Use Of Magnetic Resonance Angiography Research Articles

Axial MR Angiography in Evaluating Revascularization after Indirect Bypass Surgery for Moyamoya.

At our institution, revascularization after indirect moyamoya surgery is routinely evaluated using magnetic resonance angiography (MRA) rather than catheter angiography. This study reviews how revascularization can be visualized on axial MRA versus catheter angiography and compares clinical outcomes of surgeries evaluated by routine postoperative MRA versus routine catheter angiography. We reviewed the records of all patients treated at our institution who underwent unilateral encephaloduroarteriosynangiosis (EDAS)/pial synangiosis 2004-2021 at 1-21 years of age. Inclusion criteria included undergoing preoperative MRA within 18 months of surgery and postoperative MRA 3 to 30 months after surgery. Clinical outcome measures included postoperative stroke and transient ischemic attacks (TIAs), changes in symptoms (improved, unchanged, worsened), and new postoperative symptoms. Measures were compared between surgeries evaluated by routine postoperative MRA versus routine postoperative angiograms. For each surgery, we determined the ratios of the diameters and areas of the donor and contralateral corresponding vessels and the relative signal intensities of these two vessels on preoperative- and 3-to-30-month postoperative MRA. We did the same for the middle meningeal artery (MMA) ipsilateral to the donor artery and the contralateral MMA. We assessed changes from pre- to post-operation in diameter ratios, area ratios, relative signal intensity, ivy sign, and brain perfusion on arterial spin labeled (ASL) imaging. MRI and MRA measures of revascularization and flow were compared to Matsushima grades in patients who had postoperative catheter angiograms. Fifty-one operations were included. There were no significant differences in rates of strokes, TIAs, changes or new symptoms after surgeries evaluated by routine postoperative MRA versus catheter angiogram. Significant associations existed between greater collateralization on postoperative MRA and greater median increases in preoperative-to-postoperative ratios of donor-vessel-over-contralateral-vessel diameter (p=0.0461) and ipsilateral-MMA-over-contralateral-MMA diameter (p=0.0135). The median increase in the ratio of the donor-vessel-over-corresponding-contralateral-vessel diameters was significantly higher for Matsushima grade A versus B (p=0.036). The median increase in the ratio of the sum of donor-and-ipsilateral-MMA diameters over the sum of the contralateral vessel diameters was significantly higher for improved-versus-unchanged perfusion on ASL imaging (p=0.0074). There was a nonsignificant association between greater postoperative collateralization on MRA and Matsushima grade (p=0.1160) Conclusion: Cerebral revascularization after EDAS/pial synangiosis can be evaluated on axial MRA by comparing the diameter and/or signal intensity of the donor vessel and ipsilateral MMA to those of the corresponding contralateral vessels on postoperative-versus-preoperative MRA. The use of routine postoperative MRA rather than catheter angiography does not appear to negatively affect outcomes.

Usefulness of silent magnetic resonance angiography (MRA) for the diagnosis of atherosclerosis of the internal carotid artery siphon in comparison with time-of-flight MRA

Background and purposeFlow visualization in 3D time-of-flight MRA (3D-TOF MRA) may be limited for internal carotid artery siphon owing to turbulent artifact. The purpose of this study was to compare the usefulness of Silent MRA and 3D-TOF MRA to assess atherosclerosis of the internal carotid artery siphon.Material and methodsA total of 106 patients with suspected cerebrovascular disease were included. All patients were scanned with Silent MRA and 3D-TOF MRA sequences and also underwent DSA examination. Two observers independently assessed the TOF MRA and Silent MRA images of atherosclerosis of the internal carotid artery siphon. The diagnostic efficacy of two MRA methods in evaluating atherosclerosis of the carotid siphon was performed by using receiver operating characteristic (ROC) curve analysis. Interobserver reliability was also assessed using weighted kappa statistics.ResultsImage of Silent MRA sequence had higher subjective evaluation scores and significantly high CNR between the carotid siphon and the background tissues than the image of 3D-TOF MRA sequence (P < 0.05). The AUC was 0.928 (95% CI 0.909–0.986) for Silent MRA, which was significantly higher than that of 3D-TOF MRA (0.671, 95% CI 0.610–0.801, P < 0.05). Silent MRA had high sensitivity, specificity and accuracy than 3D-TOF MRA for visualization of the carotid siphon.ConclusionsSilent MRA as a new angiographic modality is superior to 3D-TOF MRA for visualization of the carotid siphon, and maybe an alternative to 3D-TOF MRA in the diagnosis of atherosclerosis of the carotid siphon.

