Biomedical subjects

J Frahm

Publications and source records attributed to J Frahm.

166 records · Page 10Linked to original sources

PubMedDate not supplied

Localized proton NMR spectroscopy of brain tumors using short-echo time STEAM sequences.

Recent progress in localized proton NMR spectroscopy has been utilized to improve the spatial resolution and the metabolic specificity in a study of 19 patients with intracranial tumors. Selected examples demonstrate that short echo time stimulated echo acquisition mode sequences are able (a) to account for macroscopic tissue heterogeneity by reducing the volume of interest to 2-8 ml and (b) to facilitate a reasonable characterization of tumor metabolism by increasing the number of accessible metabolites. Proton NMR spectra were acquired within measuring times of 6.5 min on a 2.0 T whole-body system using the imaging headcoil.

Adult↗

PubMedDate not supplied

Proton NMR spectroscopy of cerebral metabolic alterations in infantile peroxisomal disorders.

Noninvasive studies of cerebral metabolism were performed with use of localized proton MR spectroscopy (MRS) in both healthy controls (n = 4, age 6 weeks to 2 years) and infants (n = 4, age 3-15 months) who had impaired peroxisomal functions classified as variants of Zellweger syndrome. All patients revealed a marked decrease of N-acetylaspartate in white and gray matter, thalamus, and cerebellum, indicating impairment of normal neuronal development as well as neuronal loss. In two cases an increase of cerebral glutamine and a decrease of the cytosolic polyol myo-inositol in gray matter and striatum reflected the impact of a concomitant effect on hepatic function. Two cases 3 and 6 months of age exhibited a notable elevation of mobile lipids and/or cholesterol in white matter. These patients with severe disease died within 4 weeks after the MRS examination. While an increase of free fatty acids generally associated with a lysosomal storage disease was not consistently observed by proton MRS of brain, this technique provides a convenient and safe tool for the direct assessment of neuropathologic aspects of Zellweger syndrome such as neuronal degeneration, demyelination, and consequences of compromised liver function.

Adrenoleukodystrophy↗

PubMedDate not supplied

Signal strength in subsecond FLASH magnetic resonance imaging: the dynamic approach to steady state.

Subsecond fast low-angle shot (FLASH) magnetic resonance imaging (MRI) allows single shot studies of the human heart within measuring times of about 100-300 ms depending on the data matrix. In contrast to conventional FLASH MRI subsecond applications acquire data during the approach to steady state. A detailed analysis of the saturation behavior of the signal is given for the ideal case of a rectangular slice profile. In a second step, realistic slice profiles assuming Gaussian-shaped excitation pulses were taken into account by means of a numerical solution of the Bloch equations. It turns out that the signal strength and the resulting image intensity is considerably higher than may be expected from steady-state considerations. Correspondingly optimized flip angles depend on the number of phase-encoding steps. Assuming long T1 relaxation times as, for example, encountered in muscle and brain tissue and repetition times of 5 ms or less, optimum flip angles are 12 degrees-16 degrees. The use of even higher flip angles (greater than or equal to 20 degrees) causes heavily distorted slice profiles and a dynamic increase of the effective slice thickness. Flip angles of the order of the Ernst angle (6 degrees) correspond to steady-state conditions and lead to considerable signal losses. The theoretical results are confirmed by subsecond FLASH MRI studies of the human heart using a 2.0 T whole-body system (Siemens Magnetom).

Biophysical Phenomena↗

PubMedDate not supplied

The role of the PT in incontinence: innovation and communication to improve patient care.

Physical therapists play a vital role in the management and treatment of incontinence patients, and as a result, a variety of innovations in the field have been made. However, incontinence management is not limited to the PT. Providing the best care to incontinent patients requires open communication among professions, disciplines, and care settings where incontinence specialists may be found. To help illustrate this point, a professional opinion survey was sent to leading PTs and RNs who conservatively treat and manage incontinence. Respondents were asked about the following: entry point, preparation, and practice setting; general practice description; assessment and treatment; individual practice innovations; what is unique to physical therapy and nursing; and interaction between the professions. Twenty-six (26) responses were received. While responses varied among PTs and RNs, both professions agreed that musculoskeletal assessment and treatment were unique contributions of physical therapy while medical/surgical expertise and pharmacologic issues were unique contributions of nursing to the field of incontinence. Although this article focuses in particular on the physical therapist's role in incontinence management, survey results revealed that, overall, knowledge and open communication between the professions is key in the management and treatment of incontinence patients.

Communication↗