Robert D. Tarver

Reexpansion pulmonary edema

Reexpansion pulmonary edema is a rare complication attending the rapid reexpansion of a chronically collapsed lung, such as occurs after evacuation of a large amount of air or fluid from the pleural space. The condition usually appears unexpectedly and dramatically—immediately or within 1 h in 64% of patients and within 24 h in the remainder. The clinical manifestations are varied; they range from roentgenographic findings alone in asymptomatic patients to severe cardiorespiratory insufficiency. The radiographic evidence of reexpansion pulmonary edema is a unilateral alveolar filling pattern, seen within a few hours of reexpansion of the lung. The edema may progress for 24–48 h and persist for 4–5 days. Human data on the pathophysiology of reexpansion pulmonary edema derive from small series of patients, case reports, and reviews of the literature. On the other hand, a larger body of data exists on experimental reexpansion pulmonary edema in cats, monkeys, rabbits, sheep, and goats. This review examines the clinical and experimental evidence for reexpansion pulmonary edema. In addition, we detail the historical background, clinical setting, treatment, and outcome of reexpansion pulmonary edema.

Distinguishing viable from infarcted myocardium after experimental ischemia and reperfusion by using nuclear magnetic resonance imaging

Early reperfusion has the potential for salvaging ischemic myocardium at risk for infarction. To test the ability of nuclear magnetic resonance (NMR) imaging to differentiate between stunned and infarcted myocardium early after reperfusion, 16 mongrel dogs underwent transient occlusion of the left anterior descending artery or a diagonal branch for 30, 60 or 180 min followed by reperfusion. To identify the area at risk for infarction and to assess the extent of hypoperfusion and reperfusion, two-dimensional and contrast echocardiography were performed at baseline study, during coronary occlusion and at three separate times during reperfusion (before NMR imaging, immediately after NMR imaging and 12 to 14 h later). Wall thickening in the control and ischemic zones and the circumferential extent of abnormal wall motion were analyzed at each time point using short-axis echocardiograms. Nuclear magnetic resonance imaging at 1.5 tesla was performed 2 to 3.5 h (mean 2.7 +/- 0.5) after reperfusion. Short-axis, multislice spin-echo images (TE 26 and TE 60) were obtained. Signal intensity was measured in the control and ischemic areas and expressed as a percent difference compared with normal myocardium. All dogs demonstrated a significant decrease in wall thickening and abnormal wall motion before and after NMR imaging. Seven of the eight dogs with infarction had an area of increased signal intensity on TE 60 images. The mean percent difference in signal intensity compared with adjacent normal myocardium was 127 +/- 68% (p = 0.002). None of the eight dogs without infarction had a visually apparent change in signal intensity on TE 60 images (mean percent difference versus control area 13 +/- 11%), despite regional systolic dysfunction documented by echocardiography at the time of imaging. The area of increased signal intensity correlated with infarct size (r = 0.69), although overestimation by NMR imaging occurred. The area of increased signal intensity did not correlate with the extent of echocardiographic contrast defect during coronary occlusion (risk area). This study demonstrates that NMR imaging can be applied early after coronary reperfusion to assess the potential for recovery of dysfunctional myocardium. In addition, by using a TE 60 multislice spin-echo imaging sequence at 1.5 tesla, quantification of the extent of infarction also may be possible.