Abstract WP176: Compared To Catheter Angiogram MRA Is A Moderate Predictor Of Suzuki Grade In Children With Moyamoya

Introduction: Moyamoya is a progressive cerebral arteriopathy affecting the arteries in the circle of Willis. Suzuki grade for moyamoya using catheter angiogram has been gold standard for the evaluation of moyamoya both in children and adults. Suzuki grade evaluates the amount of stenosis and collateral formation in the cerebral arteries. Magnetic resonance angiography (MRA) non-luminal imaging can overestimate stenosis and underestimate collaterals. With greater use of MRA for diagnosis and follow-up, it is important to understand MRA staging is truly comparable to catheter angiogram. Methods: Study neurologist and interventional radiologist reviewed both catheter angiograms and MRAs without clinical information. The modified Suzuki stage was used to evaluate the MRA. Median time from MRA to catheter angiogram was calculated. Cohen’s Kappa was used to compare modalities of Suzuki grade based on catheter angiogram to modified Suzuki grade by MRA on the same patients. Results: A total of 29 patients with moyamoya were reviewed. Median time between MRA and catheter angiogram was 2.4 months with interquartile range from 0.6-5.3 months. Unweighted Cohen’s Kappa was 0.34 (p&lt;0.0001) which is considered fair correlation. When we calculated a weighted Cohen’s Kappa it improved but only to 0.49 (p&lt;0.0001) which is moderate correlation. Conclusion: Using Cohen’s kappa to compare two methods of evaluating cerebral artery stenosis in children with moyamoya, we demonstrated that there is only moderate correlation between catheter angiogram Suzuki staging compared to modified Suzuki staging with MRA. In conclusion, we suggest caution in the reliance of MRA for diagnosis and follow-up of children with moyamoya. We recommend consideration catheter angiograms at time of diagnosis and with surgical planning.

The utility of magnetic resonance angiography in children with nutcracker syndrome

Background/aim The presented study aimed to evaluate the utility of magnetic resonance angiography (MRA) in the pediatric population with nutcracker syndrome.Materials and methods Patients with suggestive clinical symptoms and laboratory findings and got the diagnosis of nutcracker syndrome with Doppler ultrasonography between January 2011–2019 were included in the study. In addition, children who had renal MRA due to hypertension were evaluated as the control group. MRA images of all patients were examined retrospectively by three radiologists at different levels of experience, and the superior mesenteric artery angle, aorta-mesenteric distance, left renal vein diameter both in the regions of aorta-mesenteric, and renal hilum were recorded. ResultsForty-five patients diagnosed with nutcracker syndrome were included in the study. The mean age of patients was 12 (4–16) and 30 (67%) were female. As the control group, 25 patients with hypertension who had MRA were included and they had a mean age of 12 (1–18) and 19 (76%) were male. The mean superior mesenteric artery angle was 26.5 ° (16–73 ± 12) in the patient group and 57.8 ° (25–139, ± 33) in the control group (p < 0.001); the mean aorta-mesenteric distance was 3.3 mm (1.7–6.5, ± 1.1) in the patient group and 8 mm (3.4–32, ± 5.9) in the control group (p < 0.001). MRA measurements of three radiologists were consistent with each other.ConclusionMRA imaging can be applied as an alternative diagnostic method for Doppler ultrasonography and multidetector CT examinations by radiologists with different experience levels in pediatric patients with nutcracker syndrome.

The Usefulness of Magnetic Resonance Angiography to Analyze the Variable Arterial Facial Anatomy in an Effort to Reduce Filler-Associated Blindness: Anatomical Study and Visualization Through an Augmented Reality Application.

