Follow-Up of Coiled Cerebral Aneurysms at 3T: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography

BACKGROUND AND PURPOSE: Our aim was to compare contrast-enhanced MR angiography (CE-MRA) and 3D time-of-flight (TOF) MRA at 3T for follow-up of coiled cerebral aneurysms. MATERIALS AND METHODS: Fifty-two patients treated with Guglielmi detachable coils for 54 cerebral aneurysms were evaluated at 3T MRA. 3D TOF MRA (TR/TE = 23/3.5; SENSE factor = 2.5) and CE-MRA by using a 3D ultrafast gradient-echo sequence (TR/TE = 5.9/1.8; SENSE factor = 3) enhanced with 0.1-mmol/kg gadobenate dimeglumine were performed in the same session. Source images, 3D maximum intensity projection, 3D shaded surface display, and/or 3D volume-rendered reconstructions were evaluated in terms of aneurysm occlusion/patency and artifact presence. RESULTS: In terms of clinical classification, the 2 MRA sequences were equivalent for 53 of the 54 treated aneurysms: 21 were considered fully occluded, whereas 16 were considered to have a residual neck and 16 were considered residually patent at follow-up MRA. The remaining aneurysm appeared fully occluded at TOF MRA but had a residual patent neck at CE-MRA. Visualization of residual aneurysm patency was significantly ( P = .001) better with CE-MRA compared with TOF MRA for 10 (31.3%) of the 32 treated aneurysms considered residually patent with both sequences. Coil artifacts were present in 5 cases at TOF MRA but in none at CE-MRA. No relationship was apparent between the visualization of patency and either the size of the aneurysm or the interval between embolization and follow-up. CONCLUSION: At follow-up MRA at 3T, unenhanced TOF and CE-MRA sequences are similarly effective at classifying coiled aneurysms as occluded or residually patent. However, CE-MRA is superior to TOF MRA for visualization of residual patency and is associated with fewer artifacts

Mycotic aortic aneurysm presenting as multiple cerebral abscesses

A 68-year-old male presented with multiple cerebral abscesses. Possible intrathoracic embolic sources were not detected by echocardiography and chest radiography and the main lesion was surgically excised. Following deterioration of the neurological status, computerized tomography performed 2 weeks later revealed a mycotic aneurysm of the ascending aorta, probably related to a previous cardiac operation. This is the first case in the literature of aortic infection presenting as multiple brain abscesses

Debunking 7 myths that hamper the realization of randomized controlled trials on intra-arterial thrombolysis for acute ischemic stroke.

Background and Purpose—Although intravenous (IV) thrombolysis is the standard treatment for patients with ischemic stroke occurring within 3 hours from symptom onset, a few interventional neuroradiologists have been treating this category of patients by an intra-arterial (IA) route for 25 years. However, evidence is still required to support the clinical feeling that IA treatment, which needs longer time and greater complexity, leads to a better outcome. Therefore, the objective of the present review was to analyze beliefs and myths underlying the selection of patients for IA thrombolysis. Methods and Results—We identified and debunked the following myths on IA thrombolysis: (1) IA thrombolysis works better than IV because it achieves higher recanalization rates; (2) IA thrombolysis works better than IV after the 3-hour window; (3) IA thrombolysis works better than IV in vertebrobasilar stroke; (4) carotid duplex, transcranial doppler, CT angiography, or MRA should be used to screen for major vessel occlusion treatable with IA thrombolysis; (5) to be treated with IA thrombolysis, patients should be selected with diffusion/perfusion MRI; (6) IA thrombolysis should be used as a “rescue” therapy for IV thrombolysis; and (7) the efficacy of IA thrombolysis depends on the thrombolytic agent or the device used. Conclusion—Evidence on acute stroke management with IA thrombolysis is scant. Therefore, neither clinicians nor patients have enough information to make truly informed decisions about the most appropriate treatment. Only randomized controlled trials can clear uncertainties about the possible superiority of IA over IV thrombolysis. Regretfully, case series on IA treatment have limited the organization of such trials and have only favored the spread of myths

Firing pin impressions: a valuable feature for determining the orientation of the weapon at the time of shooting

Sometimes the firearm forensic examiner is required to provide information useful to discriminate between suicide, homicide or accident, or between contradictory reconstructions of the events (like attempted murder versus accidental discharge). In such situations, knowledge of the position and orientation of the firearm at the time of firing can be of fundamental help for the reconstruction of events. To achieve these goals, the analysis of the firing impressions is very important. In this study, the cartridge cases shot with three different revolvers aiming at three different spatial orientations (vertical upwards, horizontal or vertical downwards) were studied. The depth and morphology of the firing pin impression was characterised by optical microscopy and quantified by a surface topography analysis. The orientation of the firearm significantly modified the morphology and depth of the firing pin impression: ammunition fired upwards had the deepest firing pin impression, those fired downwards had the shallowest. Such behaviour was attributed to the different geometry of the firing pin-primer cup interaction and to the different pressure exerted by the primer as the orientation of the weapon changes. Therefore, this work has shown that a suitable protocol of morphological and topographical analysis can be set up to understand if a shot by a revolver was fired holding the weapon upwards, downwards or horizontally

Comparison of 3D TOF-MRA and 3D CE-MRA at 3T for imaging of intracranial aneurysms.

