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Biomedical subjects

P G Herman

Publications and source records attributed to P G Herman.

At least 19 recordsLinked to original sources
PubMed1994

Bleomycin-induced fibrosis in pigs: evaluation with CT.

PURPOSE: To establish an animal model for use in evaluation of early morphologic changes of pulmonary fibrosis by means of precise correlation of findings at thin-section computed tomography (CT) and pathologic findings. MATERIALS AND METHODS: Bleomycin (1.0-2.5 U per kilogram of body weight) was delivered selectively into the left lower lobe bronchus via balloon catheter in five Yorkshire pigs. Sequential CT examinations were performed at regular intervals. The animals were killed at follow-up of 5 days to 4 weeks. At autopsy, the lungs were removed, inflated, fixed and dried, and subsequently sliced into sections that corresponded to the CT sections. The fixed lungs were examined with thin-section CT, radiography, and histologic studies. RESULTS: There was good correlation between pathologic findings at CT and specimen radiography. Histologic study revealed signs of pneumonitis and developing fibrosis. CONCLUSIONS: This disease model is suitable for radiologic and pathologic evaluation of interstitial fibrosis. CT was sensitive in detection of bleomycin-induced abnormalities.

Animals↗
PubMed1992

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.

Animals↗
PubMed1992

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.

Animals↗
PubMed1991

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.

Animals↗
PubMed1991

Solitary pulmonary nodules: comparison of classification with standard, thin-section, and reference phantom CT.

Standard, thin-section, and reference phantom computed tomography (CT) were performed to evaluate 75 consecutive patients with solitary pulmonary nodules. Follow-up was available for 62 nodules in 59 patients; 53 of the nodules were benign and nine were malignant. Twenty-one of the 62 nodules were assessed as benign with thin-section CT, while 33 of the 62 nodules were assessed as benign with reference phantom CT. Two of the nodules classified as benign with both thin-section and reference phantom CT proved to be malignant (a peripheral, ossified carcinoid and a 3.5-cm-diameter calcified carcinoma). The sensitivity of reference phantom CT (58%) for classification of benign nodules was higher than the sensitivity of thin-section CT (36%). The sensitivity of standard CT was lowest (12%). The presence of fat at thin-section CT was a reliable criterion for benignancy in six hamartomas. While both thin-section and reference phantom CT were useful in the identification of benign pulmonary nodules, reference phantom CT increased sensitivity by 22% compared with thin-section CT.

Adult↗
PubMed1991

Limitations in distinguishing malignant from benign lesions of the breast by systematic review of mammograms.

Our objective was to assess whether or not a systematic review of mammographic descriptors would result in improved classifications of nonpalpable lesions of the breast and reductions of biopsies for benign conditions. The prelocalization mammograms of 200 consecutive patients who had 231 biopsies were reviewed in random order by four radiologists experienced in mammography. Each reader assessed the presence of 32 specific descriptors regarding masses and calcifications. The following descriptors were highly associated with malignancy: for masses, inhomogeneous density; irregular shape; spiculated borders; and for calcifications, many calcifications; microcalcifications; linear or branching patterns, or both, and high spatial density. For masses, the descriptors highly associated with benignity were homogeneous density, oval shape and sharp or lobulated borders. For calcifications, the descriptors highly associated with benignity were solid, round and irregularly shaped. Readers indicated their over-all rating of each lesion, ranging from definitely benign to definitely malignant. Ratings were compared with the findings of pathologic reports (181 benign to 50 malignant), and receiver operating characteristic analyses were performed. The areas under the curves (A[z]) varied from 0.65 to 0.78. If biopsies had not been performed on those patients who were judged to have most likely benign lesions, one could reduce the number of biopsies for benign conditions by 48 to 69 per cent; however, 18 to 46 per cent of the malignancies would be missed. We conclude that diagnoses based on a systematic review of descriptors are not sufficiently accurate to reduce the number of mammary biopsies.

Adult↗
PubMed1990

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.

Cerebral Ventricles↗
PubMed1990

Limited correlation of left ventricular end-diastolic pressure with radiographic assessment of pulmonary hemodynamics.

Left ventricular end-diastolic pressure (LVEDP) is a reliable indicator of the diastolic function of the left ventricle. The purpose of this study was to correlate the radiographic assessment of pulmonary hemodynamics with LVEDP. The study population consisted of 104 consecutive patients with four categories of LVEDP: less than 13 mm Hg (n = 26), 13-19 mm Hg (n = 30), 20-24 mm Hg (n = 24), and more than 24 mm Hg (n = 24). Chest radiographs obtained within 24 hours of cardiac catheterization were assessed for evidence of congestive heart failure (CHF) by three experienced radiologists. Findings were graded from 0 to 3 (normal to abnormal) on the basis of the following signs of CHF: redistribution, perihilar and perivascular haze, peribronchial cuffing, pulmonary artery-bronchus ratio, septal lines, subpleural edema, air-space edema, pleural effusion, cardiomegaly, and overall radiographic assessment of CHF. A consensus report was then generated. In patients with LVEDP over 20 mm Hg, 38% did not show CHF in the overall assessment. Correlation between radiographic signs of CHF and LVEDP was limited.

