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Magnetic Resonance Angiography (magnetic + resonance_angiography)
Kinds of Magnetic Resonance Angiography Selected AbstractsThree-Dimensional Anatomy of the Left Atrium by Magnetic Resonance Angiography: Implications for Catheter Ablation for Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2006MOUSSA MANSOUR M.D. Background: Pulmonary vein isolation (PVI) has become one of the primary treatments for symptomatic drug-refractory atrial fibrillation (AF). During this procedure, delivery of ablation lesions to certain regions of the left atrium can be technically challenging. Among the most challenging regions are the ridges separating the left pulmonary veins (LPV) from the left atrial appendage (LAA), and the right middle pulmonary vein (RMPV) from the right superior (RSPV) and right inferior (RIPV) pulmonary veins. A detailed anatomical characterization of these regions has not been previously reported. Methods: Magnetic resonance angiography (MRA) was performed in patients prior to undergoing PVI. Fifty consecutive patients with a RMPV identified by MRA were included in this study. Ridges associated with the left pulmonary veins were examined in an additional 30 patients who did not have a RMPV. Endoluminal views were reconstructed from the gadolinium-enhanced, breath-hold three-dimensional MRA data sets. Measurements were performed using electronic calipers. Results: The width of the ridge separating the LPV from the LAA was found to be 3.7 ± 1.1 mm at its narrowest point. The segment of this ridge with a width of 5 mm or less was 16.6 ± 6.4 mm long. The width of the ridges separating the RMPV from the RSPV and the RIPV was found to be 3.0 ±1.5 mm and 3.1 ±1.8 mm, respectively. There were no significant differences between LPV ridges for patients with versus without a RMPV. Conclusion: The width of the ridges of atrial tissue separating LPV from the LAA and the RMPV from its neighboring veins may explain the technical challenge in obtaining stable catheter positions in these areas. A detailed assessment of the anatomy of these regions may improve the safety and efficacy of catheter ablation at these sites. [source] Characterization of a New Pulmonary Vein Variant Using Magnetic Resonance Angiography:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2004Imaging, Incidence, Interventional Implications of the "Right Top Pulmonary Vein" Introduction: Catheter ablation of the pulmonary veins (PVs) for prevention of recurrent atrial fibrillation requires precise anatomic information. We describe the characteristics of a new anatomic variant of PV anatomy using magnetic resonance angiography. Methods and Results: A 1.5-T magnetic resonance imaging system with a body coil or a torso phased-array coil was used before and after gadolinium injection. Magnetic resonance angiograms were acquired with a breath-hold three-dimensional fast spoiled gradient-echo imaging sequence in the coronal plane. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. A newly described variant PV ascending from the roof of the left atrium was found in 3 of 91 subjects. The mean ostial diameter of the roof PV was 7 ± 2 mm, the mean distance from the ostium to the first branching point was 22 ± 8.5 mm, and the mean distance to the right superior PV was 3.3 ± 0.6 mm. Conclusion: We refer to the newly described variant of PV anatomy as the "right top pulmonary vein." It is important to be aware of this anatomic pattern to avoid inadvertent catheter intubation, which can result in misleading mapping results and PV stenosis. (J Cardiovasc Electrophysiol, Vol. 15, pp. 538-543, May 2004) [source] Coronary Magnetic Resonance AngiographyJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 3 2003Richard E Slaughter No abstract is available for this article. [source] Comparison of Transcranial Color-Coded Sonography and Magnetic Resonance Angiography in Acute Ischemic StrokeJOURNAL OF NEUROIMAGING, Issue 4 2001Li-Ming Lien MD ABSTRACT Background and Purpose. This study was designed to assess the accuracy of transcranial color-coded sonography (TCCS) as compared to magnetic resonance angiography (MRA) for detecting intracranial arterial stenosis in patients with acute cerebral ischemia. Methods. The authors prospectively identified 120 consecutive patients admitted with acute ischemic stroke and performed both TCCS and MRA with a mean interval of 1 day. TCCS data (sampling depth, peak systolic and end diastolic angle-corrected velocity, mean angle-corrected velocity, and pulsatility index) for middle cerebral arteries (MCAs) were compared to MRA data and classified into 4 grades: normal (grade 1): normal caliber and signal; mild stenosis (grade 2): irregular lumen with reduced signal; severe stenosis (grade 3): absent signal in the stenotic segment (flow gap) and reconstituted distal signal; and possible occlusion (grade 4): absent signal. The cutoffs were chosen to maximize diagnostic accuracy. Results. Interobserver agreement for MRA grading resulted in a weighted-kappa value of 0.776. The rate of poor temporal window was 37% (89/240). Doppler signals were obtained in 135 vessels, and the angle-corrected velocities (peak systolic, end diastolic, mean) were significantly different (P= .001, P= .006, P < .001) among the MRA grades: grade 1 (100, 47, 68 cm/s), grade 2 (171, 72, 110 cm/s), grade 3 (226, 79, 134 cm/s), grade 4 (61, 26, 39 cm/s). Additionally, an angle-corrected MCA peak systolic velocity ,120 cm/s correlates with