High-resolution intravascular magnetic resonance quantification of atherosclerotic plaque at 3T

<p>Abstract</p> <p>Background</p> <p>The thickness of fibrous caps (FCT) of atherosclerotic lesions is a critical factor affecting plaque vulnerability to rupture. This study tests whether 3 Tesla high-resolution intravascular cardiovascular magnetic resonance (CMR) employing tiny loopless detectors can identify lesions and accurately measure FCT in human arterial specimens, and whether such an approach is feasible <it>in vivo </it>using animal models.</p> <p>Methods</p> <p>Receive-only 2.2 mm and 0.8 mm diameter intravascular loopless CMR detectors were fabricated for a clinical 3 Tesla MR scanner, and the absolute signal-to-noise ratio determined. The detectors were applied in a two-step protocol comprised of CMR angiography to identify atherosclerotic lesions, followed by high-resolution CMR to characterize FCT, lesion size, and/or vessel wall thickness. The protocol was applied in fresh human iliac and carotid artery specimens in a human-equivalent saline bath. Mean FCT measured by 80 μm intravascular CMR was compared with histology of the same sections. <it>In vivo </it>studies compared aortic wall thickness and plaque size in healthy and hyperlipidemic rabbit models, with post-mortem histology.</p> <p>Results</p> <p>Histology confirmed plaques in human specimens, with calcifications appearing as signal voids. Mean FCT agreed with histological measurements within 13% on average (correlation coefficient, <it>R </it>= 0.98; Bland-Altman analysis, -1.3 ± 68.9 μm). <it>In vivo </it>aortic wall and plaque size measured by 80 μm intravascular CMR agreed with histology.</p> <p>Conclusion</p> <p>Intravascular 3T CMR with loopless detectors can both locate atherosclerotic lesions, and accurately measure FCT at high-resolution in a strategy that appears feasible <it>in vivo</it>. The approach shows promise for quantifying vulnerable plaque for evaluating experimental therapies.</p

Dual use of Medicare and the Veterans Health Administration: are there adverse health outcomes?

BACKGROUND: Millions of veterans are eligible to use the Veterans Health Administration (VHA) and Medicare because of their military service and age. This article examines whether an indirect measure of dual use based on inpatient services is associated with increased mortality risk. METHODS: Data on 1,566 self-responding men (weighted N = 1,522) from the Survey of Assets and Health Dynamics among the Oldest Old (AHEAD) were linked to Medicare claims and the National Death Index. Dual use was indirectly indicated when the self-reported number of hospital episodes in the 12 months prior to baseline was greater than that observed in the Medicare claims. The independent association of dual use with mortality was estimated using proportional hazards regression. RESULTS: 96 (11%) of the veterans were classified as dual users. 766 men (50.3%) had died by December 31, 2002, including 64.9% of the dual users and 49.3% of all others, for an attributable mortality risk of 15.6% (p < .003). Adjusting for demographics, socioeconomics, comorbidity, hospitalization status, and selection bias at baseline, as well as subsequent hospitalization for ambulatory care sensitive conditions, the independent effect of dual use was a 56.1% increased relative risk of mortality (AHR = 1.561; p = .009). CONCLUSION: An indirect measure of veterans' dual use of the VHA and Medicare systems, based on inpatient services, was associated with an increased risk of death. Further examination of dual use, especially in the outpatient setting, is needed, because dual inpatient and dual outpatient use may be different phenomena

Dual use of Medicare and the Veterans Health Administration: are there adverse health outcomes?

Abstract Background Millions of veterans are eligible to use the Veterans Health Administration (VHA) and Medicare because of their military service and age. This article examines whether an indirect measure of dual use based on inpatient services is associated with increased mortality risk. Methods Data on 1,566 self-responding men (weighted N = 1,522) from the Survey of Assets and Health Dynamics among the Oldest Old (AHEAD) were linked to Medicare claims and the National Death Index. Dual use was indirectly indicated when the self-reported number of hospital episodes in the 12 months prior to baseline was greater than that observed in the Medicare claims. The independent association of dual use with mortality was estimated using proportional hazards regression. Results 96 (11%) of the veterans were classified as dual users. 766 men (50.3%) had died by December 31, 2002, including 64.9% of the dual users and 49.3% of all others, for an attributable mortality risk of 15.6% (p Conclusion An indirect measure of veterans' dual use of the VHA and Medicare systems, based on inpatient services, was associated with an increased risk of death. Further examination of dual use, especially in the outpatient setting, is needed, because dual inpatient and dual outpatient use may be different phenomena.</p

