Poonam Batra

Pulmonary dysfunction in advanced liver disease: Frequent occurrence of an abnormal diffusing capacity

PURPOSE Abnormalities in pulmonary function have been reported in association with chronic liver disease of varied etiology. The aim of this study was to better define the frequency and nature of these abnormalities in patients who were being evaluated for liver transplantation. PATIENTS AND METHODS We performed a battery of pulmonary function tests and chest radiographs in 116 consecutive patients (50 men, 66 women; aged 19 to 70 years, mean 44.6 years) with severe advanced liver disease who were hospitalized specifically for evaluation for possible orthotopic liver transplantation and were able to perform technically satisfactory tests. In 17 patients, quantitative whole-body technetium-99m macroaggregated albumin perfusion scanning was also performed for assessment of possible right-to-left shunting through intrapulmonary vascular dilatations. RESULTS The most commonly affected test of lung function was the single-breath diffusing capacity for carbon monoxide (DLCO), which was abnormal in 48%, 45%, and 71% of patients who never smoked, former smokers, and current smokers, respectively. Ventilatory restriction was noted in 25% of all patients, airflow obstruction (reduced ratio of forced expiratory volume in 1 second to forced vital expiratory volume in 1 second to forced vital capacity) in only 3%, and a widened alveolar-arterial oxygen gradient in 45%. Diffusion impairment was accompanied by a restrictive defect in only 35% of the patients and by an abnormally widened alveolar-arterial oxygen gradient in 60%. When diffusion impairment was accompanied by an oxygenation defect, it was also associated with a significantly increased right-to-left shunt fraction (mean 24.9%) assessed from quantitative whole-body perfusion imaging. On the other hand, isolated diffusion impairment unaccompanied by significant hypoxemia (noted in approximately a third of the patients with a reduced DLCO) was not associated with evidence of significant intrapulmonary shunting (mean right-to-left shunt fraction 6.7%). CONCLUSIONS Most patients with advanced liver disease have one or more types of abnormality in lung function, a reduced DLCO being the single most common functional defect. Mechanisms accounting for the abnormality in gas transfer may include intrapulmonary vascular dilatations, diffuse interstitial lung disease, pulmonary vaso-occlusive disease, and/or ventilation-perfusion imbalance.

Automated classification of lung bronchovascular anatomy in CT using AdaBoost

Lung CAD systems require the ability to classify a variety of pulmonary structures as part of the diagnostic process. The purpose of this work was to develop a methodology for fully automated voxel-by-voxel classification of airways, fissures, nodules, and vessels from chest CT images using a single feature set and classification method. Twenty-nine thin section CT scans were obtained from the Lung Image Database Consortium (LIDC). Multiple radiologists labeled voxels corresponding to the following structures: airways (trachea to 6th generation), major and minor lobar fissures, nodules, and vessels (hilum to peripheral), and normal lung parenchyma. The labeled data was used in conjunction with a supervised machine learning approach (AdaBoost) to train a set of ensemble classifiers. Each ensemble classifier was trained to detect voxels part of a specific structure (either airway, fissure, nodule, vessel, or parenchyma). The feature set consisted of voxel attenuation and a small number of features based on the eigenvalues of the Hessian matrix (used to differentiate structures by shape). When each ensemble classifier was composed of 20 weak classifiers, the AUC values for the airway, fissure, nodule, vessel, and parenchyma classifiers were 0.984+/-0.011, 0.949+/-0.009, 0.945+/-0.018, 0.953+/-0.016, and 0.931+/-0.015, respectively. The strong results suggest that this could be an effective input to higher-level anatomical based segmentation models with the potential to improve CAD performance.

THE EFFECT OF IRREVERSIBLE IMAGE COMPRESSION ON DIAGNOSTIC ACCURACY IN THORACIC IMAGING

RATIONALE AND OBJECTIVES.Digital image compression reduces the storage requirements and network traffic on picture archiving and communications systems. Full-frame bitallocation (FFBA) is an irreversible image-compression method based on the discrete cosine transform that provides for high compression ratios with a high degree of image fidelity. METHODS.One hundred twenty-two posteroanterior chest radiographs were obtained on patients in an ambulatory patient setting, including 30 cases of interstitial lung disease, 45 images containing combinations of lung nodules (N=37) or mediastinal masses (N=39), and 47 normal images containing none of the pathology for which we were testing. The images were digitized (nominal 2 K X 2 K X 12-bit resolution), printed on a 35 x 35-cm hard copy format, and compressed at an approximate compression ratio of 20:1. Observer performance tests were conducted with five radiologists using receiver operating characteristic analysis on digitized uncompressed and compressed hard copy images. RESULTS.There were no significant differences between the two display conditions for the detectability of any of the thoracic abnormalities. CONCLUSIONS.Our preliminary results suggest that irreversible image compression at ratios of 20:1 may be acceptable for use in digital thoracic imaging.

