Assessment of extracranial–intracranial bypass patency with 64-slice multidetector computerized tomography angiography

High-resolution compressed sensing time-of-flight MR angiography outperforms CT angiography for evaluating patients with Moyamoya disease after surgical revascularization

Background

To evaluate the utility of high-resolution compressed sensing time-of-fight MR angiography (CS TOF-MRA) for assessing patients with moyamoya disease (MMD) after surgical revascularization, by comparison with computer tomography angiography (CTA).

Methods

Twenty patients with MMD after surgical revascularizations who underwent CS TOF-MRA and CTA were collected. The scan time of CS TOF-MRA was 5 min and 4 s, with a reconstructed resolution of 0.4 × 0.4 × 0.4 mm³. Visualization of superficial temporal artery and middle cerebral artery (STA–MCA) bypass, neovascularization into the brain pial surface and Moyamoya vessels (MMVs) were independently ranked by two neuroradiologists on CS TOF-MRA and CTA, respectively. The patency of anastomosis was assessed as patent or occluded, using digital subtraction angiography and expert’s consensus as ground truth. Interobserver agreement was calculated using the weighted kappa statistic. Wilcoxon signed-rank or Chi-square test was performed to investigate diagnostic difference between CS TOF-MRA and CTA.

Results

Twenty-two hemispheres from 20 patients were analyzed. The inter-reader agreement for evaluating STA–MCA bypass, neovascularization and anastomosis patency was good to excellent (κ_{CS TOF-MRA}, 0.738–1.000; κ_CTA, 0.743–0.909). The STA–MCA bypass and MMVs were better visualized on CS TOF-MRA than CTA (both P < 0.05). CS TOF-MRA had a higher sensitivity than CTA (94.7% vs. 73.7%) for visualizing anastomoses. Neovascularization was better observed in 13 (59.1%) sides on CS TOF-MRA, in comparison to 7 (31.8%) sides on CTA images (P = 0.005).

Conclusion

High-resolution CS TOF-MRA outperforms CTA for visualization of STA–MCA bypass, neovascularization and MMVs within a clinically reasonable time in MMD patients after revascularization.

Coloring Technique of Magnetic Resonance Angiography for Superficial Temporal Artery to Middle Cerebral Artery Bypass Surgery

OBJECTIVE

Superficial temporal artery (STA)-to-middle cerebral artery (MCA) bypass is an established surgical technique for achieving revascularization. It is important to select the proper recipient artery of the MCA. Three-dimensional computed tomographic angiography (3D-CTA) and conventional angiography are useful in the selection process but need contrast agents. The authors have designed a coloring MRA technique that needs no agents to visualize the recipient artery. Retrospective evaluation of the efficacy and limitation for selection of the recipient artery and decision of the place and size of the craniotomy were carried out.

METHODS

The authors performed the coloring MRA before operation since January 2013. Ninety-two patients underwent STA-MCA bypass for atherosclerotic stenosis or occlusion of internal carotid artery (ICA), MCA with reference to the coloring MRA. To evaluate the efficacy of coloring MRA, the control group consisted of 75 patients who underwent STA-MCA bypass between January 2012 to November 2013 with reference to 3D-CTA. The size of craniotomy was retrospectively calculated and compared.

RESULTS

Neither additional craniotomy nor wrong selection of the recipient artery was done in either group. There was no significant difference in size between the 2 groups in both single and double bypass.

CONCLUSIONS

The coloring MRA technique was not inferior to 3D-CTA with respect to the size of craniotomy. This novel technique was found to be very helpful not only for the virtual identification of the proper recipient artery but also for preoperative simulation such as decisions about length of donor artery, location, and size of craniotomy.

Cerebrovascular Imaging: Which Test is Best?

Optimal diagnosis and characterization of cerebrovascular disease requires selection of the appropriate imaging exam for each clinical situation. In this review, we focus on intracranial arterial disease and discuss the techniques in current clinical use for imaging the blood vessel lumen and blood vessel wall, and for mapping cerebral hemodynamic impairment at the tissue level. We then discuss specific strategies for imaging intracranial aneurysms, arteriovenous malformations, dural arterial venous fistulas, and arterial steno-occlusive disease.

Imaging after direct and indirect extracranial-intracranial bypass surgery

OBJECTIVE

The purpose of this article is to describe the imaging features of different types of surgical cerebral revascularization techniques.

CONCLUSION

Surgical cerebral revascularization involves direct and indirect techniques. Direct revascularization entails anastomosing a branch of the external carotid artery to a cerebral artery. Indirect revascularization involves delivering an extracranial vascular supply in proximity to the surface of the brain. The results of these techniques have distinctive imaging features.

Indocyanine green videoangiography for confirmation of bypass graft patency

OBJECTIVE

The aim of the study is to determine the efficacy of indocyanine green (ICG) videoangiography for confirmation of vascular anastomosis patency in both extracranial-intracranial and intracranial-intracranial bypasses.

METHODS

Intraoperative ICG videoangiography was used as a surgical adjunct for 56 bypasses in 47 patients to assay the patency of intracranial vascular anastomosis. These patients underwent a bypass for cerebral ischemia in 31 instances and as an adjunct to intracranial aneurysm surgery in 25. After completion of the bypass, ICG was administered to assess the patency of the graft. The findings on ICG videoangiography were then compared to intraoperative and/or postoperative imaging.

RESULTS

ICG provided an excellent visualization of all cerebral arteries and grafts at the time of surgery. Four grafts were determined to be suboptimal and were revised at the time of surgery. Findings on ICG videoangiography correlated with intraoperative and/or postoperative imaging.

CONCLUSION

ICG videoangiography is rapid, effective, and reliable in determining the intraoperative patency of bypass grafts. It provides intraoperative information allowing revision to reduce the incidence of technical errors that may lead to early graft thrombosis.