Cutting Edge Urology

T his PDF belongs to matthew.hooson@springer.co ULTRASOUND MRI FUSION BIOPSY IN PROSTATE GLAND • 35  represented by the detection of suspicious lesions on MRI. Then the urologist performs a standard US-guided biopsy, either by a transrectal or a transperineal approach, trying to direct the needles toward the areas suspicious on mp-MRI. Many authors suggest better efficiency and accuracy compared to standard biopsy [16, 17]. The most important disadvantage relates to the learning curve and reproducibility of this strategy. This approach requires an experienced urologist to translate the information of the mp-MRI onto real-time US, which can be challenging according to the deformation and the anatomical characteristics of the prostate. Finally, MRI/US fusion software-based targeted biopsies represent a novel approach devel- oped to improve the accuracy of prostate biopsy, allow dissemination of the technique, and permit the storage of images for future resampling. MRI/US fusi n software-based targeted biopsy devices allow to align the pre-biopsy MR images with intraoperative TRUS in order to enable the urologist to perform targeted biopsy directed toward MR-visible lesions. This approach combines the high diagnostic accuracy of MRI for detecting PCa with TRUS, which represents a procedure well mas- tered by urologists. The process of coregistration of MRI and US images is automatized by the use of a fusion device, and therefore the results are likely to be more consistent across different centers. Coregistrat ion of MRI and US Im ages MRI to US cogn itive fusion is complicated by the significant deformation of the prostate shape that occurs between TR US and MRI (with or without an endorectal coil). The software-based registration method corrects this effect to achieve better diagnostic accuracy [18]. There are two different methods to register MR images to live TRUS: rigid and elastic regis- tration. Both of them aim to align the MR and US images through the identification of landmarks present on both corresponding images. The outer shape of the prostate is used to match the MRI contour to the live US image. Fig. 2: In-bore biopsy. ( a ) Needle-in control scans are performed in two different planes (axial and coronal); ( b ) targeted cores are taken from each lesion using an MRI-compatible, 18G, fully automatic biopsy gun. Cutting EDGE_Urology(SUN)_final.indd 35 27-Mar-18 10:00:30 AM