| 1. |
- Hörberg, Lisa, et al.
(författare)
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Reproducibility of measurements with a semi-automatic software package for the evaluation of rectal cancer
- 2020
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 61:5, s. 586-594
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Tidskriftsartikel (refereegranskat)abstract
- Background: Staging of rectal cancer with MRI has major impact on treatment choice and may be of importance in new cancer management strategies such as “wait-and-see” policy. Purpose: To assess the reproducibility of a software package recently developed at our department to measure volumes, apparent diffusion coefficient, and the skewness of apparent diffusion coefficient in lymph nodes and tumors in rectal cancer patients before and after chemoradiation treatment. Material and Methods: This study included 20 consecutive patients with biopsy-verified rectal cancer, in whom MRI staging had been performed both before and after chemoradiation treatment. The diffusion-weighted images were transferred to the software. The volume, apparent diffusion coefficient, and skewness were determined for 93 lymph nodes and 40 tumors. The volumes were compared with manual measurements of the volume of the same lymph nodes and tumors. Results: The agreement in semi-automatic measurements of lymph nodes was very good (ICC = 0.99), and in tumors good (ICC = 0.88). The agreement in manual measurements of lymph nodes was very good (ICC = 0.95) when all lymph nodes were included, but low (ICC = 0.52) if three outliers were excluded. Bland–Altman plots showed clear agreement between manual and semi-automatic measurements in the lymph nodes, but not in measurements of tumors. The values of apparent diffusion coefficient and skewness in tumors differed before and after treatment but did not differ in lymph nodes as a group. Conclusion: The software package showed a high degree of reproducibility in measurements on lymph nodes but requires further development to improve the reproducibility of tumor measurements.
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| 2. |
- Nyman, Ulf, et al.
(författare)
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Preventing contrast medium-induced acute kidney injury: Side-by-side comparison of Swedish-ESUR guidelines
- 2018
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 28:12, s. 5384-5395
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Tidskriftsartikel (refereegranskat)abstract
- A side-by-side comparison of updated guidelines regarding contrast medium-induced acute kidney injury (CI-AKI) from the Swedish Society of Uroradiology (SSUR) and the European Society of Urogenital Radiology (ESUR) is presented. The major discrepancies include a higher glomerular filtration rate (GFR) threshold as a risk factor for CI-AKI and for discontinuation of metformin by SSUR, i.e., < 45 ml/min versus < 30 ml/min/1.73 m(2) by ESUR, when intravenous or intra-arterial contrast media (CM) with second-pass renal exposure is administered. SSUR also continues to recommend consideration of traditional non-renal risk factors such as diabetes and congestive heart failure, while ESUR considers these factors as non-specific for CI-AKI and does not recommend anyconsideration. Contrary to ESUR, SSUR also recommends discontinuation of NSAID and nephrotoxic medication if possible. Insufficient evidence at the present time motivates the more cautionary attitude taken by SSUR. Furthermore, SSUR expresses GFR thresholds in absolute values in ml/min as recommended by the National Kidney Foundation for drugs excreted by glomerular filtration, while ESUR uses the relative GFR normalised to body surface area in ml/min/1.73 m(2). CM dose/GFR ratio thresholds established for coronary angiography/interventions are also applied as recommendations for CM-enhanced CT by SSUR, since SSUR regards coronary procedures as a second-pass renal exposure of CM with no obvious difference in the incidence of AKI compared withIV CM administration. Finally, SSUR recommends reducing the gram-iodine dose/GFR ratio from < 1.0 in patients not at risk to < 0.5 in patients at risk of CI-AKI, while ESUR has no such recommendation.Key Points center dot The more cautionary attitude taken by SSUR compared with that of ESUR is motivated by insufficient evidence regarding risk for contrast medium-induced acute kidney injuries (CI-AKI).center dot SSUR recommends that absolute and not relative GFR should be used when dosing drugs eliminated by the kidneys such as contrast media.center dot According to SSUR the gram-iodine dose/GFR ratio should be < 0.5 in patients at risk of CI-AKI, while ESUR has no such recommendation.
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| 3. |
- Nyman, Ulf, et al.
(författare)
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Revised Swedish guidelines on intravenous iodine contrast medium-induced acute kidney injury 2022: A summary
- 2023
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 64:5
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Forskningsöversikt (refereegranskat)abstract
- The Swedish Society of Uroradiology has revised their computed tomography (CT) guidelines regarding iodine contrast media-induced acute kidney injury (CI-AKI). They are more cautious compared to the European Society of Urogenital Radiology and the American College of Radiology since the actual risk of CI-AKI remains uncertain in patients with moderate to severe kidney damage due to a lack of prospective controlled studies and mainly based on retrospective propensity score-matched studies with low-grade evidence. Another source of uncertainty is the imprecision of glomerular filtration rate (GFR) estimating equations. However, randomized hydration studies indictae an upper limit risk of CI-AKI of about 5% for outpatients with a GFR in the range of 30-44 or 45-59 mL/min/1.73m(2) combined with multiple risk factors. Apart from GFR limits, the guideline also includes limits for systemic contrast medium exposure expressed in gram-iodine/GFR ratio.
