Comparison Between Micro-Ultrasound and Multiparametric MRI Regarding the Correct Identification of Prostate Cancer Lesions

Abstract

Introduction: Multiparametric MRI (mpMRI) has become the standard imaging technique for the diagnosis of prostate cancer. However, mpMRI pathways are depending on experience, expertise, and information transfer from radiology to urology. Micro-ultrasound (Micro-US) is a new system, using high frequency (up to 29 MHz) and high resolution (down to 75 µm) ultrasound images. We evaluated the diagnostic performance of Micro-US in the detection of the prostate cancer index lesion and compared its performance to mpMRI using pathological whole mount sections as the reference.

Materials and methods: We retrospectively reviewed the data of 32 patients with diagnosis of prostate cancer and scheduled for radical prostatectomy and who underwent Micro-US before surgery. Still images and cineloops of Micro-US were recorded. Sixteen patients had also mpMRI images with acceptable quality and complete sequences available. For validation purposes each prostate was partitioned into 12 sectors for a total of 192 sectors evaluated. Micro-US and mpMRI images were both scored according to a validated system (PRI-MUS and Pi-RADS) where a score ≥3 was suspicious for both scores. Preoperative and postoperative results regarding the identification of the index lesion, the biggest lesion visible, were then compared and sensitivity, specificity, negative and positive predictive values, and accuracy were calculated.

Results: Median age was 67 years, median PSA was 6.2ng/ml, and median cancer volume of the index lesion was 3.1cc. The sensitivity of Micro-US in the index lesion detection was 76.5%, specificity 76.6%, negative predictive value 85.6%, positive predictive value 64.1% and 76.6% of accuracy. The sensitivity of mpMRI was 65.1%, specificity 93.4%, negative predictive value 83.2%, positive predictive value 84.3%, and 81.8% of accuracy (all p> .05).

Conclusion: Micro-US showed good reliability in identifying prostate cancer index lesions. Its performance is comparable to that of mpMRI.

Keywords: Diagnosis; Micro-ultrasound; Multiparametric magnetic resonance imaging; Prostate biopsy; Prostate cancer.