical lordosis and a decreased foraminal cross-distance (mean 32%, p < 0.001) was found, during the simulated Spurling test. The area change on oblique sagittal images did not reach a statistically significant change. The reliability tests on the quantitative measures demonstrated excellent intraobserver reliability and moderate to good interobserver reliability. Applying an individualized provocation test on the cervical spine, which simulates a Spurling test, during MRI acquisition was feasible with the novel device and provided images of satisfactory quality. MRI images acquired with and without compression showed changes in cervical lordosis and foraminal cross distance indicating the possibility of detecting changes of the foraminal properties. As a next step, the method is to be tested on symptomatic patients.
22.	Identeg, Fredrik, 1990, et al. (författare) Low occurrence of MRI spinal changes in elite climbing athletes; a cross-sectional study. 2023 Ingår i: BMC sports science, medicine & rehabilitation. - : Springer Science and Business Media LLC. - 2052-1847. ; 15:1 Tidskriftsartikel (refereegranskat)abstract To examine the occurrence of magnetic resonance imaging (MRI) changes in the thoracolumbar spine among elite climbing athletes.All climbers of the Swedish national sport climbing team (n=8), and individuals having trained for selection to the national team (n=11), were prospectively included. A control group, matched in age and sex, were recruited. All participants underwent a thoracolumbar MRI (1.5T, T1- and T2-weighted imaging), evaluated according to Pfirrmann classification, modified Endplate defect score, Modic changes, apophyseal injuries and spondylolisthesis. Pfirrmann≥3, Endplate defect score≥2 and Modic≥1 was defined as degenerative findings.Fifteen individuals, 8 women, participated in both the climbing group (mean age 23.1, SD 3.2years) and the control group respectively (mean age 24.3, SD 1.5years). In the climbing group, 6.1% of the thoracic and 10.6% of the lumbar intervertebral discs showed signs of degeneration according to Pfirrmann. One disc with a grade above 3 was present. Modic changes in the thoracic/lumbar spine were prevalent in 1.7%/1.3% of the vertebrae. Degenerative endplate changes according to the Endplate defect score were found in 8.9% and 6.6% of the thoracic and lumbar spinal segments of the climbing group, respectively. Two apophyseal injuries were found, while no participants displayed signs of spondylolisthesis. There was no difference in point-prevalence of radiographic spinal changes between climbers and controls (0.07
23.	Johansson, Frida, et al. (författare) Non-Invasive Evaluation of Intradiscal Deformation during Axial Loading of the Spine Using Deformation-Field Magnetic Resonance Imaging: A Potential Tool for Micro-Instability Measurements 2022 Ingår i: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 11:16 Tidskriftsartikel (refereegranskat)abstract Degeneration alters the structural components of the disc and its mechanical behavior. Understanding this pathophysiological process is of great importance, as it may lead to back pain. However, non-invasive methods to characterize the disc mechanics in vivo are lacking. Here, a potential method for measurements of the intradiscal deformation under stress is presented. The method utilizes a standard MRI protocol, commercial loading equipment, and registration software. The lumbar spine (L1/L2-L5/S1) of 36 human subjects was imaged with and without axial loading of the spine. The resulting images were registered, and changes in the images during the registration were displayed pixel-by-pixel to visualize the internal deformation of the disc. The degeneration grade, disc height, disc angle and tilt angle were determined and correlated with the deformation using multivariate regression analysis. The largest deformation was found at the lower lumbar spine, and differences in regional behaviors between individual discs were found. Weak to moderate correlations between the deformation and different disc characteristics were found, where the degeneration grade and tilt angle were the main contributing factors. To conclude, the image-based method offers a potential tool to study the pathophysiological process of the disc.
