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Biomedical subjects

C J Bergin

Publications and source records attributed to C J Bergin.

At least 19 recordsLinked to original sources
PubMed2000

Predictors of patient response to pulmonary thromboendarterectomy.

OBJECTIVE: We sought to identify imaging features that help predict surgical success in patients undergoing thromboendarterectomy. MATERIALS AND METHODS: Thirty-nine consecutive patients who underwent pulmonary angiography and thromboendarterectomy during 1995 and 1996 were included. Thirty-four underwent helical CT angiography. Measurements of postoperative pulmonary vascular resistance were compared with preoperative imaging features and preoperative pulmonary vascular resistance. RESULTS: The best imaging indicators of a relatively high postoperative pulmonary vascular resistance were the extent of small vessel disease identified on CT angiograms as segments with abnormal perfusion but normal segmental arteries (p = 0.005) and the extent of central disease (p = 0.015). Combined with preoperative pulmonary vascular resistance, these features had a strong correlation with postoperative outcome (p = 0.0005). Segmental arterial disease seen on both conventional angiography and CT angiography correlated poorly with surgical outcome. CONCLUSION: In patients with chronic thromboembolic pulmonary hypertension, CT angiographic evidence of extensive central vessel disease and limited small vessel involvement indicates a favorable surgical outcome.

Adolescent↗
PubMed1999

Quantitation of emphysema with three-dimensional CT densitometry: comparison with two-dimensional analysis, visual emphysema scores, and pulmonary function test results.

PURPOSE: To compare lung densitometric measurements that use a three-dimensional (3D) reconstruction of the lungs with those obtained from analysis of two-dimensional (2D) computed tomographic (CT) images, visual emphysema scores, and data from pulmonary function tests. MATERIALS AND METHODS: Thoracic helical CT scans were obtained in 60 adult patients (35 with no visual evidence of emphysema and 25 with emphysema). The lungs were reconstructed as a 3D model on a commercial workstation, with a threshold of -600 HU. By analysis of histograms, the proportions of lung volumes with attenuation values below -950, -910, and -900 HU were measured, in addition to mean lung attenuation. These values were compared with lung densitometric results obtained from 2D CT images, visual emphysema scores, and data from pulmonary function tests. RESULTS: Quantitation of emphysema with 3D reconstruction was efficient and accurate. Correlation was good among densitometric quantitation with 3D analysis, that obtained with 2D analysis (r = 0.98-0.99), and visual scoring (r = 0.74-0.82). Correlation was reasonable between 3D densitometric quantitation and the diffusing capacity of the lungs for carbon monoxide (DLCO) (r = -0.57 to -0.64), total lung capacity (r = 0.62-0.71), forced expiratory volume in 1 second (FEV1) (r = -0.57 to -0.60), and the ratio of FEV1 to forced vital capacity (FVC) (r = -0.75 to -0.82). The visual CT quantitation of emphysema correlated best with DLCO (r = -0.82) and FEV1/FVC (r = -0.89). CONCLUSION: Lung densitometry with 3D reconstruction of helical CT data is a fast and accurate method for quantifying emphysema.

Absorptiometry, Photon↗
PubMed1999

Identifying the cause of unilateral hypoperfusion in patients suspected to have chronic pulmonary thromboembolism: diagnostic accuracy of helical CT and conventional angiography.