BackgroundThe use of soft tissue fillers for facial rejuvenation is increasing rapidly and the complications, unfortunately, follow the same path. Blindness caused by intravascular filler injections is a rare but devastating complication. Knowledge of the individual arterial anatomy may aid the injector in avoiding injecting into an artery and thus to prevent blindness.ObjectivesTo evaluate if the use of magnetic resonance angiography (MRA) may visualize the arterial facial anatomy in a contrast- and radiation-free way and study the individual arterial variations using an augmented reality (AR) image.MethodsThe individual arterial anatomy of the 3 terminal branches of the ophthalmic artery (supraorbital [SO]; supratrochlear [STr]; and dorsal nasal [DN] arteries) of 20 volunteers was studied by a 3-Tesla MRI, combining infrared (IR) facial warming and 3-dimensional time-of-flight multiple overlapping thin slab acquisition MRA. The resulting visualization of the facial arteries was shown on the patient’s face through AR technology.ResultsThe MRA was able to visualize the SO in 90.0%, STr in 92.5%, and DN arteries in 75% of the examined patients, as well as numerous variations in both vessel localization and path. Furthermore, a proof-of-concept of the AR visualization of the individual arterial anatomy was successfully implemented.ConclusionsDermal filler injectors should be aware of the risk of filler-induced blindness and familiarize themselves with the visualization of the variable facial vascular anatomy. The implementation of a one-time MRA and subsequent AR visualization may be useful in the accurate planning of minimally invasive facial rejuvenation procedures.

The Anatomy of the Circle of Willis Is Not a Strong Enough Predictive Factor for the Prognosis of Cross-Clamping Intolerance during Carotid Endarterectomy.

Carotid endarterectomy (CEA) is safe and effective in reducing the risk of stroke in symptomatic severe carotid artery stenosis. Having information about cross-clamping (CC) intolerance before surgery may reduce the complication rate. The purpose of this study was to assess the usefulness of magnetic resonance angiography (MRA) and magnetic resonance angiography perfusion (P-MR) in determining the risk of CC intolerance during CEA. Material and methods: 40 patients after CEA with CC intolerance were included in Group I, and 15 with CC tolerance in Group II. All patients underwent MRA of the circle of Willis (CoW), P-MR with or without Acetazolamide; P(A)-MR in the postoperative period. Results: CoW was normal in the MRA in three cases (7.5%) in Group I, and in eight (53%) in Group II. We found P-MR abnormalities in all patients from Group I and in 40% from Group II. Using a calculated cut-off point of 0.322, the patients were classified as CC tolerant with 100% sensitivity or as CC intolerant with 95% specificity. After evaluating P-MR or MRA alone, the percentage of false negative results significantly increased. Conclusion: The highest value in predicting cross-clamping intolerance is achieved by using analysis of P(A)-MR and MRA of the CoW in combination.

327 The Incidence of Clinically Significant Magnetic Resonance Angiography Findings for Transient Ischemic Attack Patients in the Observation Unit

Background: A transient ischemic attack (TIA) is no longer considered to be a benign event, rather it is a serious warning for an impending stroke. Studies show that this “transient event” is associated with a 90-day risk of a stroke in approximately 10% of people, with half of these strokes occurring within 48 hours of the inciting event. This critical statistic favors the need for close monitoring and expeditious neurologic workup. With advancements in technology one of the major diagnostic studies for cerebrovascular accident (CVA) is magnetic resonance angiography (MRA). MRA is advantageous as it can detect hyperacute and minute ischemic lesions as well as lesions in the posterior fossa, in addition to aneurysms and arteriovenous malformations. This study serves to evaluate the incidence of clinically significant MRA findings following a TIA, in our emergency department observation unit (EDOU). To determine if there is a significant amount of patients with clinically relevant findings on MRA that may have otherwise gone undiagnosed. Clinical significance is defined as any finding that warrants further workup or intervention. This descriptive study was a retrospective chart analysis of 684 asymptomatic TIA patients admitted to the EDOU, over a 20-month period. Patients were divided by significant or no significant findings for either brain or neck MRA or both. There were no significant findings for either the brain or neck MRA in 70.8% (n=484) of patients. 9.8% (n=67) had significant findings for only the neck MRA. 12.0% (n=82) of patients had significant findings for only the brain MRA. 7.5% (n=51) had significant findings for both brain and neck MRA. Significant findings included moderate to severe vascular stenosis and/or occlusion of the vertebral arteries, carotid, aneurysms (saccular and fusiform), subclavian steal syndrome, and thyroid nodules. Clinically significant findings were noted in 29.4% of the 684 patients. With the use of MRA of the brain and neck, we are discovering more clinically significant findings that may have gone years undiagnosed. Based on this data, it seems fitting that the use of MRI of the brain with MRA of the brain and neck should be utilized for evaluation of TIA patients when able, thus replacing prior workups such as, carotid ultrasound.

