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.     

Differences in skin-prick and patch-test reactivity are related to the heterogeneity of atopic eczema in infants

Current data indicate an obvious relation between food allergy and atopic eczema in infants. However, diagnostic methods for food allergy need to be supplemented. The objective was to study the relevance of food patch testing in the detection of food allergy in correlation with oral food challenge and skin prick tests in atopic infants. Infants with atopic eczema (n = 113) aged 2–24 months were studied. Each patient was subjected to double-blind, placebo-controlled, or open cow's milk challenge, and skin prick and patch tests. Polysensitization, as judged from skin test results, was common in patients with atopic eczema (79/113). Cow's milk challenge was positive in 54/113 infants; reactions were immediate in 36/54 and delayed in 18/54. Immediate-type reactions were associated with skin prick test positivity and delayed reactions with patch test positivity. Altogether 26% of the cow's milk-allergic infants were detected by patch testing only. Patch testing improved the accuracy of skin testing in the diagnosis of food allergy in infants with atopic eczema, but it needs to be standardized. Polysensitization appears to be more common than generally believed among infants with atopic eczema.     

Basophil histamine release and lymphocyte proliferation tests in latex contact urticaria

Basophil histamine release and lymphocyte proliferation tests were examined with latex allergen prepared from surgical gloves in 15 patients with latex contact urticaria. The basophil histamine release test (BHRT) yielded positive results in 13/14 (93%) patients, whereas commercial latex RAST was positive in only 9/15 (60%) patients. Lymphocyte proliferation test (LPT) was positive in 3/15 (20%) patients, suggesting that cell-mediated immune reactions may also occur in latex allergy. However, patch tests to latex were negative and neither were epidermal Langerhans cells able to present latex antigen to T lymphocytes in vitro.