Angiogenesis imaging of brain tumor and lung cancer: A SPECT study to evaluate [^99mTc]IDA-D-[c(RGDfK)]₂

Objectives Integrin α_vβ₃ has been proposed as a potential imaging target for radiolabeled RGD peptides and a molecular marker for tumor-specific angiogenesis. We evaluated the ability of [^99mTc]IDA-D-[c(RGDfK)]₂, a newly developed SPECT radioligand for the integrin α_vβ₃ imaging, for measuring angiogenesis in the brain tumor and lung cancer. Additionally, a correlation between [^99mTc]IDA-D-[c(RGDfK)]₂ and FDG uptake values was assessed to evaluate whether the both radioligands provide similar information implicated in tumor growth.

Methods Total 13 patients (brain tumor, n = 8; lung cancer, n = 5) were examined consecutively with SPECT using [^99mTc]IDA-D-[c(RGDfK)]₂ and FDG PET. Angiogenesis and [^99mTc]IDA-D-[c(RGDfK)]₂ uptake was measured as ipsilateral-to-contralateral uptake ratio (ICR) using [^99mTc]IDA-D-[c(RGDfK)]₂ SPECT images. FDG uptake was measured as SUV using FDG PET images.

Results Angiogenesis was visualized with varied uptake of [^99mTc]IDA-D-[c(RGDfK)]₂ in SPECT images. In brain tumor angiogenesis were highly contrasted with ICR of 7.7 ± 1.5. Whereas in the lung cancer the ratio was relatively low (ICR = 2.3 ± 0.4). In addition, no significant correlation was found between ICR of [^99mTc]IDA-D-[c(RGDfK)]₂ SPECT and SUV of FDG PET both in brain tumor (r = 0.519, P = 0.233) and lung cancer (r = 0.735, P = 0.157).

Conclusions [^99mTc]IDA-D-[c(RGDfK)]₂ elucidated tumor angiogenesis with moderate to high contrasts in the brain tumor and lung cancer. Data indicate that [^99mTc]IDA-D-[c(RGDfK)]₂ and FDG uptake values may not provide complementary information about tumor growth. Data demonstrated that [^99mTc]IDA-D-[c(RGDfK)]₂ is a promising radioligand for in vivo angiogenesis imaging.