Magnetic resonance angiography (MRA) in preoperative planning for patients with 22q11.2 deletion syndrome undergoing craniofacial and otorhinolaryngologic procedures

IntroductionPatients with 22q11.2 deletion syndrome (22q11.2DS) have a variety of anatomic anomalies. For surgeons operating in proximity to the retropharynx, the most pertinent is medial displacement of the internal carotid arteries. The purpose of this study is to describe the preoperative use of magnetic resonance angiography (MRA) in surgical planning and update the incidence rate of medial carotid displacement in patients with 22q11.2DS. MethodsThis is a retrospective cohort study of patients with a confirmed diagnosis of 22q11.2 deletion and preoperative MRA <18 years old who underwent tonsillectomy, adenoidectomy, Furlow palatoplasty (FPP), posterior pharyngeal flap (PPF), sphincter pharyngoplasty (SPP), or submucosal cleft palate (SMCP) repair between January 1st, 2008 and December 31st, 2019. ResultsNinety patients who met the inclusion criteria underwent 133 procedures. The majority identified as Caucasian (84.4%); 52.2% were female. Cervical MRA was more likely to be ordered before a PPF (80.9%) and tonsillectomy (72.7%) over a FPP (47.6%) or adenoidectomy (11.1%). Carotid medialization was visualized in 23 patients (25.6%) and was mild in 11 cases, moderate in 7 cases, and significant in 5 cases. There was no association between sex, race/ethnicity, or genetic diagnosis with carotid medialization. Flap shortening was necessary in 20% of PPF cases to avoid injuring the medialized vessel. ConclusionPatients with 22q11.2DS may have higher rates of medialization of the carotid arteries than previously thought. Given the risk for complications in these patients during pharyngeal operations, there may be a critical place for MRA in surgical planning for patients with 22q11.2DS.

Imaging in the diagnosis and evaluation of peripheral artery disease.

Peripheral artery disease (PAD) is a disease of the systemic arterial tree and is a growing concern globally. It commonly affects the lower extremities and leads to increased mortality and morbidity due to its known association with coronary artery disease and strokes. Over the past several decades, advanced imaging has become a major part in the diagnosis and management of PAD, but there is still no consensus agreement as to the preferred initial imaging test of choice. Over the years, several different trials, reviews, and analyses have compared the three primary imaging modalities in PAD: ultrasound, magnetic resonance angiography (MRA), and computed tomographic angiography (CTA). Overall, the literature suggests that while MRA may have a slight advantage in accuracy, CTA may be the better initial test of choice due to patient comfort and cost-effectiveness. However, each imaging modality has its own risks and contraindications that should be carefully reviewed prior to utilization. This is a review of the current available literature comparing the use of ultrasound, MRA, and CTA in the diagnosis and management of lower extremity PAD.

