Conventional Magnetic Resonance Angiography Research Articles

Application of 3D-PCASL combined with t-ASL and MRA in the diagnosis of patients with isolated vertigo induced by posterior circulation ischemia

ObjectivesIsolated vertigo induced by posterior circulation ischemia (PCIV) can further progress into posterior circulation infarction. This study aimed to explore the diagnostic values of three-dimensional pseudo-continuous arterial spin labeling (3D-PCASL) combined with territorial arterial spin labeling (t-ASL) and magnetic resonance angiography (MRA) in visualizing and evaluating PCIV, seeking improved diagnostic tools for clinical guidance. Methods28 PCIVs (11 males, 17 females, aged from 55 to 83 years, mean age: 69.68 ± 9.01 years) and 28 healthy controls (HCs, 12 male, 16 female, aged from 56 to 87 years, mean age: 66.75 ± 9.86 years) underwent conventional magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), MRA, 3D-PCASL, and t-ASL. We compared the incidence of anatomic variants of the posterior circle of Willis in MRA, cerebral blood flow (CBF) and anterior collateral blood flow on postprocessing maps obtained from 3D-PCASL and t-ASL sequence between PCIVs and HCs. Chi-square test and paired t-test were analyzed statistically with SPSS 24.0 software. Results7 PCIVs (7/28, 25%) and 6 HCs (6/28, 21%) showed fetal posterior cerebral artery (FPCA) on MRA, including 1 HC, and 6 PCIVs with FPCA appeared hypoperfusion. 18 PCIVs (64%) and 2 HCs (7%) showed hypoperfusion in the posterior circulation (PC), including 1 HC and 7 PCIVs displayed anterior circulation collateral flow. Chi-square analyses demonstrated a difference in PC hypoperfusion between PCIVs and HCs, whether in the whole or FPCA-positive group assessment (P < 0.05). Paired t-test showed that the CBF values were significant difference for the bilateral PC asymmetrical perfusion in the PCIVs (P < 0.01). When compared to the bilateral PC symmetrical non-hypoperfusion area in the PCIVs and HCs, the CBF values were not significant (P > 0.05). The CBF values of the PC in PCIVs were lower than in HCs (P < 0.05). The reduction rate in the hypoperfusion side of the bilateral PC asymmetrical perfusion of the PCIVs ranged from 4% to 37%, while the HCs reduction rate was 7.7%. The average PC symmetrical perfusion average reduction rate of the PCIVs was 52.25%, while the HCs reduction rate was 42.75%. Conclusion3D-PCASL is a non-invasive and susceptible method for detecting hypoperfusion in PC, serving as a potential biomarker of PCIV. The suspected hypoperfusion in PC may be attributed to the emergence of FPCA and the manifestation of anterior collateral flow when combining t-ASL and MRA sequences. These findings demonstrated that 3D-PCASL combined with t-ASL and MRA sequences are the potential method to identify PCIV, leading to early diagnosis of PCIV and reducing the risk of progressing into infarction.

Optimizing High-Resolution MR Angiography: The Synergistic Effects of 3D Wheel Sampling and Deep Learning-Based Reconstruction.

The aim of this study was to assess the utility of the combined use of 3D wheel sampling and deep learning-based reconstruction (DLR) for intracranial high-resolution (HR)-time-of-flight (TOF)-magnetic resonance angiography (MRA) at 3 T. This prospective study enrolled 20 patients who underwent head MRI at 3 T, including TOF-MRA. We used 3D wheel sampling called "fast 3D" and DLR for HR-TOF-MRA (spatial resolution, 0.39 × 0.59 × 0.5 mm3) in addition to conventional MRA (spatial resolution, 0.39 × 0.89 × 1 mm3). We compared contrast and contrast-to-noise ratio between the blood vessels (basilar artery and anterior cerebral artery) and brain parenchyma, full width at half maximum in the P3 segment of the posterior cerebral artery among 3 protocols. Two board-certified radiologists evaluated noise, contrast, sharpness, artifact, and overall image quality of 3 protocols. The contrast and contrast-to-noise ratio of fast 3D-HR-MRA with DLR are comparable or higher than those of conventional MRA and fast 3D-HR-MRA without DLR. The full width at half maximum was significantly lower in fast 3D-MRA with and without DLR than in conventional MRA (P = 0.006, P < 0.001). In qualitative evaluation, fast 3D-MRA with DLR had significantly higher sharpness and overall image quality than conventional MRA and fast 3D-MRA without DLR (sharpness: P = 0.021, P = 0.001; overall image quality: P = 0.029, P < 0.001). The combination of 3D wheel sampling and DLR can improve visualization of arteries in intracranial TOF-MRA.

