The assessment of STA-MCA anastomosis by the method of intracarotid injection of 99mTc-labeled human albumin microsphere

Since Yasargil and Donaghy performed the first human extracranial intracranial bypass procedure in 1967 by anastomosing branches of the superficial temporal artery to cortical branches of the middle cerebral artery, this procedure (STA-MCA anastomosis) has been widely available and applied to the therapy of the ischemic cerebrovascular disease. In this study, the method of intracarotid injection of 99mTc-labeled human albumin microsphere (HAM) was newly employed for the assessment of the regional blood perfusion through the STA-MCA anastomosis in 15 cases treated by the bypass surgery. Clinical manifestations were transient focal ischemic attacks (TIAs) in 7 cases, reversible ischemic neurologic deficits (RIND) in 2, minor stroke in 5 and completed stroke in 1. Preoperative angiographic findings were unilateral internal carotid artery (ICA) occlusion in 11 cases, bilateral ICA occlusion in 2, MCA occlusion in 1 and MCA stenosis in 1. In these 15 cases, 17 anastomoses were performed. Human Albumin Microsphere Kit (TCK-5-s) was used for the assessment of regional blood perfusion in these cases. Five mCi of 99mTc-labeled HAM (approximately 80, 000 particles) were injected into the common carotid artery on the bypassed side using a glass syringe connected with 22 gauge needle in the case with ICA occlusion and into the external carotid artery by means of selective catheterization in the case with MCA occlusion or MCA stenosis. The brain scintigrams (HAM scintigrams) were obtained from anterior, Townes, vertex, posterior and the lateral view on the bypassed side immediately after the injection of the tracer. The HAM scintigrams revealed the intracranial perfusion area perfused by the anastomotic vessel as well as the area perfused by external carotid artery i.e., face, nose and scalp. For example, the anterior view clearly showed the perfused area corresponding to a part of the hemisphere and to a scalp, face and nose (Fig 1A). The lateral view also demonstrated the intracranial perfusion area through the anastomosis in the posterior part of MCA system and extracranial perfusion area (Fig. 1B). Postoperative angiography revealed intracranial vascular filling of posterior part of MCA in this case. From multiple view, thus the intracranial perfused area through anastomosis was easily discriminated from the perfused area of external carotid artery in each case. The scintigraphic results were well compatible with the findings in postoperative angiography (Table 1)