Pituitary fossa: chemical shift effect in MR imaging

The effect of chemical shift on magnetic resonance (MR) imaging of the pituitary fossa was studied. Healthy volunteers underwent conventional MR imaging of the pituitary fossa and then imaging with the frequency-encoding gradient reversed or with the phase- and frequency-encoding gradients interchanged. Comparison of the image pairs in each subject showed that the thin, black stripe evident at the water-fat interface within the pituitary fossa was altered when the gradients were changed. Therefore, the low-intensity signal within the pituitary fossa is a chemical shift misregistration effect.     

Anulus fibrosus in bulging intervertebral disks

In this investigation the association of radial tears of the anulus fibrosus and bulging of the intervertebral disk was studied. An index of disk bulging was measured in sagittal anatomic sections in 149 lumbar disks from 31 cadavers. The indexes of disk bulging were correlated with stages of disk development and the presence of an annular tear. The largest disk-bulging indexes were always associated with radial tears of the anulus. Eighty-four percent of the disks with radial tears had disk-bulging indexes greater than 2.5 mm. Most normal adult disks had an index of less than 2.5 mm. The results challenge the concept that the anulus fibrosus is intact in bulging disks, although ruptured in herniated disks.     

Osteopetrosis: MR characteristics at 1.5 T

Four patients with proved osteopetrosis (three with the infantile malignant form and one with the benign form) were examined with magnetic resonance imaging at 1.5 T. All patients were studied in the coronal and sagittal planes using both short and long repetition time/echo time sequences. The infantile malignant form was characterized by a complete lack of signal from the marrow alternating with a signal intensity equivalent to that of the intervertebral disks, resulting in a "stepladder" appearance. In the benign form or after successful marrow transplantation in the infantile malignant form, intermediate or high signal intensity in the vertebrae was noted, suggesting the presence of some marrow elements.     

Lack of pharmacokinetic and pharmacodynamic interaction between rizatriptan and paroxetine

Rizatriptan is a potent, oral 5-HT(1B/1D) agonist with a rapid onset of action being investigated for the acute treatment of migraine. This study examined the clinical and pharmacolinetic interaction between rizatriptan and the selective serotonin reuptake inhibitor, paroxetine. In this two-period crossover study, 12 healthy young subjects (6 males and 6 females) received 1 mg rizatriptan following 14 days of treatment with placebo or paroxetine (20 mg once daily). Plasma was sampled for rizatriptan and N-monodesmethyl rizatriptan, a minor but active metabolite of rizatriptan. Safety evaluations included monitoring for adverse events, vital signs, and visual analog scale assessment of mood. Plasma levels of rizatriptan and N-monodesmethyl rizatriptan were not altered when rizatriptan was administered with paroxetine compared to the placebo. Clinically, coadministration of rizatriptan with paroxetine was well tolerated. Blood pressure, heart rate, and temperature changes during the observation period did not differ to a clinically significant degree when rizatriptan was administered with paroxetine compared to the placebo. No effects on mood occurred following treatment with the combination compared to rizatriptan alone. Adverse events following rizatriptan administration with paroxetine were similar to those reported when rizatriptan was given with the placebo.