Peter G. Herman

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.

Low-dose spiral computed tomography of the thorax: comparison with the standard-dose technique.

RATIONALE AND OBJECTIVES This study was conducted to determine whether significant reduction in radiation dose (250 mAs-->50 mAs), in chest computed tomography (CT) using volume acquisition affects image quality or the detectability of pathologic findings in the lung and mediastinum. METHODS Phantom studies were conducted to evaluate resolution and noise level, then a patient study was then done. Fifty consecutive patients (10 normal and 40 abnormal) cases were examined. After a scan (250 mAs, 120OkVp) of the entire thorax, five additional slices (50 mAs, 120kVp) at the level of the abnormality were obtained. Three independent observers evaluated the visibility of normal lung and mediastinal structures, as well as image noise. The mean score was compared between the standard and low doses. In a second study, an independent evaluation of the presence or absence of pathologic findings was made by four observers. RESULTS Lucite phantom studies demonstrated diminished low-contrast resolution and increased noise level for the low-dose technique. Observers assessed more noise in the low-dose images (P < 0.001). The normal structures were judged to be more visible with standard dose (P < 0.01), but the magnitude of the judged differences was small especially in the lung. No differences were found in the detection of lung and mediastinal abnormalities (P > 0.10). CONCLUSIONS The low-dose technique was effective in demonstrating pathologic findings for the lung and mediastinum. Low-dose spiral CT should be considered as a viable alternative to standard-dose spiral CT.

Computerized volume measurement of brain structure.

Morphometric analysis of brain structures recently has become a main focus of interest in studies of some neuropsychiatric diseases. Limitations in imaging and mensuration methodology that is available currently for quantitative measurement of anatomic structures have prompted the development of a computerized system to study brain morphometry. A menudriven semi-automated computer system has been developed to assess in vivo brain morphometry using three-dimensional (3-D) magnetic resonance (MR), gradient echo, contiguous images of the whole brain. Accuracy of the system was tested with phantoms creating white on black contrast to simulate the brain tissue surrounded by subarachnoid cerebrospinal fluid (CSF), and a second set of phantoms creating black on white contrast to simulate the ventricular system in the brain tissue. The first set of phantoms was composed of three water-filled balloons (spherical, elliptical, and multiform) and a fresh postmortem brain. The second set of phantoms consisted of three rods of different diameters from a simple geometric plexiglass rod phantom and a life size cast of a human ventricular phantom. System accuracy was generally within 2.0% of the true volumes. System reliability was evaluated in three patient populations; 12 patients with Alzheimers disease, nine with schizophrenia and nine healthy controls age-matched to the patients with Alzheimers disease. Two independent observers measured the ventricular systems of these patients. Reliability of the system was addressed by the correlation between the two sets of measurements. For the sample as a whole, and each of the subgroups, the correlation between the two observers was 0.99. This system compares favorably with other morphometric methods reported.

Non-Hodgkin Lymphoma of the Lungs

Twenty-seven consecutive cases of pulmonary involvement by non-Hodgkin in lymphoma, including 2 cases of primary pulmonary disease, were anlyzed. The radiological manifestations of illness were divided into (a) nodular (subpleural, deep parenchymal, or perihilar), (b) pneumonic-alveolar (segmental or lobar), (c) bronchovascular-lymphangitic (central bronchovascular or diffuse lymphangitic), and (d) miliary-hematogenous. Histiocytic lymphoma was associated with infiltration of rapid onset in 6, cavitating nodules in 2, and diffuse lymphangitic dissemination in 9. Of 16 patients with lymphocytic lymphoma, 7 had lobar or segmental alveolar involvement.

Optimization of computed tomography technique to demonstrate the fine structure of the lung.

