Blood Flow Maps Research Articles

Quantitative mapping of basal and vasareactive cerebral blood flow using split-dose 123I-iodoamphetamine and single photon emission computed tomography

A new method has been developed for diffusible tracers, to quantify CBF at rest and after pharmacological stress from a single session of dynamic scans with dual bolus administration of a radiotracer.The calculation process consisted of three steps, including the procedures of incorporating background radioactivity contaminated from the previous scan. Feasibility of this approach was tested on clinical SPECT studies on 16 subjects. Two sequential SPECT scans, 30 min apart, were carried out on each subject, after each of two split-dose administrations of 111 MBq IMP. Of these, 11 subjects received acetazolamide at 10 min before the second IMP injection. Additional PET scans were also carried out on 6 subjects on a separate day, at rest and after acetazolamide administration. The other 5 subjects were scanned only at rest during the whole study period.Quantitative CBF obtained by this method was in a good agreement with those determined with PET (y(ml/100 g/min)=1.07×(ml/100 g/min)−1.14, r=0.94). Vasareactivity was approximately 40% over the whole cerebral area on healthy controls, which was consistent with a literature value. Reproducibility of CBF determined in the rest–rest study was 1.5±5.7%. Noise enhancement of CBF images, particularly the second CBF, was reduced, providing reasonable image quality.Repeat assessment of quantitative CBF from a single session of scans with split-dose IMP is accurate, and may be applied to clinical research for assessing vascular reactivity in patients with chronic cerebral vascular disease.

P07.10: Villous blood flow mapping as a prognostic factor in IUGR pregnancy

3 and 12 IUGR pregnancies between 28 and 41 gestation week were examined in the cross sectional study. Villous arteries color Doppler flow patterns in IUGR pregnancies were related with the same pictures of uncomplicated pregnancies. Villous arteries were identified by color Doppler image of the placenta. 37 women with uncomplicated pregnancy and 12 with IUGR pregnancy between 28 and 41 gestation week were analyzed. Villous arteries were identified in the placenta structure. Presence of the blood vessels were colerated with pH level from umbilical artery after the labor and with infant condition in the Apgar scale. There was an important difference between the pH levels in group with uncomplicated pregnancy (pH = 7.31100) and the group with IUGR (pH = 7.218583). What is more, in group with IUGR two subgroups could be find: 1st with presence of villous arteries in color Doppler and 2nd without villous arteries. Important difference in pH level of umbilical blood after labor between these two subgroups were identified (pH = 7.292000 for the 1st subgroup and pH = 7.115800 for the 2nd). Important difference in Apgar grades between the group with uncomplicated pregnancy and the IUGR group were identified but the difference was not identified between the IUGR subgroups. Examining placental vessels in our investigation is an important prognostic factor differentiating the degree of limitation of blood flow in placenta. It has a strict connection with the condition of fetus and infant.

Feasibility and measurement precision of 3D quantitative blood flow mapping of the prostate using dynamic contrast-enhanced multi-slice CT

We have developed a 3D dynamic contrast-enhanced (DCE) multislice CT protocol that covers the complete prostate. The DCE-CT data are subsequently analysed using the adiabatic approximation of the tissue homogeneity model resulting in five 3D quantitative maps of blood flow, mean transit time, extraction fraction, extracellular extravascular space and delay time. The purpose of this study was to establish the feasibility of determining these parameters in the prostate with a spatial resolution as high as ∼0.1 cc as well as a good measurement precision. The precision of the parameter estimation as a function of noise level is determined by a Monte Carlo-based method that simulates the effect of noise present in the data. We find that the precision depends on the value of the flow and transit time, where a higher value is favourable. At a noise level of 4 HU in combination with a peak enhancement in the iliac arteries of ∼300 HU the 95% confidence intervals are sufficiently small to discriminate whether a parameter value is above or below a given threshold. We have collected and analysed the noise level in the DCE-data of five patients. A noise level of 3.8 HU on average can be obtained by averaging to a voxel volume of 4.5 × 4.5 × 5 mm3 = 0.1 cc. Analysis of the parameter maps shows that it is feasible to detect both small and large lesions, as well as irregularly shaped lesions.