Background: Risks and complications associated with the treatment of intracranial aneurysms have decreased with the growing use of less in- vasive endovascular techniques. Nevertheless, some risk remains and must be balanced with the risk of aneurysm rupture. Both the risk of rupture and selection of treatment are largely based on factors related to specific characteristics of the particular aneurysm obtained from imaging examinations. Because magnetic resonance angiography (MRA) is noninvasive, lacks use of ionizing radiation, and is less costly, it is largely replacing conventional angiography for the diagnosis and follow-up of intracranial aneurysms. Studies have shown that nonenhanced 3D time-of-flight- (TOF-) MRA is satisfactory for follow-up of aneurysms, and that TOF-MRA performed at 3T provides improved depiction of aneu- rysms compared to 1.5T. Whether the use of MRA with gadolinium contrast provides any added benefit is less clear, with some studies showing that 3D contrast-enhanced MRA (CE-MRA) is better for visualizing aneurysmal morphology, while other studies have shown no such benefit, particularly at 3T. Here we compare 3D TOF-MRA and 3D CE-MRA, both at 3T, for their ability to provide detailed characterization of intracranial aneurysms. Methods: Twenty-nine patients (12 male; 17 female) with known or suspected intracranial aneurysms underwent both unenhanced and contrast-enhanced MRA using an In- tera 3 Tesla magnet (Philips Medical Systems, The Netherlands) with an 8-channel SENSE head coil in a single session. The unenhanced acquisition was carried out with a 3D TOF-MRA sequence (3D FFE, TR 2.3, TE 3.5, FOV 250, matrix 1024x1024, SENSE factor 2.5, 180 slice, 4 chunk, voxel size 0.5x0.5x1 mm), focused on the Circle of Willis and carried out in the axial plane, with fat suppression. Con- trast-enhanced images were acquired with a 3D ultrafast FE sequence (TR 5.9, TE 1.8, FOV 220, matrix 304, re- construction 512, SENSE factor 3, 80 slice, voxel size 0.72x0.72x0.80 mm) in the axial plane, focused on the an- eurysm, using CENTRA for k-space elliptical mapping. A total dose of 0.1 mmol/kg gadobenate dimeglumine (MultiHance; Bracco SpA, Italy) was injected at 2 mL/sec, followed by a 25- mL saline flush injected at the same rate. Both maximum intensity projec- tion (MIP) and volume rendering (VR) techniques were used for image analy- sis. The following features were com- pared for the 2 imaging techniques: the location and length of the aneu- rysm, the sac shape, the presence and measurement of the aneurysm neck, the detection of arterial branches orig- inating from the sac or the neck of the aneurysm, and any other associated circulatory abnormalities. Results: A total of 41 aneurysms were identified with both TOF-MRA and CE-MRA techniques: 20 in the in- ternal carotid artery, 10 vertebrobasi- lar, 7 in the anterior communicating artery, and 4 in the middle cerebral artery. There were no differences be- tween the techniques in terms of detec- tionoftheaneurysms,location,oridentification of the parent artery. There were no differences between TOF-MRA and CE-MRA in terms of assessment of the aneurysm dimensions: 23 were 24 mm. TOF-MRA data detected 12 aneurysms with an irregular sac, whereas CE-MRA acqui- sitions detected 19 irregularly-shaped aneurysms. Both imaging techniques identified 5 fusiform aneurysms with no neck. Of the remaining 36 aneu- rysms, TOF-MRA reconstructions did not enable detection of the neck and therefore, did not permit measurement of the sac/neck ratio, in 10 aneurysms. With CE-MRA, the neck was detected and measured in all 36 nonfusiform aneurysms, permitting calculation of the sac/neck ratio. CE-MRA detected 15 aneurysms with branches origi- nating from the sac and/or the neck, whereas the TOF-MRA sequence ena- bled recognition of branches in only 12 of the 15 aneurysms. Finally, of the 41 aneurysms investigated, abnormali- ties of the Circle of Willis were found in 4 aneurysms with both imaging techniques. In 3 cases, A1 aplasia was found, and in the fourth case, TOF- MRA and CE-MRA both documented aplasia of the left posterior communi- cating artery. The diameter of all 4 of these aneurysms was <13 mm: in 2 of them it was less than 7 mm and in the other 2 it was between 7 and 13 mm. Conclusion: 3D CE-MRA and 3D TOF-MRA at 3T are both excellent imaging techniques for determining the presence, location, and length of intracranial aneurysms. However, CE-MRA is superior to TOF-MRA for detailed visualization of certain aneu- rysmal features that impact treatment selection, including the sac shape, neck measurements, and the presence of arterial branching