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Objective: To evaluate the reproducibility of vessel wall magnetic resonance imaging (VW-MRI) in diagnosing giant cell arteritis (GCA) among groups of radiologists with varying levels of expertise., Methods: This institutional review board-approved retrospective single-center study recruited patients with suspected GCA between December 2014 and September 2021. Patients underwent 3 -T VW-MRI before temporal artery biopsy. Ten radiologists with varying levels of expertise, blinded to all data, evaluated several intracranial and extracranial arteries to assess GCA diagnosis. Interobserver reproducibility and diagnostic performance were evaluated., Results: Fifty patients (27 women and 23 men) with a mean age of 75.9 ± 9 years were included. Thirty-one of 50 (62%) had a final diagnosis of GCA.VW-MRI had an almost perfect reproducibility among expert readers (kappa = 0.93; 95% CI 0.77-1) and substantial reproducibility among all readers, junior and non-expert senior readers (kappa = 0.7; 95% CI 0.66-0.73; kappa = 0.67 95% CI 0.59-0.74; kappa = 0.65; 95% CI 0.43-0.88 respectively) when diagnosing GCA. Substantial interobserver agreement was observed for the frontal branch of superficial temporal artery. Moderate interobserver agreement was observed for the superficial temporal artery and its parietal branch, as well as ophthalmic arteries in all groups of readers. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy varied depending on the group of readers., Conclusion: VW-MRI is a reproducible and accurate imaging modality for detecting GCA, even among less-experienced readers. This study advocates for the use of VW-MRI when diagnosing GCA even in less-experienced centers., Clinical Relevance Statement: VW-MRI is a reproducible and accurate imaging modality for detecting GCA, even among less-experienced readers, and it could be used as a first-line diagnostic tool for GCA in centers with limited expertise in GCA diagnosis., Key Points: • Vessel wall magnetic resonance imaging (VW-MRI) is a reproducible and accurate imaging modality for detecting giant cell arteritis (GCA) in both extracranial and intracranial arteries. • The reproducibility of vessel wall magnetic resonance imaging for giant cell arteritis diagnosis was high among expert readers and moderate among less-experienced readers. • The use of vessel wall magnetic resonance imaging for giant cell arteritis diagnosis can be recommended even in centers with less-experienced readers., (© 2024. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To assess the impact of timing from visual symptoms' onset to diffusion-weighted (DW) 3 T MRI completion to detect ischemic changes of the optic disc and optic nerve in AION patients., Methods: This IRB-approved retrospective single-center study included 3 T MRI data from 126 patients with AION and 111 controls with optic neuritis treated between January 2015 and May 2020. Two radiologists blinded to all data individually analyzed imaging. A senior neuroradiologist resolved any discrepancies by consensus. The primary judgment criterion was the restricted diffusion of the optic disc and/or the optic nerve assessed subjectively on the ADC maps. ADC values were also measured. Spearman rank correlations were used to examine the relationships between timing from visual symptoms' onset to MRI completion and both the restricted diffusion and the ADC values., Results: One hundred twenty-six patients (47/126 [37.3%] women and 79/126 [62.7%] men, mean age 69.1 ± 13.7 years) with AION were