Non-invasive MR assessment of the microstructure and microcirculation in regional lymph nodes for rectal cancer: a study of intravoxel incoherent motion imaging.

BACKGROUND: The aim of this study is to evaluate the microstructure and microcirculation of regional lymph nodes (LNs) in rectal cancer by using non-invasive intravoxel incoherent motion MRI (IVIM-MRI), and to distinguish metastatic from non-metastatic LNs by quantitative parameters. METHODS: All recruited patients underwent IVIM-MRI (b = 0, 5, 10, 20, 30, 40, 60, 80, 100, 150, 200, 400, 600, 1000, 1500 and 2000 s/mm2) on a 3.0 T MRI system. One hundred sixty-eight regional LNs with a short-axis diameter equal to or greater than 5 mm from 116 patients were evaluated by two radiologists independently, including 78 malignant LNs and 90 benign LNs. The following parameters were assessed: the short-axis diameter (S), long-axis diameter (L), short- to long-axis diameter ratio (S/L), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion factor (f). Intraclass correlation coefficients (ICCs) were calculated to assess the interobserver agreement between two readers. Receiver operating characteristic curves were applied for analyzing statistically significant parameters. RESULTS: Interobserver agreement of IVIM-MRI parameters between two readers was excellent (ICCs> 0.75). The metastatic group exhibited higher S, L and D (P < 0.001), but lower f (P < 0.001) than the non-metastatic group. The area under the curve (95% CI, sensitivity, specificity) of the multi-parameter combined equation for D, f and S was 0.811 (0.744~0.868, 62.82%, 87.78%). The diagnostic performance of the multi-parameter model was better than that of an individual parameter (P < 0.05). CONCLUSION: IVIM-MRI parameters provided information about the microstructure and microcirculation of regional LNs in rectal cancer, also improved diagnostic performance in identifying metastatic LNs.

[Diagnostic accuracy of 3.0T high-resolution MRI for assessment mesorectal lymph node metastases in patients with rectal cancer].