intracranial stenosis on MRA (grade 2 or worse) with high specificity (90.5%; 95% confidence interval = 78.5%,96.8%) and positive predictive value (93.9%) but relatively low sensitivity (66.7%; 95% confidence interval = 61.2%,69.5%) and negative predictive value (55.1%). Conclusion. Elevated MCA velocities on TCCS correlate with intracranial stenosis detected on MRA. An angle-corrected peak systolic velocity ,120 cm/s is highly specific for detecting intracranial stenosis as defined by significant MRA abnormality. [source] Acute Intracranial Hemorrhage in the Brain Caused by AcupunctureHEADACHE, Issue 5 2000Daniel Chung Ann Choo MD A 44-year-old Chinese man developed severe occipital headache, nausea, and vomiting during acupuncture treatment of the posterior neck for chronic neck pain. Computed tomography of the head showed hemorrhage in the fourth, third, and lateral ventricles. A lumbar puncture confirmed the presence of blood. Magnetic resonance angiography with gadolinium did not reveal any saccular aneurysms or arteriovenous malformations. The patient's headache resolved over a period of 28 days without any neurological deficits. Acupuncture of the posterior neck can cause acute intracranial hemorrhage. [source] Three-Dimensional Anatomy of the Left Atrium by Magnetic Resonance Angiography: Implications for Catheter Ablation for Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2006MOUSSA MANSOUR M.D. Background: Pulmonary vein isolation (PVI) has become one of the primary treatments for symptomatic drug-refractory atrial fibrillation (AF). During this procedure, delivery of ablation lesions to certain regions of the left atrium can be technically challenging. Among the most challenging regions are the ridges separating the left pulmonary veins (LPV) from the left atrial appendage (LAA), and the right middle pulmonary vein (RMPV) from the right superior (RSPV) and right inferior (RIPV) pulmonary veins. A detailed anatomical characterization of these regions has not been previously reported. Methods: Magnetic resonance angiography (MRA) was performed in patients prior to undergoing PVI. Fifty consecutive patients with a RMPV identified by MRA were included in this study. Ridges associated with the left pulmonary veins were examined in an additional 30 patients who did not have a RMPV. Endoluminal views were reconstructed from the gadolinium-enhanced, breath-hold three-dimensional MRA data sets. Measurements were performed using electronic calipers. Results: The width of the ridge separating the LPV from the LAA was found to be 3.7 ± 1.1 mm at its narrowest point. The segment of this ridge with a width of 5 mm or less was 16.6 ± 6.4 mm long. The width of the ridges separating the RMPV from the RSPV and the RIPV was found to be 3.0 ±1.5 mm and 3.1 ±1.8 mm, respectively. There were no significant differences between LPV ridges for patients with versus without a RMPV. Conclusion: The width of the ridges of atrial tissue separating LPV from the LAA and the RMPV from its neighboring veins may explain the technical challenge in obtaining stable catheter positions in these areas. A detailed assessment of the anatomy of these regions may improve the safety and efficacy of catheter ablation at these sites. [source] Topographic Patterns of Small Subcortical Infarcts Associated with MCA Stenosis: A Diffusion-Weighted MRI StudyJOURNAL OF NEUROIMAGING, Issue 3 2006Xin Wang MD ABSTRACT Background and Purpose. Small subcortical infarcts (SSI, maximum lesion diameter ,2.0 cm) are usually considered as infarcts caused by small vessel disease. However, SSI can also be associated with large artery occlusive disease such as middle cerebral artery (MCA) stenosis. We performed a prospective study to investigate the relationship between MCA stenosis and SSI distribution and further to investigate the mechanism of SSI caused by MCA stenosis. Methods. Magnetic resonance angiography (MRA) and diffusion-weighed MRI (DWI) of consecutive acute ischemic stroke patients with recent SSI were studied. The distribution of acute infarcts on DWI was categorized as cortical infarct (CI), border zone infarct (BI), or perforating artery infarct (PAI). Results. Totally, 93 cases were recruited, among which 12 had single SSI with MCA stenosis (group 1) and 26 patients had multiple SSI with MCA stenosis (group 2), while 55 patients without MCA stenosis had single SSI (group 3). For patients with single SSI and MCA stenosis, 6 had BI and 6 had PAI; for patients with multiple SSI and MCA stenosis, 25 had BI, 4 had PAI and 9 had CI (compared with group1: P= .001); for patients with single SSI but without MCA stenosis, 20 had BI and 35 had PAI (compared with group1: P= .58). Conclusion. Multiple acute infarcts along the border zone are the commonest pattern in small infarcts with MCA stenosis, especially among those with multiple acute infarcts. Our data suggest that hemodynamic compromise and artery-to-artery embolism may be both important factors for infarcts in patients with MCA stenosis. [source] Hemodynamic Effects of Innominate Artery Occlusive Disease on Anterior Cerebral ArteryJOURNAL OF NEUROIMAGING, Issue 1 2002Teng-Yeow Tan MD Stenoses of the innominate artery (IA) may affect flow conditions in the carotid arteries. However, alternating flow in ipsilateral anterior cerebral artery (ACA) due to IA stenosis is extremely rare. A 49-year-old woman who was evaluated for symptomatic cerebrovascular disease presented with right latent subclavian and right carotid system steal. Transcranial