Acute Anterior Circulation Stroke: Recanalization Using Clot Angioplasty

Different strategies have been employed to recanalize acutely occluded middle cerebral and internal carotid arteries (ICA) in the setting of acute stroke including intravenous and intra-arterial tPA. However, pharmaceutical thrombolysis alone, may not be effective in patients with a large amount of clot volume (complete M1, terminal internal carotid artery). We report our initial experience with endovascular clot disruption using a soft silicone balloon in addition to intravenous or intra-arterial thrombolysis with tPA. This is a retrospective review of nine patients with symptoms of acute stroke from clot in the middle cerebral or internal carotid territories who were treated with intracranial balloon angioplasty. All patients presented with symptoms of acute anterior circulation stroke less than six hours from onset. Patients in whom computed tomography (CT) angiography confirmed the presence of large vessel clot (terminal ICA, M1 or proximal M2) were included in the study. A CT perfusion was performed providing maps of cerebral blood volume, flow and mean transit time. If the patient presented less than three hours from onset then intravenous tissue plasminogen activator (tPA) was also administered. Intra-arterial tPA was delivered into the clot. If the volume of clot was judged to be significant by the treating neurointerventionist, then a limited trial of tPA was administered intra-arterially followed by balloon angioplasty of persistant clot. The time from imaging to vessel recanalization was recorded. Clinical outcomes were assessed using the modified Rankin scale and Barthel Index. Diagnostic CT perfusion studies were performed in 7 (78%), all of which showed a significant amount of salvageable tissue as judged by the treating neurointerventionist and neurologist. Recanalization (TIMI 2 or 3) was possible in 8 (89%). There were no cases of symptomatic intracranial hemorrhage and 2 (22%) asymptomatic hemorrhages. The average time from performance of the initial emergency CT to vessel recanalization was 2.1 hours with mean time from symptom onset to vessel recanalization of 4.1 hours. Five (56%) patients had good outcomes, 1 (11%) had mild and 3 (33%) had moderate to severe disability. Clot angioplasty can potentially shorten recanalization times in well-selected patients and can be an effective complimentary procedure in patients with tPA resistant clot. Angioplasty can be performed with a very low complication rate using the technique described and may be associated with good outcomes.

Improvement of quantification of myocardial first‐pass perfusion mapping: A temporal and spatial wavelet denoising method

Mapping of myocardial blood flow (MBF) with first-pass perfusion imaging is becoming an important tool in the study of coronary artery disease. In this study a wavelet-based denoising method was developed to improve the accuracy of pixel-by-pixel MBF maps. We performed an in vivo study in five stenotic dogs with 70% stenosis in the left coronary arteries. First-pass perfusion imaging sessions were performed by administering the intravascular contrast agent Gadomer at rest and during dipyridamole-induced vasodilation. Color microspheres (MS) were injected into the dogs to measure MBF at the same time. After denoising was performed, the signal-to-noise ratio (SNR) of the first-pass perfusion image improved by approximately 180%, whereas spatial variation of MBF maps decreased 38%. It was also found that the correlation of MBFs measured by MRI with the MS method indicates a significant improvement with the denoising method (R2 increased from 0.24 to 0.78, P < .001). This suggests that the wavelet denoising method may be an effective way to increase the accuracy of pixel-by-pixel MBF quantification and reduce spatial variation, and may be applicable to other forms of noise-sensitive image analysis.

Image quality in CT perfusion imaging of the brain

The purpose of this study was to evaluate the impact of various iodine contrast concentrations on image quality in computed tomography (CT) perfusion studies. Twenty-one patients with suspicion of cerebral ischemia underwent perfusion CT using two different iodine contrast concentrations: 11 patients received iomeprol 300 (iodine concentration: 300 mg/ml ) while ten received the same volume of iomeprol 400 (iodine concentration: 400 mg/ml). Scan parameters were kept constant for both groups. Maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and time to peak (TTP) were calculated from two adjacent slices. Quantitative comparisons were based on measurements of the maximum enhancement [Hounsfield units (HU)] and signal-to-noise index (SNI) on CBF, CBV, and TTP images. Determinations of grey-to-white-matter delineation for each iodine concentration were performed by two blinded readers. Only data from the non-ischemic hemispheres were considered. Both maximum enhancement and SNI values were higher after iomeprol 400, resulting in significantly better image quality in areas of low perfusion. No noteworthy differences were found for normal values of CBF, CBV, and TTP. Qualitative assessment of grey/white matter contrast on CBF and CBV maps revealed better performance for iomeprol 400. For brain perfusion studies, highly concentrated contrast media such as iomeprol 400 is superior to iomeprol 300.

