PCMRI - an MRI/TRUS System for the Evaluation of the Prostate

Prostate cancer (PC) is the most common male malignancy in the western world. In the U.S. there are approximately 230,000 new diagnoses annually. Each year, 40,000 men with established disease die from PC.

Early detection is possible using prostate specific antigen (PSA) and/or DRE, followed by biopsy if PC is suspected. Biopsy is generally carried out under transrectal ultrasound (TRUS) guidance through the rectum wall. Typically, 6-13 samples from different areas of the prostate are taken in order to cover the entire gland area. Since TRUS cannot accurately detect PC, prostate biopsies, to date, are in fact random biopsies. Furthermore, PSA may be elevated, in patients without PC, leading to as many as 75% of patients undergoing unnecessary TRUS guided biopsy [1,2].

The need for accurate preoperative evaluation of PC, as well as early detection of the tumor has lead to numerous applications of Magnetic Resonance Imaging (MRI) of the prostate.1 The sensitivity and specificity of whole body MRI with pelvic phased-array coils is as low as ~70%. Improved sensitivity is obtained using an endorectal coil where efficacies of ~85% are reported due to the improved signal to noise ratio (SNR) of such coils.2

One of the major limitations of conventional MRI scanners is their cost and limited availability. A portable, hand-held MR scanner capable of detecting PC is thus, of interest. TopSpin has developed a novel MRI based system for prostate imaging in Urology. The primary use of the prostate MRI probe will be diagnosis, staging and guidance of minimally invasive therapy for PC.

The system consists of a miniaturized transrectal MRI probe, incorporating all magnetic field sources and coils. The MRI probe is integrated with and used in conjunction with a TRUS system. The TRUS probe provides prostate gross anatomy and allows the Urologist to select the cross-section(s) of interest within the prostate. The MRI probe provides MRI images of the selected cross-section(s) with improved tissue characterization that enable localizing tumors within the prostate. Fusion of both images has promise of significantly improving the ability to direct biopsies to regions of a much higher likelihood for being malignant. In addition, the system is capable of guiding local treatment such as Cryotherapy or Brachytherapy.