Iodine-123-iomazenil SPECT Revealed Recovery of Neuronal Viability in Association with Improvement of Cognitive Dysfunction after Revascularization in Moyamoya Disease

Introduction: Recent studies indicate that ¹²³I-iomazenil (¹²³I-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. This study aimed to examine the relationship between cognitive function and ¹²³I-IMZ SPECT before and after revascularization in adult patients with MMD with unilateral hemodynamic failure.Recent studies indicate that ¹²³I-iomazenil (¹²³I-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. This study aimed to examine the relationship between cognitive function and ¹²³I-IMZ SPECT before and after revascularization in adult patients with MMD with unilateral hemodynamic failure.

Methods: The study participants were adult patients with MMD without large ischemic or hemorrhagic lesions whose cerebrovascular reactivities (CVRs) were decreased only on the surgical sides of combined revascularization (superficial temporal artery–middle cerebral artery anastomosis combined with encephalo-duro-arterio-synangiosis). Cognitive function was examined using the Mini-Mental State Examination (MMSE; cutoff: 27) and the Frontal Assessment Battery (FAB; cutoff: 16) before and at 3–6 months after surgery. ¹²³I-iodoamphetamine (¹²³I-IMP) SPECT with acetazolamide challenge and ¹²³I-IMZ SPECT were performed concurrently while evaluating cognitive function. The radioreactivities of ¹²³I-IMZ SPECT in regions with decreased CVRs on ¹²³I-IMP SPECT were investigated using affected-to-contralateral side asymmetry ratio (IMZ-ACR).

Results: In total, 16 patients (ischemic onset: 10, hemorrhagic onset: 2, asymptomatic: 4) were included in the study, 12 of whom showed normal cognitive function (MMSE: 29.8 ± 0.4, FAB: 18 ± 0) before surgery. No evident laterality of ¹²³I-IMZ uptake was seen (IMZ-ACR: 0.98 ± 0.04). Neither cognitive function nor ¹²³I-IMZ SPECT worsened after surgery (MMSE: 29.8 ± 0.3, FAB: 18 ± 0, IMZ-ACR: 1.00 ± 0.04). By contrast, four patients presented cognitive dysfunction (MMSE: 24.3 ± 3.9, FAB: 14.8 ± 2.7) before revascularization. Preoperative imaging of these patients showed decreased ¹²³I-IMZ uptake, and their IMZ-ACRs (0.83 ± 0.08) were significantly lower than those of the normal group (P<0.01). After revascularization, cognitive functions and ¹²³I-IMZ uptake tended to ameliorate (MMSE: 27.5 ± 1.7, FAB: 16.3 ± 2.2, IMZ-ACR: 0.94 ± 0.09).

Conclusions: Preoperative cognitive function was associated with ¹²³I-IMZ uptake in adult patients with MMD. After revascularization surgery, cognitive function could be recovered in the viable areas of the brain, which is consistent with ¹²³I-IMZ SPECT findings.