24.	Johansson, Jens, et al. (författare) Brain diffusion MRI with multiplexed sensitivity encoding for reduced distortion in a pediatric patient population 2022 Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 0730-725X. ; 87, s. 97-103 Tidskriftsartikel (refereegranskat)abstract Background: Diffusion-weighted imaging (DWI) is a valuable tool for routine imaging of the pediatric brain. However, the commonly used single-shot (ss) echo-planar imaging (EPI) DWI sequence is prone to geometric distortions and T2*-blurring. This study aimed to investigate in a pediatric population the benefits of using multiplexed sensitivity-encoding (MUSE) without and with reversed polarity gradients (RPG) instead. Methods: This retrospective study compared image quality, geometric distortions, and diffusion values between three different approaches for DWI (ssEPI, MUSE, and RPG-MUSE) in 14 patients (median age = 4 (0.6–15) years, 11 males). Distortion levels were quantified and compared in two brain regions, i.e., the brain stem and the temporal lobes, using the Dice Coefficient and the Hausdorff Distance, with T2-weighted images as reference. Expected geometrical distortion was further evaluated by comparing the effective echo spacing between the DWI sequences. Apparent diffusion coefficient (ADC) values were determined in the genu of the corpus callosum and the optic nerves. Two raters graded overall image quality and image distortions on a Likert scale. Results: Distortion levels assessed with Dice coefficient and Hausdorff distance were significantly lower for MUSE (p < 0.05) and RPG-MUSE (p < 0.01) compared to ssEPI. No significant difference in ADC values was observed between methods. The RPG-MUSE method was graded by one rater as significantly higher in overall image quality than ssEPI (p < 0.05) and by both raters as significantly lower in levels of image distortions than both MUSE (p < 0.05) and ssEPI (p < 0.05). These results were in agreement with the reduced effective echo spacing was that was attained with MUSE and RPG-MUSE. Conclusion: For imaging of the pediatric brain, MUSE and even more so RPG-MUSE offers both improved geometric fidelity and image quality compared to ssEPI. © 2022 The Authors
25.	Johansson, Jens, et al. (författare) Improved geometric fidelity in brain DWI of pediatric patients using Multiplexed Sensitivity Encoding (MUSE) 2022 Ingår i: Annual Meeting ISMRM. Konferensbidrag (övrigt vetenskapligt/konstnärligt)
26.	Johansson, Jens, et al. (författare) Segmented accelerated multi-shot diffusion imaging combined with reverse polarity gradient (RPG) correction 2022 Ingår i: Annual Meeting ISMRM. Konferensbidrag (övrigt vetenskapligt/konstnärligt)
27.	Kaliyugarasan, Satheshkumar, et al. (författare) Multi-Center CNN-Based Spine Segmentation from T2W MRI Using Small Amounts of Data 2023 Ingår i: Proceedings - International Symposium on Biomedical Imaging. - 1945-7928 .- 1945-8452. - 9781665473583 Konferensbidrag (refereegranskat)abstract Segmentation of the spinal tissues on MRI is the basis for quantitative analyses, but time-consuming if done manually. In this work, we construct a pipeline for automatic vertebrae segmentation from T2w MRI scans, assessing performance and generalizability by external validation. Our study used 15 scans from one site (Haukeland University Hospital, HUH) and 10 scans from another (Sahlgrenska University Hospital, SUH). MRI experts manually delineated the vertebral bodies Th12-L5 on all the HUH data and a subset of six scans from SUH. We trained multiple convolutional neural networks, assessing the performance in an experimental design tailored to small-data contexts and also on external data. Our best model achieved a mean Dice score of 0.899. This is comparable to results in the literature, but our system required much less training data.
28.	Lagerstrand, Kerstin M, et al. (författare) Associations between high-intensity zones, endplate, and Modic changes and their effect on T2-mapping with and without spinal load 2021 Ingår i: Journal of Orthopaedic Research. - : Wiley. - 0736-0266 .- 1554-527X. ; 39:12, s. 2703-2710 Tidskriftsartikel (refereegranskat)abstract The purpose was to investigate if high intensity zones (HIZ), Modic (MC), and endplate changes (EPC) display different behaviors measured with quantitative magnetic resonance imaging (MRI) with and without loading of the spine and if there is a simultaneous presence of these features in the same motion segment. 130 motion segments in patients with chronic low back pain (n = 26, 25-69 year, mean 38 year, 11 males) were examined. HIZs, MCs, and EPCs (i.e., structural findings, reflecting calcifications, erosions, and fissures) were determined with standardized MRI. Different T2-values with and without loading for these features were then determined with the quantitative MRI method T2-mapping. Significantly different behaviors were found in the spinal tissues with associated HIZs, MC, and EPC (p < 0.004). HIZ (62% of patients, 1-2/patient) was associated with EPC (100% of patients, 1-7/patient) (p = 0.0003 and 0.0004 for upper and lower EPs), with an occurrence of 91% for upper and 71% for lower endplates adjacent to discs with HIZ. MC (81% of patients, 1-3/patient) were associated with EPC (p < 0.0001) with an occurrence of 87% for endplates adjacent to vertebrae with MC. The occurrence of both HIZ and MC was 43% (p = 0.0001) for upper and 29% (p = 0.003) for lower vertebrae. HIZ was associated with simultaneous presence of both MC and EPC in the same motion segment. T2-mapping was found to objectively reflect changes in the spinal tissues associated with HIZs, MC, and EPC.
