3D Magnetic Resonance Angiography Research Articles

Optimization of 3D contrast‐enhanced pulmonary magnetic resonance angiography in pediatric patients with congenital heart disease

Contrast kinetics were studied in the main pulmonary artery (MPA) and ascending aorta (AAo) of 12 children with congenital heart disease. This information was used to optimize the timing of data acquisition for contrast-enhanced MR angiography in these vessels. To reduce contrast-agent dosage in these fragile patients, contrast enhancement was measured during routine diagnostic 3D magnetic resonance (MR) angiography instead of using test-bolus methods. This was possible by acquiring 2D cross-sectional images of the MPA and AAo during the 3D scan. Time-to-peak in the MPA and AAo was 4.9 +/- 2.2 and 6.1 +/- 2.2 s, respectively, while the transit time between the two vessels was 4.5 +/- 0.6 s. A point-spread-function analysis showed that intravascular signal strength was maximized if data acquisition began 4.7 +/- 2.3 s after the first arrival of contrast in the MPA and 5.6 +/- 2.3 s in the AAo. Little signal loss and artifact resulted when longer acquisition delays were used because contrast-agent clearance was slow. Based on these results, MR angiography of both the MPA and the AAo in children with congenital heart disease can be performed using elliptic-centric k-space sampling and a trigger delay of 7.9 s after contrast arrival in the AAo (i.e., time-to-peak signal strength in the AAo plus one SD to account for intersubject variability).

Automatic extraction of cerebral arteries from magnetic resonance angiography data: Algorithm and validation

We present a cerebral vasculature extraction method from magnetic resonance angiography (MRA) and provide validation for arteries. After reviewing the state-of-the-art in vasculature segmentation techniques, we introduce an automatic algorithm with robust maximal intensity searching and region growing. We present the details of the design and application of extraction validation interface. We demonstrate the artery extraction fidelity of the method with tests on both 3D phantom and real MRA images. We conclude by summarising the proposed algorithm and pointing out possible future pursuits in vessel segmentation.

Portal vein thrombosis: etiology, diagnostic strategy, therapy and management

Myeloproliferative disorder, liver cirrhosis with portal hypertension, deficiency of natural anticoagulant proteins, gene mutation and hepatocellular carcinoma are the most frequent causes of portal vein thrombosis (PVT). Higher accuracy of the diagnostic methods is the reason why today the cause of PVT can be found more frequently. With imaging methods, PVT with or without cavernous transformation can be diagnosed. Fresh thrombus can be undetected in sonography due to the low echogenity but can be recognized in color Doppler sonography, especially with contrast-enhancing agent. Contrast-enhanced 3D MR angiography allows a comparable accuracy in the detection of PVT as digital subtraction angiography. Therapeutical options of PVT consist of mechanical recanalization of the portal vein, local fibrinolysis with or without placement of transjugular intrahepatic portosystemic stent shunt (TIPS), combination of mechanical recanalization and local fibrinolysis, systemic thrombolytic therapy, anticoagulation alone and surgical thrombectomy. Once PVT is found in sonography, Doppler sonography may be performed in order to distinguish benign from malignant thrombus. If further information is needed, MR angiography or contrast enhanced CT is the next step. If these tests are unsatisfactory, digital subtraction angiography should be performed. Until the early nineties, shunt surgery was recommended in patients with PVT who bled despite endoscopic treatment. Today, in symptomatic noncavernomatous PVT, recanalization with local methods is recommended. Additional implantation of TIPS should be performed when the patient is cirrhotic. In recent PVT in non-cirrhotic patients anticoagulation alone is recommended. It is expected that in old PVT anticoagulation can prevent further extension of the thrombus.

3D motion adapted gating (3D MAG): a new navigator technique for accelerated acquisition of free breathing navigator gated 3D coronary MR-angiography

