Samuel K. Dawn

Helical CT pulmonary angiography predictors of in-hospital morbidity and mortality in patients with acute pulmonary embolism.

Purpose To determine if CT variables predict in-hospital morbidity and mortality in patients with pulmonary embolism (PE). Materials and Methods CT scans and charts of 173 patients with CT scans positive for PE were reviewed. CT scans were reviewed for leftward ventricular septal bowing, increased right ventricle (RV) to left ventricle (LV) diameter ratio, clot burden, increased pulmonary artery to aorta diameter ratio, and oligemia. Charts were reviewed for severe morbidity and mortality outcomes: death from pulmonary emboli or any cause, and cardiac arrest. Charts were also reviewed for milder morbidity outcomes: intubation, vasopressor use, or admission to an intensive care unit (ICU) and for multiple comorbidities. Results No CT predictor was significantly associated with severe morbidity or mortality outcomes. Ventricular septal bowing and increased RV/LV diameter ratio were both associated with subsequent admission to an ICU (P = 0.004 and P = 0.025, respectively). Oligemia (either lung) was associated with subsequent intubation; right lung oligemia was associated with the subsequent use of vasopressors. After controlling for history of congestive heart failure, ischemic heart disease, and pulmonary disease, both septal bowing and an increased RV/LV diameter ratio remained associated with admission to an ICU. Conclusion No CT variables predicted severe in-hospital morbidity and mortality (death from pulmonary embolism, death from any cause, or cardiac arrest) in patients with PE. However, ventricular septal bowing and increased RV/LV diameter ratio were both strongly predictive of less severe morbidity, namely, subsequent ICU admission, and oligemia was associated with subsequent intubation and vasopressor use.

The radiologic spectrum of pulmonary Aspergillus infections.

Aspergillus infections may be categorized by specific radiographic patterns, the patients immunologic status, and the presence or absence of preexisting structural lung disease. General patterns include invasive aspergillosis (both vascular and airway invasive varieties and acute tracheobronchitis), semiinvasive aspergillosis (including allergic bronchopulmonary aspergillosis and hypersensitivity pneumonitis), mycetoma, allergic aspergillosis, and obstructing bronchial aspergillosis. Knowledge of these various radiographic patterns as well as the immune derangements that accompany these infections may allow proper diagnosis.

The silicone syndrome

Silicone syndrome results from migration of free liquid silicone into the pulmonary capillaries following subcutaneous injection. Such injections are often performed illegally by nonmedical personnel for cosmetic reasons, such as breast and gluteal augmentation. Once the free silicone reaches the pulmonary circulation, it induces interstitial inflammation, increased capillary permeability, alveolar edema, and alveolar hemorrhage, and produces a syndrome that clinically resembles fat embolization syndrome. Patients with silicone syndrome usually present with cough, fever, dyspnea, and chest pain, although a minority of patients primarily present with severe neurologic symptoms; mortality is usually high for this latter subset of patients. Thoracic imaging studies in patients with silicone syndrome usually show bilateral patchy areas of consolidation and ground-glass opacity, which is characteristically and often strikingly subpleural. These radiographic findings are suggestive of silicone syndrome in the proper clinical context.

Hypoxemia in a patient with end-stage liver disease

A number of pulmonary conditions producing hypoxemia may affect patients with chronic liver disease. Among these conditions, hepatopulmonary syndrome (HPS) is common, with the estimated prevalence of HPS among patients with end-stage liver disease ranging from 4% to 29%. HPS is considered present when the triad of liver dysfunction and/or portal hypertension, intrapulmonary vascular dilatation, and abnormal arterial oxygenation are noted in the absence of intrinsic cardiopulmonary disease. The pathogenesis of HPS is still unclear but is likely related to the effects of nitrous oxide and other vasoactive substances on the pulmonary vascular endothelium. HPS primarily affects the precapillary arterioles and capillaries in the lung bases, producing dilation of these vessels. These dilated vessels may produce hypoxemia through a combination of several mechanisms, including true anatomic shunts, ventilation-perfusion mismatch, and diffusion-perfusion defects. Chest radiographic imaging findings of HPS may be subtle and primarily consist of basilar reticular and nodular opacities. Thoracic CT often shows dilated peripheral pulmonary arteries with normal central pulmonary arteries. Pulmonary angiography may show dilated peripheral pulmonary arteries and early venous filling. 99mTechnetium-labeled macroaggregated albumin scans may show systemic embolization of radioactive tracer. Treatment of HPS consists of supplemental oxygen and, in severe cases, orthotopic liver transplantation.

An unusual cause of a pulmonary mass

Pulmonary artery aneurysms are rare thoracic vascular lesions. They may result from a variety causes, including congenital cardiovascular disease, infections, noninfectious inflammatory diseases, trauma and metabolic and idiopathic etiologies. The clinical presentation of pulmonary artery aneurysms is frequently nonspecific and is often dominated by underlying disease. Pulmonary artery aneurysms often present as solitary nodules or masses on chest radiography, and therefore a large differential diagnosis is often required. One circumstance in which pulmonary artery aneurysm should be specifically sought is the intensive care unit patient that develops a nodule near the pulmonary hilum at the site where a pulmonary arterial catheter tip was located. Cross-sectional imaging, particularly thoracic computed tomography, often allows a specific diagnosis of pulmonary artery aneurysm. Pulmonary artery aneurysms may be treated surgically, although catheter-based therapy with coils or detachable balloons is now usually the treatment of choice.

Cardiovascular abnormalities incidentally detected on helical CT pulmonary angiography: Spectrum of findings

Helical CT pulmonary angiography (HCTPA) is being increasingly used for the investigation of suspected pulmonary embolism. Because HCTPA involves the use of thin collimation and high contrast injection rates and volumetric acquisitions, it is ideally suited for evaluating the thoracic vascular system and may reveal numerous cardiovascular abnormalities unrelated to venous thromboembolism. Such abnormalities include systemic venous anomalies, atrial and ventricular masses, structural and congenital lesions of the pulmonary arteries, structural abnormalities of the interatrial septum, aortic and pericardial abnormalities, and abnormalities of surgical conduits and bypass grafts. Awareness of the imaging appearance of the various cardiovascular abnormalities that may be incidentally encountered with HCTPA will facilitate accurate diagnosis and may provide additional useful information in patients with negative studies.