Doppler examination displayed systolic deceleration wave-forms in the right terminal internal carotid artery and alternating flow in the right ACA. Magnetic resonance angiography demonstrated tight stenosis of the right IA. For a thorough study of the hemodynamic effects of IA stenosis, a combination of duplex and transcranial Doppler examination is required. [source] High-resolution magnetic resonance angiography in the mouse using a nanoparticle blood-pool contrast agentMAGNETIC RESONANCE IN MEDICINE, Issue 6 2009Gabriel P. Howles Abstract High-resolution magnetic resonance angiography is already a useful tool for studying mouse models of human disease. Magnetic resonance angiography in the mouse is typically performed using time-of-flight contrast. In this work, a new long-circulating blood-pool contrast agent,a liposomal nanoparticle with surface-conjugated gadolinium (SC-Gd liposomes),was evaluated for use in mouse neurovascular magnetic resonance angiography. A total of 12 mice were imaged. Scan parameters were optimized for both time-of-flight and SC-Gd contrast. Compared to time-of-flight contrast, SC-Gd liposomes (0.08 mmol/kg) enabled improved small-vessel contrast-to-noise ratio, larger field of view, shorter scan time, and imaging of venous structures. For a limited field of view, time-of-flight and SC-Gd were not significantly different; however, SC-Gd provided better contrast-to-noise ratio when the field of view encompassed the whole brain (P < 0.001) or the whole neurovascular axis (P < 0.001). SC-Gd allowed acquisition of high-resolution magnetic resonance angiography (52 × 52 × 100 micrometer3 or 0.27 nL), with 123% higher (P < 0.001) contrast-to-noise ratio in comparable scan time (,45 min). Alternatively, SC-Gd liposomes could be used to acquire high-resolution magnetic resonance angiography (0.27 nL) with 32% higher contrast-to-noise ratio (P < 0.001) in 75% shorter scan time (12 min). Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Magnetic resonance angiography of collateral vessels in a murine femoral artery ligation modelNMR IN BIOMEDICINE, Issue 1 2004Shawn Wagner Abstract The in vivo detection of growing collateral vessels following arterial occlusion is difficult in small animals. We have addressed the feasibility of performing high resolution time-of-flight angiograms to monitor the growth of collateral vessels after femoral artery occlusion in mice. We will also present a low-pass quadrature birdcage coil construction with a sufficient signal-to-noise ratio to produce high resolution. After a 4-month recovery period a C57BL/6 mouse with a surgical occlusion of the right femoral artery was used to assess the image quality and time requirements to produce magnetic resonance angiograms sufficient to assess collateral artery development using a two-dimensional gradient echo sequence. At a resolution of 100,×,100,×,100,,m and a matrix size of 256,×,128,×,256 for a 2.56,cm isometric volume, three scans were performed with one, two and four repetitions resulting in signal-to-noise ratios for the femoral artery proximal to the ligation site of 58, 126 and 194, respectively. Five C57BL/6 mice were additionally measured 4 weeks after occlusion using two repetitions and the visual collateral vessels were assessed for number and location: 2.0,±,1.2 in quadriceps muscle, 0.6,±,0.5 in adductor (deep adductor vessel), 0.0,±,0.0 in adductor (surface adductor vessels). The results showed a significant difference, two-sided t -test, p,<,0.05, in number of vessels in all the locations. We have shown that this method can be utilized to elucidate the contribution of collateral vessels to arterial flow. Copyright © 2004 John Wiley & Sons, Ltd. [source] Therapy-resistant skin ulcers on hypoplastic leg associated with neurofibromatosis type 1THE JOURNAL OF DERMATOLOGY, Issue 2 2008Taku FUJIMURA ABSTRACT We describe a case of therapy-resistant skin ulcers in sporadic neurofibromatosis type 1. A 40-year-old woman had suffered from neurofibromata on her trunk and extremities since 30 years prior. She suffered from hypoplasia of her right leg from a young age and had a 1-year history of therapy-resistant skin ulcers on the leg and inguinal region. Magnetic resonance angiography disclosed a narrowed femoral artery at the level of the upper thigh with poor root in the inner side corresponding to the ulcerated lesions. The vascular changes were thought to be the cause of the skin ulcers. [source] Magnetic resonance angiography in reversible cerebral vasoconstriction syndromesANNALS OF NEUROLOGY, Issue 5 2010Shih-Pin Chen MD Objective To investigate the evolution and clinical significance of vasoconstriction on magnetic resonance angiography (MRA) in patients with reversible cerebral vasoconstriction syndromes (RCVS). Methods Patients with RCVS were recruited and followed up with MRA examinations until normalization of vasoconstriction or for 6 months. The vasoconstriction severity of the major cerebral arterial segments (M1, M2, A1, A2, P1, P2, and basilar artery) was scored on a 5-point scale: 0 (0,<10%), 1 (10,<25%), 2 (25,<50%), 3 (50,<75%), and 4 (,75%). Subjects with at least 1 segment with a vasoconstriction score ,2 were eligible for the study. Initial mean scores of single or combined arterial segments were used to predict ischemic complications. Results Seventy-seven patients with RCVS (8 men/69 women; average age 47.7 ± 11.6 years) finished the study with a total of 225 MRAs performed. The mean number of arterial segments involved was 5.3 ± 3.0 in the initial MRA. Vasoconstriction scores reached their maximum 16.3 ± 10.2 days after headache onset, close to the average timing of headache resolution (16.7 ± 8.6 days). Vasoconstriction evolved in a parallel trend among different arterial segments. Seven (9.1%) patients developed posterior reversible encephalopathy syndromes (PRES). Six (7.8%) patients had ischemic stroke. A logistic regression model demonstrated that the M1,P2 combined score was associated with highest risk of PRES (odds ratio [OR], 11.6, p = 0.005) and ischemic stroke (OR, 3.4; p = 0.026). Interpretation MRA evaluation in patients with RCVS is valid. Vasoconstriction was pervasive and outlasted headache resolution. Vasoconstrictions in M1 and P2 are important determinants for PRES and ischemic stroke. ANN NEUROL 2010;67:648,656 [source] A new type of susceptibility-artefact-based magnetic resonance angiography: intra-arterial injection of superparamagnetic iron oxide particles (SPIO) A Resovist® in combination with TrueFisp imaging: a feasibility studyCONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2006Robbert M. Maes Abstract The goal of this study was to evaluate the use of super paramagnetic particles of iron oxide (SPIO) as a dark blood contrast agent, in combination with a bright blood steady-state free precession sequence for magnetic resonance angiography (MRA), in an animal model. The original concentration of the SPIO of 500,mmol Fe/l and dilutions to 250, 125, 60, 30, 10 and 5,mmol Fe/l were intra-arterially injected into the aorta of a pig. Then the dilution of 10,mmol Fe/l was chosen for repeated intra-arterial injections into two pigs. During these intra-arterial SPIO injections MR images were acquired with a 1.5,T scanner. Signal intensity measurements were performed in the aorta. The signal-to-noise ratio during SPIO bolus passage was significantly less than during baseline conditions (Fisher's F -ratio 159.8, p,<,0.005) or the recovery signal-to-noise ratio (Fisher's F -ratio 144.6, p,<,0.005). Also, confirmation of flow distal to the catheter-tip position was possible. The use of SPIO as a dark blood agent in combination with a bright blood MR imaging sequence is feasible. Temporary loss of intraluminal signal occurs due to local decrease of the signal because of induction of local inhomogeneities after mixture the present blood and SPIO solution. It provides immediate information about blood flow distal to the catheter and is a potentially useful to guide intravascular MR-interventional procedures. Copyright © 2006 John Wiley & Sons Ltd. [source] Evaluating Cardiac Sources of Embolic Stroke with MRIECHOCARDIOGRAPHY, Issue 3 2007Asu Rustemli M.D. The evaluation of patients with stroke includes identifying its etiology in order to appropriately tailor therapy. Currently, the diagnostic work-up includes imaging of the brain, the arteries of the head and neck, the aorta, and the heart. Traditional methods of imaging include magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), duplex ultrasound, and transthoracic echocardiography (TTE) and/or transesophageal echocardiography (TEE). While echocardiography remains a cornerstone in the field of cardiac imaging, MRI is increasingly able to assess for the most common causes of cardioembolic stroke such as left atrial/left atrial appendage thrombus, left ventricular thrombus, aortic atheroma, cardiac masses and patent foramen ovale. This review will focus on the advantages and limitations of echocardiography and cardiac magnetic resonance (CMR) imaging in diagnosing patients suspected of having an embolic stroke and the role these modalities play in clinical practice today. [source] Saphenous Vein Graft Aneurysm Masquerading as a Right Atrial MassECHOCARDIOGRAPHY, Issue 3 2005Leonid Yatskar M.D. We report a case of a large saphenous vein graft (SVG) aneurysm masquerading as a right atrial mass on transesophageal echocardiogram. Cardiac magnetic resonance angiography reliably made a diagnosis of SVG aneurysm extrinsically compressing right atrium. This case illustrates the importance of using combined imaging modalities for the diagnosis and management of cardiac masses. [source] Time course of cerebral hemodynamics in cryptococcal meningitis in HIV-negative adultsEUROPEAN JOURNAL OF NEUROLOGY, Issue 7 2007W.-N. Chang To evaluate the cerebral hemodynamics in cryptococcal meningitis (CM) patients using non-invasive studies. Serial trans-cranial color-coded sonography (TCCS) and magnetic resonance angiography (MRA) studies were performed to measure the cerebral vasculopathy of 12 HIV-negative CM patients. With TCCS, 8 of the 22 middle cerebral arteries (MCAs) showed stenotic velocities, whereas the time-mean velocity (Vmean) of the 20 anterior cerebral arteries (ACAs), 22 posterior cerebral arteries (PCAs), and 12 basilar arteries (BAs) did not. In total, five patients had stenotic velocities, three of whom had bilateral M1 stenosis (<50%), whilst two had unilateral M1 stenosis (<50%). The Vmean of MCA increased from day 1 to day 35 and substantially decreased thereafter. The mean Pulsatility Index (PI) in the studied vessels was higher during the study period. A mismatch of the findings between TCCS and MRA studies were also demonstrated. There was a high incidence and a longer time-period of disturbed cerebral hemodynamics during the clinical course of CM. However, because of the limited case numbers for this study, further large-scale studies are needed to delineate the clinical characteristics and