included. Restricted diffusion of the optic disc in AION eyes was more frequent in the early MRI group than in the late MRI group: 35/49 (71.4%) eyes versus 3/83 (3.6%) eyes, p < 0.001. ADC values of the pathological optic discs and optic nerves were lower in the early MRI group than in the late MRI group: 0.61 [0.52-0.94] × 10 -3 mm 2 /s versus 1.28 [1.01-1.44] × 10 -3 mm 2 /s, p < 0.001, and 0.74 [0.61-0.88] × 10 -3 mm 2 /s versus 0.89 [0.72-1.10] × 10 -3 mm 2 /s, p < 0.001, respectively., Conclusions: DWI MRI showed good diagnostic performance to detect AION when performed early after the onset of visual symptoms., Key Points: • Restricted diffusion of the optic disc in eyes affected by AION was significantly more likely to be observed in patients who had undergone MRI within 5 days after onset of visual symptoms. • ADC values of the pathological optic discs and optic nerves were significantly lower in patients who had undergone MRI within 5 days after onset of visual symptoms of AION: 0.61 × 10 -3 mm 2 /s versus 1.28 × 10 -3 mm 2 /s, p < 0.001, and 0.74 × 10 -3 mm 2 /s versus 0.89 × 10 -3 mm 2 /s, p < 0.001, respectively. • The optimal threshold for timing from visual symptoms' onset to MRI completion to detect restricted diffusion of the optic disc and/or optic nerve was 5 days, with an AUC of 0.88 (CI 95% : 0.82-0.94)., (© 2021. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To determine the diagnostic performances of a single Dixon-T2-weighted imaging (WI) sequence compared to a conventional protocol including T1-, T2-, and fat-suppressed T2-weighted MRI at 3 T when assessing thyroid eye disease (TED)., Materials and Methods: This IRB-approved prospective single-center study enrolled participants presenting with confirmed TED from April 2015 to October 2019. They underwent an MRI, including a conventional protocol and a Dixon-T2WI sequence. Two neuroradiologists, blinded to all data, read both datasets independently and randomly. They assessed the presence of extraocular muscle (EOM) inflammation, enlargement, fatty degeneration, or fibrosis as well as the presence of artifacts. The Wilcoxon signed-rank test was used., Results: Two hundred six participants were enrolled (135/206 [66%] women, 71/206 [34%] men, age 52.3 ± 13.2 years). Dixon-T2WI was significantly more likely to detect at least one inflamed EOM as compared to the conventional set (248/412 [60%] versus 228/412 [55%] eyes; (p = 0.02). Dixon-T2WI was more sensitive and specific than the conventional set for assessing muscular inflammation (100% versus 94.7% and 71.2% versus 68.5%, respectively). Dixon-T2WI was significantly less likely to show major or minor artifacts as compared to fat-suppressed T2WI (20/412 [5%] versus 109/412 [27%] eyes, p < 0.001, and 175/412 [42%] versus 257/412 [62%] eyes, p < 0.001). Confidence was significantly higher with Dixon-T2WI than with the conventional set (2.35 versus 2.24, p = 0.003)., Conclusion: Dixon-T2WI showed higher sensitivity and specificity and showed fewer artifacts than a conventional protocol when assessing thyroid eye disease, in addition to higher self-reported confidence., Key Points: • Dixon-T2WI has better sensitivity and specificity than a conventional protocol for assessing inflamed extraocular muscles in patients with thyroid eye disease. • Dixon-T2WI shows significantly fewer artifacts than fat-suppressed T2WI. • Dixon-T2WI is faster and is associated with significantly higher self-reported reader confidence as compared to a conventional protocol when assessing inflammatory extraocular muscles.

