Super-early images of brain perfusion SPECT using 123 I-IMP for the assessment of hyperperfusion in stroke patients

Abstract

Objective

With the advancement of reperfusion therapy in stroke patients, assessment of perfusion status after therapy is gaining importance. Hyperperfusion tends to be underestimated by the conventional early imaging of ¹²³I-IMP brain perfusion SPECT. We evaluated the utility of super-early imaging as an adjunct to early imaging for the assessment of postischemic hyperperfusion in stroke patients.

Methods

Sixty-seven patients who underwent ¹²³I-IMP brain perfusion SPECT within 14 days after the onset of cerebral infarction were retrospectively analyzed. Super-early (4–10 min) and early (15–45 min) images were acquired using a dual-headed gamma camera. Postischemic hyperperfusion was visually assessed using the early images alone and then using both the super-early and early images, and the frequency of postischemic hyperperfusion and the confidence level of the judgement were evaluated. For quantitative evaluation of image contrast, the contrast ratios (the count ratios of the hyperperfused to normal areas) were calculated.

Results

The frequency of postischemic hyperperfusion was significantly higher using both the super-early and early images (28/67 patients) than using the early images alone (17/67 patients, p < 0.001). In 56 patients in whom judgement regarding the presence or absence of postischemic hyperperfusion was unchanged, the confidence level was increased in 8 patients using both image sets. The addition of the super-early SPECT images was judged to be useful and marginally useful in 14 and 15 patients, respectively. The contrast ratio was significantly higher on the super-early images (1.48 ± 0.25) than on the early images (1.26 ± 0.18, p < 0.001).

Conclusions

The addition of super-early imaging to the conventional early imaging aids assessment of postischemic hyperperfusion by ¹²³I-IMP brain perfusion SPECT and may contribute to management of stroke patients in the era of reperfusion therapy.