Should perfusion scintigraphy be done to follow patients with acute PE? If so, when?

Aims: This investigation evaluated the changes of pulmonary perfusion at four different points of follow-up within 1 year in patients with pulmonary embolism (PE) and the factors predictive of complete or incomplete recovery of pulmonary perfusion. Materials and Methods: Patients with symptomatic PE underwent perfusion lung scintigraphy (PLS) and blood gas analysis within 48 hours from clinical presentation, after 1 week, and after 1, 6 and 12 months; echocardiogram was made at baseline and after 6 and 12 months. All PLS were examined by two expert nuclear medicine physicians with a scoring method that attributed a score of 0, 0.5 or 1 for extension (maximum 18) to the presence of perfusion defects (PD), both at baseline and on each follow-up scan. Results: Among 183 patients who completed 1-year-follow-up, median baseline PD score was 8.2; it decreased significantly at each follow-up time point until 6 months (p<0.001). Median baseline alveolar-arterial difference of oxygen partial pressure (PA-aO2) was 50.9 and decreased significantly up to 1 month (p<0.001); median pulmonary artery systolic pressure (PAsP) was 45.9 mmHg, then decreased significantly until 12 months (p<0.001). A correlation was found between PD and both PA-aO2 (p<0.05) and PAsP (p<0.05). We found a correlation between PD ≠ 0 and PAsP≥ 40 mmHg at 12 months (p<0.05); in 6 (3.3%) of these patients such correlation was still present after 24 months, suggesting they could develop chronic thromboembolic pulmonary hypertension. Low baseline PD (odds ratio, OR,0.80, p< 0.0001) and high 1-week-percent recovery (OR 1.04, p< 0.0001) were predictive factors of complete 6 months-recovery. Conclusions: Perfusion scintigraphy may be useful to follow patients with PE. The follow-up should consist of three steps: the baseline examination since it reflects the severity of PE; the scan at 1-week that indicates the early amount of reperfusion; and the scan at 6-months that demonstrates the maximum attainable recovery. Patients with incomplete recovery and persistence of pulmonary hypertension on the 24-month control should be further studied for possible development of chronic thromboembolic pulmonary hypertension. Running title: Usefulness of follow-up in pulmonary embolism

Contemporary national trends and disparities for head CT use in emergency department settings: Insights from National Hospital Ambulatory Medical Care Survey (NHAMCS) 2007-2017.

BACKGROUND: The exponential growth in CT utilization in emergency department (ED) until 2008 raised concerns regarding cost and radiation exposure. Head CT was one of the commonest studies. This led to mitigating efforts such as appropriate use guidelines, policy and payment reforms. The impact of these efforts is not fully understood. In addition, disparities in outcomes of acute conditions presenting to the ED is well known however recent trends in imaging utilization patterns and disparities are not well understood. In this study, we describe nationwide trends and disparities associated with head CT in ED settings between 2007 and 2014. METHODS: We analyzed 2007-2017 National Hospital Ambulatory Medical Care Survey (NHAMCS) with the primary goal to assess the rate and patterns of head CT imaging in ED. RESULTS: There were an estimated 117 million in 2007 and 139 million ED visits in 2017. There was a 4% increase in the any CT use in 2017 compared to 2007. No significant change in head CT utilization rate was seen. The 2007 head CT rate was 6.7% (95% CI: 6.1-7.3) compared to 7.7% (95% CI: 6.8-8.6) in 2017. Trauma, Headache and Dizziness are the top three indications for head CT use in the ED respectively. On adjusted analyses, significantly higher head CT utilization was seen in elderly, (age\u3e65 yrs) and significantly lower utilization rate was seen in Non-Hispanic Black and Medicaid patients, and patients in rural locations. CONCLUSIONS: Previously reported exponential growth of CT use in ED is no longer seen. In particular, there was no significant change in ED head CT use between 2007 and 2017. Headache and Dizziness remain commonly used indications despite limited utility in most clinical scenarios, indicating continued need for appropriate use of imaging. There is significantly lower CT utilization in Non-Hispanic Black, Medicaid patients and those in rural locations, suggesting disparities in diagnostic work-up in marginalized and rural populations. This underscores the need for standardizing care regardless of race, insurance status and location

Proton-decoupled phosphorus-31 magnetic resonance spectroscopy in the evaluation of native and well-functioning transplanted kidneys

Rationale and objectives: To evaluate whether decoupling improves signal-to-noise ratio and frequency resolution of in vivo kidney spectra, and to compare native and well-functioning transplant kidneys. Methods: Proton decoupling in conjunction with three-dimensional chemical shift imaging (3D-CSI) in phosphorus-31 magnetic resonance (MR) spectroscopy was used with a spatial resolution of 64 cm3 and 17-minute acquisition time to compare native (n = 10) and well-functioning transplant (n = 9) kidneys. Results: Proton decoupling improved peak amplitudes by almost 30%, as well as chemical shift resolution of in vivo kidney spectra. No statistically significant differences in phosphometabolite ratios and renal spectra were observed between healthy volunteers and patients with nonrejecting transplants. The phosphodiester-phosphomonoester ratio was 3.02 +/- 0.88, phosphomonoester-inorganic phosphate ratio was 1.07 +/- 0.44, and inorganic phosphate-adenosine triphosphate ratio was 0.58 +/- 0.22 after correction for saturation effects. Conclusion: Improved spectra of native and transplant kidneys can be obtained in vivo with MR spectroscopy by using a short acquisition time.</p

MRI quantitative myocardial perfusion with compartmental analysis: a rest and stress study

K1 (first-order transfer constant from arterial plasma to myocardium for Gd-DTPA) and Vd (distribution volume of Gd-DTPA in myocardium) were measured in vivo in a canine model (n = 5) using MRI-derived myocardial perfusion curves and a compartmental model. Perfusion curves were obtained after a bolus injection of Gd-DTPA (0.04 mM/kg) with an inversion-prepared fast gradient echo sequence. Myocardium and blood signal intensity were converted to a concentration of Gd-DTPA, according to a model appropriate for short (&lt;1 s) interimage intervals characteristic of cardiac-triggered acquisitions. Before dipyridamole-induced stress, K1 and Vd, obtained from the fit of the MRI-derived perfusion curves, were 6.2 ± 1.4 (mHz) and 17.5 ± 4.2%, respectively. After dipyridamole infusion, a K1 increase of a factor of 2.82 ± 0.72 was measured (P = 0.003). No change was observed in Vd (P = 0.98). These results suggest that the K1 increase after dipyridamole reflects a flow-related effect that can be useful to quantity the MRI-derived perfusion curves