A novel automated platform for quantifying the extent of skeletal tumour involvement in prostate cancer patients using the Bone Scan Index.
BACKGROUND
There is little consensus on a standard approach to analysing bone scan images. The Bone Scan Index (BSI) is predictive of survival in patients with progressive prostate cancer (PCa), but the popularity of this metric is hampered by the tedium of the manual calculation.


OBJECTIVE
Develop a fully automated method of quantifying the BSI and determining the clinical value of automated BSI measurements beyond conventional clinical and pathologic features.


METHODS
We conditioned a computer-assisted diagnosis system identifying metastatic lesions on a bone scan to automatically compute BSI measurements. A training group of 795 bone scans was used in the conditioning process. Independent validation of the method used bone scans obtained ≤3 mo from diagnosis of 384 PCa cases in two large population-based cohorts. An experienced analyser (blinded to case identity, prior BSI, and outcome) scored the BSI measurements twice. We measured prediction of outcome using pretreatment Gleason score, clinical stage, and prostate-specific antigen with models that also incorporated either manual or automated BSI measurements.


METHODS
The agreement between methods was evaluated using Pearson's correlation coefficient. Discrimination between prognostic models was assessed using the concordance index (C-index).


CONCLUSIONS
Manual and automated BSI measurements were strongly correlated (ρ=0.80), correlated more closely (ρ=0.93) when excluding cases with BSI scores≥10 (1.8%), and were independently associated with PCa death (p<0.0001 for each) when added to the prediction model. Predictive accuracy of the base model (C-index: 0.768; 95% confidence interval [CI], 0.702-0.837) increased to 0.794 (95% CI, 0.727-0.860) by adding manual BSI scoring, and increased to 0.825 (95% CI, 0.754-0.881) by adding automated BSI scoring to the base model.


CONCLUSIONS
Automated BSI scoring, with its 100% reproducibility, reduces turnaround time, eliminates operator-dependent subjectivity, and provides important clinical information comparable to that of manual BSI scoring.
Department of Laboratory Medicine, Lund University, Skåne University Hospital, Malmö, Sweden.
David
D
Ulmert
Reza
R
Kaboteh
Josef J
JJ
Fox
Caroline
C
Savage
Michael J
MJ
Evans
Hans
H
Lilja
Per-Anders
PA
Abrahamsson
Thomas
T
Björk
Axel
A
Gerdtsson
Anders
A
Bjartell
Peter
P
Gjertsson
Peter
P
Höglund
Milan
M
Lomsky
Mattias
M
Ohlsson
Jens
J
Richter
May
M
Sadik
Michael J
MJ
Morris
Howard I
HI
Scher
Karl
K
Sjöstrand
Alice
A
Yu
Madis
M
Suurküla
Lars
L
Edenbrandt
Steven M
SM
Larson
D000368:Aged; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000556:secondary*; D001842:Bone and Bones / Q000473:pathology*; D015331:Cohort Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D060787:Neoplasm Grading; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013669:Technetium Tc 99m Medronate; D051598:Whole Body Imaging / Q000379:methods*
D017430:Prostate-Specific Antigen; D013669:Technetium Tc 99m Medronate