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Biomedical subjects

C J Bergin

Publications and source records attributed to C J Bergin.

At least 37 records · Page 2Linked to original sources
PubMed1994

Spiral CT of the lungs: optimal technique and resolution compared with conventional CT.

OBJECTIVE: The purpose of this study was to compare the resolution of spiral and conventional CT for imaging the lungs and to optimize spiral CT techniques for imaging lung parenchyma. MATERIALS AND METHODS: A line-pair phantom, a dried lung specimen, and three human subjects were scanned. Spiral CT scans obtained on a Somatom PLUS-S CT scanner were compared with conventional CT scans. In addition, the influence of different collimation (1,3, 5, and 8 mm), pitch (1 and 2), display kernel (UltraHi, Hi, Standard, and Soft), and interpolation algorithms (360 degrees and 180 degrees linear interpolation) on spiral CT scans was evaluated. Scans obtained by using different techniques were compared for edge sharpness, contrast resolution, overall visibility of vessels, and noise. RESULTS: With the line bars parallel to the z-axis, a spatial resolution of 7.7 Ip/cm was obtained at all four levels of collimation used for both spiral and conventional CT scanning. Resolution in the z-axis (i.e., direction of table movement) on spiral CT scans decreased markedly when alignment of the line-pair phantom bars was changed to 45 degrees. Resolution along the z-axis decreased with increasing collimation, and this effect was more marked on spiral CT scans than on conventional CT scans. The relative decrease in resolution on spiral CT scans was visible on scans of human subjects only at narrow collimation (1 and 3 mm). Optimal visualization of structures in the lung parenchyma was obtained by using 3-mm collimation and the UltraHi display kernel. The choice of table speed (pitch 1 vs 2) and interpolation algorithm (360 degrees vs 180 degrees linear interpolation) did not significantly affect the image quality of scans of human subjects. CONCLUSION: CT scans of the lung obtained by using spiral and conventional modes at wide collimation (5 and 8 mm) show no differences in resolution, although, at narrow collimation (1 and 3 mm), curved structures such as walls of bullae and fissures are somewhat indistinct. On spiral CT scans of the lungs, narrow collimation and the UltraHi display kernel provide the best image resolution and have more effect on image quality than does choice of table speed or linear interpolation algorithm.

Humans↗
PubMed1994

Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings?

OBJECTIVE: High-resolution CT findings in patients with asbestosis include subpleural curvilinear densities, subpleural density in dependent portions of the lung, parenchymal bands, thickened septal lines, and honeycomb lung. Our objective was to examine the prevalence of these CT findings in a random group of patients scanned for a variety of clinical reasons not specifically related to occupational exposure. MATERIALS AND METHODS: One hundred sixty-eight CT studies of the thorax were performed at six levels in 168 patients examined for a variety of clinical indications. The scans were evaluated by two radiologists for the presence of subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, thickened septal lines, and honeycomb lung. RESULTS: CT scans of 11 patients showed pleural plaques suggesting previous exposure to asbestos. Among the 157 studies showing no evidence of pleural plaques, CT scans showed subpleural curvilinear densities in dependent areas in 32 (20%); subpleural curvilinear densities in nondependent areas in 19 (12%); parenchymal bands in 47 (30%); thickened septal lines in dependent areas in 93 (59%), and septal lines in nondependent areas in 67 (43%); subpleural density in dependent areas in 66 (42%); and honeycomb lung in five (3%). CONCLUSION: Subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, and thickened septal lines occur as isolated and as combined CT findings in patients with a variety of underlying diseases or conditions unrelated to asbestosis and by themselves are nonspecific findings. Their occurrence, even in patients with CT evidence of pleural plaques, does not necessarily indicate the presence of asbestosis.

Asbestosis↗
PubMed1993

MR imaging to detect chest wall and pleural involvement in patients with lymphoma: effect on radiation therapy planning.

