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Background Quantitative cardiovascular magnetic resonance T1-mapping is increasingly used for myocardial tissue characterization. However, the lack of standardization limits direct comparability between centers and wider roll-out for clinical use or trials. Purpose To develop a quality assurance (QA) program assuring standardized T1 measurements for clinical use. Methods MR phantoms manufactured in 2013 were distributed, including ShMOLLI T1-mapping and reference T1 and T2 protocols. We first studied the T1 and T2 dependency on temperature and phantom aging using phantom datasets from a single site over 4 years. Based on this, we developed a multiparametric QA model, which was then applied to 78 scans from 28 other multi-national sites. Results T1 temperature sensitivity followed a second-order polynomial to baseline T1 values (R2 > 0.996). Some phantoms showed aging effects, where T1 drifted up to 49% over 40 months. The correlation model based on reference T1 and T2, developed on 1004 dedicated phantom scans, predicted ShMOLLI-T1 with high consistency (coefficient of variation 1.54%), and was robust to temperature variations and phantom aging. Using the 95% confidence interval of the correlation model residuals as the tolerance range, we analyzed 390 ShMOLLI T1-maps and confirmed accurate sequence deployment in 90%(70/78) of QA scans across 28 multiple centers, and categorized the rest with specific remedial actions. Conclusions The proposed phantom QA for T1-mapping can assure correct method implementation and protocol adherence, and is robust to temperature variation and phantom aging. This QA program circumvents the need of frequent phantom replacements, and can be readily deployed in multicenter trials., Highlights • CMR T1 correlated with reference T1 and T2; this derives the QA model for T1-map. • The proposed QA model is robust to temperature variations and phantom aging. • This QA method requires no frequent phantom replacements. • The T1-map QA program can be readily deployed in multicenter trials.

Background Quantification of absolute myocardial perfusion using positron emission tomography (PET) augments diagnostic performance and aids risk stratification in patients with coronary artery disease (CAD). Similar to PET, cardiac magnetic resonance imaging (CMR) allows for quantification of absolute myocardial blood flow (MBF). To date, quantitative CMR perfusion has not been compared with [15O]H2O PET, which is considered to be the gold standard for quantification of MBF. Purpose The purpose of this study was to compare CMR measurements of absolute myocardial perfusion to those obtained using [15O]H2O PET. Methods Fifty-one patients with stable CAD underwent [15O]H2O PET followed by CMR within 7 days. Late gadolinium enhancement was used to rule out presence of scar tissue. CMR perfusion imaging was performed using a single bolus dual sequence technique. Myocardial perfusion was quantified for the three main vascular territories at rest and during vasodilator stress. Results Pooled CMR estimates of absolute MBF correlated well with PET (r=0.79; p Per vessel – CMR vs PET perfusion Conclusions Resting MBF, stress MBF and CFR measurements correlated poorly with [15O]H2O PET. Nevertheless, stress MBF and CFR were concordant between CMR and [15O]H2O PET in 79% and 75% of vascular territories, respectively. Acknowledgement/Funding None

Contains fulltext : 209452.pdf (Publisher’s version ) (Open Access) BACKGROUND: A velocity offset error in phase contrast cardiovascular magnetic resonance (CMR) imaging is a known problem in clinical assessment of flow volumes in vessels around the heart. Earlier studies have shown that this offset error is clinically relevant over different systems, and cannot be removed by protocol optimization. Correction methods using phantom measurements are time consuming, and assume reproducibility of the offsets which is not the case for all systems. An alternative previously published solution is to correct the in-vivo data in post-processing, interpolating the velocity offset from stationary tissue within the field-of-view. This study aims to validate this interpolation-based offset correction in-vivo in a multi-vendor, multi-center setup. METHODS: Data from six 1.5 T CMR systems were evaluated, with two systems from each of the three main vendors. At each system aortic and main pulmonary artery 2D flow studies were acquired during routine clinical or research examinations, with an additional phantom measurement using identical acquisition parameters. To verify the phantom acquisition, a region-of-interest (ROI) at stationary tissue in the thorax wall was placed and compared between in-vivo and phantom measurements. Interpolation-based offset correction was performed on the in-vivo data, after manually excluding regions of spatial wraparound. Correction performance of different spatial orders of interpolation planes was evaluated. RESULTS: A total of 126 flow measurements in 82 subjects were included. At the thorax wall the agreement between in-vivo and phantom was - 0.2 +/- 0.6 cm/s. Twenty-eight studies were excluded because of a difference at the thorax wall exceeding 0.6 cm/s from the phantom scan, leaving 98. Before correction, the offset at the vessel as assessed in the phantom was - 0.4 +/- 1.5 cm/s, which resulted in a - 5 +/- 16% error in cardiac output. The optimal order of the interpolation correction plane was 1st order, except for one system at which a 2nd order plane was required. Application of the interpolation-based correction revealed a remaining offset velocity of 0.1 +/- 0.5 cm/s and 0 +/- 5% error in cardiac output. CONCLUSIONS: This study shows that interpolation-based offset correction reduces the offset with comparable efficacy as phantom measurement phase offset correction, without the time penalty imposed by phantom scans. TRIAL REGISTRATION: The study was registered in The Netherlands National Trial Register (NTR) under TC 4865 . Registered 19 September 2014. Retrospectively registered.

Item does not contain fulltext OBJECTIVE: To evaluate cardiac involvement in patients with ankylosing spondylitis using cardiac magnetic resonance (CMR). METHODS: Patients with ankylosing spondylitis without cardiovascular symptoms or known cardiovascular disease were screened by transthoracic echocardiography (TTE) for participation in this exploratory CMR study. We prospectively enrolled 15 ankylosing spondylitis patients with an abnormal TTE for further tissue characterisation using late gadolinium enhancement (LGE) and T1 mapping. T1 mapping was used to calculate myocardial extracellular volume (ECV). Disease activity was assessed by C reactive protein (CRP) and erythrocyte sedimentation rate (ESR) measurements. RESULTS: In the total of 15 included patients, 14 had a complete CMR exam (mean age 62 years, 93% male and mean disease duration 21 years). Left ventricular (LV) diastolic dysfunction was the most common finding on TTE (79%), followed by aortic root dilatation (14%), right ventricular (RV) dilatation (7%) and RV dysfunction (7%). CMR revealed focal hyperenhancement in three patients (21%), all with a particular pattern of enhancement. LV dysfunction, as defined by a LV ejection fraction below 55%, was observed in five patients (36%). Myocardial ECV was correlated with the CRP concentration (R=0.78, p

