Background-In patients with coronary artery stents, no direct noninvasive coronary artery imaging is possible with magnetic resonance (MR). A well-established method for the assessment of the functional significance of a coronary lesion is the measurement of coronary flow reserve by invasive intracoronary Doppler. The purpose of the study was to determine coronary flow velocity reserve (CFVR) with MR after stent deployment. Methods and Results-Thirty-eight patients after successful PTCA and stent deployment were included. CFVR was measured perpendicular to the artery distal to the stent using phase-contrast velocity quantification at rest and during adenosine-stimulated hyperemia with a 1.5T MR tomograph (ACS NT, Philips). Measurements were repeated after 3 months and compared with invasive coronary angiography. In 18 patients, additional invasive Doppler flow measurements were obtained. CFVR could be determined in 29 of 38 (76%) of the patients. After 3 months, significant differences were obtained between coronary arteries with and without restenosis. Using a threshold of 1.2, a sensitivity of 83% with a specificity of 94% was achieved for Ն75% stenoses. CFVR with CMR was similar to Doppler results (rϭ0.87), with a mean relative difference of 7.5%. Conclusions-In patients with preserved coronary microcirculating vasoreactivity that are suitable for MR coronary angiography and flow assessments, CMR measures of coronary blood flow velocities reserve may be used to detect in-stent restenosis.
Purpose:To prospectively determine the feasibility and accuracy of strain-encoded (SENC) magnetic resonance imaging (MRI) for the characterization of the right ventricular free wall (RVFW) strain and timing of contraction at 3.0 Tesla (3T) MRI.
Materials and Methods:In 12 healthy volunteers the RVFW was divided into three segments (anterior, lateral, and inferior) in each of three short-axis (SA) slices (apical, mid, and basal) and into three segments (apical, mid, and basal) in a four-chamber view. The study was repeated on a different day and interobserver and interstudy agreements were evaluated.Results: Maximal systolic longitudinal strain values were highest at the apex and base, with a pronounced decrease in the medial segments (apex: -19.1% Ϯ 1.4; mid: -17.4% Ϯ 2; base: -19.4% Ϯ 2.4, P Ͻ 0.001), and maximal systolic circumferential strain showed the highest values at the apex (apex: -18.1% Ϯ 1.7; mid: -17.6% Ϯ 1.2; base: -16.6% Ϯ 0.9, P Ͻ 0.001). Peak systolic longitudinal and circumferential shortening occurred earliest at the apex compared to the mid-ventricle and base. Excellent interobserver and interstudy correlation and agreement were observed.
Conclusion:The use of SENC MRI for the assessment of normal RV contraction pattern is feasible and accurate in 3T MRI.
Purpose:To define the reproducibility of strain-encoded (SENC) magnetic resonance imaging (MRI) for assessment of regional left ventricular myocardial strain and timing of contraction in a 3T MRI system.
Materials and Methods:The study population consisted of 16 healthy subjects. SENC measurements were performed in three short-axis (SA) slices (apical, mid, and basal) and three long-axis (LA) views (two-, three-, and four-chamber) for assessment of maximal transmural systolic strain and time to peak strain. To assess the interobserver and interstudy reproducibility, analysis of SENC MRI was performed by two independent observers who were blinded to each other's results and four studies were repeated on a different day.Results: Maximal longitudinal strain was highest at the apex, as was maximal circumferential strain. Peak longitudinal strain occurred earliest at the base, as did peak circumferential strain. Interclass correlation coefficient between observers and repeated studies ranged from 0.92 to 0.98 (P Ͻ 0.001 for all).
Conclusion:The present study demonstrates the ability of SENC MRI to define regional left ventricular strain and the time sequence of regional strain. SENC MRI may represent a highly objective method for quantifying regional left ventricular function.
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