Diagnosis of ischemic cerebrovascular diseases with 99mTc-HMPAO brain SPECT using upright stress test

Purpose: To evaluate the value of upright brain SPECT stress test, the authors performed 99mTc-HMPAO brain SPECT in association with measurement of blood pressure in both upright and supine positions. Methods: The authors studied 5 patients with unilateral stenosis occlusion of the internal carotid (Group A), 8 patients with orthostatic hypotension (group B) and 7 normal controls. 370 MBq 99mTc-HMPAO was injected immediately after uprighting from a supine position. then the first SPECT scan were performed. After the first SPECT, another 555 MBq of 99mTc-HMPAO were administered while the patients remained on original supine position. Results: Semiquantitive analysis showed that the asymmetric ratios between upright and supine positions in group A changed significantly. In group B, showed postural cerebral hypoperfusion in the bilateral frontal areas, the mean count ratio of the frontal to cerebellar area between the upright and supine positions also significantly changed. In the normal group, there were no significantly changes during the upright test. Conclusions: The upright stress test is useful for detecting not only silent cerebral hypoperfusion, but also orthostatic hypoperfusion