The magnetic resonance (MR) imaging features of liposarcoma were correlated with histology in 15 patients. The MR findings for liposarcoma were not specific. The six myxoid liposarcomas and two atypical lipomatous tumors, however, had distinctive MR features, i.e., nodular masses of slightly heterogeneous intermediate to high signal intensity (SI), intermingled with high SI septa on T1-weighted images. The T2-weighted images demonstrated the relative reversal of these regional SI characteristics. Additionally, MR correctly identified the presence of fat in all eight cases in which it was pathologically present. The fat in two atypical lipomatous tumors was inseparable on MR from the subcutaneous fat. Magnetic resonance appears useful for preoperative staging and follow-up studies of liposarcomas. It may be helpful in identifying patients with myxoid liposarcoma and atypical lipomatous tumors who have longer survival times.

Adult↗

PubMedDate not supplied

Buckthorn neuropathy: effects of intraneural injection of Karwinskia humboldtiana toxins.

Ingestion of the endocarp of the coyotillo fruit, Karwinskia humboldtiana, a shrub of the buckthorn family, causes "Buckthorn neuropathy" in man and animals. Two neurotoxic compounds T496 and T544 were isolated from the endocarp and each toxin was dissolved in sesame oil and injected into the sciatic nerve of rats. The nerves were subsequently examined by teasing and as sections by light and electron microscopy. During the first 3--4 days after injection, oil droplets, probably containing toxin, were observed in the cytoplasm of Schwann cells with intact myelin sheaths. Clinical signs of weakness in the limb first appeared at 5--6 days and were accompanied by segmental demyelination mainly of the larger fibres. These observations suggest that the toxins have a primary action on Schwann cell metabolism. The results of local injection of purified toxins are discussed in relation to reports of nerve damage in animals following oral administration of the endocarp where intramyelin vacuole formation and segmental demyelination are prominent features.

Animals↗

PubMedDate not supplied

Relaxation times of normal and atrophied muscle.

Magnetic resonance imaging is being used to investigate physiological changes induced by microgravity. Using human (bed rest) and animal (tail suspension) models simulating zero gravity, muscle atrophy was studied. Despite significant physiological changes in muscle mass, distribution of blood flow, and muscle water, no changes in muscle proton relaxation times were found at several different resonant frequencies (6, 10, 20, and 200 MHz). These results suggest that observed changes in relaxation times as reported in pathologic studies are likely due to the pathological changes and not the accompanying muscle atrophy.

Animals↗