therapeutic influence of cerebrovascular insults in HIV-negative CM patients. [source] Sudden Worsening of Cluster Headache: A Signal of Aneurysmal Thrombosis and EnlargementHEADACHE, Issue 8 2000Juanita G. McBeath MD We report a 55-year-old man presenting with symptoms of cluster headache, including throbbing pain behind the left eye, tearing, and rhinorrhea. Magnetic resonance imaging and magnetic resonance angiography revealed no abnormalities. Two days of intravenous dihydroergotamine resolved his pain. His headaches were somewhat relieved with a treatment regimen of 100 mg of imipramine each night, 40 mg of propranolol twice a day, 250 mg of divalproex three times a day, and dihydroergotamine nasal spray for breakthrough headaches. Two months later, the severity of his pain increased dramatically. Repeat imaging revealed a large thrombosed left posterior communicating artery aneurysm. Following obliterative surgery, his headaches are infrequent and mild and resemble tension headaches. Dramatic changes in headache characteristics can be an indicator of aneurysmal enlargement and thrombosis. This case illustrates the importance of repeat imaging when a patient's headache significantly worsens. [source] On the segmentation of vascular geometries from medical imagesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 1 2010A. G. Radaelli Abstract A comprehensive analysis of vascular morphology and the application of generic models of vascular biomechanics to specific patients require the ability of extracting a geometrical representation of the vascular anatomy from medical images. Owing to the wide range of clinical manifestations of vascular disease and associated imaging modalities and protocols, several segmentation methods have been proposed over the last 20 years and are available in the literature. In this paper, we review the methods of segmentation of angiographic medical images and identify major advantages and disadvantages of state-of-the-art techniques. We further discuss the performance of some of the most popular intensity-based and gradient-based methods using a set of images of peripheral by-pass grafts acquired with magnetic resonance angiography (MRA). We then propose a threshold front method for the segmentation of MRA images and assess its performance using two anatomic scale replica models, reproducing a normal and a stenotic peripheral artery. The threshold front algorithm is a simple, fast and parameter-free (still adaptive) method achieving segmentation errors below pixel resolution. Copyright © 2009 John Wiley & Sons, Ltd. [source] An integrated care pathway to save the critically ischaemic diabetic footINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 6 2006K. El Sakka Summary This prospective study describes and evaluates the efficacy of an integrated care pathway for the management of the critically ischaemic diabetic foot patients by a multidisciplinary team. A weekly joint diabetes/vascular/podiatry ward round and outpatient clinic was established where patients were assessed within 7 days of referral by clinical examination, ankle-brachial-index-pressures, duplex angiogram and transcutaneous oxygen pressures. An angiogram ± angioplasty or alternatively a magnetic resonance angiography prior to surgical revascularisation was performed in patients deemed not suitable for angioplasty based on the above vascular assessment. Between January 2002 and June 2003(18 months), 128 diabetic patients with lower limb ischaemia were seen. Thirty-four (26.6%) patients received medical treatment alone, and 18 (14.1%) were deemed ,palliative' due to their significant co-morbidities. The remaining 76 (59.4%) patients underwent either angioplasty (n = 56), surgical reconstruction (n = 18), primary major amputation (n = 2) or secondary amputation after surgical revascularisation (n = 1). Minor toe amputations were required in 35 patients. The mortality in the intervention group was 14% (11/76). This integrated multidisciplinary approach offers a consistent and equitable service to diabetic patients with critically ischaemic feet and appears to have a beneficial major/minor amputation ratio. [source] Novel Imaging Techniques of the Esophagus Enhancing Safety of Left Atrial AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2005SCOTT J. POLLAK M.D. This report describes different imaging techniques of the esophagus in four patients during radiofrequency catheter ablation of atrial fibrillation in the left atrium. A novel use of a mixture of barium cream and gadolinium diglutamate allowed esophageal imaging during magnetic resonance angiography of the left atrium and pulmonary veins. Barium cream used during computer tomography angiographic imaging of the left atrium and pulmonary veins allowed esophageal imaging. The esophagus was also imaged with an electroanatomic mapping system. Esophageal and left atrial imaging helped to avoid catheter ablation in left atrial tissue overlapping the esophagus. [source] Characterization of a New Pulmonary Vein Variant Using Magnetic Resonance Angiography:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2004Imaging, Incidence, Interventional Implications of the "Right Top Pulmonary Vein" Introduction: Catheter ablation of the pulmonary veins (PVs) for prevention of recurrent atrial fibrillation requires precise anatomic information. We describe the characteristics of a new anatomic variant of PV anatomy using magnetic resonance angiography. Methods and Results: A 1.5-T magnetic resonance imaging system with a body coil or a torso phased-array coil was used before and after gadolinium injection. Magnetic resonance angiograms were acquired with a breath-hold three-dimensional fast spoiled gradient-echo imaging sequence in the coronal plane. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. A newly described variant PV ascending from the roof of the left atrium was found in 3 of 91 subjects. The mean ostial diameter of the roof PV was 7 ± 2 mm, the mean distance from the ostium to the first branching point was 22 ± 8.5 mm, and the mean distance to the right superior PV was 3.3 ± 0.6 mm. Conclusion: We refer to the newly described variant of PV anatomy as the "right top pulmonary vein." It is important to be aware of this anatomic pattern to avoid inadvertent catheter intubation, which can result in misleading mapping results and PV stenosis. (J Cardiovasc Electrophysiol, Vol. 15, pp. 538-543, May 2004) [source] Assessment of Pulmonary Vein Anatomic Variability by Magnetic Resonance Imaging:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2004Implications for Catheter Ablation Techniques for Atrial Fibrillation Introduction: Pulmonary vein (PV) isolation for atrial fibrillation (AF) currently is performed using either an ostial or an extra-ostial approach. The objective of this study was to analyze by three-dimensional (3D) magnetic resonance angiography (MRA) the anatomy of the PVs in order to detect structural variability that would impact the choice of ablation approach. Methods and Results: Three-dimensional MRA was performed in 105 patients undergoing PV isolation. The ostial diameter, branching pattern, and PV angulation were analyzed. Fifty-nine (56%) patients had the typical pattern of 4 PVs with 4 separate ostia, 30 (29%) patients had an additional PV, and 18 (17%) patients had a left common PV trunk. In two patients, there were three right-sided veins and a common left-sided trunk, giving rise to four ostia: three on the right and one on the left. Two different populations of right middle PVs were noted: one where the additional vein projected anteriorly to drain the right middle lobe and one posterior to drain the superior portion of the right lower lobe. The average intrapatient variability in PV diameter was 7.9 ± 4.2 mm. The PV ostium was <10 mm in 26 (25%) patients and >25 mm in 15 (14%) patients. The first branch originated 6.7 ± 2.3 mm from the ostium. The left superior, right superior, right inferior, and left inferior PVs were found to enter the left atrium at the following angles: 32 ± 13°, 131 ± 11°, 206 ± 16°, and 329 ± 14°, respectively. Forty-nine patients (47%) had at least one funnel shaped PV. Conclusion: This largest PV imaging study to date demonstrates that MRA is a valuable tool that allows detection of marked intrapatient and interpatient anatomic variability of the PVs. These findings suggest that, at least in some patients, circumferential extra-ostial left atrial encirclement of the PVs may be preferable to ostial PV isolation. These findings also may have significant implications on the future development of coil- and balloon-based catheter ablation designs for AF ablation. (J Cardiovasc Electrophysiol, Vol. 15, pp. 387-393, April 2004) [source] Novel parameter for the diagnosis of distal middle cerebral artery stenosis with transcranial Doppler sonographyJOURNAL OF CLINICAL ULTRASOUND, Issue 8 2010Suk-Won Ahn MD Abstract Purpose Transcranial Doppler sonography (TCD) is commonly used for the diagnosis of middle cerebral artery (MCA) stenosis. However, TCD indices to predict distal MCA (M2) stenosis have not yet been established. We compared TCD and magnetic resonance angiography (MRA) to validate a new index for the diagnosis of M2 stenosis. Methods Consecutive patients who underwent TCD and MRA were included. Based on MRA, M2 stenosis was defined as >50% narrowing beyond the bifurcation area. TCD index of the M2/M1 ratio was defined as the ratio between the mean flow velocity (MFV) obtained at a depth of 30,44 mm (M2) and a depth of 45,65 mm (M1). Sensitivity and specificity of the M2/M1 ratio were calculated from the receiver operating characteristic curve. The diagnostic yield of elevated MFV (>80 cm/s) and asymmetry index of >30% for M2 stenosis were also investigated. Results Among the consecutive patients, 105 with M2 stenosis were compared with 123 without MCA stenosis. The M2/M1 ratio was significantly higher in the M2 stenosis group (1.10 versus 0.86, p < 0.001). Sensitivity and specificity for M2 stenosis were most satisfying when the M2/M1 ratio of 0.97 was adopted as the cutoff value. Diagnostic yield of the M2/M1 ratio was better than MFV or asymmetry index. Conclusions The M2/M1 ratio may be a highly specific parameter for assessing M2 stenosis with TCD. © 2010 Wiley Periodicals, Inc. J Clin Ultrasound 38:420,425, 2010 [source] Extracranial and intracranial vertebral artery dissection: Long-term clinical and duplex sonographic follow-upJOURNAL OF CLINICAL ULTRASOUND, Issue 8 2008Tiemo Wessels MD Abstract Purpose. To determine the value of color Doppler sonography (CDUS) in the diagnosis and follow-up of patients with extracranial and intracranial vertebral artery (VA) dissection. Method. Thirty-three patients aged 42 ± 12 years with 40 VADS confirmed via digital subtraction angiography (DSA) (n = 37) and magnetic resonance angiography (MRA) (n = 3) were included in the study. All patients were investigated with extracranial CDUS and transcranial CDUS (TCCDUS) over a mean ± SD follow-up