The purpose of this investigation was to optimize the reconstruction algorithm and the slice thickness of computed tomography (CT) for the study of the fine structure of the lung. In 75 patients, we performed routine thoracic CT examination and obtained two high-resolution CT (HRCT) slices at the same level using the standard and bone algorithms, or using the slice thickness of 1.5 mm and 3.0 mm. Side-by-side comparison of the standard and bone images revealed that more branching of the small vessels and more small bronchi could be recognized on the bone image than on the standard image. Thickened bronchovascular bundles and interlobular septa were demonstrated more clearly on the bone image than on the standard image. There was no significant difference in the CT attenuation value between the standard and bone images. The difference between 1.5 mm and 3.0 mm images when demonstrating the small vessels and bronchi was minimal in such lesions as lymphangitis carcinomatosa and radiation fibrosis. Thus HRCT, with a slice thickness of 1.5 mm and 3.0 mm reconstructed by the bone algorithm, is suitable for the demonstration of the fine structure of the lung.

Preoperative localization of parathyroid adenomas

During a 12-month period, 64 patients were operated on for primary hyperparathyroidism. Sixty-one had single adenomas and 3 had double adenomas. Preoperative imaging was used to localize the adenomas. Half of the patients (32 of 64) had magnetic resonance, thallium-201/technetium-99m subtraction scintigraphy, and high-resolution ultrasonography; the other 32 patients had 1 or 2 of the imaging modalities. Sensitivity and specificity of magnetic resonance imaging was 82 percent and 97 percent, respectively; the sensitivity and specificity of the other two modalities was 59 and 98 percent for subtraction scintigraphy and 73 and 98 percent for ultrasonography. The use of preoperative imaging facilitated surgical exploration, reduced operating time, and resulted in an increased number of successful operations. There were no negative explorations in this series as compared with 19 negative explorations (2.6 percent) in our prior experience with 720 operations.

Pulmonary scintigraphy in elastase-induced emphysema in pigs. Correlation with high-resolution computed tomography and histology

OBJECTIVES The objective of this study is to evaluate the mild physiologic changes of elastase-induced pulmonary emphysema in the pig by radionuclide scintigraphy and to correlate these findings with high-resolution computed tomography (HRCT) and histologic examination. METHODS Eight 7- to 12-week-old Yorkshire pigs were studied. Perfusion and ventilation studies were performed in six pigs at 1- or 2-week intervals after elastase instillation. HRCT was simultaneously performed for correlation with radionuclide scintigraphy. For the perfusion scans, technetium 99m (99mTc) macroaggregated albumin (MAA) was used, and both planar and single-photon emission CT (SPECT) images were obtained. Ventilation studies were performed with xenon-133 gas with dynamic sequential imaging. RESULTS Histopathologic findings demonstrated dilatation and destruction of the alveoli and were similar to those previously reported by the authors. The SPECT perfusion images showed significantly impaired perfusion of the involved segment of the lung, corresponding to the region where elastase was instilled. The planar xenon-133 ventilation scintigraphy did not show abnormal air trapping. The mild emphysema induced with elastase manifested as decreased and impaired perfusion with no detectable ventilation abnormalities. The sensitivity of SPECT perfusion studies for the detection of the mild changes of elastase-induced pulmonary emphysema were higher than that of HRCT. CONCLUSIONS The perfusion studies reflect functional or physiologic changes in contrast to structural changes seen on HRCT. This pig model was valuable to study the scintigraphic manifestation of elastase-induced pulmonary emphysema.

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.

Unusual noninfectious granulomas of the lung.

Illustrative cases of pulmonary granulomas with angitis and plasma cell granuloma of the lungs are presented. Experimental evidence suggests that the common pathogenesis of these processes is a cell-mediated immune response. Radiographic findings of these entities--nodules or infiltrates, some with cavities--are non-specific. Effective treatment is available for some of these processes. Lung biopsy as early as possible is recommended.

Pulmonary actinomycosis. A report of three cases.

The diagnosis of thoracic actinomycosis is readily made when the patient presents with the constellation of poor oral hygiene, pulmonary infiltrates, empyema, sinus tracts, and osteomyelitis of the ribs. However, in the absence of rib and chest wall involvement, the disease may be overlooked. Three cases of primary pulmonary actinomycosis are presented showing three different pulmonary forms of the disease and comprising (a) subacute patchy pulmonary infiltrates, (b) a cavitary lesion simulating tuberculosis, and (c) a central mass lesion simulating bronchogenic carcinoma.