Blood microcirculation in the lymph node during the primary immune response.

Microangiography performed after total blood replacement with contrast material provided complete visualization of the vascular structures of the lymph node. Starting of the 2nd day, there is capillary redistribution throughout the cortex of the lymph node. The previously rather avascular nodules dissolve, and the cortical lymphoid tissue becomes uniformly vascular. Beginning on the 2nd day and reaching its peak on the 5th day, there is a significant increase in diameter and density of the subcapsular and medullary cord capillaries. 15 days after the antigenic stimulus, the appearance of the microvasculature returns to normal. The postcapillary venules (the microvascular structures which follow the capillaries) are widely distributed throughout. Histologically, only a fraction of these venules have a high endothelial lining (HE venules). Therefore, it is suggested that among the postcapillary venules, those with high endothelial lining should be specifically denoted. Great individual variation in the number of HE venules was observed, and no correlation with the timing of the immune response could be established. Whether the microvascular changes described lead to cellular change or are mere expressions of it cannot definitely be stated. However, the significant hypervascularity along the intranodal lymph pathways and the diffuse, even redistribution of the capillaries and postcapillary structures could greatly facilitate the humoral and cellular exchange between the circulating blood, the circulating lymph, and the tissues of the lymph node.

Sex-related differences in tumor progression associated with altered lymphocyte circulation.

Male and female ACI rats were inoculated with the syngeneic H-4-II-E hepatoma, and the natural history of the tumor, histopathology, and lymphocyte migration were studied. The tumor formed a.s.c. mass in all 16 males and in 22 of the 26 females given injections. In the males, tumors progressed, and all animals died with the mean survival time of 54 days. Complete tumor regression was observed in all but two females. In the females, there was prominent lymphocytic infiltration of the tumor, while males had no cellular reaction at the tumor site. The regional lymph nodes in males usually contained metastases and were nonreactive. The female lymph nodes did not contain metastases but contained many lymphocytes within the peripheral sinus and sinusoids. Six male-female pairs were castrated before tumor inoculation. Castration had no effect on the natural history or the etiology of the tumor. Comparing seven normal control male-female littermate pairs, there were no differences in lymphocyte accumulation in the lymph nodes 22 hr following injection of 51Cr-labeled syngeneic lymphocytes. In seven tumor-bearing male-female littermate pairs, there was a significant decrease in lymphocyte migration to the lymph nodes (p less than 0.001) in tumor-bearing males as compared to that in both their female littermates and control males. Depressed lymphocyte circulation in the males was associated with rapid progression of tumors resulting in the death of the animals. Unimpaired lymphocyte mobilization in the tumor-bearing females was associated with complete regression in most animals.

Pathologic patterns of Serratia marcescens pneumonia.

To characterize the pulmonary lesions caused by Serratia marcescens, the authors reviewed all autopsy-culture-proven cases of S. marcescens pneumonia occurring at their hospital between 1968 and mid-1980. In 16, S. marcescens was the only organism cultured from the lungs during life or at autopsy. This report describes primarily these pure infections. Two histopathologic reactions were seen. Nine non-neutropenic patients had acute, hemorrhagic bronchopneumonia, seven with microabscesses and two with larger cavities. In seven, distinctive vasculitis was apparent in vessels larger than 75 microns in diameter; intramural gram-negative rods were identified in two. Seven immunosuppressed patients had diffuse neutropenic pneumonitis resembling diffuse alveolar damage, with extensive intra-alveolar fibrinous exudates and pulmonary hemorrhage. In two patients, bacteria without cellular reaction were present. In patients with prolonged infections, focal areas of intra-alveolar organization and bronchiolitis obliterans accompanied both patterns. Since the incidence of nosocomial S. marcescens infection is increasing and since pneumonia caused by this organism is recognizable histologically, autopsy cultures positive for S. marcescens should not be disregarded.

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.

High-resolution computed tomography of the pig lung.