Contains fulltext : 176975.pdf (Publisher’s version ) (Open Access) 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

Purpose: To test whether image normalization using either a separate 3D proton-density (PD)-weighted prescan, or 2D PD-weighted images prior to the perfusion series, improves correction of differences in spatial sensitivity induced by radiofrequency (RF) surface receiver coils. Originally, this correction was applied using the baseline signal in the myocardium before arrival of the contrast agent. This is of importance, as quantitative analysis of magnetic resonance (MR) myocardial perfusion using deconvolution with the arterial input assumes equal signal sensitivity over the heart. Materials and Methods: First-pass myocardial perfusion measurements were obtained in 13 patients without known coronary artery disease. Absolute perfusion values were assessed for 18 myocardial segments without any normalization and using the three different normalization methods. Results: Using 2D or 3D PD-weighted normalization, similar mean perfusion values were found, but with reduced spatial variance over the 18 segments. The relative dispersion of perfusion at rest was 23% and 35% for the 3D prescan normalization and the baseline normalization, respectively. With 2D and 3D PD-weighted prescan normalization the relative dispersion was closer to the expected physiological heterogeneity. Conclusion: PD-weighted prescan normalization proved to be a valuable addition to quantitative analysis of myocardial perfusion, and better than baseline-based normalization. J. Magn. Reson. Imaging 2010;31:227–233. © 2009 Wiley-Liss, Inc.

Purpose: Cardiovascular magnetic resonance (CMR) is considered the standard imaging modality in clinical trials to monitor patients after acute myocardial infarction (AMI). However, limited data is available with respect to infarct size, presence, and extent of microvascular injury (MVO), and changes over time, in relation to cardiac function in these optimally treated patients. In this study, we prospectively investigate the change of infarct size over time, and the incidence and significance of MVO in a uniform, optimally treated patient group after AMI. Methods: Forty patients underwent cine and late gadolinium-enhanced CMR within 9 days and at 4 months after primary stenting. Left ventricular ejection fraction (LVEF), infarct size (IS) and MVO size were calculated. Results: IS decreased with 19.0% at follow-up (p < 0.01). The 23 (57.5%) patients with MVO had larger infarct size, higher left ventricular volumes and lower LVEF and more involution of IS at follow-up. Overall, LVEF improved from 42.3 ± 9.8% to 44.0 ± 9.8% (p = 0.06), irrespective of presence or size of MVO. Conclusion: Infarct size reduces over time by 19.0% in optimally treated patients after AMI. Despite optimal reperfusion, MVO was found in the majority of patients. Although patients with MVO had larger infarcts and worse indices of left ventricular remodelling, functional change at follow-up was comparable to patients without MVO.

Purpose. To evaluate a standardized definition of delayed hyperenhancement in the analysis of contrast-enhanced cardiac magnetic resonance (ceCMR) imaging. Patients and Methods. CeCMR was performed in 15 patients with chronic ischemic heart disease. Delayed hyperenhancement was analyzed both by visual analysis by an experienced team of observers, and after thresholding the window setting of the images at 2, 3, 4, 5, and 6 SD above the mean signal intensity of remote, normal myocardium in the same slice. In each patient, total infarct size (TIS) and segmental infarct extent (SIE) were calculated. Results. TIS and SIE were 22.9 ± 12.2 mL and 32 ± 28% after visual analysis. Thresholding the window setting at 2, 3, 4, and 6 SD above signal intensity of remote caused a 40%, 31%, and 17% increase (p < 0.007) and a 7% decrease (p = NS) in TIS, and a 75%, 41%, and 16% increase and 22% decrease in SIE (p < 0.001), respectively. There was no difference between visual analysis and analysis after thresholding at 5 SD. Conclusion. Analyzing ceCMR with a standardized definition of hyperenhancement related to the signal of remote, nonenhanced myocardium may result in considerable overestimation of infarct size at the usual cut-off of 2 SD.

PURPOSE: To investigate whether an existing method for correction of phase offset errors in phase-contrast velocity quantification is applicable for assessment of main pulmonary artery flow with an MR scanner equipped with a high-power gradient system.MATERIALS AND METHODS: The correction method consists of fitting a surface through the time average of stationary pixels of velocity-encoded phase images, and subtracting this surface from the velocity images. Pixels are regarded as stationary if their time standard deviation falls into the lowest percentile. Flow was measured in the main pulmonary artery of 15 subjects. Each measurement was repeated on a stationary phantom. The phase offset error in the phantom was used as a reference. Correction was applied with varying polynomial surface orders (0-5) and stationarity percentiles (5-50%). The optimal surface order and stationarity percentile were determined by comparing the fitted surface with the phantom.RESULTS: Using a first-order surface and a (noncritical) 25% percentile, the correction method significantly reduced the phase offset error from 1.1 to 0.35 cm/second (RMS), which is equivalent to a reduction from 11% to 3.3% of mean volume flow. Phase error correction strongly affected stroke volume (range -11 to 26%).CONCLUSION: The method significantly reduces phase offset errors in pulmonary artery flow.

OBJECTIVES: The aim of this study was to evaluate myocardial infarction induced by percutaneous transluminal septal myocardial ablation (PTSMA) in symptomatic patients with hypertrophic obstructive cardiomyopathy using contrast-enhanced (CE) magnetic resonance imaging (MRI). BACKGROUND: Contrast-enhanced MRI delineates the extent of myocardial infarction in coronary artery disease, but its role in ethanol-induced infarction has not been established. METHODS: Cine and CE MRI were performed before and one month after PTSMA in 24 patients. Size and location of the induced infarction were related to left ventricular (LV) mass reduction, enzyme release, volume of ethanol administered, LV outflow tract gradient reduction, and coronary ablation site. RESULTS: One month after PTSMA, regional hyperenhancement was visualized in the basal interventricular septum in all patients. Mean infarction size was 20 ± 9 g, corresponding to 10 ± 5% and 31 ± 16% of total LV and septal mass, respectively. Total LV mass decreased from 219 ± 64 to 205 ± 64 g (p < 0.01), and septal mass from 76 ± 25 to 68 ± 22 g (p < 0.01). Total LV mass reduction exceeded septal mass reduction (p < 0.01). Infarction size correlated with peak creatine phosphokinase-MB (β = 0.67, p < 0.01), volume of ethanol administered (β = 0.47, p = 0.02), total LV and septal mass reduction (β = 0.50, p = 0.02; β = 0.73, p < 0.01), and gradient reduction (β = 0.63, p < 0.01). Seven patients with exclusively right-sided septal infarction had smaller infarction size and less gradient reduction than remaining patients with left-sided or transmural infarction (p < 0.01). In five of these, PTSMA was performed distal in the target artery. CONCLUSIONS: Contrast-enhanced MRI allowed detailed evaluation of size and location of septal myocardial infarction induced by PTSMA. Infarction size correlated well with clinical indexes of infarct size.