Optimal window for ictal blood flow mapping: Insight from the study of discrete temporo-limbic seizures in rats

Rationale Measurement of local cerebral blood flow (LCBF) is routinely used to locate the areas involved in the generation and spread of seizures in epileptic patients. Since the spatial distribution and extent of ictal LCBF depends on the epileptogenic network, but also on the timing of injection of tracer, we used a rat model of amygdala kindled seizures to follow time-dependent changes in the distribution of seizure-induced LCBF changes. Methods Rats were implanted with a left amygdala electrode and were stimulated until reaching stage 1. LCBF was measured by the quantitative [ 14C]iodoantipyrine autoradiographic technique. The tracer was injected either at 15 s before seizure induction (early ictal) or simultaneously with the amygdala stimulation (ictal) in rats undergoing a stage 0 or 1 seizure. Results During stage 0 seizures, LCBF rates increased significantly ipsilaterally in medial and central amygdala and substantia nigra. During stage 1 seizures, LCBF increased unilaterally in amygdala, piriform cortex, substantia nigra, ventral tegmental area and cerebellum and bilaterally in several limbic and subcortical structures, excepted in hippocampus and pallidum. When pooling stages 0 and 1 but considering only tracer injection time, discrete LCBF changes occurred ipsilaterally in amygdala and substantia nigra at early ictal time. At true ictal time, significant changes occurred in several subcortical structures bilaterally while limbic structures displayed more localized and lateralized changes. Conclusion LCBF mapping appears unable to identify in rats the ictal onset zone of clinically significant amygdala-triggered seizures (stage 1), while the study of sub-clinical seizures (stage 0) allowed to correctly locate the amygdala onset of the seizures within the limbic network. Compared to human SPECT studies, this work confirms that some ictal hyperperfused areas belong to the spreading network rather than to the epileptogenic zone. The spatial recruitment of remote subcortical structures could be further investigated to strengthen the rationale of therapeutic stimulation of basal ganglia in drug-resistant epilepsies.

Reproducibility of Endometrial Vascular Patterns in Endometrial Disease as Assessed by Transvaginal Power Doppler Sonography in Women With Postmenopausal Bleeding

The purpose of this study was to assess the intraobserver and interobserver agreement for identifying different endometrial vascular patterns using power Doppler sonography in women with postmenopausal bleeding and a thickened endometrium. Digitally stored sonographic images from a random sample of 65 patients with postmenopausal bleeding and a thick endometrium (>5 mm) on B-mode sonography and evaluated by transvaginal power Doppler sonography for assessment of endometrial blood flow mapping were evaluated by 5 different examiners with different levels of expertise in Doppler sonography. Intraobserver and interobserver agreement according to the level of experience were assessed by calculating the kappa index. Intraobserver agreement was good or very good for all experienced examiners (kappa = 0.78-0.96) and moderate (kappa = 0.52) for the inexperienced examiner. Interobserver agreement was moderate among all experienced examiners (kappa = 0.45-0.80). The inexperienced examiner showed fair or moderate interobserver agreement (kappa = 0.32-0.45). Our results indicate that endometrial blood flow mapping using transvaginal power Doppler sonography is acceptably reproducible. More experience was associated with better intraobserver and interobserver agreement.

The Application of Diffusion‐ and Perfusion‐Weighted Magnetic Resonance Imaging in the Diagnosis and Therapy of Acute Cerebral Infarction

Diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI) was applied for stroke diagnose in 120 acute (< 48 h) ischemic stroke patients. At hyperacute (< 6 h) stage, it is difficult to find out the infarction zone in conventional T1 or T2 image, but it is easy in DWI, apparent diffusion coefficient (ADC) map; when at 3–6-hour stage it is also easy in PWI, cerebral blood flow (CBF) map, cerebral blood volume (CBV) map, and mean transit time (MTT) map; at acute (6–48 h) stage, DWI or PWI is more sensitive than conventional T1 or T2 image too. Combining DWI with ADC, acute and chronic infarction can be distinguished. Besides, penumbra which should be developed in meaning was used as an indication or to evaluate the therapeutic efficacy. There were two cases (< 1.5 h) that broke the model of penumbra because abnormity was found in DWI but not that in PWI, finally they recovered without any sequela.