The fat embolism syndrome

The clinical fat embolism syndrome consisting of progressive pulmonary insufficiency, cerebral disfunction, and petechiae is rare. Following severe skeletal trauma, fat droplets appear in the circulating blood and embolize the capillaries of the lungs and other organs. Whether fat droplets are of mechanical or chemical origin remains controversial. These fat droplets cause mechanical occlusion of lung capillaries followed by chemical changes associated with hydrolysis of the neutral fat to free fatty acids. The free fatty acids produce a toxic and inflammatory reaction resulting in pulmonary edema, hemorrhage, and micro-atelectasis. The clinical and radiographic abnormalities appear after an initial latent period of 12 to 72 hours. The chest radiographic findings are nonspecific and consist of bilateral patchy or diffuse alveolar and interstitial lung densities. With aggressive management the survival has markedly improved, and mortality is now rare.

MR imaging of the thorax: a comparison of axial, coronal, and sagittal imaging planes

We performed direct multisection coronal and sagittal magnetic resonance (MR) images in addition to axial images to determine the value and limitations of coronal and sagittal planes compared with axial planes. Ninety-four MR examinations of the thorax were performed with a 0.3 T permanent magnet system (Fonar) by spin echo technique. The MR axial images were found superior to coronal in demonstrating prevascular adenopathy (one case), pretracheal nodes (nine cases), left paraaortic nodes (three cases), subcarinal nodes (three cases), and small pleural effusions (three cases). The coronal or sagittal planes were better to determine relationship of a mass at the lung apex (five cases) or an abnormality at the lung base (five cases). The anteroposterior displacement or compromise of great vessels and bronchi was best displayed on the axial plane whereas craniocaudal displacement of above structures was best seen on the coronal plane. The axial images were found most informative and we suggest that they be performed routinely. Coronal or sagittal planes may be added in selected cases.

Pulmonary Coccidioidomycosis: Pictorial Review of Chest Radiographic and CT Findings

Pulmonary coccidioidomycosis is a fungal disease endemic to the desert regions of the southwestern United States, Mexico, Central America, and South America. The incidence of reported disease increased substantially between 1998 and 2011, and the infection is encountered beyond the endemic areas because of a mobile society. The disease is caused by inhalation of spores of Coccidioides species. Individuals at high risk are those exposed to frequent soil aerosolization. The diagnosis is established by direct visualization of mature spherules by using special stains or cultures from biologic specimens. Serologic testing of anticoccidioidal antibodies is used for diagnosis and treatment monitoring. The infection is self-limited in 60% of cases. When the disease is symptomatic, the lung is the primary site of involvement. On the basis of clinical presentation and imaging abnormalities, pulmonary involvement is categorized into acute, disseminated, and chronic forms, each with a spectrum of imaging findings. In patients with acute disease, the most common findings are lobar or segmental consolidation, multifocal consolidation, and nodules. Adenopathy and pleural effusions are also seen, usually in association with parenchymal disease. Disseminated disease is rare and occurs in less than 1% of patients. Pulmonary findings are miliary nodules and confluent parenchymal opacities. Acute respiratory distress syndrome is an infrequent complication of disseminated disease. The acute findings resolve in most patients, with chronic changes developing in approximately 5% of patients. Manifestations of chronic disease include residual nodules, chronic cavities, persistent pneumonia with or without adenopathy, pleural effusion, and regressive changes. Unusual complications of chronic disease are mycetoma, abscess formation, and bronchopleural fistula. Patients in an immunocompromised state, those with diabetes mellitus, pregnant women, and those belonging to certain ethnic groups may show severe, progressive, or disseminated disease.

Efficacy and complications of transthoracic needle biopsy of lung in patients with Pneumocystis carinii pneumonia and AIDS.