OBJECTIVES: We evaluated whether delayed contrast-enhanced magnetic resonance imaging (DCE-MRI) using an extracellular contrast agent could predict improvement of dysfunctional but viable myocardium after acute reperfused myocardial infarction (MI). BACKGROUND: The transmural extent of hyperenhancement at DCE-MRI has been related to improvement of function in reperfused MI. However, evidence is still limited, and earlier reports have produced conflicting results regarding the significance of contrast patterns after infarction. METHODS: Thirty patients (mean age 59 ± 11 years, 27 males) underwent cine MRI and DCE-MRI 7 ± 3 days after a first reperfused acute MI and follow-up cine MRI at 13 ± 3 weeks. Segmental wall thickening and segmental extent of hyperenhancement were scored in 1,689 segments. RESULTS: Of 500 dysfunctional segments, 273 (55%) improved at follow-up. There was no difference in likelihood of improvement or complete functional recovery between segments with 0% and 1% to 25% hyperenhancement. The likelihood of improvement of segments without hyperenhancement was 2.9, 14.3, and 20 times higher than that of segments with 26% to 50%, 51% to 75%, and >75% hyperenhancement, respectively (p < 0.001). The likelihood of complete functional recovery of segments without hyperenhancement was 3.8, 11.1, and 50 times higher than that of segments with 26% to 50%, 51% to 75%, and >75% hyperenhancement, respectively (p < 0.001). CONCLUSIONS: In patients with recent reperfused MI, functional improvement of stunned myocardium is predicted by DCE-MRI.

Objectives: We sought to compare contrast-enhanced magnetic resonance imaging (ceMRI) with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic isch...

Several gradient-echo fMRI blood oxygenation level-dependent (BOLD) effects are described in the literature: extravascular spin dephasing around capillaries and veins, intravascular phase changes, and transverse relaxation changes of blood. This work considers a series of tissue compartmentalized models incorporating each of these effects, and tries to determine the model which is most consistent with the data. To isolate the different tissue contributions, a series of multi-echo inversion recovery (IR) fMRI scans were performed. Visual stimulation experiments were performed at 1.5 T, one interleaved six-echo and two IR six-echo EPI scans (the latter to suppress gray matter (GM) and cerebrospinal fluid (CSF)). The tissue and vascular composition of activated areas was analyzed using independent spin-echo IR MRI experiments and MR venography, respectively. This information was used to fit the multi-echo fMRI data to the BOLD models. The activated areas almost always included a venous vessel visible on the venogram and consisted of GM and CSF. The fMRI signal changes were best described by extravascular dephasing effects in both GM and CSF around a venous vessel, in combination with intravascular effects. The role of spin dephasing around capillaries in GM appears to be insignificant. Magn Reson Med 45:233-246, 2001.

There is clear evidence in the literature that conventional spin-echo and gradient-echo magnetic resonance imaging (MRI) is capable of assessing patency of coronary artery vein grafts. With more recently introduced breath-hold two-dimensional (2D) and contrast-enhanced 3D techniques, the predictive accuracy has further improved, with sensitivities and specificities in the 90% range. Limitations arise with regard to assessing obstructive disease and evaluating distal segments of sequential grafts, due to insufficient spatial resolution, low signal-to-noise ratio, and cardiac motion. Imaging of arterial grafts is complicated by the metallic clip artifacts. Adding information on graft flow patterns and flow reserve using velocity-encoded cine MRI may help to reduce some of the problems. Clinically, these functional measurements may become of use in non-invasive monitoring of gradually increasing graft narrowing. However, apart from a few exceptions, most patients undergo evaluation of their grafts because they are considered for a re-intervention by angioplasty or coronary artery bypass graft surgery. In these cases information on the status of the native coronary arteries is required. A broader clinical use of MRI in the evaluation of patients with coronary artery bypass grafts may therefore only be expected with further improvement in MR techniques for coronary angiography. J. Magn. Reson. Imaging 1999;10:734-740.

The ability of a blood pool contrast agent to enhance MR coronary angiography was defined. The proximal coronary vessels of pigs were imaged before and after administration of Gd-DTPA bound covalently to bovine serum albumin (0.2 mmol/kg). The contrast agent resulted in a reduction of the blood T1 value to 33 ± 5 msec, as determined in vivo with a Look-Locker technique. Both 2D and 3D imaging techniques were performed. An inversion pulse suppressed the signal of nonblood tissue postcontrast. After contrast agent administration, in the 3D data set the signal-to-noise ratio (SNR) of blood and contrast-to-noise ratio (CNR) of blood to myocardium were improved by factors of 2.0 ± 0.2 and 15 ± 8, respectively (P < 0.05). Postcontrast, the 3D acquisition was superior to the 2D technique in terms of spatial resolution, SNR of blood, and CNR of blood to myocardium. The high contrast of the 3D data set allowed for direct and rapid display of coronary arteries using a “closest vessel projection.”Magn Reson Med 41:360–367, 1999. © 1999 Wiley-Liss, Inc.

Motion of the coronary arteries during the heart cycle can result in image blurring and inaccurate flow quantification by MR. This condition applies particularly for longer acquisition windows that are typical of breath-hold coronary flow measurements. To determine the sensitivity of the technique to in-plane motion of different coronary arteries, the temporal variation in coronary position was measured in a plane perpendicular to the proximal portion of the vessel. The results indicated the presence of substantial displacement of the coronary arteries within the cardiac cycle, with a magnitude of motion approximately twice as large for the right as for the left coronary arteries. An estimation of the resulting vessel blurring was calculated, showing that the duration of the acquisition window for high spatial resolution coronary flow acquisitions should be less than 25 to 120 msec, depending on the specific coronary artery studied. In addition, these data specify optimal acquisition window placement for high resolution coronary angiography.

