There are currently limitations associated with the prostate biopsy procedure, which is the most commonly used method for a definitive diagnosis of prostate cancer. With the use of two-dimensional (2D) transrectal ultrasound (TRUS) for needle-guidance in this procedure, the physician has restricted anatomical reference points for guiding the needle to target sites. Further, any motion of the physician's hand during the procedure may cause the prostate to move or deform to a prohibitive extent. These variations make it difficult to establish a consistent reference frame for guiding a needle. We have developed a 3D navigation system for prostate biopsy, which addresses these shortcomings. This system is composed of a 3D US imaging subsystem and a passive mechanical arm to minimize prostate motion. To validate our prototype, a series of experiments were performed on prostate phantoms. The 3D scan of the string phantom produced minimal geometric distortions, and the geometric error of the 3D imaging subsystem was 0.37 mm. The accuracy of 3D prostate segmentation was determined by comparing the known volume in a certified phantom to a reconstructed volume generated by our system and was shown to estimate the volume with less then 5% error. Biopsy needle guidance accuracy tests in agar prostate phantoms showed that the mean error was 2.1 mm and the 3D location of the biopsy core was recorded with a mean error of 1.8 mm. In this paper, we describe the mechanical design and validation of the prototype system using an in vitro prostate phantom. Preliminary results from an ongoing clinical trial show that prostate motion is small with an in-plane displacement of less than 1 mm during the biopsy procedure.

Our results compare favorably with a clinical need for a TRE of less than 2.5 mm, and suggest that image-based registration is superior to surface-based registration for 3D TRUS-guided prostate biopsies, since it does not require segmentation.

MRI-targeted TRUS-guided prostate biopsy using cognitive registration appears to be inferior to MRI-TRUS fusion, with fewer than 50% of clinically significant PCA lesions successfully sampled. No statistically significant difference in biopsy accuracy was seen according to operator experience with prostate MRI or MRI-TRUS fusion.

Biopsy of the prostate using ultrasound guidance is the clinical gold standard for diagnosis of prostate adenocarcinoma. The current prostate biopsy procedure is limited to using 2D transrectal ultrasound (TRUS) images to target biopsy sites and record biopsy core locations for postbiopsy confirmation. Localization of the 2D image in its actual 3D position is ambiguous and limits procedural accuracy and reproducibility. We have developed a 3D TRUS prostate biopsy system that provides 3D intrabiopsy information for needle guidance and biopsy location recording. The system conforms to the workflow and imaging technology of the current biopsy procedure, making it easier for clinical integration. In this paper, we describe the system design and validate the system accuracy by performing mock biopsies on US/CT multimodal patient-specific prostate phantoms. Our biopsy system generated 3D patient-specific models of the prostate with volume errors less than 3.5% and mean boundary errors of less than 1 mm. Using the 3D biopsy system, needles were guided to within 2.3 +/- 1.0 mm of 3D targets and with a high probability of biopsying clinically significant tumors. The positions of the actual biopsy sites were accurately localized to within 1.5 +/- 0.8 mm.

Registration to compensate for prostate motion during 3D TRUS-guided biopsy can be performed with a measured accuracy of less than 2 mm and a speed of 1.1 s, which is an important step toward improving the targeting accuracy of a 3D TRUS-guided biopsy system.