Comparative assessment of image quality for coronary CT angiography with iobitridol and two contrast agents with higher iodine concentrations: iopromide and iomeprol. A multicentre randomized double-blind trial.

OBJECTIVES: To demonstrate non-inferiority of iobitridol 350 for coronary CT angiography (CTA) compared to higher iodine content contrast media regarding rate of patients evaluable for the presence of coronary artery stenoses. METHODS: In this multicentre trial, 452 patients were randomized to receive iobitridol 350, iopromide 370 or iomeprol 400 and underwent coronary CTA using CT systems with 64-detector rows or more. Two core lab readers assessed 18 coronary segments per patient regarding image quality (score 0 = non diagnostic to 4 = excellent quality), vascular attenuation, signal and contrast to noise ratio (SNR, CNR). Patients were considered evaluable if no segment had a score of 0. RESULTS: Per-patient, the rate of fully evaluable CT scans was 92.1, 95.4 and 94.6 % for iobitridol, iopromide and iomeprol, respectively. Non-inferiority of iobitridol over the best comparator was demonstrated with a 95 % CI of the difference of [-8.8 to 2.1], with a pre-specified non-inferiority margin of -10 %. Although average attenuation increased with higher iodine concentrations, average SNR and CNR did not differ between groups. CONCLUSIONS: With current CT technology, iobitridol 350 mg iodine/ml is not inferior to contrast media with higher iodine concentrations in terms of image quality for coronary stenosis assessment. KEY POINTS: • Iodine concentration is an important parameter for image quality in coronary CTA. • Contrast enhancement must be balanced against the amount of iodine injected. • Iobitridol 350 is non-inferior compared to CM with higher iodine concentrations. • Higher attenuation with higher iodine concentrations, but no SNR or CNR differences.

T2-weighted cardiac MR assessment of the myocardial area-at-risk and salvage area in acute reperfused myocardial infarction: comparison of state-of-the-art dark blood and bright blood T2-weighted sequences.

PURPOSE: To compare different state-of-the-art T2-weighted (T2w) imaging sequences combined with late gadolinium enhancement (LGE) for myocardial salvage area (MSA) assessment by cardiac magnetic resonance (CMR). T2w imaging has been used to assess the myocardial area at risk (AAR) in acute myocardial infarction (AMI) patients, but its clinical application is challenging due to technical and physical limitations. MATERIALS AND METHODS: Thirty patients with reperfused AMI underwent complete CMR imaging 2-5 days after hospital admission. Myocardial AAR and MSA were quantified on four different T2w sequences: (a) free-breathing T2-prepared single-shot balanced steady-state free precession (T2p_ssbSSFP); (b) breathhold T2-weighted acquisition for cardiac unified T2 edema (ACUTE); (c) breathhold T2w dark-blood inversion recovery turbo-spin echo (IR-TSE) (short-term inversion recovery: STIR); and (d) free-breathing high-resolution T2 dark-blood navigated BLADE. The diagnostic performance of each technique was also assessed. RESULTS: Quantitative analysis showed significant differences in myocardial AAR extent as quantified by the four T2w sequences (P < 0.05). There were also significant differences in sensitivity, specificity and overall diagnostic performance. CONCLUSION: Detection and quantification of AAR, and thus of MSA, by T2wCMR in reperfused AMI patients varied significantly between different T2w sequences in the same clinical setting.

4D time-resolved magnetic resonance angiography for noninvasive assessment of pulmonary arteriovenous malformations patency.

PURPOSE: To assess the capability of four-dimensional (4D) time-resolved magnetic resonance angiography (MRA) to assess pulmonary arteriovenous malformations (PAVMs) patency by analyzing pulmonary arterial and venous enhancement kinetics. MATERIALS AND METHODS: Seven patients with eight documented patent PAVMs underwent a 4D-MRA with keyhole and viewsharing compression at 3T with the following parameters: spatial resolution 0.87 × 0.87 × 1.4 mm(3); field of view 500 × 350 × 238 mm(3); dynamic scan time (temporal resolution) 1.2 seconds; total acquisition time 18.1 seconds for six dynamic datasets (6 × 1.2 sec + reference scan: 10.9 sec). All images were reviewed by two experienced radiologists. Image quality was rated on a qualitative 5-point scale (1: not assessable to 5: excellent). Signal value was measured on cross-sectional planes for the afferent arteries and efferent veins of the PAVM, and for normal reference healthy arteries and veins. The difference in time to peak for each coupled artery/vein (dTTPav) was calculated and compared with a Mann-Whitney test between PAVMs and reference vessels. RESULTS: Mean image quality was 3.2 ± 0.9. dTTPav was significantly smaller in PAVMs (0.15 ± 0.76 sec) than in reference vessels (3.75 ± 1.62 sec), P < 0.001. CONCLUSION: 4D-MRA is a promising tool for noninvasive assessment of PAVM patency.