Background 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. Methods T1 mapping with a modified Look-Locker Inversion Recovery (MOLLI) pulse sequence was used to calculate ECV in manifest HCM (n = 16) patients and in healthy controls (n = 14). ECV was determined in areas where focal fibrosis was excluded with LGE. Results The total group of HCM patients showed no significant changes in mean ECV values with respect to controls (0.26 ± 0.03 vs 0.26 ± 0.02, p = 0.83). Besides, ECV in LGE positive HCM patients was comparable with LGE negative HCM patients (0.27 ± 0.03 vs 0.25 ± 0.03, p = 0.12). Conclusions This study showed that HCM patients have a similar ECV (e.g. interstitial fibrosis) in myocardium without LGE as healthy controls. Therefore, the additional clinical value of T1 mapping in HCM seems limited, but future larger studies are needed to establish the clinical and prognostic potential of this new technique within HCM.

Flow in the human right coronary artery was determined using magnetic resonance phase contrast velocity quantification. Two methods were applied to reduce respiratory motion: Imaging during breath holding, which is fast, and retrospective respiratory gating, which has a high temporal resolution (32 ms) in the cardiac cycle. Vessel cross-sectional area, through-plane velocity, and volume flow were determined in six healthy subjects. In-plane vessel displacement during the cardiac cycle, caused by cardiac contraction, was about 2-4 mm within a time frame of 32 ms in systole and early diastole. The motion resulted in blurring of images obtained during breath holding caused by the large acquisition time window (126 ms) within the cardiac cycle. Therefore, only with a high temporal resolution correct velocity images over the entire cardiac cycle could be obtained. The time- and cross-sectionally averaged velocity was 7 +/- 2 cm/s, and the volume flow was 30 +/- 10 ml/min.

The feasibility and safety of transesophageal cardiac pacing during clinical MRI at 1.5 Tesla is considered. An MRI compatible pace catheter was developed. In vitro testing showed a normal performance of the pulse generator, image artifacts that extended less than 11 mm from the catheter, and a less than 5% increase in noise. Cardiac stimulation induced by MRI was not observed and, theoretically, is not expected. Potentially, tissue around the catheter tip may become heated. This heating (ΔT) was monitored. Eight dogs were exposed to MRI during pacing. For low RF radiation exposure, a time-averaged squared B1 field below 0.08 pT2 (SAR < 0.03 W/kg), ΔT was below 1°C. For high RF radiation exposure, but at normal RF radiation specific absorption rate (0.4 W/kg), ΔT was 5°C. Thus, transesophageal atrial pacing during MRI at low RF exposure seems to be possible to perform cardiac stress studies or to correct unstable heart rates.

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.

Objectives: Additively manufactured bone models, implants and drill guides are becoming increasingly popular amongst maxillofacial surgeons and dentists. To date, such constructs are commonly manufactured using CT technology that induces ionizing radiation. Recently, ultrashort echo time (UTE) MRI sequences have been developed that allow radiation-free imaging of facial bones. The aim of the present study was to assess the feasibility of UTE MRI sequences for medical additive manufacturing (AM). Methods: Three morphologically different dry human mandibles were scanned using a CT and MRI scanner. Additionally, optical scans of all three mandibles were made to acquire a “gold standard”. All CT and MRI scans were converted into Standard Tessellation Language (STL) models and geometrically compared with the gold standard. To quantify the accuracy of the AM process, the CT, MRI and gold-standard STL models of one of the mandibles were additively manufactured, optically scanned and compared with the original gold-standard STL model. Results: Geometric differences between all three CT-derived STL models and the gold standard were

The purpose of this study was to develop a standardized method of 2D MRA of the proximal 50 mm of the major epicardial coronary arteries. Therefore the efficacy of fixed imaging planes (transverse, coronal, sagittal, 30-degree RAO equivalent, and 60-degree LAO equivalent) in imaging coronary arteries was compared to that of oblique planes defined by the operator on a previously obtained image. 3D data sets obtained by a respiratory-gated 3D MRA method in eight patients with a mean age of 57 years were studied by multiplanar reformatting. Efficacy of planes was expressed as an IOE. Fixed transverse imaging planes proved to be equally efficacious as operator-defined planes in imaging the left main (IOE 2.2 ± 1.0 vs 2.2 ± 0.9, p = NS) and LAD (IOE 6.0 ± 1.9 vs 8.2 ± 2.0, p = NS). Operator-defined planes were superior to fixed imaging planes in imaging the RCA (IOE 6.3 ± 1.2 vs 3.5 ± 1.2, p < 0.001) and the LCx (IOE 6.2 ± 2.3 vs 4.8 < 2.3, p < 0.05). On the basis of these results, a standardized 2D MRA protocol for the proximal coronary arteries was proposed. Pitfalls in interpretation of coronary MRA images were discussed.

Background The clinical significance of anomalously originating coronary arteries depends on their proximal course. Diagnosis of this course by conventional x-ray coronary angiography alone may be equivocal. We postulated that with fast magnetic resonance (MR) angiography, accurate detection of anomalous coronary arteries and unambiguous delineation of their proximal course is feasible. Methods and Results In a selected group of 38 patients, 19 of them having an anomalously originating coronary artery, a fast MR angiographic technique was used to study the proximal coronary anatomy. Blinded analysis of randomly ordered MR studies was performed independently by two observers. Both origin and proximal course of the coronary arteries were defined. Two cardiologists reviewed all x-ray coronary angiograms. After the separate analyses, a final consensus result was defined for each patient. In 37 patients, successful MR coronary angiography could be performed. Interobserver agreement for determining both origin and proximal course was 100%. An x-ray coronary angiogram was available in 36 patients. In 3 patients (all with an anomalous left main coronary artery originating from the right aortic sinus), there was disagreement about the proximal course between the results of MR and x-ray coronary angiography. Review of these cases demonstrated that MR angiography had unambiguously visualized the proximal coronary artery course, whereas the results of x-ray angiography had been equivocal. Thus, sensitivity and specificity for detecting anomalous coronary arteries and delineating their proximal course were 100%. Conclusions These data suggest that fast MR angiography is highly accurate in determining the origin and delineating the proximal course of anomalous coronary arteries, even in those cases in which x-ray coronary angiographic diagnosis is difficult or even erroneous.

