[Single-photon emission-computed tomography in the diagnosis of cerebrovascular diseases]

SPECT-HM-PAO allows to detect the regional cerebral blood flow and total diminution of the brain perfusion still before morphological substrate evolution in CT scan, without invasive technologies. SEARCH GOAL: The authors have analyzed data obtained by SPECT-99mTc HM-PAO in the group of 46 patients suffering from cerebrovascular disorders and they have compared them with results aimed by CT scans. Both, the SPECT-99mTc HM-PAO and CT scan were performed within 48 hours or later after the onset of the stroke; some of CT scans were repeatedly performed.

They discovered 40 positive and 6 negative SPECT-HM-PAO findings, 26 positive and 20 negative CT scans. SPECT investigation more frequently discovers circulatory failures in the clinically altered hemisphere than the CT scan does in a substrate; SPECT discloses hypoperfusion of the clinically unaltered hemisphere if silent hypoperfusion is present. The ipsilateral foci of CT substrates were significantly less frequently observed (p < 0.001) than some ipsilateral regional hypoperfusions. Not only the number, but also size and extent of hypoperfusional foci searched by SPECT are significantly higher and wider than the numbers and dimensions of substrates observed by CT (p < 0.001).

CT scan diagnostic possibilities are restricted by the time factor (CT examinations performed within 48 hours since the onset of the stroke are significantly less frequently positive than those performed later-p < 0.001). SPECT examination has not such a limiting time factor (p > 0.05). MEANING: Hence SPECT-HM-PAO renders early, long lasting and wide information on the restriction of the overall and regional perfusion, independently of the fact as to whether the reduction of cerebral perfusion is, or is not going to result in ischemic necrosis and/or ischemic sclerosis. SPECT renders correlation of the perfusion disorder earlier, wider in space, and more frequently than the CT scan, and therefore it is a prerequisite to the disclosure of the mentioned silent focal blood flow reductions. (Graph 12, Fig. 3, Ref. 4.)