| 1. |
- Sigurdsson, Ulf, et al.
(author)
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Delayed gadolinium-enhanced MRI of meniscus (dGEMRIM) and cartilage (dGEMRIC) in healthy knees and in knees with different stages of meniscus pathology
- 2016
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In: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 17:1
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Journal article (peer-reviewed)abstract
- Background: Lesions in the meniscus are risk factors for developing knee osteoarthritis (OA), not least because of the role of the meniscus in the pathological progression of OA. Delayed gadolinium enhanced MRI of cartilage (dGEMRIC) has extensively been used to identify pre-radiographic cartilage changes in OA. In contrast, its counterpart with regard to examination of the meniscus, gadolinium enhanced MRI of meniscus (dGEMRIM), has been less utilized. In this study we use 3D dGEMRIM in patients with meniscus lesions and compare them with previous results of healthy individuals. Methods: Eighteen subjects with MRI-verified posteromedial meniscus lesions and 12 healthy subjects with non-injured and non-symptomatic knee joints, together 30 volunteers, were examined using 3D Look-Locker sequence after intravenous injection of Gd-DTPA2- (0.2 mmol/kg body weight). Relaxation time (T1) was measured in the posterior meniscus and femoral cartilage before and 60, 90, 120 and 180 min after injection. Relaxation rate (R1 = 1/T1) and change in relaxation rate (ΔR1) were calculated. For statistical analyses, Student's t-test and Analysis of Variance (ANOVA) were used. Results: The pre-contrast diagnostic MRI identified two sub-cohorts in the 18 patients with regard to meniscus injury: 1) 11 subjects with MRI verified pathological intrameniscal changes (grade 2) in the posteromedial meniscus only and no obvious cartilage changes. The lateral meniscus showed no pathology. 2) 7 subjects with MRI verified pathological rupture (grade 3) of the posteromedial meniscus and pathological changes in the lateral meniscus and/or medial and lateral joint cartilage. Comparisons of pathological and healthy posteromedial meniscus revealed opposite patterns in both T1Gd and ΔR1 values between pathological meniscus grade 2 and grade 3. The concentration of the contrast agent was lower than in healthy meniscus in grade 2 lesions (p = 0.046) but tended to increase in grade 3 lesions (p = 0.110). Maximum concentration of contrast agent was reached after 180 min in both cartilage and menisci (except for grade 3 menisci where the maximum concentration was reached after 90 min). Conclusion: dGEMRIM and dGEMRIC may be feasible to combine in vivo, preferably with one examination before and one 2 h after contrast injection. Possible different dGEMRIM patterns at different stages of meniscus lesions must be taken into account when evaluating meniscus pathology.
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| 2. |
- Sigurdsson, Ulf, et al.
(author)
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In vivo transport of Gd-DTPA(2-) into human meniscus and cartilage assessed with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC)
- 2014
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In: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 15
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Journal article (peer-reviewed)abstract
- Background: Impaired stability is a risk factor in knee osteoarthritis (OA), where the whole joint and not only the joint cartilage is affected. The meniscus provides joint stability and is involved in the early pathological progress of OA. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) has been used to identify pre-radiographic changes in the cartilage in OA, but has been used less commonly to examine the meniscus, and then using only a double dose of the contrast agent. The purpose of this study was to enable improved early OA diagnosis by investigate the temporal contrast agent distribution in the meniscus and femoral cartilage simultaneously, in healthy volunteers, using 3D dGEMRIC at two different doses of the contrast agent Gd-DTPA(2-). Methods: The right knee in 12 asymptomatic volunteers was examined using a 3D Look-Locker sequence on two occasions after an intravenous injection of a double or triple dose of Gd-DTPA(2-) (0.2 or 0.3 mmol/kg body weight). The relaxation time (T-1) and relaxation rate (R-1 = 1/T-1) were measured in the meniscus and femoral cartilage before, and 60, 90, 120 and 180 minutes after injection, and the change in relaxation rate (Delta R-1) was calculated. Paired t-test and Analysis of Variance (ANOVA) were used for statistical evaluation. Results: The triple dose yielded higher concentrations of Gd-DTPA(2-) in the meniscus and cartilage than the double dose, but provided no additional information. The observed patterns of Delta R-1 were similar for double and triple doses of the contrast agent. Delta R-1 was higher in the meniscus than in femoral cartilage in the corresponding compartments at all time points after injection. Delta R-1 increased until 90-180 minutes in both the cartilage and the meniscus (p < 0.05), and was lower in the medial than in the lateral meniscus at all time points (p < 0.05). A faster increase in Delta R-1 was observed in the vascularized peripheral region of the posterior medial meniscus, than in the avascular central part of the posterior medial meniscus during the first 60 minutes (p < 0.05). Conclusion: It is feasible to examine undamaged meniscus and cartilage simultaneously using dGEMRIC, preferably 90 minutes after the injection of a double dose of Gd-DTPA(2-) (0.2 mmol/kg body weight).
