Efficacy of positron emission tomography in diagnosis of lateral lymph node metastases in patients with rectal Cancer: a retrospective study.

BACKGROUND: The presence of lateral pelvic lymph node (LLN) metastasis is an essential prognostic factor in rectal cancer patients. Thus, preoperative diagnosis of LLN metastasis is clinically important to determine the therapeutic strategy. The aim of this study was to evaluate the efficacy of preoperative positron emission tomography/computed tomography (PET/CT) in the diagnosis of LLN metastasis. METHODS: Eighty-four patients with rectal cancer who underwent LLN dissection at Osaka University were included in this study. The maximum standardized uptake value (SUVmax) of the primary tumor and LLN were preoperatively calculated using PET/CT. Simultaneously, the short axis of the lymph node was measured using multi-detector row computed tomography (MDCT). The presence of metastases was evaluated by postoperative pathological examination. RESULTS: Of the 84 patients, LLN metastases developed in the left, right, and both LLN regions in 6, 7, and 2 patients, respectively. The diagnosis of the metastases was predicted with a sensitivity of 82%, specificity of 93%, positive predictive value of 58%, negative predictive value of 98%, false positive value of 7%, and false negative value of 18% when the cutoff value of the LLN SUVmax was set at 1.5. The cutoff value of the short axis set at 7 mm on MDCT was most useful in diagnosing LLN metastases, but SUVmax was even more useful in terms of specificity. CONCLUSIONS: The cutoff value of 1.5 for lymph node SUVmax in PET is a reasonable measure to predict the risk of preoperative LLN metastases in rectal cancer patients.

Preoperative evaluation of venous anatomy in laparoscopic complete mesocolic excision for right colon cancer.

PURPOSE: This study evaluated the venous variations of the right colon using preoperative three-dimensional computed tomography (3D-CT), and to investigate its usefulness in laparoscopic complete mesocolic excision (CME) for right colon cancer. METHODS: 3D-CT was performed prior to surgery in 81 consecutive patients with right colon cancer. RESULTS: Laparoscopic right hemicolectomy was performed without conversion to open surgery in all cases (100 %). All 81 patients had a single ileocolic vein (ICV). The ICV flowed into the superior mesenteric vein (SMV) in 98 % of patients and the gastrocolic trunk (GCT) in 2 % of patients. The right colic vein (RCV) was absent in 6 % of patients. One RCV was present in 88 % of patients and two were present in 6 % of patients. The main RCV flowed into the GCT in 84 % of patients and the SMV in 10 % of patients. The superior RCV was present in 21 % of patients, and all cases flowed into the GCT. One middle colic vein (MCV) was present in 49 % of patients, two in 46 %, and three in 5 % of patients. The main MCV flowed into the SMV in 68 % of patients, GCT in 20 %, jejunal vein in 6 %, inferior mesenteric vein in 5 %, and the splenic vein in 1 % of patients. The GCT was present in 88 % of patients. CONCLUSIONS: Although the venous tributaries of the right colon are variable, preoperative 3D-CT is informative and helpful for surgeons performing laparoscopic CME for right colon cancer.

Efficacy of PET/CT in diagnosis of regional lymph node metastases in patients with colorectal cancer: retrospective cohort study.

BACKGROUND: Endoscopic and transanal local resection without lymph node dissection are treatment options for patients with a low risk of lymph node metastasis; however, some patients might have undiagnosed lymph node metastases before surgery. This retrospective study aimed to evaluate the efficacy of preoperative PET/CT for diagnosing regional lymph node metastasis. METHODS: Patients who underwent curative resection with lymph node dissection for colorectal cancer at Osaka University between January 2012 and December 2015 were included. The cut-off values appropriate for diagnosing lymph node metastasis were calculated by way of a receiver operating characteristic (ROC) curves from maximum standard unit value (SUVmax) of main tumour, and lymph node short axis, and SUVmax of lymph node. The cut-off values of primary tumour SUVmax: 7, short-axis diameter of the lymph node at 7 mm, and lymph node SUVmax at 1.5 were set. RESULT: A total of 541 patients were included. Regional lymph node metastases were confirmed in resected specimens from 187 patients (35 per cent). With a primary tumour SUVmax of 7 used as a cut-off value, the sensitivity and specificity of regional lymph node metastasis were 70.1 per cent and 45.5 per cent respectively. With a cut-off short-axis diameter of the regional lymph node of 7 mm, the sensitivity and specificity of regional lymph node metastasis were 75.2 per cent and 82.6 per cent respectively, and with a cut-off regional lymph node SUVmax of 1.5, the sensitivity and specificity of regional lymph node metastasis were 78.6 per cent and 96.8 per cent respectively. When the diagnostic criteria were defined by a lymph node short-axis diameter of 7 mm or SUVmax of 1.5, the sensitivity and specificity were 87.4 per cent and 81.8 per cent respectively. CONCLUSION: Preoperative PET/CT is a useful modality for evaluating regional lymph node metastasis in patients with colorectal cancer.