Hyperperfusion on perfusion computed tomography following revascularization for acute stroke

To describe the findings of hyperperfusion on perfusion computed tomography (CT) in four patients following revascularization for acute stroke. In 2002-2003, among a series of 6 patients presenting with an acute stroke and treated with intra-arterial thrombolysis, we observed the presence of hyperperfusion in 3 patients on the follow-up CT perfusion. We included an additional patient who was treated with intravenous thrombolysis and who had hyperperfusion on the follow-up CT perfusion. We retrospectively analyzed their CT perfusion maps. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were compared between the affected territory and the normal contralateral hemisphere. In the four patients, the mean CBV and CBF were 3.6 +/- 2.0 ml/100 g and 39 +/- 25 ml/100 g/min in the affected territory compared to the normal side (mean CBV = 2.7 +/- 2.1 ml/100 g, mean CBF = 27 +/- 23 ml/100 g/min). There was no intracranial hemorrhage in the hyperperfused territories. At follow-up CT, some hyperperfused brain areas progressed to infarction, while others retained normal white to gray matter differentiation. CT perfusion can demonstrate hyperperfusion, which can be seen in an ischemic brain territory following recanalization.

Comparison of contrast agents with high molarity and with weak protein binding in cerebral perfusion imaging at 3 T

To examine and compare properties of high-molarity contrast agent gadobutrol (Gadovist) and weakly protein-binding agent gadobenate-dimeglumine (MultiHance in dynamic susceptibility contrast (DSC) perfusion imaging at 3 T. Sixteen healthy volunteers underwent three separate examinations with contrast agent doses of 0.1 and 0.2 mmol/kg body weight (bw) gadobutrol and 0.1 mmol/kg bw gadobenate-dimeglumine. Maps of relative regional cerebral blood volume (rCBV) and blood flow (rCBF) were calculated using deconvolution based on singular value decomposition. Signal and concentration time curves, the concentration-to-noise ratio (SNR(c)), and gray matter (GM)-to-white matter (WM) rCBV and rCBF contrast and ratios were evaluated in a region of interest (ROI)-based analysis. Image quality of calculated parametric maps was assessed in direct visual comparison and with respect to suitability for diagnostic purposes. The contrast agents displayed very similar results in the 0.1 mmol/kg examinations, both with respect to the quantitative evaluation parameters and in the qualitative assessment of the calculated parametric maps. Maps from 0.2 mmol/kg examinations were rated as being superior in quality, but with respect to diagnostic suitability all contrast agents and doses yielded images of sufficient quality. At 3 T, a gadobutrol or gadobenate-dimeglumine dose of 0.1 mmol/kg is sufficient for DSC magnetic resonance imaging (MRI) perfusion assessment. At the used small injection volumes, the tissue concentration curve was determined only by the gadolinium (Gd) dosage in mmol/kg, and the T2* relaxation effects of the two agents can be considered to be nearly identical in the applied gradient-echo (GRE) sequence.

Continuous arterial spin labeling perfusion measurements using single shot 3D GRASE at 3 T

Single shot 3D GRASE is less sensitive to field inhomogeneity and susceptibility effects than gradient echo based fast imaging sequences while preserving the acquisition speed. In this study, a continuous arterial spin labeling (CASL) pulse was added prior to the single shot 3D GRASE readout and quantitative perfusion measurements were carried out at 3 T, at rest and during functional activation. The sequence performance was evaluated by comparison with a CASL sequence with EPI readout. It is shown that perfusion measurements using CASL GRASE can be performed safely on humans at 3 T without exceeding the current RF power deposition limits. The maps of resting cerebral blood flow generated from the GRASE images are comparable to those obtained with the 2D EPI readout, albeit with better coverage in the orbitofrontal cortex. The sequence proved effective for functional imaging, yielding time series of images with improved temporal SNR with respect to EPI and group activation maps with increased significance levels. The method was further improved using parallel imaging techniques to provide increased spatial resolution and better separation of the gray-white matter cerebral blood flow maps.

