Detection and estimation of the volume of pneumothorax using real-time sonography: efficacy determined by receiver operating characteristic analysis.

OBJECTIVE: The purpose of this study was to determine the efficacy of real-time sonography for the detection and estimation of the volume of pneumothorax using receiver operating characteristic (ROC) analysis in 27 patients evaluated by five radiologists using previously described sonographic findings. MATERIALS AND METHODS: Bilateral chest sonograms were obtained in 27 patients after we performed 26 needle biopsies of the lung and two transcostal biopsies of lesions at the dome of the liver. Thirteen unilateral pneumothoraces were found on radiographs done at the time of the sonograms. The sonograms were recorded on videotape and later viewed by five blinded readers who scored each hemithorax independently as to the likelihood and size of pneumothorax. From these interpretations we were able to calculate ROC curves and standard accuracy statistics for each observer and for pooled data. The results were correlated with the findings on chest radiographs, which were used to verify the diagnoses. RESULTS: The area under the ROC curves ranged from 0.63 to 0.79 in detecting any pneumothorax. The area under the ROC curve derived by pooling readers and hemithoraces using the jackknife method was 0.73. The average sensitivity of the five observers fro pneumothorax was 73%, the specificity was 68%, and the negative and positive predictive values were 89% and 40%, respectively. No significant correlation was found between readers' estimates of pneumothorax size made on the basis of sonographic findings and actual size as ascertained from chest radiographs. CONCLUSION: Real time sonography is useful to localize known pneumothorax but cannot be used to exclude the diagnosis. Moreover, sonography has a significant false-positive rate and is of no use in estimating the volume of a pneumothorax.

Reversal of flow in the inferior epigastric arteries: Doppler ultrasonographic findings and significance.

The objective of this work is to evaluate the significance of finding reversal of flow in the inferior epigastric artery during noninvasive assessment of the lower extremity circulation using Doppler ultrasonography. This phenomenon is easy to demonstrate when present and predicts aortic or iliac artery stenosis or occlusion at subsequent arteriography. We found collateralization to the leg from the ipsilateral internal mammary artery via the epigastric arteries in all cases in which ultrasonography showed such reversal and these vessels carried the majority of the blood supply to the leg. This finding and its significance should be conveyed to patients and their physicians so that deliberate harvesting or inadvertent surgical damage to the epigastric arteries can be avoided, as this has been shown to lead to worsening of leg ischemia.

Fatal reactions to intravenous nonionic contrast material.

Three cases of fatality related to the use of low-osmolality contrast material (LOCM) are presented. LOCM definitely reduces unpleasant side effects and serious reactions, but data are currently insufficient to determine whether the death rate is any different from that associated with high-osmolality contrast agents. If the present trend toward universal conversion to LOCM continues, an enormous cost for little, if any, lifesaving benefit may be incurred.

Effects of corticosterone on the electrophysiology of hippocampal CA1 pyramidal cells in vitro.

Modulation of CA1 field potential amplitudes by normal and stress concentrations of corticosterone (CT) was observed in hippocampal slice preparations from adrenalectomized rats. Slices exposed to CT levels characteristic of a morning (4 nM) or evening (7 nM) resting state showed increased population spike amplitudes in the CA1 pyramidal cell field within 10 min. A stress concentration (15 nM) also increased spike amplitudes, but only at the higher stimulus intensities. The effects of these doses were essentially the same 10 and 60 min after administration. The hormone facilitated responding more in morning resting concentrations than in concentrations characteristic of the evening resting state. This occurred, however, only for relatively low intensity stimuli. The data provide some support for the suggestion that circadian fluctuations in magnitude of long-term potentiation result from corresponding changes in CT level. The rapid onset of the observed changes is difficult to account for in terms of generally accepted mechanisms of receptor binding.

The origin of the hippocampal commissure in the rat.

The present study was designated to determine the origin of commissural axons in the hippocampus. One hippocampus of 94 rats was pressure injected with 40% horseradish peroxidase (Sigma VI), or with 2-4% wheat germ agglutinin HRP (E-Y Labs). Injections (0.001 to 0.1 microliter) were made through glass micropipettes with fitted plungers. Pipettes were positioned stereotaxically, and by electrophysiological monitoring through the injection syringe. An ipsilateral stimulating electrode activated CA3 and CA1 cells via Schaffer collaterals. Population potentials were monitored as the recording pipette was advanced from the cortical surface into the hippocampus. Wave forms of monosynaptically elicited field potentials provided an accurate indicator of its position. Following survival periods of 24 hours, the brains were processed according to the Mesulam method. Forty-micron sections were serially mounted and counterstained. Injection sites and filled cells were plotted manually on a standard set of coronal sections. Our results indicate that field CA1 receives input from contralateral subfields CA1a and c, as well as from all CA3 subfields. In addition, rostral CA1 injections resulted in labeling of cells in the contralateral subiculum and entorhinal cortex. Homotopic connections exist between subfields CA3a and b; it appears that a major input to CA3c is from the contralateral polymorph cells of the dentate hilus. Commissural input to the dentate granule cells appears to be the giant polymorph and CA3c cells of the contralateral dentate hilus. With respect to the question of homotopicity, our results suggest that commissural connections are predominantly homotopic in the mediolateral plane, although CA1 and CA3 injections also resulted in contralateral labeling of hippocampal cells caudal to the levels of injection.