Eric J. Stern

CT mosaic pattern of lung attenuation: etiologies and terminology.

Areas of variable lung attenuation forming a “mosaic pattern” are occasionally seen on computed tomography (CT) or high-resolution CT (HRCT) images of the lungs. This CT mosaic pattern of lung attenuation is a nonspecific finding that can reflect the presence of vascular disease, airway abnormalities, or ground-glass interstitial or air-space infiltrates. However, it is often possible to distinguish among these categories. In small airways disease and pulmonary vascular disease, the pulmonary vessels within the lucent regions of lung are small relative to the vessels in the more opaque lung. In infiltrative diseases, the vessels are more uniform in size throughout the different regions of lung attenuation. The distinction of small airways disease from primary vascular disease requires the use of paired inspiratory/expiratory CT scans. The terms “mosaic perfusion” or “mosaic oligemia” have also been used to describe this heterogeneous pattern of lung attenuation. We believe that the term “mosaic pattern of lung attenuation” is preferable when describing areas of variable lung attenuation because the term “mosaic perfusion” implies pulmonary vascular pathology.

ACR CT Accreditation Program and the Lung Cancer Screening Program Designation

The ACR recognizes that low-dose CT for lung cancer screening has the potential to significantly reduce mortality from lung cancer in the appropriate high-risk population. The ACR supports the recommendations of the US Preventive Services Task Force and the National Comprehensive Cancer Network for screening patients. To be effective, lung cancer screening should be performed at sites providing high-quality low-dose CT examinations overseen and interpreted by qualified physicians using a structured reporting and management system. The ACR has developed a set of tools necessary for radiologists to take the lead on the front lines of lung cancer screening. The ACR Lung Cancer Screening Center designation is built upon the ACR CT accreditation program and requires use of Lung-RADS or a similar structured reporting and management system. This designation provides patients and referring providers with the assurance that they will receive high-quality screening with appropriate follow-up care.

Airways obstruction in patients with sarcoidosis: expiratory CT scan findings.

In patients with pulmonary sarcoidosis, air trapping as evidenced by expiratory high-resolution computed tomography (HRCT) is not specific for a given stage of disease. Air trapping can occur at the level of the secondary lobule, as well as in distributions suggesting sublobular, subsegmental, and segmental involvement. While air trapping can be a nonspecific finding, it is a common feature in patients with pulmonary sarcoidosis and is a supportive diagnostic finding.

Diffuse pulmonary ossification.

Diffuse pulmonary ossification (DPO) is an uncommon condition that is characterized by metaplastic bone formation in the lung parenchyma. It is usually not diagnosed clinically and may be apparent radiographically only when extensive. However, it is occasionally encountered at autopsy or on pathologic evaluation of surgical specimens. This article will review the clinical, histologic, and radiographic manifestations of DPO, focusing primarily on the chest radiograph and CT findings, both of which may be underappreciated, for even experienced radiologists may confuse DPO with other entities such as metastatic calcification as seen in chronic renal failure or chronic granulomatous disease.

Esophageal-pericardial fistula with purulent pericarditis secondary to esophageal carcinoma presenting with tamponade

A case of esophago-pericardial fistula secondary to esophageal carcinoma causing pericardial effusion and tamponade is presented. Palliation can be achieved effectively by limited thoracotomy, pericardial resection and drainage, and in selected cases esophageal stenting.

Chronic pulmonary thromboembolism. Air trapping on computed tomography and correlation with pulmonary function tests.

Objective We evaluated lung attenuation on inspiratory/expiratory computed tomography (CT) and spiral CT angiography (CTA) from patients with chronic pulmonary embolism and correlated the CT findings with pulmonary function test (PFT) results. Methods We retrospectively reviewed 9 patients with chronic embolism (mean age, 62.3 years; 5 women and 4 men). Paired inspiratory, expiratory CT and matching CTA images were reviewed, and lung attenuation was evaluated in each segment. Lower attenuation on inspiratory images and air trapping on expiratory images were subjectively assessed and correlated with PFT results. The relationship between the presence of clot and lung attenuation was evaluated. Nine age-matched normal subjects served as controls. Results Lower attenuation with mosaic perfusion and air trapping were identified in 6 and 9 patients, respectively (mean scores, 8.1 and 11.3, respectively). Air trapping was identified in 19 (42.2%) of 45 segments with lower attenuation on inspiratory images, but was also noted in 31 segments with normal inspiratory attenuation. Air trapping was associated with the presence of proximal arterial stenosis (P < 0.01), and the area showed less contrast enhancement than the adjacent lung (P < 0.05). Extent of air trapping correlated inversely with PFT parameters of peripheral airway obstruction such as maximum mid-expiratory flow rate (r = −0.86, P = 0.003). On the other hand, extent of mosaic perfusion did not correlate with PFT. Conclusions Air trapping is commonly seen in chronic embolism and is found in areas of relative hypoperfusion. The extent of air trapping correlates with parameters of peripheral airway obstruction.

