Head to Head Comparison Between Perfusion and Function During Accelerated High-Dose Dipyridamole Magnetic Resonance Stress for the Detection of Coronary Artery Disease

The aim of this study was to compare the diagnostic accuracy of perfusion and wall motion (WM) during dipyridamole magnetic resonance in patients with chest pain syndrome. Ninety-three patients with normal baseline left ventricular function were referred for coronary angiography. Additional dipyridamole stress magnetic resonance testing (0.84 mg/kg over 6 minutes; using a Signa Cvi scanner) was performed. Cardiac-gated fast gradient-echo train sequences with a first pass of gadolinium contrast medium were used to assess myocardial perfusion. A perfusion reserve index was calculated as the ratio of dipyridamole to rest upslope. A perfusion reserve index value <1.54 in 2 contiguous myocardial segments was the perfusion positivity criterion. The WM positivity criterion was a segmental score increase of ≥1 grade in ≥2 segments. WM and the perfusion reserve index showed similar diagnostic accuracy for >50% quantitatively assessed coronary diameter reduction (86% for both), with WM having higher specificity (96% vs 66%, p <0.01) and lower sensitivity (82% vs 93%, p <0.05) than the perfusion reserve index. Perfusion had the highest accuracy values for coronary stenoses <75% (cutoff 59%) and WM for coronary stenoses ≥75% (cutoff 84%) (p <0.001). In conclusion, during dipyridamole magnetic resonance stress testing, perfusion and WM abnormalities have similar diagnostic accuracy, with perfusion showing higher sensitivity, particularly in the detection of moderate stenoses, and WM showing higher specificity. © 2008 Elsevier Inc. All rights reserved

Early hypertension is associated with reduced regional cardiac function, insulin resistance, epicardial, and visceral fat RID A-6953-2008

Mild-to-moderate hypertension is often associated with insulin resistance and visceral adiposity. Whether these metabolic abnormalities have an independent impact on regional cardiac function is not known. The goal of this study was to investigate the effects of increased blood pressure, insulin resistance, and ectopic fat accumulation on the changes in peak systolic circumferential strain. Thirty-five male subjects ( age: 47 +/- 1 years; body mass index: 28.4 +/- 0.6 kg. m(-2); mean +/- SEM) included 13 with normal blood pressure ( BP: 113 +/- 5/ 67 +/- 2 mm Hg), 13 with prehypertension ( BP: 130 +/- 1/ 76 +/- 2 mm Hg), and 9 newly diagnosed with essential hypertension ( BP: 150 +/- 2/ 94 +/- 2 mm Hg) who underwent cardiac magnetic resonance tissue tagging ( MRI) and MRI quantitation of abdominal visceral and epicardial fat. Glucose tolerance, on oral glucose tolerance test, and insulin resistance were assessed along with the serum lipid profile. All of the subjects had normal glucose tolerance, left- and right-ventricular volumes, and ejection fraction. Across the BP groups, left ventricular mass tended to increase, and circumferential shortening was progressively reduced at basal, midheart, and apical segments ( on average, from -17.0 +/- 0.5% in normal blood pressure to -15.2 +/- 0.7% in prehypertension to -13.6 +/- 0.8% in those newly diagnosed with essential hypertension; P = 0.004). Reduced circumferential strain was significantly associated with raised BP independent of age ( r = 0.41; P = 0.01) and with epicardial and visceral fat, serum triglycerides, and insulin resistance independent of age and BP. In conclusion, regional left ventricular function is already reduced at the early stages of hypertension despite the normal global cardiac function. Insulin resistance, dyslipidemia, and ectopic fat accumulation are associated with reduced regional systolic function

Standardized T2* Map of Normal Human Heart in Vivo To Correct T2* Segmental Artifacts

A segmental, multislice, multi-echo T2* MRI approach could be useful in heart iron-overloaded patients to account for heterogeneous iron distribution, demonstrated by histological studies. However, segmental T2* assessment in heart can be affected by the presence of geometrical and susceptibility artefacts, which can act on different segments in different ways. The aim of this study was to assess T2* value distribution in the left ventricle and to develop a correction procedure to compensate for artefactual variations in segmental analysis. MRI was performed in four groups of 22 subjects each: healthy subjects (I), controls (II) (thalassemia intermedia patients without iron overload), thalassemia major patients with mild (III) and heavy (IV) iron overload. Three short-axis views (basal, median, and apical) of the left ventricle were obtained and analyzed using custom-written, previously validated software. The myocardium was automatically segmented into a 16-segment standardized heart model, and the mean T2* value for each segment was calculated. Punctual distribution of T2* over the myocardium was assessed, and T2* inhomogeneity maps for the three slices were obtained. In group I, no significant variation in the mean T2* among slices was found. T2* showed a characteristic circumferential variation in all three slices. The effect of susceptibility differences induced by cardiac veins was evident, together with low-scale variations induced by geometrical artefacts. Using the mean segmental deviations as correction factors, an artefact correction map was developed and used to normalize segmental data. The correction procedure was validated on group II. Group IV showed no significant presence of segmental artefacts, confirming the hypothesis that susceptibility artefacts are additive in nature and become negligible for high levels of iron overload. Group III showed a greater variability with respect to normal subjects. The correction map failed to compensate for these variations if both additive and percentage-based corrections were applied. This may reinforce the hypothesis that true inhomogeneity in iron deposition exists