RETRACTED: Differing attenuation coefficients of normal and infarcted myocardium.

There are significant differences in attenuation coefficients between normal and infarcted myocardium measurable with a computerized transaxial tomographic scanner. Additionally, iodinated contrast material administered prior to killing the tests animals resulted in excellent visualization of the blood-myocardial interface at a time when standard radiographs detected no differences between the ventricular cavity and the myocardial wall. These natural and induced changes in attenuation coefficients offer a new approach to evaluating and understanding the processes of tissue injury and death. Their clinical relevance lies in application to the twin problems of myocardial infarction and the structure and function of the cardiac wall.

Measures of clinical efficacy. III. The value of the lung scan in the evaluation of young patients with pleuritic chest pain.

The usefulness of various modalities in evaluating pleuritic pain in young patients and in isolating cases of pulmonary embolism was assessed using likelihood ratios and the receiver operating characteristic (ROC) curve. History and physical, laboratory, and radiographic finding were used disjunctively to establish an ROC curve. The percentage of patients found to have pulmonary embolism increased monotonically with certain critical pieces of diagnostic data. For example, a history and physical examination alone detected 80% of patients with pulmonary embolism; a chest radiograph raised the percentage to 95%; and the addition of a lung scan increased the percentage to 100%. Thus, with proper interpretation of clinical and radiographic data, the lung scan has only a marginal impact upon the sensitivity with which pulmonary embolism is detected. Its major value is an increased specificity in the diagnosis of pulmonary embolism.

Disagreements in chest roentgen interpretation.

Each of 100 chest radiographs selected randomly from a hospital population were read by five experienced radiologists. The films were rich in abnormal findings. Disagreement analysis was performed considering the entire content of the interpretation. The disagreements were graded by a panel as to type (false negative, false positive, and indeterminate) and significance. The overall repeatability of the panel's performance was 75 percent. Forty-one percent of the reports contained potentially significant errors and 56 percent indeterminate disagreements. Among all errors 78 percent were false negatives and 22 percent were false positives. The error rate varied among readers. An average of 25 percent of important findings were omitted by an individual reader. An association between specific abnormalities and the types of disagreement was found.

Accuracy and its relationship to experience in the interpretation of chest radiographs.

One hundred chest radiographs, randomly selected from a hospital population, were read by 8 radiologists at 4 different levels of training and experience. All statements in the 800 interpretations were analyzed for accuracy. The analysis was based on deviation from a "true" report. Approximately 26% of significant and potentially significant statements were errors. Eighty per cent of these were false negative, 20% false positive. While significant individual differences in interpretive accuracy were found, there was no consistent pattern related to the duration of training beyond the first year of residency. Once an individual's radiologic education has progressed beyond a fundamental level, individual reader characteristics overshadow experience in the accuracy of chest film interpretation.

The value of searching films without specific preconceptions.

The detection of simulated pulmonary nodules was measured in three different situations that required: (1) reports of all significant chest findings (Free Search), (2) only reports of possible nodules (Nodule Search), or (3) evaluation of particular film locations as nodules (Specified Location). ROC curves from these conditions compared how accurately readers could distinguish between the nodule and normal "test locations," and between the films that did and did not contain nodules. In replication of previous results for heterogeneous chest findings, detection accuracy was superior when readers had to search the films. Each reader's distinctions between the nodule and normal test locations became considerably less accurate when these locations were prespecified for explicit evaluation. When asked to search only for pulmonary nodules, most readers substantially increased their false reports of nodules at each level of confidence, with little improvement in their (already high) true-detection rates. Searching for nodules increased both the true-detection and false-detection rates for two readers, who simply appeared to relax a strong bias against reporting nodules in the initial Free-Search situation.

Radiographic interpretation with and without search: visual search aids the recognition of chest pathology.

Radiologists could distinguish between the normal and abnormal radiographic features in a specific test set much better when searching chest radiographs for any abnormal findings than when explicitly evaluating each individual test feature without searching the films. Because the radiologists' ability to separate the subtle test abnormalities from normal variations was severely reduced by directing attention to these particular radiographic features, the recognition of abnormal findings may have been augmented by perceptual mechanisms that functioned only during the process of visual search. These could be visual mechanisms, developed through experience in scanning familiar examinations, that detect "unusual" pattern configurations and automatically draw the radiologist's attention to features that are likely to represent pathology.