Amyloidosis is a systemic infiltrative disorder in which insoluble protein fibrils are deposited in the extracellular matrix (ECM). The prognosis is predominantly determined by cardiac involvement because the amyloid depositions lead to a restrictive cardiomyopathy. Although endomyocardial biopsy is the gold standard for diagnosing cardiac amyloidosis, the associated risk for complications favors a noninvasive approach by using various cardiac imaging methods, whereas tissue diagnosis is made on a noncardiac biopsy. Accurate diagnosis of cardiac amyloidosis becomes difficult when a secondary cause of myocardial wall thickening (eg, hypertension) is present as well. Cardiac MRI is an excellent tool for assessment of systolic and diastolic function, myocardial thickness, and amyloid deposition with late gadolinium enhancement imaging.1 Late gadolinium enhancement imaging is a qualitative technique, which relies on the presence of normal myocardium to visualize infiltrated, enhanced tissue. Therefore, diffuse deposition of amyloid is difficult to highlight, because regional differences in signal intensities may be absent. T1-mapping is a cardiac MR technique, which allows absolute quantification of T1 values of the myocardium and enables assessment of ECM expansion present in cardiac amyloidosis. A 71-year-old man with a medical history of hypertension presented with suspicion of congestive heart failure. A 12-lead electrocardiography showed atrial fibrillation and low voltages in the …

Background Phase-contrast velocity images often contain a background or baseline offset error, which adds an unknown offset to the measured velocities. For accurate flow measurements, this offset must be shown negligible or corrected. Some correction techniques depend on replicating the clinical flow acquisition using a uniform stationary phantom, in order to measure the baseline offset at the region of interest and subtract it from the clinical study. Such techniques assume that the background offset is stable over the time of a patient scan, or even longer if the phantom scans are acquired later, or derived from pre-stored background correction images. There is no published evidence regarding temporal stability of the background offset. Methods This study assessed the temporal stability of the background offset on 3 different manufacturers’ scanners over 8 weeks, using a retrospectively-gated phase-contrast cine acquisition with fixed parameters and at a fixed location, repeated 5 times in rapid succession each week. A significant offset was defined as 0.6 cm/s within 50 mm of isocenter, based upon an accuracy of 10% in a typical cardiac shunt measurement. Results Over the 5 repeated cine acquisitions, temporal drift in the baseline offset was insignificant on two machines (0.3 cm/s, 0.2 cm/s), and marginally insignificant on the third machine (0.5 cm/s) due to an apparent heating effect. Over a longer timescale of 8 weeks, insignificant drift (0.4 cm/s) occurred on one, with larger drifts (0.9 cm/s, 0.6 cm/s) on the other machines. Conclusions During a typical patient study, background drift was insignificant. Extended high gradient power scanning with work requires care to avoid drift on some machines. Over the longer term of 8 weeks, significant drift is likely, preventing accurate correction by delayed phantom corrections or derivation from pre-stored background offset data.

Summary Robust pre-contrast reference T1 values using ShMOLLI in 231 normal human controls aged 11 to 81 years demonstrate little dependence on gender, age or heart rates. Background Quantitative T1-mapping is rapidly becoming a clinical Cardiovascular Magnetic Resonance (CMR) imaging tool that can distinguish normal from diseased myocardium. The usefulness of any quantitative measurement to identify disease lies in its ability to detect significant differences from an established normal range of values. In this study we aim to establish a large database for the normal range of T1 values in healthy human myocardium and to examine any differences based on age and gender.

Purpose: Eddy current induced velocity offsets are of concern for accuracy in cardiovascular magnetic resonance (CMR) volume flow quantification. However, currently known theoretical aspects of eddy current behavior have not led to effective guidelines for the optimization of flow quantification sequences. This study is aimed at identifying correlations between protocol parameters and the resulting velocity error in clinical CMR flow measurements in a multi-vendor study. Methods: Nine 1.5T scanners of three different types/vendors were studied. Measurements were performed on a large stationary phantom. Starting from a clinical breath-hold flow protocol, several protocol parameters were varied. Acquisitions were made in three clinically relevant orientations. Additionally, a time delay between the bipolar gradient and read-out, asymmetric versus symmetric velocity encoding, and gradient amplitude and slew rate were studied in adapted sequences as exploratory measurements beyond the protocol. Image analysis determined the worst-case offset for a typical great-vessel flow measurement. Results: The results showed a great variation in offset behavior among scanners (standard deviation among samples of 0.3, 0.4, and 0.9 cm/s for the three different scanner types), even for small changes in the protocol. Considering the absolute values, none of the tested protocol settings consistently reduced the velocity offsets below the critical level of 0.6 cm/s neither for all three orientations nor for all three scanner types. Using multilevel linear model analysis, oblique aortic and pulmonary slices showed systematic higher offsets than the transverse aortic slices (oblique aortic 0.6 cm/s, and pulmonary 1.8 cm/s higher than transverse aortic). The exploratory measurements beyond the protocol yielded some new leads for further sequence development towards reduction of velocity offsets; however those protocols were not always compatible with the time-constraints of breath-hold imaging and flow-related artefacts. Conclusions: This study showed that with current systems there was no generic protocol which resulted into acceptable flow offset values. Protocol optimization would have to be performed on a per scanner and per protocol basis. Proper optimization might make accurate (transverse) aortic flow quantification possible for most scanners. Pulmonary flow quantification would still need further (offline) correction. This is an electronic version of an article published in: Marijn P Rolf, Mark B M Hofman, Pete rD Gatehouse, Karin Markenroth-Bloch, Martijn W Heymans, Tino Ebbers, Martin J Graves, John J Totman, Beat Werner, Albert C van Rossum, Philip J Kilner and Rob M Heethaar, Sequence optimization to reduce velocity offsets in cardiovascular magnetic resonance volume flow quantification - A multi-vendor study, 2011, JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE, (13). JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE is available online at informaworldTM: http://dx.doi.org/10.1186/1532-429X-13-18 Licensee: Taylor & Francis / BioMed Central http://www.tandf.co.uk/journals/default.asp