Tracking Physicochemical Conditions of Evaporite Deposition by Stable Magnesium Isotopes: A Case Study of Late Permian Langbeinites

Magnesium isotopic compositions of evaporite deposits may record information concerning brine evolution during deposition. We report Mg isotopic values (delta Mg-26(DSM3)) measured from an evaporite deposit of langbeinite (K2Mg2(SO4)(3)) found in the Permian Salado Formation. We used these data to model Mg isotope fractionation between langbeinite and its parent brine. In addition, both measured and theoretical results are used to estimate precipitation temperature and interpret depositional environment. The Salado langbeinite delta Mg-26 values are relatively low and fall within a relatively narrow range (-4.12 +/- 0.03 parts per thousand to -3.81 +/- 0.07 parts per thousand). Equilibrium fractionation factors between langbeinite and aqueous Mg2+ solutions were calculated using quantum chemical density functional theory. All computations were performed at the B3LYP/6-31 + G(d,p) level. Solvation effects were addressed using a solvent model ("water-droplet'' approach) and mineral structures were investigated using volume variable cluster models (VVCM). The equilibrium Mg isotopic fractionation factors a between langbeinite and model brine solution we obtained are 1.0005, 1.0004, and 1.0003 (Delta Mg-26(langb-water)approximate to 10(3)ln alpha = 0.473 parts per thousand, 0.390 parts per thousand, and 0.322 parts per thousand) at 10 degrees C, 25 degrees C, and 40 degrees C, respectively. These relatively large equilibrium fractionation factors indicate significant Mg isotope fractionation between langbeinite and its parent brine during precipitation, as langbeinite preferentially incorporates the heavier Mg-26 and Mg-25 isotopes. Rayleigh distillation modeling of the Salado langbeinite's relatively light Mg isotopic composition requires delta Mg-26(DSM3) values of -4 parts per thousand for the parent brine. Models favor a precipitation temperature as high as 40 degrees C under equilibrium conditions. Potential disequilibrium precipitation conditions suggested by Mg isotopic data also imply rapid deposition in a hot, arid sedimentary environment prevailing in the southwestern U.S. during the Late Permian

The integration of IVUS and OCT

Ultrasound and optical coherence tomography (OCT) provide complementary capabilities-ultrasound has high penetration depth but low resolution; OCT has high resolution but low penetration depth. The integration of these two technologies enable superior imaging capabilities for intravascular applications.Jiawen Li, Teng Ma, Qifa Zhou and Zhongping Che

Functional Status Outperforms Comorbidities in Predicting Acute Care Readmissions in Medically Complex Patients

OBJECTIVE: To examine functional status versus medical comorbidities as predictors of acute care readmissions in medically complex patients. DESIGN: Retrospective database study. SETTING: U.S. inpatient rehabilitation facilities. PARTICIPANTS: Subjects included 120,957 patients in the Uniform Data System for Medical Rehabilitation admitted to inpatient rehabilitation facilities under the medically complex impairment group code between 2002 and 2011. INTERVENTIONS: A Basic Model based on gender and functional status was developed using logistic regression to predict the odds of 3-, 7-, and 30-day readmission from inpatient rehabilitation facilities to acute care hospitals. Functional status was measured by the FIM(®) motor score. The Basic Model was compared to six other predictive models—three Basic Plus Models that added a comorbidity measure to the Basic Model and three Gender-Comorbidity Models that included only gender and a comorbidity measure. The three comorbidity measures used were the Elixhauser index, Deyo-Charlson index, and Medicare comorbidity tier system. The c-statistic was the primary measure of model performance. MAIN OUTCOME MEASURES: We investigated 3-, 7-, and 30-day readmission to acute care hospitals from inpatient rehabilitation facilities. RESULTS: Basic Model c-statistics predicting 3-, 7-, and 30-day readmissions were 0.69, 0.64, and 0.65, respectively. The best-performing Basic Plus Model (Basic+Elixhauser) c-statistics were only 0.02 better than the Basic Model, and the best-performing Gender-Comorbidity Model (Gender+Elixhauser) c-statistics were more than 0.07 worse than the Basic Model. CONCLUSIONS: Readmission models based on functional status consistently outperform models based on medical comorbidities. There is opportunity to improve current national readmission risk models to more accurately predict readmissions by incorporating functional data. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11606-015-3350-2) contains supplementary material, which is available to authorized users