Noninvasive assessment of the prevalence and characteristics of coronary atherosclerotic plaques by multidetector computed tomography in asymptomatic type 2 diabetic patients at high risk of significant coronary artery disease: a preliminary study.

BACKGROUND: There is a need to identify diabetic patients at risk of cardiovascular events before symptom onset. AIMS: To evaluate the prevalence and characteristics of coronary atherosclerotic plaques in asymptomatic type 2 diabetic patients with coronary risk factors but without known coronary artery disease, using multidetector computed tomography. METHODS: High-resolution 40-slice coronary computed tomography was performed prospectively in 42 consecutive type 2 diabetic patients (mean age 62 years; range 50-77 years; 28 men) with over one or more carotid atherosclerotic plaque and no coronary artery disease symptoms. Computed tomography data were evaluated for calcium score and the presence of coronary plaques. Plaque type, distribution, extensive character and obstructive nature were determined per patient for each segment. RESULTS: No plaques were detected in 11 (26.2%) patients. Atherosclerotic plaques were detected in 31 (73.8%) patients. A total of 147 coronary segments with plaque were identified, of which 11 (7.5%) contained hypodense plaques, 28 (19%) mixed plaques and 108 (73.5%) calcified plaques. Hypodense plaques were noted in 4/15 (26.7%) patients without coronary calcifications. Most calcified and hypodense plaques resulted in lumen narrowing of less than 50%; most mixed plaques resulted in lumen narrowing greater than 50%. Obstructive disease was detected in 9/11 patients with a high calcium score (>400). CONCLUSION: This preliminary study demonstrates that a high proportion of asymptomatic type 2 diabetic patients present without coronary plaques detectable by multidetector computed tomography, despite concomitant carotid atherosclerotic lesions. Computed tomography seems to detect a high proportion of plaques compared with conventional angiography in these specific patients.

Multidetector computed tomography in reperfused acute myocardial infarction. Assessment of infarct size and no-reflow in comparison with cardiac magnetic resonance imaging.

OBJECTIVES: (1) To determine the accuracy of delayed enhancement multidetector computed tomography (MDCT) in measuring the extent of acute myocardial infarct and no-reflow areas using cardiac magnetic resonance imaging (MRI) as standard of reference and (2) to define the optimum timing between injection and MDCT image acquisition to characterize infarcted myocardium and no-reflow areas after reperfusion therapy. MATERIALS AND METHODS: Nineteen patients were prospectively included after acute myocardial infarction and revascularization. Each patient had an MDCT acquisition before and 5 and 10 minutes after injection of 1.5 mL/kg iodinated contrast medium, and a contrast-enhanced MRI at 5 and 10 minutes after injection of 0.2 mmol/kg gadolinium chelate. We assessed image quality and infarct extent using MDCT and MRI, and we measured parameters related to iodinated contrast media kinetics (DeltaHU and DeltaHU ratio). RESULTS: The areas of hyperenhanced myocardium located on the MDCT corresponded to the occluded vessel located on the coronary angiogram (kappa = 0.9). There were strong correlations between the extent of hyperenhanced infarcted myocardium on MDCT and MRI at 5 minutes (20.4% +/- 2.7% of left ventricle (LV) and 20.9% +/- 2.4%, respectively, R = 0.85; P < 0.0001) and 10 minutes after injection (21.0% +/- 2.9% of LV and 19.4% +/- 2.5%, respectively, R = 0.80; P < 0.0001). However, the correlation between the area of hypoenhanced myocardium measured using MDCT and CMR 5 minutes after injection (R = 0.86; P < 0.0001) was better than the measurement obtained 10 minutes after injection (R = 0.64; P = 0.002). On contrast-enhanced MDCT, 5 minutes after injection, the signal-to-noise ratio was significantly higher than at 10 minutes after injection in LV blood (28 +/- 1 to 21 +/- 1, respectively; P = 0.0007), normal myocardium (18 +/- 1 to 15 +/- 1; P = 0.0009), and hyperenhanced infarcted myocardium (24 +/- 1 to 20 +/- 1; P = 0.004). MDCT image quality was significantly better at 5 minutes (3.2 +/- 0.1) than at 10 minutes (2.8 +/- 0.2, P = 0.01, kappa = 0.4). The DeltaHU ratio increased slightly but significantly between 5 minutes (0.83 +/- 0.01) and 10 minutes (0.93 +/- 0.01; P = 0.01), suggesting a slow wash-in and wash-out of contrast medium in infarcted myocardium. CONCLUSION: In ST segment elevation myocardial infarction patients contrast-enhanced MDCT is an accurate method for characterizing and sizing myocardial infarct and no-reflow. Contrast-enhanced MDCT performed 5 minutes after injection yields a higher signal-to-noise ratio and image quality than the 10 minutes time point with no difference in the extent of infarct measurement.

