Pulmonary masses: contrast enhancement.

Radiographic studies to discriminate benign from malignant pulmonary masses have previously focused on the morphologic and, more recently, the computed tomographic (CT) attenuation characteristics of the lung mass. Experience with the use of an intravenously administered iodinated contrast medium in examining the enhancement properties of lung masses was reviewed. Distinctive differences in the vascularity, pathophysiologic features, and pharmacodynamics of malignant versus benign pulmonary masses were identified. Forty-five patients with peripheral pulmonary masses were examined. Enhancement was evaluated by means of optical density values measured on trispiral tomograms of the lung masses before and after bolus injection of contrast medium. Results suggest that contrast enhancement of pulmonary masses can be measured on sectional images and that this may become a feasible diagnostic method in the detection of lung cancer. CT offers a simplified technique that is now being explored by the authors.

Illusory consolidation of the left lower lobe: a pitfall of portable radiography.

The definition of the left hemidiaphragm is frequently lost when patients are evaluated with portable radiographic equipment. Experimental evidence, based on results of radiography and subsequent sagittal sectioning of a frozen, unembalmed human thorax, corroborated the authors' hypothesis that this finding is related to loss of tangential imaging of the apex of the hemidiaphragm due to cephalic angulation of the central beam accompanied by projection of extrapleural fat onto the base of the left lung. In eight of ten patients in whom portable radiography was performed in 10 degrees-15 degrees of lordosis, varying degrees of loss of definition of the left hemidiaphragm were seen, in the absence of disease. This potential pitfall can be avoided by ensuring that the central beam is tangent to the hemidiaphragm. To do otherwise can create the false impression of disease in the left lower lobe, pleural space, or both.

Emergency room radiology. Profile of a typical facility and preliminary report on a dedicated system.

According to a questionnaire survey of emergency room satellite radiologic units in US hospitals, the criteria for optimal radiologic service to seriously ill and injured patients seen in hospital emergency areas are not being satisfied. The survey identifies the salient characteristics of this growing sector of radiologic practice and points to the need for a dedicated emergency room roentgenographic system.

Temporal bone: comparison of pluridirectional tomography and high resolution computed tomography.

The recent introduction of high resolution computed tomography (CT) capable of resolving delicate bony structures such as the temporal bone marks another significant advance in diagnostic imaging. This study was designed to compare the integrity of these new CT images, standard CT images, and conventional complex motion tomographic images against contact radiographs of sliced anatomic specimens. Temporal bones of three frozen cadaver heads were studied with complex motion tomograms at 1 mm intervals and contiguous CT scans at 1.5 mm intervals in axial, coronal, and sagittal projections. The heads were physically sectioned at 2 mm intervals in planes corresponding to the radiographic planes using a precise indexing and sawing system. The tomographic images were compared for information content to contact radiographs of the anatomic specimen sections. Conventional tomographic images and expanded number range target reconstruction CT images proved to be highly accurate. Standard CT reconstruction images were not. The probable clinical effectiveness of each method is discussed.

Linear vs. pluridirectional tomography of the chest: correlative radiographic anatomic study.

The basic imaging capabilities of 15 degrees linear, 30 degrees linear, hypocycloidal, and trispiral tomographic movements were compared using a fresh frozen human cadaver. Large numbers of tomograms, 100 with each tomographic movement, were compared as a motion study developed by copying the four tomographic series on movie film. In addition, the integrity of the tomograms was compared with radiographs of representative 2 mm coronal sections sawed from the fresh frozen thorax specimen. The study demonstrated the theoretical conclusion that a linear tomogram is not a sectional image and does not truthfully represent the planar anatomy of the intended layer. The pluridirectional tomograms, on the other hand, do accurately depict the anatomic section. The more general use of pluridirectional tomographic techniques in the chest is encouraged and should be used as the basis for comparing conventional tomographic imaging capabilities to other new modalities, particularly computed tomography.

Radiation protection of the lens for patients and users.

The problem of radiation-induced cataract development in the lenses of patients and users exposed to diagnostic-quality radiation is reviewed. A cataractogenic dose appears to be about 200 rads from a single exposure and up to 750 rads in protracted doses. Routine use of new protective glasses developed by the authors is recommended for patients. For users, any of the commercially available high lead-content glasses will reduce doses to safe levels. About 70% reduction of dose is afforded by the new photochromic sunglasses.