Diagnosis of Unruptured Intracranial Aneurysms Using Proton-Density Magnetic Resonance Angiography: A Comparison With High-Resolution Time-of-Flight Magnetic Resonance Angiography.

Differentiating intracranial aneurysms from normal variants using CT angiography (CTA) or MR angiography (MRA) poses significant challenges. This study aimed to evaluate the efficacy of proton-density MRA (PD-MRA) compared to high-resolution time-of-flight MRA (HR-MRA) in diagnosing aneurysms among patients with indeterminate findings on conventional CTA or MRA. In this retrospective analysis, we included patients who underwent both PD-MRA and HR-MRA from August 2020 to July 2022 to assess lesions deemed indeterminate on prior conventional CTA or MRA examinations. Three experienced neuroradiologists independently reviewed the lesions using HR-MRA and PD-MRA with reconstructed voxel sizes of 0.253 mm3 or 0.23 mm3, respectively. A neurointerventionist established the gold standard with digital subtraction angiography. We compared the performance of HR-MRA, PD-MRA (0.253-mm3 voxel), and PD-MRA (0.23-mm3 voxel) in diagnosing aneurysms, both per lesion and per patient. The Fleiss kappa statistic was used to calculate inter-reader agreement. The study involved 109 patients (average age 57.4 ± 11.0 years; male:female ratio, 11:98) with 141 indeterminate lesions. Of these, 78 lesions (55.3%) in 69 patients were confirmed as aneurysms by the reference standard. PD-MRA (0.253-mm3 voxel) exhibited significantly higher per-lesion diagnostic performance compared to HR-MRA across all three readers: sensitivity ranged from 87.2%-91.0% versus 66.7%-70.5%; specificity from 93.7%-96.8% versus 58.7%-68.3%; and accuracy from 90.8%-92.9% versus 63.8%-69.5% (P ≤ 0.003). Furthermore, PD-MRA (0.253-mm3 voxel) demonstrated significantly superior per-patient specificity and accuracy compared to HR-MRA across all evaluators (P ≤ 0.013). The diagnostic accuracy of PD-MRA (0.23-mm3 voxel) surpassed that of HR-MRA and was comparable to PD-MRA (0.253-mm3 voxel). The kappa values for inter-reader agreements were significantly higher in PD-MRA (0.820-0.938) than in HR-MRA (0.447-0.510). PD-MRA outperformed HR-MRA in diagnostic accuracy and demonstrated almost perfect inter-reader consistency in identifying intracranial aneurysms among patients with lesions initially indeterminate on CTA or MRA.

Imaging investigation of cervicocranial artery dissection by using high resolution magnetic resonance VWI and MRA: qualitative and quantitative analysis at different stages

BackgroundTo explore the value of magnetic resonance angiography (MRA) and high resolution magnetic resonance vessel wall imaging (HRMR-VWI) in cervicocranial artery dissection (CCAD) for the disease diagnosis, course staging and treatment. On the basis of qualitative evaluation, this study also extract the changes of different stages in vessel wall in different vessel segments to identify imaging indicators for the quantitative evaluation of CCAD.MethodsWe retrospectively enrolled 34 patients with CCAD (38branches) with conventional MRA and HRMR-VWI examinations. Two radiologists independently analyzed imaging features of vessel wall and lumen in the different stages, and the typical sign detection of artery dissection were compared between MRA and HRMR-VWI. Then the parameters of vessel wall was quantitatively evaluated by the post-processing software (Vesselmass, Leiden University Medical Center, Leiden, The Netherlands.ResultsHRMR-VWI revealed typical sign detection of artery dissection in all patients in the acute and subacute stage. Among them, the intimal flap/double lumen sign ditection were more common than the MRA, there was significant difference (P = 0.012). MRA revealed typical sign detection of artery dissection in more than half the patients, and the detection was no significant difference at the chronic stage between MRA and HRMR-VWI (P = 1.000/1.000/0.761). In the acute and subacute stage, the typical sign detection of intramural hematoma and Grade II enhancement revealed by HR-MRI was higher than the observations in the chronic stage (P = 0.000/0.000/0.016), while there was no significant difference by MRA (P = 0.902). The values of wall thickness, relative signal intensity of vessel wall enhancement, relative signal intensity of intramural hematoma (IMH), and percentage of stenosis in CCAD decreased from acute to subacute and then to chronic stages. Each quantitative parameter in patients with CCAD in the early stages (i.e., acute and subacute stages) was significantly different from that in patients with CCAD in the recovered group at chronic stage (P < 0.05). Wall thickness and relative signal intensity of vessel wall enhancement in patients with CCAD in the early stages were not significantly different from those in patients with CCAD in the incompletely recovered group at chronic stage (P > 0.05).ConclusionsAs the only noninvasive imaging technology, HRMR-VWI displays the structure of the vessel wall in vivo, showing not only excellent performance in the early diagnosis of CCAD, but also describing the changes of different stages in the qualitative and quantitative characteristics of vessel wall. It also helps to guide the diseasediagnosis, course staging and treatment of CCAD. Although the diagnostic efficacy of MRA was not as good as HRMR-VWI, it should be the first choice of method for routine examination in evaluating CCAD, especially at the chronic stage of CCAD.