PURPOSE: To determine the prevalence of unilateral hypoperfusion in patients suspected to have chronic thromboembolism (CTE), to identify the most common cause of hypoperfusion, and to compare the accuracy of helical computed tomographic (CT) angiography with that of conventional angiography in helping to determine the cause. MATERIALS AND METHODS: Radionuclide lung scan reports showed asymmetric hypoperfusion in 47 of 410 consecutive patients referred because of suspected CTE. Twenty-seven patients had unilateral or predominantly unilateral perfusion abnormalities. Each pulmonary angiogram and CT angiogram in these patients was interpreted independently by two readers blinded to clinical information and surgical outcome. Surgical confirmation of the diagnosis was available in 39 of the 47 patients with asymmetric hypoperfusion. RESULTS: Unilateral (n = 11) or predominantly unilateral hypoperfusion (n = 16) was found in 6.6% (27 of 410 patients) of patients referred, and CTE was the most common cause. The accuracies of CT angiogram readers (reader 1, 83%; reader 2, 89%) were greater than those of conventional angiogram readers (reader 1, 73%; reader 2, 65%) for distinguishing CTE from other causes. CONCLUSION: Unilateral hypoperfusion occurred in 6.6% of our study population, most frequently because of CTE. CT angiography is an excellent diagnostic alternative to conventional angiography for distinguishing patients with CTE from those with other causes.

Adolescent↗
PubMed1998

Liver biopsy pathology in human immunodeficiency virus infection.

OBJECTIVES: To determine the hepatic changes in patients with human immunodeficiency virus (HIV) infection in Dublin and to assess the usefulness of liver biopsy in this condition. DESIGN: A consecutive series of liver biopsies was examined retrospectively and correlated with clinical findings. METHODS: A histological review was conducted of specimens from all patients who had undergone liver biopsy in a tertiary referral centre for HIV-infected patients in Dublin. RESULTS: Thirty-nine liver biopsies were studied from 36 patients. Thirty-one (86%) showed pathological changes. Non-specific changes were most frequent, followed by viral-induced chronic hepatitis (15 cases). Acute hepatitis was documented in five and cirrhosis in four cases. Five biopsies performed for pyrexia of unknown origin (PUO) or suspected tuberculosis showed granulomas. Organisms were rarely identified (2) and bile duct changes were uncommon. CONCLUSIONS: Liver biopsy was useful in detecting primary hepatic pathology and, in some cases, the cause of PUO, but not useful in detecting opportunistic infections despite their known presence in other organs.

Acute Disease↗
PubMed1997

Chronic thromboembolic pulmonary hypertension: the disease, the diagnosis, and the treatment.

Chronic thromboembolic pulmonary hypertension is a disease of unknown etiology, the diagnosis and treatment of which has changed dramatically in the past decade. Increased clinical awareness and recent developments in imaging techniques combine to promote earlier and less invasive diagnosis. Improved surgical thromboendarterectomy techniques and decreased perioperative mortality have enabled remarkable cures for most patients with this previously fatal condition. This article reviews current understanding of the disease process, imaging modalities used in diagnosis, and surgical treatment of patients with chronic thromboembolism.

Angiography↗
PubMed1997

Chronic thromboembolism: diagnosis with helical CT and MR imaging with angiographic and surgical correlation.

PURPOSE: To evaluate the accuracy of identification of central and segmental chronic thromboembolic disease on helical computed tomographic (CT) scans and on magnetic resonance (MR) images. MATERIALS AND METHODS: Radiologic findings in 55 patients suspected of having chronic thromboembolic pulmonary hypertension were analyzed; these included findings from angiography (n = 55), helical CT (n = 47), and MR imaging (n = 26). Forty patients underwent thromboendarterectomy. CT and MR images were independently interpreted by two readers for the presence of thromboembolic material in central and segmental vessels. Surgical findings and angiographic findings were the reference standards for disease in central and segmental vessels, respectively. RESULTS: Central vessel disease was determined more accurately with helical CT scans (accuracy of 0.79 for each of the two readers) than with angiograms (accuracy of 0.74) or with MR images (accuracy of 0.39 and 0.46 for two readers). Segmental vessel disease was also more accurately determined with CT scans (accuracy of 0.75 and 0.76 for two readers) than with MR images (accuracy of 0.61 and 0.57 for two readers). CONCLUSION: Helical CT is a useful alternative to conventional angiography for diagnosis of chronic thromboembolism but may not be sufficient for selecting candidates for surgery in all cases.