Clinical Usefulness of Ultra-short TE MRA for Follow-up Imaging after Cerebral Aneurysm Clipping

The aims of this study were to elucidate signal pattern of cerebral aneurysm clip in brain magnetic resonance angiography (MRA) using non-contrast enhanced ultra-short echo time (UTE) sequence and to explore effective utilization of this novel technique for patients, who underwent cerebral aneurysm clipping. The clip was embedded in homemade phantom and scanned using UTE sequence. We investigated characteristic features of the artifacts derived from the clip. Besides, we compared the volume of signal loss between conventional time-of-flight (TOF) and UTE-MRA in 50 patients with the cerebral aneurysm clip. In phantom study, the clip was delineated as signal void area fully surrounded by high signal on original images. On reconstructed short-axial views for the clip, four-leaf clover pattern of artifact was observed when clip was arranged orthogonal to the static magnetic field. On the other hand, this artifact disappeared when the clip was arranged in parallel with the static magnetic field. The volume of signal loss in clinical cases was significantly reduced in UTE-MRA (P < 0.05): 1.30, 0.52-2.77 cm3 for TOF; 0.84, 0.28-1.74 cm3 for UTE (median, range). The scan time for UTE-MRA was 2 minutes and 52 seconds. To understand the characteristic feature of the artifacts from the clip could contribute to define vascular structure in image interpretation. Adding UTE-MRA to routine protocol is useful approach for follow-up imaging after cerebral aneurysm clipping with clinically acceptable prolongation of the scan time.

Screening of extra-coronary arteriopathy with magnetic resonance angiography in patients with spontaneous coronary artery dissection: a single-centre experience.

Current consensus recommends extended vascular investigation in patients with spontaneous coronary artery dissection (SCAD). We here report our experience with the use of magnetic resonance angiography (MRA) for screening extra-coronary arteriopathy in patients presenting with SCAD. Patients presenting with SCAD in a Spanish centre underwent prospective contrast-enhanced MRA to assess the cephalic and abdominopelvic arterial territories. Fibromuscular dysplasia (FMD) was diagnosed following European consensus criteria. Other vascular abnormalities were recorded separately. Two vascular radiologists supervised the acquisitions and independently analysed the results for all cases. Forty patients with SCAD [mean age 50.9±8.6 years, 90% (n=36) women] were included in the study, 12 patients declined to participate and 5 were excluded (metallic implanted devices). All enrolled patients underwent the screening protocol without complications. MRA demonstrated at least one extra-coronary vascular abnormality in 16 patients (40%): 5 (12.5%) were diagnosed with FMD, 6 (15%) showed arterial tortuosity, 3 (7.5%) had non-FMD focal stenoses, and 2 (5%) were found to have small aneurysms at the celiac trunk and splenic artery. No intracranial aneurysms were detected. At a mean follow-up of 4±3 years from the index episode, two cases experienced SCAD recurrences, one in a patient with FMD and the other one in a patient with arterial tortuosity. No deaths or strokes occurred. Systematic extended vascular study with MRA was feasible and demonstrated associated extra-coronary arteriopathy in a substantial proportion of patients presenting with SCAD; however, none required additional intervention or led to vascular events. MRA, being a radiation-free modality, may be the preferred method for screening extracoronary arteriopathy in SCAD, a condition primarily affecting young and middle-age women sensitive to the risks of radiation.

MR angiography and 2-D phase-contrast imaging for evaluation of meso-rex bypass function.

The meso-Rex bypass restores blood flow to the liver in patients with extrahepatic portal vein thrombosis. Stenosis occurs in some cases, causing the reappearance of portal hypertension. Complications such as thrombocytopenia present on a spectrum and there are currently no guidelines regarding a threshold for endovascular intervention. While Doppler ultrasound (US) is common for routine evaluation, magnetic resonance (MR) angiography with two-dimensional phase-contrast MRI (2-D PC-MRI) may improve the assessment of meso-Rex bypass function. To determine the feasibility and utility of MR angiography with 2-D PC-MRI in evaluating children with meso-Rex bypass and to correlate meso-Rex bypass blood flow to markers of portal hypertension. MR angiography and 2-D PC-MRI in meso-Rex bypass patients were retrospectively analyzed. Minimum bypass diameter was measured on MR angiography and used to calculate cross-sectional area. Meso-Rex bypass blood flow was measured using 2-D PC-MRI and divided by ascending aortic flow to quantify bypass flow relative to systemic circulation. Platelet and white blood cell counts were recorded. Correlation was performed between minimum bypass area, blood flow and clinical data. Twenty-five children (median age: 9.5years) with meso-Rex bypass underwent MR angiography and 2-D PC-MRI. The majority of patients were referred to imaging given clinical concern for complications. Eighteen of the 25 patients demonstrated >50% narrowing of the bypass cross-sectional area. The mean platelet count in 19 patients was 127K/μL. There was a significant correlation between minimum cross-sectional bypass area and bypass flow (rho=0.469, P=0.018) and between bypass flow and platelet counts (r=0.525, P=0.021). Two-dimensional PC-MRI can quantify meso-Rex bypass blood flow relative to total systemic flow. In a cohort of 25 children, bypass flow correlated to minimum bypass area and platelet count. Two-dimensional PC-MRI may be valuable alongside MR angiography to assess bypass integrity.