29.	Lagerstrand, Kerstin M, et al. (författare) Different disc characteristics between young elite skiers with diverse training histories revealed with a novel quantitative magnetic resonance imaging method 2021 Ingår i: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 30:7, s. 2082-2089 Tidskriftsartikel (refereegranskat)abstract Purpose To evaluate if there are differences in thoraco-lumbar disc characteristics between elite skiers and non-athletic controls as well as between different types of elite skiers, with diverse training histories, using a novel quantitative MRI method. Methods The thoraco-lumbar spine of 58 elite skiers (age = 18.2 +/- 1.1 years, 30 males) and 26 normally active controls (age = 16.4 +/- 0.6 years, 9 males) was examined using T2w-MRI. Disc characteristics were compared quantitatively between groups using histogram and regional image analyses to determine delta peak and T2-values in five sub-regions. Results A statistical difference in the delta peak value was found between skiers and controls (p <0.001), reflecting higher degree of disc degeneration. The histogram analysis also revealed that the type of training determines where and to what extent the changes occur. Alpine skiers displayed lumbar changes, while mogul skiers displayed changes also in the thoracic spine. Alpine skiers with diverse training dose differed in delta peak value (p = 0.005), where skiers with highest training dose displayed less changes. Regional T2-value differences were found in skiers with divergent training histories (p <0.05), reflecting differences in disc degeneration patterns, foremost within the dorsal annulus. Conclusion Differences in quantitative disc characteristics were found not only between elite skiers and non-athletic controls but also between subgroups of elite skiers with diverse training histories. The differences in the disc measures, reflecting tissue degradation, are likely related to type and intensity of the physical training. Future studies are encouraged to explore the relation between disc functionality, training history and pain to establish adequate prevention and rehabilitation programs.
30.	Lagerstrand, Kerstin M, et al. (författare) Identification of potentially painful disc fissures in magnetic resonance images using machine-learning modelling 2022 Ingår i: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 31:3 Tidskriftsartikel (refereegranskat)abstract Purpose: It is suggested that non-specific low back pain (LBP) can be related to nerve ingrowth along granulation tissue in disc fissures, extending into the outer layers of the annulus fibrosus. Present study aimed to investigate if machine-learning modelling of magnetic resonance imaging (MRI) data can classify such fissures as well as pain, provoked by discography, with plausible accuracy and precision. Methods: The study was based on previously collected data from 30 LBP patients (age = 26–64years, 11males). Pressure-controlled discography was performed in 86 discs with pain-positive discograms, categorized as concordant pain-response at a pressure ≤ 50psi and for each patient one negative control disc. The CT-discograms were used for categorization of fissures. MRI values and standard deviations were extracted from the midsagittal part and from 5 different sub-regions of the discs. Machine-learning algorithms were trained on the extracted MRI markers to classify discs with fissures extending into the outer annulus or not, as well as to classify discs as painful or non-painful. Results: Discs with outer annular fissures were classified in MRI with very high precision (mean of 10 repeated testings: 99%) and accuracy (mean: 97%) using machine-learning modelling, but the pain model only demonstrated moderate diagnostic accuracy (mean accuracy: 69%; precision: 71%). Conclusion: The present study showed that machine-learning modelling based on MRI can classify outer annular fissures with very high diagnostic accuracy and, hence, enable individualized diagnostics. However, the model only demonstrated moderate diagnostic accuracy regarding pain that could be assigned to either a non-sufficient model or the used pain reference.
31.	Lagerstrand, Kerstin M, et al. (författare) Importance of through-plane heart motion correction for the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging 2021 Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 0730-725X. ; 84, s. 69-75 Tidskriftsartikel (refereegranskat)abstract Purpose: To elucidate the influence of through-plane heart motion on the assessment of aortic regurgitation (AR) severity using phase contrast magnetic resonance imaging (PC-MRI). Approach: A patient cohort with chronic AR (n = 34) was examined with PC-MRI. The regurgitant volume (RVol) and fraction (RFrac) were extracted from the PC-MRI data before and after through-plane heart motion correction and was then used for assessment of AR severity. Results: The flow volume errors were strongly correlated to aortic diameter (R = 0.80, p < 0.001) with median (IQR 25%;75%): 16 (14; 17) ml for diameter>40mm, compared with 9 (7; 10) ml for normal aortic size (p < 0.001). RVol and RFrac were underestimated (uncorrected:64 +/- 37 ml and 39 +/- 17%; corrected:76 +/- 37 ml and 44 +/- 15%; p < 0.001) and similar to 20% of the patients received lower severity grade without correction. Conclusion: Through-plane heart motion introduces relevant flow volume errors, especially in patients with aortic dilatation that may result in underestimation of the severity grade in patients with chronic AR.