OBJECTIVE: The purpose of this study was to determine the influence that accurate MR detection of chest wall and pleural disease has on the type and extent of radiation therapy subsequently performed in patients with thoracic lymphoma. MATERIALS AND METHODS: MR images and CT scans of the chests of 57 patients who had biopsy-proved lymphoma were retrospectively examined for evidence of involvement of the chest wall and pleura. For patients with thoracic lymphoma, we compared radiation portals and dosage designed by using information from MR images with portals and dosage designed by using information from chest radiographs and CT scans. RESULTS: Chest wall or pleural disease was detected in 22 of the 57 patients examined. Chest wall disease was identified on MR images in 20 patients (29 sites) and pleural disease in 14 patients (16 sites). Chest wall and pleural disease were identified on CT scans in seven and five patients, respectively. Of the 15 patients who received radiation therapy, three (20%) had treatment planning altered, either by increasing the area exposed to radiation or by increasing the radiation dose, because of findings noted only on MR images. CONCLUSION: Chest wall and pleural sites of disease that may be detected only on MR images can be important in designing appropriate radiation portals and dosage for patients who have chest lymphoma.

Adolescent↗
PubMed1993

Magnetic resonance imaging of lung parenchyma.

Imaging of the lungs presents a unique challenge for MR technology. Signal from lung parenchyma is limited by low proton density, the effects of motion and susceptibility, and a multiexponential T2 relaxation time. We have illustrated the use of spin echo and projection reconstruction MR sequences in imaging lung parenchyma, and the use of a GRE sequence in imaging the pulmonary vascular tree.

Humans↗
PubMed1992

MR imaging of lung parenchyma: a solution to susceptibility.

The authors have developed a pulse sequence for imaging lung parenchyma with projection reconstruction magnetic resonance (MR) imaging that reduces the effects of motion and susceptibility. In this study, the projection reconstruction technique was further modified by optimizing MR signal frequencies for reconstructing the images. This was done by means of one of two methods. With the first method, a susceptibility map was derived from the raw image data and this map was used to indicate the optimal frequencies for reconstructing the images. The second method of susceptibility correction was a postprocessing technique in which the optimal reconstruction frequencies were selected with use of specific focusing criteria to generate the least blurred image. The effect of using susceptibility map correction on a phantom was demonstrated, and both of these methods were used to improve the visibility of pulmonary structures on images of subjects with normal and abnormal lungs.

Humans↗
PubMed1992

Diagnosis of bronchiolitis obliterans in heart-lung transplantation patients: importance of bronchial dilatation on CT.

OBJECTIVE: The purpose of this study was to evaluate the significance of bronchial dilatation identified on high-resolution CT scans obtained after heart-lung transplantation. Bronchial dilatation has been identified on pathologic specimens and on high-resolution CT scans of patients with severe bronchiolitis obliterans after lung transplantation, but this finding has not previously been systematically studied as a manifestation of this complication. MATERIALS AND METHODS: We studied the high-resolution CT scans of 16 patients who had had heart and lung transplantation at least 1 year before, and compared the percentage of dilated bronchi with evidence of small airways disease shown on pulmonary function tests. RESULTS: We found a close correlation between the percentage of bronchi in the lower lobes that were dilated and the percent predicted forced expiratory volume in 1 sec, forced vital capacity, and forced expiratory flow between 25% and 75% of vital capacity. No other feature identified on high-resolution CT scans correlated with pulmonary function abnormalities. CONCLUSION: We conclude that dilatation of the lower lobe bronchi is a good indicator of bronchiolitis obliterans in this population, and that the percentage of dilated bronchi generally increases with increasing pulmonary dysfunction.

Biopsy↗
PubMed1991

Lung parenchyma: projection reconstruction MR imaging.

Magnetic resonance (MR) imaging of lung parenchyma is limited by the low proton density and short T2 in the lung as well as the effects of susceptibility and motion. The MR imaging appearance of lung parenchyma was investigated with a pulse sequence that offers some solutions to these problems. This sequence employs projection reconstruction (PR) acquisition gradients and a section-selective excitation pulse designed to eliminate the need to refocus and to allow low-frequency k-space data to be collected with minimal delay. Echo times as short as 50 microseconds can be achieved, producing a proton-density-weighted image. An excised inflated lung specimen and specimens from human subjects with normal lungs (n = 3), pulmonary arteriovenous malformations (n = 1), bronchogenic carcinoma (n = 1), and bullous lung disease with lung metastases (n = 1) were examined. Signal intensity from lung parenchyma and visibility of pulmonary structures were superior on images obtained with the PR MR imaging technique compared with spin-echo images.