Cardiac Catheterization↗
PubMed1989

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.

Animals↗
PubMed1989

Pulmonary parenchymal disease: evaluation with high-resolution CT.

Usefulness of high-resolution computed tomography (HRCT) in locating pulmonary parenchymal disease in relation to the pulmonary lobule was evaluated in 71 patients, including 30 with normal pulmonary parenchyma and 41 with various pulmonary diseases. Both 10-mm-thick sections and 1.5- or 3.0-mm-thick HRCT scans were obtained. Distribution of pulmonary parenchymal disease was classified as centrilobular, panlobular, perilobular, bronchovascular, or nonlobular. Intralobular classification of disease distribution was more feasible in less severely diseased regions. HRCT revealed thickened intralobular bronchovascular bundles in patients with bronchiolitis obliterans, mycoplasma pneumonia, and pulmonary tuberculosis and thickening of both bronchovascular bundles and perilobular structures in patients with sarcoidosis, lymphangitis carcinomatosa, and malignant lymphoma. Centrilobular areas of increased attenuation were seen in patients with bronchopneumonia and pulmonary cryptococcosis. Centrilobular emphysema and bronchiolectasis were recognized only on HRCT images. The improved clarity and sharpness of parenchymal abnormalities on HRCT images, even in severely involved areas, provide additional information about disease distribution.

Female↗
PubMed1989

Comparison of CT and chest radiographs in the evaluation of post-therapy lymphoma patients.

A comparative study of the efficacy of thoracic CT (TCT) and chest radiograph for the assessment of complete remission, residual or recurrent disease, was undertaken on 31 post-therapy lymphoma patients (23 Hodgkin's, 8 non-Hodgkin's). The TCT and chest radiograph were evaluated independently. Compared with the chest CT, the sensitivity of the chest radiograph was low (56%). The confidence level of abnormal findings on the chest radiograph was lower, Additional diagnostic information provided by TCT influenced the clinical management in 33% of the cases. Compared with the chest radiograph, TCT had a higher diagnostic and management efficacy at the follow-up evaluation of post-therapy lymphoma patients.

Combined Modality Therapy↗
PubMed1988

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.

Adenoma↗
PubMed1988

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.

Humans↗
PubMed1986

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.

Animals↗
PubMed1985

Distribution and mechanism of uptake of 111InCl3 in a tumor model for lymph node metastases.

The localization of 111In activity in the tumor and draining lymph nodes of the H-4-II-E ACI rat hepatoma was investigated following the injection of 111In-chloride. In this tumor model, the tumors metastasize to the regional lymph nodes in male rats only. The following experiments were performed: (a) biodistribution of 111In; (b) correlation of 111In uptake with [3H]thymidine; (c) gamma camera imaging; (d) autoradiography; (e) iron competition and (f) binding of 131I-transferrin to H-4-II-E cells. Tumor-to-muscle ratios of 111In in males were 4.9:1 in the primary tumor and 9.1:1 in the metastatic lymph nodes 24 h post injection. In the lymph node metastases in the males, a significant correlation between 111In uptake and [3H]thymidine was observed (r = 0.737) suggesting that 111In uptake in the metastases is related to cellular proliferation. No such correlation was observed in either primary tumors (both male and female) or in the draining lymph nodes of the females. Metastatic lymph nodes in males could be detected in gamma camera images while draining nodes in females could not be delineated. Injection of ferric citrate prior to 111In administration resulted in a significant reduction of 111In uptake in the liver, spleen and tumor and increased the amount of activity recovered from the kidney. Measurements of the binding of 131I-labeled rat transferrin to H-4-II-E cells in vitro suggest that these cells display transferrin receptors.

Animals↗
PubMed1984

Differential diagnosis of mediastinal fluid levels visualized on computed tomography.

Mediastinal lesions containing three types of fluid levels were studied by computed tomography. Air-fluid, fat-fluid, and fluid-fluid levels were easily recognized and were caused by a colonic interposition, a cystic teratoma, and a hematoma, respectively. Computed tomography can be useful for detection and precise diagnosis of mediastinal lesions that contain fluid levels.

Adult↗
PubMed1983

Bedside chest radiography: diagnostic efficacy.

In order to evaluate the efficacy of bedside chest radiography, a prospective study was completed of 140 patients admitted to the surgical and medical intensive care units over a two-month period. A total of 1132 consecutive bedside radiographs was analyzed for malposition of tubes and lines and interval changes in the cardiopulmonary findings. The median number of bedside radiographs per patient was 0.7 per day. Endotracheal or tracheostomy tubes were present in 54% of all examinations; among these 12% were malpositioned. Central venous catheters were present in 47%; among these 9% were malpositioned. Interval changes regarding cardiopulmonary findings (pneumothorax, collapse, diffuse or focal infiltrate, effusion, and congestive heart failure) were present in 44% of the radiographs after the admission one. Overall there were new findings or changes affecting the patient's management present in 65% of the radiographs. The use of bedside radiography appeared to be appropriate.

Adult↗