title: Bone abnormal signal incidentally found in pre-biopsy diffusion-weighted MRI for suspected prostate cancer: what does it reflect?
abstract: OBJECTIVE
  To clarify the clinical significance of incidentally found diffusion-weighted MRI (DW-MRI)-positive findings on pre-biopsy MRI in patients with suspected prostate cancer.
  
  
  METHODS
  754 consecutive patients with suspected prostate cancer underwent pelvic MRI including DW-MRI. 43 DW-MRI-positive bone lesions were found in 27 patients. Imaging findings of these lesions were compared with the clinical diagnosis.
  
  
  RESULTS
  Of the 43 DW-MRI-positive bone lesions, 21 (48.8%) were diagnosed as metastatic prostate cancer. The remaining 22 (51.2%) were diagnosed as red bone marrow in 17, enchondroma in 1, ganglion in 1, osteoma in 1, fibrous dysplasia in 1 and bone infarction in 1. Enchondroma, ganglion, osteoma and fibrous dysplasia all showed T1-weighted imaging (T1WI) low and T2-weighted imaging (T2WI) high signals, while others, including prostate cancer metastases, showed T1WI and T2WI low signals. Of the 40 lesions with T1WI and T2WI low signals, metastatic prostate cancer had higher apparent diffusion coefficient values (median 0.42 × 10(-3) mm(2)/s) than other lesions (0.26 × 10(-3) mm(2)/s; p < 0.0001).
  
  
  CONCLUSIONS
  DW-MRI-positive bone lesions represent various coexisting types of bone lesions, including metastatic cancer in patients with suspected prostate cancer. T2WI findings and apparent diffusion coefficient values can be helpful in diagnosing metastatic cancer.
authors.affiliation: Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yachida
authors.forename: Soichiro
authors.initials: S
authors.lastname: Yoshida
authors.forename: Hideki
authors.initials: H
authors.lastname: Takeshita
authors.forename: Chigusa
authors.initials: C
authors.lastname: Sawamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanaka
authors.forename: Shiro
authors.initials: S
authors.lastname: Satoh
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Uchida
authors.forename: Junichiro
authors.initials: J
authors.lastname: Ishioka
authors.forename: Yoh
authors.initials: Y
authors.lastname: Matsuoka
authors.forename: Noboru
authors.initials: N
authors.lastname: Numao
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Koga
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Saito
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Fujii
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kihara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001859:Bone Neoplasms / Q000556:secondary*; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005266:Femoral Neoplasms / Q000556:secondary; D005269:Femur / Q000473:pathology*; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000473:pathology*; D011237:Predictive Value of Tests; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies