The neuroendocrine challenge paradigm in headache research

The neuroendocrine challenge paradigm provides a "window" on central neurotransmitter function in vivo. This strategy is based on the premise that the sensitivity of certain central receptors can be inferred from the magnitude of the hormonal response to specific pharmacologic probes. For example, the serotonin (5HT) receptor agonist m-chlorophenylpiperazine (m-CPP) stimulates the release of cortisol and prolactin and induces migraine-like headaches. We have previously reported that the headache and cortisol responses to m-CPP are highly correlated, which may implicate a disturbance in central serotonergic neurotransmission in the pathogenesis of migraine. As pharmacologic probes with greater specificity for 5HT receptor subtypes become available, we may be able to elucidate these mechanisms with greater precision. The neuroendocrine challenge methodology is also applicable to the study of other neurotransmitter systems and other headache disorders.     

Hepatocellular carcinoma: assessment of resectability by computed tomography and ultrasound

A retrospective review of the CT and ultrasound scans from examinations of 30 patients who had hepatocellular carcinoma (hepatoma) was undertaken with special emphasis placed on evaluation of hepatic distribution of tumor, vascular invasion, and extrahepatic spread. Although both CT and ultrasound detected hepatoma in 29 of 30 patients (96%), CT showed more extensive hepatic parenchymal involvement in eight of the patients. Vascular invasion was seen more frequently with ultrasound than with CT. Invasion into the main portal vein was seen by ultrasound in 11 of 30 patients (37%). Extrahepatic spread of tumor was much more frequently detected by CT and was present in 21 of 30 patients (70%). A reasoned approach to the diagnostic workup of hepatomas that will minimize invasive procedures and unnecessary surgery is presented.     

Left ventricular volumes measured by MR imaging

We assessed the potential of proton magnetic resonance (MR) imaging for accurately measuring left ventricular volumes using 15 latex casts of excised human left ventricles. The casts were submerged in water to stimulate the endocardial left ventricular cavity interface in in vivo imaging conditions. Tomographic image sections perpendicular to the long axis of the cast were obtained, spanning each cast from apex to base. Simpson's rule was used to calculate the cast volumes. Correlation between the actual cast volumes (as measured by the displacement method) and the calculated volumes using MR imaging for the 15 casts was excellent. Our data demonstrate that MR imaging accurately measures cardiac chamber volumes in this in vitro model.     

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.