Advantages of 99m Tc-3PRGD 2 SPECT over CT in the preoperative assessment of lymph node metastasis in patients with esophageal cancer

Background Our study was designed to compare the diagnostic efficacies of integrated 99m Tc-HYNIC-PEG4-E[PEG4-c(RGDfK)]2 ( 99m Tc-3PRGD 2 ) single-photon emission computed tomography (SPECT) images and computed tomography (CT) images in lymph node metastasis in the patients with esophageal cancer. Methods From September 2015 and May 2018, 32 patients with histologically proven primary esophageal carcinoma underwent both 99m Tc-3PRGD 2 SPECT and CT scans followed by esophagectomy with lymph node dissection. The results of reviewing 99m Tc-3PRGD 2 SPECT and CT images for the lymph node metastasis were compared in relation with pathologic findings. Results During surgery, a total of 168 lymph nodes were dissected in 32 patients, of which 42 node groups in 18 patients were malignant on histologic examination. Preoperative nodal staging was compared with postoperative histopathological staging, The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 99m Tc-3PRGD 2 SPECT for lymph nodes were 80.95%, 86.51%, 85.12%, 66.67%, and 93.16% on per-node basis, respectively; compared with 59.52%, 73.02%, 69.64%, 42.37%, and 84.40% for CT ( p = 0.034, 0.008, 0.005, 0.011, and 0.038, respectively). 70.59% (12/17) false-negative interpretations and 50% (17/34) false-positive interpretations on CT were corrected by 99m Tc-3PRGD 2 SPECT. 37.5% false-negative interpretations on 99m Tc-3PRGD 2 SPECT were corrected by CT. 11.90% (5/42) positive lymph nodes and 13.49% (17/126) negative nodes at pathology were incorrectly diagnosed both by 99m Tc-3PRGD 2 SPECT and CT. The accuracy of 99m Tc-3PRGD 2 SPECT (87.50%, 28/32) was significantly higher than that of CT (62.50, 20/32; p = 0.022) on per-patient basis. 99m Tc-3PRGD 2 SPECT showed significantly higher sensitivity and accuracy in the neck and upper thoracic regions than CT. For nodal staging, 99m Tc-3PRGD 2 SPECT was correct in 78.12% (25/32) of the patients, whereas CT was correct in 53.12% (17/32), p = 0.037. Conclusion 99m Tc-3PRGD 2 SPECT is more accurate than CT for preoperative assessment of lymph node metastasis in esophageal cancer and may be helpful in determining the therapeutic plan.