Using MRI to Diagnose and Treat Prostate Cancers
By Jerry Berger
Beth Israel Deaconess Medical Center Staff
Beth Israel Deaconess Medical Center is combining the latest in magnetic resonance imaging (MRI) technology with state of the art computer software to more accurately diagnose and treat prostate cancers.
The capabilities are derived from the combination of the latest MRI hardware and software. On the hardware side, a General Electric high field strength MRI unit operating at 3T (T for Tesla, or a unit of measuring magnetic strength) and the use of a specialized coil, by Medrad, Inc., allow better detection of the MRI signal that enables high spatial resolution imaging of the prostate gland.
This capacity has been combined with a software analysis tool developed by Israel's Weizmann Institute that yields color-coded images that display benign images in green - and cancerous lesions in red.
To date, a prostate cancer diagnosis has been made by taking data from biopsies, digital exams and blood tests and combining them into a table that predicts the probability that a patient has cancer. While MRI has been somewhat useful in trying to pinpoint the location and extent of tumors within the prostate, the technology was not sophisticated enough to reliably map small, early stage lesions.
The BIDMC technique combines high resolution imaging with dynamic contrast-enhanced information as well as diffusion-weighted imaging - effectively "looking" at the gland in multiple ways, to provide a multiparametric method of localizing and staging prostate cancers.
"This method of imaging the prostate allows us to view the gland in great detail in order to improve the accuracy of staging of prostate cancers, or to help localize tumors that are suspected clinically but have not been localized and diagnosed with biopsy," says
Maryellen Sun, MD, a radiologist at BIDMC. "It can be invaluable in guiding the choice of a treatment plan that is tailored for the patient."
Dynamic contrast enhancement is a method of imaging that allows the nature of a tumor to be determined through repeated sampling of images during the administration of contrast material, a 'dye' injected into a patient's vein. If spatial resolution is not high enough on these images, small tumors could elude detection, since tumors smaller than the "slice" made by the MRI may be missed. The 3T MRI enables "slices" two millimeters in size rather than the five to seven millimeters common from older versions. The 3TP software uses an analysis that allows for longer time sampling, thus enabling the pursuit of high spatial resolution.
After the images are taken, radiologists turn to the 3TP software developed by Hadassa Degani, PhD, at the Weizmann Institute. Her formula measures tissue characteristics at multiple distinct time points and assigns a color to each pixel of the image, so that malignancies appear in red.
Armed with this information, urological surgeons or radiation oncologists are able to create a personalized treatment plan that might include either surgery to remove the cancer with the least amount of damage to surrounding tissue or nerves, or brachytherapy - the implantation of radioactive "seeds" - to better focus radiation dose.
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.
Posted October 2011