MR detection of hippocampal disease in epilepsy: factors influencing T2 relaxation time.

Purpose: To assess the reproducibility and stability of hippocampal T2 relaxation times and examine the effects of patients' age, seizures, and duration of epilepsy on this measure.

Methods: Hippocampal T2 relaxation times were measured in 63 patients with chronic epilepsy (55 with partial and 8 with idiopathic generalized seizures) using a Carr-Purcell-Meiboom-Gill sequence, echo times 22 to 262 millisecond, on a 1.5-T clinical MR imaging system.

Clinical diversity of pyruvate dehydrogenase deficiency.

Clinical features, magnetic resonance, and biochemical studies are reported in 7 children with pyruvate dehydrogenase (PDH) deficiency. These findings confirm the diverse clinical presentation of this condition, although neurological abnormalities are consistent features. Imaging results are also varied.

Quantitative MR relaxometry study of effects of vigabatrin on the brains of patients with epilepsy.

Neurotoxic changes have been found in the brains of dogs and rats treated with the antiepileptic drug vigabatrin, and these can be demonstrated in vivo by MRI. Quantification of T2 signal by relaxometry is more sensitive than visual assessment of T2-weighted images in revealing changes in T2 signal. We have therefore undertaken a quantitative MR study of 45 patients with refractory partial seizures during a prospective, randomised, double-blind trial of vigabatrin (1.

Functional magnetic resonance imaging of focal seizures.

Magnetic resonance imaging (MRI) can now provide maps of human brain function with high spatial and temporal resolution. We aimed to establish whether this noninvasive technique could also map the cortical activation that occurs during focal seizures. In order to do this, we used a conventional 1.

1H magnetic resonance spectroscopy in the investigation of intractable epilepsy.

We have been using proton magnetic resonance spectroscopy (1H MRS) in the investigation of adults and children with intractable epilepsy. Spectra were obtained from 2 x 2 x 2 cm cubes in the medial region of the temporal lobe, and were analyzed on the basis of signals from N-acetylaspartate (NAA), creatine+phosphocreatine (Cr), and choline-containing compounds (Cho). In comparison with control subjects, the epilepsy patients as a group show significant reductions in the NAA signal and in the NAA/Cho+Cr ratio, with increases in the Cho and Cr signals.

Detection of hippocampal pathology in intractable partial epilepsy: increased sensitivity with quantitative magnetic resonance T2 relaxometry.

Abnormal T2-weighted signal intensity in the hippocampus may be difficult to detect visually, and T2 mapping provides an objective means of assessing signal abnormality. We investigated 50 adult outpatients suffering from intractable partial epilepsy with MRI optimized to detect hippocampal and cortical gray matter abnormalities, and with MR T2 relaxation mapping. The range of normal hippocampal T2 relaxation times is small (99 to 106 msec), and the measurements are reproducible between observers.

Functional mapping of activated human primary cortex with a clinical MR imaging system.

Functional activation of the human brain can be visualized with magnetic resonance (MR) imaging, but most studies so far have used echo-planar imaging or magnetic fields of 2 T and above, neither of which are at present widely available. The authors used a standard 1.5-T MR imaging system to map regions of the brain that are activated with visual and motor tasks, using a long echo time (60 msec) fast low-angle shot sequence.

Early detection of abnormalities in partial epilepsy using magnetic resonance.

The incidence of brain abnormalities determined by magnetic resonance in 30 consecutive children presenting with intractable complex partial seizures is reported. Images were optimised to visualise the hippocampus and cortical grey matter. Abnormalities of the hippocampus or temporal lobe were seen in all 19 children with clinical features of temporal lobe epilepsy and in six of the seven children with clinically unlocalised epilepsy.

Optimizing the diagnosis of hippocampal sclerosis using MR imaging.

Purpose: To establish the optimal imaging parameters and MR features of hippocampal sclerosis.

Methods: Twenty-five outpatients with intractable temporal lobe epilepsy and 10 control subjects were studied at 1.5T.

Placental microvascular changes in twin pregnancies with abnormal umbilical artery waveforms.

Objective: To determine whether there is a relationship between umbilical artery Doppler waveforms and placental histology in twin pregnancies.

Methods: The placental vasculature was examined histologically in 41 cases of twin pregnancy in women who had undergone antenatal Doppler umbilical artery waveform analysis.

Results: Those fetuses with abnormal systolic-diastolic ratios (S/Ds) showed a reduction in the placental tertiary stem villi arterial vessels compared with fetuses with normal S/Ds.

Magnetic resonance spectroscopy shows increased brain glutamine in ornithine carbamoyl transferase deficiency.

We have performed localized in vivo proton magnetic resonance spectroscopy on two females with ornithine carbamoyl transferase deficiency during episodes of acute hyperammonemic encephalopathy with focal neurologic abnormalities. Spectra obtained from 2 x 2 x 2 cm cubic volumes at relatively long (135-ms) echo times contain additional signals that are characteristic of glutamine and indicate that glutamine is present in very high concentrations in the brain. The findings are consistent with the hypothesis that intracerebral accumulation of glutamine contributes to the encephalopathy associated with hyperammonemia.

Proton magnetic resonance spectroscopy studies in lactic acidosis and mitochondrial disorders.

Congenital lactic acidosis form a large group of disorders that are commonly associated with profound neurological dysfunction. Difficulties are frequently encountered in establishing a diagnosis, and the mechanisms underlying brain damage are poorly understood. We have performed proton magnetic resonance spectroscopy (1H-MRS) on 24 patients under investigation for suspected metabolic disorder, and have compared the MRS observations of brain lactate with measurements of cerebrospinal fluid (CSF) lactate.

An examination of stressors in the patient undergoing cardiac electrophysiologic studies.

This study was undertaken to (1) identify stressors that medically treated patients who undergo cardiac electrophysiologic studies (EPS) experience from the points of view of patients and the staff nurses who care for them, (2) compare patients' and nurses' perceptions of such stressors, and (3) evaluate a tool developed by the investigator, the EPS Stressor Scale. Stressors were measured by scores on a scale from one to five. Demographic and health-related information was also obtained from patient subjects.

Localized 1H NMR spectroscopy in Canavan's disease: a report of two cases.

Two children with Canavan's Disease, an autosomal recessive leukodystrophy, were studied by localized 1H spectroscopy. The N-acetylaspartate (NAA) signal intensity was high relative to other metabolite signals, and the signal intensity from choline-containing compounds was low. These findings are discussed in relation to a possible role for NAA in normal myelination.

Fetal umbilical artery velocity waveforms and subsequent neonatal outcome.

Flow velocity waveforms (FVWs) from the fetal umbilical artery were recorded from 2178 pregnant women over a 6-year period. All of them had an obstetric factor indicating increased risk of fetal compromise. A total of 6749 studies was recorded.

Approaches to editing, assignment and interpretation of proton spectra.

Clinical 1H spectroscopy of the brain is complemented by parallel analyses of biopsy specimens and by studies of animal models of disease. 1H spectroscopy has been carried out on perchloric acid extracts of biopsy specimens from patients with intracranial tumours. The data suggest that clinical spectroscopy may be useful in the identification and grading of these tumours.

Doppler umbilical artery studies in the twin-twin transfusion syndrome.

Eleven patients with twin pregnancies were identified as having twin-twin transfusion syndrome on the basis of like-sex twins with monochorionic placentation and umbilical venous blood hemoglobin differences exceeding 50 g/L at delivery. Umbilical artery velocity-time waveform studies had been performed in these pregnancies as part of a large series of 456 twin pregnancies. In all 11 cases, the systolic-diastolic (S-D) ratio differences between the twins were less than 1 unit (mean 0.

Umbilical artery waveforms in triplet pregnancy.

Twenty patients with triplet pregnancies underwent continuous-wave Doppler ultrasound umbilical artery waveform studies as part of a multiple-pregnancy surveillance program. One or more infants was small for gestational age in nine of these triplet pregnancies. In all of these cases, at least one abnormal umbilical artery velocity waveform was present.

Reduced fetal platelet counts in pregnancies with abnormal Doppler umbilical flow waveforms.

Fetal and maternal platelet counts were correlated with antenatal assessment of the umbilical-placental waveform. Forty singleton pregnancies were studied using Doppler ultrasound, and placental resistance was categorized as normal or high according to the systolic/diastolic ratio. We performed platelet counts on maternal and cord blood taken at the time of cesarean section.

The effects of prostacyclin and thromboxane analogue (U46619) on the fetal circulation and umbilical flow velocity waveforms.

In placental insufficiency and pre-eclampsia the relative production rates of prostacyclin and thromboxane by the placenta and umbilical vessels are altered and the Doppler umbilical flow velocity waveform shows a high resistance pattern. To investigate the control of umbilical placental blood flow by those eicosanoids either prostacyclin (10 micrograms/min), or the thromboxane analogue U46619 (10 ng/min) was infused into the distal aorta of 12 chronically catheterized fetal lambs at day 125. Thromboxane produced a rise in mean arterial pressure and a rise in the systolic diastolic ratio of the umbilical artery flow waveform (2.

Umbilical artery flow velocity waveforms and twin pregnancy outcome.

Two hundred seventy-two twin pregnancies were studied by analysis of the fetal umbilical artery waveforms recorded using continuous-wave Doppler ultrasound. After the first 100 cases, a management strategy was adopted whereby all twin gestations would be studied between 28-32 weeks' gestation and the results made available to the referring obstetrician, thereby influencing clinical management. Perinatal mortality and morbidity, in pregnancies with both fetuses alive at 28 weeks' gestation, were compared between the patients studied in the first group of 100 and those studied after the Doppler examination was introduced as a clinical service.

Low-dose aspirin therapy improves fetal weight in umbilical placental insufficiency.

A randomized, placebo-controlled, double-blind trial was carried out to evaluate the fetal benefits of low-dose aspirin (150 mg/day) as a treatment of placental insufficiency during the last trimester of pregnancy. Forty-six women referred for study because there was concern about fetal welfare were found to have an elevated umbilical artery wave form systolic/diastolic ratio. Mothers with severe hypertension were excluded because fetal condition would not necessarily be the dominant determinant of obstetric decision making.