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| 3. |
- Siversson, Carl, et al.
(author)
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Effects of B(1) inhomogeneity correction for three-dimensional variable flip angle T(1) measurements in hip dGEMRIC at 3 T and 1.5 T.
- 2012
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In: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 67:6, s. 1776-1781
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Journal article (peer-reviewed)abstract
- Delayed gadolinium-enhanced MRI of cartilage is a technique for studying the development of osteoarthritis using quantitative T(1) measurements. Three-dimensional variable flip angle is a promising method for performing such measurements rapidly, by using two successive spoiled gradient echo sequences with different excitation pulse flip angles. However, the three-dimensional variable flip angle method is very sensitive to inhomogeneities in the transmitted B(1) field in vivo. In this study, a method for correcting for such inhomogeneities, using an additional B(1) mapping spin-echo sequence, was evaluated. Phantom studies concluded that three-dimensional variable flip angle with B(1) correction calculates accurate T(1) values also in areas with high B(1) deviation. Retrospective analysis of in vivo hip delayed gadolinium-enhanced MRI of cartilage data from 40 subjects showed the difference between three-dimensional variable flip angle with and without B(1) correction to be generally two to three times higher at 3 T than at 1.5 T. In conclusion, the B(1) variations should always be taken into account, both at 1.5 T and at 3 T. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.
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| 4. |
- Siversson, Carl, et al.
(author)
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Local Flip Angle Correction for Improved Volume T1-Quantification in Three-Dimensional dGEMRIC Using the Look-Locker Technique
- 2009
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 30:4, s. 834-841
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Journal article (peer-reviewed)abstract
- Purpose: To present an evaluation method for three-dimensional Look-Locker (3D-LL) based T1 quantification, calculating correct T1 values independent of local flip angle (FA) variations. The method was evaluated both in phantoms and in vivo in a delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) study with 33 subjects. Materials and Methods: T1 was measured with 3D-LL, using both local FA correction and a precalculated FA slice profile. and compared with standard constant FA correction, for all slices in phantoms and in both femur condyles in vivo. T1 measured using two-dimensional Inversion Recovery (2D-IR) was used as gold standard. Results: Due to the FA being slice dependent, the standard constant FA correction results in erroneous T1 (systematic error = 109.1 ms in vivo), especially in the outer slices. With local FA correction. the calculated T1 is excellent for all slices in phantoms (<5% deviation from 2D-IR). In vivo the performance is lower (systematic error = -57.5ms), probably due to imperfect inversion. With precalculated FA correction the performance is very good also in vivo (systematic error = 13.3 ms). Conclusion: With the precalculated FA correction method, the 3D-LL sequence is robust enough for in vivo dGEMRIC, even outside the centermost slices.
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| 5. |
- Siversson, Carl, et al.
(author)
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Repeatability of T1-quantification in dGEMRIC for three different acquisition techniques: two-dimensional inversion recovery, three-dimensional look locker, and three-dimensional variable flip angle.
- 2010
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 31:5, s. 1203-1209
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate the repeatability of the dGEMRIC (delayed gadolinium enhanced MRI of cartilage) method in osteoarthritis-prone knee joints for three different T1 quantification techniques: two-dimensional inversion recovery (2D-IR), three-dimensional Look-Locker (3D-LL), and three-dimensional variable flip angle (3D-VFA). MATERIALS AND METHODS: Nine subjects were examined twice, with a 2-week interval, using all three measurement techniques. Four regions of interest were defined in the central medial and lateral femoral cartilage. The repeatability was evaluated for each measurement technique. For the 3D techniques, the variation between different slices was also evaluated. RESULTS: Repeatability expressed by root-mean-square coefficient of variation (CV(RMS)) showed similar results for 2D-IR and 3D-LL (5.4-8.4%). For 3D-VFA CV(RMS) was higher (9.3-15.2%). Intraclass correlation coefficient showed both 2D-IR and 3D-LL reliability to be moderate, while 3D-VFA reliability was low. Inter-slice CV(RMS) and ICC was of the same magnitude as the repeatability. No clear differences could be interpreted between the condyles. CONCLUSION: Both 2D-IR and 3D-LL perform well in generating repeatable dGEMRIC results, while 3D-VFA results are somewhat inferior. Furthermore, repeatability results in this study are similar to previously published results for healthy subjects. Finally, the positioning of the analyzed images is crucial to generate reliable repeatability results.