Objective: To determine the sensitivity and specificity of high-resolution (HR) MRI for detecting signal abnormalities of cranial nerves (CN) in giant cell arteritis (GCA) patients presenting with diplopia., Methods: This IRB-approved retrospective single-center study included GCA patients who underwent 3-T HR MRI from December 2014 to January 2020. Two radiologists, blinded to all data, individually assessed for the presence of enhancement of the 3rd, 4th, and/or 6th CN on post-contrast HR imaging and high signal intensity on HR T2-WI, for signal abnormalities of extraocular muscles and the brainstem, and for inflammatory changes of the ophthalmic and extracranial arteries. A Fisher's exact test was used to compare patients with or without diplopia., Results: In total, 64 patients (42/64 (66%) women and 22/64 (34%) men, mean age 76.3 ± 8 years) were included. Of the 64 patients, 14 (21.9%) presented with diplopia. Third CN enhancement was detected in 7/8 (87.5%) patients with 3rd CN impairment, as compared to no patients with 4th or 6th CN impairment or to patients without diplopia (p < 0.001). Third CN abnormal high signal intensity on HR T2-WI was detected in 4/5 patients (80%) with 3rd CN impairment versus none of other patients (p < 0.001). Sensitivity, specificity, positive predictive value, and negative predictive value for detecting 3rd CN signal abnormalities were of 0.88, 1, 1, and 0.99 and 0.8, 1, 1, and 0.98 for post-contrast HR imaging and HR T2-WI, respectively., Conclusions: HR MRI had excellent diagnostic sensitivity and specificity when detecting signal abnormalities of the 3rd CN in GCA patients presenting with 3rd CN impairment., Key Points: • Third cranial nerve enhancement was detected in all patients with 3rd cranial nerve impairment except for one with transient diplopia. • The "check mark sign" might be useful to identify 3rd cranial nerve signal abnormalities in the orbital apex. • No signal abnormalities of the 4th or 6th cranial nerves could be detected on high-resolution MRI.

Objective: Test a practical realignment approach to compensate the technical variability of MR radiomic features., Methods: T1 phantom images acquired on 2 scanners, FLAIR and contrast-enhanced T1-weighted (CE-T1w) images of 18 brain tumor patients scanned on both 1.5-T and 3-T scanners, and 36 T2-weighted (T2w) images of prostate cancer patients scanned in one of two centers were investigated. The ComBat procedure was used for harmonizing radiomic features. Differences in statistical distributions in feature values between 1.5- and 3-T images were tested before and after harmonization. The prostate studies were used to determine the impact of harmonization to distinguish between Gleason grades (GGs)., Results: In the phantom data, 40 out of 42 radiomic feature values were significantly different between the 2 scanners before harmonization and none after. In white matter regions, the statistical distributions of features were significantly different (p < 0.05) between the 1.5- and 3-T images for 37 out of 42 features in both FLAIR and CE-T1w images. After harmonization, no statistically significant differences were observed. In brain tumors, 41 (FLAIR) or 36 (CE-T1w) out of 42 features were significantly different between the 1.5- and 3-T images without harmonization, against 1 (FLAIR) or none (CE-T1w) with harmonization. In prostate studies, 636 radiomic features were significantly different between GGs after harmonization against 461 before. The ability to distinguish between GGs using radiomic features was increased after harmonization., Conclusion: ComBat harmonization efficiently removes inter-center technical inconsistencies in radiomic feature values and increases the sensitivity of studies using data from several scanners., Key Points: • Radiomic feature values obtained using different MR scanners or imaging protocols can be harmonized by combining off-the-shelf image standardization and feature realignment procedures. • Harmonized radiomic features enable one to pool data from different scanners and centers without a substantial loss of statistical power caused by intra- and inter-center variability. • The proposed realignment method is applicable to radiomic features from different MR sequences and tumor types and does not rely on any phantom acquisition.