The radiologic assessment of vessel wall thickness.

A method allowing accurate and repeated measurements of vessel wall thickness has been developed. It consists of permanent opacification of the outer wall with tantalum in conjunction with magnification angiography. The technique was tested in a model, in human saphenous vein specimens, and in long-term experiments in rabbit blood vessels. Eighteen rabbits underwent exploratory surgery, after which the abdominal aorta, inferior vena cave, and the femoral and carotid arteries were coated with tantalum paste. Subsequently, magnification angiograms were performed from one to 14 months later. The wall thickness ranging between 100 and 300 micron was clearly visualized. While no gross inflammatory or foreign body reaction was seen, small granulomata adjacent to the blood vessels were frequently identified. The method described can be valuable in studying the natural history of the atherosclerotic process, particularly the behavior of vascular grafts.

The composition of the radiologic report.

In order to understand and evaluate fully the composition of the radiologic report, an experiment was performed in which eight readers each read the same 100 chest radiographs. The reports were dissected into individual statements, each of which was analyzed for accuracy, statement type (descriptive or etiologic), confidence, and specificity. In addition, each report was evaluated for stylistic factors of succinctness, orderliness, and the use of supplemental comments. Detailed analysis showed the radiologic report to be a series of largely descriptive statements in which confidence level, specificity, and orderliness were associated with the presence of errors in film interpretation. These factors can serve as important markers for identifying error-laden films. The use of specific, etiologic diagnoses in these film readings was limited. The composition of the report was not related to the length of radiologic training beyond the first year of residency. The implications of these findings concerning report composition in light of present day radiologic practice and new, automated radiologic reporting systems were discussed.

Improving diagnostic accuracy: a comparison of interactive and Delphi consultations.

Consultation among physicians on difficult diagnostic problems is commonly used to improve the accuracy of medical decisions. Such consultation is most often informal and interactive. Nevertheless, behavioral studies suggest that non-interactive techniques may be more effective problem solving methods. Of these the Delphi approach, involving pooling and feedback of anonymously contributed information, has generated particular interest. To assess the relative effectiveness of independent decision making, interactive group consultation, and Delphi techniques in a clinical setting we compared the diagnostic accuracy of 17 radiologists interpreting radiologic examinations in these settings. Interactive consultation improved performance by 69% compared to radiologists interpreting the studies individually. In addition, two Delphi strategies each produced an additional 20% mean improvement in accuracy over interactive consultation. Whereas interactive consultation improved the accuracy of the best individual readers by only 6%, a Delphi model improved their performance by 25%. Thus, Delphi was an effective, easily applied method of clinical consultation whose usefulness in other clinical setting should be evaluated.

Renal collateral blood supply after acute unilateral renal artery occlusion.

Preformed arterial collaterals are critical to renal parenchymal survival after acute total renal artery occlusion. This study was designed to delineate and quantify preformed collaterals and assess their response to vasodilators. A Swan-Ganz catheter induced a sudden, total occlusion of a renal artery sufficient to reduce distal arterial pressure to near zero and prevent perfusion through the renal artery. Arteriography assessed the effectiveness of the occlusion and delineated the collateral arterial pathways. Strontium, cerium-, and chromium-labeled microspheres measured renal blood flow and cardiac output 1, 60, and 120 minutes after occlusion. In two additional series of experiments either contralateral nephrectomy was performed 5 to 8 days before the study, or dibenzylene, dopamine, or glucagon were administered in an attempt to increase blood flow through the collaterals. Collateral renal blood flow was demonstrated in all dogs. Mean blood flow to the occluded kidneys ranged from 0.13 +/- 0.05 cm3/minute/g to 0.22 +/- 0.08 cm3/minute/g, about 5% of control values. Neither prior contralateral nephrectomy nor vasodilator agents increased the flow to the obstructed kidneys. In the dogs with intact contralateral kidneys, however, there was a progressive decrease in cardiac output during the experiment, which was not found in uninephrectomized animals. We concluded that preformed arterial channels are available to maintain a small, but probably critical level of perfusion following sudden total occlusion of the renal artery. Neither hypertrophy due to prior contralateral nephrectomy nor active vasodilators modify flow through the preformed channels. It is likely that total renal ischemia provides a maximal stimulus for vasodilatation. The pattern of hind limb collaterals differed strikingly from those of the kidney, with maintenance of a greater portion of a normal flow and rapid increase in flow within 1 hour after femoral artery occlusion. Thus, data concerning collateral circulation cannot be generalized from one vascular bed to another even in the same species.

