Harvey Eisenberg

Digital Radiography: An Overview

A new class of diagnostic imaging systems, loosely termed Digital Radiography, has emerged during the past year from the laboratory into the forefront of radiological practice. These systems have in common the acquisition of a two dimensional projection image in digital format but include a variety of detectors, techniques and applications. Digital radiography apparatus are conveniently divided into point scanned, line scanned and area systems. Each system is briefly described and its performance capabilities are reviewed. Digital video radiography is given added emphasis due to its rapid development for intravenous angiography. The key requirements and present limitations of major components of the video system are noted. Gross specifications of the next generation of computers for digital radiography are postulated.

Selective arteriography, venography and venous hormone assay in diagnosis and localization of parathyroid lesions☆☆☆

Abstract The results of parathyroid arteriography, venography and venous hormone assay were evaluated in 50 patients with proved hyperparathyroidism. Complete selective venous sampling representative of drainage sites in both upper and lower poles of the thyroid lobes was obtained in 94 per cent of the patients and was found to be an innocuous technic. Venous sampling alone provided correct localization and differentiation of parathyroid lesions in all patients without prior exploration. Venous sampling followed by limited arteriography provided specific identification of abnormal solitary parathyroid glands in 17 of 20 patients with unsuccessful prior explorations. Selective-magnification thyroid arteriography was positive in all patients retrospectively, but only a 77 per cent prospective accuracy could be achieved because of difficulty in differentiating thyroid lesions from parathyroid lesions. Venography without hormone assay was only occasionally helpful. These technics provided a significant contribution to the management of the previously explored patients. Furthermore, selective venous hormone assay should be considered in the routine preoperative evaluation of patients with primary hyperparathyroidism.

ACTH Stimulation of Adrenal Epinephrine and Norepinephrine Release

Epinephrine (E) and norepinephrine (NE) levels were measured simultaneously in the adrenal veins of 6 patients before and after stimulation with 0.25 mg beta 1-24 ACTH. In 1 patient with Cushings syndrome, E and NE were also measured before and 30 min after dexamethasone. There was a significant increase in NE and E secretion (p less than 0.002) from both adrenal glands after ACTH stimulation. In the patient with Cushings syndrome, there was also a slight increase in plasma E levels after dexamethasone. It is postulated that ACTH stimulated NE and E secretion by augmenting blood flow through the adrenals and by induction of tyrosine hydroxylase and dopamine beta-hydroxylase, although a direct effect of ACTH on NE and E secretion cannot be excluded. It is also possible that the increase in adrenal catecholamine secretion after ACTH may be due to ACTH augmentation of catecholamine secretion by endogenous opioids such as beta-endorphin.

Diagnosis of pituitary tumors by hormone assays and computerized tomography

Abstract One hundred and seventy patients with endocrine abnormalities, 29 males and 141 females, were studied by computerized tomography (CT) scanning of the pituitary and by pituitary hormone assays including basal and stimulated hormone concentrations in the blood. Pituitary macroadenoma was observed in 40 of the 170 patients, microadenoma in 49, primary empty sella in 46, secondary empty sella in 25, including 20 of the 40 patients with macroadenoma after surgical removal or radiation therapy of the tumor. Suprasellar tumor was present in four patients. In 23 women with menstrual abnormalities and 3 men with impotence and hyperprolactinemia, the results of CT scanning were normal. Of the 40 patients with macroadenoma, 24 presented with a hyperfunctioning syndrome (acromegaly or hyperprolactinemia). Among the 49 patients with microadenomas, 46 had the amenorrhea-galactorrhea syndrome, one male presented with acromegaly and one with Cushings disease, and one female also had Cushings disease. Primary empty sella was associated with the amenorrhea-galactorrhea syndrome in females and impotence in males. Only four female patients demonstrating an empty sella were asymptomatic. Distinctive biochemical findings were identified in certain groups of patients with different pituitary pathologic features. CT scanning was found very useful in the assessment of the size of the tumor, its suprasellar or parasellar extension and response to therapy, and in differential diagnosis of tumor and empty sella. Disappointing results were obtained in patients with endocrine abnormalities and normal results of CT scanning, and in patients following surgical treatment for a pituitary tumor, when the identification of recurrent tumor was impossible from a single examination. It is concluded that CT scanning is the most advanced technique in the diagnosis of anatomic pituitary abnormalities, and it should replace the traditional invasive diagnostic procedures.