Contrast-enhanced MR Angiography without Gadolinium-based Contrast Material: Clinical Applications Using Ferumoxytol

Vascular imaging can be challenging because of the wide variability of contrast dynamics in different vascular territories and potential safety concerns in patients with renal insufficiency or allergies. Off-label diagnostic use of ferumoxytol, a superparamagnetic iron nanoparticle approved for therapy, is a promising alternative to gadolinium-based contrast agents for MR angiography (MRA). Ferumoxytol has exhibited a reassuring safety profile when used within the dose range recommended for diagnostic imaging. Because of its prolonged and stable intravascular residence, ferumoxytol can be used in its steady-state distribution for a wide variety of imaging indications, including some where conventional MRA is unreliable. In this article, authors discuss some of the major vascular applications of ferumoxytol and highlight how it may be used to provide highly diagnostic images and improve the quality, workflow, and reliability of vascular imaging. Keywords: MR Angiography, MRI Contrast Agent, Cardiac, Vascular © RSNA, 2022

Minimizing table time in patients with claustrophobia using focused ferumoxytol-enhanced MR angiography (f-FEMRA): a feasibility study.

To assess the feasibility of a rapid, focused ferumoxytol-enhanced MR angiography (f-FEMRA) protocol in patients with claustrophobia. In this retrospective study, 13 patients with claustrophobia expressed reluctance to undergo conventional MR angiography, but agreed to a trial of up to 10 min in the scanner bore and underwent f-FEMRA. Thirteen matched control patients who underwent gadolinium-enhanced MR angiography (GEMRA) were identified for comparison of diagnostic image quality. For f-FEMRA, the time from localizer image acquisition to completion of the angiographic acquisition was measured. Two radiologists independently scored images on both f-FEMRA and GEMRA for arterial and venous image quality, motion artefact and diagnostic confidence using a 5-point scale, five being best. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the aorta and IVC were measured. The Wilcoxon rank-sum test, one-way ANOVA with Tukey correction and two-tailed t tests were utilized for statistical analyses. All scans were diagnostic and assessed with high confidence (scores ≥ 4). Average scan time for f-FEMRA was 6.27 min (range 3.56 to 10.12 min), with no significant difference between f-FEMRA and GEMRA in diagnostic confidence (4.86 ± 0.24 vs 4.69 ± 0.25, p = 0.13), arterial image quality (4.62 ± 0.57 vs 4.65 ± 0.49, p = 0.78) and motion artefact score (4.58 ± 0.49 vs 4.58 ± 0.28, p > 0.99). f-FEMRA scored significantly better for venous image quality than GEMRA (4.62 ± 0.42 vs 4.19 ± 0.56, p = 0.04). CNR in the IVC was significantly higher for steady-state f-FEMRA than GEMRA regardless of the enhancement phase (p < 0.05). Comprehensive vascular MR imaging of the thorax, abdomen and pelvis can be completed in as little as 5 min within the magnet bore using f-FEMRA, facilitating acceptance by patients with claustrophobia and streamlining workflow. A focused approach to vascular imaging with ferumoxytol can be performed in patients with claustrophobia, limiting time in the magnet bore to 10 min or less, while acquiring fully diagnostic images of the thorax, abdomen and pelvis.

Contrast-enhanced body magnetic resonance angiography: how we do it.

This review introduces the basic principles of contrast-enhanced magnetic resonance (MR) angiography and details four contrast-enhanced MR angiography sequences for body imaging with extracellular gadolinium-based contrast agents in pediatric patients. Specifically, this review covers (1) respiratory-navigated, cardiac-gated MR angiography; (2) time-resolved MR angiography; (3) conventional MR angiography; and (4) modified spoiled gradient echo variants. We present and discuss indications, technical considerations, sequence optimization, advantages and disadvantages, along with practical tips and illustrative case examples for each sequence.

Giant Cell Arteritis

Giant cell arteritis (GCA), also referred to as temporal arteritis, is a variant of large-vessel vasculitis. GCA should be considered in the differential diagnosis in patients aged >50 years, who present with headache, abrupt onset of visual disturbances, unexplained fever, a high erythrocyte sedimentation rate, and high serum C-reactive protein levels. Diagnosis of GCA is based on accurate interpretation of laboratory data, temporal artery biopsy findings, and imaging study results. Imaging modalities used for GCA include positron emission tomography, computed tomography (CT), CT angiography, and conventional magnetic resonance angiography. Biopsy is the gold standard for diagnosis of GCA. Glucocorticoids (GCs) are used as standard treatment to induce remission and also for maintenance therapy. However, clinicians should be aware of the adverse effects of GC treatment, including hyperglycemia, an immunocompromised state, and delirium. If adverse effects outweigh the benefits of GC treatment, it is necessary to consider switching to or adding an immunosuppressant to the therapeutic regimen.

Pencil Beam Presaturation Magnetic Resonance Imaging Helps to Identify Patients at Risk for Intolerance to Temporary Internal Carotid Artery Occlusion During Carotid Endarterectomy and Carotid Artery Stenting

There has been no effective method to predict ischemic intolerance to temporary internal carotid artery (ICA) occlusion during carotid artery reconstruction. Pencil beam presaturation (BeamSAT) pulse suppresses the flow signal of the target vessel in magnetic resonance angiography (MRA). Applying this method, we constructed ICA-selective MRA images. The aim of this study was to identify patients at risk for ischemic intolerance by ICA-selective MRA. By evaluating flow of anterior communicating artery (Acom) and A1 portion of anterior cerebral artery with ICA-selective MRA and posterior communicating artery (Pcom) with conventional MRA, we investigated associations of these collateral flow patterns with ischemic intolerance and decrease of regional cerebral oxygen saturation. The study included 58 patients who underwent carotid endarterectomy or carotid artery stenting. Six of 7 patients without Acom flow and Pcom flow demonstrated ischemic intolerance, whereas all patients (n= 51) with Acom and/or Pcom flow demonstrated tolerance. The accuracy of this prediction model according to Acom and Pcom flow patterns for ischemic intolerance was 0.98 (P=0.01, binomial test). Regional cerebral oxygen saturation decrease after ICA occlusion was significantly larger in patients without Acom flow and Pcom flow (12.0%± 6.0%) than in patients with Acom flow and Pcom flow (3.0% ± 3.1%, P < 0.01) and in patients with Acom flow but no Pcom flow (2.4% ± 5.2%, P < 0.01). These findings support the importance of Acom flow as a collateral route. ICA-selective MRA enables prediction of ischemic intolerance to temporary ICA occlusion during carotid endarterectomy or carotid artery stenting. This method provides valuable information regarding probability of an ischemic complication.

Clinical feasibility study of 3D intracranial magnetic resonance angiography using compressed sensing.

