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Biomedical subjects

Samuel K Dawn

Publications and source records attributed to Samuel K Dawn.

7 recordsLinked to original sources
PubMed2005

Imaging findings in Takayasu's arteritis.

OBJECTIVE: The objective of our study was to evaluate the clinical usefulness of cross-sectional imaging for establishing the diagnosis of Takayasu's arteritis (TA), an inflammatory vascular disorder that produces arterial stenoses and aneurysms primarily involving the thoracoabdominal aorta and its branches and the pulmonary arteries. CONCLUSION: CT and MRI findings of TA include vascular wall thickening and enhancement early in the disease, and arterial stenoses, occlusions, and aneurysms later in the disease. Cross-sectional imaging is useful for establishing the diagnosis of TA and for showing response to nonsurgical therapy or for planning a surgical intervention.

Adult↗
PubMed2003

Thoracic aorta imaging with multisclice CT.

Multislice CT aortography represents a major advance in the noninvasive evaluation of thoracic aortic disease. MSTCA is rapidly becoming the preferred modality for the initial investigation of acute aortic syndromes. Although scan quality is usually excellent, special attention to various technical parameters is required to optimize image quality. Familiarity with diagnostic pitfalls and the common imaging presentations of various thoracic aortic syndromes is necessary for accurate diagnosis.

Aorta, Thoracic↗
PubMed2003

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.

Acute Disease↗
PubMed2002

Thoracic complications of illicit drug use: an organ system approach.

Illicit drug use constitutes a major health problem and may be associated with various thoracic complications. These complications vary depending on the specific drug used and the route of administration. Commonly abused drugs that may play a role in causing thoracic disease include cocaine, opiates, and methamphetamine derivatives. Intravenously abused oral medications may contain filler agents that may be responsible for disease. Thoracic complications may be categorized as pulmonary, pleural, mediastinal, cardiovascular, and chest wall complications. Pulmonary complications of drug abuse include pneumonia, cardiogenic edema, acute lung injury, pulmonary hemorrhage, and aspiration pneumonia. Filler agents such as talc may result in panacinar emphysema or high-attenuation upper-lobe conglomerate masses. The primary pleural complication of illicit drug use is pneumothorax. Mediastinal and cardiovascular complications of illicit drug use include pneumomediastinum, cardiomyopathy, myocardial infarction, aortic dissection, and injection-related pseudoaneurysms. Chest wall complications include diskitis and vertebral osteomyelitis, epidural abscess, necrotizing fasciitis, costochondritis, and septic arthritis. Categorization of thoracic complications of illicit drug use may facilitate understanding of these disorders and allow accurate diagnosis.

Aortic Dissection↗
PubMed2002

Helical CT with sagittal and coronal reconstructions: accuracy for detection of diaphragmatic injury.

OBJECTIVE: The objectives of our study were to determine the accuracy of single-detector helical CT (including coronal and sagittal reconstructions) for the diagnosis of traumatic diaphragmatic injury, establish measurements for the thickness of the normal diaphragmatic crus, and describe an additional sign of diaphragmatic injury: active arterial extravasation of contrast material at the level of the diaphragm. MATERIALS AND METHODS: The CT scans of 25 patients with surgically proven diaphragmatic injury and 22 patients with surgically confirmed uninjured diaphragms were blindly reviewed by five thoracic radiologists. Sagittal and coronal reconstructions were performed for 20 of the 25 patients with a proven diaphragmatic injury and for all the patients without a diaphragmatic injury. Scans were evaluated for findings suggestive of diaphragmatic injury and for associated injuries. Reviewers scored the usefulness of the reconstructed images for establishing the final diagnosis. Measurements of the right and left crura were performed to establish a threshold measurement that would enable radiologists to discriminate between a normal diaphragm and an injured diaphragm. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of helical CT were 84%, 77%, 81%, 81%, and 83%, respectively. Scans showing active arterial extravasation of contrast material enabled reviewers to correctly identify diaphragmatic injury in two patients. Reconstructed images confirmed the correct diagnosis in three patients but supported an incorrect diagnosis in two. The mean thickness of the diaphragmatic crura (right and left) was not significantly greater in patients with an injured diaphragm than in those with an uninjured diaphragm. CONCLUSION: Helical CT shows good sensitivity, specificity, and accuracy for the diagnosis of diaphragmatic injury. Coronal and sagittal reconstructions are of limited use in establishing or refuting this diagnosis. Active arterial extravasation of contrast material near the diaphragm should raise suspicion for injury. Crus measurements cannot be used to reliably distinguish between injured and uninjured diaphragms.

Adolescent↗
PubMedDate not supplied

The radiologic spectrum of pulmonary Aspergillus infections.

Aspergillus infections may be categorized by specific radiographic patterns, the patient's 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.

Aspergillosis, Allergic Bronchopulmonary↗