A clinic-based technique of targeted biopsy using magnetic resonance imaging (MRI) and ultrasound may improve the diagnosis and management of prostate cancer, researchers have found.
Although the technology exists to biopsy prostate tumors under MRI guidance, and this has been shown to improve prostate cancer diagnosis, such procedures are time-consuming, costly, and impractical in most settings, according to the first author of the new study, Geoffrey A. Sonn, MD, of the Institute of Urologic Oncology at the University of California, Los Angeles.
However, “Magnetic resonance ultrasound [MR-US] systems that fuse stored MR images with real-time ultrasound combine the resolution of MRI with the ease and practicality of ultrasound, offering a savings in time and cost, while potentially retaining the accuracy of MR-guided biopsy,” explained Sonn in a statement issued by Elsevier Health Sciences. The study appears in the Elsevier publication The Journal of Urology (2012;189:86-92).
Sonn and his fellow investigators evaluated prostate cancer detection rates in 171 consecutive men (median age 65 years) using MR-US fusion prostate biopsy. Most of the men (106) underwent targeted biopsy for active surveillance; the remaining 65 men who had the procedure had persistently increased prostate-specific antigen (PSA) but negative prior conventional biopsy. All participants had a median PSA of 4.9 ng/mL and a median prostate size of 48 cc.
The patients underwent MRI for visualization of the prostate and any lesions. The information was then fed into a device that fuses the MRI images with real-time, three-dimensional ultrasound to allow the urologist to view the lesion during the biopsy. MR-US fusion biopsy takes about 20 minutes, with the patient under local anesthesia.
Prostate cancer was found in 53% of the men, with 38% of the men having cancer with a Gleason grade of at least 7. The targeted biopsy method was three times more likely to identify cancer than was a systematic biopsy (21% vs 7%). Of the men with Gleason 7 or greater cancer, 38% had disease detected only on targeted biopsies.
The targeted biopsy findings correlated with level of suspicion on MRI. Of 16 men, 15 (94%) with an image grade 5 target (highest suspicion) had prostate cancer, including 7 with cancer of Gleason 7 or greater.
Sonn and colleagues concluded that prostate lesions identified on MRI can be accurately targeted using MR-US fusion biopsy by a urologist in a clinic, and that biopsy findings correlate with level of suspicion on MRI.