PubMed Health⌕ Search

Biomedical subjects

H I Litt

Publications and source records attributed to H I Litt.

6 recordsLinked to original sources
PubMed2001

BaSO4-loaded agarose: a construction material for multimodality imaging phantoms.

RATIONALE AND OBJECTIVES: Phantom studies are an important part of the evaluation of imaging techniques; however, presently available phantom construction materials are not adequate for studies involving both magnetic resonance (MR) imaging and computed tomography (CT). The purpose of this study was to design a phantom construction material useful for multimodality imaging experiments. MATERIALS AND METHODS: Iodinated contrast agent or BaSO4 was added during the formation of agarose gels. Both CT and MR imaging were performed, and T1 and T2 values and CT numbers (in Hounsfield units) were obtained for multiple combinations of contrast material and agarose. Results. The T2 values of agarose gels span the range of those values found in biologic tissues. Phantoms containing iodinated contrast agent were not stable; contrast agent diffused across concentration gradients. BaSO4-loaded agarose phantoms were stable, however, and varying barium concentrations produced phantoms that spanned the range of CT numbers found in biologic tissues. Addition of BaSO4 did not substantially alter T1 or T2 values of agarose gels. Agarose concentration had only a small effect on the CT numbers of BaSO4 suspensions. CONCLUSION: BaSO4-loaded agarose is an effective material for construction of multimodality imaging phantoms. It provides adequate signal intensity for MR imaging and attenuation for CT, with independently variable contrast in both modalities.

Agar↗
PubMed1992

Digital patient records and the medical desktop: an integrated physician workstation for medical informatics training.

The Institute of Medicine and others have advocated a shift from a paper-based to an electronic medical record and many authorities have advanced the concept of a physician workstation that can provide access to a wide variety of both clinically and reference oriented medical information. We have developed a working model of an integrated physician workstation based on a graphically oriented "Medical Desktop," for personal computers. This system gives the user access to much of the information necessary for the practice of medicine, by integrating an electronic medical record (notes, orders, consults, lab values, and radiological studies, organized both independently and in a "Visual Chart") with tools such as drug references, clinical manuals, textbooks of medicine, literature searching, expert system decision support, and electronic communication. It contains an on-line help system that facilitates use and allows access to all the systems' capabilities. This system has been used to teach students and physicians the methods and potential of computer-based medical information management to prepare them for the impact of computers in their practices and educate them concerning the imperative for the involvement of all health care providers in implementing these changes.

Computer Graphics↗
PubMed1989

NMR characteristics of "visible" intracellular myocardial potassium in perfused rat hearts.

Nuclear magnetic resonance (NMR) spectroscopy provides a unique view of ions through its noninvasive character and relaxation time measurements. Several previous studies have demonstrated that only approximately 20% of cardiac intracellular potassium is visible with current NMR techniques. This study investigates the NMR visible intracellular potassium in a perfused rat heart preparation. When shift reagents were used to separate the intra- and extracellular signals, an intracellular T1 of 11.8 +/- 0.6 ms, and an intracellular T2 with two time constants of 1.3 +/- 0.6 ms (33 +/- 8%) and 10.1 +/- 1.9 ms (67 +/- 4%) were measured. Curve stripping techniques used to separate the intra- and extracellular components of a bulk relaxation decay yielded an intracellular T1 of 8.4 +/- 0.3 ms and an intracellular T2 with two time constants of 1.1 +/- 0.6 ms (38 +/- 10%) and 8.0 +/- 1.6 ms (62 +/- 12%). These results demonstrate that there are at least two distinct pools of potassium within the cardiac cell in slow exchange with each other on the NMR time scale. Studies with an enriched 41K perfusate demonstrated that the exchange rate for the visible intra- and extracellular potassium is on the order of 15 min.

Animals↗