Compressed sensing (CS) has been widely used to improve the speed of MRI, but the feasibility of application in 3D intracranial MR angiography (MRA) needs to be evaluated in clinical practice. To evaluate the clinical feasibility of CS-MRA in comparison with conventional 3D-MRA (Con-MRA). Retrospective. Forty-nine consecutive patients with suspected intracranial arterial disease. 3T MRI. 3D time-of-flight (TOF) MRA using a CS algorithm and conventional 3D TOF MRA scan. Three radiologists (4, 11, and 12 years of experience in neuroradiology) independently assessed the image quality, vascular lesions, and variations of intracranial arteries of both CS-MRA and Con-MRA, respectively. The Kendall W test was performed to assess the interobserver agreement of image quality and intracranial arterial stenosis. A nonparametric test (Wilcoxon test) was used for comparison of the image quality and definition of the external carotid artery (ECA). Weighted kappa analysis was performed for the interstudy agreement of intracranial arterial stenosis. The aneurysm, decreased branches, congenital hypoplasia, absence, and variant branching of intracranial arteries were observed and evaluated for interobserver agreement and interstudy agreement by kappa analysis. Paired-t-tests for signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were conducted. Image quality is better for CS-MRA compared with Con-MRA with significance (Z = -3.710 to -2.673, with P < 0.01). The interstudy agreement of lesion and variation of intracranial arteries assessment for each observer was excellent. The SNR and CNR were significantly higher in CS-MRA compared with Con-MRA (P < 0.001). The definition of ECA of CS-MRA was significantly better (Z = -4.9, P < 0.001). CS-MRA showed significantly higher image quality with less blur, comparable image diagnostic performance of intracranial arteries, and better display of ECA than Con-MRA. 3 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:1843-1851.

Accelerated Time-of-Flight Magnetic Resonance Angiography with Sparse Undersampling and Iterative Reconstruction for the Evaluation of Intracranial Arteries

ObjectiveTo compare the image quality of three-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) with sparse undersampling and iterative reconstruction (sparse TOF) with that of conventional TOF MRA.Materials and MethodsThis study included 56 patients who had undergone sparse TOF MRA for intracranial artery evaluation on a 3T MR scanner. Conventional TOF MRA scans were also acquired from 29 patients with matched acquisition times and another 27 patients with matched scanning parameters. The image quality was scored using a five-point scale based on the delineation of arterial vessel segments, artifacts, overall vessel visualization, and overall image quality by two radiologists independently, and the data were analyzed using the non-parametric Wilcoxon signed-rank test. Contrast ratios (CRs) of vessels were compared using the paired t test. Interobserver agreement was calculated using the kappa test.ResultsCompared with conventional TOF at the same spatial resolution, sparse TOF with an acceleration factor of 3.5 could reduce acquisition time by 40% and showed comparable image quality. In addition, when compared with conventional TOF with the same acquisition time, sparse TOF with an acceleration factor of 5 could also achieve higher spatial resolution, better delineation of vessel segments, fewer artifacts, higher image quality, and a higher CR (p < 0.05). Good-to-excellent interobserver agreement (κ: 0.65–1.00) was obtained between the two radiologists.ConclusionCompared with conventional TOF, sparse TOF can achieve equivalent image quality in a reduced duration. Furthermore, using the same acquisition time, sparse TOF could improve the delineation of vessels and decrease image artifacts.

Detecting lenticulostriate artery lesions in patients with acute ischemic stroke using high-resolution MRA at 7 T.

Recent advances in high-resolution (HR) magnetic resonance angiography (MRA) using ultrahigh-field systems enable direct visualization of the lenticulostriate arteries (LSAs), which had been hardly achieved by conventional MRA. Hence, by using HR-MRA at 7 T, we attempted to assess occlusive changes in the LSAs in patients with LSA territorial infarcts. We prospectively examined 34 consecutive patients with acute ischemic stroke in the LSA territory using a 7 T scanner. We measured the lengths of the relevant LSAs on HR-MRA and the diameters/volume of the infarcts and compared these between the patients with/without occlusive changes in the LSAs. On HR-MRA, occlusion of the LSAs was observed in 19 (59%) of 32 patients who were eligible for the analyses. The curved/straight lengths of the LSAs in the patients with LSA occlusion (23.1-31.1/17.8-24.3 mm) were significantly shorter than in those without apparent LSA occlusion (25.8-39.5/24.0-30.4 mm) ( P = 0.027/0.003). The anteroposterior/superoinferior diameters of the infarcts were significantly larger in the occluded-LSA group (14.5-21.4/14.9-22.2 mm) than in the intact-LSA group (10.9-16.8/10.8-16.2 mm) ( P = 0.041/0.011). In addition, the curved lengths of the relevant LSAs showed significant correlations with the superoinferior diameters of the infarcts ( r = 0.38, P = 0.034). Occlusive changes in the LSAs were frequently found in patients with acute ischemic stroke within the LSA territory when using HR-MRA at 7 T and were substantially related to superoinferior extension of the infarcts.

