Learn More
A new application of magnetic resonance (MR) imaging to map the spatial and temporal distribution of the effects of Nd:YAG lasers on tissues was studied. The temperature dependence of MR relaxation mechanisms and the high sensitivity of MR to changes in the mobility and distribution of tissue water make it particularly suitable for the demonstration and(More)
A treatment planning system to compute intensity modulated radiotherapy (IMRT) treatments using inverse planning was investigated. The system was designed to optimize the intensity patterns required to treat a specified target volume with specified normal structure constraints. A beam model that uses the convolution of pencil beams was used to compute the(More)
This paper discusses the application of statistical pattern recognition techniques to problems in diagnostic ultrasound. Using our own system as an example, we describe the concepts and specific methods that we have applied to a problem involving the computer-aided classification of breast tissue in vivo. Topics include feature generation, feature selection(More)
We applied diffusion-sensitive echo planar (Instascan) imaging to study thermal changes caused by a Nd:YAG laser. Images of phantom materials and normal rabbit brain tissue in vivo, acquired in 150 ms, every 2s, clearly showed the dynamics of temperature-related signal intensity changes in the regions irradiated by the laser.
We have used MR monitoring to guide and evaluate the effects of the Nd:YAG interstitial laser on a well-characterized rat brain tumor model (C6). MRI was used to determine the tumor size, verify the location of the interstitial probe, and evaluate the size and location of the laser-induced lesion during and after treatment. During laser irradiation, an(More)
RATIONALE AND OBJECTIVES Laser irradiation therapy in deep tissues requires a monitoring method other than visual guidance. Magnetic resonance imaging (MRI) can be used for this purpose because it visualizes soft tissue structures and heat distribution. METHODS The authors performed interstitial laser irradiations in rat livers with various laser outputs(More)
Two-dimensional Fourier transform Carr-Purcell-Meiboom-Gill (CPMG) imaging sequences were implemented on 1.9-T and 1.5-T imaging systems in order to test their ability to characterize in vivo transverse decay curves (TDCs). Both hard- and soft-pulse CPMG imaging sequences, consisting of up to 128 echoes with echo spacings of approximately 10 ms were(More)
Proton T2 relaxation and its biexponential components have been determined in rabbit skeletal muscle in the presence and absence of GdDTPA. The effect of GdDTPA, which distributes only in the extracellular space, was greatest in the longer-relaxing T2 component (T22). A 27% reduction in T22 was measured for slow-twitch (red) muscle and 17% for fast-twitch(More)
Magnetic resonance imaging techniques can be used to control and monitor the deposition of destructive energy. The authors evaluated the feasibility of phosphorus-31 magnetic resonance spectroscopy for the control, monitoring, and prediction of the three-dimensional extent of tissue destruction during interstitial laser surgery. Characteristic metabolic(More)