Abstract
Background: The usefulness of preoperative lymph node metastasis diagnosis by 18F fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in colorectal cancer management has been reported, but inadequate diagnostic accuracy precludes routine preoperative application. Therefore, the purpose of this study was to examine the factors influencing the diagnostic accuracy of lymph node metastasis by PET/CT in patients with colorectal cancer.Methods: We retrospectively identified 864 patients who underwent preoperative PET/CT and colorectal cancer resection at Shizuoka General hospital from January 2017 to December 2019. We examined factors influencing the diagnostic accuracy of PET/CT to detect lymph node metastasis generally and lymph node metastasis for each TNM stage according to the UICC-TNM 8th edition.Results: The overall sensitivity and specificity of PET/CT to detect lymph node metastasis in patients with colorectal cancer were 61.2% and 75.9%, respectively. Distant lymph node metastasis was diagnosed more accurately than regional lymph node metastasis. “T category” (T1/T2 vs. T3/T4) was an independent factor affecting the lymph node metastasis diagnostic capability among patients negative for lymph node metastasis [p<0.01; odds ratio 2.20; 95% CI 1.28-3.84], while among patients positive for lymph node metastasis, “Tumor diameter” was significantly associated with the lymph node metastasis diagnostic capability on univariate analysis [p=0.02]. The sensitivity and specificity of PET/CT for Stage I (T1/T2, N0) were 82.5% and 84.6%, respectively. For more advanced tumors, the diagnostic ability to detect lymph node metastasis decreased. Conclusions: Disease-specific factors such as T category and tumor diameter significantly impacted on LN metastasis diagnosis by PET/CT in patients with colorectal cancer. We recommended the preoperative application of PET/CT only for the diagnosis of distant lymph node metastasis.
Extensive Tuberculous Lymphadenitis Mimicking Distant Lymph Node Metastasis on F-18FDG PET/CT in a Patient with a History of Malignant Melanoma