Interstudy reproducibility of dark blood high-resolution MRI in evaluating basilar atherosclerotic plaque at 3 Tesla.

We aimed to evaluate the interscan, intraobserver, and interobserver reproducibility of basilar atherosclerotic plaque employing dark blood high-resolution magnetic resonance imaging (HR-MRI) at 3 Tesla. Sixteen patients (14 males and 2 females) with > 30% basilar stenosis as identified by conventional magnetic resonance angiography were prospectively recruited for scan and rescan examinations on a 3 Tesla MRI system using T2-weighted turbo spin-echo protocol. Two observers independently measured the areas of vessels and lumens. Wall area was derived by subtracting the lumen area from the vessel area. Areas of vessels, lumens and walls were compared for the evaluation of interscan variability of basilar plaque. To assess the intraobserver variability, one observer reevaluated all the images of the first scan after a 4-week interval. Fourteen patients were included in the final analysis. No clinically significant difference was observed for interscan, intraobserver, and interobserver measurements. The intraclass correlations for vessel, lumen, and wall areas were excellent and ranged from 0.973 to 0.981 for the interscan measurements, 0.997 to 0.998 for the intraobserver measurements and 0.979 to 0.985 for the interobserver measurements. The coefficients of variation for quantitative basilar morphology measurements were 4.31%-10.35% for the interscan measurements, 1.41%-4.62% for the intraobserver measurements and 3.79%-8.46% for the interobserver measurements. Compared with the interscan and interobserver measurements, narrow intervals of the scatterplots were observed for the intraobserver measurements by Bland-Altman plots. Basilar atherosclerotic plaque imaging demonstrates excellent reproducibility at 3 Tesla. The study proves that dark blood HR-MRI may serve as a reliable tool for clinical studies focused on the progression and treatment response of basilar atherosclerosis.

A local excitation magnetic resonance imaging method for intracranial unruptured aneurysm at the distal internal carotid artery

It is often difficult to diagnose an intracranial aneurysm at the distal internal carotid artery by conventional magnetic resonance imaging. PurposeWe assessed the effectiveness of the local excitation technique, a new application for magnetic resonance imaging, to clarify the geometric structure of aneurysm and adjacent branches at the distal internal carotid artery. Study designTwo independent evaluators diagnosed 10 cases of suspected aneurysms at the distal internal carotid artery by T2-weighted magnetic resonance imaging with application of local excitation, adding it to conventional time-of-flight–magnetic resonance angiography. FindingsWe successfully distinguished the aneurysm from infundibular dilatation in five of 10 cases. ConclusionOur results suggested that addition of local excitation to conventional magnetic resonance angiography was effective to diagnose unruptured aneurysm at the distal internal carotid artery, to clarify the configuration of the prominent lesion or whether the location of the adjacent branch orifice on the parent vessel was symmetric or asymmetric.

A case report of multiple cervical artery dissection after peripheral type facial palsy and use of steroids

BackgroundCervical artery dissection is one of the most important causes of ischemic stroke in young age patients. However, multiple cervical artery dissection simultaneously involving the anterior and posterior circulation is uncommon. Here, we would like to report a case of a patient with bilateral vertebral artery (VA) and internal carotid artery dissection (ICA) after a use of systemic steroid due to peripheral facial palsy.Case presentationA 44-year-old man with hypertension visited emergency department due to recurrent vertigo. He was receiving methyl prednisolone for two weeks for the treatment of right peripheral type facial palsy which occurred after retro-orbital headache. Neurologic examination revealed severe ataxia at left side. Sensory for pain and temperature was declined in the right arm and leg. Diffusion-weighted image showed an acute ischemic lesion at the whole territory of posterior-inferior cerebellar artery. Severe stenosis was observed from bilateral VAs and ICAs on conventional magnetic resonance angiography. Intramural hematoma and intimal flap was observed from the high-resolution MRI.ConclusionsPeripheral type facial palsy is an unusual presentation of carotid dissection. Steroids aggravate arterial dissection by increasing blood pressure and blood vessel fragility by its negative effect on connective tissue strength. Use of steroid in patients with peripheral type facial palsy with severe headache may need caution.

