title: Potential of quantitative susceptibility mapping for detection of prostatic calcifications.
abstract: To evaluate whether quantitative susceptibility (QSM) may be used as an alternative to computed tomography (CT) to detect calcification in prostate cancer patients.
  
  
  
  Susceptibility map calculation was performed using 3D gradient echo magnetic resonance imaging (MRI) data from 26 patients measured at 3T who previously received a planning CT of the prostate. Phase images were unwrapped using Laplacian-based phase unwrapping, the background field was removed with the V-SHARP method, and susceptibility maps were calculated with the iLSQR method. Two blinded readers were asked to identify peri- and intraprostatic calcifications.
  
  
  
  Average mean and minimum susceptibility values (referenced to iliopsoas muscle) of calcifications were -0.249 ± 0.179 ppm and -0.551 ± 0.323 ppm, and average mean and maximum intensities in CT images were 319 ± 164 HU and 679 ± 392 HU. Twenty-one and 17 out of 22 prostatic calcifications were identified using susceptibility maps and magnitude images, respectively, as well as more than half of periprostatic phleboliths depicted by CT. Calcifications in the prostate and its periphery were quantitatively differentiable from noncalcified prostate tissue in CT (mean values for calcifications / for noncalcified tissue: 71 to 649 / -1 to 83 HU) and in QSM (mean values for calcifications / for noncalcified tissue: -0.641 to 0.063 / -0.046 to 0.181 ppm). Moreover, there was a significant correlation between susceptibility values and CT image intensities for calcifications (P < 0.004).
  
  
  
  Prostatic calcifications could be well identified with QSM. Susceptibility maps can be easily obtained from clinical prostate MR protocols that include a 3D gradient echo sequence, rendering it a promising technique for detection and quantification of intraprostatic calcifications.
  
  
  
  1 J. Magn. Reson. Imaging 2017;45:889-898.
authors.affiliation: German Cancer Research Center (DKFZ), Department of Medical Physics in Radiology, Heidelberg, Germany.
authors.forename: Sina
authors.initials: S
authors.lastname: Straub
authors.affiliation: German Cancer Research Center (DKFZ), Department of Medical Physics in Radiology, Heidelberg, Germany.
authors.forename: Frederik B
authors.initials: FB
authors.lastname: Laun
authors.affiliation: German Cancer Research Center (DKFZ), Department of Medical Physics in Radiology, Heidelberg, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Emmerich
authors.affiliation: German Cancer Research Center (DKFZ), Department of Radiology, Heidelberg, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Jobke
authors.affiliation: German Cancer Research Center (DKFZ), Clinical Cooperation Unit Radiation Oncology, Heidelberg, Germany.|Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Hauswald
authors.affiliation: Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Katayama
authors.affiliation: Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Herfarth
authors.affiliation: German Cancer Research Center (DKFZ), Department of Radiology, Heidelberg, Germany.
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schlemmer
authors.affiliation: German Cancer Research Center (DKFZ), Department of Medical Physics in Radiology, Heidelberg, Germany.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
authors.affiliation: German Cancer Research Center (DKFZ), Department of Radiology, Heidelberg, Germany.
authors.forename: Christian H
authors.initials: CH
authors.lastname: Ziener
authors.affiliation: German Cancer Research Center (DKFZ), Department of Radiology, Heidelberg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Bonekamp
authors.affiliation: German Cancer Research Center (DKFZ), Department of Radiology, Heidelberg, Germany.
authors.forename: Matthias C
authors.initials: MC
authors.lastname: Röthke
mesh_terms: D000328:Adult; D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D005240:Feasibility Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011230:Precancerous Conditions / Q000000981:diagnostic imaging* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: calcification; multiparametric magnetic resonance imaging; prostate cancer; quantitative susceptibility mapping