Leptomeningeal enhancement on post-contrast FLAIR images for early diagnosis of Susac syndrome.

BACKGROUND: Leptomeningeal enhancement (LME) is a key feature of Susac syndrome (SuS) but is only occasionally depicted on post-contrast T1-weighted images (T1-WI). OBJECTIVE: As post-contrast fluid-attenuated inversion recovery (FLAIR) may be more sensitive, our aim was to assess LME in SuS on this sequence. METHODS: From 2010 to 2020, 20 patients with definite SuS diagnosis were retrospectively enrolled in this multicentre study. Two radiologists independently assessed the number of LME on post-contrast FLAIR and T1-WI acquisitions performed before any treatment. A chi-square test was used to compare both sequences and the interrater agreement was calculated. RESULTS: Thirty-five magnetic resonance imagings (MRIs) were performed before treatment, including 19 post-contrast FLAIR images in 17 patients and 25 post-contrast T1-WI in 19 patients. In terms of patients, LME was observed on all post-contrast FLAIR, contrary to post-contrast T1-WI (17/17 (100%) vs. 15/19 (79%), p < 0.05). In terms of sequences, LME was observed on all post-contrast FLAIR, contrary to post-contrast T1-WI (19/19 (100%) vs. 16/25 (64%), p < 0.005). LME was disseminated at both supratentorial (19/19) and infratentorial (18/19) levels on post-contrast FLAIR, contrary to post-contrast T1-WI (3/25 and 9/25, respectively). Interrater agreement was excellent for post-contrast FLAIR (κ = 0.95) but only moderate for post-contrast T1-WI (κ = 0.61). CONCLUSION: LME was always observed and easily visible on post-contrast FLAIR images prior to SuS treatment. In association with other MRI features, it is highly indicative of SuS.

Reproducibility of volume analysis of dynamic susceptibility contrast perfusion-weighted imaging in untreated glioblastomas.

PURPOSE: Despite a high variability, the hotspot method is widely used to calculate the cerebral blood volume (CBV) of glioblastomas on DSC-MRI. Our aim was to investigate inter- and intra-observer reproducibility of parameters calculated with the hotspot or a volume method and that of an original parameter assessing the fraction of pixels in the tumour volume displaying rCBV > 2: %rCBV > 2. METHODS: Twenty-seven consecutive patients with untreated glioblastoma (age: 63, women: 11) were retrospectively included. Three observers calculated the maximum tumour CBV value (rCBVmax) normalized with a reference ROI in the contralateral white matter (CBVWM) with (i) the hotspot method and (ii) with a volume method following tumour segmentation on 3D contrast-enhanced T1-WI. From this volume method, %rCBV > 2 was also assessed. After 8-12 weeks, one observer repeated all delineations. Intraclass (ICC) and Lin's (LCC) correlation coefficients were used to determine reproducibility. RESULTS: Inter-observer reproducibility of rCBVmax was fair with the hotspot and good with the volume method (ICC = 0.46 vs 0.65, p > 0.05). For CBVWM, it was fair with the hotspot and excellent with the volume method (0.53 vs 0.84, p < 0.05). Reproducibility of one pairwise combination of observers was significantly better for both rCBVmax and CBVWM (LCC = 0.33 vs 0.75; 0.52 vs 0.89, p < 0.05). %rCBV > 2 showed excellent inter- and intra-observer reproducibility (ICC = 0.94 and 0.91). CONCLUSION: Calculated in glioblastomas with a volume method, rCBVmax and CBVWM yielded good to excellent reproducibility but only fair with the hotspot method. Overall, the volume analysis offers a highly reproducible parameter, %rCBV > 2, that could be promising during the follow-up of such heterogeneous tumours.

Risk of Intracerebral Hemorrhage and Mortality After Convexity Subarachnoid Hemorrhage in Cerebral Amyloid Angiopathy.