Aged↗
PubMed1997

Accuracy of MR angiography compared with radionuclide scanning in identifying the cause of pulmonary arterial hypertension.

OBJECTIVE: MR imaging has proven accurate in identifying patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, we know of no attempt to distinguish patients with CTEPH from patients with other causes of pulmonary arterial hypertension (PAH). Primary pulmonary hypertension (PPH) is the disease most frequently confused with CTEPH. We examined patients with CTEPH or PPH and control subjects to identify MR imaging features that might distinguish CTEPH from PPH, to compare the accuracy of MR angiography (MRA) with that of radionuclide scanning, and to determine the cardiac and pulmonary vascular measurements in these groups. SUBJECTS AND METHODS: T1-weighted and two-dimensional multiplanar spoiled gradient-recalled scans were obtained in 30 patients with CTEPH who had undergone conventional pulmonary angiography, 10 patients with PPH, and 13 control subjects with no known vascular disease. Ventilation-perfusion scans were available in all patients with CTEPH and in six of the 10 patients with PPH. The MR scans were assessed independently by two radiologists who evaluated the appearance of segmental vessels and noted the presence of mosaic perfusion. Cardiac chambers and pulmonary vessels were measured on T1-weighted spin-echo scans. RESULTS: The two radiologists used MR angiograms to reliably distinguish between patients with CTEPH and those with PPH. The accuracy of MR angiograms matched that of ventilation-perfusion scans (92%). On T1-weighted scans, the two radiologists used cardiac and pulmonary vascular measurements to distinguish patients with PAH from control subjects but failed to distinguish between patients with CTEPH and those with PPH. CONCLUSION: MRA is useful in distinguishing patients with CTEPH from those with PPH. In this population, MRA had an accuracy that was identical to that of radionuclide scanning. Vascular and cardiac measurements made on MR scans reliably identified patients with PAH but did not distinguish between patients with CTEPH and those with PPH.

Adult↗
PubMed1996

Magnetic resonance detection of acute pulmonary emboli in a canine model with pathologic correlation.

RATIONALE AND OBJECTIVES: The authors evaluated the accuracy of magnetic resonance (MR) imaging in depicting acute pulmonary emboli at the lobar, segmental, and subsegmental levels. METHODS: The authors induced 29 autologous emboli in five dogs and confirmed their location with angiography and anatomic dissection. MR images obtained with four sequences were independently evaluated by two radiologists to detect emboli in each vascular segment. Sensitivities, specificities, and accuracies were calculated at segmental and lobar levels. RESULTS: The fast short-tau inversion-recovery images provided the greatest conspicuity and highest overall accuracy (reader 1 = 74.3%, reader 2 = 80%). Accuracy of two-dimensional fast multiplanar spoiled gradient-recalled-echo images was limited by spatial resolution (reader 1 = 71.4%, reader 2 = 74.3%). The fast spin-echo T2-weighted and spin-echo T1-weighted sequences were intermediate in their depiction of acute emboli. Similar results were seen at the lobar level. CONCLUSION: MR images depict acute pulmonary embolism at the segmental and lobar levels with reasonable accuracy. Fast short-tau inversion-recovery sequences provided the greatest sensitivity and accuracy.

Acute Disease↗
PubMed1996

Detecting pulmonary abnormalities on magnetic resonance images in patients with usual interstitial pneumonitis: effect of varying window settings and gadopentetate dimeglumine.