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| 4. |
- Trinh, Lena, et al.
(författare)
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In vivo comparison of MRI-based and MRS-based quantification of adipose tissue fatty acid composition against gas chromatography
- 2020
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 0740-3194 .- 1522-2594. ; 84:5, s. 2484-2494
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To compare MR-based fatty acid composition (FAC) quantification methods against the gold standard technique, gas chromatography (GC), with comparison of a free and a constrained signal model. The FAC was measured in the healthy and edematous legs of lymphedema patients. Methods: In vivo MRS and MRI data were acquired from 19 patients at 3 T. Biopsies were collected from subcutaneous adipose tissue of both thighs during liposuction. The saturated, monounsaturated, and polyunsaturated fatty acid fractions (fSFA, fMUFA and fPUFA, respectively) were estimated with the MR-based methods using two signal models: free and constrained (number of methylene-interrupted double bonds expressed in number of double bonds, based on GC data). Linear regression, Bland–Altman plots, and correlation coefficients were used to evaluate the MR methods against the GC of the biopsies. Paired t-test was used to compare the FAC difference between edematous and healthy legs. Results: The estimated parameters correlated well with the GC data (rSFA, rMUFA, and rPUFA = 0.82, 0.81 and 0.89, respectively) using the free model MRI-based approach. In comparison, the MRS-based method resulted in weaker correlations and larger biases compared with MRI. In both cases, correct estimation of fMUFA and fPUFA fractions were not possible using the constrained model. The difference in FAC of healthy and edematous legs were estimated to 0.008 (P =.01), −0.009 (P =.005), and 0.002 (P =.03) for fSFA, fMUFA, and fPUFA. Conclusion: In this study, MRI-based FAC quantification was highly correlated, although slightly biased, compared with GC, whereas the MRS-based approach resulted in weaker correlations. Small but significant differences could be found between the healthy and edematous legs of lymphedema patients using GC analysis.
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| 5. |
- Tufvesson, Hanna, et al.
(författare)
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Quantified small bowel motility in patients with ulcerative colitis and gastrointestinal symptoms : a pilot study
- 2021
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 62:7, s. 858-866
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Tidskriftsartikel (refereegranskat)abstract
- Background: Gastrointestinal (GI) symptoms are common in patients with ulcerative colitis (UC), even when the disease is in remission, possibly due to abnormalities in GI motility. Small bowel motility can be assessed globally and in specific intestinal regions during magnetic resonance enterography (MRE) using a displacement mapping technique. Purpose: To investigate whether small bowel motility in MRE differs between patients with UC and controls, and if altered motility correlates with GI symptoms. Material and Methods: In 2016–2018, patients who were admitted for MRE, regardless of clinical indication, were consecutively invited to the study. Healthy volunteers were recruited. The participants completed a questionnaire regarding GI symptoms and relevant clinical data were reviewed in the medical records. The dynamic imaging series obtained during MRE were sent for motility mapping and a motility index (MI) was calculated in jejunum, ileum and terminal ileum in all participants. Results: In total, 224 patients and healthy volunteers were enrolled in the study. Fifteen were diagnosed with UC and 22 were considered healthy controls. In UC, the prevalence of GI symptoms was higher than in controls (P < 0.001), both in remission and in active disease. There was no correlation between GI symptoms and small bowel motility in UC. Jejunal motility was lower in UC than in controls (P = 0.049). Conclusion: Jejunal motility is decreased in UC compared with healthy controls, but there is no relationship between small bowel motility and GI symptoms in UC.
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| 6. |
- Elmståhl, Barbara, et al.