Background and Purpose- Convexity subarachnoid hemorrhage (cSAH) is an increasingly recognized presentation of cerebral amyloid angiopathy (CAA), usually revealed by transient symptoms, but data on its outcome are limited. We compared the risk of future intracerebral hemorrhage (ICH), cSAH, and death in patients with CAA after cSAH and after lobar ICH. Methods- Consecutive patients with probable CAA, based on the Boston criteria, presenting with cSAH (CAA-cSAH) or lobar ICH (CAA-ICH) were included. We obtained baseline clinical and magnetic resonance imaging data and follow-up information. Univariable and multivariable analyses were used to compare incidence rate for symptomatic ICH, symptomatic cSAH, and late-death (beyond 30 days) between patients with CAA-cSAH and CAA-ICH. Results- Among 105 patients (mean age, 76.7±7.5 years) enrolled, 44 participants presented with CAA-cSAH and 61 with CAA-ICH. The median follow-up was 22.2 months (interquartile range, 12.6-34.4). The symptomatic ICH rate (per person-year) was 10.5% (95% CI, 5.6-19.4) in patients with CAA-cSAH compared with 8.5% (95% CI, 4.4-16.4) in those with CAA-ICH (adjusted hazard ratio, 1.05; 95% CI, 0.32-3.43). The annual incidence rates of symptomatic cSAH (9.9% versus 3.8%; adjusted hazard ratio, 1.77; 95% CI, 0.43-7.28) and death (9.5% versus 17.8%; adjusted hazard ratio, 0.56; 95% CI, 0.22-1.43) were not significantly different between patients with CAA-cSAH and those with CAA-ICH. Conclusions- Patients with CAA-related cSAH have a poor outcome, with similar high risk of future ICH and long-term mortality than CAA patients after lobar ICH. Our findings may have important prognostic implication and guide management of patients with cSAH in CAA.

Subarachnoid and Subdural Hemorrhages in Lobar Intracerebral Hemorrhage Associated With Cerebral Amyloid Angiopathy.

Background and Purpose- Identifying underlying cerebral amyloid angiopathy (CAA) in patients with intracerebral hemorrhage (ICH) has important clinical implication. Convexity subarachnoid hemorrhage (cSAH) and subdural hemorrhage (SDH) are computed tomography features of CAA-related ICH. We explored whether cSAH and SDH could be additional magnetic resonance imaging markers of CAA in lobar ICH survivors. Methods- We analyzed data from consecutive patients with acute lobar ICH associated with CAA (CAA-ICH) or not attributed to CAA (non-CAA-ICH). Magnetic resonance imaging scans were analyzed for cSAH, SDH, and markers of small vessel disease. The associations of cSAH and SDH with the diagnosis of probable CAA based on the modified Boston criteria were explored using multivariable models. Results- We included 165 patients with acute lobar ICH (mean age 70±13 years): 72 patients with CAA-ICH and 93 with non-CAA-ICH. Patients with CAA-ICH had a higher prevalence of cSAH (73.6% versus 39.8%; P<0.001) and SDH (37.5% versus 21.5%; P=0.02) than non-CAA-ICH. In multivariate logistic regression analysis, the presence of cSAH was independently associated with CAA-ICH (odds ratio, 2.97; 95% CI, 1.26-6.99; P=0.013), whereas there was no association between SDH and CAA-ICH. Conclusions- Among survivors of acute lobar ICH, the presence of cSAH is associated with the magnetic resonance imaging-based diagnosis of CAA. Further studies should investigate whether cSAH help improve the sensitivity of magnetic resonance imaging for in vivo diagnosis of CAA.

MRI features of demyelinating disease associated with anti-MOG antibodies in adults.

The spectrum of Myelin Oligodendrocytes Glycoprotein (MOG) antibody disease constitutes a recently described challenging entity, referring to a relatively new spectrum of autoimmune disorders with antibodies against MOG predominantly involving the optic nerve and spinal cord. The purpose of this article is to describe MRI features of MOG-AD involvement in the optic nerves, spinal cord and the brain of adults.

Osteoid osteomas in common and in technically challenging locations treated with computed tomography-guided percutaneous radiofrequency ablation.

OBJECTIVE: To evaluate the efficacy of computed tomography (CT)-guided radiofrequency (RF) ablation for the treatment of osteoid osteomas in common and in technically challenging locations. MATERIALS AND METHODS: Twenty-three patients with osteoid osteomas in common (nine cases) and technically challenging [14 cases: intra-articular (n = 7), spinal (n = 5), metaphyseal (n = 2)] positions were treated with CT-guided RF ablation. Therapy was performed under conscious sedation with a seven-array expandable RF electrode for 8-10 min at 80-110 degrees C and power of 90-110 W. The patients went home under instruction. A brief pain inventory (BPI) score was calculated before and after (1 day, 4 weeks, 6 months and 1 year) treatment. RESULTS: All procedures were technically successful. Primary clinical success was 91.3% (21 of total 23 patients), despite the lesions' locations. BPI score was dramatically reduced after the procedure, and the decrease in BPI score was significant (P < 0.001, paired t-test; n-1 = 22) for all periods during follow up. Two patients had persistent pain after 1 month and were treated successfully with a second procedure (secondary success rate 100%). No immediate or delayed complications were observed. CONCLUSION: CT-guided RF ablation is safe and highly effective for treatment of osteoid osteomas, even in technically difficult positions.

What is the Relevance of the Systematic Use of Gadolinium During the MRI Follow-Up of Multiple Sclerosis Patients Under Natalizumab?