32.	Lagerstrand, Kerstin M, et al. (författare) Reliable phase-contrast flow volume magnetic resonance measurements are feasible without adjustment of the velocity encoding parameter 2020 Ingår i: Journal of Medical Imaging. - 2329-4310 .- 2329-4302. ; 7:6 Tidskriftsartikel (refereegranskat)abstract Purpose: To show that adjustment of velocity encoding (VENC) for phase-contrast (PC) flow volume measurements is not necessary in modern MR scanners with effective background velocity offset corrections. Approach: The independence on VENC was demonstrated theoretically, but also experimentally on dedicated phantoms and on patients with chronic aortic regurgitation (n = 17) and one healthy volunteer. All PC measurements were performed using a modern MR scanner, where the pre-emphasis circuit but also a subsequent post-processing filter were used for effective correction of background velocity offset errors. Results: The VENC level strongly affected the velocity noise level in the PC images and, hence, the estimated peak flow velocity. However, neither the regurgitant blood flow volume nor the mean flow velocity displayed any clinically relevant dependency on the VENC level. Also, the background velocity offset was shown to be close to zero (
33.	Lagerstrand, Kerstin M, et al. (författare) Treatment decision in a 4-year-old-boy with left ventricular outpouching after advanced hemodynamical flow evaluation with 4Dflow CMR: A case report. 2022 Ingår i: Frontiers in pediatrics. - : Frontiers Media SA. - 2296-2360. ; 10 Tidskriftsartikel (refereegranskat)abstract Background: The present study presents a diagnostic course for the characterization of a congenital left ventricular outpouching (LVO) in a 4-year-old boy with severe neonatal heart failure, evaluating the added value of cardiac magnetic resonance (CMR) 4Dflow. Case presentation: A boy, born at full term, presented with heart failure immediately after birth. Echocardiography showed dilated left ventricle with poor function and LVO was initially interpreted as an aneurysm. No infection, inflammation, or other cause for heart failure was found. With intensive medical treatment, the heart function returned to normal, and eventually, all medication was terminated. At follow-up, surgical treatment of the LVO was discussed but after CMR 4Dflow, a thorough evaluation of the function of the left ventricle as well as the LVO was possible and the LVO was determined a double-chambered left ventricle with a good prognosis. Conclusions: The present case demonstrates the clinical usability of CMR 4Dflow for improved decision-making and risk assessment, revealing advanced hemodynamic flow patterns with no need for operation.
34.	Lagerstrand, Kerstin M, et al. (författare) Virtual magnetic resonance elastography has the feasibility to evaluate preoperative pituitary adenoma consistency. 2021 Ingår i: Pituitary. - : Springer Science and Business Media LLC. - 1573-7403 .- 1386-341X. ; 24, s. 530-541 Tidskriftsartikel (refereegranskat)abstract To evaluate the use of preoperative virtual Magnetic Resonance Elastography (vMRE) for patients undergoing transsphenoidal resection of pituitary adenomas (PA).Ten patients (60.2±19.6years; 8 males) were prospectively examined with the vMRE-method prior to transsphenoidal surgery. vMRE-images, reflecting tissue stiffness were reconstructed. From these images, histograms as well as the mean stiffness values over the tumor body were extracted. Finally, vMRE-data was compared with the PA consistency at surgery blinded to vMRE.In all patients, successful vMRE-examination was performed enabling evaluation of even small PAs. For tumors with homogenous tissue, the mean stiffness value increased with surgical consistency grading. For heterogenous tumors, however, the mean stiffness value did not consistently reflect the grading at surgery. On the other hand, the vMRE-images and histograms were found to be able to characterize the tumor heterogeneity and display focal regions of high stiffness that were found to affect the surgery outcome in these PAs. The vMRE-images and histograms showed great promise in characterizing the consistency at surgery for these PAs.Evaluation of PA consistency in preparation for surgery seems to be feasible using the vMRE-method. Our findings also address the need for high resolution diagnostic methods that can non-invasively display focal regions of increased stiffness, as such regions may increase the difficulty of transsphenoidal PA-resection.
35.	Nordanstig, Joakim, et al. (författare) A lower limb BOLD-MRI tissue perfusion protocol correlate to clinical disease stage, objective functional limitations, and health-related quality of life in patients with peripheral arterial occlusive disease 2022 Ingår i: Journal of Cardiovascular Medicine and Cardiology. - : Peertechz Publications Private Limited. - 2455-2976. ; 9:3, s. 028-029 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract While peripheral artery occlusive disease (PAOD) by large is a clinical diagnosis, further characterization of the ischemic state, procedural planning, and longitudinal follow-up after revascularisation are mainly based on imaging that delineates the arterial vasculature. Although several potential techniques have been suggested [1], there is still no clearly established imaging technique that directly quantifies the crucial PAOD pathophysiological process-tissue perfusion in the lower limb.
