Robotically assisted prostate brachytherapy with transrectal ultrasound guidance--Phantom experiments.

PURPOSE: To report the preliminary experimental results obtained with a robot-assisted transrectal ultrasound (TRUS)-guided prostate brachytherapy system. METHODS AND MATERIALS: The system consists of a TRUS unit, a spatially coregistered needle insertion robot, and an FDA-approved treatment planning and image-registered implant system. The robot receives each entry/target coordinate pair of the implant plan, inserts a preloaded needle, and then the seeds are deposited. The needles/sources are tracked in TRUS, thus allowing the plan to be updated as the procedure progresses. RESULTS: The first insertion attempt was recorded for each needle, without adjustment. All clinically relevant locations were reached in a prostate phantom. Nonparallel and parallel needle trajectories were demonstrated. Based on TRUS, the average transverse placement error was 2 mm (worst case 2.5 mm, 80% less than 2 mm), and the average sagittal error was 2.5 mm (worst case 5.0 mm, 70% less than 2.5 mm). CONCLUSIONS: The concept and technical viability of robot-assisted brachytherapy were demonstrated in phantoms. The kinematically decoupled robotic assistant device is inherently safe. Overall performance was promising, but further optimization is necessary to prove the possibility of improved dosimetry.

Dopamine transporter availability in medication free and in bupropion treated depression: a 99mTc-TRODAT-1 SPECT study.

BACKGROUND: Bupropion is thought to exert its antidepressive effect by blocking the dopamine transporter (DAT). The purpose of this study was to evaluate the DAT activity in depressed patients by means of 99mTc-TRODAT-1 SPECT in relation to the efficacy of bupropion treatment. METHODS: In 12 healthy controls and 16 depressed patients the baseline DAT activity was examined. Nine of the 16 patients went through an additional second SPECT investigation, after 4 weeks of bupropion treatment. RESULTS: In the depressed patients, the baseline DAT striatum-occipital ratio (SOR) (1.04+/-.36, mean+/-SD) was not significantly different from that in the control group (1.12+/-.33) (p>.05). Correlation was found between baseline SOR and HAM-D score change (r=-.745, p=.02) of the bupropion treated patients. The average DAT occupancy due to the bupropion treatment was 20.84+/-27.7%. No significant correlation between the therapeutical effectiveness and the occupancy was observed. LIMITATIONS: One of the limiting factors of our study has been the lack of drug monitoring. CONCLUSIONS: In good agreement with other PET studies, we found 20.84% DAT occupancy during bupropion treatment. The lack of correlation between the efficacy of therapy and occupancy of DAT may raise the question as to whether other mechanisms are involved in the effect of bupropion.

System for MR image-guided prostate interventions: canine study.

The purpose of this study was to demonstrate the use of a transrectal system that enables precise magnetic resonance (MR) image guidance and monitoring of prostate interventions. The system used a closed-bore 1.5-T MR imaging unit and enables one to take advantage of the higher signal-to-noise ratio achieved with traditional magnet designs, which is crucial for accurate targeting and monitoring of prostate interventions. In the first of the four canine studies, reliable needle placement, with all needles placed within 2 mm of the desired target site, was achieved. In two other studies, MR imaging was used to monitor distribution of injected contrast agent solution (gadopentetate dimeglumine mixed with trypan blue dye) in and around the prostate, thereby confirming that solution had been delivered to the desired tissue and also detecting faulty injections. In the final study, accurate placement and MR imaging of brachytherapy seeds in the prostate were demonstrated. The described system provides a flexible platform for a variety of minimally invasive MR image-guided therapeutic and diagnostic prostate interventions.

System for robotically assisted prostate biopsy and therapy with intraoperative CT guidance.

RATIONALE AND OBJECTIVES: The purpose of this study was to assess the work-in-progress prototype of an image-guided, robotic system for accurate and consistent placement of transperineal needles into the prostate with intraoperative image guidance inside the gantry of a computed tomographic (CT) scanner. MATERIALS AND METHODS: The coach-mounted system consists of a seven-degrees-of-freedom, passive mounting arm: a remote-center-of-motion robot; and a motorized, radiolucent needle-insertion device to deliver 17-18-gauge implant and biopsy needles into the prostate with the transperineal route. The robot is registered to the image space with a stereotactic adapter. The surgeon plans and controls the intervention in the CT scanner room with a desktop computer that receives DICOM images from the CT scanner. The complete system fits in a carry-on suitcase, does not need calibration, and does not utilize vendor-specific features of the CT scanner. RESULTS: In open air, the average accuracy was better than 1 mm at a 5-8-cm depth. In various phantoms, the average orientation error was 1.3 degrees, and the average distance between the needle tip and the target was 2 mm. CONCLUSION: Results of preliminary experiments indicate that this robotic system may be suitable for transperineal needle placement into the prostate and shows potential in a variety of other percutaneous clinical applications.