Magnetic resonance guided, focal laser induced interstitial thermal therapy in a canine prostate model.
OBJECTIVE
We evaluated a newly Food and Drug Administration cleared, closed loop, magnetic resonance guided laser induced interstitial thermal therapy system for targeted ablation of prostate tissue to assess the feasibility of targeting, real-time monitoring and predicting lesion generation in the magnetic resonance environment.


METHODS
Seven mongrel dogs (University of Texas Health Science Center, Houston, Texas) with (2) and without (5) canine transmissible venereal tumors in the prostate were imaged with a 1.5 T magnetic resonance imaging scanner. Real-time 3-dimensional magnetic resonance imaging was used to accurately position water cooled, 980 nm laser applicators to predetermined targets in the canine prostate. Destruction of targeted tissue was guided by real-time magnetic resonance temperature imaging to precisely control thermal ablation. Magnetic resonance predictions of thermal damage were correlated with posttreatment imaging results and compared to histopathology findings.


RESULTS
Template based targeting using magnetic resonance guidance allowed the laser applicator to be placed within a mean ± SD of 1.1 ± 0.7 mm of the target site. Mean width and length of the ablation zone on magnetic resonance imaging were 13.7 ± 1.3 and 19.0 ± 4.2 mm, respectively, using single and compound exposures. The damage predicted by magnetic resonance based thermal damage calculations correlated with the damage on posttreatment imaging with a slope near unity and excellent correlation (r(2) = 0.94).


CONCLUSIONS
This laser induced interstitial thermal therapy system provided rapid, localized tissue heating under magnetic resonance temperature imaging control. Combined with real-time monitoring and template based planning, magnetic resonance guided, laser induced interstitial thermal therapy is an attractive modality for prostate cancer focal therapy.
Stafford
R Jason
RJ
Department of Imaging Physics, University of Texas M D Anderson Cancer Center, Houston, Texas 77030-4009, USA. jstafford@mdanderson.org
Shetty
Anil
A
Elliott
Andrew M
AM
Klumpp
Sherry A
SA
McNichols
Roger J
RJ
Gowda
Ashok
A
Hazle
John D
JD
Ward
John F
JF
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D053685:Laser Therapy / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology / Q000601:surgery*; D025321:Surgery, Computer-Assisted