Objectives: To compare the diagnostic accuracy of 3D versus 2D contrast-enhanced vessel-wall (CE-VW) MRI of extracranial and intracranial arteries in the diagnosis of GCA., Methods: This prospective two-center study was approved by a national research ethics board and enrolled participants from December 2014 to October 2017. A protocol including both a 2D and a 3D CE-VW MRI at 3 T was performed in all patients. Two neuroradiologists, blinded to clinical data, individually analyzed separately and in random order 2D and 3D sequences in the axial plane only or with reformatting. The primary judgment criterion was the presence of GCA-related inflammatory changes of extracranial arteries. Secondary judgment criteria included inflammatory changes of intracranial arteries and the presence of artifacts. A McNemar's test was used to compare 2D to 3D CE-VW MRIs., Results: Seventy-nine participants were included in the study (42 men and 37 women, mean age 75 (± 9.5 years)). Fifty-one had a final diagnosis of GCA. Reformatted 3D CE-VW was significantly more sensitive than axial-only 3D CE-VW or 2D CE-VW when showing inflammatory change of extracranial arteries: 41/51(80%) versus 37/51 (73%) (p = 0.046) and 35/50 (70%) (p = 0.03). Reformatted 3D CE-VW was significantly more specific than 2D CE-VW: 27/27 (100%) versus 22/26 (85%) (p = 0.04). 3D CE-VW showed higher sensitivity than 2D CE-VW when detecting inflammatory changes of intracranial arteries: 10/51(20%) versus 4/50(8%), p = 0.01. Interobserver agreement was excellent for both 2D and 3D CE-VW MRI: κ = 0.84 and 0.82 respectively., Conclusions: 3D CE-VW MRI supported more accurate diagnoses of GCA than 2D CE-VW., Key Points: • 3D contrast-enhanced vessel-wall magnetic resonance imaging is a high accuracy, non-invasive diagnostic tool used to diagnose giant cell arteritis. • 3D contrast-enhanced vessel-wall imaging is feasible for clinicians to complete within a relatively short time, allowing immediate assessment of extra and intracranial arteries. • 3D contrast-enhanced vessel-wall magnetic resonance imaging might be considered a diagnostic tool when intracranial manifestation of GCA is suspected.

Objectives: To evaluate the prevalence of cerebral remote microhaemorrhages (RMH) and remote haematomas (RH) using magnetic resonance susceptibility-weighted imaging (SWI) among patients treated for gliomas during follow-up., Methods: We conducted a retrospective single centre longitudinal study on 58 consecutive patients treated for gliomas from January 2009 through December 2010. Our institutional review board approved this study. We evaluated the presence and number of RMH and RH found outside the brain tumour on follow-up MR imaging. We performed univariate and bivariate analyses to identify predictors for RMH and RH and Kaplan-Meier survival analysis techniques., Results: Twenty-five (43%) and four patients (7%) developed at least one RMH or RH, respectively, during follow-up. The risk was significantly higher for patients who received radiation therapy (49% and 8% versus 0%) (p = 0.02). The risk of developing RH was significantly higher in patients with at least one RMH and a high burden of RMH. The mean age of those presenting with at least one RMH or RH was significantly lower., Conclusions: RMH were common in adult survivors of gliomas who received radiation therapy and may predict the onset of RH during follow-up, mainly in younger patients., Key Points: • Brain RMH and RH are significantly more likely to occur after RT. • RMH occur in almost half of the patients treated with RT. • RMH and RH are significantly more frequent in younger patients. • RH occur only in patients with RMH.

Objectives: To evaluate repeatability of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) parameters in the orbit., Methods: From December 2015 to March 2016, 22 patients were scanned twice using an IVIM sequence with 15b values (0-2,000 s/mm 2 ) at 3.0T. Two readers independently delineated regions of interest in an orbital mass and in different intra-orbital and extra-orbital structures. Short-term test-retest repeatability and inter-observer agreement were assessed using the intra-class correlation coefficient (ICC), the coefficient of variation (CV) and Bland-Altman limits of agreements (BA-LA)., Results: Test-retest repeatability of IVIM parameters in the orbital mass was satisfactory for ADC and D (mean CV 12% and 14%, ICC 95% and 93%), poor for f and D*(means CV 43% and 110%, ICC 90% and 65%). Inter-observer repeatability agreement was almost perfect in the orbital mass for all the IVIM parameters (ICC = 95%, 93%, 94% and 90% for ADC, D, f and D*, respectively)., Conclusions: IVIM appeared to be a robust tool to measure D in orbital lesions with good repeatability, but this approach showed a poor repeatability of f and D*., Key Points: • IVIM technique is feasible in the orbit. • IVIM has a good-acceptable repeatability of D (CV range 12-25 %). • IVIM interobserver repeatability agreement is excellent (ICC range 90-95 %). • f or D* provide higher test-retest and interobserver variabilities.