Prostate Cancer Volume Estimation by Combining Magnetic Resonance Imaging and Targeted Biopsy Proven Cancer Core Length: Correlation with Cancer Volume.
OBJECTIVE
Multiparametric magnetic resonance imaging often underestimates or overestimates pathological cancer volume. We developed what is to our knowledge a novel method to estimate prostate cancer volume using magnetic resonance/ultrasound fusion, biopsy proven cancer core length.


METHODS
We retrospectively analyzed the records of 81 consecutive patients with magnetic resonance/ultrasound fusion, targeted biopsy proven, clinically localized prostate cancer who underwent subsequent radical prostatectomy. As 7 patients each had 2 visible lesions on magnetic resonance imaging, 88 lesions were analyzed. The dimensions and estimated volume of visible lesions were calculated using apparent diffusion coefficient maps. The modified formula to estimate cancer volume was defined as the formula of vertical stretching in the anteroposterior dimension of the magnetic resonance based 3-dimensional model, in which the imaging estimated lesion anteroposterior dimension was replaced by magnetic resonance/ultrasound targeted, biopsy proven cancer core length. Agreement of pathological cancer volume with magnetic resonance estimated volume or the novel modified volume was assessed using a Bland-Altman plot.


RESULTS
Magnetic resonance/ultrasound fusion, biopsy proven cancer core length was a stronger predictor of the actual pathological cancer anteroposterior dimension than magnetic resonance estimated lesion anteroposterior dimension (r = 0.824 vs 0.607, each p <0.001). Magnetic resonance/ultrasound targeted, biopsy proven cancer core length correlated with pathological cancer volume (r = 0.773, p <0.001). The modified formula to estimate cancer volume demonstrated a stronger correlation with pathological cancer volume than with magnetic resonance estimated volume (r = 0.824 vs 0.724, each p <0.001). Agreement of modified volume with pathological cancer volume was improved over that of magnetic resonance estimated volume on Bland-Altman plot analysis. Predictability was more enhanced in the subset of lesions with a volume of 2 ml or less (ie if spherical, the lesion was approximately 16 mm in diameter).


CONCLUSIONS
Combining magnetic resonance estimated cancer volume with magnetic resonance/ultrasound fusion, biopsy proven cancer core length improved cancer volume predictability.
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California; Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Toru
T
Matsugasumi
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Eduard
E
Baco
Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Suzanne
S
Palmer
Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Manju
M
Aron
Imaging-based Computational Biomedicine Laboratory, Graduate School of Information Science, Nara Institute of Science and Technology, Nara, Japan.
Yoshinobu
Y
Sato
Imaging-based Computational Biomedicine Laboratory, Graduate School of Information Science, Nara Institute of Science and Technology, Nara, Japan.
Norio
N
Fukuda
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Evren
E
Süer
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Jean-Christophe
JC
Bernhard
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California; Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Hideo
H
Nakagawa
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California; Urology Department, King Abdulaziz University, Jeddah, Saudi Arabia.
Raed A
RA
Azhar
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California.
Inderbir S
IS
Gill
USC Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, California. Electronic address: ukimura@usc.edu.
Osamu
O
Ukimura
D000368:Aged; D000369:Aged, 80 and over; D062005:Biopsy, Large-Core Needle; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D047368:Tumor Burden
biopsy; magnetic resonance imaging; prognosis; prostatic neoplasms; tumor burden