Quantification of renal perfusion and function on a voxel‐by‐voxel basis: A feasibility study

The feasibility of a voxel-by-voxel deconvolution analysis of T(1)-weighted DCE data in the human kidney and its potential for obtaining quantification of perfusion and filtration was investigated. Measurements were performed on 14 normal humans and 1 transplant at 1.5 T using a Turboflash sequence. Signal time-courses were converted to tracer concentrations and deconvolved with an aorta AIF. Parametric maps of relative renal blood flow (rRBF), relative renal volume of distribution (rRVD), relative mean transit time (rMTT), and whole cortex extraction fraction (E) were obtained from the impulse response functions. For the normals average cortical rRBF, rRVD, rMTT, and E were 1.6 mL/min/mL (SD 0.8), 0.4 mL/mL (SD 0.1), 17s (SD 7), and 22.6% (SD 6.1), respectively. A gradual voxelwise rRBF increase is found from the center of two infarction zones toward the edges. Voxel IRFs showed more detail on the nefron substructure than ROI IRFs. In conclusion, quantitative voxelwise perfusion mapping based on deconvolved T(1)-DCE renal data is feasible, but absolute quantification requires inflow correction. rRBF maps and quantitative values are sufficiently sensitive to detect perfusion abnormality in pathologic areas, but further research is necessary to separate perfusion from extraction and to characterize the different compartments of the nephron on the (sub)voxel level.

The Diffusion-Weighted Lesion in Acute Stroke: Heterogeneous Patterns of Flow/Metabolism Uncoupling as Assessed by Quantitative Positron Emission Tomography

Background: To investigate what the hyperintense lesion in diffusion-weighted imaging (DWI) of acute ischaemic stroke represents metabolically, we prospectively imaged acute carotid-territory stroke patients with DWI along with fully quantitative positron emission tomography (PET), which gives physiological maps of cerebral blood flow (CBF), the cerebral metabolic rate of oxygen (CMRO₂) and the oxygen extraction fraction (OEF). Method: Of 10 patients who consented, 5 (3 males, 2 females, 53–84 years, NIHSS 6–16) completed the imaging protocol of back-to-back DWI and PET within 21 (mean 15.7, range 7–21) h of stroke onset. All images were co-registered with the DWI lesion forming a region of interest (ROI) that was transferred to the PET parametric maps (OEF, CBF, CMRO₂). Patterns of blood flow and metabolism were assessed within the DWI ROI. Results: Within the DWI lesions, the following patterns were observed: very low CBF and CMRO₂/variable OEF; low CBF/high OEF, and high CBF/low OEF. There was a heterogeneity of patterns between and within DWI lesions. In addition, areas of hyperperfusion (with low OEF) and areas of hypoperfusion (with high OEF) were seen outside the DWI lesions. Conclusion: The DWI lesion does not have a single flow/metabolism counterpart, suggesting that it reflects various stages of the ischaemic process.

Placental blood flow mapping in the first trimester of human pregnancy

Human placental circulation in the first trimester of pregnancy remains a subject of scientific debate. Most of the acquired knowledge on the physiological background of maternal-fetal interface relies on old studies, most of them performed in non-hemochorial placentas and using light and electron microscopy for the pathological specimens' evaluation. Recently, some ultrasonographic research in this field, using pulsed-wave and/or colour Doppler, yielded contradictory results. The availability of these non-invasive methods should allow the in vivo investigation of placental circulation since early phases of human pregnancy. A more recent technique – Power Doppler – should be preferred considering its resolution, angle-independence, higher sensitivity for lower velocities and absence of known harmful bioeffects in the early periods of gestation. We provide an overview on first trimester maternal-fetal circulation, assessed by non-invasive techniques, namely by transvaginal power Doppler ultrasonography, tr...

Placental blood flow mapping in the first trimester of human pregnancy

Placental blood flow mapping in the first trimester of human pregnancy

Myocardial blood flow mapping in mice using high‐resolution spin labeling magnetic resonance imaging: Influence of ketamine/xylazine and isoflurane anesthesia

