The new MRI modalities "BPAS and VISTA" for the diagnosis of VA dissection

Recently VA dissection has drawn attention as a relatively common cause of stroke because of the introduction of MRI as a diagnostic technique. Basiparallel anatomic scanning (BPAS) was designed to visualize the surface appearance of the vertebrobasilar artery within the cistern. Volumetric isotropic TSE acquisition (VISTA) is a sort of black blood imaging method to evaluate the arterial wall and lumen. In this study, we aimed to evaluate the efficacy of the new MRI modalities "BPAS and VISTA," and to present a retrospective analysis of our experience with the diagnosis.

Between1995 and 2010, we experienced 24 cases of VA dissection at our institution. In our cases, we could obtain images of 15 in BPAS and VISTA in addition to MRA. The mean age of the 15 patients (12 male and 3 female) was 51 years old (range 18-80). Ten of fifteen patients presented with ischemia, and 5/15 with only headache. There were no cases of SAH. In BPAS, we evaluated dilatation of the external diameter of the affected artery. We compared the findings in BPAS with MRA to evaluate the discrepancy. In VISTA, we evaluated its capability to distinguish intramural hematoma.

Thirteen of fifteen patients presented with dilatation of the external diameter on BPAS. By comparing the findings in BPAS with MRA, we found a discrepancy in 8/15 cases (53%). We could detect intramural hematoma by using VISTA in 9/15 cases (60%). Thirteen of fifteen patients received follow-up MRI. Temporal change of the arterial shape was confirmed in 7/13 cases (53.8%).

Dilatation of the external diameter was shown highly frequently in VA dissections. In addition, a discrepancy between BPAS and MRA as well as the intramural hematoma on VISTA was found comparatively frequently. BPAS and VISTA are minimally invasive and useful methods as screening tests.