Biomedical subjects
Publications and source records attributed to C E Ravin.
The position of an armored endotracheal tube was misinterpreted on radiographs. This occurred because no one recognized that there was no radiopaque line extending to the tip of the catheter. Physicians should be aware of this possible pitfall, and manufacturers should remedy the situation by marking such lines on these tubes.
To assess whether it is possible to distinguish benign from malignant solitary pulmonary nodules with digital techniques, a retrospective study of 68 patients with proved solitary nodules was performed. The conventional chest radiograph for each patient was digitized to 2,048 X 2,048 X 12 bits, and changes in the optical density within the nodule were analyzed. A number (the corrected gradient number) was then generated that reflected this variation. Striking differences were noted between 26 malignant nodules and 21 calcified granulomas. The technique was then applied to 21 benign nodules that had initially required thoracotomy or further study for diagnosis. In nine of these 21 patients (43%), the corrected gradient number allowed correct classification as a benign lesion.
We report a unique presentation of spontaneous esophageal perforation or Boerhaave's syndrome. Our patient had no risk factors predisposing her to barogenic rupture of the esophagus, and she had none of the "classic" presenting signs. She was asymptomatic, and her clinical course appeared to be chronic. Her chest roentgenogram demonstrated bilateral thick-walled cavities with air-fluid levels. Computerized axial tomography of the chest and swallow of meglumine diatrizoate (Gastrografin) showed the cavities and esophagus to communicate. This patient's presentation and radiographic studies extend the reported description of Boerhaave's syndrome.
Calcification overlying the left side of the heart on a chest radiograph may involve either the pericardium or, alternatively, the myocardium in association with a left ventricular aneurysm. Distinction between these two conditions can be of great clinical significance. To identify distinguishing features, we reviewed the radiographs and medical records of 29 patients: 14 had proven calcific pericarditis and 15 had proven calcified left ventricular aneurysm. Pericardial calcification was found primarily over the right-sided cardiac chambers (14 of 14 patients) and in the atrioventricular grooves (11 of 14), infrequently over the base of the left ventricle (five of 14), and rarely over the apex of the left ventricle (two of 14). When the left ventricle was involved, there was always more extensive calcification elsewhere in the pericardium. Myocardial calcification occurred predominantly in the apex of the left ventricle (13 of 15 patients), although it was rarely confined to the posterior wall of the left ventricle (two of 15). By noting characteristic sites of calcium deposition, pericardial calcification can be effectively distinguished from myocardial calcification. Isolated calcification in the region of the left ventricular apex, therefore, strongly suggests left ventricular aneurysm.
Recognizing pneumothorax and hydropneumothorax on chest x-rays of supine ICU patients requires attention to areas other than the lung apex. Pleural air in a supine patient collects in the anterior costophrenic sulcus, producing hyperlucency over the upper abdominal quadrants, and the deep costophrenic sulcus sign. Hydropneumothorax may be recognized when a sharp pleural line is bordered by increased opacity within the pleural space. The presence of pneumothorax and hydropneumothorax can be confirmed by decubitus or upright chest x-rays.
One of the potential advantages of digital chest imaging is the ability to process these images. However, such processing, when uniformly applied to the entire image, is often unsatisfactory due to the different processing requirements of lung field and mediastinum. Therefore, a method to selectively process these regions based upon the histogram of the original image has been developed. Thirteen conventional chest films were digitized with a laser film scanner. Analysis of individual lung field and mediastinum histograms showed that the chest image histogram is essentially bimodal with significant lung field-mediastinum histogram peak separation; overlap between these peaks is small (9% of the total histogram) and insensitive to minor pathologic change or radiographic technique. Using these histograms, a gray level threshold distinguishing mediastinum from lung field was selected and used to direct the regionally-selective processing of several chest images. This technique may prove especially useful for digital enhancement of the underexposed mediastinum often encountered on conventional chest radiographs.
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Radiology is valuable in determining the cause of pacemaker malfunction and in the evaluation of lead position and integrity.
The bronchial supply of the lateral or axillary area of the right upper lobe is variable. In 16 percent of normal subjects, an independent ramus of the posterior right upper lobe bronchus supplies an axillary subsegment. Airspace disease in the axillary subsegment has a characteristic appearance on radiographs. The CT appearance of disease in the axillary subsegment correlates closely with classic anatomic studies. Recognizing that disease is located in the axillary subsegment can help in directing bronchoscopy or biopsy.
An accurate diagnosis of pulmonary embolism is essential to prevent excessive morbidity and mortality from lack of therapy or inappropriate anticoagulation. Clinical signs and symptoms are reported to be nonspecific, although published studies do not allow calculation of true specificity. Since certain clinical characteristics or groups of findings may be sensitive enough for pulmonary embolism, the diagnosis is unlikely in their absence. Ventilation-perfusion lung scanning has high sensitivity but variable specificity for pulmonary embolism. Patients with scans showing multiple segmental or lobar perfusion defects with normal ventilation have a high probability of pulmonary embolism. Scans with less extensive perfusion abnormalities or matching ventilation defects do not reliably exclude pulmonary embolism. Pulmonary angiography is the most definitive procedure for diagnosing pulmonary embolism. Digital subtraction pulmonary angiography and radiolabeled platelet scanning are promising but require more extensive validation before routine use.