period of 42 ± 24 months and occurrence of new ischemic symptoms was assessed. Sonographic results were compared with initial and follow-up angiographic results. Results. At presentation, 24/33 (73%) patients had suffered an ischemic stroke, 5/33 (15%) had a transient ischemic attack (TIA), and 4/33 (12%) were asymptomatic. Two patients had a recurrent vertebrobasilar TIA; there was no recurrent stroke. The initial DSA findings consisted of 14 stenoses, 20 tapered occlusions, and 6 pseudoaneurysms. During follow-up, 63% of the vessels recanalized. Sonographic findings were consistent with angiographic findings in 80% at the initial examination and in 86% during follow-up. The main reason for discordant results was the failure of CDUS to detect pseudoaneurysms. No recurrence occurred in the vertebral arteries (VA), but 1 patient had an asymptomatic carotid artery dissection during follow-up. Conclusion. Recurrent TIA or stroke after VAD appears to be extremely rare, independent of recanalization or persistent occlusion of the affected artery. CDUS and TCCDUS provide reliable follow-up of VAD in all patients presenting with stenosis or occlusion, but do not allow for detection of pseudoaneurysms of the VA. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008 [source] Highly accelerated first-pass contrast-enhanced magnetic resonance angiography of the peripheral vasculature: Comparison of gadofosveset trisodium with gadopentetate dimeglumine contrast agentsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2009Jeffrey H. Maki MD Abstract Purpose: To investigate the blood pool agent gadofosveset trisodium for first-pass, dynamic peripheral contrast-enhanced magnetic resonance angiography (pMRA), and compare the results with a conventional gadolinium contrast agent. Materials and Methods: A total of 16 patients were imaged at 1.5T using a prototype peripheral vascular coil with high SENSE acceleration. Five received gadopentetate dimeglumine (,0.25 mmol/kg), and 11 received gadofosveset trisodium (five standard-dose 0.03 mmol/kg, six high-dose 0.05 mmol/kg). Quantitative contrast-enhancement and qualitative image quality evaluation was compared between agents and doses. Results: High-quality diagnostic images were uniformly obtained. The contrast ratio did not significantly differ between gadopentetate dimeglumine and high-dose gadofosveset trisodium, both of which were greater than standard-dose gadofosveset trisodium. High-dose gadofosveset trisodium was equivalent to gadopentetate dimeglumine in image quality and subjective vessel-to-background ratio, but significantly better for depicting small muscular arteries. Standard-dose gadofosveset trisodium showed equivalent image quality and small artery depiction with a slight but significant decrease in vessel-to-background ratio as compared to gadopentatate dimeglumine. Both gadofosveset trisodium doses trended toward more venous enhancement, but this was not a diagnostic problem. Conclusion: First-pass peripheral CE-MRA using gadofosveset trisodium is feasible, yielding image quality comparable to double to triple-dose gadopentetate dimeglumine. Increasing the gadofosveset trisodium dose to 0.05 mmol/kg yields further improvements. J. Magn. Reson. Imaging 2009;30:1085,1092. © 2009 Wiley-Liss, Inc. [source] Magnetic resonance angiography findings of penile Mondor's diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2009Rafael Boscolo-Berto MD Abstract A 53-year-old male was admitted to our Emergency Department affected by a contemporary high-flow priapism and induration on the dorsal penile surface, in consequence of a prior transrectal prostate biopsy performed 2 weeks earlier on the basis of a suspicion of prostate cancer. We describe a penile Mondor's disease (penile superficial dorsal vein thrombosis) of uncertain pathogenesis involving the penile superficial vein, and employing a careful diagnostic pathway by using magnetic resonance angiography (MRA). In the literature many reports described pulsed- and color-Doppler ultrasonography classical findings about penile Mondor's disease. For the first time we report the pathognomonic features of penile Mondor's disease on MRA, which may be considered a useful and comprehensive tool to deepen the analysis only in the case of a complex clinical picture such as the one presented. J. Magn. Reson. Imaging 2009;30:407,410. © 2009 Wiley-Liss, Inc. [source] MRA of intracranial aneurysms embolized with platinum coils: A vascular phantom study at 1.5T and 3TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2008Shingo Kakeda Abstract Purpose To analyze the influence of matrix and echo time (TE) of three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) on the depiction of residual flow in aneurysms embolized with platinum coils at 1.5T and 3T. Materials and Methods A simulated intracranial aneurysm of the vascular phantom was loosely packed to maintain the patency of some residual aneurysmal lumen with platinum coils and connected to an electromagnetic flow pump with pulsatile flow. MRAs were obtained altering the matrix and TE of 3D TOF sequences at 1.5T and 3T. Results The increased spatial resolution and the shorter TE offered better image quality at 3T. For the depiction of an aneurysm remnant, the high-spatial-resolution 3T MRA (matrix size of 384 × 224 and 512 × 256) with a short TE of ,3.3 msec were superior to the 1.5T MRA obtained with any sequences. Conclusion 3T MRA is superior to 1.5T MRA for the assessment of aneurysms embolized with