No abstract

Using both contrast detail and receiver operating characteristic (ROC) evaluation tests, we evaluated different quality images, produced with different film-screen combinations. ROC curves were obtained for six observers who were attempting to detect lung nodules and pulmonary infiltrates. The contrast detail curves were obtained from images of regular circular test patterns of differing contrast, which had been presented to the observers. Our results indicate that contrast detail tests can be used for relative ranking of image systems prior to detailed ROC testing.

No abstract

A survey was conducted to determine the radiopharmaceuticals and radionuclide imaging methods used for thyroid studies in the U.S. in 1981. The final sample, made up of 299 hospitals, was taken from a random sample consisting of 10% (337) of U.S. hospitals performing nuclear medicine studies. The survey showed that over one half of thyroid scans were obtained with Tc-99m pertechnetate and over one half of uptake studies were performed with I-131. Uptake determinations accompanied 78% of scans. Only 8% of the uptake studies were performed without scans. I-123 was more commonly used on the west coast and in the northeast, and there was interest in a more readily available and less expensive supply of I-123. Thyroid studies accounted for 6.7% of all nuclear imaging procedures. Approximately 7,760,000 nuclear medicine imaging procedures were performed in the U.S. in 1981.

No abstract

A series of experiments was performed to investigate differing predictions from the spatial mapping hypothesis of hippocampal function proposed by O'Keefe and Nadel (1978) and the working memory hypothesis proposed more recently by Olton and his colleagues (Olton, Becker, & Handelmann, 1979). Each of two groups of rats was trained to use a different strategy to locate a submerged platform in a tank of opaque water. The MAP group used a spatial mapping strategy to reach a platform in a fixed location over trials; whereas the CUE group used a guidance strategy, which involved following a cue that signaled the location of a randomly placed platform on each trial. Following acquisition, one-half of each group was given low-level unilateral electrical stimulation of the dentate gyrus and immediately tested on the water maze task. The results of Experiment 1 showed that both the MAP and CUE groups were impaired by stimulation. However, it was observed that there was an inadvertent spatial element involved in the CUE task. When this element was eliminated in Experiment 3, the same CUE animals were not affected by a second series of stimulation trials, whereas the MAP animals continued to show impairment. These results are interpreted as strongly supporting the cognitive mapping hypothesis, while at the same time providing little support for the working memory hypothesis of hippocampal function.

No abstract

We report an unusual radiographic appearance of small bowel submucosal edema produced by obstruction from metastatic colorectal carcinoma. The distinctive muscosal pattern of raised polygonal plaques is the same mosaic pattern described in the colon and referred to as "urticaria." This mosaic pattern in the small bowel has not previously been reported.