[^99mTc]3PRGD₂ for integrin receptor imaging of esophageal cancer: a comparative study with [¹⁸F]FDG PET/CT

Objectives

This study was designed to investigate the efficacy of ^99mtechnetium-three polyethylene glycol spacers-arginine–glycine–aspartic acid ([^99mTc]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 [^99mTc]3PRGD₂. 2-Deoxy-2-[¹⁸F] fluoro-D-glucose ([¹⁸F]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 α_vβ₃ was analyzed through immunohistochemistry.

Results

The T/B, SUVmax and expression of integrin α_vβ₃ 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 α_vβ₃ was correlated with [^99mTc]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 [¹⁸F]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 [¹⁸F] 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 [^99mTc]3PRGD₂ imaging is valuable for the diagnosis and staging of esophageal cancer. It may be less sensitive than [¹⁸F]FDG imaging for detecting metastatic lesions in small lymph nodes. The T/B value was correlated with the expression of integrin α_vβ₃. NIH ClinicalTrials.gov:

NCT 02744729.