Genetically modified mouse models of many human diseases reflecting cardiovascular alterations are currently available. To date, little information on absolute myocardial perfusion in mice is found in the literature. High-resolution quantitative myocardial blood flow maps (in-plane resolution 156 x 312 mum(2), slice thickness 1.5 mm) have been obtained noninvasively within 25 min at 4.7 T in 30 freely breathing C57/Bl6J mice using electrocardiogram- and respiration-gated spin labeling magnetic resonance imaging (MRI). Regional myocardial blood flow measurements were carried out, and the effects of isoflurane at two different concentrations and ketamine/xylazine anesthesia were assessed. The mean blood flow value in the left ventricular myocardium was 6.0 +/- 1.9 mL g(-1) min(-1) under ketamine/xylazine and 6.9 +/- 1.7 mL g(-1) min(-1) (group average +/- SD) under isoflurane (1.25%). Under the influence of higher isoflurane concentration (2.00%), myocardial blood flow increased dramatically to 16.9 +/- 1.8 mL g(-1)min(-1) with no significant change in heart rate. This work illustrates the feasibility of noninvasive quantitative myocardial perfusion mapping in mice using MRI. The study of the influence of anesthesia shows that myocardial blood flow is highly sensitive to isoflurane concentration. The method employed offers a noninvasive approach to longitudinal studies of murine models of cardiac disease.

Interaction between LSD and dopamine D2/3 binding sites in pig brain

The psychoactive properties of the hallucinogen LSD have frequently been attributed to high affinity interactions with serotonin 5HT2 receptors in brain. Possible effects of LSD on dopamine D2/3 receptor availability have not previously been investigated in living brain. Therefore, we used PET to map the binding potential (pB) of [11C]raclopride in brain of three pigs, first in a baseline condition, and again at 1 and 4 h after administration of LSD (2.5 microg/kg, i.v.). There was a progressive treatment effect in striatum, where the pB was significantly reduced by 19% at 4 h after LSD administration. Concomitant maps of cerebral blood flow did not reveal significant changes in perfusion during this interval. Subsequent in vitro studies showed that LSD displaced [3H]raclopride (2 nM) from pig brain cryostat sections with an IC50 of 275 nM according to a one-site model. Fitting of a two-site model to the data suggested the presence of a component of the displacement curves with a subnanomolar IC50, comprising 20% of the total [3H]raclopride binding. In microdialysis experiments, LSD at similar and higher doses did not evoke changes in the interstitial concentration of dopamine or its acidic metabolites in rat striatum. Together, these results are consistent with a direct interaction between LSD and a portion of dopamine D2/3 receptors in pig brain, possibly contributing to the psychopharmacology of LSD.

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Spiral phase velocity mapping of left and right coronary artery blood flow: Correction for through‐plane motion using selective fat‐only excitation

To develop a method of correcting both right and left coronary artery flow velocities for the through-plane motion of the vessel, in order to allow details in the temporal flow profiles to be viewed. The methods developed use selective excitation and velocity mapping of the epicardial fat surrounding the artery, either in a separate acquisition (temporal resolution = 22 msec) or interleaved with the water-excitation acquisition (temporal resolution = 44 msec) used to determine coronary blood flow velocities. The two methods were compared in 10 right and 13 left coronary arteries in healthy volunteers. For the right coronary arteries, correction for through-plane motion significantly reduces the mean systolic flow velocity (75.3 mm/second vs. 90.0 mm/second, P < 0.01), while the mean diastolic flow velocity is unchanged (96.8 mm/second vs. 94.5 mm/second, P = ns). The resulting profiles are biphasic, with approximately equal flow in systole and diastole. For the left arteries, correction for through-plane motion reduces the mean systolic flow velocity (25.0 mm/second vs. 72.8 mm/second, P < 0.001), resulting in the expected diastolic predominant flow profiles. For the right arteries, there were no significant differences in the mean systolic and mean diastolic velocities after correction with the separate fat-excitation acquisition, and after correction the poorer temporal resolution combined water excitation/fat excitation acquisition. However, for the left coronary arteries, the combined water excitation/fat excitation acquisition resulted in a slight reduction in the mean diastolic velocity (121.5 mm/second vs. 130.9 mm/second, P < 0.05). Selective excitation of the surrounding epicardial fat enables through-plane correction of both left and right coronary flow velocities, enabling the temporal details of flow velocity to be viewed. With a combined WE/FE acquisition, this can be performed without extending the study duration; however, the reduced temporal resolution and temporal mismatch of the excitations results in a blunting of rapidly changing flow profiles. As such, it may be less suitable for the left coronary artery, which has a greater range of through-plane motion than the right, and correction using separate WE and FE acquisitions, or the adjacent myocardium, may be preferable.