Assessment of myocardial injury after reperfused infarction by T1ρ cardiovascular magnetic resonance.

BACKGROUND: The evolution of T1ρ and of other endogenous contrast methods (T2, T1) in the first month after reperfused myocardial infarction (MI) is uncertain. We conducted a study of reperfused MI in pigs to serially monitor T1ρ, T2 and T1 relaxation, scar size and transmurality at 1 and 4 weeks post-MI. METHODS: Ten Yorkshire swine underwent 90 min of occlusion of the circumflex artery and reperfusion. T1ρ, T2 and native T1 maps and late gadolinium enhanced (LGE) cardiovascular magnetic resonance (CMR) data were collected at 1 week (n = 10) and 4 weeks (n = 5). Semi-automatic FWHM (full width half maximum) thresholding was used to assess scar size and transmurality and compared to histology. Relaxation times and contrast-to-noise ratio were compared in healthy and remote myocardium at 1 and 4 weeks. Linear regression and Bland-Altman was performed to compare infarct size and transmurality. RESULTS: Relaxation time differences between infarcted and remote myocardial tissue were ∆T1 (infarct-remote) = 421.3 ± 108.8 (1 week) and 480.0 ± 33.2 ms (4 week), ∆T1ρ = 68.1 ± 11.6 and 74.3 ± 14.2, and ∆T2 = 51.0 ± 10.1 and 59.2 ± 11.4 ms. Contrast-to-noise ratio was CNRT1 = 7.0 ± 3.5 (1 week) and 6.9 ± 2.4 (4 week), CNRT1ρ = 12.0 ± 6.2 and 12.3 ± 3.2, and CNRT2 = 8.0 ± 3.6 and 10.3 ± 5.8. Infarct size was not significantly different for T1ρ, T1 and T2 compared to LGE (p = 0.14) and significantly decreased from 1 to 4 weeks (p < 0.01). Individual infarct size changes were ∆T1ρ = -3.8%, ∆T1 = -3.5% and ∆LGE = -2.8% from 1 - 4 weeks, but there was no observed change in infarct size for T2 or histologically. CONCLUSIONS: T1ρ was highly correlated with alterations left ventricle (LV) pathology at 1 and 4 weeks post-MI and therefore it may be a useful method endogenous contrast imaging of infarction.

Is the OSA-18 predictive of obstructive sleep apnea: comparison to polysomnography.

OBJECTIVES/HYPOTHESIS: To examine the ability of the OSA-18 to predict Obstructive Sleep Apnea (OSA) in a racially diverse population when compared to overnight polysomnography (PSG). STUDY DESIGN: Cross-sectional retrospective. METHODS: Children 2 to 12 years of age diagnosed with OSA who were treated at a tertiary care institution between 2008 and 2013 and had complete PSG and OSA-18 data were included. We performed logistic regression with OSA as the dependent variable and the OSA-18 total symptom score (TSS), age, gender, race, asthma, and body mass index (BMI) as independent variables. RESULTS: Seventy-nine children (32 females) were included (mean age 5.2 ± 2.4 years). The positive predictive value (PPV) was greater than 90 for an obstructive apnea-hypopnea index (oAHI) ≥ 1. The PPV and specificity were higher for white than for nonwhite children; however, sensitivity and negative predictive value (NPV) of OSA-18 TSS were low for mild, moderate, and severe OSA regardless of race. Age, race, and BMI were not significantly associated with oAHI. CONCLUSIONS: This study, conducted in a racially diverse cohort, examined the ability of the OSA-18 to predict OSA when compared to PSG-the gold standard-and found that sensitivity and NPV were extremely low for both white and nonwhite children. This suggests that the OSA-18 is not sufficiently sensitive to detect OSA nor sufficiently specific to determine the absence of OSA. The OSA-18 should be used as a quality-of-life indicator and is not a reliable substitute for PSG. LEVEL OF EVIDENCE: 4.