This study aimed to evaluate the influence of a new navigator technique (3D MAG) on navigator efficiency, total acquisition time, image quality and diagnostic accuracy. Fifty-six patients with suspected coronary artery disease underwent free breathing navigator gated coronary MRA (Intera, Philips Medical Systems, 1.5 T, spatial resolution 0.9x0.9x3 mm3) with and without 3D MAG. Evaluation of both sequences included: 1) navigator scan efficiency, 2) total acquisition time, 3) assessment of image quality and 4) detection of stenoses >50%. Average navigator efficiencies of the LCA and RCA were 43+/-12% and 42+/-12% with and 36+/-16% and 35+/-16% without 3D MAG (P<0.01). Scan time was reduced from 12 min 7 s without to 8 min 55 s with 3D MAG for the LCA and from 12 min 19 s to 9 min 7 s with 3D MAG for the RCA (P<0.01). The average scores of image quality of the coronary MRAs with and without 3D MAG were 3.5+/-0.79 and 3.46+/-0.84 (P>0.05). There was no significant difference in the sensitivity and specificity in the detection of coronary artery stenoses between coronary MRAs with and without 3D MAG (P>0.05). 3D MAG provides accelerated acquisition of navigator gated coronary MRA by about 19% while maintaining image quality and diagnostic accuracy.

Pulmonary Vein Imaging: Comparison of 3D Magnetic Resonance Angiography with 2D Cine MRI for Characterizing Anatomy and Size

Pulmonary vein imaging is integral for planning atrial fibrillation ablation procedures. We tested the feasibility of quantifying pulmonary vein ostial diameter using two-dimensional cine cardiac magnetic resonance (2D cine CMR) and three-dimensional magnetic resonance angiography (3D MRA). Nine patients with a history of atrial fibrillation and 20 normal volunteers underwent 2D cine CMR and contrast-enhanced 3D MRA of pulmonary veins on a 1.5 T scanner. Pulmonary vein ostial diameters were measured and pulmonary vein vessel border sharpness was graded qualitatively. Both techniques provided excellent pulmonary vein imaging; however, 3D MRA was faster to perform. The average difference between the systolic and diastolic pulmonary vein diameter was 2.5 mm (23.2%, p < 0.0001) in normal volunteers and 2.2 mm (16.9%, p < 0.0001) in atrial fibrillation patients. The ostial diameter measurements by 3D MRA were significantly larger than on 2D cine CMR. Additionally, the pulmonary vein borders appeared sharper with 2D cine CMR compared to 3D MRA. In conclusion, the 2D images can resolve differences in diameter across the cardiac cycle, while the 3D images provide high quality anatomical depiction but blur borders due to pulsatile motion. We suggest a protocol combining 2D cine CMR and 3D MRA for comprehensive evaluation of pulmonary veins.

Free breathing 3D balanced FFE coronary magnetic resonance angiography with prolonged cardiac acquisition windows and intra‐RR motion correction

A shortcoming of today's coronary magnetic resonance angiography (MRA) is its low total scan efficiency (<5%), as only small well-defined fractions of the respiratory (50%) and cardiac (10%) cycle are used for data acquisition. These precautions are necessary to prevent blurring and artifacts related to respiratory and cardiac motion. Hence, scan times range from 4 to 9 min, which may not be tolerated by patients. To overcome this drawback, an ECG-triggered, navigator-gated free breathing radial 3D balanced FFE sequence with intra-RR motion correction is investigated in this study. Scan efficiency is increased by using a long cardiac acquisition window during the RR interval. This allows the acquisition of a number of independent k-space segments during each cardiac cycle. The intersegment motion is corrected using a self-guided epicardial fat tracking procedure in a postprocessing step. Finally, combining the motion-corrected segments forms a high-resolution image. Experiments on healthy volunteers are presented to show the basic feasibility of this approach.

Magnetic Resonance Imaging Predictors of Coarctation Severity

MRI is increasingly used for anatomic assessment of aortic coarctation (CoA), but its ability to predict the transcatheter pressure gradient, considered the reference standard for hemodynamic severity, has not been studied in detail. This study evaluated the ability of MRI to distinguish between mild versus moderate and severe CoA as determined by cardiac catheterization. The clinical, MRI, and catheterization data of 31 subjects referred for assessment of native or recurrent CoA were reviewed retrospectively. Patients were divided into 2 groups on the basis of peak coarctation gradient by catheterization: <20 mm Hg (n=12) and > or =20 mm Hg (n=19). Patients with cardiac index <2.2 L x min(-1) x m(-2) by catheterization were excluded. By logistic regression analysis, the following variables simultaneously predicted coarctation gradient > or =20 mm Hg: (1) smallest aortic cross-sectional area (adjusted for body surface area) measured by planimetry from gadolinium-enhanced 3D magnetic resonance angiography (OR 1.71 for 10 mm2/m2 decrease, P=0.005) and (2) heart rate-corrected mean flow deceleration in the descending aorta measured by phase-velocity cine MRI (OR 1.68 for 100 mL/s(1.5) increase, P=0.018). For the combination of these variables, a predicted probability >0.38 had 95% sensitivity, 82% specificity, 90% positive and negative predictive values, and an area under the receiver-operator characteristics curve of 0.938. In a subsequent validation study, the prediction model correctly classified 9 of 10 patients, with no false-negatives. The combination of anatomic and flow data obtained by MRI provides a sensitive and specific test for predicting catheterization gradient > or =20 mm Hg.

