Magnetic resonance imaging of the brainstem: normal structure and basic functional anatomy

Normal structure and basic functional anatomy of the brainstem were studied using anatomic sections obtained with a cryomicrotome whole-organ sectioning technique. Major tracts and nuclei were identified and their function summarized. Magnetic resonance imaging of the brainstem was performed on 10 normal volunteers. By comparing these images with the corresponding anatomic sections, normal structures, including major tracts and nuclei, were identified. Knowledge of location and function of clinically important brainstem nuclei and tracts is necessary for optimal magnetic resonance image interpretation.     

Pulse sequence optimization for MR imaging using a paramagnetic hepatobiliary contrast agent

Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.     

Use of femur length/abdominal circumference ratio in detecting the macrosomic fetus

The femur length/abdominal circumference ratio, expressed as FL/AC X 100, was determined in 156 fetuses and evaluated as a predictor of fetal macrosomia within one week prior to delivery. The normal range (mean +/- 2 SD) in the 105 normal-weight fetuses was 22.0 +/- 2, while the normal range in the 51 macrosomic fetuses was 20.5 +/- 2; these differences were highly significant (P = less than .0001). The predictive power of a positive ratio was 68%, with a sensitivity of 63%. This ratio was particularly useful in the subset (n = 9) of macrosomic fetuses whose mothers were diabetic, correctly identifying 89% of this group. Because it is age independent, this ratio should prove most helpful in identifying fetuses at risk for macrosomia in patients whose dates are not known, since it may become abnormal before the fetal weight falls above the 90th percentile at term (3,900 g). In patients whose dates are known, early fetal macrosomia is best predicted by evaluating the abdominal circumference against normal standards for age.     

CHANGES IN PULMONARY VASCULATURE IN LUNG DISEASES WHICH LEAD TO PULMONARY HYPERTENSION

The pulmonary vasculature was studied in lung biopsy/autopsy specimens of 20 cases, in conditions likely to lead to pulmonary hypertension. The changes were classified as per Edward and Heath classification and morphometric measurements to gauge medial and intimai hypertrophy were done. Medial hypertrophy was found to be the earliest and commonest change in all cases, irrespective of the pathogenic mechanism of pulmonary hypertension. Variable changes specific to various arteriopathies/vasculopathies were noted.KEYWORDS: Hypertension pulmonary, Pulmonary artery     

Dietary factors in oral leukoplakia and submucous fibrosis in a population-based case control study in Gujarat, India

OBJECTIVES: To investigate the relationship of specific nutrients and food items with oral precancerous lesions among tobacco users.
DESIGN: A population-based case-control study. SETTING: Villages in Palitana taluk of Bhavnagar district, Gujarat, India.
SUBJECTS AND METHODS: An interviewer-administered food frequency questionnaire, developed and validated for this population, was used to estimate nutrient intake in blinded, house-to-house interviews. Among 5018 male tobacco users, 318 were diagnosed as cases. An equal number of controls matched on age (±5 years), sex, village, and use of tobacco were selected.
MAIN OUTCOME MEASURES: Odds ratios (OR) from multiple logistic regression analysis controlling for relevant variables (type of tobacco use and economic status).
RESULTS: A protective effect of fibre was observed for both oral submucous fibrosis (OSF) and leukoplakia, with 10% reduction in risk per g day^-1 ( P < 0.05). Ascorbic acid appeared to be protective against leukoplakia with the halving of risk in the two highest quartiles of intake (versus the lowest quartile: OR = 0.46 and 0.44, respectively; P < 0.10). A protective effect of tomato consumption was observed in leukoplakia and a suggestion of a protective effect of wheat in OSF.
CONCLUSION: In addition to tobacco use, intake of specific nutrients may have a role in the development of oral precancerous lesions.