RATIONALE AND OBJECTIVES: We examined the effect of varying window settings and contrast enhancement on detecting pulmonary abnormalities on magnetic resonance (MR) images in patients with usual interstitial pneumonitis (UIP). METHODS: HRCT scans and MR images from 10 patients with UIP were evaluated. T1-weighted MR images were obtained before and after administration of gadopentetate dimeglumine and were photographed at conventional windows and at windows chosen to increase the conspicuity of the lung parenchyma ("lung windows"). The four MR image configurations were mixed with the high-resolution computed tomography (HRCT) scans of these patients and randomized. Corresponding scan levels in each patient were evaluated conjointly by two thoracic radiologists for the presence of "honeycomb lung," ground-glass opacity, parenchymal bands, and reticular abnormalities. Lung signal intensity in areas containing ground-glass signal intensity was measured on MR images using regions of interest. RESULTS: The administration of gadopentetate dimeglumine significantly improved the detection of honeycomb lung on scans photographed at lung windows, but it did not significantly influence the detection of ground-glass abnormalities. The use of lung windows improved the detection of ground-glass abnormalities for both enhanced and unenhanced scans, but lung windows improved the detection of honeycomb lung only for enhanced scans. All MR image configurations were insensitive compared with HRCT scans for detecting parenchymal bands and reticular abnormalities. There was a good correlation between measured lung signal intensity and visual ground-glass profusion score. CONCLUSION: The visibility of pulmonary abnormalities on MR images of patients with UIP is limited compared with that of HRCT scans. The improved visibility of some parenchymal abnormalities after intravenous administration of gadopentetate dimeglumine and with the use of lung windows is insufficient to warrant their routine use in thoracic MR imaging.

Aged↗
PubMed1996

Accuracy of contrast-enhanced magnetic resonance angiography in chronic thromboembolic disease.

RATIONALE AND OBJECTIVES: We evaluated the accuracy of contrast-enhanced magnetic resonance (MR) angiography in demonstrating the findings of chronic pulmonary thromboembolism (CPTE) compared with conventional pulmonary angiography. METHODS: We examined 18 patients with CPTE proved by conventional pulmonary angiography and 16 healthy control patients. T1-weighted and single-breathhold, two-dimensional multiplanar spoiled gradient-recalled pulmonary images were obtained after injection of gadopentetate dimeglumine. Images were interpreted independently by two radiologists. RESULTS: All patients with CPTE were identified on MR angiography images by both readers. Sensitivity and specificity for MR angiography in diagnosing abnormal segments were 76% and 95% for reader 1 and 68% and 93% for reader 2, respectively. Sensitivity and specificity for MR angiography in depicting abnormal lobes were 83% and 96% for reader 1 and 82% and 93% for reader 2, respectively. Interobserver agreement was high; kappas for abnormal segments and abnormal lobes were .72 and .84, respectively. The T1-weighted spin-echo images demonstrated a mosaic signal intensity pattern in all patients with CPTE. CONCLUSION: Contrast-enhanced MR angiography accurately depicts abnormal segments and lobes in occlusive vascular disease and clearly distinguishes between patients with CPTE and those with healthy lungs.

Chronic Disease↗
PubMed1996

Accuracy of high-resolution CT in identifying chronic pulmonary thromboembolic disease.

OBJECTIVE: The aims of this study were to determine the reliability of the high-resolution CT (HRCT) appearance of the lung parenchyma in distinguishing patients with chronic pulmonary thromboembolism (CPTE) from those with other pulmonary diseases and to compare HRCT with radionuclide scanning. SUBJECTS AND METHODS: Sixty-seven patients for whom HRCT scans were available for review were included in the study. Twenty-eight had proven pulmonary arterial hypertension (PAH), 17 cases of which were caused by CPTE, and 39 had other pulmonary abnormalities. Diagnosis based on the HRCT appearance was attempted by two radiologists, who independently evaluated pulmonary parenchyma for a mosaic pattern of variable attenuation, for a measurable disparity in the size of pulmonary vessels, and for the presence of peripheral scars. HRCT findings were compared with radionuclide scan findings and pulmonary angiography findings. RESULTS: For both readers (readers 1 and 2), sensitivity (94% and 100%, respectively) and specificity (96% and 98%, respectively) were high for distinguishing patients with CPTE from patients with other pulmonary abnormalities, including those with nonthromboembolic PAH. The average ratios of segmental vessel size were 2.2 for patients with CPTE and 1.1 for those with nonthromboembolic diseases. Mosaic attenuation was identified in all patients with CPTE but was also seen in 22% (reader 1) and 14% (reader 2) of patients with no evidence of CPTE. Radionuclide scans revealed a high probability for pulmonary emboli for all but one patient with CPTE but also revealed a high probability for three patients who had no emboli. CONCLUSION: HRCT findings of disparity in the size of segmental vessels and a mosaic pattern of variable attenuation reliably distinguished patients with CPTE from those with nonthromboembolic PAH and from those with other pulmonary abnormalities. In addition, HRCT was more specific than radionuclide scanning in identifying patients with CPTE.

