Measurement of prostate tumour volume can inform prognosis and treatment selection, including an assessment of the
suitability and feasibility of focal therapy, which can potentially spare patients the deleterious side effects of radical
treatment. Prostate biopsy is the clinical standard for diagnosis but provides limited information regarding tumour
volume due to sparse tissue sampling. A non-invasive means for accurate determination of tumour burden could be of
clinical value and an important step toward reduction of overtreatment. Multi-parametric magnetic resonance imaging
(MPMRI) is showing promise for prostate cancer diagnosis. However, the accuracy and inter-observer variability of
prostate tumour volume estimation based on separate expert contouring of T2-weighted (T2W), dynamic contrastenhanced
(DCE), and diffusion-weighted (DW) MRI sequences acquired using an endorectal coil at 3T is currently
unknown. We investigated this question using a histologic reference standard based on a highly accurate MPMRIhistology
image registration and a smooth interpolation of planimetric tumour measurements on histology. Our results
showed that prostate tumour volumes estimated based on MPMRI consistently overestimated histological reference
tumour volumes. The variability of tumour volume estimates across the different pulse sequences exceeded interobserver
variability within any sequence. Tumour volume estimates on DCE MRI provided the lowest inter-observer
variability and the highest correlation with histology tumour volumes, whereas the apparent diffusion coefficient (ADC)
maps provided the lowest volume estimation error. If validated on a larger data set, the observed correlations could
support the development of automated prostate tumour volume segmentation algorithms as well as correction schemes
for tumour burden estimation on MPMRI.
Accurate pathology assessment of post-prostatectomy specimens is important to determine the need for and to guide
potentially life-saving adjuvant therapy. Digital pathology imaging is enabling a transition to a more objective quantification of some surgical pathology assessments, such as tumour volume, that are currently visually estimated by
pathologists and subject to inter-observer variability. One challenge for tumour volume quantification is the traditional 3–5 mm spacing of images acquired from sections of radical prostatectomy specimens. Tumour volume estimates may benefit from a well-motivated approach to inter-slide tumour boundary interpolation. We implemented and tested a level set-based interpolation method and found that it produced 3D tumour surfaces that may be more biologically plausible than those produced via a simpler nearest-slide interpolation. We found that the simpler method produced larger tumour volumes, compared to the level set method, by a median factor of 2.3. For contexts where only tumour volume is of interest, we determined that the volumes produced via the simpler method can be linearly adjusted to the level setproduced volumes. The smoother surfaces from level set interpolation yielded measurable differences in tumour boundary location; this may be important in several clinical/research contexts (e.g. pathology-based imaging validation for focal therapy planning).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.