This study clinically implemented a ready-to-use quantitative perfusion (QP) cardiovascular magnetic resonance (QP CMR) workflow, encompassing a simplified dual-bolus gadolinium-based contrast agent (GBCA) administration scheme and fully automated QP image post-processing. Twenty-five patients with suspected obstructive coronary artery disease (CAD) underwent both adenosine stress perfusion CMR and an invasive coronary angiography or coronary computed tomography angiography. The dual-bolus protocol consisted of a pre-bolus (0.0075 mmol/kg GBCA at 0.5 mmol/ml concentration + 20 ml saline) and a main bolus (0.075 mmol/kg GBCA at 0.5 mmol/ml concentration + 20 ml saline) at an infusion rate of 3 ml/s. The arterial input function curves showed excellent quality. Stress MBF ≤ 1.84 ml/g/min accurately detected obstructive CAD (area under the curve 0.79; 95% Confidence Interval: 0.66 to 0.89). Combined visual assessment of color pixel QP maps and conventional perfusion images yielded a diagnostic accuracy of 84%, sensitivity of 70% and specificity of 93%. The proposed easy-to-use dual-bolus QP CMR workflow provides good image quality and holds promise for high accuracy in diagnosis of obstructive CAD. Implementation of this approach has the potential to serve as an alternative to current methods thus increasing the accessibility to offer high-quality QP CMR imaging by a wide range of CMR laboratories.
Objectives To characterize the temporal alterations in native T1 and extracellular volume (ECV) of remote myocardium after acute myocardial infarction (AMI), and to explore their relation to left ventricular (LV) remodeling. Methods Forty-two patients with AMI successfully treated with primary PCI underwent cardiovascular magnetic resonance after 4–6 days and 3 months. Cine imaging, late gadolinium enhancement, and T1-mapping (MOLLI) was performed at 1.5T. T1 values were measured in the myocardial tissue opposite of the infarct area. Myocardial ECV was calculated from native- and post-contrast T1 values in 35 patients, using a correction for synthetic hematocrit. Results Native T1 of remote myocardium significantly decreased between baseline and follow-up (1002 ± 39 to 985 ± 30ms, p<0.01). High remote native T1 at baseline was independently associated with a high C-reactive protein level (standardized Beta 0.32, p = 0.04) and the presence of microvascular injury (standardized Beta 0.34, p = 0.03). ECV of remote myocardium significantly decreased over time in patients with no LV dilatation (29 ± 3.8 to 27 ± 2.3%, p<0.01). In patients with LV dilatation, remote ECV remained similar over time, and was significantly higher at follow-up compared to patients without LV dilatation (30 ± 2.0 versus 27 ± 2.3%, p = 0.03). Conclusions In reperfused first-time AMI patients, native T1 of remote myocardium decreased from baseline to follow-up. ECV of remote myocardium decreased over time in patients with no LV dilatation, but remained elevated at follow-up in those who developed LV dilatation. Findings from this study may add to an increased understanding of the pathophysiological mechanisms of cardiac remodeling after AMI.
Magnetic resonance phase difference techniques are commonly used to study flow velocities in the human body. Acceleration is often present, either in the form of pulsatile flow, or in the form of convective acceleration. Questions have arisen about the exact time point at which the velocity is encoded, and also about the sensitivity to (convective) acceleration and higher order motion derivatives. It has become common practice to interpret the net phase shifts measured with a phase difference velocity technique as being the velocity at a certain (Taylor) expansion time point, chosen somewhere between the RF excitation and the echo readout. However, phase shifts are developed over the duration of the encoding magnetic field gradient wave form, and should therefore be interpreted as a more or less time-averaged velocity. It will be shown that the phase shift as measured with a phase difference velocity technique represents the velocity at the "gravity" center of the encoding bipolar gradient (difference) function, without acceleration contribution. Any attempt to interpret the measured phase shift in terms of velocity on any other time point than the gradient gravity point will automatically introduce acceleration sensitivity.
Abstract Background User‐independent quantitative measures of cutaneous allergic reactions can help the physicians manage and evaluate the treatment of cutaneous allergic reactions. In this paper, we present and validate a method to quantify the elevation, volume and area of cutaneous allergic reactions to red tattoos. Methods The skin surface of allergic tattoo reactions was imaged using an optical 3D scanner. The in‐house developed analysis tool measured the elevation, volume and area of the lesions, compared to a reference surface. This reference surface was created by 3D interpolation of the skin after manual removal of the lesions. The error of the interpolation tool was validated using a digital arm model. The error of our optical scanner was determined using a 3D printed lesion phantom. The clinical feasibility of the method was tested in 83 lesions in 17 patients. Results The method showed clear potential to assess skin elevation, volume change and area of an allergic reaction. The validation measurements revealed that the error due to interpolation increases for larger interpolation areas and largely determined the error in the clinical measurements. Lesions with a width ≥4 mm and an elevation ≥0.4 mm could be measured with an error below 26%. Patient measurements showed that lesions up to 600 mm 2 could be measured accurately, and elevation and volume changes could be assessed at follow‐up. Conclusion Quantification of cutaneous allergic reactions to red tattoos using 3D optical scanning is feasible and may objectify skin elevation and improve management of the allergic reaction.
