title: The Usefulness of Diffusion MRI in Detection of Lymph Node Metastases of Colorectal Cancer.
abstract: The aim of this study was to assess the sensitivity and specificity of preoperative diagnosis by diffusion magnetic resonance imaging (D-MRI) for lymph node metastasis of colorectal cancer. The b-value represents the diffusion factor (measured in s/mm(2)) and the strength of the diffusion gradients. The b-value used in this study was 1,000 s/mm(2). A total of 119 patients underwent D-MRI before resection of primary colorectal cancer (52 of the rectum, 67 of the colon) at our hospital between February 2005 and April 2006. Lymph node metastases judged by D-MRI were compared with postoperative pathological results. The form of lymph node metastasis was classified either as abundant or scarce type. The predictive values for lymph-node metastasis (sensitivity and specificity) by D-MRI were calculated from the result of this classification and lymph-node size. The study was divided into two periods: before the consensus meeting in January 2006, (n=79) (P-I), and after the adjustment of the criteria to improve the sensitivity and specificity based on the results of P-I (n=40) (P-II). Detection of lymph node metastasis using D-MRI in P-I had sensitivity of 61%, specificity of 73%, positive predictive value (PPV) of 55%, and negative predictive value (NPV) of 77%, while in P-II, these values improved to 79%, 95%, 94%, and 83%, respectively. Specificity and PPV for P-II were significantly higher than those for P-I (p<0.05). The diameter of lymph nodes judged to be metastatic on D-MRI (P-I vs. P-II: n=32 vs. 16) was 10.3±5.4 (3-28) vs. 9.1±3.0 (4-14) mm; 11.5±6.2 (4-28) vs. 9.2±3.1 (4-14) mm for truly positive nodes (n=18 vs. 15), and 6±3.8 (3-14) vs. 8 mm for false-positive nodes (n=14 vs. 1). On the other hand, lymph nodes judged negative by D-MRI (n=47 vs. 24) was 5.9±2.4 (3-16) vs. 5.7±2.8 (2-15) mm; 5.9±2.1 (3-16) vs. 5.3±2.1 (2-8) mm for truly negative (n=36 vs. 20), and 5.7±2.7 (3-12) vs. 7.8±4.9 (4-15) mm for false negative (n=11 vs. 4). As to the form of metastasis, all truly positive nodes were of the abundant type, and 6/11 (55%) in P-I and 1/4 (25%) in P-II false-negatives were of the scarce type. In conclusion, D-MRI seems useful for preoperative detection of metastatic lymph nodes in colorectal cancer, especially if the node is hyperintense and more than 9 mm in diameter.
authors: Department of Surgery, The Jikei University School of Medicine, Tokyo, Japan masatchmo1962@yahoo.co.jp.
authors: Masaichi
authors: M
authors: Ogawa
authors: Department of Radiology, The Jikei University School of Medicine, Tokyo, Japan.
authors: Noriatsu
authors: N
authors: Ichiba
authors: Department of Surgery, The Jikei University School of Medicine, Tokyo, Japan.
authors: Michiaki
authors: M
authors: Watanabe
authors: Department of Surgery, The Jikei University School of Medicine, Tokyo, Japan.
authors: Katsuhiko
authors: K
authors: Yanaga
mesh_terms: D000328:Adult; D000368:Aged; D003082:Colectomy; D015179:Colorectal Neoplasms / Q000556:secondary* / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging; D005188:False Negative Reactions; D005189:False Positive Reactions; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011300:Preoperative Care; D015203:Reproducibility of Results
keywords: Diffusion MRI; colorectal cancer; lymphnode metastasis