Intermodality variation of aortic dimensions: How, where and when to measure the ascending aorta

BackgroundNo established reference-standard technique is available for ascending aortic diameter measurements. The aim of this study was to determine agreement between modalities and techniques. MethodsIn patients with aortic pathology transthoracic echocardiography, computed tomography angiography (CTA) and magnetic resonance angiography (MRA) were performed. Aortic diameters were measured at the sinus of Valsalva (SoV), sinotubular junction (STJ) and tubular ascending aorta (TAA) during mid-systole and end-diastole. In echocardiography both the inner edge-to-inner edge (I-I edge) and leading edge-to‑leading edge (L-L edge) methods were applied, and the length of the aortic annulus to the most cranial visible part of the ascending aorta was measured. In CTA and MRA the I-I method was used. ResultsFifty patients with bicuspid aortic valve (36 ± 13 years, 26% female) and 50 Turner patients (35 ± 13 years) were included. Comparison of all aortic measurements showed a mean difference of 5.4 ± 2.7 mm for the SoV, 5.1 ± 2.0 mm for the STJ and 4.8 ± 2.1 mm for the TAA. The maximum difference was 18 mm. The best agreement was found between echocardiography L-L edge and CTA during mid-systole. CTA and MRA showed good agreement. A mean difference of 1.5 ± 1.3 mm and 1.8 ± 1.5 mm was demonstrated at the level of the STJ and TAA comparing mid-systolic with end-diastolic diameters. The visible length of the aorta increased on average 5.3 ± 5.1 mmW during mid-systole. ConclusionsMRA and CTA showed best agreement with L-L edge method by echocardiography. In individual patients large differences in ascending aortic diameter were demonstrated, warranting measurement standardization. The use of CTA or MRA is advised at least once.

Utility of MR Angiography in the Identification of Prostatic Artery Origin Prior to Prostatic Artery Embolization

In 17 patients who underwent prostate artery embolization for treatment of lower urinary tract symptoms, the accuracy of preprocedural magnetic resonance (MR) angiography was retrospectively compared with intraprocedural digital subtraction angiography (DSA) in the identification of prostatic artery origin. Of 34 vessels, 26 MR angiography identified origins (76.5%) were confirmed by DSA at the time of embolization. Although image postprocessing is required, the ability of MR angiography to accurately identify prostatic artery origins prior to embolization is useful in treatment planning and can obviate the need for separate computed tomographic angiography, thus reducing both radiation dose and time demand on patients.

An experimental rabbit model of symptomatic cerebral vasospasm with in vivo neuroimaging assessment and ex vivo histological validation.

Cerebral vasospasm (CVS) is a severe complication that occurs following aneurysmal subarachnoid hemorrhage (SAH). Magnetic resonance angiography (MRA) has been used to evaluate brain injury following SAH in humans. The present study was designed to assess a rabbit model of symptomatic CVS (SCVS) and the utility of MRA in evaluating SCVS in rabbits. Japanese white rabbits (n=24) were randomly divided into 2 equal groups: A sham group and a SAH group. Neurological scores were evaluated for 7 days following SAH. Basilar artery (BA) diameters were measured using MRA preoperatively and 7 days postoperatively. Rabbits were sacrificed 7 days following SAH and the BA diameter of each rabbit was determined using histological evaluation. Compared with the Sham group, neurological function was significantly reduced in the SAH group at all time points (P<0.05). Furthermore, the BA diameter was significantly smaller in the SAH group on day 7 compared with the baseline measurement (P<0.05). No significant difference was observed between histological and MRA findings in either group at day 7. Histological changes in the hippocampus consistent with ischemia were observed in the SAH group. Hippocampal ischemia was also identified in the SAH group via MRA and there was no difference in detection rates following the use of MRA and histochemistry. MRA appears to be an effective method for assessing vasospasms of the BA and ischemic changes to the hippocampus in a rabbit model of SCVS. Furthermore, the animal model used in the present study may be beneficial for the future study of SCVS.

