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 examination:of 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 RC:criterion 1:irregular lymph node boundaries and signal characteristics were not considered;criterion 2:heterogeneous signal of lymph nodes and boundary characteristics were not considered;criterion 3:irregular 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 drainage:D1was 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 nodes:① 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 criteria:accuracies 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 criteria:accuracies 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 nodes:① maximum short diameter distribution of positive and negative LNMs of RC:maximum 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 threshold:diagnostic 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 criteria:there 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 threshold:the 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 criteria:positive 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 situations:of 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.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the accuracy of 3.0T high-resolution magnetic resonance imaging(MRI) in definition of tumor invasion depth staging (T staging) before operation.</p><p><b>METHODS</b>Clinical and radiographic data of 49 rectal cancer patients who underwent radical resection within two weeks after 3.0 T high-resolution MRI examination without preoperative neoadjuvant chemotherapy in Peking University People's Hospital between February 2015 and November 2015 were retrospectively collected. Two radiologists reviewed the MRI imagines and evaluated the location and T staging of rectal cancer independently(radiologist A and B). The kappa statistics was used to evaluate the interobserver agreement, and kappa value greater than 0.81 indicated excellent agreement. The accuracy, sensitivity and specificity of high-resolution MRI in definition of rectal cancer T staging were assessed with pathological result as golden standard.</p><p><b>RESULTS</b>According to pathological result of 49 rectal cancer patients, 3 were pT1, 17 were pT2, 22 were pT3, and 7 were pT4a. In 2 cases of mucinous adenocarcinoma, MRI T2WI showed focal or diffuse significantly higher signal close to perirectal fat. And in other 47 patients of non-mucinous adenocarcinoma, MRI T2WI showed equal or higher signal compared with pelvic muscle. Interobserver agreement was excellent in diagnosis of T staging of rectal cancer with 3.0T high-resolution MRI(Kappa=0.87). The accuracy, sensitivity and specificity of both radiologists for T1 staging was 95.9%(47/49), 1/3 and 100%(46/46) respectively, besides, 1 case was both diagnosed correctly and 2 cases were overstaged. For 2 radiologists, the accuracy of T2 staging was 87.8%(43/49) and 91.8%(45/49) respectively, the sensitivity was both 88.2%(15/17), and the specificity was 87.5%(28/32) and 93.5%(30/32) respectively, besides, 15 cases were both diagnosed correctly and 2 cases were overstaged. The accuracy for T3 staging was 89.8%(44/49) and 93.9%(46/49) respectively, the sensitivity was 86.4%(19/22) and 95.5%(21/22) respectively, and the specificity was both 92.6%(25/27). Radiologist A made correct diagnosis for 19 cases, understaged 2 cases and overstaged 1 case. Radiologist B made correct diagnosis for 21 cases and only overstaged 1 case. The accuracy, sensitivity and specificity of both radiologists for T4a staging was 98.0%(48/49), 7/7 and 97.6%(41/42) respectively, besides, 7 cases were both diagnosed correctly. The overall accuracy of T staging was 85.7%(42/49) and 89.8%(44/49) by two radiologists respectively. The accuracy for differentiating T1/T2 from T3/T4 was 91.8%(45/49) and 95.9%(47/49) by two radiologists respectively. Radiologist A overstaged 2 cases and understaged 2 cases, and radiologist B overstaged 2 cases.</p><p><b>CONCLUSION</b>High-resolution MRI can accurately evaluate preoperative T staging of rectal cancer and help select the high-risk rectal cancer patients with over T3 to receive neoadjuvant treatment.</p>