Post-contrast 3D T1-weighted TSE MR sequences (SPACE, CUBE, VISTA/BRAINVIEW, isoFSE, 3D MVOX): Technical aspects and clinical applications.

Post-contrast three-dimensional T1-weighted imaging of the brain is widely used for a broad range of vascular, inflammatory or tumoral diseases. The variable flip angle 3D TSE sequence is now available from several manufacturers (CUBE, General Electric; SPACE, Siemens; VISTA/BRAINVIEW, Philips; isoFSE, Itachi; 3D MVOX, Canon). Compared to gradient-echo (GRE) techniques, 3D TSE offers the advantages of useful image contrasts and reduction of artifacts from static field inhomogeneity. However, the respective role of 3D TSE and GRE MR sequences remains to be elucidated, particularly in the setting of post-contrast imaging. The purpose of this review was (1) to describe the technical aspects of 3D TSE sequences, (2) to illustrate the main clinical applications of the post-contrast 3D T1-w TSE sequence through clinical cases, (3) to discuss the respective role of post-contrast 3D TSE and GRE imaging in the field of neuroimaging.

DWI-ASPECTS (Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Scores) and DWI-FLAIR (Diffusion-Weighted Imaging-Fluid Attenuated Inversion Recovery) Mismatch in Thrombectomy Candidates: An Intrarater and Interrater Agreement Study.

BACKGROUND AND PURPOSE: We aimed to study the intrarater and interrater agreement of clinicians attributing DWI-ASPECTS (Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Scores) and DWI-FLAIR (Diffusion-Weighted Imaging-Fluid Attenuated Inversion Recovery) mismatch in patients with acute ischemic stroke referred for mechanical thrombectomy. METHODS: Eighteen raters independently scored anonymized magnetic resonance imaging scans of 30 participants from a multicentre thrombectomy trial, in 2 different reading sessions. Agreement was measured using Fleiss κ and Cohen κ statistics. RESULTS: Interrater agreement for DWI-ASPECTS was slight (κ=0.17 [0.14-0.21]). Four raters (22.2%) had a substantial (or higher) intrarater agreement. Dichotomization of the DWI-ASPECTS (0-5 versus 6-10 or 0-6 versus 7-10) increased the interrater agreement to a substantial level (κ=0.62 [0.48-0.75] and 0.68 [0.55-0.79], respectively) and more raters reached a substantial (or higher) intrarater agreement (17/18 raters [94.4%]). Interrater agreement for DWI-FLAIR mismatch was moderate (κ=0.43 [0.33-0.57]); 11 raters (61.1%) reached a substantial (or higher) intrarater agreement. CONCLUSIONS: Agreement between clinicians assessing DWI-ASPECTS and DWI-FLAIR mismatch may not be sufficient to make repeatable clinical decisions in mechanical thrombectomy. The dichotomization of the DWI-ASPECTS (0-5 versus 0-6 or 0-6 versus 7-10) improved interrater and intrarater agreement, however, its relevance for patients selection for mechanical thrombectomy needs to be validated in a randomized trial.

Can MRI quantification help evaluate stroke age?

BACKGROUND: Diffusion-weighted imaging (DWI) fluid-attenuated inversion recovery (FLAIR) mismatch has a proven ability to estimate stroke-to-magnetic resonance imaging (MRI) delay. We evaluated the possibility of enhancing this estimation by quantifying MRI (DWI and FLAIR) signals, and compared this approach to the visual evaluation of DWI-FLAIR mismatch. MATERIALS AND METHODS: This retrospective study included 194 patients presenting an ischemic stroke in the middle cerebral artery territory that had been explored with 3T MRI within 12h. According to the study design, written informed consent was waived and patient information was anonymized and de-identified prior to analysis. DWI-FLAIR mismatch was visually estimated by two radiologists and a quantification of MRI signals based on a manual segmentation of stroke lesion volume was performed. Using their receiver operating curve and area under the curve (AUC), we identified the variables of MRI quantification that were predictive of stroke-to-MRI delay, then compared their performance against visual classification. RESULTS: The quantitative variables identified as predictive of stroke-to-MRI delay were: 1st quartile, 3rd quartile and median values of B0; 1st quartile, 3rd quartile, median and relative values of B1000; 1st quartile and relative values of the apparent diffusion coefficient. FLAIR was not found to be predictive. The AUC values of these variables ranged between 0618±0.053 and 0.683±0.048. The relative value of B1000 appeared to be the best predictive quantitative variable, with predictive values comparable to visual classification. CONCLUSIONS: The quantification of MRI signal may be a helpful tool for stroke dating but cannot outperform the visual estimation of stroke lesion age.

