Dynamic T1-weighted magnetic resonance imaging of interstitial laser photocoagulation in the liver: observations on in vivo temperature sensitivity.
OBJECTIVE
Magnetic resonance imaging's (MRI) potential to monitor interstitial laser photocoagulation (ILP) has been previously demonstrated and is further tested here with improved spatial and temporal resolution.


METHODS
In vivo experiments employed fiber-delivered 1,064 nm light (3.0 W, 150 sec) in six rabbit livers monitored under T1-weighted FSE MRI as 1 image/10 sec and a 3 mm thick 8 cm FOV. Image signal intensities (SI) were compared with temperatures (T) at 7, 10, and 15 mm from the fiber.


RESULTS
Data showed 33 degrees C < T < 60 degrees C. SI did not vary inverselinearly with T; changes in the tissue altered the MRI signal interfering with the SI changes due to temperature.


CONCLUSIONS
MRI cannot map SI-derived temperatures over the entire treatment site. The role of MRI's temperature sensitivity must be coordinated with organ- and dose-specific tissue changes.
Fried
M P
MP
Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, USA.
Morrison
P R
PR
Hushek
S G
SG
Kernahan
G A
GA
Jolesz
F A
FA
D000818:Animals; D006358:Hot Temperature; D017075:Laser Coagulation; D008099:Liver / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods; D011817:Rabbits