Computed tomographic (CT)-anatomic correlation of the lung was performed on young Yorkshire pigs. After in vivo CT, the lungs were removed, fixed, and dried. The lung specimens were studied with CT and on several specimens, bronchography and arteriography also were done to establish the normal anatomy. Subsequently, the specimens were sliced at corresponding levels of the CT cuts and histology was done as needed. The lobules in the pig lung are very well demarcated. On the specimen radiographs with bronchography and in vivo CT in pulmonary edema, "sublobular units" can be readily identified that are rather uniform in size. On the in vivo CT with the standard algorithm, the relationship between the branches of the pulmonary artery and bronchus can be shown to the level of segmental bronchi. With the bone detail algorithm, vessels are clearly shown and lobar bronchi become visible. On in vivo CT, the lobular demarcations cannot be seen in the normal pig but clearly are visible in pulmonary edema. In cases of pulmonary edema, in addition to the lobules, the sublobular units and the sublobular bronchi, which measure .5 to .7 mm in diameter, also can be appreciated. Because of the well-developed pulmonary lobules and the uniformly sized sublobular units, the Yorkshire pig is potentially a good model for radiologic-pathologic correlation, particularly of airspace disease.

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.

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.

The renal collecting system after medullary damage.

The micromorphology of the renal collecting system after unilateral papillectomy in rabbits was investigated. Two weeks to six months after papillectomy, tubular micropuncture studies were performed. Cleared specimens were studied by light microscopy and microradiography. Histologic and physiologic correlations were made. At two to four weeks, the papillectomized kidneys were smaller and had smooth, mottled surfaces. At one to six months, there was cortical scarring with decreased concentrating ability. Ductal micropuncture revealed dilated collecting tubules and ducts which were obstructed at the papillectomy site. It is concluded that obstructed collecting ducts may be responsible for the cortical atrophy and are the primary cause of renal cortical damage after papillectomy in our model.

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.

Experimental pulmonary infarction in a pig model.

RATIONALE AND OBJECTIVES: The authors sought to develop a reliable animal model for experimental pulmonary infarction, to evaluate it with radiologic-pathologic correlation, and to determine the use of high-resolution computed tomography (HRCT) in monitoring parenchymal lung damage due to infarction. METHODS: Selective left lower lobe pulmonary artery occlusion was performed in seven Yorkshire pigs with transcatheter silicone elastomer injection. After occlusion, 99m technetium (99mTc) macroaggregated albumin perfusion lung scans and sequential in vivo HRCT lung scans were obtained from days 0 to 46. The in vivo radiologic findings were correlated with specimen radiography, specimen HRCT, and histologic findings. RESULTS: A complete and permanent arterial occlusion was achieved, involving up to three orders of branching distal to the catheter. An anatomically defined perfusion defect was seen on 99mTc lung scans corresponding to the occluded area. HRCT changes consisted of confluent densities progressing to mixed alveolar and interstitial opacities within the first week after embolization. In the follow-up period, marked parenchymal clearing was observed. In all cases after pulmonary artery occlusion, the histologic findings were characteristic of pulmonary infarction and demonstrated alveolar edema, hemorrhage, limited alveolar wall damage, and septal thickening followed by residual fibrosis. CONCLUSION: Using this model, it is feasible to produce pulmonary infarction in the pig which may potentially be useful to study the pathophysiologic and radiologic changes of pulmonary infarction.

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.

Sequential morphologic changes of elastase-induced pulmonary emphysema in pig lungs. Evaluation by high-resolution computed tomography.

The authors evaluated the early morphologic changes of elastase-induced pulmonary emphysema in the pig and correlated the findings with high-resolution computed tomography (HRCT). Nine Yorkshire pigs were included in this investigation; in seven, pulmonary emphysema was induced by 2 mg/kg body weight of elastase instilled selectively into the left lower lobe bronchus. Animals were studied by CT at 0, 1, 2, 3, 7, 14, and 21 days. At the completion of the experiment, the lungs were removed, inflated, fixed and dried, and subsequently sliced corresponding to the CT sections. The gross appearance, histologic appearance, and HRCT were correlated. On HRCT, sequential changes from early edema to development of emphysema were noted. Panlobular, centrilobular and paraseptal emphysema were observed. Elastase-induced pulmonary emphysema in the pig is a useful and reproducible animal model, and high-resolution computed tomography depicts the morphologic changes observed both by gross pathologic observations and histologic observations.