BACKGROUND: Multiple sclerosis (MS) patients represent a population potentially affected by the intracerebral accumulation of gadolinium-based contrast agents (GBCA) due to repeated magnetic resonance imaging (MRI) performed during their lifetime; however, MRI is still the best tool to monitor MS inflammatory activity. OBJECTIVE: This study aimed to evaluate the relevance of GBCA injections during the MRI follow-up of MS patients under natalizumab (Tysabri) treatment. METHODS: The MRI data results were retrospectively reviewed in a monocentric study (University Hospital of Toulouse, France) from all consecutive patients treated with natalizumab from January 2014 to January 2017. For each examination during the whole MRI follow-up, new lesions (enhancing and non-enhancing) were analyzed. RESULTS: A total of 129 patients were included in this study (65% female, mean age = 41 years, mean treatment duration 6.5 years, 50% positive for John Cunningham virus) and benefited from 735 MRIs with GBCA. Only 3 MRIs showed a new enhancing lesion, systematically encountered after treatment discontinuation. CONCLUSION: According to this study based on the clinical and radiological practice, the systematic use of GBCA seems of limited relevance in the MRI follow-up of asymptomatic patients treated continuously with natalizumab.

Magnetic resonance imaging of arterial stroke mimics: a pictorial review.

Acute ischaemic stroke represents the most common cause of new sudden neurological deficit, but other diseases mimicking stroke happen in about one-third of the cases. Magnetic resonance imaging (MRI) is the best technique to identify those 'stroke mimics'. In this article, we propose a diagnostic approach of those stroke mimics on MRI according to an algorithm based on diffusion-weighted imaging (DWI), which can be abnormal or normal, followed by the results of other common additional MRI sequences, such as T2 with gradient recalled echo weighted imaging (T2-GRE) and fluid-attenuated inversion recovery (FLAIR). Analysis of the signal intensity of the parenchyma, the intracranial arteries and, overall, of the veins, is crucial on T2-GRE, while anatomic distribution of the parenchymal lesions is essential on FLAIR. Among stroke mimics with abnormal DWI, T2-GRE demonstrates obvious abnormalities in case of intracerebral haemorrhage or cerebral amyloid angiopathy, but this sequence also allows to propose alternative diagnoses when DWI is negative, such as in migraine aura or headaches with associated neurological deficits and lymphocytosis (HaNDL), in which cortical venous prominence is observed at the acute phase on T2-GRE. FLAIR is also of major interest when DWI is positive by better showing evocative distribution of cerebral lesions in case of seizure (involving the hippocampus, pulvinar and cortex), hypoglycaemia (bilateral lesions in the posterior limb of the internal capsules, corona radiata, striata or splenium of the corpus callosum) or in posterior reversible encephalopathy syndrome (PRES). Other real stroke mimics such as mitochondrial myopathy, encephalopathy, lactic acidosis, stroke-like episodes (MELAS), Susac's syndrome, brain tumour, demyelinating diseases and herpes simplex encephalitis are also included in our detailed and practical algorithm. KEY POINTS: • About 30% of sudden neurological deficits are due to non-ischaemic causes. • MRI is the best technique to identify stroke mimics. • Our practical illustrated algorithm based on DWI helps to recognise stroke mimics.

Palliative treatment of rectal carcinoma recurrence using radiofrequency ablation.

PURPOSE: To evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation for the palliative treatment of recurrent unresectable rectal tumors. MATERIALS AND METHODS: Twenty-seven patients with locally recurrent rectal cancer were treated with computed tomography (CT)-guided RF ablation. Therapy was performed with the patient under conscious sedation with a seven- or a nine-array expandable RF electrode for 8-10 min at 80-110°C and a power of 90-110 W. All patients went home under instructions the next day of the procedure. Brief Pain Inventory score was calculated before and after (1 day, 1 week, 1 month, 3 months, and 6 months) treatment. RESULTS: Complete tumor necrosis rate was 77.8% (21 of a total 27 procedures) despite lesion location. BPI score was dramatically decreased after the procedure. The mean preprocedure BPI score was 6.59, which decreased to 3.15, 1.15, and 0.11 at postprocedure day 1, week 1, and month 1, respectively, after the procedure. This decrease was significant (p < 0.01 for the first day and p < 0.001 for the rest of the follow-up intervals (paired Student t test; n - 1 = 26) for all periods during follow-up. Six patients had partial tumor necrosis, and we were attempted to them with a second procedure. Although the necrosis area showed a radiographic increase, no complete necrosis was achieved (secondary success rate 65.6%). No immediate or delayed complications were observed. CONCLUSION: CT-guided RF ablation is a minimally invasive, safe, and highly effective technique for treatment of malignant rectal recurrence. The method is well tolerated by patients, and pain relief is quickly achieved.