The value of scintigraphy and computed tomography for the differential diagnosis of primary hyperaldosteronism.

Adrenocortical adenoma is the most common cause of primary hyperaldosteronism. Most tumours are small, less than 2 cm in diameter and, therefore, their localization may be difficult. We have compared two different methods, adrenal scintigraphy (AS) and computed tomography (CT) in the differential diagnosis of 12 patients with primary hyperaldosteronism. AS was performed using either [131I]cholesterol or 6-iodomethyl-19-norcholesterol during dexamethasone suppression. Of the patients, five showed a normal CT and symmetrical uptake of the isotope as AS. They were considered representative of bilateral hyperplasia. All showed good therapeutic response to spironolactone. Seven patients had an adrenocortical adenoma verified at operation. The CT finding indicated a tumour in five patients. This was correct in four, but in one patient the adenoma was found in the contralateral adrenal gland. In two patients with an adenoma, CT was considered normal. AS correctly indicated the tumour in all seven patients. The uptake was unilateral in six, and bilateral but clearly asymmetrical in one patient. The results indicate that AS is superior to CT in the pre-operative localization of aldosteroma. Although CT remains the primary method for the investigation of these patients, AS should be applied always when CT does not unequivocally indicate the presence and localization of an adrenal tumour.

An evaluation of different imaging chains in clinical chest radiography.

Six imaging techniques in clinical chest radiography have been evaluated: four film-screen combinations in the conventional grid technique and two combinations in the air gap technique. Five parameters characterising the quality of a chest radiograph were evaluated by three radiologists and one chest physician by using a nominal grading scale from -2 to +2 compared with the standard technique. The quality parameters judged were: the visibility of peripheral lung vessels, lung parenchyme, the pulmonary hilum, and lung structure behind the heart shadow, as well as the visibility of miscellaneous findings of clinical interest. The air gap technique was shown to be superior to the ordinary grid technique. The diagnostic quality of chest radiography does not necessarily deteriorate with the screen speed. However, statistically significant differences were noticed, even between techniques which had equal speed and physical resolution.

Visual detection and physical characteristics of roentgenographic systems. Investigations on chest imaging chains.

The relationship between physical characteristics (physical resolution, large object contrast and radiographic mottle) and visual detection parameters was evaluated in a water phantom. To measure visual observer performance a minified Snellen E-plate made of gold (three contrast zones) and a high contrast lead bar test pattern were investigated. A trial to test four types of equipment chains for chest radiography was further done with the E-plate technique by simulating a clinical radiography with an Alderson thorax phantom. The observer performance of the high contrast lead bar test pattern showed a good linear correlation to the physical parameters. However, none of the physical system-related parameters fully predicted the visual detectability when the equipment chains were investigated with the E-plate technique. In Alderson phantom studies the rare-earth screens and the air gap technique considerably reduced the radiation dose compared with that of the ordinary grid technique chest radiography, without impairing visual detectability significantly. The RP- and spotfilm techniques showed relatively poor properties of visual detectability.

Double contrast X-ray examination of stomach.

A comparison was made between three double contrast methods and the conventional method of X-ray examination of the stomach. 106 patets received ordinary barium sulphate together with effervescent granules. 119 patients were examined with a special barium sulphate preparation containing dissolved carbon dioxide (Baritop). The third group, 100 patients, received Baritop and effervescent granules, and 100 patients a conventional barium meal. The films were analyzed as to the quality of mucosal pattern demonstration, mucosal affinity of the contrast medium, and the degree of dilatation of the stomach and duo8num. In addition, the degree of interference by gas bubbles was estimated. The best results were obtained with the contrast medium containing carbon dioxide (Baritop).