Background Quantification of abdominal blood flow is essential for a variety of gastrointestinal and hepatic topics such as liver transplantation or metabolic flux measurement, but those need to be performed during surgery. It is not clear whether Duplex Doppler Ultrasound during surgery or MRI before surgery is the tool to choose. Objective To examine whether preoperative evaluation of abdominal blood flow using MRI could prove to be a useful and reliable alternative for the perioperative sonographic approach. Methods In this study portal and renal venous flow and hepatic arterial flow were sequentially quantified by preoperative MRI, preoperative and perioperative Duplex Doppler Ultrasound (DDUS). 55 Patients scheduled for major abdominal surgery were studied and methods and settings were compared. Additionally, average patient population values were compared. Results Mean (±SD) plasmaflow measured by perioperative DDUS, preoperative DDUS and MRI, respectively was 433 ± 200/423 ± 162/507 ± 96 ml/min (portal vein); 96 ± 70/74 ± 41/108 ± 91 ml/min (hepatic artery); 248 ± 139/201 ± 118/219 ± 69 ml/min (renal vein). No differences between the different settings of DDUS measurement were detected. Equality of mean was observed for all measurements. Bland Altman Plots showed widespread margins. Hepatic arterial flow measurements correlated with each other, but portal and renal venous flow correlations were absent. Conclusions Surgery and method (DDUS vs. MRI) do not affect mean flow values. Individual comparison is restricted due to wide range in measurements. Since MRI proves to be more reliable with respect to inter-observer variability, we recommend using mean MRI results in experimental setups.

The combined use of cardiac computed tomography coronary angiography (CTCA) and myocardial perfusion imaging allows the non-invasive evaluation of coronary morphology and function. Cardiovascular magnetic resonance imaging (CMR) has several advantages: it can simultaneous assess myocardial perfusion, ventricular and valvular function, cardiomyopathy and aortic disease and does not involve any ionizing radiation.

Magnetic resonance imaging (MRI) is a non-invasive modality which can be used for direct visualization of coronary artery bypass grafts. Spin-echo and gradient-echo (cine-MRI) techniques are now available on standard MR machines and provide information on graft morphology and graft patency with a 90% accuracy. By combining the standard techniques with MR phase velocity mapping, the flow rate in the graft can be measured, thereby offering a unique non-invasive assessment of the graft function. Newer techniques include MR coronary angiography, pharmacologically induced stress MRI, ultrafast MRI of the first-pass (perfusion) of a paramagnetic contrast agent through the myocardium, and31P MR spectroscopy of high-energy phosphate metabolism of the myocardium. All of these may develop into valuable diagnostic tools for the assessment of functional results after CABG or PTCA, but still require clinical validation. At present, MRI is a useful screening procedure for assessment of graft patency and function in post-operative pain syndromes and in late graft occlusion or stenosis.

This report evaluates several methods to estimate blood perfusion and residue functions in dynamic contrast enhanced (DCE) MRI. Among these are model-dependent and model-independent techniques. All methods were applied to series of Monte Carlo simulations to evaluate the accuracy in order to reproduce different underlying vascular residue functions and blood perfusions. Of the model-independent approaches the use of B-splines with Tikhonov regularization was shown to have a reasonable accuracy in blood perfusion estimations and was less biased than all model-dependent approaches. This technique seems most promising for application to experimental data.

Purpose: To investigate the incremental diagnostic value of dual-bolus over single-contrast-bolus first pass magnetic resonance myocardial perfusion imaging (MR-MPI) for detection of significant coronary artery disease (CAD). Materials and Methods: Patients (n = 49) with suspected CAD underwent first pass adenosine stress and rest MR-MPI and invasive coronary angiography (CA). Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was injected with a prebolus (1 mL) and a large bolus (0.1 mmol/kg). For the single-bolus technique, the arterial input function (AIF) was obtained from the large-contrast bolus. For the dual-bolus technique, the AIF was reconstructed from the prebolus. Absolute myocardial perfusion was calculated by Fermi-model constrained deconvolution. Receiver operating characteristic (ROC) analysis was used to investigate diagnostic accuracy of MR myocardial perfusion imaging for detection of significant CAD on CA at vessel-based analysis. Results: The area under the curve (AUC) of the minimal stress perfusion value for the detection of significant CAD using the single-bolus and dual-bolus technique was 0.85 ± 0.04 (95% confidence interval [CI], 0.77–0.93) and 0.77 ± 0.05 (95% CI, 0.67–0.86), respectively. Conclusion: In this study the dual-bolus technique had no incremental diagnostic value over single-bolus technique for detection of significant CAD with the used contrast concentrations. J. Magn. Reson. Imaging 2010;32:88–93. © 2010 Wiley-Liss, Inc.

Purpose: To evaluate which cardiac magnetic resonance (MR) imaging technique for detection of microvascular obstruction (MVO) best predicts left ventricular (LV) remodeling after acute myocardial infarction (MI). Materials and Methods: This study had local ethics committee approval; all patients gave written informed consent. Sixty-three patients with first acute MI, treated with primary stent placement and optimal medical therapy, underwent cine MR imaging at 4-7 days and at 4 months after MI. Presence of MVO was qualitatively evaluated at baseline by using three techniques: (a) a single-shot saturation-recovery gradient-echo first-pass perfusion sequence (early hypoenhancement), mean time, 1.09 minutes +/- 0.07 (standard deviation) after contrast material administration; (b) a three-dimensional segmented saturation-recovery gradient-echo sequence (intermediate hypoenhancement), mean time, 2.17 minutes +/- 0.26; and (c) a two-dimensional segmented inversion-recovery gradient-echo late gadolinium enhancement sequence (late hypoenhancement), mean time, 13.32 minutes +/- 1.26. Contrast-to-noise ratios (CNRs) were calculated from the signal-to-noise ratios of the infarcted myocardium and MVO areas. Univariable linear regression analysis was used to identify the predictive value of each MR imaging technique. Results: Early hypoenhancement was detected in 44 (70%) of 63 patients; intermediate hypoenhancement, in 39 (62%); and late hypoenhancement, in 37 (59%). Late hypoenhancement was the strongest predictor of change in LV end-diastolic and end-systolic volumes over time (beta = 14.3 , r = 0.40, P = .001 and beta = 11.3, r = 0.44, P

As computed tomography coronary angiography (CTCA) has a reported excellent negative predictive value for detection of significant coronary artery disease (CAD), it is increasingly used as first line technique in the evaluation of patients with suspected CAD. However, positive predictive value is low and CTCA lacks information about myocardial perfusion. As first pass magnetic resonance myocardial perfusion imaging (MRMPI) can accurately assess myocardial perfusion and does not involve ionizing radiation, it may be a valuable additional technique to CTCA in the evaluation of patients with suspected CAD. Subsequently, their combined use may lower the number of unnecessary, costly invasive coronary angiographies (CAG).

