title: Apparent diffusion coefficient for lymph node characterization after chemoradiation therapy for locally advanced rectal cancer.
abstract: BACKGROUND
  Because further treatment plans depends on lymph node (LN) status after neoadjuvant chemoradiation therapy (CRT), the accurate characterization of LN is important.
  
  
  OBJECTIVE
  To evaluate the diagnostic performance of apparent diffusion coefficient (ADC) for LN characterization after CRT and to compare the performance with that of LN size.
  
  
  METHODS
  Fifty-three patients (36 men, 17 women; mean age, 58 years; age range, 34-79 years) who underwent CRT and subsequent surgery were included. All patients underwent 1.5-T magnetic resonance imaging (MRI). Each regional LN on post-CRT MRI was identified in consensus by two radiologists after reviewing the pre-CRT MRI. The ADC value and size in each LN was measured. To compare the mean ADC values and sizes of the metastatic and non-metastatic LNs after CRT, the t-test was used. To calculate the performance, a ROC curve analysis was performed. The histopathological examinations served as the reference standard.
  
  
  RESULTS
  A total of 115 LNs (29 metastatic and 86 non-metastatic) were matched and analyzed. The mean ADC of the metastatic LNs was significantly higher than that of the non-metastatic LNs (1.36 ± 0.27 × 10(-3)mm(2)/s; 1.13 ± 0.23 × 10(-3)mm(2)/s, P < 0.0001). The mean size of the metastatic LNs was also significantly larger than that of the non-metastatic LNs (5.6 ± 3.1; 3.9 ± 1.2, P = 0.0078). There was no significant difference between the areas under the curve of the ADC and size (0.742 [95% CI, 0.652-0.819]; 0.680 [0.586-0.764], respectively, P = 0.4090).
  
  
  CONCLUSIONS
  The performance of ADC for LN characterization after CRT was comparable to that of LN size.
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea radiresi@gmail.com.
authors.forename: Seung Ho
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.
authors.forename: Kyeong Hwa
authors.initials: KH
authors.lastname: Ryu
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.
authors.forename: Jung-Hee
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.
authors.forename: Yedaun
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Pathology, Seoul National University Bundang Hospital, Gyeonggi-do, Republic of Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Paik
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.
authors.forename: Suk Jung
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.
authors.forename: Hyun Kyung
authors.initials: HK
authors.lastname: Jung
authors.affiliation: Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.
authors.forename: Kwang Hwi
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology* / Q000528:radiation effects*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000628:therapy*; D015203:Reproducibility of Results; D016896:Treatment Outcome
keywords: Diffusion-weighted magnetic resonance imaging; apparent diffusion coefficient; lymph node; lymphatic metastasis; neoplasm; rectum