Non-contrast compressed sensing whole-heart coronary magnetic resonance angiography at 3T: A comparison with conventional imaging

ObjectivesWhole-heart coronary magnetic resonance angiography (MRA) is a promising non-contrast, radiation-free technique for assessing the coronary artery. Yet, a disadvantage of coronary MRA is the relatively long acquisition time. The purpose of this study was to evaluate the scan time and image quality of compressed sensing (CS) coronary MRA compared with conventional coronary MRA. Materials and methodsTwenty healthy volunteers underwent navigator-gated coronary MRA with a CS prototype sequence and conventional navigator-gated coronary MRA on a clinical 3T MRI scanner without contrast medium. The spatial resolutions were 1.33 × 1.33 × 1.20 mm3 for CS and 1.33 × 1.33 × 1.48 mm3 interpolated to 0.70 × 0.70 × 1.20 mm3 for conventional, respectively. We compared acquisition times, rated image quality on a 4-point scale (RCA; proximal, middle, and distal, LAD; main, proximal, middle, and distal, LCX; proximal and distal), and measured the visualized vessel lengths of three vessels. ResultsThe mean acceptance rates were 44.9% for CS coronary MRA and 48.7% for conventional coronary MRA (p = .39). The mean effective scan time was 3 min 45 s for CS coronary MRA and 15 min 6 s for conventional coronary MRA (p < 0.001). Image quality scores were significantly lower for CS coronary MRA than for conventional coronary MRA (3.4 ± 0.7 for CS vs. 3.8 ± 0.4 for conventional; p < 0.0001). Conventional coronary MRA images were scored >3.4 in all segments on average, while CS coronary MRA images were scored >3.2 (good quality for diagnosis) in almost all segments, with only the distal RCA segment graded 2.9 on average. The average visible vessel lengths for CS and conventional coronary MRA were as follows: 11.5 ± 4.4 cm and 12.5 ± 4.8 cm for the RCA, respectively (p < 0.05, 95% limits of agreement [LOA]; −3.6 to 1.6 cm); 10.6 ± 3.0 cm and 11.1 ± 2.9 cm for the LAD, respectively (p = .15, 95% LOA −4.0 to 2.8 cm); and 7.1 ± 2.2 cm and 8.2 ± 2.5 cm for the LCX, respectively (p < 0.05, 95% LOA −4.0 to 1.7 cm). ConclusionsNon-contrast coronary MRA using CS could largely shorten acquisition time, compared with conventional navigator-gated coronary MRA, while maintaining acceptable visualization at 3T.

Evaluation of vascular invasion in patients with musculoskeletal tumors of lower extremities: use of time-resolved 3D MR angiography at 3-T.

Background Time-resolved angiography with stochastic trajectories (TWIST) sequence makes considerable progress in temporal and spatial resolution, which presents high potential in evaluation of vascular diseases. Purpose To assess magnetic resonance imaging (MRI) using TWIST MR angiography (MRA) sequence in the assessment of vascular invasion for bone and soft-tissue tumors in comparison to computed tomography angiography (CTA) as the reference standard. Material and Methods Thirty-three patients with lower extremity musculoskeletal tumors were imaged with conventional MR and TWIST MRA. CTA was performed 48 h later. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the femoral artery were calculated. Vascular invasion as determined by MRA and CTA was separately analyzed. Vascular invasion by MRA and CTA were analyzed with kappa coefficients to determine agreement between the imaging methods. Results Seven cases of bone and 26 cases of soft tissue tumors were examined. SNR and CNR of the femoral artery were excellent for TWIST MRA (mean ± SD values of 317 ± 80 and 276 ± 76, respectively). Based on the TWIST sequence, the vessels were free of tumor in 16 cases. Vascular displacement was found in 11 cases and vascular stenosis in six cases. The MRA findings conflicted with CTA findings in only one case. The kappa value was 0.953 ( P < 0.01). In five cases, vascular malformations were found with TWIST MRA but not CTA. Conclusion TWIST MRA enables accurate delineation of anatomical structures and tumor arterial involvement, providing reliable preoperative imaging information with respect to lower extremity musculoskeletal tumors.

Simultaneous bright- and black-blood whole-heart MRI for noncontrast enhanced coronary lumen and thrombus visualization.