Endoscopic transesophageal fine needle aspiration of mediastinal masses

Several techniques are currently in widespread use for obtaining biopsy samples of mediastinal masses. These include fine needle aspiration under CT or fluoroscopic guidance, l bronchoscopic biopsy, transbronchial fine needle aspiration,2. 3 mediastinoscopy, the mini-anterior thoracotomy,4 and standard thoracotomy. However, each technique is limited in that certain areas of the mediastinum are inaccessible for biopsy or because thoracotomy may entail prolonged hospitalization and significant morbidity. In this report we describe nine patients in whom an endoscopic transesophageal approach was successfully employed to obtain diagnostic samples from mediastinal masses. This endoscopic approach, which we have termed endoscopic transesophageal fine needle aspiration (ETFNA), is a variation of previously described endoscopic fine needle aspiration methods which have been successfully used to sample malignancies in the upper gastrointestinal tract and in the rectum. Thus, previous reports have described the successful use of endoscopic fine needle aspiration to sample esophageal and gastric cancers,5. 6 infiltrating gastric cancers,7 and rectal cancers.s Kochhar et a1.s also described successful proctoscopic fine needle aspiration of digitally palpable metastases in the pouch of Douglas or rectovesical pouch.s To our knowledge, however, the present report is the first description of the use of endoscopic fine needle aspiration to sample mediastinal masses extrinsic to the esophagus.

Imaging the diaphragm and its disorders

Although a radiologic evaluation of the diaphragm is important in many clinical situations, visualization of the diaphragm is difficult because of its thinness, its domed contour, and its contiguity with abdominal soft tissues. Each clinical situation involving the diaphragm presents its own imaging difficulties, and each radiographic technique has advantages and disadvantages. No one modality is best for all situations. Often, several imaging modalities must be used to resolve the clinical question. The particular difficulties in diaphragmatic imaging are (1) distinguishing eventration from paralysis or hernia, (2) distinguishing lipoma from herniated omental fat, and (3) distinguishing unilateral paralysis from weakness and bilateral paralysis from respiratory fatigue. By selecting and applying the appropriate radiographic techniques, the radiologist can serve an essential role in assessing the disorders of the diaphragm.

Workers with Libby Amphibole Exposure: Retrospective Identification and Progression of Radiographic Changes

PURPOSE To assess how early pleural and/or parenchymal abnormalities consistent with asbestos exposure could be ascertained and to identify factors associated with progression. MATERIALS AND METHODS Informed consent was obtained under an institutional review board-approved protocol. Multiple sequential chest radiographs obtained between 1955 and 2004 in 84 workers exposed to amphiboles associated with vermiculite in the town of Libby, Montana, were studied. A panel of three NIOSH B readers reviewed each workers longitudinal chest radiograph series in reverse chronologic order and achieved a consensus reading for each radiograph. Measures of exposure were compared between workers with and those without progression of parenchymal and pleural abnormalities. RESULTS Because of the way the study was designed, all subjects had pleural (n = 84) and/or parenchymal (n = 26) abnormalities on the most recent chest radiograph. Compared with other investigations that used different methods, this investigation revealed shorter latency periods (defined as the interval between date of hire and date of earliest radiographic detection) for circumscribed pleural plaque (median latency, 8.6 years) and pleural calcification (median latency, 17.5 years). Pleural abnormalities progressed in 64 workers, while parenchymal abnormalities progressed in 14. No significant differences were found with regard to measures of exposure between workers with and those without progression. CONCLUSION The latency period for the development of pleural plaques may be shorter than previously reported. Early plaques are subtle and may not be detectable except at retrospective review.

The value of good medical student teaching: Increasing the number of radiology residency applicants

RATIONALE AND OBJECTIVES The authors attempted to define the value of good medical student teaching to the profession of radiology by examining the effect of radiology course improvements on the number of 4th-year students applying to radiology residencies. MATERIALS AND METHODS Course evaluation and residency application data were obtained from six consecutive classes of 4th-year medical students at the study institution, and these data were compared with national data. RESULTS Between 1995 and 2000, the number of 4th-year U.S. medical students applying to radiology increased 1.6 times. At the study institution, that number increased 4.5 times, a statistically significant difference (P = .020, chi2 test). Student survey data indicate that this increase reflects a general increase in the quality of radiology teaching in the study institution and specific changes in a required 2nd-year medical school course. CONCLUSION These results strongly suggest that good medical student teaching pays important dividends, not only to the departments that provide it but also to the profession of radiology as a whole. Exposing students to good radiology teaching early in their medical school careers is especially important. Radiology departments that provide outstanding medical student education should be studied to help develop a model of educational best practices.