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| 6. |
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| 7. |
- Örtegren, Jakob, et al.
(author)
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Unthreaded Fixation of Slipped Capital Femoral Epiphysis Leads to Continued Growth of the Femoral Neck.
- 2015
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In: Journal of Pediatric Orthopaedics. - 0271-6798.
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Journal article (peer-reviewed)abstract
- The optimal treatment for slipped capital femoral epiphysis (SCFE) remains controversial. In Sweden, the standard treatment is unthreaded fixation over the physis, with the purpose to permit continued growth of the femoral neck. The aim of the present study was to verify and quantify longitudinal growth of the femoral neck after in situ pinning with the Hansson hook-pin.
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| 8. |
- Bulat, Evgeny, et al.
(author)
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Planar dGEMRIC Maps May Aid Imaging Assessment of Cartilage Damage in Femoroacetabular Impingement
- 2016
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In: Clinical Orthopaedics and Related Research. - : Ovid Technologies (Wolters Kluwer Health). - 0009-921X. ; 474:2, s. 467-478
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Journal article (peer-reviewed)abstract
- Three-dimensional (3-D) delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) helps quantify biochemical changes in articular cartilage that correlate with early-stage osteoarthritis. However, dGEMRIC analysis is performed slice by slice, limiting the potential of 3-D data to give an overall impression of cartilage biochemistry. We previously developed a computational algorithm to produce unfolded, or "planar," dGEMRIC maps of acetabular cartilage, but have neither assessed their application nor determined whether MRI-based grading of cartilage damage or dGEMRIC measurements predict intraoperative findings in hips with symptomatic femoroacetabular impingement (FAI). (1) Does imaging-based assessment of acetabular cartilage damage correlate with intraoperative findings in hips with symptomatic FAI? (2) Does the planar dGEMRIC map improve this correlation? (3) Does the planar map improve the correlation between the dGEMRIC index and MRI-based grading of cartilage damage in hips with symptomatic FAI? (4) Does the planar map improve imaging-based evaluation time for hips with symptomatic FAI? We retrospectively studied 47 hips of 45 patients with symptomatic FAI who underwent hip surgery between 2009 and 2013 and had a 1.5-T 3-D dGEMRIC scan within 6 months preoperatively. Our cohort included 25 males and 20 females with a mean +/- SD age at surgery of 29 +/- 11 years. Planar dGEMRIC maps were generated from isotropic, sagittal oblique TrueFISP and T1 sequences. A pediatric musculoskeletal radiologist with experience in hip MRI evaluated studies using radially reformatted sequences. For six acetabular subregions (anterior-peripheral [AP]; anterior-central [AC]; superior-peripheral [SP]; superior-central [SC]; posterior-peripheral [PP]; posterior-central [PC]), modified Outerbridge cartilage damage grades were recorded and region-of-interest T1 averages (the dGEMRIC index) were measured. Beck's intraoperative cartilage damage grades were compared with the Outerbridge grades and dGEMRIC indices. For a subset of 26 hips, 13 were reevaluated with the map and 13 without the map, and total evaluation times were recorded. There were no meaningful differences in the correlations obtained with versus without referencing the planar maps. Planar map-independent Outerbridge grades had a notable (p < 0.05) Spearman's rank correlation (rho) with Beck's grades that was moderate in AP, SC, and PC (0.3 < rho < 0.5) and strong in SP (rho > 0.5). For map-dependent Outerbridge grades, rho was moderate in AP, AC, and SC and strong in SP. Map-independent dGEMRIC indices had a rho with Beck's grades that was moderate in AP and SC (-0.3 > rho > -0.5) and strong in SP (rho < -0.5). For map-dependent dGEMRIC indices, rho was moderate in SC and strong in SP. Similarly, there were no meaningful, map-dependent differences in the correlations. When comparing Outerbridge grades and dGEMRIC indices, there were notable correlations across all subregions. Without the planar map, rho was moderate in AC and PC and strong in AP, SP, SC, and PP. With the map, rho was strong in all six subregions. In AC, there was a notable map-dependent improvement in this correlation (p < 0.001). Finally, referencing the planar dGEMRIC map during evaluation was associated with a decrease in mean evaluation time, from 207 +/- 32 seconds to 152 +/- 33 seconds (p = 0.001). Our work challenges the weak correlation between dGEMRIC and intraoperative findings of cartilage damage that was previously reported in hips with symptomatic FAI, suggesting that dGEMRIC has potential diagnostic use for this patient population. The planar dGEMRIC maps did not meaningfully alter the correlation of imaging-based evaluation of cartilage damage with intraoperative findings; however, they notably improved the correlation of dGEMRIC and MRI-based grading in AC, and their use incurred no additional time cost to imaging-based evaluation. Therefore, the planar maps may improve dGEMRIC's use as a continuous proxy for an otherwise discrete and simplified MRI-based grade of cartilage damage in hips with symptomatic FAI. Level III, diagnostic study.
