The shapes of the prostate and one of its compartments, called the transitional zone, are different in men with prostate cancer than in men without the disease, research shows.
The finding may offer a new strategy for diagnosing prostate cancer, and predicting how aggressive it is.
The study, “Computational imaging reveals shape differences between normal and malignant prostates on MRI,” was published in the journal Scientific Reports.
“Looking at shape is a fundamental shift from looking at the intensity of pixels in an image to predict if a patient has prostate cancer,” Anant Madabhushi, F. Alex Nason Professor of Biomedical Engineering at Case Western Reserve University and leader of the research, said in a news release. “Pixel intensities vary, but shape is resilient.
“Here, we potentially have an image-based biomarker for prostate cancer, which is not greatly sensitive to the MRI parameters used by each institution, the maker of the MRI or the scanner itself,” Madabhushi added.
Multi-parametric magnetic resonance imaging (MRI) plays an essential role in managing prostate cancer, helping doctors try to keep it localized. In addition to providing structural and functional images of the prostate, MRI reveals differences in cancers based on their location in the prostate’s anatomic subregions.
Madabhushi and colleagues at Case Western Reserve decided to try to characterize differences in the shape of the prostate and the central gland — a combination of the prostate’s central and transitional zones — between men with biopsy-confirmed prostate cancer and men without the disease.
They analyzed the MRI scans of 70 prostates from five medical institutions. Thirty-five of the men had prostate cancer, 24 had no prostate or other kind of cancer, and 11 men had rectal cancer but no clinical or MRI evidence of prostate cancer.
To check differences in prostate shapes, the researchers aligned images from the 35 prostates with cancer into a single frame, creating a statistical shape atlas. They created a second atlas with images of the 35 healthy prostates.
After controlling for size, the atlas comparisons between cancerous and non-cancerous prostates revealed differences in the gland itself and the shape of the transitional zone.
The team then compared prostate images from each of the five medical institutions. They discovered that the differences in shapes they had observed between cancerous and non-cancerous prostates were consistent no matter which institution the images came from.
If shape proves to be a reliable marker of prostate cancer, it could be combined with radiomics to help diagnose the disease, Madabhushi said. Radiomics uses computer algorithms to extract distinguishing characteristics of cancerous and non-cancerous tissues.
Madabhushi and his colleagues recently published a study in the Journal of Magnetic Resonance Imaging demonstrating that cancer can be accurately identified by differences in tumors in the prostate’s peripheral zone, and the tumors’ microarchitecture.
The team is now working on identifying radiomic features from the peripheral and transitional zones of the prostate, along with measurements derived from the prostate’s shape. The goal is to see whether they can predict the cancer’s presence. They also want to determine if shape can predict a cancer’s aggressiveness—information critical to doctors’ decisions about how to treat patients.