Physiologic intracranial calcification with hyperintensity on MR imaging: case report and experimental model.

CT and MR imaging showed basal ganglia calcification that appeared as high signal intensity on T1-weighted images of a patient with pseudohypoparathyroidism. MR imaging of an experimental model of calcium phosphate suspensions showed a signal similar to that seen in the patient. Additionally, T1 and T2 relaxation times of the solutions were measured and showed decreases in both parameters with increasing calcium phosphate concentrations. Intracranial calcification can appear as high signal intensity on T1-weighted images. An experimental model shows that the calcium salt decreases the T1 of surrounding water. Therefore, calcium, and possibly other elements, may induce paramagnetic susceptibility effects.

A possible role for MRI in polyarteritis nodosa: the "creeping fat" sign.

We describe a case of polyarteritis nodosa with diffuse abnormalities in subcutaneous fat by magnetic resonance imaging. These abnormalities returned to normal following treatment. Magnetic resonance imaging may have a role in the identification and diagnosis of systemic vasculitis.

Radionuclide, computed tomography, and digital imaging of duplicated inferior vena cava.

Duplication of the inferior vena cava (IVC) is not an uncommon vascular anomaly. We describe here the appearance of double IVC by radionuclide angiography, computed tomography (CT) scan, and digital angiography. It is important to confirm the presence of duplicated IVC, which is usually first seen on CT scan, because patients undergoing certain surgical procedures would be at greater risk for injury to the IVC as well as other complications.

Discrete peritoneal and pericardial implants of non-Hodgkin lymphoma--CT findings and review of the literature.

Peritoneal spread of non-Hodgkin lymphoma is rare: fewer than three percent of persons afflicted with this disease develop peritoneal spread. Pericardial involvement by non-Hodgkin lymphoma is equally rare. We report an instance of peritoneal and pericardial spread in a patient with non-Hodgkin lymphoma that was detected only by CT scan. The peritoneal lesions were not visible by ultrasound examination. A pertinent review of the literature is presented.

The effect of changing interpulse intervals on the negative chronotropic response to repetitive bursts of vagal stimuli in the dog.

The chronotropic responses to repetitive bursts of vagal stimulation were determined in open-chest, anesthetized dogs. Either 5 or 10 electrical pulses were included in each stimulus burst, and the interpulse interval (deltat) was varied over the range of 5 to 150 msec. As the frequency of the stimulus bursts was progressively changed, the sinoatrial (SA) nodal pacemaker cells became synchronized with the repetitive bursts of stimuli over a certain range of burst frequencies. The magnitude of this frequency range varied with deltat. For 5 and 10 pulses/burst, the values of deltat that produced the greatest magnitude of this frequency range were 30.2 and 24.3 msec, respectively. Also, over the range of values of deltat from 5 to 50 msec, the magnitude of the negative chronotropic effect of the vagal stimulus burst varied directly with deltat. It is likely that, as the interpulse interval is increased within the range of values, either more acetylcholine is released from the vagal nerve endings per pulse or there is less saturation of the receptors on the pacemaker cell membranes during each burst.

MR appearance of an arteriovenous hemangioma of the interventricular septum.

This paper presents an arteriovenous hemangioma of the interventricular septum in a patient with symptoms of ischemic heart disease. The MR, two-dimensional echocardiographic and selective left coronary arteriographic characteristics of the lesion are described.

Magnetic resonance and computed tomographic imaging in the evaluation of acute neuropsychiatric disease in systemic lupus erythematosus.

Magnetic resonance (MR) imaging and computed tomography (CT) are useful for the evaluation of central nervous system (CNS) lupus. This report describes the use of cranial MR and CT in 21 patients with systemic lupus erythematosus (SLE) with acute neuropsychiatric symptoms manifested by headache, seizures, focal neurological deficits, psychosis, or organic brain syndrome. Computed tomography was found to be insensitive and detected only diffuse atrophy (two cases), cerebral infarct (one case), and intracerebral haemorrhage (one case) in the 21 patients. Cranial MR images obtained with a General Electric 1.5 tesla Signa unit detected labile and fixed areas of increased proton intensity interpreted as focal oedema (eight cases), infarct (10 cases), haemorrhage (one), atrophy (seven), and acute sinusitis (two). Focal oedema was characterised by labile, high intensity lesions in the gray or white matter of the cerebellum, cerebrum, or brain stem, which completely resolved after aggressive corticosteroid treatment. Most high intensity reversible or fixed lesions evident on MR were not apparent on cranial CT images. In several patients sequential MR images were valuable in monitoring the efforts of treatment. Although histological confirmation of the high intensity brain lesions apparent on MR is desirable, prior necropsy studies suggest that pathological confirmation may be difficult owing to the paucity of recognisable brain lesions in patients with CNS lupus. It is concluded that for the evaluation of acute neuropsychiatric SLE MR is useful and provides more information than cranial CT.

Emergence of subtype Zaire Ebola virus in Gabon.

Gabon has recently been struck three times by Ebola hemorrhagic fever. The first isolate originating from the 1994 outbreak has been subjected to molecular characterization of its GP and VP24 genes. Sequence analysis demonstrates that the agent, Gabon-94 virus, belongs to subtype Zaire of Ebola virus. The isolate is closely related to the Kikwit-95 isolate, and both viruses seem to have evolved from a progenitor virus different from that of the Zaire-76 isolates. The relatively close relationship of all subtype Zaire viruses isolated at different geographical locations and up to 20 years apart suggests an extreme conservation in the yet unknown natural reservoir of Ebola viruses. The level of genetic variability in the human host might be different as indicated by the comparison of isolates from a single outbreak (Mayinga-76 and Eckron-76), but needs further investigation on clinical material of patients by PCR since both isolates have different levels of passages in tissue culture.

Dural ectasia as a cause of widening of the internal auditory canals in neurofibromatosis.

Patients with neurofibromatosis have an increased incidence of acoustic neuroma, which is often bilateral. We present three patients with neurofibromatosis and enlarged internal auditory canals secondary to dural ectasia, without associated acoustic neuromata. Air CT cisternography and Metrizamide CT cisternography was needed in differentiating dural ectasia from acoustic neuroma in two patients.