Transthoracic needle biopsy of lung was performed under fluoroscopic guidance in 16 patients with AIDS or suspected AIDS for diagnosing 18 episodes of possible P carinii infection. Diagnostic information was obtained in 15 of 18 cases. P carinii (10) and other infections agents (5) were diagnosed by TNB. The complications were pneumothorax in 44% (17% requiring chest tube drainage) and minor hemoptysis in 11%. Our incidence of pneumothorax following TNB in patients with diseases other than AIDS is 17% with 4.8% requiring chest tube drainage. Although TNB under fluoroscopic guidance is a cost-effective, rapid procedure with a high diagnostic yield, it is frequently complicated by pneumothorax in AIDS patients with diffuse pulmonary disease. This procedure should therefore only be performed in AIDS patients when transbronchial biopsy has failed to provide the diagnosis and prior to considering such patients for open lung biopsy.

MR imaging of aneurysm of an aberrant right subclavian artery.

Magnetic resonance (MR) imaging was performed for evaluation of a right paramediastinal mass in an asymptomatic 84-year-old woman. An aneurysm of an aberrant right subclavian artery was diagnosed. This rare complication of a common congenital anomaly and the use of MR in evaluation is discussed.

A Curriculum in Cardiothoracic Radiology for Medical Students, with Goals and Objectives

The Liaison Committee on Medical Education is the accrediting body for medical education programs leading to the MD degree in the United States and Canada. According to the Committee’s accreditation standards (1), “The curriculum must provide grounding in the body of knowledge represented in the disciplines that support the fundamental clinical subjects, for example, diagnostic imaging and clinical pathology.” In a survey of 119 directors of medical student education in radiology, 46 (39%) responded to questions regarding the teaching of radiology to medical students at their institution (2). A core radiology clerkship was required at 13 (29%) of 46 schools responding and was an elective at 33 (72%) (2). The number of schools with a required radiology clerkship has not changed since 1994 (3). The clerkship is given in the 3rd year at 12 (26%) of 46 schools, in the 4th year at 20 (44%), and in either the 3rd or 4th year at 14 (30%) (2). Twenty-six (57%) of 46 programs have computers in the department that students use during the course, usually shared with residents. Reported simultaneously with these survey results were results from a second survey of directors of medical student education, in which 69 (50%) of 139 responded (2). Six (9%) of 69 responding programs directed the medical school’s gross anatomy course, and 14 (20%) taught some portion of the course. A telephone survey (4) showed that a formal dedicated radiology clerkship was a graduation requirement in only five of the 16 top-ranked medical schools in a U.S. News & World Report ranking (Cornell, Duke, Harvard, University of California at San Francisco, and University of California at Los Angeles) (5). In contrast, a survey of 322 nonradiologist physicians showed that 87% believed formal radiology instruction should be mandatory (6). Radiology can be taught to medical students through an integrated curriculum, an independent curriculum, or a combination of the two. In an integrated curriculum, radiology faculty provide radiology instruction to medical students rotating through a nonradiology course or a course that is jointly sponsored by radiology and nonradiology departments. For example, radiologists teach projectional and cross-sectional imaging to medical students enrolled in a gross anatomy course. Radiologists may give a series of imaging lectures related to topics covered in a required medicine clerkship. Collaboration can occur when radiology faculty participate in required introductory courses that expose students early in medical school to physical examination techniques, history taking, and writing patient notes. These courses have various titles, such as “Introduction to Clinical Medicine” or “Patient, Doctor, and Society.” Radiology faculty can provide correlative imaging instruction in most required courses. The Alliance of Medical Student Educators in Radiology is a group associated with the Association of University Radiologists whose purpose is to promote radiology as an essential component of the medical student curricuAcad Radiol 2001; 8:1247–1251

Diagnosis of peripheral pulmonary emboli by MR imaging: an experimental study in dogs

The peripheral pulmonary arteries of 5 dogs were embolized with boiled autologous clots via the external right jugular vein. Angiography determined the location and approximate size of the emboli in the peripheral pulmonary arteries. With spin echo techniques, transverse axial magnetic resonance (MR) images (0.3 T, 12.77 MHz) were obtained in each animal from apex to thorax base, on a permanent magnet scanner. The sensitivity of MR imaging was assessed to detect these clots and to determine their size and location. In 2 dogs, scans were also obtained before embolization in order to exclude possible artifactual areas of increased signal. Fourteen out of 19 emboli were identified on the MR scans as areas of increased signal. Their diameter measured a minimum of 2.7 mm matching the filling defects seen on the angiograms. There were three false positive emboli on MR probably related to slow blood flow in the inferior vena cava. There were 9 false negative emboli on MR. The increased MR signal seen in dogs with pulmonary emboli results from the embolus itself and from slow blood flow distal to the obstructive embolus.