Rebleeding of a neck remnant in a case of ruptured aneurysm initially treated with coils.

The follow-up and indications for retreatment of intracranial aneurysms treated endovascularly are still a matter of debate. We report the case of a patient with a ruptured aneurysm who was treated twice with coils and regularly followed up with MRI/MR angiography which showed a neck remnant that finally rebled.

Detection of aneurysmal subarachnoid hemorrhage 3†months after initial bleeding: evaluation of T2* and FLAIR MR sequences at 3†T in comparison with initial non-enhanced CT as a gold standard.

OBJECTIVE: To investigate the ability of T2* and fluid-attenuated inversion recovery (FLAIR) MR sequences to detect hemosiderin deposition 3 months after aneurysmal subarachnoid hemorrhage (SAH) in comparison with early non-enhanced CT (NECT) as a gold standard. MATERIALS AND METHODS: From September 2008 through May 2013, patients with aneurysmal SAH were included if a NECT less than 24 h after the onset of symptoms showed a SAH, and MRI, including T2* and FLAIR sequences, was performed 3 months later. All aneurysms were treated endovascularly. NECT and MR sequences were blindly analyzed for the presence of SAH (NECT) or hemosiderin deposition (MRI). When positive, details of the spatial distribution of SAH or hemosiderin deposits were noted. Sensitivities were calculated for each patient. Sensitivities, specificities, and positive predictive values (PPVs) were calculated for each location. RESULTS: Forty-nine patients (mean age 52.9 years) were included. Bleeding-related patterns were identified in 43 patients (87.8%) on T2* and 10 patients (20.4%) on FLAIR. T2* was highly predictive of the location of the initial hemorrhage, especially in the Sylvian cisterns (PPVs 95% and 100%) and the anterior interhemispheric fissure (PPV 90%). CONCLUSIONS: The T2* sequence can detect and localize a previous SAH a few months after aneurysmal bleeding.

Follow-up of intracranial aneurysms treated by flow diverter: comparison of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MR angiography (CE-MRA) sequences with digital subtraction angiography as the gold standard.

BACKGROUND AND PURPOSE: Follow-up of intracranial aneurysms treated by flow diverter with MRI is complicated by imaging artifacts produced by these devices. This study compares the diagnostic accuracy of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3 T for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment, with digital subtraction angiography (DSA) as the gold standard. MATERIALS AND METHODS: Patients treated with flow diverters between January 2009 and January 2013 followed by MRA at 3 T (3D-TOF-MRA and CE-MRA) and DSA within a 48 h period were included in a prospective single-center study. Aneurysm occlusion was assessed with full and simplified Montreal scales and parent artery patency with three-grade and two-grade scales. RESULTS: Twenty-two patients harboring 23 treated aneurysms were included. Interobserver agreement using simplified scales for occlusion (Montreal) and parent artery patency were higher for DSA (0.88 and 0.61) and CE-MRA (0.74 and 0.55) than for 3D-TOF-MRA (0.51 and 0.02). Intermodality agreement was higher for CE-MRA (0.88 and 0.32) than for 3D-TOF-MRA (0.59 and 0.11). CE-MRA yielded better accuracy than 3D-TOF-MRA for aneurysm remnant detection (sensitivity 83% vs 50%; specificity 100% vs 100%) and for the status of the parent artery (specificity 63% vs 32%; sensitivity 100% vs 100%). CONCLUSIONS: At 3 T, CE-MRA is superior to 3D-TOF-MRA for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment. However, intraluminal evaluation remains difficult with MRA regardless of the sequence used.

Rebleeding of a neck remnant in a case of ruptured aneurysm initially treated with coils.

The follow-up and indications for retreatment of intracranial aneurysms treated endovascularly are still a matter of debate. We report the case of a patient with a ruptured aneurysm who was treated twice with coils and regularly followed up with MRI/MR angiography which showed a neck remnant that finally rebled.

Endovascular treatment with flow diverters of recanalized and multitreated aneurysms initially treated by endovascular approach.