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| 9. |
- Holmer, Helene, et al.
(author)
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Hypothalamic involvement predicts cardiovascular risk in adults with childhood onset craniopharyngioma on long-term GH therapy.
- 2009
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In: European Journal of Endocrinology. - 0804-4643 .- 1479-683X. ; 16, s. 671-679
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Journal article (peer-reviewed)abstract
- Context: Craniopharyngioma patients without GH therapy are at an increased cardiovascular disease (CVD) risk and particularly concerning women. No previous study on long-term GH therapy in adults with childhood onset (CO) craniopharyngioma was identified. Objective: To investigate CVD risk in adults with CO craniopharyngioma on complete hormone replacement, including long-term GH therapy, and to investigate the impact of disease-related factors on CVD risk. Design and participants: In a cross-sectional study of operated CO craniopharyngiomas (1958–2000) from a defined area of Sweden (2.5 million), we enrolled 42 patients (20 women) with a median age of 28 years (range 17–57) and assessed CVD risk of 20 (4–40) years after first operation. Comparisons were made with matched controls and between patients with tumor growth into the third ventricle (TGTV) versus non-TGTV. GH therapy was 10–12 years in women and men. Results: In comparison with controls, both male and female patients had increased body mass index, fat mass, insulin, and leptin levels. Overall, while not significantly increased in male patients, 55–60% of female patients had a medium–high CVD risk, compared with 10–20% in controls. An increased CVD risk (all P<0.05) and higher levels of fat mass and insulin were recorded in the TGTV group versus the non-TGTV group. Late puberty induction and lack of androgens were shown in female patients. Conclusions: Adult patients with CO craniopharyngioma, especially those with TGTV, have persistently increased CVD risk. Conventional hormone substitution, including GH, is insufficient to normalize CVD risk, suggesting an important role for irreversible hypothalamic dysfunction.
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| 10. |
- Lerner, Minna, et al.
(author)
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Clinical validation of a commercially available deep learning software for synthetic CT generation for brain
- 2021
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In: Radiation Oncology. - : Springer Science and Business Media LLC. - 1748-717X. ; 16:1
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Journal article (peer-reviewed)abstract
- Background: Most studies on synthetic computed tomography (sCT) generation for brain rely on in-house developed methods. They often focus on performance rather than clinical feasibility. Therefore, the aim of this work was to validate sCT images generated using a commercially available software, based on a convolutional neural network (CNN) algorithm, to enable MRI-only treatment planning for the brain in a clinical setting. Methods: This prospective study included 20 patients with brain malignancies of which 14 had areas of resected skull bone due to surgery. A Dixon magnetic resonance (MR) acquisition sequence for sCT generation was added to the clinical brain MR-protocol. The corresponding sCT images were provided by the software MRI Planner (Spectronic Medical AB, Sweden). sCT images were rigidly registered and resampled to CT for each patient. Treatment plans were optimized on CT and recalculated on sCT images for evaluation of dosimetric and geometric endpoints. Further analysis was also performed for the post-surgical cases. Clinical robustness in patient setup verification was assessed by rigidly registering cone beam CT (CBCT) to sCT and CT images, respectively. Results: All sCT images were successfully generated. Areas of bone resection due to surgery were accurately depicted. Mean absolute error of the sCT images within the body contour for all patients was 62.2 ± 4.1 HU. Average absorbed dose differences were below 0.2% for parameters evaluated for both targets and organs at risk. Mean pass rate of global gamma (1%/1 mm) for all patients was 100.0 ± 0.0% within PTV and 99.1 ± 0.6% for the full dose distribution. No clinically relevant deviations were found in the CBCT-sCT vs CBCT-CT image registrations. In addition, mean values of voxel-wise patient specific geometric distortion in the Dixon images for sCT generation were below 0.1 mm for soft tissue, and below 0.2 mm for air and bone. Conclusions: This work successfully validated a commercially available CNN-based software for sCT generation. Results were comparable for sCT and CT images in both dosimetric and geometric evaluation, for both patients with and without anatomical anomalies. Thus, MRI Planner is feasible to use for radiotherapy treatment planning of brain tumours.
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