[ 99m Tc]3PRGD 2 for integrin receptor imaging of esophageal cancer: a comparative study with [ 18 F]FDG PET/CT.

OBJECTIVES: This study was designed to investigate the efficacy of 99m technetium-three polyethylene glycol spacers-arginine-glycine-aspartic acid ([99m Tc]3PRGD2 ) in the evaluation of patients with esophageal cancer.

METHODS: Twenty-nine patients with a suspected esophageal lesion and for whom definite pathological diagnosis was finally obtained were recruited. Whole-body planar scanning and chest single-photon-emission computed tomography/computed tomography (SPECT/CT) were performed at 30 and 40 min, respectively, after intravenous injection of 11.1 MBq/kg of [99m Tc]3PRGD2 . 2-Deoxy-2-[18 F] fluoro-D-glucose ([18 F]FDG) positron-emission tomography/computed tomography (PET/CT) was performed in 1 week. The tumor-to-background ratio (T/B) and the maximum standard uptake value (SUVmax) were calculated for semi-quantitative and quantitative analyses. Integrin αv β3 was analyzed through immunohistochemistry.

RESULTS: The T/B, SUVmax and expression of integrin αv β3 in malignant lesions were higher than those in benign lesions (t = 3.691, P = 0.001; t = 8.271, P = 0.000; t = 3.632, P = 0.001, respectively). There was a significant correlation between T/B and SUVmax in esophageal lesions (r = 0.660, P = 0.000). The expression of integrin αv β3 was correlated with [99m Tc]3PRGD2 uptake (r = 0.782, P = 0.000). In visual analysis, the sensitivity and accuracy of the whole-body planar RGD scan were lower than those of the chest SPECT/CT RGD scan and the [18 F]FDG PET/CT scan (x2  = 6.769, P = 0.022). The sensitivity, specificity and accuracy of the chest SPECT/CT RGD scan were similar to those of the [18 F] FDG PET/CT scan. In semi-quantitative analysis, the sensitivity, specificity and accuracy of chest SPECT/CT RGD from the receiver operating characteristic (ROC) analysis were 87%, 100% and 94%, respectively [cutoff = 3.1 of T/B, area under the curve (AUC) = 0.957]. Thirteen patients (30 lymph nodes) and 16 patients (105 lymph nodes) were suspected to have lymph node metastases based on the RGD and FDG scans, respectively.

CONCLUSION: This prospective study demonstrated that [99m Tc]3PRGD2 imaging is valuable for the diagnosis and staging of esophageal cancer. It may be less sensitive than [18 F]FDG imaging for detecting metastatic lesions in small lymph nodes. The T/B value was correlated with the expression of integrin αv β3 . NIH CLINICALTRIALS.GOV: NCT 02744729.