PubMed Health⌕ Search

Biomedical subjects

Peter C Johnson

Publications and source records attributed to Peter C Johnson.

3 recordsLinked to original sources
PubMed2006

Cardiac imaging using multislice computed tomography scanners: technical considerations.

Conventional coronary angiography is currently the gold standard in the detection and diagnosis of coronary artery disease. This modality, however, is invasive in nature. Hence, there is a need for noninvasive imaging techniques to provide comprehensive assessment of coronary artery disease, especially in stable patients at low to moderate risk of disease. In recent years, a number of noninvasive modalities have found wide applications in cardiac imaging. Most recent investigations have used magnetic resonance imaging, multislice computed tomography and electron-beam computed tomography scanners. This review discusses the clinical challenges existing in the field of cardiac imaging and focuses on the technical advancements of multislice computed tomography scanners that have made them a very attractive noninvasive option for the detection and diagnosis of coronary artery disease.

Atherosclerosis↗
PubMed2002

Thermal model for fast simulation during magnetic resonance imaging guidance of radio frequency tumor ablation.

Thermal ablation of a tumor with radio frequency (rf) energy from a small probe inserted into the solid tumor can be accomplished with minimal invasiveness under guidance with magnetic resonance imaging (MRI). A theoretical study is presented of 3D temperature distribution dynamics in tissue with rf heating to show the feasibility of fast numerical solution for repeated simulations during an ablation procedure. Model simulations are intended to be used during an ablation treatment together with temperature field images obtained by MR to predict the effect of alternative strategies of source heating and placement. A feature of the model is that it incorporates a heat source term that varies with distance from the rf probe to avoid the need for solving electric field equations. The effects of perfusion and internal cooling of the rf probe on the temperature distribution are simulated to show the model flexibility. Using a personal computer (PC), numerical solution of the model equations required 10 s to 2 min depending on the perfusion-temperature relationship. The results show the feasibility of using thermal model simulations in an iterative manner with MR images to help guide thermal ablation procedures in the clinical setting.

Biomedical Engineering↗