Val Dunn

A controlled magnetic resonance imaging study of corpus callosum thickness in schizophrenia

Two previous postmortem studies reported an increased thickness of the corpus callosum in schizophrenic patients compared to psychiatric controls. We report an in vivo study of the corpus callosum in schizophrenic patients (n = 38) and healthy controls (n = 41) using magnetic resonance (MR) brain imaging. A significant increase in mean callosal thickness was found in the middle and anterior, but not the posterior, parts of the callosal body. However, when the patients and controls were compared by gender and handedness, schizophrenic men were found not to differ from control men in callosal thickness, regardless of handedness, whereas schizophrenic women were found to have a highly significant increase in callosal middle and anterior thickness compared to control women. The data suggest that increased callosal thickness in schizophrenia is gender related, a factor that is not considered by postmortem studies. The implications of increased callosal dimensions in female schizophrenics are discussed.

Measurement of left ventricular mass in vivo using gated nuclear magnetic resonance imaging

Alterations of left ventricular mass occur in a variety of congenital and acquired heart diseases. In vivo determination of left ventricular mass, using several different techniques, has been previously reported. Problems inherent in some previous methods include the use of ionizing radiation, complicated geometric assumptions and invasive techniques. We tested the ability of gated nuclear magnetic resonance imaging to determine in vivo left ventricular mass in animals. By studying both dogs (n = 9) and cats (n = 2) of various sizes, a broad range of left ventricular mass (7 to 133 g) was examined. With a 0.5 tesla superconducting nuclear magnetic resonance imaging system the left ventricle was imaged in the transaxial plane and multiple adjacent 10 mm thick slices were obtained. Endocardial and epicardial edges were manually traced in each computer-displayed image. The wall area of each image was determined by computer and the areas were summed and multiplied by the slice thickness and the specific gravity of muscle, providing calculated left ventricular mass. Calculated left ventricular mass was compared with actual postmortem left ventricular mass using linear regression analysis. An excellent relation between calculated and actual mass was found (r = 0.95; SEE = 13.1 g; regression equation: magnetic resonance mass = 0.95 X actual mass + 14.8 g). Intraobserver and interobserver reproducibility were also excellent (r = 0.99). Thus, gated nuclear magnetic resonance imaging can accurately determine in vivo left ventricular mass in anesthetized animals.

Magnetic resonance imaging in Wallenberg's lateral medullary syndrome.

Four patients with a clinical diagnosis of Wallenbergs lateral medullary syndrome were studied with both Magnetic Resonance Imaging (MRI) and cranial Computed Tomography (CT). Using transverse images and both T1 and T2--weighted sequences, MRI demonstrated a medullary infarction not seen on CT in all four cases. MRI also demonstrated a coexisting cerebellar infarction in three cases which was unsuspected clinically and undetected by CT.

Magnetic resonance imaging in childhood disseminated encephalomyelitis

We report the magnetic resonance imaging features in two children with post-infectious disseminated encephalomyelitis. Magnetic resonance imaging dramatically demonstrated multiple white matter lesions in both children and resolution of lesions in conjunction with clinical recovery. These cases indicate that magnetic resonance imaging has considerable diagnostic utility in disseminated encephalomyelitis of childhood.

Bilateral focal Cortical atrophy and chronic ergotarnine abuse

A 67-year-old patient took 5 mg of ergotamine daily for 18 months. His headaches and dysphoria were greatly improved by stopping this drug. Brain imaging by CT and magnetic resonance techniques showed numerous atrophic lesions that may represent infarcts due to occlusion of superficial cortical vessels.

100 GATED MAGNETIC RESONANCE IMAGING OF THE IN VIVO HEART: DETERMINATION OF LEFT VENTRICULAR MASS IN DOGS

Alterations in left ventricular (LV) mass characterize many congenital and acquired cardiac diseases. Gated magnetic resonance (MR) imaging is a nonionizing, tomographic technique which permits delineation of cardiac morphology without contrast agents. To test the accuracy of MR-derived LV mass determinations, we imaged 10 anesthetized closed-chest dogs (median weight 20.3 kg, range 9-23 kg) using a 0.5 tesla, superconducting MR system with ECG gating. Transaxial images were acquired at end-diastole using a spin echo sequence with an echo time (TE) of either 13 or 20 msec. The heart was imaged sequentially from apex to base using a slice thickness of 10 mm. Endocardial and epicardial edges in each image were identified using an operator-interactive computer program, based upon a half-contour definition of edge points. The surface area of each cardiac slice was determined by planimetry and, after correcting for specific gravity (x 1.05), the individual slices were summed providing calculated LV mass. Post-mortem LV weights (median 83 gm, range 37.6-132.7 gm) were compared to calculated masses by linear regression analysis. We found a close correspondence between MR-derived and actual LV mass (r = .95, MR mass =.97 true mass + 6.2 gm, SEE = 7.8 gm). Thus, gated magnetic resonance imaging is capable of accurately determining in vivo LV mass. This noninvasive imaging technique should be clinically applicable in a variety of settings in which alterations of LV mass occur.