Cardiovascular magnetic resonance is considered the standard imaging modality in clinical trials to monitor patients after acute myocardial infarction. However, limited data are available with respect to infarct size, presence and extent of microvascular injury (MVO) and changes over time, in relation to cardiac function in optimally treated patients. In the current study we prospectively investigate the change of infarct size over time, and the incidence and significance of MVO in a uniform, optimally treated patient group after AMI. (Neth Heart J 2008;16:179-81.18566669)

PURPOSE: To evaluate safety and image quality of cardiovascular magnetic resonance (CMR) at 3.0 T in patients with coronary stents after myocardial infarction (MI), in comparison to the clinical standard at 1.5 T. METHODS: Twenty-five patients (21 men; 55 +/- 9 years) with first MI treated with primary stenting, underwent 18 scans at 3.0 T and 18 scans at 1.5 T. Twenty-four scans were performed 4 +/- 2 days and 12 scans 125 +/- 23 days after MI. Cine (steady-state free precession) and late gadolinium-enhanced (LGE, segmented inversion-recovery gradient echo) images were acquired. Patient safety and image artifacts were evaluated, and in 16 patients stent position was assessed during repeat catheterization. Additionally, image quality was scored from 1 (poor quality) to 4 (excellent quality). RESULTS: There were no clinical events within 30 days of CMR at 3.0 T or 1.5 T, and no stent migration occurred. At 3.0 T, image quality of cine studies was clinically useful in all, but not sufficient for quantitative analysis in 44% of the scans, due to stent (6/18 scans), flow (7/18 scans) and/or dark band artifacts (8/18 scans). Image quality of LGE images at 3.0 T was not sufficient for quantitative analysis in 53%, and not clinically useful in 12%. At 1.5 T, all cine and LGE images were quantitatively analyzable. CONCLUSION: 3.0 T is safe in the acute and chronic phase after MI treated with primary stenting. Although cine imaging at 3.0 T is suitable for clinical use, quantitative analysis and LGE imaging is less reliable than at 1.5 T. Further optimization of pulse sequences at 3.0 T is essential

Purpose To discuss differences between displacement encoding with stimulated echoes (DENSE) and the harmonic phase (HARP) in imaging and reconstruction strategies. Materials and Methods HARP and DENSE are presented in their historical context: while the HARP method was developed from the framework of myocardial tagging, DENSE arose from the framework of stimulated echo and displacement encoding using bipolar gradients. Both techniques have evolved since their introduction, thereby becoming more similar over time and losing their distinct features. Newly introduced improvements have successfully been applied in both methods. Differences between both methods are discussed point by point. Results From this discussion it follows that almost all apparent differences are in fact nonexistent. Conclusion In the literature, both techniques are still regarded as distinctly different techniques, where a more general treatment of the technique is justified. Once it is realized that both frameworks are easily merged, the benefits are 1) less confusion about the (dis)advantages of either technique, and 2) understanding of phase-based strain imaging that is more general than HARP or DENSE alone. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.

Background— Alcohol septal ablation (ASA) reduces left ventricular outflow tract (LVOT) pressure gradient in patients with hypertrophic obstructive cardiomyopathy (HOCM), which leads to left ventricular remodeling. We sought to describe the early to midterm changes and modulating factors of the remodeling process using cardiac MRI (CMR). Methods and Results— CMR was performed at baseline and 1 and 6 months after ASA in 29 patients with HOCM (age 52±16 years). Contrast-enhanced CMR showed no infarct-related hyperenhancement outside the target septal area. Septal mass decreased from 75±23 g at baseline to 68±22 and 58±19 g ( P P P =0.03). Conclusions— Left ventricular remodeling after ASA occurs early and progresses on midterm follow-up, modulated by CMR infarct size and location. Remote mass reduction is associated with infarct location and correlates with reduction of the LVOT pressure gradient. Thus, myocardial hypertrophy in HOCM is, at least in part, afterload dependent and reversible and is not exclusively caused by the genetic disorder.

Contrast-enhanced magnetic resonance (MR) imaging allows detection of nonviable myocardium. The authors compared a one-breath-hold three-dimensional inversion-recovery gradient-echo MR sequence with a multiple-breath-hold two-dimensional inversion-recovery gradient-echo MR sequence for the detection of nonviable myocardium. On the basis of a quantitative and qualitative approach, total myocardial area and contrast material-enhanced area, as well as the presence and spatial extent of hyperenhancement, were analyzed separately for each MR image obtained with each sequence in 10 patients with chronic ischemic heart disease. Findings for total myocardial area and contrast-enhanced area agreed well between the two sequences. A high level of agreement was also found for the presence of hyperenhancement (kappa = 0.84), while agreement was poor for the transmural extent of hyperenhancement (kappa = 0.32), which was attributed to the blurred appearance of the three-dimensional MR images. Findings with the one-breath-hold three-dimensional MR sequence allow assessment of nonviable myocardium with good agreement with those with the multiple-breath-hold two-dimensional MR sequence.

