Contrast Enhancement with Television Technics: Gallbladder Lesions

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Abstract
Television technics for contrast enhancement and color translation of roentgenograms were recently described (1, 2), and the possibilities of these technics for daily use in roentgenography were indicated. The present report is concerned with a practical application of the procedure. In spite of the accuracy of cholecystography, minute stones and papillomata are often difficult to demonstrate because of the small contrast differences. The television system of scanning x-ray films with the Exicon3 achieves contrast enhancement of approximately twenty-fold. Discernment of small gallstones or wall-bound papillomata whose presence otherwise would not be appreciated, or at best only suspected, is accomplished quickly and directly by viewing monochrome and color television monitors of the scanned x-ray film. An illustrative example probably better conveys the range of these conversions. Example I is a cholecystogram of a 50-year-old woman who had recurring attacks of pain in the right upper quadrant for seven years. She also had an attack of jaundice lasting several weeks, one year preceding the recent onset of pain in the gallbladder area. Cholecystograms made in various positions revealed a barely visible defect in the shadow of the gallbladder suspected of being due to an adherent cholesterin stone or adenoma (Fig. 1). When this film is viewed in the Exicon, contrast enhancement makes possible the clear discernment of the small filling defect on the gallbladder wall (Fig. 2). Viewed on the color monitor, the defect shows up in green projecting from the gallbladder wall into the red opaque medium, Fig. 3. A small adenoma was found by the pathologist in this case. Discussion Figures 2 and 3 in this report were photographed directly from the monochrome and color television monitors and have necessarily lost something in the process of photographic reproduction. Also not conveyed are the many intermediate steps of contrast enhancement and color translation which are rapidly obtained merely by turns of the controls. These intermediate steps give the viewer the impression of looking at a series of planigraphic films. Instead of looking at different planes of anatomy, one is confronted with color changes which are based on varying photographic densities. Anatomical orientation is always maintained, however, by simultaneous viewing of the monochrome monitor. As a matter of fact, suppression of noncontributory images in the televised conversions greatly increases the detection of anatomical detail. In Figure 2 all shadows around the gallbladder are seen to be completely suppressed. Comparison of contrast enhancement by television technic might be made with that of LogEtronics (3), a method of photographic reproduction with contrast enhancement.

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