PURPOSE: To evaluate the feasibility, safety and efficacy of endovascular treatment with flow diverters in patients with recanalized and multitreated aneurysms in a retrospective, multicenter, single-arm study. METHODS: The study included 29 patients with 29 recanalized aneurysms who were treated by flow diverters (Silk or Pipeline devices). Pre- and post-procedural complications and morbidity and mortality rates were evaluated and functional outcomes (modified Rankin Score (mRS)) at 1 month (short-term) and 3-4 months (mid-term) were compared with preoperative mRS (before the procedure). Mid-term angiographic follow-up was performed assessing aneurysmal occlusion by the Montreal scale (complete occlusion, neck remnant, aneurysm remnant). RESULTS: Placement of the flow diverters was achieved in all patients. Two misdeployments of the flow diverters necessitated balloon dilation in two patients, which was associated with stent delivery in one patient. Permanent morbidity related to treatment was 6.9% (2/29), transient morbidity was 10.3% (3/29) and there were no deaths resulting from the treatment. One patient died from a myocardial infarct 4 weeks after the procedure. 25/29 patients (86.2%) had a good final functional outcome, 26/29 (89.7%) had an unchanged functional outcome and 2/29 patients (6.9%) had clinical worsening. Angiographic follow-up showed complete occlusion in 17/28 patients (60.7%), neck remnants in 6/28 patients (21.4%) and residual aneurysms in 5/28 (17.9%). CONCLUSIONS: Flow diverter placement is feasible and safe in patients with recanalized and multitreated aneurysms. The procedure is associated with a high percentage of good functional outcomes as well as good mid-term anatomical results (82.1%).

Analysis of recanalization after endovascular treatment of intracranial aneurysm (ARETA trial): presentation of a prospective multicenter study.

PURPOSE: Aneurysm recanalization is a main concern after endovascular treatment of intracranial aneurysms. But to date, no systematic analysis of the risk factors affecting its occurrence has been conducted in a large series of patients. Analysis of Recanalization after Endovascular Treatment of intracranial Aneurysm (ARETA) is a multicenter, prospective trial whose aim is to collect a large series of patients treated endovascularly to analyze factors affecting aneurysm recanalization. STUDY DESIGN: Patients with ruptured or unruptured aneurysms treated endovascularly will be enrolled from December 2013 to December 2014 in 19 participating centers in France. Patient and aneurysm characteristics will be recorded as well as the type of endovascular treatment and the occurrence of procedural or post-procedural complications. Post-procedural and follow-up imaging after one year will be analyzed independently by two readers using a 3-grade scale (complete occlusion, neck remnant, or aneurysm remnant). The progression of aneurysm occlusion will also be evaluated (improved, stable, or worsened). Aneurysm occlusion at one year and progression of aneurysm occlusion will be analyzed in light of patient, aneurysm, and treatment factors. CONCLUSION: ARETA is a large, prospective, multicenter trial designed to assess predictive factors of aneurysm recanalization after endovascular treatment of intracranial aneurysms.

Delayed ipsilateral parenchymal hemorrhage following treatment of intracranial aneurysms with flow diverter.

INTRODUCTION: The use of flow diverters (FDs) has shown promising results, particularly in the treatment of large or complex intracranial aneurysms. However, some complications can occur both during and after FD treatment, including delayed ipsilateral parenchymal hemorrhage (DIPH). The clinical presentation, etiopathogeny, and management of this complication are not well understood. We report a series of four patients with DIPH and discuss the potential mechanisms and modalities of treatment. METHODS: Four patients treated with FDs and presenting with DIPH were diagnosed in two different centers. Clinical and imaging data were reviewed before and after the procedure. Characteristics of the intraparenchymal hematomas, the modalities of treatment, and clinical course were analyzed. RESULTS: Intraparenchymal hemorrhage occurred 1 to 4 days after aneurysm treatment with FDs. All hemorrhages were situated in the ipsilateral hemisphere and were anatomically remote from the treated aneurysm. The four patients were treated with emergency surgery (hematoma evacuation). All patients had a favorable clinical outcome (mRS = 1) at midterm evaluation. Follow-up imaging showed good permeability of the FD in all subjects and complete aneurysm occlusion in all patients. CONCLUSION: From the literature review, DIPH appears to be more frequent than delayed aneurysm rupture and may be a cause of increasing concern for the use of flow diverters. However, the mechanisms of DIPH are not completely understood. Surgical evacuation of the hematoma seems to be feasible with acceptable safety and good clinical outcomes.

Multimodality imaging of melanoma metastases to the abdomen and pelvis.

Disease in the abdomen and pelvis is frequent in patients with metastatic melanoma (MM). Multidetector row computed tomography is the imaging modality of choice for diagnosis and follow-up of MM. However, positron emission tomographic scan may be used as well as other newer imaging modalities, particularly for imaging of the abdominal and pelvic metastases. The aim if this exhibit is to review the distribution and features of melanoma metastases to the abdomen and pelvis as well as the role of currently available imaging modalities.