Measurements of Reciprocity Law Failure in Green-Sensitive X-Ray Films

Reciprocity law failure was measured for four brands of medical x-ray films exposed with intensifying screens. Three of the films are green light-sensitized for use in combination with green light-emitting rare-earth screens. These films showed larger reciprocity failure effects than one conventional blue-sensitive film, Dupont Cronex-2. Development conditions had a small effect on reciprocity failure. As part of the investigation, a detector was constructed with a response that accurately monitors the light emission from the double screen-cassette combination over a wide range of x-ray photon energies.

Magnification Mammography: A Low-Dose Technique

Image quality and radiation exposures of a mammographic technique using direct radiographic magnification at 2 X with a microfocal spot x-ray tube and a fast, double screen-film system were compared to those of conventional contact mammography with a rare-earth screen and molybdenum target tube. The results indicate that the magnification technique yields improved detection of microcalcifications and comparable visualization of soft-tissue details, with a large reduction in radiation exposure. This technique has demonstrated the feasibility of carrying out high-quality mammography with an entrance dose of 1.35 X 10(-3) Gy (135 mrad) for the average breast.

The LSF and MTF of rare-earth oxysulfide intensifying screens.

The line spread function (LSF) and modulation transfer function (MTF) of 9 rare-earth screen/film systems were measured and compared with those of two fast calcium tungstate systems, using double-emulsion films sandwiched between two screens and mounted in regular cassettes. The LSFs were found to fit exponential functions. These results indicate that the increased sensitivity of rare-earth phosphors over calcium tungstate can be used to construct screens with a higher MTF or increased speed. The fast rare-earth systems allow the use of smaller focal spots for increased resolution while reducing the radiation dose to the patient.

Response of Thyroid Hormones in Peripheral and Thyroid Venous Blood to TRH Administration in Man

Thyroid vein and cubital vein samples were collected simultaneously in 6 moderately hypercalcemic patients and 1 eucalcemic hypothyroid patient, and thyroid hormones were measured in the serum in the basal state, as well as 30 and 60 min after intravenous administration of TRH. No gradient was detectable between peripheral and thyroid blood in the case of T4, and no significant changes were observed following TRH. The levels of T3 were higher in the thyroid venous effluent than in the periphery and a marked increase occurred following TRH. Serum thyroglobulin also increased following TRH, but there was no peripheral vs. thyroid gradient. Calcitonin demonstrated a marked positive gradient in the thyroid vein compared to the periphery, but no change was observed following TRH. It is concluded that the patterns of response of individual thyroid hormones reflect differences in their secretion and, specifically, that intrathyroid conversion of T4 to T3 occurs during the thyroid hormone secretion.

Reciprocity Law Failure In Green Sensitive X-Ray Films

Reciprocity law failure was measured for four brands of medical X-ray films exposed with intensifying screens. Three of the films are green light sensitized for use in combination with green light emitting rare-earth screens. These films showed larger reciprocity failure effects than one conventional blue sensitive film, Dupont Cronex-2. The development conditions had a small effect on reciprocity failure. The effect of reciprocity failure on the measurements of physical image quality parameters is discussed.

The Value Of Making the 0.2mm Microfocus Tube the Standard for Routine Direct Magnification Angiography

For frequent visualization of the fine blood vessels within the brain substance, geo-metric magnification is required at angiography. However, full skull geometric magnification on large size film changers may also prove insufficient for visualization of these vessels. Further magnification of most cerebral arteries in lateral projection can be obtained without compromising full skull coverage and without additional radiation exposure! This is accomplishable when a true 0.2mm focal spot of uniform intensity distribution is substituted for the nominal 0.3mm and the usual position of the tube and film changer is reversed relative to the skull. This tube-changer reversal contradicts the standard technique for non-magnification radiography. The additional capacity for gaining moderately high magnifications with the 0.2mm focal spot is also advantageous. It is recommended that the 0.2mm focal spot become the standard tube manufactured for magnification neuroangiography. If a second focal spot accompanies it, either a 0.1mm size can be used for higher magnifications or a high kilowatt loading larger spot can be matched with it for general radiographic or conventional angiographic use.