Usefulness of the Principle of Selective Excitation Technique Non-electrocardiogramgated 3D-TOF Method in Lower-extremity MRA Using a Whole-body Coil

Generally, non-contrast, lower-extremity, magnetic resonance angiography (MRA) uses electrocardiography; thus, examination is difficult in patients who exhibit arrhythmia. However, the use of electrocardiography can be avoided by using the selective excitation technique in non-electrocardiogram-gated three-dimensional time-of-flight (TOF) (pNon-Gate) MRA. Therefore, patients who exhibit arrhythmia can be examined with pNon-Gate MRA. The purpose of this study was to assess the usefulness of pNon-Gate MRA by using a whole-body coil. Images acquired using pNon-Gate MRA were compared with images acquired using electrocardiogram-gated two-dimensional TOF (Gate) MRA. Comparisons comprised visual evaluation, as well as comparisons of contrast-to-noise ratio and imaging time. In visual evaluation of the pelvic region, Gate MRA showed better results than pNon-Gate MRA. In terms of contrast-to-noise ratio, there were no significant differences in either region. Imaging time showed no significant differences between the two methods. However, it exceeded 30 minutes frequently for Gate MRA, but rarely for pNon-Gate MRA. pNon-Gate MRA is useful in patients with frequent arrhythmia and in those with difficulty in maintaining long-term postures. By using a whole-body coil, pNon-Gate MRA enables easier patient positioning and setting. Therefore, pNon-Gate MRA can be used in routine examinations.

Sonographic Evaluation of the Progression of Takayasu’s Arteritis

Takayasu’s arteritis (TA) is a rare nonspecific inflammatory disease of unknown cause predominantly affecting the aorta and its main branches, coronary arteries, and pulmonary arteries of young females. Diagnosis of TA is typically achieved through computed tomography angiography (CTA) or magnetic resonance angiography (MRA), with sonography often used as a tool for surveillance of disease progression following diagnosis. A case of previously diagnosed TA is presented that demonstrates the effective use of sonography to monitor the progression of the disease with serial examination. The use of CTA and MRA allowed for accurate initial diagnosis, whereas sonography proved to be an effective diagnostic surveillance tool for proper tracking of the disease and its clinical manifestations. Increased sonographer awareness of TA including the clinical manifestations and sonographic characteristics associated with progression of the disease can improve patient outcomes in this potentially life-threatening disease.

Combination of Magnetic Resonance Angiography and Computational Fluid Dynamics May Predict the Risk of Stroke in Patients with Asymptomatic Carotid Plaques.

BackgroundAtherosclerosis plaques in the carotid arteries frequently have been found in patients with stroke. However, the pathogenesis of carotid plaque from asymptomatic to cerebrovascular events is a complex process which is still not completely understood. We aimed to investigate the prognosis of asymptomatic carotid atherosclerotic plaques by use of magnetic resonance angiography (MRA) combined with computational fluid dynamics (CFD).Material/MethodsWe prospectively studied a cohort of 228 participants (mean age 59.21±8.48) with asymptomatic carotid atherosclerotic plaques; mean follow-up duration was 1147.56±224.84 days. Plaque morphology parameters were obtained by MRA analysis. Lumen area (LA) and total vessel area (TVA) were measured, and wall area (WA=TVA−LA) and normalized wall area index (NWI=WA/TVA) were calculated. CFD analysis was performed to evaluate hemodynamic characteristics, including wall pressure (WP) and wall shear stress (WSS). Independent risk factors for stroke were obtained by Cox regression analysis. The area under the curve (AUC) of receiver operator characteristic (ROC) and Z-statistic test were used to evaluate risk factors.ResultsLogistics regression analysis showed NWI (OR: 3.472, 95% CI: 2.943–4.096, P=0.11) and WSS (OR: 6.974, 95% CI: 1.070–45.453, P=0.42) were independent risk factors of stroke for patients with asymptomatic carotid plaques. The area under the ROC curve values for WSS, NWI, and WSS+NWI were 0.772, 0.798, and 0.903, respectively.ConclusionsThe combination of plaque morphology characteristics NWI and hemodynamic parameter WSS may predict the risk of stroke in patients with asymptomatic carotid plaques.