OBJECTIVES: The purpose of this study was to assess the value of cardiovascular magnetic resonance (CMR)-determined graft flow and flow reserve in differentiating significant from non-significant vein graft disease. BACKGROUND: In patients after coronary artery bypass grafting (CABG), non-invasive testing may be helpful in the detection of recurrent graft disease. METHODS: Randomly selected patients (n = 21) scheduled for X-ray angiography because of recurrent chest complaints after CABG were included for evaluation of vein grafts (n = 40) by CMR. Three-dimensional contrast-enhanced CMR angiography was performed and followed by flow measurements at rest and during hyperemia in patent grafts only. Flow reserve was calculated when resting flow exceeded 20 ml/min. Analysis was based on four categories defined by X-ray angiography: occluded grafts (n = 3), grafts with stenosis >50% (n = 19), grafts with stenosis 50% and normal run-off (n = 10). RESULTS: The CMR angiography demonstrated occlusion of three grafts. In nine of the 37 patent grafts, basal blood flow was 20 ml/min (n = 28), flow reserve significantly differed between grafts without stenosis and grafts with significant stenosis or with diseased run-off (2.5 ± 0.7 vs. 1.8 ± 0.9, p = 0.04). An algorithm combining basal volume flow

Magnetic resonance (MR) flow mapping can be used to quantify flow velocity and volume flow in the coronary vessels noninvasively. The close anatomic relationship of the left anterior descending artery (LAD) with the great cardiac vein (GCV) allows imaging of both in one view. We examined the feasibility to discriminate between these two vessels based on the flow pattern and to measure the flow quantitatively. Eleven individuals with a normal LAD and 8 patients with a diseased LAD underwent MR imaging. From MR angiograms using connectivity to the aortic root, differentiation between the LAD and GCV was obtained. Perpendicular to both vessels, phase-contrast velocity mapping was performed to measure phasic and mean volume flow. After correction for cardiac motion of the vessel, GCV flow was found to be mainly systolic and pointing in the inverse direction as the predominantly diastolic flow in the LAD. These criteria appeared valid in all subjects, even in cases of highly stenotic arteries. The volume flow measurements corrected for body surface area were 31 ± 15 ml/min/m2 in the normal LAD (n = 11) and 21 ± 10 ml/min/m2 in the diseased LAD (n = 7). The volume flow measurements in the GCV corrected for body surface area were 23 ± 19 ml/min/m2 in the normal vessels and 19 ± 16 ml/min/m2 in the diseased vessels. In the patient with an occluded LAD and collaterals, the volume flow in the GCV was 7 ml/min/m2. MR is a unique tool for noninvasive simultaneous measurement of the flow pattern and volume flow in the GCV and the LAD, showing a clear distinction between arterial and venous flow.

The purpose of this study was to investigate the feasibility of first-pass MR imaging for measurement of regional myocardial blood flow in human beings. The first pass of the contrast agent Gd-DTPA through the myocardium was imaged in 12 normal volunteers with an EGG-gated Turbo-Flash sequence. The MTT of the contrast agent through the myocardium after a bolus injection was derived from curves of SI versus time. The bolus was injected through an intravenous catheter, which was advanced to the central venous position (preferably the right atrium). To investigate myocardial input function, different bolus concentrations and catheter positions were compared. It is concluded that first-pass MR imaging is feasible in human subjects when a central injection of 0.03 mmol/kg of Gd-DTPA is applied. MTT values were similar throughout the myocardium of normal subjects at rest, reflecting normal perfusion. Absolute values of MTT were related to the myocardial input.

The feasibility of the determination of the time-average of pulsatile velocity obtained via a nontriggered magnetic resonance (MR) acquisition is studied. The advantage of this method, in comparison with a triggered acquisition, is a considerable reduction (approximately 15x) in acquisition time. However, pulsatility causes image artifacts, known as ghosts, and the Fourier transform technique required for the imaging procedure accomplishes time-averaging of the complex MR signal. Both effects can result in errors in the velocity determined. Calculations show that these errors depend on the velocity time function and the acquisition parameters. In vivo comparison of triggered and nontriggered MR velocity measurements in the femoral artery of volunteers (n = 7) shows larger statistical and systematic errors in the latter, which depend on the excitation angle. Therefore, this nontriggered average velocity measurement is only useful as a fast and rough estimation of the time-averaged velocity.

Aims Cardiovascular magnetic resonance (CMR) allows non-invasive phase contrast measurements of flow through planes transecting large vessels. However, some clinically valuable applications are highly sensitive to errors caused by small offsets of measured velocities if these are not adequately corrected, for example by the use of static tissue or static phantom correction of the offset error. We studied the severity of uncorrected velocity offset errors across sites and CMR systems. Methods and Results In a multi-centre, multi-vendor study, breath-hold through-plane retrospectively ECG-gated phase contrast acquisitions, as are used clinically for aortic and pulmonary flow measurement, were applied to static gelatin phantoms in twelve 1.5 T CMR systems, using a velocity encoding range of 150 cm/s. No post-processing corrections of offsets were implemented. The greatest uncorrected velocity offset, taken as an average over a 'great vessel' region (30 mm diameter) located up to 70 mm in-plane distance from the magnet isocenter, ranged from 0.4 cm/s to 4.9 cm/s. It averaged 2.7 cm/s over all the planes and systems. By theoretical calculation, a velocity offset error of 0.6 cm/s (representing just 0.4% of a 150 cm/s velocity encoding range) is barely acceptable, potentially causing about 5% miscalculation of cardiac output and up to 10% error in shunt measurement. Conclusion In the absence of hardware or software upgrades able to reduce phase offset errors, all the systems tested appeared to require post-acquisition correction to achieve consistently reliable breath-hold measurements of flow. The effectiveness of offset correction software will still need testing with respect to clinical flow acquisitions., Journal of Cardiovascular Magnetic Resonance, 12, ISSN:1097-6647, ISSN:1532-429X

Velocity and volumetric flow of left ventricular venous outflow in the distal coronary sinus were measured with magnetic resonance (MR) velocity mapping techniques in 24 healthy men. A total of 16-21 velocity maps were acquired throughout the cardiac cycle. To determine the accuracy of the MR velocity-mapping pulse sequence, measurements were obtained with a flow phantom. Mean blood flow was 144 mL/min ± 62 (standard deviation); mean velocity, 2.1 cm/sec ± 1.0; and mean cross-sectional area, 1.2 cm2. Phasic measurements revealed a biphasic flow pattern in the coronary sinus, with a first peak in systole (257 mL/min ± 174) and a second peak in early diastole (1,090 mL/min ± 487). The cross-sectional area varied between 0.5 cm2 ± 0.2 at end diastole and 1.9 cm2 ± 0.6 in systole, a finding that suggests a capacitance function for venous outflow. Mean blood flow measurements were in agreement with measurements obtained invasively in previous studies. It is concluded that MR velocity mapping can enable noninvasive measurement of coronary venous outflow and global left ventricular perfusion and may become clinically useful in assessment of coronary blood flow reserve.