Simplifying radiological examinations. The urogram as a model.

The diagnostic yield of one and three film urograms was compared with that of complete examinations to determine whether a moderately complex examination could be simplified without loss of important diagnostic information. Although sensitivity was high (88-93%) and was not altered by increasing the complexity of the examination, the definitive disease diagnoses were more accurate with the three film rather than the one film studies. Specificity increased from 69% to 77-80% with the more complex examinations. A strategy based on terminating the examination if the single film urogram is normal with a three-film examination in positive cases might effect considerable savings, both economic and in terms of gonadal radiation dose, without serious diagnostic loss.

The barium enema; evidence for proper utilization.

A group of 1,041 patients was studied in an attempt to identify symptoms, signs, or laboratory findings (disease indicators) associated with either a high or low yield of abnormal barium enemas. A specific search was undertaken for subgroups with one or more statistically significant indicators of large bowel disease. If enemas were performed only for statistically significant indicators (fever, positive stool benzidine, rectal or abdominal mass, low hematocrit) or indicators of clinical importance (weight loss, constipation, diarrhea, etc.) only 13% of examinations would be eliminated. At the same time, however, 10% of patients with gastrointestinal disease would be missed.

Computed tomography of the brain in patients with headache or temporal lobe epilepsy: findings and cost-effectiveness.

Computed tomographic (CT) examinations of the brain were reviewed in 85 patients with a chief complaint of headache and in 22 patients with temporal lobe epilepsy in an attempt to assess the yield and cost-effectiveness in these two clinical settings. Lower bounds for the costs of case finding were calculated using probabilistic estimates. In patients with headache and no objective neurologic findings, no abnormal CT examinations were found. On the other hand, 34% of patients with headache and associated objective neurologic findings had abnormal CT studies. No abnormal CT examinations occurred in patients with temporal lobe epilepsy. The calculated lower bounds for the costs of case finding for these groups were $4,363, $500, and $1,846 per patient, respectively.

The value of consultation among radiologists.

The value of group consultation in improving the accuracy of radiologic diagnosis was assessed. Abnormalities on 24 films were pointed out to six groups of three radiologists each. They were asked to reach a specific diagnosis for each case. Accuracy was compared in three settingss: (1) without consultation; (2) with consultation leading to a diagnosis by group consensus; and (3) with consultation followed by independent diagnoses. The accuracy of over 75% of the radiologist improved after consultation in either setting. The extent of improvement was inversely related to the initial accuracy level of the individual. When two or three radiologists agreed initially, they were more frequently correct than not. Group discussion followed by individual diagnosis is a practical approach to radiologic consultation.

Intrathoracic stomach: when does it obstruct?

Large esophageal and paraesophageal gastric herniations may occasionally produce gastric obstruction and strangulation. Seven cases of gastric intrathoracic herniation of varying degree, including 2 with obstruction, are presented with diagrams of the anatomy in each case. The cases with obstruction are discussed in relation to existing theories of the mechanism of obstruction: (a) tightness of the hernial ring; (b) acute volvulis of the herniated stomach; and (c) subdiaphragmatic redescent of the fundus with fundic distension and crowding of the hernial orifice. It is concluded that the last mechanism is the most common, but that a combination of mechanisms produces the obstruction in some cases.

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.

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.