IN VIVO ASSESSMENT OF CANINE PROSTATE THERMAL ABLATIONS WITH MTI

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The most common malignancy in men in the United States, prostate cancer affects over 234,000 men each year [1]. High intensity ultrasound is a potential minimally invasive treatment capable of treating it. With MR guidance, this treatment option has the potential to locally ablate prostate tissue while preserving sensitive tissues like the urethra or rectal wall. However, while temperatures can be monitored under MR guidance, using such techniques as PRF imaging, and tissue perfusion can be assessed with contrast-enhanced imaging, the best methods of directly imaging the prostate tissue changes resulting from ablation are less clear. It has previously been noted that there is also a strong magnetization transfer (MT) effect in prostate tissue [2], and the purpose of this work was to investigate whether MT imaging could provide additional information concerning tissue changes in the prostate in high intensity ultrasound lesions in vivo. Methods Three imaging experiments were performed with two in vivo canine prostates on a 0.5T Signa SP scanner (General Electric, Milwaukee, WI). Two lesions were created in both animals with high intensity interstitial ultrasound applicators (10 mm x 180¿ directional pattern) [3] inserted from the ventral surface. The prostate glands were imaged immediately after treatment, and one of these dogs was imaged again four days later and then sacrificed. On-resonance magnetization transfer imaging was performed with a 3D SPGR pulse sequence, alternating the MT pulse on and off from scan to scan. The on resonance pulses were 1-2-1 binomial pulses. Magnetization ratio images were created using MATLAB (The Mathworks, Natick, MA) using equation 1 and scaled to between zero and one. Also, Gadolinium contrast enhanced images were acquired through the created lesions for comparison.