A systematic approach to interpretation of heterogeneous lung attenuation on computed tomography of the chest.

Computed tomography (CT) chest is widely used as an adjunct to clinical examination and pulmonary function tests in the evaluation of unexplained dyspnoea. In such patients, heterogeneous lung attenuation is a common finding on CT. Heterogeneous lungs can be caused by varying regional aeration, varying regional perfusion, and ground glass opacities (GGO) representing airspace or interstitial pathology. It does not serve the referring clinicians or the patients well if the radiology report simply mentions the heterogeneity of the lungs without due analysis of the cause of heterogeneity and a meaningful differential diagnosis. Therefore, it is imperative for the radiologist and the treating pulmonologist to have an in-depth understanding of the pathogenesis of pulmonary heterogeneity. This, in conjunction with clinical data, can narrow the differential diagnosis or, at times, lead to specific diagnoses. The purpose of this review is to familiarize readers with the CT representation of heterogeneities in aeration and perfusion of the lung, relate patterns of GGO to underlying pathology, and provide illustrative case studies highlighting the radiological approach to heterogeneous lungs.

Systematic survey of discrepancy rates in an international teleradiology service.

International teleradiology services (ITS) to the United States are based on the principle of deploying American board-certified radiologists across global time zones to optimally distribute the workload. While errors may be reduced by circumventing the traditional night call, there is limited evidence on the actual error rates of teleradiology groups. We have a comprehensive quality assurance (QA) process in our practice, which includes a review of discrepancies between preliminary reports and the final reports by the on-site radiologists. We analyzed the discrepancy QA data to determine the error rates. Archived QA data for 126,449 cases over a period of 1 year (2008) were analyzed for the discrepancy rate, nature of errors, and possible contributory factors. The scores ranged from 0 (no error) to 5 (clinically significant in the acute setting) based on the level of clinical significance. A novel modified Lorenz plot was used to estimate the degree of underreporting and to estimate the true error rate. An internal review of 200 cases was performed to validate the findings. Of the total, there was a total of 227 confirmed errors (0.18%, 95% CI, 0.16 to 0.20). Of these, the majority were levels 2 and 3 (minor error and error of long-term significance but not in the acute setting). Even after correction for underreporting, error rates were less than 1% for clinically significant errors. ITS is associated with very low rates of clinically significant errors. Due to limited feedback, particularly for minor errors, an internal review is important.

CT and MR imaging findings of malignant cardiac tumors.

This article reviews CT and MRI features of malignant cardiac and pericardial tumors, most of which originate from the lung, breast, melanoma, leukemia, or lymphoma through lymphatic, hematogenous, transvenous, and direct pathways. Although echocardiography establishes the diagnosis in most cases, CT and MRI provide additional physical, spatial, and functional information that further aids the evaluation of metastases. For instance, CT provides superior resolution for detecting calcification or fat, while MRI with its direct multiplanar ability more completely characterizes the heart, pericardium, mediastinum, and lungs. MRI also helps elucidate the pathophysiological effects of these tumors on cardiac function through gated cine-loop sequences. Beyond tumor characterization, both modalities can help confirm diagnosis through the addition of contrast, which helps distinguish tumor from myocardium, thrombus, and blood flow artifact. Ultimately, MRI best facilitates surgical planning and posttreatment follow-up in large part because of its unparalleled ability to locate and delimit these tumors.

CT and MR imaging findings of benign cardiac tumors.

This imaging review describes the appearance of benign cardiac tumors on CT and MRI. Although rare, benign tumors outnumber their primary malignant counterparts three to one. Since mortality varies directly with invasion, identifying the neoplasm at an early stage helps focus treatment, especially in benign cases, which generally respond well to surgical resection. In adults and children, myxomas and rhabdomyomas, respectively, represent the most common benign tumors, which can be grouped into tissue-specific subtypes, such as rhabdomyomas, fibromas, lipomas, teratomas, etc. Besides their variable prevalence in particular age groups, these tumors also differ with regard to their gender predilection, location, and number. For example, myxomas appear predominantly in women and generally as a solitary mass in the left or right atrium, whereas rhabdomyomas present equally in boys and girls and chiefly as multiple masses in the ventricles. Despite their differences, however, both types share an association with heritable syndromes like the Carney complex for myxomas and tuberous sclerosis for rhabdomyomas. As with all cardiac tumors, echocardiographic findings usually suggest the initial diagnosis but cross-sectional imaging with CT and MRI can help resolve diagnostically challenging cases. For example, with its direct multiplanar capability, excellent contrast resolution, and large field of view, MRI permits a detailed examination of the entire mediastinum, helping to rule out an equivocal mass on echocardiography. Through dynamic techniques, MRI, in addition to morphologic characterization, can depict the pathophysiological effects of these tumors, for instance, with regard to myocardial contraction, valvular function, or blood flow.

Imaging findings of expansile lesions of the thymus.

The purpose of this article is to review the imaging findings of the different expansile lesions of the thymus. Almost 50% of all mediastinal masses are located in the anterior mediastinum. The thymus is the most common site of origin of these masses. Several kinds of lesions can arise from this gland because it derives from the three embryonic germ cell layers. Primary neoplasms of the thymus are thymoma, thymolipomas, carcinoma, carcinoid, primary germ cell tumors, and lymphoma. The latter can also involve the organ in a secondary fashion. Other lesions that cause thymic enlargement and that can be confused with neoplasia are thymic cysts and thymic hyperplasia. Even though anterior mediastinal masses are first found on conventional radiographs, computed tomography and magnetic resonance are very useful additional studies for assessing the origin and extension of these masses. The basic concepts regarding embryology, anatomy, and histology relevant for the differential diagnosis of an enlarged thymic gland are also described.

Tracheobronchopathia osteochondroplastica: helical CT findings in 4 cases.

Tracheopathia osteochondroplastica is an uncommon abnormality of the cartilaginous tracheal wall, characterized by the presence of osteocartilaginous calcified nodules within the submucosa, with variable degree of diffuse tracheal narrowing. Imaging findings in CT are characterized by the presence of calcified nodular densities protruding into the tracheal lumen, with an abnormally irregular tracheal morphology and often decreased lateral diameter. This can extend to the proximal main stem bronchi. CT is the imaging modality of choice in this entity. The clinical manifestations, as well as the imaging findings, in 4 cases are reviewed.

Dual-energy digital subtraction chest radiography: technical considerations.

In the evaluation of asbestos-related pulmonary and pleural abnormalities, conventional chest radiography has been shown to have a low sensitivity for the detection of lung nodules and subtle interstitial disease. Pleural plaques may simulate pulmonary nodules, and interstitial processes can be masked by adjacent pleural abnormalities. Dual-energy digital subtraction chest radiography may enable investigators to characterize asbestos-related pulmonary and pleural abnormalities with greater accuracy. "Soft-tissue" images, designed to remove pleural calcifications, may allow for better evaluation of the lung parenchyma. "Bone" images, designed to remove soft-tissue structures, may enhance the detection of pleural calcifications. In this pictorial essay we illustrate the methods, technical considerations, and limitations of dual-energy digital subtraction chest radiography performed with global subtraction weighting factors.