This purpose of this study is designed to compare two types of images; magnetic resonance imaging (MRI) and Trans-Rectal Ultrasound (TRUS) to see which one performs more accurately for the image-guided insertion of Fiducial Markers(FMs) within the tumour. Though effective for guiding FM placement at the poles of the prostate gland due to excellent visualization of the prostatic boundaries, TRUS may not be ideally suited for marking the GTV. Conventional TRUS is neither sufficiently sensitive nor specific for accurate visualization of intra-prostatic tumor. A new interventional MRI technique enables needle guidance to the gross tumour Volume (GTV) for FM placement. It is of particular importance that both techniques be evaluated to enable which one is more effective so that it can be implemented in the designs of future trials involving dose-escalation to prostate.
The success of dose escalation strategies in prostate cancer over the last decade has relied on high accuracy in target delineation, localization and radiation delivery. Improved biochemical control with acceptable levels of toxicity (specifically rectal) has been achieved by stringently monitoring the location of the prostate during the course of radiation treatment. Studies in the early 1990's demonstrated that daily bony alignment was a poor surrogate for prostate gland location. Since then, various strategies have been devised to localize the prostate precisely during treatment. Of these, Transrectal Ultrasound (TRUS)-guided gold fiducial marker (FM) insertion and x-ray imaging of markers has been a broadly successful approach. TRUS guidance has been used for fiducial marker insertion within the prostate since 1985 in various centers throughout the world and has also been a standard practice in PMH since 1997 in men undergoing radical external beam radiotherapy. A retrospective comparative study of 106 patients evaluating the relative accuracy of endorectal MRI and TRUS in detecting the location of tumor reported an improved performance of endorectal MRI especially in the base and midgland regions. Over the last few years, mounting experience in the interpretation of prostate MRI, and addition of physiologic imaging sequences has further improved the performance of MRI in detecting and localizing the GTV.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
17
Both are imaging probe devices that is inserted under local anesthetic, in the rectum using lubricant, positioning against the prostate gland, and attached to the table. This is done at baseline (Day 0) under local anesthetic with the patient in partial dorsal lithotomy position
Patient is given local anesthetic transrectally to the prostate base and the probe is inserted with patient in the lateral decubitus position.
University Health Network
Toronto, Ontario, Canada
To compare the performance of MRI and TRUS images in guiding the insertion of a fiducial marker within the Gross Target Volume (GTV)
Time frame: 5 years
To measure the needle targeting accuracy of the MRI-guided technique.
Time frame: 5 years
To validate the accuracy of identifying the GTV on MRI.
Time frame: 5 years
To evaluate MRI methods for the characterization of tissue oxygenation.
Time frame: 5 years
To evaluate the effect of neoadjuvant hormone therapy on tissue oxygenation.
Time frame: 5 years
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