Normal physiological distribution and tumor localization of 64CuCl2 in different human malignancies along with semiquantitative scoring: a comparative evaluation with 18Fluorodeoxyglucose (18FDG) PET-CT

Abstract

Objective This study aimed to explore 64-Copper-Chloride (64CuCl2) PET-CT in various malignancies and demonstrate a head-to-head comparison of uptake on 64CuCl2 PET/computed tomography (CT) and 18fluorodeoxyglucose (18FDG)-PET/CT scans for different malignancies, with an emphasis on 18FDG nonavid malignancies. Methods Fifty-three patients diagnosed with various biopsy-proven malignancies (except prostate cancer) were recruited in this prospective study. All the patients underwent both 64CuCl2 PET/CT and 18FDG-PET/CT. 64CuCl2 PET/CT was acquired at 1, 3 and 24 h time points. We studied the physiological biodistribution of 64CuCl2 in the various organs, corroborated the uptake of 64CuCl2 with various types of malignancies and comparison of their uptake with 18FDG-PET/CT and their correlation with each other in various lesions. Results The biodistribution study showed that the liver concentrated 64CuCl2 the most out of all the organs, followed by the pancreas and large intestine. Liver and intestinal activity increased subsequently with delayed imaging, and the washout of 64CuCl2 was noted in the pancreas in delayed images and followed a hepatobiliary excretion of tracer over a period of time. In lesion-wise analysis, it was noted that the primary neuroendocrine tumor, melanoma and renal/urothelial malignancy group showed more uptake of 64CuCl2, than that in metastasis and vice-versa was noted in lung and soft tissue malignancies. Comparing it with 18FDG, it was seen that FDG showed more uptake in lesions and showed no significant correlation (Kappa value: 0.089) with the uptake of 64CuCl2 in the lesion-wise comparison. Conclusion 64CuCl2 PET/CT did not show any added advantage over 18FDG-PET/CT in the evaluation of the studied malignancies, both primary and their metastasis. Biodistribution studies showed the liver as the organ with maximum uptake, which implies it may hinder the detection of abdominal or hepatic involvement of the disease.