Informing patients about risks and benefits of radiology examinations: A review article

Communicating the risks, benefits, and alternatives to a planned medical intervention is integral to high-quality patient care. When effective, such communication promotes patient autonomy, alleviates unfounded patient apprehension, and mitigates medicolegal liability. The topic of medical radiation adds to the usual challenges of effective medical communication some special challenges of its own. Among these is a lack of understanding by the general population and health professionals of the benefits and risks of medical radiation, which is compounded by unfamiliar terminology and units of measure. This is further complicated by the fact that many patients have poor comprehension of risk data in general. In this article, the authors present a case, review the ethical basis and legal history of informed consent, and explore the current initiatives, available resources, and further opportunities related to this challenging topic.

Pediatric digital chest imaging.

The Philips Computed Radiography system performs well with pediatric portable chest radiographs, handling the throughout of a busy intensive care service 24 hours a day. Images are excellent and routinely provide a conventional (unenhanced) image and an edge-enhanced image. Radiation dose is decreased by the lowered frequency of repeat examinations and the ability of the plates to respond to a much lower dose and still provide an adequate image. The high quality and uniform density of serial PCR portable radiographs greatly enhances diagnostic content of the films. Decreased resolution has not been a problem clinically. Image manipulation and electronic transfer to remote viewing stations appear to be helpful and are currently being evaluated further. The PCR system provides a marked improvement in pediatric portable chest radiology.

CT evaluation of normal interatrial fat thickness

PURPOSE This study was performed to determine the normal thickness of fat in the interatrial septum as demonstrated by CT. METHOD Eighty-seven subjects underwent helical chest CT examination as part of a separate protocol to compare the quantification of coronary artery calcification by CT to coronary angiographic findings, using a slice width of 3 mm, reconstructed every 1.5 mm. The thickness of the interatrial fat in both groups was measured anterior and posterior to the fossa ovalis. The mean and standard deviation were calculated. RESULTS The mean thickness of interatrial fat anterior and posterior to the fossa ovalis was 4.6 (SD = 2.5) and 3.7 (SD = 3.1) mm, respectively. CONCLUSION The normal range of thickness of the interatrial fat is 0-9.6 mm anterior to and 0-9.9 mm posterior to the fossa (2 SD above the mean).

Routine isotropic computed tomography scanning of chest: Value of coronal and sagittal reformations

Objective: We sought to evaluate the usefulness of coronal and sagittal reformations from isotropic chest computed tomography (CT) examinations. Methods: A total of 30 chest CT examinations were reconstructed into 2 sets of axial source images: 0.9-mm slice width with 0.45-mm reconstruction interval (isotropic) and 4-mm slices with 3-mm reconstruction interval. The isotropic dataset was reformatted into coronal and sagittal stacks with 4-mm slices. Three readers reviewed the image sets with 4-mm slice widths. Coronal and sagittal reformations were compared at the same sitting to axial images for depiction of anatomy and disease in the aorta, pulmonary arteries, hilar regions, mediastinum, lung parenchyma, pleura, diaphragm, thoracic spine, ribs, and trachea. A 5-point scale was used to determine whether nonaxial reformations showed anatomy and disease significantly better, somewhat better, same, somewhat worse or significantly worse than equivalent thickness axial source images. A 3-point scale was used to score if nonaxial image sets showed no, some, or significant additional information compared with the axial plane regarding the main diagnosis. Results: There was better visualization of the hilar regions, diaphragm, spine, and trachea on the coronal reformations compared with source axial images (P < 0.05). Sagittal reformations scored better than axial source images for aorta, pleura, diaphragm, spine, and ribs (P < 0.05). The coronal and sagittal series showed significant additional information in 11% and 9% of patients, respectively. Conclusion: Radiologists should consider the use of one or both of coronal and sagittal planes in addition to the axial series in routine interpretation of chest CT.