OBJECTIVE: To evaluate the diagnostic value of 3.0T high-resolution MRI in mesorectal lymph node metastasis of rectal cancer. METHODS: The images and postoperative pathological data of patients with pathologically diagnosed rectal cancer who underwent prospective 3.0T two dimensional high-resolution MRI rectal examinations and surgery within two weeks after MRI examination at the First Affiliated Hospital, Sun Yat-sen University from November 2015 to November 2016 were retrospectively collected. Patients who received preoperative neoadjuvant therapy and those who did not undergo operation after MRI examination were excluded. The MRI sequences included high-resolution sagittal, coronal and oblique axial T2 weighted image (T2WI) (repetition time/echo time, 3000-4000 ms/77-87 ms; slice thickness/gap, 3 mm/0 mm; field of view, 18-22 cm). Two abdominal MRI radiologists independently assessed the morphology, margin, signal of all visible mesorectal nodes, measured their minor axes (three times for each radiologist) and gave estimation of the malignancy. The criteria of metastatic nodes on high-resolution MRI T2WI were nodes with irregular shape, ill-defined border and/or heterogeneous signal. The results of MRI diagnosis were compared with postoperative pathology. The sensitivity, specificity, accuracy, positive predictive value(PPV) and negative predictive value(NPV) of mesorectal nodes and nodes with different short-axis diameter ranges were calculated to evaluate the diagnostic efficiency of high-resolution MRI. Kappa statistics was used to evaluate the agreement for per node and for per patient between high-resolution MRI and pathological results. A Kappa value of 0-0.20 indicated poor agreement; 0.21-0.40 fair agreement; 0.41-0.60 moderate agreement; 0.61-0.80 good agreement; and 0.81-1.00 excellent agreement. RESULTS: A total of 81 patients were enrolled in the retrospective cohort study, including 50 males and 31 females with age of (59.3±11.1) years. Histopathology showed 1 case of well differentiated adenocarcinoma, 63 of moderately differentiated adenocarcinoma, 9 of moderately to poorly differentiated adenocarcinoma, 2 of poorly differentiated adenocarcinoma, 3 of mucinous adenocarcinoma and 3 of tubulovillous adenocarcinoma. Histopathological staging showed 2 cases in T1 stage, 20 in T2 stage, 45 in T3 stage and 14 in T4 stage; 34 in N0 stage, 40 in N1 stage and 7 in N2 stage; 76 in M0 stage and 5 in M1 stage. A total of 377 nodes were included in the node-by-node evaluation, of which 168 (44.6%) nodes were metastatic from 58.0% (47/81) patients. The median short-axis diameter was 5.4(2.4-18.6) mm in metastatic nodes, which was significantly larger than 3.8 (2.0-8.7) mm in non-metastatic nodes[Z=10.586, P=0.000]. The sensitivity, specificity, accuracy, PPV and NPV were 74.4% (125/168), 94.7% (198/209), 85.7% (323/377), 91.9% (125/136) and 82.2% (198/241), respectively. The Kappa values between high-resolution MRI and histopathological diagnosis for node-by-node and patient-by-patient were 0.71 and 0.70 respectively, indicating good agreements. Fourteen nodes >10 mm were all metastatic. The results of high-resolution MRI for nodal status were consistent with the results of histopathological diagnosis, and the sensitivity, accuracy and PPV were all 100.0%. Among 124 nodes with short-axis diameter of 5-10 mm, 95 (76.6%) were metastatic, and the sensitivity, specificity, accuracy, PPV and NPV were 78.9% (75/95), 86.2% (25/29), 80.6% (100/124), 94.9% (75/79) and 55.6% (25/45), respectively. The agreement was fair (Kappa value 0.55) between high-resolution MRI and histopathological diagnosis. Among 239 nodes with short-axis diameter ≤5 mm, 59(24.7%) were metastatic, and the sensitivity, specificity, accuracy, PPV and NPV were 61.0% (36/59), 96.1%(173/180), 87.4%(209/239), 83.7%(36/43) and 88.3%(173/196), respectively. The agreement was good (Kappa value 0.63) between high-resolution MRI and histopathological diagnosis. CONCLUSION: Rectal high-resolution MRI has good diagnostic value for estimating metastatic mesorectal nodes by evaluating the morphology, margin and signal of nodes.

Quality assessment of clinical guidelines in China: 1993 - 2010.

BACKGROUND: Clinical practice guidelines (CPGs) play an important role in healthcare in China as well as in the world. However, the current status and trends of Chinese CPGs are unknown. The aim of this study was to systematically review the present situation and the quality of Chinese CPGs published in the peer-reviewed medical literature. METHODS: To identify Chinese CPGs, a systematic search of relevant literature databases (CBM, WANFANG, VIP, and CNKI) was performed for the period January 1978 to December 2010. We used the AGREE II instrument to assess the quality of the included guidelines. RESULTS: We evaluated 269 guidelines published in 115 medical journals from 1993 to 2010 and produced by 256 different developers. Only four guidelines (1%) described the systematic methods for searching and selecting the evidence, 14 (5%) guidelines indicated an explicit link between the supporting evidence and the recommendations, only one guideline used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Thirty-one guidelines (12%) mentioned updates and the average frequency of update was 5.5 years; none described a procedure for updating the guideline. From the assessment with the Appraisal of Guidelines for Research and Ecaluation II (AGREE II), the mean scores were low for the domains "scope and purpose" (19%) and "clarity of presentation" (26%) and very low for the other domains ("rigour of development" 7%, "stakeholder involvement" 8%, "applicability" 6% and "editorial independence" 2%). CONCLUSIONS: Compared with other studies on the quality of guidelines assessed with the AGREE instrument in other countries, Chinese CPGs received lower scores, which indicates a relatively poor quality of the guidelines. However, there was some increase over time.