36.	Papalini, Evin, et al. (författare) Diagnosis of Acute Myocarditis Using Texture-Based Cardiac Magnetic Resonance, with CINE Imaging as a Novel Tissue Characterization Technique. 2022 Ingår i: Diagnostics (Basel, Switzerland). - : MDPI AG. - 2075-4418. ; 12:12 Tidskriftsartikel (refereegranskat)abstract Cardiac magnetic resonance (CMR) has emerged as a useful tool in the diagnostic work-up of patients with clinically suspected acute myocarditis (AM), yet the diagnosis remains challenging. The purpose of this proof-of-concept study was to evaluate if data-driven texture analysis has the feasibility to automatically distinguish between patients with and without CMR-verified AM using T2-weighted, late gadolinium enhancement, and CINE imaging. In particular, the present study investigated if functional CINE imaging could be used as a novel tissue characterization technique. Twenty patients with clinically suspected AM, separated into CMR-verified (n = 10) and non CMR-verified (n = 10) AM according to the Lake Louise criteria, were retrospectively included. Texture features were extracted from the images, compared on a group level, and correlated to the diagnostic outcome (CMR-verified versus non CMR-verified AM). Several features showed good to excellent reproducibility with very large differences between the groups, and moderate to strong correlation with the diagnostic outcome, suggesting that CMR texture analysis is a promising diagnostic tool for patients with clinically suspected AM. Furthermore, findings indicate that CINE imaging, which is currently used for the evaluation of cardiac function, might be a useful non-contrast-based technique for tissue characterization in patients with clinically suspected AM.
37.	Polte, Christian Lars, et al. (författare) Cardiovascular Magnetic Resonance in Myocarditis. 2022 Ingår i: Diagnostics (Basel, Switzerland). - : MDPI AG. - 2075-4418. ; 12:2 Tidskriftsartikel (refereegranskat)abstract Myocarditis is an inflammatory disease of the myocardium, and its diagnosis remains challenging owing to a varying clinical presentation and broad spectrum of underlying aetiologies. In clinical practice, cardiovascular magnetic resonance has become an invaluable non-invasive imaging tool in the evaluation of patients with clinically suspected myocarditis, mainly thanks to its unique multiparametric tissue characterization ability. Although considered as useful, the method also has its limitations. This review aims to provide an up-to-date overview of the strengths and weaknesses of cardiovascular magnetic resonance in the diagnostic work-up of patients with clinically suspected myocarditis in a broad clinical context.
38.	Polte, Christian Lars, et al. (författare) Somatostatin Receptor Positron Emission Tomography/Computed Tomography in Giant Cell Myocarditis: A Promising Approach to Molecular Myocardial Inflammation Imaging. 2022 Ingår i: Circulation. Cardiovascular imaging. - 1942-0080. ; 15:1 Tidskriftsartikel (refereegranskat)
39.	Rosenqvist, Louise, 1989, et al. (författare) Detailed MRI evaluation of the spine: a 2-year follow-up study of young individuals reporting different training doses 2023 Ingår i: European Spine Journal. - 0940-6719. ; 32, s. 4145-4152 Tidskriftsartikel (refereegranskat)abstract Objective To characterize the discs and vertebrae in detail over time in a group of adolescent individuals with varying training doses using magnetic resonance imaging (MRI).Method Thirty-five students were recruited from regular high schools (n=13) as well as schools with athlete competitive skiing programmes (n = 22). The thoraco-lumbar spine of all individuals was examined at baseline and at 2-year follow-up using the same 1.5T scanner and imaging protocol. The individuals were grouped based on their reported training dose: low-to-normal training dose (<= 5 h/week, n = 11, mean age 16.5 +/- 0.5 years) and high training dose (>5 h/week, n = 24, mean age 17.2 +/- 0.6 years.)Results At baseline, the signal intensity in the discs and vertebrae were significantly lower in individuals reporting high compared to low-to-normal training dose. The vertebral signal changed significantly over the 2-year period in both groups. However, only individuals reporting low-to-normal training dose displayed an overall disc signal change. Interestingly, the regional analysis displayed at baseline high annular signals in the more training-active individuals followed by a reduction over the two-year period.Conclusion This study suggests that disc degeneration is manifested earlier in individuals reporting a higher training dose. Over a 2-year period, however, the degeneration process did not accelerate further. Also, a significant difference in the vertebral signal, at baseline and follow-up as well as over time, could be seen between groups of individuals reporting high versus low-to-normal training dose.