Adolescent↗
PubMed1994

Computed tomography assessment of splenic size as a predictor of splenic weight and disease involvement in laparotomy staged Hodgkin's disease.

PURPOSE: To evaluate how well splenic size predicts the risk of splenic Hodgkin's disease and to assess how accurately splenic dimensions on computerized tomographic scans predict spleen size and involvement by Hodgkin's disease. METHODS AND MATERIALS: Splenic weights were obtained from laparotomies performed on 897 patients who presented with Hodgkin's disease and were compared with histologic involvement using logistic regression. Splenic dimensions were measured from preoperative computerized tomographic scans in 94 of these patients, and unidimensional splenic measurements [length (L), width (W), thickness (T)] and their products were compared with splenic weight at laparotomy using linear regression. RESULTS: Hodgkin's disease involved 42% of the spleens at laparotomy and 31% of those assessed by computerized tomography. Splenic weight averaged 198 +/- 5 g (range 40-2000 g). Weight and involvement were greater with "unfavorable" histologies (mixed cellularity, lymphocyte depletion, and unclassified Hodgkin's disease: 229 +/- 12 g; 62.7% involved) than with "favorable" histologies (nodular sclerosing, lymphocyte predominant, and interfollicular Hodgkin's disease: 191 +/- 5 g; 37.8% involved). Splenic weight was the strongest independent risk factor correlated with Hodgkin's disease in univariate and multivariate analyses in all patients and the only identifiable univariate risk factor among those with computerized tomographic scans. For most patients, however, splenic weight poorly predicted involvement: The probability of involvement never fell below 20% and exceeded 80% when splenic weight exceeded 270 g with unfavorable histologies or 685 g in favorable histologies. Spleens of average weight had a probability of involvement of 36% with favorable histologies, 70% with unfavorable histologies. Unidimensional measurements of the spleen on computed tomography correlated poorly with splenic weight, but their product correlated well (Correlation coefficients: L: 0.73; W: 0.65; T: 0.78; [0.344485 x L x W x T]: 0.94). CONCLUSIONS: Splenic weight is the strongest factor correlating with the risk of splenic involvement by Hodgkin's disease and can be accurately estimated from three-dimensional measurements on computed tomographic scans, but not from unidimensional measurements. However, splenic weight is not a sensitive predictor of involvement of the spleen by Hodgkin's disease. Therefore, treatment approaches to Hodgkin's disease must be based upon intermediate risks of splenic involvement for most clinically staged patients.

Adolescent↗
PubMed1994

Single breath-hold pulmonary magnetic resonance angiography. Optimization and comparison of three imaging strategies.