To determine the effect of clinical assessments and lung scan results on the management of patients, we studied 566 consecutive patients referred for lung scans because of suspected pulmonary embolism. Prior to the lung scan, the clinician was asked to estimate the probability of pulmonary embolus. Two or three days later the physician was contacted to determine how the patient was managed. The results of the lung scan strongly influenced patient management. Patients with high probability lung scans were treated for pulmonary embolism regardless of the clinical pretest estimate. Low and intermediate probability lung scans resulted in most patients not being treated for pulmonary embolism and not referred for pulmonary angiography. Only 55 of the 566 patients were referred for pulmonary angiography, and approximately one-half of these patients had lung scans with an intermediate probability for pulmonary embolism.
Studies evaluating observer accuracy and visual perception of pulmonary nodules usually are based upon test films obtained from clinical practice in patients with proven pulmonary nodules. Unfortunately, such nodules do not always occur in the optimal size and location to facilitate testing. Such studies would be enhanced by the ability to place nodules of desired size and location on chest radiographs. This report describes a method of placing a computer-generated (synthesized) nodule on a digitized chest radiograph. To demonstrate the similarity of these synthesized nodules to real nodules, each digitized radiograph with a computer-generated nodule was paired with a digitized chest radiograph of a patient with a clinically proven pulmonary nodule. A total of 22 pairs of chest radiographs were then shown to 13 radiologists, who were asked to distinguish the synthesized nodule from the real nodule. With this two alternative forced-choice test, the radiologists were only able to distinguish the synthesized nodule in 51% of the cases, strongly suggesting that computer generated nodules may be used to simulate real pulmonary nodules in future tests of nodule detection.
Transvenous pacing accomplished from the right atrial appendage, either alone or in combination with right ventricular pacing, is becoming increasingly popular for selected patients in whom the contribution of atrial systole is advantageous. On the frontal chest radiograph, the pacemaker is seen to terminate over the right upper heart border, often seeming to turn abruptly cephalad. On the lateral radiograph, the lead follows a smooth, smooth, anterior curve in the midportion of the heart with its tip angled cephalad into the right atrial appendage. Complications associated with the use of this form of transvenous pacing are similar to those seen with other transvenous pacemakers; in addition, the catheter may be positioned inadvertently in the body of the right atrium, resulting in less effective atrial pacing.
On the basis of autopsy series, the incidence of direct cardiac involvement in sarcoidosis has been estimated to be 20%-27%. It may be recognized clinically when patients with known systemic sarcoidosis present with arrhythmias, conduction disturbances, or cardiomyopathy. Various radiographic manifestations of cardiac sarcoid, including cardiomegaly, pericardial effusion, and left ventricular aneurysm, are described in four patients.
The likelihood of metastatic spread of an extrathoracic primary tumor to the thorax depends on a number of factors, most importantly, the site and nature of the primary tumor. Although the plain chest radiography remains the first-line screening procedure, understanding the pattern of spread of various tumors and the frequency with which such spread occurs enables one to develop a rational approach to the use of other imaging modalities, particularly computed tomography, in evaluation of patients with known extrathoracic primary tumors.
Radiographic imaging of the chest remains one of the most important and most challenging problems in radiology. The wide range of information that results from the great variation of radiation behind the lungs compared with that behind the mediastinum creates a very difficult imaging problem. The introduction and continued investigation of digital techniques have presented a potential solution to this problem. In this article, the authors describe the image-processing techniques of histogram equalization and adaptive filtration in digital chest imaging.
We have presented four cases of bronchogenic cyst, emphasizing the uncommon radiologic manifestations, including air trapping and/or lobulated contour. Two of the cysts were in the lung parenchyma, one in the left hilum adherent to the left lower lobe bronchus, and one in the posterior mediastinum. Recognition of the unusual radiologic features aids in establishing an appropriate differential diagnosis and directing subsequent evaluation.
Forty patients with coarctation of the aorta were compared with 80 normal subjects matched by sex and age. The aortic arch was invisible on the lateral radiograph in 84% of patients preoperatively and 88% postoperatively. Only 6 normal subjects (8%) had a similar finding. The authors conclude that an obscured aortic arch on the lateral view could be a clue to the presence of coarctation. Possible explanations for this phenomenon include (a) dilatation of the brachiocephalic arteries (particularly the left subclavian artery), obscuring the superior margin of the arch; (b) hypoplasia and anteromedial displacement of the distal portion of the arch; and (c) diffuse hypoplasia of the arch combined with focal coarctation.