title: Length of capsular contact for diagnosing extraprostatic extension on prostate MRI: Assessment at an optimal threshold.
abstract: OBJECTIVE
  To evaluate the length of capsular contact of dominant lesions on multiparametric prostate magnetic resonance imaging (MRI) for predicting extraprostatic extension (EPE) and to determine a threshold value to apply in clinical practice.
  
  
  METHODS
  Ninety patients undergoing 3T prostate MRI before prostatectomy were included. Two independent readers (R1, R2) recorded for each lobe the presence or absence of capsular irregularity on T2 -weighted imaging (T2 WI) and of overt measurable EPE. Readers also recorded the length of capsular contact of each lobe's dominant lesion for T2 WI and the apparent diffusion coefficient (ADC) map. Based on prostatectomy specimens, EPE was recorded for each lobe and classified as focal (single focus ≤0.5 mm in depth) vs. established. Receiver operating characteristic analysis, logistic regression, and kappa coefficients were used to assess interpretive approaches on a side-specific basis.
  
  
  RESULTS
  The optimal thresholds were 6 mm and 7 mm of contact using T2 WI and ADC for any EPE, and 10 mm and 7 mm using T2 WI and ADC for nonfocal EPE (AUCs 81.0-82.5%). Capsular contact had higher sensitivity, yet lower specificity, than subjective interpretations for any EPE and for nonfocal EPE (all P ≤ 0.018, aside from any EPE for R2 using ADC). Length of contact exhibited more substantial gains in sensitivity (9-20% for any EPE; 34-41% for nonfocal EPE) than losses in specificity (6-13% for any EPE; 17-27% for nonfocal EPE) compared with subjective interpretations. Interreader agreement: 0.70 for assessments based on length of contact; 0.49-0.59 for subjective assessments.
  
  
  CONCLUSIONS
  Length of capsular contact of dominant lesions can improve interreader agreement and sensitivity for EPE compared with subjective features, with relatively mild specificity loss.
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, New York, New York, USA.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, New York, New York, USA.
authors.forename: Alampady K
authors.initials: AK
authors.lastname: Shanbhogue
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, New York, New York, USA.
authors.forename: Annie
authors.initials: A
authors.lastname: Wang
authors.affiliation: Department of Pathology, NYU School of Medicine, NYU Langone Medical Center, New York, New York, USA.
authors.forename: Max Xiangtian
authors.initials: MX
authors.lastname: Kong
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, New York, New York, USA.
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.affiliation: Department of Urology, Division of Urologic Oncology, NYU School of Medicine, NYU Langone Medical Center, New York, New York, USA.
authors.forename: Samir S
authors.initials: SS
authors.lastname: Taneja
mesh_terms: D000368:Aged; D000465:Algorithms; D019540:Area Under Curve; D003936:Diagnosis, Computer-Assisted; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000000981:diagnostic imaging / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen
keywords: MRI; diffusion-weighted imaging; prostate cancer; staging