3D contrast-enhanced MR angiography of the abdominal aorta and its distal branches: Interobserver agreement of radiologists in a routine examination 1

To evaluate the quality of images of the aorta and visceral arteries made at a high level of spatial resolution with thin slices and an optimized acquisition time by three-dimensional contrast-enhanced magnetic resonance angiography (3D CE-MRA). 3D CE-MRA with a 1.4-mm slice thickness and 512-pixel base matrix was done on 62 consecutive patients with a 1.5-T magnetic resonance imaging MRI unit. A bolus test with a power injector was used to calculate the optimal scan delay time. For quantitative evaluation, the signal-to-noise ratio (SNR) was measured in 3 regions of interest. Qualitative image analysis was evaluated independently by two radiologists and graded on a scale of 0-3. Separate analyses were done for the aorta and distal visceral arterial branches. The means SNR values were respectively 56.2 +/- 15.2 (mean +/- SD) for the aorta, 59.2 +/- 15.1 for the celiac trunk, and 57 +/- 15.2 for the superior mesenteric artery, with a homogeneous distribution (P = .99). Consistent enhancement was confirmed by the lack of statistically significant differences between the SNR values. The average score for vessel visualization on source images ranged from good to excellent for different segments. After post-processing of images, the average score for distal arterial segments was significantly improved. The overall agreement between the 2 reviewers in the visualization of definite artery segments was excellent (k = .91). 3D CE-MRA with a 512-pixel base matrix and thin slices can be applied in a reproducible way with excellent depiction and delineation of small vessels. Such a protocol could be used routinely.

Preoperative evaluation of pancreaticobiliary tumor using MR multi-imaging techniques

To evaluate the clinical value of MR multi-imaging techniques in diagnosing and preoperative assessment of pancreaticobiliary tumor. MR multi-imaging techniques, including MR cross-sectional imaging, MR cholangiopancreatography (MRCP) and 3D dynamic contrast-enhanced MR angiography (3D DCE MRA), were performed to make prospective diagnosis and preoperative evaluation in 28 patients with suspected pancreaticobiliary tumors. There were 17 cases of pancreatic adenocarcinoma, 8 cases of biliary system carcinoma and 3 cases of non-neoplastic lesions. Using MR multi-imaging techniques, the accuracy in diagnosing the patients with pancreaticobiliary tumors was 89.3% (25/28). The accuracy in detecting the range of tumor invasion was 80.3% (57/71). The sensitivity, specificity, accuracy, positive and negative predictive value of MR multi-imaging techniques in preoperative assessment of the resectability of pancreaticobiliary tumor were 83.3%, 89.5%, 88.0%, 71.4%, and 94.4%, respectively. There was well diagnostic consistency between MR multi-imaging techniques and CT (kappa = 0.64, P<0.01). The fusion image could be made from MRCP and 3D DCE MRA images. MR multi-imaging techniques can integrate the advantages of various MR images. The non-invasive "all-in-one" MR imaging protocol is the efficient method in diagnosing, staging and preoperative assessment of pancreaticobiliary tumor.

Does Variant Hepatic Artery Anatomy in a Liver Transplant Recipient Increase the Risk of Hepatic Artery Complications After Transplantation?

Our aim was to determine whether variant hepatic artery anatomy in a liver transplant recipient increases the risk of hepatic artery complications after liver transplantation. The study group consisted of 84 patients who underwent gadolinium-enhanced 3D MR angiography before orthotopic liver transplantation in which a branch patch arterial anastomosis at the gastroduodenal takeoff was used. MR angiography studies were retrospectively reviewed and assessed for the presence and type of variant hepatic artery anatomy. The diameter of the distal common hepatic artery was measured. The incidence of posttransplantation hepatic artery stenosis or thrombosis was assessed. