Iodine-123-Iomazenil Single-Photon Emission Computed Tomography Revealed Recovery of Neuronal Viability in Association With Improvement of Cognitive Dysfunction After Revascularization in Moyamoya Disease

BACKGROUND AND OBJECTIVES: Recent studies indicate that 123 I-iomazenil ( 123 I-IMZ) single-photon emission computed tomography (SPECT) can demonstrate neuronal viability. Although cognitive dysfunction has been recognized as an important issue in adult patients with moyamoya disease (MMD), no standard neuroradiological methods to define such conditions have been established. We examined the relationship between cognitive function and 123 I-IMZ SPECT before and after revascularization in patients with MMD. METHODS: The study participants were 16 adult patients with MMD whose cerebrovascular reactivities were decreased only on the surgical sides of combined revascularization. Cognitive function was examined using the Mini-Mental State Examination (MMSE; cutoff: 27) and the Frontal Assessment Battery (FAB; cutoff: 16) before and at 3 to 6 months after surgery. 123 I-iodoamphetamine ( 123 I-IMP) SPECT with acetazolamide challenge and 123 I-IMZ SPECT were performed concurrently while evaluating cognitive function. The radioreactivities of 123 I-IMZ SPECT in regions with decreased cerebrovascular reactivities on 123 I-IMP SPECT were investigated using affected-to-contralateral side asymmetry ratio (IMZ-ACR). RESULTS: Twelve patients showed normal cognitive function (MMSE: 29.8 ± 0.4, FAB: 18 ± 0) before surgery. No evident laterality of 123 I-IMZ uptake was seen (IMZ-ACR: 0.98 ± 0.04). Neither cognitive function nor 123 I-IMZ SPECT worsened after surgery (MMSE: 29.8 ± 0.3, FAB: 18 ± 0, IMZ-ACR: 1.00 ± 0.04). By contrast, 4 patients presented cognitive dysfunction (MMSE: 24.3 ± 3.9, FAB: 14.8 ± 2.7) before revascularization. Preoperative imaging of these patients showed decreased 123 I-IMZ uptake, and their IMZ-ACRs (0.83 ± 0.08) were significantly lower than those of the normal group. After revascularization, cognitive functions and 123 I-IMZ uptake tended to ameliorate (MMSE: 27.5 ± 1.7, FAB: 16.3 ± 2.2, IMZ-ACR: 0.94 ± 0.09). CONCLUSION: Preoperative cognitive function was associated with 123 I-IMZ uptake in adult patients with MMD. After revascularization, cognitive function could be recovered in the viable areas of the brain, which is consistent with 123 I-IMZ SPECT findings.