Residual flow after cerebral aneurysm coil occlusion: diagnostic accuracy of MR angiography.

BACKGROUND AND PURPOSE: The purpose of this study was to estimate the performance measures of MR angiography (MRA) in the diagnosis of aneurysm residual flow after coil occlusion. METHODS: Patients having at least 1 cerebral aneurysm treated with coil occlusion were prospectively and consecutively enrolled. Time of flight and contrast-enhanced MRA were performed the same day of the DSA follow-up. The degree of aneurysm occlusion and dimensions of the residual flow were evaluated by independent readers at MRA and digital subtraction angiogram. MRA performance measures were estimated in a cross-sectional analysis and repeated in subgroups of aneurysm sizes and locations. MRA predictive values for recurrence were also estimated using a longitudinal design. RESULTS: We obtained 167 aneurysm evaluations for each imaging modality. Class 3 residual flow was seen on digital subtraction angiogram follow-up in 27%. The sensitivity and specificity of MRA was 88% (95% CI, 80-94) and 79% (95% CI, 67-88), respectively. The positive predictive value for a Class 3 recurrence was 67% (95% CI, 51-80) and the negative predictive value was 93% (95% CI, 86-97). Time-of-flight MRA underestimated the length of the residual flow (P=0.039), whereas contrast-enhanced MRA overestimated its width (P<0.0001). MRA sensitivity for a Class 3 residual flow was lower for aneurysms <6 mm (P=0.01). CONCLUSIONS: MRA has sufficient accuracy for screening of aneurysm residual flow after coil occlusion. Due to its lower negative predictive value, recurrent aneurysms should be confirmed with digital subtraction angiogram before planning a retreatment. Routine use of MRA to follow small aneurysms should wait better estimation of its performance in this particular subgroup.

Selective 4 vessels angiography in brain death: a retrospective study.

BACKGROUND: In Canada, ancillary tests, such as selective four vessels angiography (S4VA), are sometimes necessary for brain death (BD) diagnosis when the clinical exam cannot be completed or confounding factors are present. Recent Canadian guidelines assert that brain death is supported by the absence of arterial blood flow at the surface of the brain and that venous return should not be considered. However, neuropathologic and angiographic studies have suggested that arteries might still be patent in BD patients. Current clinical practices in BD diagnosis following S4VA need to be better understood. METHODS: We conducted a retrospective study of all S4VA performed for the determination of BD in a level 1 NeuroTrauma centre from 2003 to 2007. The objective of the study was to describe the prevalence of intracranial arterial, capillary (parenchymogram) and venous opacification in our study population. All tests were reviewed independently by two neuroradiologists. Disagreements were resolved by consensus. RESULTS: Thirty two patients were declared BD following S4VA during the study period. Nine of these patients (28%) presented some proximal opacification of intracranial arteries (95% CI 15-45%). As opposed, none had a cerebral capillary and deep venous drainage opacification (95% CI 0-10%). CONCLUSION: The absence of cerebral deep venous drainage or parenchymogram might represent a better objective marker of cerebral circulatory arrest for brain death diagnosis when the use of S4VA is required. These findings open the path for further research in enhancing our interpretation of angiographic studies for brain death diagnosis.