Proton MR spectroscopy of the brain in AIDS dementia complex.

Proton MR spectroscopy of the brain has been undertaken in 8 healthy volunteers and in 11 patients with human immunodeficiency virus infection and varying stages of AIDS dementia complex (ADC). Spectral appearances in patients with no ADC or early ADC were not significantly different from normal volunteers. Spectra from patients with moderate to severe ADC exhibited significant reductions in levels of N-acetyl aspartate (NAA) relative to creatine (Cr) and also showed elevations in choline containing compounds (relative to Cr).

Ureteric jets: evaluation of normal flow dynamics with color Doppler sonography.

This study was designed to investigate a variety of sonographic features of ureteric jets in order to define patterns of flow and ranges of flow values in an asymptomatic population. The following features of ureteric jets were measured during a period of up to 30 min in a group of 15 asymptomatic volunteers after oral hydration (the mean value was calculated on each side): peak velocity (mean, 57 cm/sec); jet duration (mean, 4.6 sec); and number of peaks and subpeaks (mean, 2.

In vivo and in vitro 31P magnetic resonance spectroscopy of focal hepatic malignancies.

In vivo 31P magnetic resonance spectroscopy (MRS) was undertaken in 28 healthy adult individuals and 32 patients with hepatic malignancies of varying histology, using chemical shift imaging techniques. The mean peak area ratio (total range) of phosphomonoester (PME) to phosphodiester (PDE) in the health adult group was 0.23 (0.

Phosphorus-31 magnetic resonance spectroscopy of the human liver using chemical shift imaging techniques.

Phosphorus-31 magnetic resonance spectroscopy of the human liver was undertaken in 28 healthy adult individuals and in 49 patients with liver disease of varying aetiology. Data localised to the liver were obtained using chemical shift imaging techniques. The mean (+/- 1 S.

Effect of tendon orientation on MR imaging signal intensity: a manifestation of the "magic angle" phenomenon.

To determine whether orientation in the static field may be responsible for the frequent occurrence of increased signal intensity within normal tendons at magnetic resonance (MR) imaging, seven healthy volunteers were imaged by means of a 1.5-T unit and standard clinical pulse sequences. The wrist, ankle, and shoulder regions were evaluated with local coils.

In vivo detection of metabolic changes in a mouse model of scrapie using nuclear magnetic resonance spectroscopy.

In vivo proton nuclear magnetic resonance (NMR) spectroscopy studies of scrapie in a mouse model have shown the appearance of an abnormal peak in the brain early in the incubation period. This abnormal peak was detected weeks before the detection of a protease-resistant form of a membrane protein and vacuolar histopathology in vitro, and several months before clinical signs, and the signal increased in intensity as the disease progressed. In the chronic stage of the disease, a reduction in N-acetyl aspartate levels was observed using in vivo and in vitro proton NMR spectroscopy.

Red blood cell magnesium and chronic fatigue syndrome.

The hypotheses that patients with chronic fatigue syndrome (CFS) have low red blood cell magnesium and that magnesium treatment would improve the wellbeing of such patients were tested in a case-control study and a randomised, double-blind, placebo-controlled trial, respectively. In the case-control study, 20 patients with CFS had lower red cell magnesium concentrations than did 20 healthy control subjects matched for age, sex, and social class (difference 0.1 mmol/l, 95% confidence interval [CI] 0.

Saturation effects in phosphorus-31 magnetic resonance spectra of the human liver.

Phosphorus-31 liver spectra were recorded from 6 controls and 12 patients with liver disease using TR values of 0.5 and 5 s and a pulse angle of 45 degrees. One of the control subjects was also examined at seven TR values ranging from 0.

Proton MR spectroscopy of the brain in infants.

Proton magnetic resonance spectroscopy (MRS) was used to study the brain of 2 normal and 15 abnormal infants aged from 33 weeks postmenstrual age (PMA) to 14 months postnatal age. Eleven of the infants were examined on at least two occasions. The principal clinical diagnoses in the abnormal infants were perinatal ischemic and hemorrhagic brain injury.

Effects of sighting and sensory dominance on monovision high and low contrast visual acuity.

We investigated the relationship between ocular dominance and monovision visual performance in 15 presbyopic subjects. Ocular dominance was determined using sighting (hole-in-the-card and mirror tests) and sensory (anisometropic blur suppression test) methods. Correcting the dominant sighting eye for a given viewing distance was found to be an unreliable method of optimizing blur suppression or binocular high/low contrast visual acuity at that distance.

Soft contact lens-induced longitudinal spherical aberration and its effect on contrast sensitivity.

Some investigators have suggested that the poor quality of vision which some spherical, single vision, soft lens-wearing patients report may be a result of spherical aberration induced in the ocular system when a soft lens is placed on the eye. In this study, the longitudinal spherical aberration of spherical soft lenses, both on and off the eye, was calculated using an aspheric corneal model and two-dimensional ray tracing program. Specifically designed front-surface aspheric, soft lenses were produced which demonstrated levels of in-air power variation similar to that calculated for similar-parameter spherically surface lenses.

Proton MR spectroscopy of intracranial tumours: in vivo and in vitro studies.

Proton magnetic resonance spectroscopy (1H MRS) was used to investigate intracranial tumours in vitro and in vivo. Biopsy specimens were studied from 47 patients, 11 of whom were also examined in vivo. Analysis was based on the signals from N-acetylaspartate (NAA), phosphocreatine plus creatine (Cr), choline-containing compounds (Cho), alanine (Ala), and lactate.