Intralobular distribution of oleic acid-induced pulmonary edema in the pig. Evaluation by high-resolution CT.

The objective of this study was to elucidate the features of experimentally induced pulmonary edema at the lobular level, using high-resolution CT (HRCT) with pathological correlation. We selected the pig as the experimental animal because the pig has well-defined pulmonary lobules. Twelve Yorkshire pigs were included in this study. Five animals were used for studying normal anatomy of the pig lung. Pulmonary edema was induced by oleic acid infusion in 7 pigs. All computed tomographic (CT) scans were performed on a GE 9800 scanner, using 1.5 mm slice-thickness, 16 cm field of view with 512 X 512 matrix and bone reconstruction algorithm. The animals were killed after CT scans and the lungs were removed, inflated, fixed and dried, and subsequently sliced in sections which corresponded to the CT sections. Using CT images, specimen radiography, and histology, we studied the intralobular distribution of pulmonary edema in selected lobules of each animal. Oleic acid infusion caused multifocal hemorrhagic pulmonary edema within the pulmonary lobule. The distribution was uneven and areas surrounding the lobular bronchi were less involved. HRCT permits evaluation of morphological changes of oleic acid-induced pulmonary edema at the lobular level. The intralobular distribution of the lesions may provide additional information about the mechanism of permeability pulmonary edema.

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.

Imaging of lymphoid structures with indium-111-labeled lymphocytes.

The ability of indium-111 (111In)-oxine-labeled syngeneic lymphocytes to migrate normally and their suitability for imaging both normal lymphoid structures and those with metastatic disease were assessed. Sixty-two ACI rats were studied, 34 of which received injections in the left foot pad with 1 X 10(6) syngeneic H-4-II-E hepatoma cells nine to 44 days before imaging. Most animals were bearing palpable tumors when imaged. In 53 experiments, 1-6 X 10(8) 111In-oxine-labeled lymphocytes with a labeling concentration of 5-80 microCi/10(8) cells were injected intravenously. Gamma camera images were obtained 22 hours later. After the last image, the animals were killed. The lymph nodes, liver, spleen, lungs, and left femur were dissected, and the recovered radioactivity was determined in a gamma well counter. Lymph nodes could be partially or completely visualized in 70% of the animals (15 tumor-bearing and 16 normal out of 44 technically satisfactory experiments). Large metastatic nodes were seen clearly. Lymphocytes labeled with 111In-oxine exhibited a normal migration from blood to lymph nodes.

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 Alzheimer's disease, nine with schizophrenia and nine healthy controls age-matched to the patients with Alzheimer's 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.

Radiation-induced lung injury using a pig model. Evaluation by high-resolution computed tomography.

RATIONALE AND OBJECTIVES: To assess the early phase of radiation-induced lung injury using high-resolution computed tomography (CT) under experimental conditions and to perform precise CT-pathologic correlation. METHODS: Five Yorkshire pigs received a single dose of 12.5 Gy to the right lower lung. Computed tomographic images were obtained at 2-week intervals. The animals were killed after follow-up periods of 4-16 weeks. The lungs were removed, inflated, fixed, dried, and sliced corresponding to the CT sections. Computed tomography, specimen radiography, and histologic findings were correlated. RESULTS: Various CT findings were observed during the first 16 weeks, including ground-glass opacity, discrete consolidation, patchy consolidation, thickened interlobular septum, and bronchovascular bundle. Ground-glass opacity was associated with thickened alveolar wall and scattered tiny fibrotic foci. Thickened interlobular septum and bronchovascular bundle were the results of fibrosis adjacent to these structures. Discrete consolidation correlated with intraalveolar edema with hemorrhage and infiltration of inflammatory cells. CONCLUSIONS: High-resolution CT correlated well with pathology of the lung due to radiation injury as verified by precise radiologic-pathologic correlation.