Digital subtraction angiography in the community hospital.

Although digital angiography may involve the same physician processes in the university as in the community hospital, it can be seen that the indications, approaches, and utility of DSA are somewhat different in the two environments. DSA is presently in a state of change, in part because of the maturing of other modalities and also because of the present emphasis on cost-saving in medical imaging. As referring physicians become used to digital arteriographic images, more and more procedures will be performed with DSA. We believe the DSA will have an important role in the community hospital for years to come. Its emergence as the first of the "conventional" imaging techniques to be digitized can be seen as an initial step toward the total digital imaging department of the future.

The diagnostic accuracy and complications of closed lung biopsies.

The diagnostic yields and complication rates of closed lung biopsies were determined by responses to a questionnaire. Of 5,255 procedures reported, 30% were aspiration biopsies (AB), 7% tissue core biopsies (CB), 2% trephine biopsies (TR), 37% bronchial brush biopsies (BB), and 23% transbronchial biopsies (TB). Of these biopsies, 70% were done for suspected neoplasms. The diagnostic accuracy rates were: AB=82%, CB=84%, TR=86%, BB=61%, and TB=56%. Mortality rates were: AB=0.1%, CB=0.3%, TR=2.9%, BB=0.0%, and TB=0.3%. Transthoracic needle biopsies (AB, CB) had the highest overall diagnostic accuracy, with an associated low mortality and moderate morbidity.

Femoral artery catheterization and vessel tortuosity.

In the era of selective and superselective arteriography, vessel tortuosity, even in the presence of good pulses, can impede catheterization of the aorta and its branches. We assessed 101 patients who had femoral arteriography to determine whether there was a significant difference in tortuosity between the right and left sides and to define the degree to which significant tortuosity was bilateral. Fourteen and 21 patients had tortuosity greater than 1 standard deviation above the mean of the population on the right and left sides, respectively. This difference was not statistically significant. Twenty-three of the 29 patients with tortuosity greater than 1 standard deviation above the mean had this finding unilaterally. There is no advantage to preferentially beginning catheterization on a particular side. Furthermore, since 80% of significant tortuosity is unilateral, the contralateral femoral artery should be approached with only minimal delay when tortuosity that impedes catheterization is encountered.

CT of the pancreatic tail.

The location of the pancreatic tail varies and is confined only by the limits of the anterior pararenal space and the left kidney. The morphology of the pancreatic tail and its location relative to the upper pole of the left kidney, the body of the pancreas, and the splenic hilum were assessed by body computed tomography in 101 patients with normal kidneys and in 15 patients with either small or absent left kidneys. In 97% of normal patients, the pancreatic tail was located anterior or anterolateral to the left kidney. In 75% of patients with surgically or congenitally absent kidneys, the pancreatic tail lay dorsomedial, adjacent to the spine, and occupied, with bowel and spleen, the empty renal fossa. Variation in pancreatic tail location may be of diagnostic importance in patients suspected of having mass lesions in the left mid-abdomen.

Computed tomography in the diagnosis and management of paravertebral masses.

The role of computed tomography (CT) in the detection, evaluation, and management of paravertebral masses was studied in 32 consecutive patients with such lesions. The characteristics of the patients and masses were tabulated, and follow-up data were collected. There were 25 neoplasms (of which 24 were malignant), 5 inflammatory lesions, and two cases without proven diagnosis. The CT provided unique diagnostic information in 9 of the 32 cases (28%), and information that affected patient management in 13 cases (41%). Overall, CT proved of benefit in 19 of the 32 patients (59%). These findings indicate that CT can make important contributions to the diagnosis and management of paravertebral masses.