40.	Sharma, Aseem, et al. (författare) Interpretation of Morphological Details of Nondegenerated Lumbar Intervertebral Discs on Magnetic Resonance Imaging: Insights From a Comparison Between Computed Tomography Discograms and Magnetic Resonance Imaging. 2022 Ingår i: Journal of computer assisted tomography. - 1532-3145. ; 46:3, s. 487-491 Tidskriftsartikel (refereegranskat)abstract To gain better insight into the magnetic resonance imaging (MRI) appearance of morphological intervertebral disc (IVD) details, such as annular and nucleus pulposus dimensions, by comparing contemporaneously obtained MRI and postdiscogram computed tomography (CT) scans of nondegenerated IVDs.Axial T2-weighted images and same-day postdiscography CTs, acquired after the MRI, of 26 normal-appearing lumbar IVDs (control IVDs at discography) were compared. The location and extent of central hyperintense zone on MRI and the extent of contrast distribution on CT relative to the IVD width (in anteroposterior [AP] and lateral planes) were assessed, with difference in measures between the modalities used to provide apparent inner annulus thickness and to estimate dimensions of also the outer annulus and location of nucleus pulposus.The mean (SD) extent of contrast distribution on CT discograms (53.1% [6.6%] and 58.1% [8.7%] of AP and lateral IVD width) was smaller than (P < 0.001 for both), and correlated weakly (r = 0.31 and 0.32 for AP and lateral planes) with corresponding measurements (58.4% [5.3%] and 65.7% [5.9%], respectively) for central hyperintense zone at MRI. The center of contrast opacification on CT discograms was located posterior to that of central T2 hyperintense zone on MRI in AP (P < 0.01), without any difference in lateral direction (P = 0.60).Normal-appearing lumbar IVDs are supported by outer annulus of larger relative thickness anteriorly, seen on both modalities. The shown discrepancy between the central T2 hyperintense zone and contrast distribution on CT discogram might reflect the inner annulus or structural changes within the borderzone nucleus and annulus. The exact nucleus size and inner annulus thickness could not be established due to a variable permeation of contrast across the central hyperintense zone on T2-weighted images.
41.	Simrén, Yvonne, 1966, et al. (författare) Diffusion tensor imaging based multiparametric characterization of renal lesions in infants with urinary tract infections: an explorative study 2021 Ingår i: Bmc Pediatrics. - : Springer Science and Business Media LLC. - 1471-2431. ; 21:1 Tidskriftsartikel (refereegranskat)abstract Background Conventional diffusion weighted imaging (DWI) is a promising non-invasive tool in the evaluation of infants with symptomatic urinary tract infections (UTI). The use of multiparametric diffusion tensor imaging (DTI) provides further information on renal pathology by reflecting renal microstructure. However, its potential to characterize and distinguish between renal lesions, such as acute pyelonephritic lesions, permanent renal damages or dysplastic changes has not been shown. This study aimed to evaluate the potential of multiparametric DTI for characterization of renal lesions with purpose to distinguish acute pyelonephritis from other renal lesions in young infants with their first UTI. Methods Nine kidneys in seven infants, age 1.0-5.6 months, with renal lesions i.e. uptake reductions, on acute scintigraphy performed after their first UTI, were included. The DTI examinations were performed during free breathing without sedation. The signal in the lesions and in normal renal tissue was measured in the following images: b0, b700, apparent diffusion coefficient (ADC), and fractional anisotropy (FA). In addition, DTI tractographies were produced for visibility. Results There was a difference between lesions and normal tissue in b700 signal (197 +/- 52 and 164 +/- 53, p = 0.011), ADC (1.22 +/- 0.11 and 1.45 +/- 0.15 mm(2)/s, p = 0.008), and FA (0.18 +/- 0.03 and 0.30 +/- 0.10, p = 0.008) for all nine kidneys. Six kidneys had focal lesions with increased b700 signal, decreased ADC and FA indicating acute inflammation. In three patients, the multiparametric characteristics of the lesions were diverging. Conclusion Multiparametric DTI has the potential to further characterize and distinguish acute pyelonephritis from other renal lesions in infants with symptomatic UTI.
