Lymph node enlargement in pulmonary arterial hypertension due to chronic thromboembolism.

The aim of this study was to determine the prevalence and location of enlarged mediastinal and hilar lymph nodes in patients with pulmonary arterial hypertension (PAH) due to chronic pulmonary thromboembolism (CPTE) and to identify possible causes. Thoracic CT images of 85 patients (43 men and 42 women, aged 18-80 years) with PAH in whom CPTE was confirmed at surgery (n = 75) or angiography and angioscopy (n = 10) were evaluated by two thoracic radiologists to determine the presence, size and location of lymph nodes more than 1 cm in the short axis. The presence of pleural and pericardial effusions and parenchymal abnormalities were also noted. Enlarged lymph nodes were identified in 38 patients (44.7%), including 11 with possible causes of lymphadenopathy other than CPTE. In the 27 patients with CPTE alone, 67 enlarged lymph nodes were detected (average 2.5 per patient). Nine patients had three or more enlarged lymph nodes. The most common sites of lymph node enlargement were American Thoracic Society locations 7 (n = 13), 6 (n = 10), 11L (n = 9), 10R (n = 7) and 4R (n = 7). Pleural and pericardial effusions were more common in patients with CPTE who also had lymphadenopathy than in the group with no lymphadenopathy (P < 0.05). Lymph node enlargement is common in patients with PAH caused by CPTE. The frequent association of lymphadenopathy with pleural and pericardial effusions suggest a possible pathophysiological mechanism of increased lymphatic flow caused by right heart failure.

A left atrial pseudomass: potential pitfall at thoracic MR imaging.

We frequently observed a nodular soft-tissue structure in the region of the left atrium anterior to the orifice of the left inferior pulmonary vein on MR scans of the chest. To assess its morphologic characteristics and appearance, chest MR scans obtained in 49 patients were reviewed. ECG-gated conventional spin-echo T1-weighted and fast spin-echo (FSE) T2-weighted sequences were used. The location, morphology, and appearance of this soft-tissue structure was evaluated by two radiologists during one consensus reading. The pseudomass in the region of the left atrium was identified on the T1-weighted images in 25 of 49 patients. The structure was also identified on FSE T2-weighted images in 6 of these patients. On the T1-weighted images, its appearance was either linear (54%) or nodular (46%). In conclusion, a nodular soft-tissue mass anterior to the orifice of the left inferior pulmonary vein into the left atrium is a frequent finding on chest MR scans and should not be confused with an intra-atrial mass. Careful evaluation of the regional anatomy identifies this structure as extraluminal and helps to avoid misinterpretation of an intracardiac mass.

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.

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.

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.

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.

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.

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.

Tree-structured vector quantization of CT chest scans: image quality and diagnostic accuracy.

The authors apply a lossy compression algorithm to medical images, and quantify the quality of the images by the diagnostic performance of radiologists, as well as by traditional signal-to-noise ratios and subjective ratings. The authors' study is unlike previous studies of the effects of lossy compression in that they consider nonbinary detection tasks, simulate actual diagnostic practice instead of using paired tests or confidence rankings, use statistical methods that are more appropriate for nonbinary clinical data than are the popular receiver operating characteristic curves, and use low-complexity predictive tree-structured vector quantization for compression rather than DCT-based transform codes combined with entropy coding. The authors' diagnostic tasks are the identification of nodules (tumors) in the lungs and lymphadenopathy in the mediastinum from computerized tomography (CT) chest scans. Radiologists read both uncompressed and lossy compressed versions of images. For the image modality, compression algorithm, and diagnostic tasks the authors consider, the original 12 bit per pixel (bpp) CT image can be compressed to between 1 bpp and 2 bpp with no significant changes in diagnostic accuracy. The techniques presented here for evaluating image quality do not depend on the specific compression algorithm and are useful new methods for evaluating the benefits of any lossy image processing technique.

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.

47-year-old woman with six-week history of lower extremity weakness and eosinophilia.

This discussion was selected from the Department of Medicine Morbidity and Mortality Conference held at the Stanford University Medical Center, Stanford, California, on January 9, 1991. The editor of the conference is Philip C. Lee, MD, Chief Resident, Department of Medicine.

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.

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.

MR evaluation of chest wall involvement in malignant lymphoma.

Chest CT and magnetic resonance (MR) examinations of 28 patients with newly diagnosed or recurrent lymphoma involving the mediastinum were retrospectively evaluated for evidence of chest wall involvement. Computed tomography demonstrated seven sites of chest wall involvement in four patients; whereas MR demonstrated 14 sites in seven patients, including all sites shown by CT. Eight chest wall lesions were located in the extranodal soft tissues (three sites were contiguous with anterior mediastinal lymphadenopathy; three sites were contiguous with pleural/parenchymal disease; and one each involved the breast and multiple vertebral bodies). Six sites involved lymph nodes in the interpectoral (n = 4), submammary (n = 1), and infraspinatus (n = 1) areas. Lesion conspicuity in the chest wall was better on T2- than T1-weighted sequences and was best on short inversion time inversion recovery. Detection of chest wall lymphoma may alter staging; when present in this group of patients, it influenced management in two of the seven patients.

Pneumocystis carinii pneumonia: CT and HRCT observations.

We examined the chest radiography, CT, and high resolution CT (HRCT) of 14 patients with proven Pneumocystis carinii pneumonia. We compared the radiographic and HRCT patterns of abnormal lung parenchyma with histologic sections obtained in those 11 patients who had had transbronchial lung biopsies. Diffuse bilateral perihilar airspace disease was the most common radiographic pattern. Both CT and HRCT showed "ground glass" opacity in the lungs, through which the vessels remained visible in all patients. No enlarged lymph nodes or pleural effusions were seen in patients without associated lymphoproliferative disorders.

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.