Diaphragmatic hernias: a spectrum of radiographic appearances.

Diaphragmatic hernias are common, and although frequently incidental, recognition of both benign and life-threatening manifestations of diaphragmatic hernias is necessary to guide appropriate management. Congenital fetal diaphragmatic hernias, traumatic diaphragmatic rupture, and large symptomatic Bochdalek, Morgagni, and hiatal hernias are typically repaired surgically, while eventration, diaphragmatic slips, and small diaphragmatic hernias do not require intervention or imaging follow-up but should be recognized to avoid confusion with other diagnoses that require additional attention. This pictorial essay will explore the imaging findings and clinical characteristics of these entities.

High-resolution CT of peripheral airways diseases

Bronchiolitis and bronchiolectasis are nonspecific inflammatory processes of the small airways that have a variable, but often characteristic, appearance on HRCT. Familiarity with the imaging features of these disorders is crucial in rendering an accurate radiographic diagnosis.

Extrapleural hematomas: imaging appearance, classification, and clinical significance.

Purpose We sought to identify radiologic and clinical findings associated with extrapleural hematomas (EPHs), to formulate an imaging-based classification system for EPHs, and to identify any radiologic or clinical factors associated with surgical intervention. Materials and Methods Thirteen cases of EPH were gathered during the clinical review. An EPH was diagnosed on computed tomography (CT) if there was inward displacement of extrapleural fat by an intrathoracic peripheral fluid collection. The location and shape of each EPH were documented. For each case, the chest radiograph obtained in closest proximity to the CT acquisitions was also reviewed. The following additional data were also gathered: coexistent thoracic and nonthoracic injuries; mechanism of injury; treatment; and outcome. Results In our series, 92% of the patients (12/13) were male. The average age of the affected patients was 61 years. Most cases were related to blunt trauma (85%, 11/13). All these patients had additional injuries; rib fractures were most consistently present (81%, 9/11). All cases could be further categorized based on the appearance of their CT scan as biconvex or nonconvex. Biconvex EPHs tended to be larger than other types (average size of 4211 mL) and required surgical intervention in 80% of patients (4/5). No specific treatment was necessary in patients with nonconvex EPHs. Conclusions EPHs occur most commonly in high-energy blunt trauma; concomitant injuries are the rule, especially rib fractures. Biconvex hematomas tend to be large, likely resulting from high-pressure bleeding. Consequently, biconvex EPHs more often require surgical intervention. Nonconvex hematomas can usually be managed conservatively.

Thoracic Diseases Associated with HIV Infection in the Era of Antiretroviral Therapy: Clinical and Imaging Findings

The human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) pandemic has entered its 4th decade. Since the introduction of combination antiretroviral therapy (ART) in 1996, the number of AIDS-related deaths has plateaued worldwide. Today, owing to the effectiveness of ART, the HIV-infected population is aging and HIV infection has become a chronic illness. Non-AIDS comorbidities are increasing, and the spectrum of HIV-related thoracic diseases is evolving. In developed countries, bacterial pneumonia has become more common than Pneumocystis pneumonia. Its imaging appearance depends on the responsible organism, most commonly Streptococcus pneumoniae. Mycobacterium tuberculosis continues to be a major threat. Its imaging patterns vary depending on CD4 count. Primary lung cancer and Hodgkin lymphoma are two important non-AIDS-defining malignancies that are increasingly encountered at chest imaging. Human herpesvirus 8, also known as Kaposi sarcoma-associated herpesvirus (KSHV), is strongly linked to HIV-related diseases, including Kaposi sarcoma, multicentric Castleman disease, KSHV inflammatory cytokine syndrome, and primary effusion lymphoma. Immune reconstitution inflammatory syndrome is a direct complication of ART whose manifestations vary with the underlying disease. Given the high rate of smoking among HIV-infected patients, chronic obstructive pulmonary disease is another important cause of morbidity and mortality. A high degree of suspicion is required for the early diagnosis of pulmonary arterial hypertension and lymphocytic interstitial pneumonia, given their nonspecific manifestations. Finally, multilocular thymic cyst manifests as a cystic anterior mediastinal mass. Recognition of the clinical and radiologic manifestations of these less traditional HIV-related diseases can expedite diagnosis and treatment in the ART era.