Proton MR spectroscopy in herpes simplex encephalitis: assessment of neuronal loss.

We present here the case of an 11-year-old boy with herpes simplex encephalitis diagnosed on the basis of clinical features, serology, and response to acyclovir, who relapsed after 3 weeks of therapy. In vivo proton magnetic resonance spectroscopy (1H MRS) of the brain, at 8 and 16 weeks after the onset of symptoms, showed abnormalities, most prominently a reduction in the N-acetylaspartate/choline ratio. The role of 1H MRS in assessing disease activity is discussed.

31P magnetic resonance spectroscopy of the human paediatric liver.

Localized 31P NMR spectroscopy was used to study the developing human liver in three neonates and one infant, all with neonatal intracranial problems, but normal liver function. A prominent resonance was present in the phosphomonoester (PME) region of the spectrum of the neonates; the PME/ATP ratio was 1.0 +/- 0.

Theoretical calculation of the longitudinal spherical aberration of rigid and soft contact lenses.

Although previous investigators have attempted to calculate the longitudinal spherical aberration inherent in soft and rigid contact lenses both on and off the eye, the use of inappropriate assumptions on which to base their calculations has left the problem unresolved. In this study, the longitudinal spherical aberration of both soft and rigid contact lenses was calculated surface by surface both in air and on the eye using a two-dimensional, exact ray tracing program. The erroneous assumptions made by previous investigators were avoided by using an elliptical model for the anterior corneal surface and assuming that the posterior surfaces of soft lenses aligned exactly with the anterior corneal surface after flexure onto the eye.

Some considerations concerning susceptibility, longitudinal relaxation time constants and motion artifacts in vivo human spectroscopy.

Artifacts due to localized susceptibility effects, variations in the spin-lattice relaxation time constants of signals and a mixing of signals arising from tissue motions can contaminate otherwise credible results. The sources and magnitude of some of these are discussed and their likely impact assessed, so that the necessity of incorporating additional measurements in an individual study can be demonstrated.

Preliminary exclusion of an X-linked gene in Leber optic atrophy by linkage analysis.

The maternal inheritance in Leber optic atrophy suggests that it may be caused by a cytoplasmic or mitochondrial defect. However, the strong male bias and the strict tissue specificity can not be readily explained by a single mitochondrial gene defect alone. Wallace suggested a hypothesis that the disease could be the result of an interaction between an X-linked gene and a mitochondrial DNA defect.

Effect of eye patching on the overnight corneal swelling response with rigid contact lenses.

In this study, 23 subjects wore a rigid extended wear (EW) lens overnight with a light pressure patch covering the eye while 19 subjects wore the same type of lens without patching. Corneal thickness measurements taken immediately upon awakening showed no significant difference in corneal swelling between the two groups. This result indicates that light pressure patching does not significantly affect the overnight corneal swelling found with rigid EW lenses, and it suggests that lagophthalmos during contact lens wear does not contribute significantly to the oxygen reaching the cornea during the closed-eye phase of overnight swelling studies.

31P magnetic resonance spectroscopy of the normal human brain: approaches using four dimensional chemical shift imaging and phase mapping techniques.

The use of four-dimensional chemical shift imaging to monitor phosphorus metabolites within the human brain is illustrated. Saturation effects are described, and acquisition conditions are discussed in relation to quantification and sensitivity. The effects of magnetic field variations on spectral parameters are assessed and the use of a field mapping technique is illustrated.

The benefits of increasing spatial resolution as a means of reducing artifacts due to field inhomogeneities.

All users of NMR equipment are familiar with the desirability of achieving as high a quality of field as possible. On the other hand, it is easy to forget that the field quality of relevance in both imaging and spectroscopy is that over individual voxels, and not the whole volume. This note demonstrates in practice how performance in poor fields is improved substantially by reducing voxel size (or increasing spatial resolution), offering a potential alternative to additional shimming under appropriate circumstances.

Use of phosphorus-31 MR spectroscopy to monitor response to chemotherapy in non-Hodgkin lymphoma.

Two patients with non-Hodgkin lymphoma of the femur were examined with 31P magnetic resonance spectroscopy (MRS) and proton magnetic resonance imaging before and during treatment with chemotherapy. Prior to treatment, 31P MRS of the tumor showed that in comparison to normal skeletal muscle, phosphocreatine was reduced, and phosphomonoesters (PME) and phosphodiesters were elevated. The 31P spectrum became similar to that of normal muscle after 40 days of treatment in both cases.

Four-dimensional chemical shift MR imaging of phosphorus metabolites of normal and diseased human liver.

Four dimensional chemical shift imaging was used to map the relative peak heights of phosphorus metabolites of the liver and overlying skeletal muscle of a normal subject and two patients. The technique provides 31P spectra localised on a voxel-by-voxel basis and may be valuable in mapping heterogeneous structural and metabolic changes in disease.

Four-dimensional phosphorus-31 chemical shift imaging of carcinoid metastases in the liver.

Four-dimensional chemical shift imaging was used to map spatial variations in phosphorus metabolites in a patient with carcinoid metastases in the liver. The results were compared to those from an age and sex matched volunteer, with no known previous history of liver disease. In the patient local abnormalities were observed.