Laser-induced thermotherapy of the vertebral body: preliminary assessment of safety and real-time magnetic resonance monitoring in an animal model.
OBJECTIVE
To evaluate the safety of percutaneous laser-induced thermotherapy (LITT) of vertebral bodies and the feasibility of monitoring the thermal effects with real-time magnetic resonance (MR) imaging.


METHODS
Laser fibers were placed in nine vertebral bodies of two minipigs under CT-guidance. LITT was performed in an open 0.5 T MR scanner using an Nd: YAG laser source. A T1-weighted MR sequence was used for continuous color-coded temperature monitoring. Histology of the vertebral body and spinal cord were subsequently obtained.


RESULTS
Thermal lesions of the vertebral bodies measured 8 to 11 mm (mean 9.3 mm) in diameter. Thermal injuries of the spinal cord were observed in all four levels in which cortical bone surrounding the spinal canal was damaged during needle placement and in none with intact cortical bone. MR monitoring of the thermal effect was possible only if acquired in breath-hold technique.


CONCLUSIONS
An intact cortical bone seems to be a prerequisite for safe LITT of the vertebral body. Real-time MR-monitoring of the thermal effect in vertebral bodies and the spinal canal was feasible with breath-hold acquisition. Larger studies are necessary to further evaluate accuracy of real-time MR imaging.
D000818:Animals; D002056:Burns / Q000209:etiology / Q000473:pathology; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000379:methods*; D007834:Lasers; D008279:Magnetic Resonance Imaging / Q000379:methods*; D023421:Models, Animal; D008991:Monitoring, Physiologic; D013115:Spinal Canal / Q000473:pathology*; D013556:Swine, Miniature