PurposeTo develop a 3D whole‐heart Bright‐blood and black‐blOOd phase SensiTive (BOOST) inversion recovery sequence for simultaneous noncontrast enhanced coronary lumen and thrombus/hemorrhage visualization.MethodsThe proposed sequence alternates the acquisition of two bright‐blood datasets preceded by different preparatory pulses to obtain variations in blood/myocardium contrast, which then are combined in a phase‐sensitive inversion recovery (PSIR)‐like reconstruction to obtain a third, coregistered, black‐blood dataset. The bright‐blood datasets are used for both visualization of the coronary lumen and motion estimation, whereas the complementary black‐blood dataset potentially allows for thrombus/hemorrhage visualization. Furthermore, integration with 2D image‐based navigation enables 100% scan efficiency and predictable scan times. The proposed sequence was compared to conventional coronary MR angiography (CMRA) and PSIR sequences in a standardized phantom and in healthy subjects. Feasibility for thrombus depiction was tested ex vivo.ResultsWith BOOST, the coronary lumen is visualized with significantly higher (P < 0.05) contrast‐to‐noise ratio and vessel sharpness when compared to conventional CMRA. Furthermore, BOOST showed effective blood signal suppression as well as feasibility for thrombus visualization ex vivo.ConclusionA new PSIR sequence for noncontrast enhanced simultaneous coronary lumen and thrombus/hemorrhage detection was developed. The sequence provided improved coronary lumen depiction and showed potential for thrombus visualization. Magn Reson Med 79:1460–1472, 2018. © 2017 International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Preprocedural MRI and MRA in planning fibroid embolization.

This pictorial review aims to discuss and illustrate the up-to-date use of preprocedural magnetic resonance imaging (MRI) in selecting patients and planning uterine artery embolization (UAE). The merits of magnetic resonance angiography (MRA) in demonstrating the pelvic vasculature to guide UAE are highlighted. MRI features of fibroids and their main differential diagnoses are presented. Fibroid characteristics, such as location, size, and enhancement, which may impact patient selection and outcome, are presented based on recent literature. Pelvic arterial anatomy relevant to UAE, including vascular variants are illustrated, with conventional angiography and MRA imaging correlation. MRA preprocedural determination of the optimal projection angles for uterine artery catheterization is straightforward and constitutes an important strategy to minimize ionizing radiation exposure during UAE. A reporting template for MRI/MRA preassessement of UAE for fibroid treatment is provided.

Abstract WP150: BeamSAT MRI Help to Identify Patients at Risk for Intolerance to Temporary Internal Carotid Artery Occlusion During CEA and CAS

Introduction: Pencil Beam type presaturation (BeamSAT) pulse on a major cervical vessel enables selective suppression of blood flow signal of the applied vessel in MR angiography (MRA). By subtracting the BeamSAT pulse-added MRA of an internal carotid artery (ICA) from conventional MRA, only the contralateral ICA image (SubBeamSAT image) can be obtained (Figure A, B). In this way, an ICA-selective MRA with more physiologial flow pattern can be obtained, because it requires no powerful injection of contrast medium. Purpose: The aim of this study was to investigate whether preoperative assessment of the flow of Acom/A1 by SubBeamSAT image and posterior communicating artery (Pcom) by conventional MRA could identify patients at risk for intolerance to intraoperative temporary ICA occlusion. Method: 29 patients who underwent carotid endarterectomy (CEA) (n = 17) or carotid artery stenting (CAS) (n = 12) were enrolled in the current study. All patients underwent the SubBeamSAT images and conventional MRA pre- and post-operatively. Response to ICA temporally occlusion was recorded during the revascularization procedure. Results: Among twenty-nine patients, 4 patients who demonstrate neither the Acom/A1 flow on SubBeamSAT image (Figure. B) nor Pcom flow on MRA showed intolerance. In contrast, the remaining 25 patients who demonstrated Acom/A1 (Figure. A) and/or Pcom flow showed tolerance. Intolerance to ICA occlusion was excellently predicted by visualization of collateral flow via Acom and Pcom (specificity: 100%, sensitivity: 100%, p=0.00004). Conclusions: SubBeamSAT image is useful for evaluating the flow of Acom from A1 portion of the healthy side to A2 portion of the contralateral side, which is often difficult to evaluate with conventional MRA. With the SubBeamSAT image, it is feasible to evaluate the Acom/A1 flow accurately. In conclusion, SubBeamSAT image enables excellent prediction for the intolerance to temporary ICA occlusion.