42.	Simrén, Yvonne, 1966, et al. (författare) Diffusion weighted imaging is a promising method to detect acute pyelonephritis in non-sedated free breathing infants 2020 Ingår i: Journal of Pediatric Urology. - : Elsevier BV. - 1477-5131. ; 16, s. 320-325 Tidskriftsartikel (refereegranskat)abstract Introduction: Urinary tract infection (UTI) is a common disease in infants. The initial evaluation includes imaging to identify risk factors for permanent renal damage, such as malformation and renal parenchymal involvement of the infection i.e. pyelonephritis. 99mTc-Dimercaptosuccinic acid (DMSA) scintigraphy is a well-established method for detection of pyelonephritis and renal damage, but has limitations in availability, spatial resolution, and detection of congenital malformations. Diffusion weighted magnetic resonance imaging (DWI) has been shown to have a high sensitivity for detection of pyelonephritis in children without the use of invasive procedures, contrast agents or ionizing radiation. How this method performs in young infants during non-sedated free breathing remains, however, to be investigated. Objective: To prospectively assess the feasibility and performance of DWI for detection of pyelonephritis in non-sedated free breathing infants. Methods: 32 children <6 months of age with first-time symptomatic UTI were examined with DWI and DMSA scintigraphy. The DWI examination was performed using a free breathing protocol without the use of sedation. Pyelonephritic lesions were registered for both methods by independent observers. Agreement between DWI and DMSA was evaluated. Consensus diagnosis was determined and compared to the DWI findings. Results: The MRI and DMSA examinations were completed in 25 infants, with a median age of 1.7 (0.7–5.5) months. Focal uptake reductions were detected on the DMSA images in 12 (24%) of the 50 kidneys. The DWI method demonstrated a fair to good agreement with DMSA, k = 0.50 (p < 0.0001). The consensus diagnosis was pyelonephritis in eight (16%) of the 50 kidneys. DWI detected seven of the eight kidneys with pyelonephritis. No false positive findings were detected with DWI compared to consensus diagnosis. Discussion: This study has shown an agreement between DWI and DMSA scintigraphy in the detection of pyelonephritis. Further validation of the performance of DWI, using a consensus diagnosis as a reference, confirmed the potential of the method. This feasibility study included a limited number of patients and the results need to be confirmed in a prospective study of a larger cohort. Conclusion: Free breathing DWI is a promising method for detection of pyelonephritic lesions in non-sedated infants.[Formula presented] © 2020 Journal of Pediatric Urology Company
43.	Torén, Leif, et al. (författare) MRI During Spinal Loading Reveals Intervertebral Disc Behavior Corresponding to Discogram Findings of Annular Fissures and Pain Provocation. : Torén L, Lagerstrand K, Waldenberg C, Brisby H, Hebelka H. 2020 Ingår i: Spine. - 0362-2436 .- 1528-1159. ; 45:22 Tidskriftsartikel (refereegranskat)abstract Study design: Retrospective analysis of prospectively collected data. Objective: The aim of this study was to investigate whether spinal loading, depicted with magnetic resonance imaging (MRI), induces regional intervertebral disc (IVD) differences associated with presence and width of annular fissure and induced pain at discography. Summary of background data: Annular fissures play a role in low back pain (LBP) but cannot be accurately characterized with conventional MRI. Recently, annular fissures were suggested to influence different load-induced IVD behavior during MRI when comparing LBP-patients and controls. Thus, the loading effect could characterize behavior related to annular fissures noninvasively with MRI. Methods: Lumbar spines of 30 LBP-patients were investigated with MRI with and without loading, discography and CT. Five IVD regions were outlined on sagittal MRI images. Difference in normalized signal intensity (SI) with and without loading was calculated for each region. Eighty-three CT-discograms were graded regarding presence and width of fissures. Discograms were classified as pain-positive if a concordant pain response was obtained at a pressure <50 psi. Results: Comparing IVDs with outer fissures with IVDs without fissures, loading induced different behavior in the two ventral regions and in the posterior region. Higher SI increase in the central region was induced in IVDs with narrower fissures compared to IVDs with wider fissures. In the group of pain-negative discograms, a SI decrease was induced in the dorsal region whereas lack of such in the pain-positive group. Conclusion: The spinal loading-effect, depicted with MRI, reveals different regional behaviors between IVDs with outer fissures compared to those without, and between IVDs with narrow and broad fissures, as well as within posterior annulus between pain-positive and pain-negative discograms. Findings are of importance for future attempts to uncover phenotypes of painful IVDs.
44.	Truedsson, Frida, et al. (författare) Importance of complex blood flow in the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging. 2021 Ingår i: The international journal of cardiovascular imaging. - : Springer Science and Business Media LLC. - 1875-8312 .- 1569-5794 .- 1573-0743. ; 37, s. 3561-3572 Tidskriftsartikel (refereegranskat)abstract This study aimed to investigate if and how complex flow influences the assessment of aortic regurgitation (AR) using phase contrast MRI in patients with chronic AR. Patients with moderate (n=15) and severe (n=28) chronic AR were categorized into non-complex flow (NCF) or complex flow (CF) based on the presence of systolic backward flow volume. Phase contrast MRI was performed repeatedly at the level of the sinotubular junction (Ao1) and 1cm distal to the sinotubular junction (Ao2). All AR patients were assessed to have non-severe AR or severe AR (cut-off values: regurgitation volume (RVol)≥60ml and regurgitation fraction (RF)≥50%) in both measurement positions. The repeatability was significantly lower, i.e. variation was larger, for patients with CF than for NCF (≥12±12% versus≥6±4%, P≤0.03). For patients with CF, the repeatability was significantly lower at Ao2 compared to Ao1 (≥21±20% versus≥12±12%, P≤0.02), as well as the assessment of regurgitation (RVol: 42±34ml versus 54±42ml, P<0.001; RF: 30±18% versus 34±16%, P=0.01). This was not the case for patients with NCF. The frequency of patients that changed in AR grade from severe to non-severe when the position of the measurement changed from Ao1 to Ao2 was higher for patients with CF compared to NCF (RVol: 5/26 (19%) versus 1/17 (6%), P=0.2; RF: 4/26 (15%) versus 0/17 (0%), P=0.09). Our study shows that complex flow influences the quantification of chronic AR, which can lead to underestimation of AR severity when using PC-MRI.
