Medical nuclear magnetic resonance imaging: I. Physical principles.

For over 30 years, nuclear magnetic resonance (NMR) spectroscopy has been used for chemical analysis and for studying molecular behavior, but NMR imaging is a recent addition to the methods available to radiologists for investigating the interior of the body. It uses radiofrequency radiation in the presence of a magnetic field to produce anatomical cross sections. The images may be simple maps of the concentration of the hydrogen nucleus, or they may depend on tissue relaxation times, which describe how rapidly hydrogen nuclei exchange energy with their surroundings. In this article, the basic concepts and physical principles of conventional NMR spectroscopy are introduced. In subsequent articles, the various approaches to producing NMR images will be outlined, and the types of information obtainable from NMR scanners will be discussed.

The pituitary fossa in Cushing's syndrome. A retrospective analysis of 93 patients.

A retrospective analysis of the pituitary fossa in 93 patients with Cushing's syndrome is presented. Radiological evidence of a pituitary tumour was found in 20 of 86 patients with pituitary-dependent disease (23%). In 11 of the 20 patients, the diagnosis depended on analysis of lateral tomograms. None of the seven patients with disease which was not pituitary-dependent had evidence of an abnormal sella. One of 20 controls without known endocrine disease had an abnormal sella.

Radiological and histological findings in six patients with alpha-chain disease.

Detailed radiological and histological features of alpha-chain disease are presented against a background of the clinical and biochemical findings. The separation of this syndrome from other varieties of "Mediterranean" lymphoma is emphasized. The radiologist should in some instances be able to suggest the diagnosis in his differential diagnosis of abnormalities seen on examination of the small bowel. The histopathologist should be able to provide a diagnosis from examination of a peroral jejunal biopsy. One patient with this relatively uncommon disease had evidence of a hypertrophic osteoarthropathy. Two of the six patients had a transient episode of acute abdominal distension which resolved on conservative management.

A comparison of radiography and radioisotope scanning in the detection of Paget's disease and in the assessment of response to human calcitonin.

In eight patients with symptomatic Paget's disease, radiographs and radioisotope bone scans have been compared before treatment by high dose synthetic human calcitonin (CIBA 47175-Ba) and three months and 12 months later. In six patients quantitative radioisotope scans allowed calculation of relative radioactivity in normal bone, Paget's disease and bone adjacent to osteoarthritic joints. Comparison of radiographs and scans showed 69 sites diagnosed as Paget's disease on both examinations; nine sites showed radiographic changes of Paget's disease but had negative radioisotope scans and two sites were abnormal on the scan but radiologically normal. One of these two reverted towards normal during treatment with calcitonin. Comparison of analogue scans done at three months and 12 months with initial scans showed diminished uptake in Paget's disease compared with normal bone, and quantitation showed this was due to decreased absolute uptake in Paget's disease and a slight increase in normal bone. Osteoarthritic bone showed no significant response to calcitonin.