Val M. Runge

Dysmyelinogenesis in animal model of GM1 gangliosidosis

Magnetic resonance imaging (MRI), pathologic examinations, and biochemical analyses were performed on 2 different canine mutants with GM1 gangliosidosis (i.e., English Springer Spaniel and Portuguese Water Dog) and on age- and sex-matched controls. Serial MRI studies were also performed on a child with infantile-onset GM1 gangliosidosis. The affected dogs had abnormalities on MRI, including a relative increase in gray matter and an abnormal signal intensity of cerebral and cerebellar white matter observed on T2-weighted MRI. White matter changes on MRI were similar to white matter abnormalities observed in a 15-month-old boy with GM1 gangliosidosis. The weight ratio of white to gray matter from the frontal lobe was markedly reduced. Microscopic examination revealed characteristic ballooned neurons which stained lightly with Luxol-fast blue. The central cerebral and cerebellar folia white matter exhibited pallor and gliosis, while the corpus callosum and fornix stained normally with Luxol-fast blue. Axons appeared intact on Bodian staining. Ultrastructural studies revealed fewer myelinated axons in affected puppies. Total gangliosides in gray matter were elevated. Thin-layer chromatography demonstrated GM1 ganglioside as the predominant ganglioside. The amount of cerebrosides and sulfatides was reduced in the gray and white matter when compared to controls but the ratio in gray and white matter remained unchanged. Immunostaining of neutral glycolipids disclosed increased amounts of stage-specific embryonic antigen-1 glycolipid in gray matter. These findings suggest that canine models for GM1 gangliosidosis are associated with abnormal myelin development which may be similar to the human disease.

Fast imaging and other motion artifact reduction schemes: a pictorial overview

Since 1982, a number of techniques have been introduced for the purpose of reducing motion artifacts in magnetic resonance imaging. These are reviewed with an emphasis on effectiveness and clinical practicality. Physical restraints, data averaging, and gradient moment nulling are widely used at present. Fast imaging techniques, particularly with the advent of saturation pulses (to diminish arterial and venous pulsation artifacts), may be utilized in the future to obtain diagnostic quality abdominal and pelvic images during breath holding.

Experimental trials with Gd(DO3A)—a nonionic magnetic resonance contrast agent

Gd(DO3A), a member of a new family of nonionic MRI contrast agents, was evaluated in vivo in a rat model. In 10 animals, enhancement of an intracerebral glioma was studied following Gd(DO3A) injection. Correlation with tissue pathology was obtained in all cases. Comparative studies of renal enhancement were performed in 15 animals, utilizing disodium Gd(DTPA)2-, sodium-Gd(DOTA)-, and Gd(DO3A). With the glioma model, Gd(DO3A) administration provided enhancement of tissue with an altered blood brain barrier, thus permitting identification of the bulk of the neoplastic lesion. Comparative studies revealed that enhancement of normal renal medulla was equal or superior with Gd(DO3A).

The efficacy of tilted axial MRI of the CNS

The angle between the straight axial plane and the orbito-meatal line was measured in 156 consecutive magnetic resonance examinations. Inconsistent head positioning caused this angle to vary by as much as 44 degrees. Careful positioning of the patient by the technologist can minimize this variability, leading potentially to improved image interpretation. To assess the merit of a standardized orientation for MR examinations of the head, straight axial and tilted axial MR scans were compared in 34 patients. The tilted images were obtained parallel to the orbitomeatal line and were found to be superior for visualization of the cerebellum. When correlative x-ray CTs are available or when an abnormality in the posterior fossa is suspected, tilted axial MR scans should be employed.