Assessment of acute myocardial infarction using MDCT after percutaneous coronary intervention: comparison with MRI.

OBJECTIVE: Imaging to determine myocardial infarct size is difficult in the emergency setting because the current gold standards, MRI and nuclear medicine techniques, are difficult to perform in unstable patients. Delayed enhanced MDCT has recently been proposed as a technique to study contrast uptake in infarcted myocardium. In this study, we compared the extent of acute myocardial infarction as measured by delayed enhanced MDCT performed immediately after percutaneous coronary intervention (PCI) without an additional iodine injection with that measured by delayed gadolinium-enhanced MRI. SUBJECTS AND METHODS: Nineteen consecutive patients presenting with primary acute myocardial infarction underwent delayed enhanced MDCT immediately after coronary angioplasty and underwent delayed enhanced MRI within 8 days of angioplasty. Only patients with a thrombolysis in myocardial infarction (TIMI) score of 0 or 1 of the culprit coronary artery before endovascular angioplasty and TIMI score of 2 or 3 after angioplasty were selected. Comparison of delayed enhanced MDCT and delayed enhanced MRI was performed by three observers and focused on identifying the involved segments and determining the transmural extent of enhancement and infarct size. RESULTS: The mean signal intensity was significantly higher in the involved territory than in healthy myocardium: 197 +/- 81 H versus 71 +/- 20 H, respectively (p < 0.0001). We found significant agreement between delayed enhanced MDCT and delayed enhanced MRI for the number of involved segments, transmural extent of enhancement, and infarct size (r(2) = 0.74, 0.76, and 0.67, respectively; p < 0.0001) with good interobserver reproducibility (kappa = 0.8). CONCLUSION: The results of our study show that delayed enhanced MDCT allows accurate visualization of early myocardial contrast uptake compared with delayed enhanced MRI and does not require an additional contrast injection after PCI.

Dobutamine-tagged MRI for inotropic reserve assessment in severe CAD: relationship with PET findings.

The impact of blood flow reductions on the intramyocardial inotropic reserve has not yet been established in coronary artery disease (CAD). We therefore evaluated in severe CAD the relationship between positron emission tomography (PET) patterns of perfusion and glucose uptake and the corresponding tagged magnetic resonance imaging (tagged MRI) values of midmyocardial strains under low-dose dobutamine. Eighteen patients underwent tagged MRI (at rest, with dobutamine) and H2(15)O/18F-fluorodeoxyglucose PET. Regional midmyocardial circumferential shortening (Ecc) and PET patterns (normal, match viable, mismatch viable, and infarcted) were assessed in three tagged MRI/PET short-axis slices. Regional Ecc at rest correlated with both perfusion (r = 0.49) and glucose uptake (r = 0.58). The presence of the inotropic reserve was similar in normal, match viable, and infarcted (approximately 40% of regions vs. 52% in mismatch viable, P < 0.05), but the extent of the increase after dobutamine was lower in infarcted regions (P = 0.06). Within each PET pattern, regions were grouped according to their Ecc values at rest into three categories (high, intermediate, and low contractile performance). In mismatch viable (hibernation), the inotropic reserve was similar among the three categories, but in the other PET patterns the presence and extent of the inotropic reserve was higher in those regions with lowest Ecc (without significant differences in perfusion). In severe CAD, the presence of the inotropic reserve assessed by midmyocardial changes under dobutamine does not relate to resting perfusion. At a similar level of perfusion, the presence of the inotropic reserve is inversely related to contractile performance at rest, but our results suggest that it may not be true for hibernating myocardium.