To investigate the value of ¹⁸F-FDG PET/CT metabolic parameters in predicting perineural invasion (PNI) in patients with non-metastatic rectal cancer.

From August 2012 to April 2020, 81 patients (51 males, 30 females, median age: 63 years) who received PET/CT examination and pathologically confirmed as rectal cancer in the Affiliated Hospital of Qingdao University were retrospectively analyzed. The ¹⁸F-FDG PET/CT metabolic parameters including SUV_max, metabolic tumor volume (MTV) and total lesion glycolysis (TLG), and clinicopathological factors including gender, age, carcinoembryonic antigen (CEA), carbohydrate antigen (CA)19-9, maximum tumor diameter, degree of differentiation, T stage, lymph node metastasis, and TNM stage were recorded. Mann-Whitney U test and χ² test were used to compare the differences of each parameter between PNI positive group and PNI negative group. Multivariate logistic regression was used to analyze the independent predictor of positive PNI. ROC curve was used to analyze its predictive efficacy.

Of 81 patients, 32(39.51%) were PNI positive and 49(60.49%) were PNI negative. There were significant differences of T stage (χ²=10.73, P=0.010), lymph node metastasis (χ²=6.21, P=0.013), TNM stage (χ²=7.61, P=0.022), MTV (14.6(10.4, 24.7)and 9.0(5.4, 14.5) cm³; U=-3.48, P=0.001) and TLG (108.588(72.749, 182.707) and 65.365(35.593, 117.682) g; U=-2.79, P=0.005) between PNI positive group and PNI negative group. Multivariate logistic regression analysis showed that MTV was the independent predictor of positive PNI in non-metastatic rectal cancer patients (odds ratio (OR)=1.130, 95% CI: 1.025-1.245, P=0.014). The optimal threshold of MTV was 9.53 cm³ and AUC was 0.73 with the sensitivity of 81.82%(27/33) and the specificity of 59.18%(29/49).

¹⁸F-FDG PET/CT metabolic parameter MTV can predict PNI in non-metastatic rectal cancer with high sensitivity.

Rectal neoplasms; Neoplasm Invasiveness; Peripheral nerves; Positron-emission tomography; Tomography, X-ray computed; Fluorodeoxyglucose F18