RATIONALE AND OBJECTIVES: Ultrafast gradient-recalled-echo techniques for obtaining high-quality pulmonary magnetic resonance angiograms within a single breath-hold were optimized. METHODS: Fourteen subjects were imaged with both the body coil and a phased-array surface coil, using three gradient-recalled-echo pulse sequences: 1) two-dimensional sequential; 2) two-dimensional interleaved; and 3) volumetric acquisitions. Image quality was assessed with varied flip angle, receiver bandwidth, slice thickness/number, and matrix size. Cardiac compensation diminished ghost artifacts in the interleaved sequence. Individual sagittal sections and maximum intensity projections were reviewed. RESULTS: Pulmonary magnetic resonance angiograms acquired with volumetric and two-dimensional interleaved gradient-recalled-echo pulse sequences benefit greatest from intravenous gadolinium and result in greater pulmonary arterial visualization than traditional time-of-flight techniques. Phased-array coils result in improved vessel detection. CONCLUSIONS: High-quality breath-held pulmonary magnetic resonance angiography can be obtained with an intravenous contrast-enhanced gradient-recalled-echo acquisition; however, image quality is dependent on the pulse sequence.

Adult↗
PubMed1994

Frequency and management of pneumothoraces in heart-lung transplant recipients.

PURPOSE: To determine the frequency and describe the clinical relevance of simultaneous bilateral pneumothoraces in heart-lung transplant recipients. MATERIALS AND METHODS: The chest radiographs in 72 consecutive heart-lung transplant recipients were retrospectively reviewed. The study group consisted of 15 patients with a pneumothorax that occurred after removal of surgically placed drainage tubes and subsequent complete expansion of both lungs. RESULTS: Simultaneous bilateral pneumothoraces occurred in six patients (40%); 10 episodes of unilateral pneumothorax occurred in nine patients (60%). Causes of pneumothoraces included transthoracic fine-needle biopsy (n = 5), bronchoscopic biopsy (n = 3), placement of a central venous catheter (n = 3), and thoracentesis (n = 3); no cause was found in two cases. CONCLUSION: Physicians who perform transthoracic interventions in this patient population should be aware of the likelihood of persistent pleural communications and the possibility of potentially life-threatening bilateral pneumothoraces.

Adolescent↗
PubMed1994

Thoracic CT images: effect of lossy image compression on diagnostic accuracy.

PURPOSE: To evaluate the effects of lossy image (noninvertible) compression on diagnostic accuracy of thoracic computed tomographic images. MATERIALS AND METHODS: Sixty images from patients with mediastinal adenopathy and pulmonary nodules were compressed to six different levels with tree-structured vector quantization. Three radiologists then used the original and compressed images for diagnosis. Unlike many previous receiver operating characteristic-based studies that used confidence rankings and binary detection tasks, this study examined the sensitivity and predictive value positive scores from nonbinary detection tasks. RESULTS: At the 5% significance level, there was no statistically significant difference in diagnostic accuracy of image assessment at compression rates of up to 9:1. CONCLUSION: The techniques presented for evaluation of image quality do not depend on the specific compression algorithm and provide a useful approach to evaluation of the benefits of any lossy image processing technique.

Humans↗
PubMed1994

Chronic pulmonary thromboembolism: detection of regional hypoperfusion with CT.

PURPOSE: To study the relationship of regional hypoperfusion and areas of decreased lung attenuation on computed tomographic (CT) scans of patients with chronic pulmonary thromboembolism. MATERIALS AND METHODS: Preoperative CT scans of five patients (four men and one woman, aged 29-72 years) with chronic pulmonary thromboembolism were reviewed and compared with axial single photon emission CT (SPECT) perfusion scans obtained at similar levels. Regions of varying attenuation and perfusion were scored on a three-point scale. RESULTS: In the five patients, 198 regions were identified. Of 176 abnormal regions at SPECT, 133 were abnormal at CT (sensitivity, 75.6%). Eleven of 22 regions interpreted as normal at SPECT were judged to have normal attenuation at CT (specificity, 50%). The overall accuracy of CT for detecting areas of hypoperfusion was 72.7% (P = .011). CONCLUSION: A mosaic pattern of lung attenuation at CT is a sign of variable regional perfusion and may suggest chronic pulmonary thromboembolism as a cause for pulmonary hypertension.

Chronic Disease↗