45.	Törngren, Kristina, et al. (författare) A Reperfusion BOLD-MRI Tissue Perfusion Protocol Reliably Differentiate Patients with Peripheral Arterial Occlusive Disease from Healthy Controls 2021 Ingår i: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 10:16 Tidskriftsartikel (refereegranskat)abstract There is no established technique that directly quantifies lower limb tissue perfusion. Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) is an MRI technique that can determine skeletal muscle perfusion. BOLD-MRI relies on magnetic differences of oxygenated and deoxygenated hemoglobin, and regional changes in oxy/deoxyhemoglobin ratio can be recorded by T2* weighted MRI sequences. We aimed to test whether BOLD-MRI can differentiate lower limb tissue perfusion in peripheral arterial occlusive disease (PAOD) patients and healthy controls. Twenty-two PAOD patients and ten healthy elderly volunteers underwent lower limb BOLD-MRI. Reactive hyperemia was provoked by transient cuff compression and images of the gastrocnemius and soleus muscles were continuously acquired at rest, during ischemia and reperfusion. Key BOLD parameters were baseline T2* absolute value and time to T2* peak value after cuff deflation (TTP). Correlations between imaging parameters and ankle-brachial index (ABI) was investigated. The mean TTP was considerably prolonged in PAOD patients compared to healthy controls (m. gastrocnemius: 111 +/- 46 versus 48 +/- 22 s, p = 0.000253; m. soleus: 100 +/- 42 versus 41 +/- 30 s, p = 0.000216). Both gastrocnemius and soleus TTP values correlated strongly with ABI (-0.82 and -0.78, p < 0.01). BOLD-MRI during reactive hyperemia differentiated most PAOD patients from healthy controls. TTP was the most decisive parameter and strongly correlated with the ABI.
46.	Waldenberg, Christian, 1987, et al. (författare) Associations between Vertebral Localized Contrast Changes and Adjacent Annular Fissures in Patients with Low Back Pain: A Radiomics Approach 2023 Ingår i: Journal of Clinical Medicine. - 2077-0383. ; 12:15 Tidskriftsartikel (refereegranskat)abstract Low back pain (LBP) is multifactorial and associated with various spinal tissue changes, including intervertebral disc fissures, vertebral pathology, and damaged endplates. However, current radiological markers lack specificity and individualized diagnostic capability, and the interactions between the various markers are not fully clear. Radiomics, a data-driven analysis of radiological images, offers a promising approach to improve evaluation and deepen the understanding of spinal changes related to LBP. This study investigated possible associations between vertebral changes and annular fissures using radiomics. A dataset of 61 LBP patients who underwent conventional magnetic resonance imaging followed by discography was analyzed. Radiomics features were extracted from segmented vertebrae and carefully reduced to identify the most relevant features associated with annular fissures. The results revealed three important texture features that display concentrated high-intensity gray levels, extensive regions with elevated gray levels, and localized areas with reduced gray levels within the vertebrae. These features highlight patterns within vertebrae that conventional classification systems cannot reflect on distinguishing between vertebrae adjacent to an intervertebral disc with or without an annular fissure. As such, the present study reveals associations that contribute to the understanding of pathophysiology and may provide improved diagnostics of LBP.
47.	Waldenberg, Christian, 1987, et al. (författare) Detection of Imperceptible Intervertebral Disc Fissures in Conventional MRI-An AI Strategy for Improved Diagnostics. 2022 Ingår i: Journal of clinical medicine. - : MDPI AG. - 2077-0383. ; 12:1 Tidskriftsartikel (refereegranskat)abstract Annular fissures in the intervertebral discs are believed to be closely related to back pain. However, no sensitive non-invasive method exists to detect annular fissures. This study aimed to propose and test a method capable of detecting the presence and position of annular fissures in conventional magnetic resonance (MR) images non-invasively. The method utilizes textural features calculated from conventional MR images combined with attention mapping and artificial intelligence (AI)-based classification models. As ground truth, reference standard computed tomography (CT) discography was used. One hundred twenty-three intervertebral discs in 43 patients were examined with MR imaging followed by discography and CT. The fissure classification model determined the presence of fissures with 100% sensitivity and 97% specificity. Moreover, the true position of the fissures was correctly determined in 90 (87%) of the analyzed discs. Additionally, the proposed method was significantly more accurate at identifying fissures than the conventional radiological high-intensity zone marker. In conclusion, the findings suggest that the proposed method is a promising diagnostic tool to detect annular fissures of importance for back pain and might aid in clinical practice and allow for new non-invasive research related to the presence and position of individual fissures.

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