Thoracic Ultrasound: Technique, Applications, and Interpretation.

Thoracic ultrasound is used at the bedside in emergency and critical care settings. Advantages of ultrasound include rapid real-time, low-cost, diagnostic information that can direct patient care without the use of ionizing radiation. We describe methods on how to perform lung ultrasound, with the intent to educate the radiologist who might otherwise be relatively unfamiliar with thoracic sonography. We describe and depict the normal sonographic appearance of lung anatomy. We also show the sonographic appearance of a wide range of lung and pleural pathologies such as pneumonia, pneumothorax, as well as lung and pleural masses. We review various lines and signs described in the literature, such as A-lines, B-lines, the stratosphere sign, and the bat-wing sign. Finally, we correlate our findings with chest x-ray and computerized tomography to emphasize the anatomy.

Biomechanical factors in coronary vulnerable plaque risk of rupture: intravascular ultrasound-based patient-specific fluid-structure interaction studies.

OBJECTIVES: The aim of this study was to elucidate the mechanisms and underlying biomechanical factors that may play a role in the risk of rupture of vulnerable plaques (VPs) by studying patient-based geometries of coronary arteries reconstructed from intravascular ultrasound (IVUS) imaging utilizing fluid-structure interaction (FSI) numerical simulations. BACKGROUND: According to recent estimates, coronary artery disease is responsible for one in six deaths in the USA, and causes about one million heart attacks each year. Among these, the rupture of coronary VPs followed by luminal blockage is widely recognized as a major cause of sudden heart attacks; most importantly, the patients may appear as asymptomatic under routine screening before the occurrence of the index event. MATERIALS AND METHODS: FSI simulations of patient-based geometries of coronary arteries reconstructed from IVUS imaging were performed to establish the dependence of the risk of rupture of coronary VP on biomechanical factors, such as the fibrous cap thickness, presence of microcalcification in the fibrous cap, arterial anisotropy, and hypertension. RESULTS: Parametric FSI simulations indicated that mechanical stresses (von Mises stresses) increase exponentially with the thinning of the fibrous cap as well as with increasing levels of hypertension. The inclusion of a microcalcification in the fibrous cap considerably increases the risk of rupture of VP , with an ∼two-fold stress increase in the VP stress burden. Furthermore, the stress-driven reorientation and biochemical degradation of the collagen fibers in the vessel wall because of atherosclerosis (studied with an anisotropic fibrous cap 65° fiber reorientation angle) results in a 30% increase in the stress levels as compared with simulations with isotropic material models, clearly indicating that the latter, which are commonly used in such studies, underestimate the risk of rupture of VP. CONCLUSION: The results indicate that IVUS-based patient-specific FSI simulations for mapping the wall stresses, followed by analysis of the biomechanical risk factors, may be used as an additional diagnostic tool for clinicians to estimate the plaque burden and determine the proper treatment and intervention.

Patient-based abdominal aortic aneurysm rupture risk prediction with fluid structure interaction modeling.

Elective repair of abdominal aortic aneurysm (AAA) is warranted when the risk of rupture exceeds that of surgery, and is mostly based on the AAA size as a crude rupture predictor. A methodology based on biomechanical considerations for a reliable patient-specific prediction of AAA risk of rupture is presented. Fluid-structure interaction (FSI) simulations conducted in models reconstructed from CT scans of patients who had contained ruptured AAA (rAAA) predicted the rupture location based on mapping of the stresses developing within the aneurysmal wall, additionally showing that a smaller rAAA presented a higher rupture risk. By providing refined means to estimate the risk of rupture, the methodology may have a major impact on diagnostics and treatment of AAA patients.