Diagnosis of a Dural Arteriovenous Fistula Involving the Superior Sagittal Sinus: The MMA Sign on Routine 3D-TOF MR Angiography.

BACKGROUND AND PURPOSE: The main feeding artery of a dural arteriovenous fistula (DAVF) involving the superior sagittal sinus (SSS) is the middle meningeal artery (MMA). MMA extends continuously from the proximal part to SSS in DAVF involving SSS. It is possible to diagnose DAVF involving SSS by evaluating the proximal part of MMA on routine three-dimensional time-of-flight MR angiography (MRA). We termed the finding in an anteroposterior maximum intensity projection (MIP) image of routine MRA in which MMA was continuously visualized at the top of the imaging slab (the upper corpus callosum level) without tapering as the MMA sign. The purpose of the present study was to examine the frequency of the MMA sign on routine MRA in patients with DAVF involving SSS and control patients. MATERIALS AND METHODS: Subjects comprised 18 patients with DAVF involving SSS confirmed by angiography and 871 control subjects who underwent routine MRA. The presence of the MMA sign was retrospectively evaluated using an anteroposterior MIP image of routine MRA in patients with DAVF involving SSS and control patients. RESULTS: The MMA sign was observed in 17 of the 18 (94%) patients with DAVF involving SSS. In one patient with DAVF involving the posterior part of SSS without the MMA sign, the main feeding artery was the occipital artery, not MMA. The MMA sign was observed in 13 of the 871 (1.5%) control patients. CONCLUSION: The MMA sign on routine MRA is useful, suggesting DAVF involving SSS.

MRA-based evaluation of anatomical variation of circle of Willis in adult Pakistanis.

OBJECTIVE: To determine the frequency and patterns of normal anatomical variation of Circle of Willis on magnetic resonance angiogram in adults without cerebrovascular disease. METHODS: This descriptive cross-sectional study was conducted at the Radiology Department of Dow University of Health Sciences / Civil Hospital, Karachi, from January to December 2016, and comprised patients referred for magnetic resonance imaging of the brain and magnetic resonance angiogram without any clinical or radiological manifestation of cerebrovascular disease, primarily including those with suspected demyelination, infection, epilepsy or metastases. Three-dimensional time-of-flight magnetic resonance angiography was performed. The Circle of Willis was assessed for its completeness along with anatomical variations of anterior and posterior components of the circle. RESULTS: Of the 135 subjects, 70(51.8%) were males and 65(48.2%) were females with an overall mean age of 49.26±9.2 years. Among all the subjects, 30(22.2%) showed a complete circle, while 82 (60.7%) and 23(17.1%) had partially complete and incomplete circles respectively. The anterior part of the circle was completed in 108 (80%) subjects, showing type 'a' as the most common variant in 93(68.9%). The posterior part of the circle was completed in 30 (22.2%) subjects with type 'e' variant in 52(38.5%). CONCLUSIONS: There was a wide variability in the anatomy of the Circle of Willis in Pakistani adults asymptomatic for cerebrovascular disease.

3D TOF MR angiography to depict pituitary bright spot and to detect posterior pituitary lobe cyst: Original description at 3T MR imaging.

PURPOSE: There is no detailed description of the pituitary bright spot (PBS) at 3T in the literature. This study assesses detection of PBS on axial source images of 3D TOF sequence at 3T, and reports cysts in this location for the first time. METHODS: We retrospectively studied 250 consecutive patients who underwent brain 3T MRI with high resolution 3D TOF angiogram and thin axial T2-weighted sequences. On the axial source images of the 3F TOF, we assessed the presence, location and shape of the PBS. A cyst was diagnosed within the PBS in cases with central sharply defined low-TOF signal intensity surrounded by a rim of hyperintense signal. High T2 signal intensity corresponding precisely with the low T1 signal was also necessary for the diagnosis of such cysts. Evolution of these cysts was assessed on follow-up MRI. RESULTS: PBS was depicted in 83% of patients. Prevalence was significantly higher in women than in men (89% vs 70%, P<0.01). Patients with PBS were significantly younger than those without (mean age 54.1 years vs 59.4 years, P<0.05). A cyst within the PBS was depicted in six patients (2.9%). Mean size was 1.9 mm. These cysts were asymptomatic and remained stable during follow-up. CONCLUSIONS: Axial source images of 3D TOF angiogram can be used to assess the posterior pituitary lobe as the PBS was detected in 83% of our cohort. When cysts are seen within, they may be considered incidental findings that remained stable at follow-up.

Two Cases of Rare Basilar Hypoplasia.

In this article, we report two cases of basilar artery hypoplasia; the first case was a primitive trigeminal artery, and the second was an isolated basilar artery hypoplasia. Both patients had general neurologic disturbances, including periodic intention tremor of the left hand. Our data underscore the utility of complementary time of flight (TOF) magnetic resonance and multidetector computed tomography (MDCT) angiography as reliable first detection methods for steno-occlusive diseases and in cases of suspected congenital vascular anomalies.

A comparison between magnetic resonance angiography at 3 teslas (time-of-flight and contrast-enhanced) and flat-panel digital subtraction angiography in the assessment of embolized brain aneurysms

PURPOSE: To compare the time-of-flight and contrast-enhanced- magnetic resonance angiography techniques in a 3 Tesla magnetic resonance unit with digital subtraction angiography with the latest flat-panel technology and 3D reconstruction in the evaluation of embolized cerebral aneurysms. INTRODUCTION: Many embolized aneurysms are subject to a recurrence of intra-aneurismal filling. Traditionally, imaging surveillance of coiled aneurysms has consisted of repeated digital subtraction angiography. However, this method has a small but significant risk of neurological complications, and many authors have advocated the use of noninvasive imaging methods for the surveillance of embolized aneurysms. METHODS: Forty-three aneurysms in 30 patients were studied consecutively between November 2009 and May 2010. Two interventional neuroradiologists rated the time-of-flight-magnetic resonance angiography, the contrast-enhanced-magnetic resonance angiography, and finally the digital subtraction angiography, first independently and then in consensus. The status of aneurysm occlusion was assessed according to the Raymond scale, which indicates the level of recanalization according to degrees: Class 1: excluded aneurysm; Class 2: persistence of a residual neck; Class 3: persistence of a residual aneurysm. The agreement among the analyses was assessed by applying the Kappa statistic. RESULTS: Inter-observer agreement was excellent for both methods (K = 0.93; 95 percent CI: 0.84-1). Inter-technical agreement was almost perfect between time-of-flight-magnetic resonance angiography and digital subtraction angiography (K = 0.98; 95 percent CI: 0.93-1) and between time-of-flight-magnetic resonance angiography and contrast-enhanced-magnetic resonance angiography (K = 0.98; 95 percent CI: 0.93-1). Disagreement occurred in only one case (2.3 percent), which was classified as Class I by time-of-flight-magnetic resonance angiography and Class II by digital subtraction angiography. The agreement between contrast-enhanced-magnetic resonance angiography and digital subtraction angiography was perfect (K = 1; 95 percent CI: 1-1). In three patients, in-stent stenosis was identified by magnetic resonance angiography but not confirmed by digital subtraction angiography. CONCLUSION: Digital subtraction angiography and both 3T magnetic resonance angiography techniques have excellent reproducibility for the assessment of aneurysms embolized exclusively with coils. In those cases also treated with stent remodeling, digital subtraction angiography may still be necessary to confirm eventual parent artery stenosis, as identified by magnetic resonance angiography.