title: Variability in MRI vs. ultrasound measures of prostate volume and its impact on treatment recommendations for favorable-risk prostate cancer patients: a case series.
abstract: BACKGROUND
  Prostate volume can affect whether patients qualify for brachytherapy (desired size ≥20 mL and ≤60 mL) and/or active surveillance (desired PSA density ≤0.15 for very low risk disease). This study examines variability in prostate volume measurements depending on imaging modality used (ultrasound versus MRI) and volume calculation technique (contouring versus ellipsoid) and quantifies the impact of this variability on treatment recommendations for men with favorable-risk prostate cancer.
  
  
  METHODS
  We examined 70 patients who presented consecutively for consideration of brachytherapy for favorable-risk prostate cancer who had volume estimates by three methods: contoured axial ultrasound slices, ultrasound ellipsoid (height × width × length × 0.523) calculation, and endorectal coil MRI (erMRI) ellipsoid calculation.
  
  
  RESULTS
  Average gland size by the contoured ultrasound, ellipsoid ultrasound, and erMRI methods were 33.99, 37.16, and 39.62 mLs, respectively. All pairwise comparisons between methods were statistically significant (all p < 0.015). Of the 66 patients who volumetrically qualified for brachytherapy on ellipsoid ultrasound measures, 22 (33.33%) did not qualify on ellipsoid erMRI or contoured ultrasound measures. 38 patients (54.28%) had PSA density ≤0.15 ng/dl as calculated using ellipsoid ultrasound volumes, compared to 34 (48.57%) and 38 patients (54.28%) using contoured ultrasound and ellipsoid erMRI volumes, respectively.
  
  
  CONCLUSIONS
  The ultrasound ellipsoid and erMRI ellipsoid methods appeared to overestimate ultrasound contoured volume by an average of 9.34% and 16.57% respectively. 33.33% of those who qualified for brachytherapy based on ellipsoid ultrasound volume would be disqualified based on ultrasound contoured and/or erMRI ellipsoid volume. As treatment recommendations increasingly rely on estimates of prostate size, clinicians must consider method of volume estimation.
authors.forename: Yonina R
authors.initials: YR
authors.lastname: Murciano-Goroff
authors.forename: Luciant D
authors.initials: LD
authors.lastname: Wolfsberger
authors.forename: Arti
authors.initials: A
authors.lastname: Parekh
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Fennessy
authors.forename: Kemal
authors.initials: K
authors.lastname: Tuncali
authors.forename: Peter F
authors.initials: PF
authors.lastname: Orio
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Niedermayr
authors.forename: W Warren
authors.initials: WW
authors.lastname: Suh
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Devlin
authors.forename: Clare Mary C
authors.initials: CM
authors.lastname: Tempany
authors.forename: Emily H Neubauer
authors.initials: EH
authors.lastname: Sugar
authors.forename: Desmond A
authors.initials: DA
authors.lastname: O'Farrell
authors.forename: Graeme
authors.initials: G
authors.lastname: Steele
authors.forename: Michael
authors.initials: M
authors.lastname: O'Leary
authors.forename: Ivan
authors.initials: I
authors.lastname: Buzurovic
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Damato
authors.forename: Robert A
authors.initials: RA
authors.lastname: Cormack
authors.forename: Andriy Y
authors.initials: AY
authors.lastname: Fedorov
authors.affiliation: Brigham and Women's Hospital, Radiation Oncology, 75 Francis Street, Boston, MA 02115, USA. Pnguyen@lroc.harvard.edu.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Nguyen
mesh_terms: D001918:Brachytherapy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000628:therapy; D014463:Ultrasonography; D057832:Watchful Waiting