platinum coils; the combination of the 512 × 256 matrix and short TE (3.3 msec or less) seems feasible at 3T. J. Magn. Reson. Imaging 2008;28:13,20. © 2008 Wiley-Liss, Inc. [source] 3D nongadolinium-enhanced ECG-gated MRA of the distal lower extremities: Preliminary clinical experienceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2008FRANZCR, Ruth P. Lim MBBS Abstract Purpose To report our initial experience implementing a noncontrast-enhanced electrocardiograph (ECG) gated fast spin echo magnetic resonance angiography (MRA) technique for assessment of the calf arteries. Materials and Methods Noncontrast MRA images of 36 clinical patients examined over a 6-month period were evaluated by two radiologists for length and degree of stenosis of arterial segments. Diagnostic confidence in the technique was also recorded. The reference standard was a consensus reading by both radiologists using the noncontrast technique combined with two gadolinium-enhanced techniques: bolus-chase and time-resolved imaging. Results For stenosis evaluation the noncontrast technique demonstrated accuracy 79.4% (1083/1364), sensitivity 85.4% (437/512), and specificity 75.8% (646/852). The sequence demonstrated high negative predictive value (92.3%, 646/700). The technique had serious artifacts leading to poor diagnostic confidence in 17 patients (47.2%). These included motion (n = 7) and artifacts specific to the sequence, including inaccurate trigger delays (n = 5), linear artifact (n = 7), and vessel blurring (n = 5). When only patients in whom there was satisfactory diagnostic confidence were considered, accuracy, sensitivity, and negative predictive value were 92.2% (661/717), 92.4% (158/171), and 97.5% (503/516), respectively. Conclusion Our results indicate that when technically successful, noncontrast-enhanced MRA using ECG-gated fast spin echo can provide accurate imaging of the calf and pedal arteries. However, further development and optimization are needed to improve the robustness of the technique. J. Magn. Reson. Imaging 2008;28:181,189. © 2008 Wiley-Liss, Inc. [source] Coronary MR angiography at 3T during diastole and systoleJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007Ahmed M. Gharib MD Abstract Purpose To investigate the impact of end-systolic imaging on quality of right coronary magnetic resonance angiography (MRA) in comparison to diastolic and to study the effect of RR interval variability on image quality. Materials and Methods The right coronary artery (RCA) of 10 normal volunteers was imaged at 3T using parallel imaging (sensitivity encoding [SENSE]). Navigator-gated three-dimensional (3D) gradient echo was used three times: 1) end-systolic short acquisition (SS): 35-msec window; 2) diastolic short (DS): middiastolic acquisition using 35-msec window; and 3) diastolic long (DL): 75-msec diastolic acquisition window. Vectorcardiogram (VCG) data was used to analyze RR variability. Vessel sharpness, length, and diameter were compared to each other and correlated with RR variability. Blinded qualitative image scores of the images were compared. Results Quantitative and qualitative parameters were not significantly different and showed no significant correlation with RR variability. Conclusion Imaging the RCA at 3T during the end-systolic rest period using SENSE is possible without significant detrimental effect on image quality. Breaking away from the standard of imaging only during diastole can potentially improve image quality in tachycardic patients or used for simultaneous imaging during both periods in a single scan. J. Magn. Reson. Imaging 2007;26:921,926. © 2007 Wiley-Liss, Inc. [source] Whole-body MR angiography using a novel 32-receiving-channel MR system with surface coil technology: First clinical experienceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2005Michael Fenchel MD Abstract Purpose To demonstrate the feasibility of detecting atherosclerotic vascular disease using an innovative magnetic resonance angiography (MRA) protocol in combination with a dedicated whole-body MR scanner with new surface coil technology. Materials and Methods A total of 10 volunteers and eight patients with peripheral arterial occlusive disease (PAOD) were examined at 1.5 T. Conventional digital subtraction angiography (DSA) of the symptomatic region was available as a reference standard in all eight patients. Depending on subjects' size, four to five three-dimensional data sets were acquired using an adapted injection protocol. Images were assessed independently by two readers for vascular pathology. Additionally, signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured. Results Whole-body MRA yielded excellent sensitivity and specificity of more than 95% for both readers with high interobserver agreement (k = 0.93). Surface coil signal reception rendered a high SNR (mean 151.28 ± 54.04) and CNR (mean 120.75 ± 46.47). Despite lower SNR and CNR of the cranial and cervical vessels, a two-step injection protocol exhibited less venous superposition and therefore proved to be superior compared to single-bolus injection. Conclusion Our approach provides accurate noninvasive high-resolution imaging of systemic atherosclerotic disease, covering the arterial vasculature from intracranial arteries to distal runoff vessels. The recently introduced MR scanner and coil technology is feasible to significantly increase the performance of whole-body MRA. J. Magn. Reson. Imaging 2005;21:596,603. © 2005 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||