Accuracy of high-resolution magnetic resonance imaging in diagnosis of the lymph node metastases and stage of rectal cancer / 中华消化外科杂志

ABSTRACT

Objective To investigate the accuracy of high-resolution magnetic resonance imaging (MRI) in diagnosis of the lymph nodes metastases (LNMs) and stage of rectal cancer (RC).Methods The retrospective cross-sectional study was conducted.The clinicopathological data of 65 patients with RC who were admitted to the Peking University People's Hospital between April 2014 and April 2016 were collected.The results of postoperative pathological examinationof 65 patients with RC,24 had positive LNMs and 41 had negative LNMs;N0,N1 and N2 were respectively detected in 41,14 and 10 patients.Imaging data were captured using 3.0-Tesla MRI and body phased-array coil.Diagnostic criteria for LNMs of RCcriterion 1irregular lymph node boundaries and signal characteristics were not considered;criterion 2heterogeneous signal of lymph nodes and boundary characteristics were not considered;criterion 3irregular lymph node boundaries and / or heterogeneous signal of lymph nodes.The American Joint Committee on Cancer (AJCC) cancer staging manual (7th edition) have established the N staging scheme for RC.Lymph nodes distribution according to the rectal lymphatic drainageD1was located in fascia of the mesorectum;D1a above the level of tumor;D1b at the level of tumor;D1c under the level of tumor;D2 around the superior rectal artery and root of inferior mesenteric artery;D3 on the side of pelvic cavity.Observation indicators(1) Efficiency and comparison of LNMs of RC diagnosed by high-resolution MRI according to the 3 criteria (postoperative pathological result as a gold standard).(2) Efficiency and comparison of N stage of RC diagnosed by high-resolution MRIaccording to the 3 criteria (postoperative pathological result as a gold standard).(3) Efficiency of LNMs of RC diagnosed by high-resolution MRI according to the maximum short diameter of lymph nodes① maximum short diameter distribution of positive and negative LNMs of RC;②sensitivity,specificity,accuracy and consistency of LNMs diagnosed using different maximum short diameter of lymph nodes as a threshold (postoperative pathological result as a gold standard);③ comparison of accuracy of LNMs diagnosed using maximum short diameter of lymph nodes with highest diagnostic accuracy as a threshold and using the 3 criteria;④ sensitivity,specificity,accuracy and consistency (postoperative pathological result as a gold standard) of LNMs diagnosed using maximum short diameter of lymph nodes with highest diagnostic accuracy as a threshold combined with the highest efficiency in the (1),and its comparison in accuracy of LNMs with highest diagnostic accuracy as a threshold.(4) Distribution of LNMs of RC diagnosed by high-resolution MRI according to the 3 criteria.(5) Follow-up situations.Follow-up using outpatient examination and telephone interview was performed to detect patients' postoperative survival up to October 2016.The sensitivity,specificity,accuracy and comparison of ratio were respectively done by the chi-square test.Kappa test was used for consistency,tκ ≤ 0.40was used as low consistency,0.40＜κ≤0.60 as moderate consistency,0.60＜κ≤0.80 as higher consistency,and κ＞ 0.80 very high consistency.Results (1) Efficiency and comparison of LNMs of RC diagnosed by highresolution MRIaccording to the 3 criteriaaccuracies of LNMs of RC diagnosed by high-resolution MRI according to the criterion 1,2 and 3 were respectively 93.8％,87.7％ and 90.8％,showing very.high,higher and very high consistencies compared with postoperative pathological results (κ =0.87,0.74,0.81,P＜0.05),and with no statistically significant difference in diagnostic accuracy among them (x2=1.495,P＞0.05).(2) Efficiency and comparison of N stage of RC diagnosed by high-resolution MRI according to the 3 criteriaaccuracies of N stage of RC diagnosed by high-resolution MRI according to the criterion 1,2 and 3 were respectively 87.7％,83.1％ and 84.6％,showing the same higher consistencies compared with postoperative pathological result (κ =0.77,0.68,0.72,P＜0.05),and with no statistically significant difference in N stage among them (x2=0.567,P＞0.05).(3) Efficiency of LNMs of RC diagnosed by high-resolution MRI according to the maximum short diameter of lymph nodes① maximum short diameter distribution of positive and negative LNMs of RCmaximum short diameter ranges were respectively 3-18 mm in positive LNMs and 1-9 mm in negative LNMs,and maximum short diameter ＜3 mm and ≥ 10 mm were respectively negative and positive LNMs.② Efficiency of LNMs of RC diagnosed using different maximum short diameter of lymph nodes as a thresholddiagnostic accuracy of 70.8％was the highest when maximum short diameter ＞7 mm was used as a standard of positive LNMs,showing a low consistency compared with postoperative pathological result (κ =0.29,P＜0.05).③ Comparison of accuracy of LNMs diagnosed using maximum short diameter of lymph nodes ＞7 mm as a threshold and using the 3 criteriathere was a statistically significant difference among them (x2 =15.637,P＜0.05);accuracies of LNMs of RC diagnosed by high-resolution MRI according to the criterion 1,2 and 3 were higher than that diagnosed using maximum short diameter of lymph nodes ＞7 mm as a threshold (x2 =10.354,5.656,6.923,P＜0.05).④Comparison of accuracy of LNMs diagnosed using maximum short diameter of lymph nodes ＞7 mm combined with the criterion 3 as a threshold and using maximum short diameter ＞7 mm as a thresholdthe criterion 3 was used as a threshold because there was no statistically significant difference in diagnostic accuracy among the 3 criteria (P＞ 0.05).Diagnostic accuracy was 78.5％ when maximum short diameter ＞7 mm combined with the criterion 3 as a threshold,showing a low consistency compared with postoperative pathological result (κ =0.36,P＜0.05),with no statistically significant difference in diagnostic accuracy compared with maximum short diameter ＞ 7 mm as a threshold (x2=0.154,P＞0.05).(4) Distribution of LNMs of RC diagnosed by high-resolution MRI according to the 3 criteriapositive LNMs of RC diagnosed by high-resolution MRI located mostly in D1 (76.1％-83.1％)and D1b(77.8％-81.4％).(5) Follow-up situationsof 65 patients,54 were followed up for 6-25 months,with a median time of 14 months.During the follow-up,7 patients had distant metastases and 47 had tumor-free survival.Conclusions There are higher accuracies of LNMs and N stage of RC diagnosed using preoperative highresolution MRI.Diagnostic accuracy of LNMs of RC cannot be improved when characteristics of lymph node morphology and size are used as a diagnostic standard.The positive LNMs of RC locate mostly in D1 and Dib.