Photoacoustic effect for multiply scattered light

We consider the photoacoustic effect for multiply scattered light in a random medium. Within the accuracy of the diffusion approximation to the radiative transport equation, we present a general analysis of the sensitivity of a photoacoustic wave to the presence of one or more small absorbing objects. Applications to tumor detection by photoacoustic imaging are suggested

National trends in emergency room diagnosis of pulmonary embolism, 2001–2010: a cross-sectional study

Background: Little is known about the United States diagnosis and burden of pulmonary embolism (PE) in the emergency department (ED), and their evolution over the past decade. We examined nationally representative data to evaluate factors associated with and trends in ED diagnosis of PE. Methods: We conducted a cross-sectional study using National Hospital Ambulatory Medical Care Survey (NHAMCS) data from January 1, 2001 to December 31, 2010. We identified all ED patient visits where PE was diagnosed and corresponding demographic, hemodynamic, testing and disposition data. Analyses were performed using descriptive statistics and multivariable logistic regression. Results: During the study period 988,000 weighted patient visits with diagnosis of PE were identified. Among patients with an ED visit, the likelihood of having a diagnosis of PE per year increased significantly from 2001 to 2010 (odds ratio [OR] 1.091, 95% confidence interval [CI] 1.034-1.152, P = 0.002 for trend) when adjusted for demographic and hospital information. In contrast, when further adjusted for the use of computed tomography (CT) among patients in the ED, the likelihood of having a diagnosis of PE per year did not change (OR 1.041, 95% CI 0.987-1.097, P = 0.14). Overall, 75.1% of patients seen with a diagnosis of PE were hemodynamically stable; 86% were admitted with an in-hospital death rate under 3%. Conclusions: The proportion of ED visits with a diagnosis of PE increased significantly from 2001 to 2010 and this rise can be attributed in large part to the increased availability and use of CT. Most of these patients were admitted with low in-hospital mortality. Keywords: Pulmonary embolism Emergency department Computed Tomography (CT) pulmonary angiograph

CT pulmonary angiography: increasingly diagnosing less severe pulmonary emboli.

It is unknown whether the observed increase in computed tomography pulmonary angiography (CTPA) utilization has resulted in increased detection of pulmonary emboli (PEs) with a less severe disease spectrum.Trends in utilization, diagnostic yield, and disease severity were evaluated for 4,048 consecutive initial CTPAs performed in adult patients in the emergency department of a large urban academic medical center between 1/1/2004 and 10/31/2009. Transthoracic echocardiography (TTE) findings and peak serum troponin levels were evaluated to assess for the presence of PE-associated right ventricular (RV) abnormalities (dysfunction or dilatation) and myocardial injury, respectively. Statistical analyses were performed using multivariate logistic regression.268 CTPAs (6.6%) were positive for acute PE, and 3,780 (93.4%) demonstrated either no PE or chronic PE. There was a significant increase in the likelihood of undergoing CTPA per year during the study period (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.04-1.07, P<0.01). There was no significant change in the likelihood of having a CTPA diagnostic of an acute PE per year (OR 1.03, 95% CI 0.95-1.11, P = 0.49). The likelihood of diagnosing a less severe PE on CTPA with no associated RV abnormalities or myocardial injury increased per year during the study period (OR 1.39, 95% CI 1.10-1.75, P = 0.01).CTPA utilization has risen with no corresponding change in diagnostic yield, resulting in an increase in PE detection. There is a concurrent rise in the likelihood of diagnosing a less clinically severe spectrum of PEs

Annual CTPA utilization patterns.

<p>Graph shows an increase in the number of CTPAs ordered from 2004 to 2009 with concurrent increase in number of scans positive for an acute PE.</p

Association of various demographic variables and likelihood of a positive CTPA scan.

<p>Association of various demographic variables and likelihood of a positive CTPA scan.</p

Annualized CTPA utilization, diagnostic yield and disease severity data.

*<p>Incomplete year: includes data from Jan. 1, 2009 to Oct. 31, 2009.</p

Association of various demographic variables and likelihood of diagnosing a less severe disease spectrum.

<p>Association of various demographic variables and likelihood of diagnosing a less severe disease spectrum.</p

Annual number of PEs diagnosed by CTPA, number of PEs without associated RV abnormalities or myocardial injury, and number of PEs with associated RV dysfunction and/or dilatation and/or myocardial injury.

<p>Annual number of PEs diagnosed by CTPA, number of PEs without associated RV abnormalities or myocardial injury, and number of PEs with associated RV dysfunction and/or dilatation and/or myocardial injury.</p