Computational imaging reveals shape differences between normal and malignant prostates on MRI

Abstract

We seek to characterize differences in the shape of the prostate and the central gland (combined central and transitional zones) between men with biopsy confirmed prostate cancer and men who were identified as not having prostate cancer either on account of a negative biopsy or had pelvic imaging done for a non-prostate malignancy. T2w MRI from 70 men were acquired at three institutions. The cancer positive group (PCa+) comprised 35 biopsy positive (Bx+) subjects from three institutions (Gleason scores: 6-9, Stage: T1-T3). The negative group (PCa−) combined 24 biopsy negative (Bx−) from two institutions and 11 subjects diagnosed with rectal cancer but with no clinical or MRI indications of prostate cancer (Cl−). The boundaries of the prostate and central gland were delineated on T2w MRI by two expert raters and were used to construct statistical shape atlases for the PCa+, Bx− and Cl− prostates. An atlas comparison was performed via per-voxel statistical tests to localize shape differences (significance assessed at p < 0.05). The atlas comparison revealed central gland hypertrophy in the Bx− subpopulation, resulting in significant volume and posterior side shape differences relative to PCa+ group. Significant differences in the corresponding prostate shapes were noted at the apex when comparing the Cl− and PCa+ prostates.Multi-parametric magnetic resonance imaging (MRI) plays an essential role in the management of prostate cancer (PCa), improving localization and local staging of the disease 1,2 . In addition to providing structural and functional images of the prostate, prostate MRI has also revealed differences in cancers based on their localization in the anatomic subregions of the prostate 3 . Cancers localized in the peripheral zone are more frequent 4 and have a different MRI appearance 3 compared to the cancers localized in the central (CZ) or transitional zones (TZ), the TZ and CZ together constituting the central gland (CG). Recent guidelines for scoring of PCa incorporate different recommendations for cancers localized in the transitional zone or in the peripheral zone 2,4 . Furthermore, recent quantitative studies 5,6 have identified different textural imaging signatures that appear to characterize cancers localized in CG or PZ.

Computer simulations suggest that prostate enlargement due to benign prostatic hyperplasia mechanically impedes prostate cancer growth

“…The resulting algorithms would be of much interest for several applications within the clinical management of PCa on a tissue-scale, patient-specific basis, such as the accurate follow-up of tumor growth during active surveillance or the precise planning of surgery and other treatments (39). Such technology could also help to detect PCa based on the deformation of the prostate boundaries and the internal borders between prostatic regions (44,57). Additionally, it could guide biopsies to better stage and diagnose PCa.…”

Prostate shapes on pre-treatment MRI between prostate cancer patients who do and do not undergo biochemical recurrence are different: Preliminary Findings

“… 5 found statistically significantly lower mean Apparent Diffusion Coefficient (ADC) values within the tumor region for patients with BCR. In one of our recent study 6 statistically significant differences were observed in prostate shape on T2w images between patients with and without prostate cancer.…”

“…Thus, prostate cancer may affect the shape of the prostate capsule as it locally and internally pervades the gland. In 6 , Rusu et al . showed via an atlas based approach that the shape of the prostate capsule and the transition zone as observed on a T2w MRI were significantly different between men with and without prostate cancer.…”

“…showed via an atlas based approach that the shape of the prostate capsule and the transition zone as observed on a T2w MRI were significantly different between men with and without prostate cancer. Building on the findings of 6 , in this work we sought to explore whether an atlas based comparison approach could help identify shape differences in the prostate capsule as observed on pre-treatment T2 weighted MRI between prostate cancer patients who do ( BCR + ) and do not ( BCR − ) have BCR following definitive therapy. Unlike the work showcased in Rusu et al .…”

Novel Quantitative Imaging for Predicting Response to Therapy: Techniques and Clinical Applications

“…77,84,85 Shape features include width, height, depth, perimeter, area, eccentricity, compactness, radial distance, roughness, elongation equivalent diameter, and three-dimensional sphericity of the nodule. 29,51,57 Other features include three-dimensional shape and margin sharpness. 86,87 …”