Dynamic contrast enhanced (DCE) MRI has become a useful technique for measuring perfusion in many applications. !e theoretical basis for perfusion quantication is the central volume principle, which requires deconvolution of the measured arterial input and tissue concentration curves to derive a residue function (R) and mean blood perfusion. Deconvolution methods generally di#er in assumptions of the global shape of R, computational stability and oscillations in estimated R. !erefore, several deconvolution methods to estimate R and blood perfusion are evaluated in this study. Among these are model-dependent and model-independent techniques. All methods were applied to series of Monte Carlo simulations to evaluate the accuracy to reproduce di#erent underlying shapes of R and blood perfusion. Of the model-independent approaches the use of B-splines with Tikhonov regularization had a reasonable accuracy in perfusion estimations and was less biased than all model-dependent approaches. !is technique is most promising for application to experimental data.
Abstract Background Late gadolinium enhanced (LGE) cardiac magnetic resonance (CMR) imaging serves as a valuable non-invasive tool for visualizing and quantifying left atrial (LA) fibrosis in atrial fibrillation (AF) patients. The extent of pre-procedural LA-LGE, indicative of native atrial fibrosis, has proven to be a predictor of AF recurrence risk following AF ablation. Consequently, assessing the LA fibrotic burden has emerged as a potential guide for personalized patient management. Currently, most centers engaged in LA-LGE image acquisition apply a scan protocol based on a diaphragmatic navigator-gated 3D image strategy (dNAV). Recently introduced image navigated (iNAV) 3D LGE strategies are proposed to outperform the dNAV strategy. This advancement involves the dynamic tracking of the heart's respiratory position with an image reconstruction algorithm, yielding motion-compensated images in significantly reduced and more consistent scan durations. We performed an evaluation of the novel image navigated (iNAV) 3D LGE-CMR imaging strategy in comparison to the conventional diaphragm navigated (dNAV) 3D LGE-CMR strategy. Methods In twenty-six consecutive AF patients, both imaging techniques (i.e. iNAV and dNAV) were performed subsequently, with equivalent spatial resolution and timing in the cardiac cycle. Patients were randomized in the acquisition order of iNAV and dNAV. LA fibrosis was quantified (percentage of atrial fibrosis using image intensity ratio threshold 1.2) and overlap in atrial fibrosis areas was tested between the two methods. Results Acquisition time of iNAV was significantly lower compared to dNAV (5±1 minutes vs. 12±4 minutes, p<0.001, respectively). There was a significant correlation between the iNAV and dNAV LA fibrotic burden (r=0.69, p<0.001). LA fibrosis scores were lower for iNAV compared to dNAV (12±8% vs. 20±12%, p<0.001, respectively). Spatial correspondence between the atrial fibrosis maps was modest (Dice similarity coefficient 0.43±0.15). Notably, 13/23 (56%) patients underwent a shift in their UTAH fibrosis stage classification, depending on the chosen imaging strategy. Conclusion iNAV acquisition was more than twice as fast as dNAV, and iNAV resulted in a lower atrial fibrosis score as compared to dNAV. More than half of the patients were reclassified into a different UTAH fibrosis stage depending on the employed imaging strategy. This underscores the critical importance of recognizing that the choice of imaging strategy significantly impacts the categorization of patients into their respective fibrosis stages. This distinction carries potential clinical implications when evaluating the utility of UTAH fibrosis stages in the context of AF management and therapeutic decision-making, as patients in lower fibrosis stages are generally regarded as more suitable candidates for ablation, while those categorized in higher fibrosis stages face an increased risk of arrhythmia recurrence following PVI.Figure 1Figure 2
In hypertrophic cardiomyopathy (HCM), autopsy studies revealed both increased focal and diffuse deposition of collagen fibers. Late gadolinium enhancement imaging (LGE) detects focal fibrosis, but is unable to depict interstitial fibrosis. We hypothesized that with T1 mapping, which is employed to determine the myocardial extracellular volume fraction (ECV), can detect diffuse interstitial fibrosis in HCM patients.