Humans↗
PubMed1991

Lung parenchyma: magnetic susceptibility in MR imaging.

Magnetic susceptibility effects in magnetic resonance (MR) imaging of normal lung parenchyma occur because of magnetic-field inhomogeneities induced by the microscopic heterogeneity of the lung. The effects on MR imaging of the lung are loss of signal from intravoxel phase dispersion (measured with T2') and a shift in the macroscopic resonant frequency from that of water toward that of air (delta v). These effects of MR imaging at 1.5 T were quantitated by measuring T2' decay and delta v at different locations in the lungs of two adult volunteers and one excised inflated human lung. The average T2' was 7 msec in the excised inflated specimen and 6.3 msec in normal in vivo lungs. There was a gravitational increase in T2' from nondependent to dependent lung. T2' increased to 35 msec in atelectatic lung tissue and to more than 140 msec in tumor. The macroscopic resonant lung frequency increased to 3.6 ppm more than that of mediastinal muscle. These values are important for developing MR pulse sequences appropriate for imaging lung parenchyma.

Humans↗
PubMed1990

Acute lung rejection after heart-lung transplantation: correlation of findings on chest radiographs with lung biopsy results.

This retrospective study was performed to determine if the chest radiograph could serve as a predictor for acute lung rejection in heart-lung transplantation patients. The findings on chest radiographs were correlated with the results of transbronchial biopsies in 16 heart-lung transplantation patients. The chest radiographs immediately preceding 83 biopsies were evaluated for a variety of findings. The histopathologic results of the lung biopsies were divided into five categories: (1) acute lung rejection (n = 25); (2) suggestive, but not diagnostic, of acute lung rejection (n = 8); (3) nonspecific (n = 26); (4) infection (n = 17); and (5) normal lung (n = 9). Biopsies from two patients showed both acute lung rejection and cytomegalovirus infection and were included in both categories. These histopathologic results were then correlated with the radiologic observations. We found that the combination of septal lines and new or increasing pleural effusions, without concomitant increase in cardiac size or vascular pedicle width, or evidence of vascular redistribution, indicated acute lung rejection with a sensitivity of 68% (17/25), specificity of 90% (52/58), and overall accuracy of 83% (69/83). We conclude that the chest radiograph is a useful indicator of acute lung rejection.

Adult↗
PubMed1989

Sarcoidosis: correlation of pulmonary parenchymal pattern at CT with results of pulmonary function tests.

The appearances of the lungs on radiographs and computed tomographic (CT) scans were correlated with degree of uptake on gallium scans and results of pulmonary function tests (PFTs) in 27 patients with sarcoidosis. CT scans were evaluated both qualitatively and quantitatively. Patients were divided into five categories on the basis of the pattern of abnormality at CT: 1 = normal (n = 4); 2 = segmental air-space disease (n = 4); 3 = spherical (alveolar) masslike opacities (n = 4); 4 = multiple, discrete, small nodules (n = 6); and 5 = distortion of parenchymal structures (fibrotic end-stage sarcoidosis) (n = 9). The percentage of the volume judged to be abnormal (CT grade) was correlated with PFT results for each CT and radiographic category. CT grades were also correlated with gallium scanning results and percentage of lymphocytes recovered from bronchoalveolar lavage (BAL). Patients in CT categories 1 and 2 had normal lung function, those in category 3 had mild functional impairment, and those in categories 4 and 5 showed moderate to severe dysfunction. The overall CT grade correlated well with PFT results expressed as a percentage of the predicted value. In five patients, CT scans showed extensive parenchymal disease not seen on radiographs. CT grades did not correlate with the results of gallium scanning or BAL lymphocytes. The authors conclude that patterns of parenchymal sarcoidosis seen at CT correlate with the PFT results and can be used to indicate respiratory impairment.

Airway Obstruction↗
PubMed1989

Stump neuroma masquerading as recurrent malignancy on chest roentgenogram.