(författare)
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Iodixanol 320 results in better renal tolerance and radiodensity than do gadolinium-based contrast media: Arteriography in ischemic porcine kidneys
- 2008
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 1527-1315 .- 0033-8419. ; 247:1, s. 88-97
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To prospectively compare nephrotoxicity and radiodensity of plasma hyperosmotic gadolinium chelates (attenuation-osmotic ratio of 1: 1) with those of plasma iso-osmotic iodine-based contrast media (attenuation-osmotic ratio of 3: 1 or 6: 1) after renal arteriography in ischemic porcine kidneys. Materials and Methods: The local animal care committee approved this study. The following contrast media were used: (a) iodixanol (150 mg of iodine per milliliter and 320 mg I/mL, 0.29 osm/kg H2O), (b) iopromide (150 mg I/mL, 0.34 osm/kg), (c) 0.5 mol/L gadodiamide (0.78 osm/kg), and (d) 1.0 mol/L gadobutrol (1.6 osm/kg). After left-sided nephrectomy, contrast media (3 mL per kilogram of body weight) were injected (20 mL/min) in a noncrossover design into the right renal artery of pigs during a 10-minute ischemic period. There were eight pigs in each group and one group for each contrast medium. We compared histomorphology, radiographic contrast medium excretion, subjective radiodensity of nephrograms (70 kVp) at the end of injection, and contrast medium plasma half-life elimination times 1-3 hours after injection. Longer elimination times resulted in lower glomerular filtration rates. Results: Gadobutrol caused extensive tubular necrosis and moderate glomerular necrosis; gadodiamide and iopromide, minimal to mild tubular necrosis; and iodixanol, no necrosis. Gadobutrol was the only contrast medium to show no sign of excretion, and its plasma half-life elimination time (median, 1103 minutes; P = .001) was significantly longer than that of other contrast agents. Gadodiamide had a significantly longer plasma half-life elimination time (median, 209 minutes; P = .01) than did iodine-based contrast media (median, 136-142 minutes). The 320 mg I/mL dose of iodixanol had the highest radiodensity, whereas gadodiamide had the lowest radiodensity. The radiodensity of the 320 mg I/mL dose of iodixanol was greater than that of the 150 mg I/mL dose of iodixanol, which was equal to the radiodensities of the 150 mg I/mL dose of iopromide and 1.0 mol/L gadobutrol, which in turn were greater than that of 0.5 mol/L gadodiamide. Conclusion: Plasma iso-osmotic iodine-based contrast media used at commercially available concentrations have superior attenuation and nephrotoxic profiles compared with equal volumes of hyperosmotic nonionic 0.5-1.0 mol/L gadolinium-based contrast media when performing renal arteriographic procedures. (c) RSNA, 2008.
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| 7. |
- Aho Fält, Tobias, et al.
(författare)
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Simulated Dose Reduction for Abdominal CT With Filtered Back Projection Technique: Effect on Liver Lesion Detection and Characterization
- 2019
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Ingår i: American Journal of Roentgenology: diagnostic imaging and related sciences. - 0361-803X. ; 212:1, s. 84-93
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE. Previous studies have shown the possibility to reduce radiation dose in abdominal CT by 25–50% without negatively affecting detection of liver lesions. How radiation dose reduction affects characterization of liver metastases is not as well known. The objective of this study was to investigate how different levels of simulated dose reduction affect the detection and characterization of liver lesions, primarily hypovascular metastases. A secondary objective was to analyze the relationship between the lesion size and contrast-to-noise ratio (CNR) and the detection rate.MATERIALS AND METHODS. Thirty-nine patients (19 with metastases and 20 without) were retrospectively selected. The following radiation dose levels (DLs) were simulated: 100% (reference level), 75%, 50%, and 25%. Five readers were asked to mark liver lesions and rate the probability of malignancy on a 5-grade Likert scale. Noninferiority analysis using the jackknife free-response ROC (JAFROC) method was performed as well as direct comparison of detection rates and grades.RESULTS. JAFROC analysis showed noninferior detection and characterization of metastases at DL75 as compared with DL100. However, the number of benign lesions and false-positive localizations rated as “suspected malignancy” was significantly higher at DL75.CONCLUSION. Radiation dose can be reduced by 25% without negatively affecting diagnosis of hypovascular liver metastases. Characterization of benign lesions, however, is impaired at DL75, which may lead to unnecessary follow-up examinations. Finally, increased image noise seems to affect the detection of small lesions to a degree that cannot be explained solely by the reduction in CNR.
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| 8. |
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| 9. |
- Bach-Gansmo, T, et al.
(författare)
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Motion associated susceptibility artifacts
- 1992
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Ingår i: Acta Radiologica. - 1600-0455. ; 33:6, s. 606-610
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Tidskriftsartikel (refereegranskat)abstract
- A bowel labeling agent is important for improving abdominal MR. Besides providing contrast between the bowel and other organs, the contrast agent itself is a potential source of artifacts. The artifacts created by superparamagnetic particles (SPP) subjected to motion have been studied in vitro at 0.5 T, and compared to artifacts created by a paramagnetic compound. Apart from the expected static effects of the SPP, movement induced additional artifacts were seen as signal displacements in the phase-encoding direction. The artifacts were obvious at an iron concentration of 1 mg Fe/ml, barely visible at 0.2 mg Fe/ml, and completely absent at 0.1 mg Fe/ml. Artifacts were also evident with the SPP outside the imaging slice. This further emphasizes the importance of choosing the lowest effective dose when using SPP contrast agents. For the paramagnetic agent, motion propagated artifacts consisted of high and low signal regions in a mosaic pattern.
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| 10. |
- Cronberg, Carin, et al.
(författare)
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Peripheral arterial disease.
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 44:1, s. 59-66
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Tidskriftsartikel (refereegranskat)
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