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The relationship between hyperperfusion and temporary clipping was evaluated to determine the safe limit for the duration of temporary clipping in aneurysm surgery. Twenty-one patients surgically treated for a ruptured aneurysm were examined using xenon-enhanced computed tomography on postoperative days 4 to 13. Eight of the 16 patients undergoing temporary clipping had focal hyper perfusion; whereas the five patients without temporary clipping had no hyperperfusion.Mean total temporary clipping time in patients with hyperperfusion was significantly longer than that in pa tients without (31.9 vs. 13.9 minutes, p = 0.0157) and mean maximum single temporary clipping time in patients with hyperperfusion was also significantly longer than in patients without (18.4 vs. 8.6 minutes, p = 0.0313). Moreover, cerebral infarction was related to hyperperfusion (p = 0.0027). These results support the hypothesis that temporary clipping during aneurysm surgery causes post operative hyperperfusion and cerebral infarction. Temporary clipping may be harmful when per formed for more than 20 minutes of total duration, since postoperative hyperperfusion was seen under this condition.

The purpose of this study was to evaluate the usefulness of contrast-enhanced 3D MR angiography (CE-MRA) with an automated bolus-detection algorithm (SmartPrep technique) and the specialized phased-array coils for the patients suspected cerebrovascular disease. Forty-three patients with brain attack were examined with CE-MRA. A tracker volume of SmartPrep technique was placed along the ascending aorta in the coronal image. After the bolus injection of gadolinium, an increase in signal that corresponded to the arrival of gadolinium was used to trigger centric re-ordered spoiled gradient echo arterial selective MRA with imaging time of 20-40 sec. We were able to achieve a 100% successful triggering rate of SmartPrep technique and selectively arterial-phase carotid and vertebral arteries with almost no venous contamination could be delineated. These techniques enabled high resolution imaging of entire craniocervical arteries from aortic arch to the circle of Willis. This CE-MRA was useful to evaluate both occlusion of arteries and the collateral pathways and to measure stenosis and residual flow of dissection accurately. CE-MRA was a reliable less-invasive alternative to investigate the patients of cerebrovascular disease.

Cerebral vasodilatory capacity was evaluated by acetazolamide-activated N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) single photon emission computed tomography (SPECT) in 42 patients with subarachnoid haemorrhage (SAH). A low perfusion area was present in the corresponding region of haematoma seen on the CT and continued to be noted throughout the time courses. Deteriorated acetazolamide reactivity affected by surgical intervention was seen in 100% of the patients who underwent aneurysm repair in the 1st postoperative week, 92% in the second week, 73% in the third week, and 47% in the fourth week. Three patients with acute diffuse brain swelling seen on CT showed intracranial non-filling of 123I-IMP on SPECTs performed on Day 6, and all three died by Day 10. Some low perfusion areas, due to probable vasospasm, were present in 77% of Hunt and Hess grades I and II patients and in 100% of grades III, IV, and V patients throughout their time courses. Overall, low perfusion areas, due to probable vasospasm, were seen in 10 patients (31%) of 32 who underwent SPECT between Day 4 and 8,23 (77%) of 30 between Day 9 and 14, 21 (72%) of 29 between Day 15 and 21, and 11 (48%) of 23 between Day 22 and 28. The results suggest acetazolamide-activated 123I-IMP study is of value in evaluating changes in vasodilatory capacity in SAH patients in the acute and subacute stages.

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