An amputation neuroma is a nerve's attempt at repair following amputation. While many are asymptomatic, some present as a painful mass. We describe a patient who, following a forequarter amputation for sarcoma, developed a stump neuroma that was unusual because it was first discovered on a routine chest roentgenogram.

Amputation Stumps↗
PubMed1989

Chronic lung diseases: specific diagnosis by using CT.

We evaluated patterns of abnormal lung parenchyma on CT scans in six specific chronic lung diseases and then applied those findings in the differential diagnosis of these lung parenchymal patterns in 56 subjects. There were 48 patients with chronic lung diseases (43 with histologic proof) consisting of usual interstitial pneumonia (n = 20), sarcoidosis (n = 16), lymphangitic carcinomatosis (n = 7), lymphangioleiomyomatosis (n = 2), drug toxicity (n = 2), and eosinophilic granuloma (n = 1). Including eight CT scans of normal control subjects, 56 CT scans were assessed independently by two readers (R1 and R2). Chest radiographs, most of which were obtained within 1 week of CT examination, were available in 48 of the 56 subjects. CT scans were evaluated for specific parenchymal features including disease distribution, lung distortion, thickening of bronchovascular bundles and polygon walls, bronchiectasis, cysts, and nodules, to determine the association of each abnormal feature with the different diseases. Diagnosis was then made from the overall CT appearance of the lungs and, on a separate occasion, from the appearance of the chest radiograph. The correct diagnosis was made from the CT appearance in 54 of 56 patients (R1) and in 50 of 56 patients (R2). Correct diagnoses were made from the chest radiographs in 42 of 48 patients (R1) and 43 of 48 patients (R2). We have identified features that are reproducible and useful when describing CT scans of patients with chronic lung diseases. Interpretation of the appearance of the lung on CT scans was accurate in diagnosing usual interstitial pneumonia, sarcoidosis, and lymphangitic carcinomatosis.

Chronic Disease↗
PubMed1987

CT of interstitial lung disease: a diagnostic approach.

Weibel divided the pulmonary interstitium into three compartments: axial, parenchymal, and peripheral. Heitzman and others have shown that certain interstitial diseases selectively involve these compartments. A model is proposed of the CT appearances in interstitial lung disease based on Weibel's divisions. To assess the validity of this model, the distribution of disease was studied in 44 patients with proven interstitial lung disease. Lymphangitic carcinomatosis (n = 5), lymphoma (n = 2), and sarcoid in two of three patients typically involved the axial compartment. The middle (or parenchymal) compartment was abnormal in advanced stages of many interstitial diseases, particularly granulomatous diseases and drug toxicity (n = 2) in this series, but diffuse changes were seen early in extrinsic allergic alveolitis (n = 4). The peripheral compartment was predominantly affected in idiopathic pulmonary fibrosis (n = 9), rheumatoid lung (n = 3), and scleroderma (n = 1). Prominent nodularity was a feature of lymphangitic carcinomatosis and of the granulomatous diseases, silicosis and sarcoid. The presence or absence of nodules coupled with CT demonstration of differential involvement of the three interstitial compartments is useful in limiting diagnostic possibilities in interstitial disease. By more accurately showing disease distribution, a more reasonable approach to lung biopsy options may be developed.

Humans↗
PubMed1986

CT in the qualitative assessment of emphysema.

To assess the ability of CT to demonstrate the different types of emphysema, the CT appearance was compared with the corresponding barium-impregnated pathologic specimens cut in the transverse plane, in four patients with emphysema. The CT appearance was also compared with the chest radiographs of two patients with irregular emphysema associated with progressive massive fibrosis. The parenchymal destruction visualized on CT in the patients with mild and moderate centriacinar emphysema was distinctly different from that seen in the patient with panacinar emphysema in appearance and distribution. Paraseptal and irregular emphysema were also well demonstrated using CT. Window widths between 800 and 1,500 were found to demonstrate the parenchymal changes most accurately. We conclude that CT can help to identify the presence of emphysema and to distinguish radiologic characteristics of the different types of emphysema.

Humans↗