A Comparative Study Of ^99mTc-3PRGD₂ SPECT And Thin-Slice CT In The Preoperative Assessment Of Lymph Node Metastasis In Patients With Esophageal Cancer

Objective:Our study was designed to compare the diagnostic value of integrated^99mTc-HYNIC-PEG₄-E[PEG₄-c（RGDfK）]₂(^99mTc-3PRGD₂)single photon emission computed tomography（SPECT）images and thin-slice computed tomography（CT）images in lymph node metastasis of patients with esophageal cancer.Material and methods:From September 2015 to May 2018,32 patients（27 males and 5 females;age range:37-81 years）who were confirmed to be primary esophageal cancer without distant metastases and underwent esophagectomy and lymph node dissection were included in this study.None of the patients had received surgery,radiotherapy or chemotherapy.Thin-slice CT imaging and ^99mTc-3PRGD₂SPECT imaging were performed within one week before surgery.^99mTc-3PRGD₂SPECT Imaging:scanning from the neck to the upper abdomen was performed 1 hour after injection,injection dose was 11.1MBq/kg.Visual analysis was used for imaging results,lymph nodes with obvious radioactivity concentration（uptake higher than the mediastinum）at two or more consecutive levels were considered positive.Thin-layer CT imaging:64-row spiral CT scanner was used.From the neck to the kidney,scanned along the head and foot direction.Positive criteria were the shortest diameter of regional lymph nodes more than 1.0 cm.Pathological diagnosis served as gold standard.The comparison of the diagnostic value between the two imaging methods were based on per lymph node analysis,per patient analysis,different lymph node regions and lymph node staging.X²test was used to compared the diagnostic index.P<0.05 was considered statistically significant.Results:A total of 168 lymph nodes（51 cervical nodes,43 superior thoracic nodes,27middle thoracic nodes,14 inferior thoracic nodes and 33 abdominal nodes）were dissected.Among them,42 metastatic lymph nodes in 18 patients were found on histologic examination.Thin-slice CT imaging found 117 lymph nodes,of which 25were positive and 92 were negative.^99mTc-3PRGD₂SPECT imaging found 143 lymph nodes,of which 34 were positive and 109 were negative.On per lymph node analysis,^99mTc-3PRGD₂SPECT imaging in the diagnosis of metastatic lymph nodes was significantly higher than thin-slice CT imaging:Sensitivity（80.95%vs.59.52%,P<0.05）,specificity（86.51%vs.73.02%,P<0.05）,accuracy（85.12%vs.69.64%,P<0.05）,positive predictive value（66.67%vs.42.37%,P<0.05）and negative predictive value（93.16%vs.84.40%,P<0.05）.On per patient analysis,^99mTc-3PRGD₂SPECT imaging had a higher diagnostic accuracy（87.50%vs.62.50%,P<0.05）than thin-slice CT imaging.On region-based analysis of lymph nodes,^99mTc-3PRGD₂SPECT in the diagnosis of lymph nodes in the neck and upper thoracic region were higher than those of thin-slice CT:Sensitivity（92.86%vs.57.14%,P<0.05）and accuracy（90.20%vs.72.55%,P<0.05）.In lymph node staging,the diagnostic accuracy of ^99mTc-3PRGD₂SPECT imaging was higher than that of thin-slice CT imaging（78.12%vs.53.12%,P<0.05）.Conclusion:^99mTc-3PRGD₂SPECT imaging has higher sensitivity,specificity and accuracy in the preoperative assessment of lymph node metastasis of esophageal carcinoma than thin-slice CT imaging,especially in the cervical and upper thoracic region.