MRI fused with ultrasound to strengthen prostate cancer diagnosis

By Sally Robertson, B.Sc.Dec 24 2012

Researchers have developed a technique that fuses magnetic resonance imaging (MRI) with ultrasound to improve the detection and treatment of prostate cancer.

Evaluation of the office-based magnetic resonance ultrasound fusion biopsy system, called Artemis, showed that the system was better at detecting prostate cancer than ultrasound-guided systematic biopsy alone, in 171 men who underwent the procedure for active surveillance or increased prostate-specific antigen despite a previous negative conventional biopsy.

"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 savings in time and cost, while potentially retaining the accuracy of MR-guided biopsy," write Leonard Marks (Institute of Urologic Oncology, California, USA) and team in the Journal of Urology.

The researchers report that the MR-US targeted biopsy was three times more likely to reveal the presence of prostate cancer than a systematic biopsy, with cancer detected in 21% of 486 targeted cores compared with 7% of 1741 cores systematically taken by ultrasound.

Overall, prostate cancer was identified in 60 (53%) of the men, of whom 34 (38%) had a Gleason grade of 7 or greater. Among those with Gleason grade 7 or higher, 38% had cancer detected by targeted biopsy only.

Furthermore, the degree of cancer suspicion on MRI correlated with cancer diagnosis overall and with diagnosis of cancer graded Gleason 7 or higher. The level of suspicion was assessed using a 5-point semiquantitative scoring system that allowed for graded levels of suspicion, as opposed to other protocols in which a binary score of normal or abnormal is assigned, explain Marks et al.

"Thus, the present scoring system follows the guidelines recently released by the European Society of Uroradiology," they say.

"Targeted biopsy may improve patient selection, making surveillance a more attractive option to patients while reducing progression to active treatment," say the researchers.

"Furthermore, the tracking feature of the Artemis device allows the urologist to return to the exact area of prior positive biopsies, enabling the physician to follow individual tumors over time."

Further work, including a detailed study correlating MRI, targeted biopsy results and prostatectomy specimens, is ongoing, they say.

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