Real-time MRI/US fusion-guided biopsy improves detection rates of prostate cancer in pre-biopsied patients

Abstract

According to the guidelines of the European Association of Urology (EAU) on prostate cancer (PCa) in 2013, patients with increasing prostate-specific antigen (PSA) levels, suspicious digital rectal examination (DRE) or high-grade prostatic intraepithelial neoplasia after negative prostate biopsy (PB) should undergo a repeat biopsy. Low cancer detection rates in the repeat biopsy illuminate the dilemma of the international gold standard of transrectal ultrasound (TRUS) guided PB in the detection of PCa. Our study evaluated the combination of TRUS and prostate magnetic resonance imaging (MRI) and its reported high sensitivities and high specificities by using real-time MRI/US fusion-guided biopsy. The detection of clinically significant PCa was investigated. 128 consecutive patients in the period of January 2012 to August 2013 were included. All patients had at least one TRUS-guided biopsy with negative findings and the clinical indication for a systematic re-biopsy. Prior to the MRI/US fusion all patients underwent a 3 Tesla prostate MRI without endorectal coil. The MRI data were uploaded to a modern US system. The B-mode, power-mode, elastography and CEUS imaging were used to classify the suspicious lesions from the MRI on a scale of 0-3 and a US sum score was calculated. The lesion was consecutively biopsied by real-time MRI/US fusion followed by a systematic 10 core biopsy. Among 128 patients 51 PCa could be detected (39.8%). From these 51 PCa cases, clinically significant PCa was detected by MRI/US fusion-guided biopsy as follows: Gleason score >7 in 9 of 10 patients; Gleason score=7 in 14 of 20 patients and Gleason score <7 in 13 of 21 patients. A positive correlation was shown between the US sum score and the associated PI-RADS score in 65 patients in whom lesions were classified by PI-RADS. A positive correlation was further shown between the US sum score and the Gleason score of all suspicious and biopsied lesions. MRI/US fusion and TRUS-guided biopsy combined, detected 30 of 51 PCa; 6 of 51 PCa were detected by MRI/US fusion alone and 15 of 51 PCa by conventional TRUS-guided biopsy alone. Real-time MR/US fusion increases detection rates of PCa in patients undergoing repeat biopsy. Especially, clinically significant PCa with a Gleason score ≥ 7 were almost exclusively detected by MR/US fusion-guided biopsy.