Resistive Factors of the Blood Flow and Energy Distribution in the Body

Purpose of the study is to identify the reason for the formation of the resistive factors in blood flow: inertial flow and turbulence in large arteries and increasing viscosity in the venous blood. Methods and Materials: Blood flow velocities were studied in the different sites of the large vessels in 35 normal adults (15 men, 20 women, age 21 - 49 years) with the use of Magnetic Resonance Angiography. Blood radiodensity (HU) was measured by the CT scanner. Blood flow pulsatility, resistivity indexes were carried out with the Duplex US. Results: Resistive and pulsatility indexes for the ascending aorta are 0.96 ± 0.07 and 3.14. ± 1.7, abdominal aorta 0.91 ± 0.07 and 2.7 ± 1.3, carotid artery 0.74 ± 0.07 and 2.04 ± 0.53, pulmonary trunk 0.74 ± 0.11 and 1.49 ± 0.37, inferior vena cava 0.32 ± 0.21 and 0.69 ± 0.37. Blood radio density (in HU) in the ascending aorta is 57.3 ± 3.5, distal thoracic aorta 25.7 ± 3.1, and inferior vena cava 59.3 ± 3.3. Pulsation of the peak velocity is expressed at the external wall of the isthmus of aorta at the end of systole. Conclusion: Heart energy is stored in the elastic deformation of the blood cells and arterial walls, in kinetic energy of the blood flow, entropy of the system. Inertial blood flow due to the frequency dispersion in the arteries, transforms to the flow with the high fluidity in capillaries. Gibbs free energy increases, enabling spontaneous chemical reaction to proceed across the cell membrane. Process is altered in the venous blood. Changes in resistance express transformation of the energy in the substance.

Diagnostic Strategies Incorporating Computed Tomography Angiography for Pulmonary Embolism

Pulmonary embolism (PE) is a significant cause of morbidity and mortality. The clinical diagnosis of PE can be quite challenging, necessitating a systematic, evidence-based, and cost-effective approach. A sensitive search strategy using keywords associated with PE diagnosis and economic evaluation was conducted. The libraries searched included MEDLINE, EMBASE, Health Technology Assessments, NHS Economic Evaluation Database, and the Cochrane Central Register of Clinical Trials. Studies were required to be a model-based cost-effectiveness analysis (CEA) for PE diagnosis. To be included, studies had to have evaluated both the cost and effectiveness of diagnostic algorithms. In addition, computed tomography (CT) had to have been a component in at least 1 possible algorithm. The characteristics of each CEA were extracted. In addition, the characteristics of CT pulmonary angiography were extracted (sensitivity, specificity, and cost). The most cost-effective strategy and its comparator were presented with the corresponding incremental cost-effectiveness ratio. Thirteen studies met our inclusion criteria. Costs were obtained using a variety of methods. Most studies measured effectiveness using a metric of survival, whereas 3 studies used quality-adjusted life years. Studies varied considerably in terms of the quality of economic evaluation. All but 1 study reported that computed tomographic pulmonary angiography (CTPA)-typically combined with ultrasound or D-dimer-was part of the most cost-effective algorithm. CEA is a useful tool for evaluating potential algorithms for PE diagnosis. Future CEAs would do well to include the use of magnetic resonance angiography and the potential for alternate diagnoses in diagnostic algorithms.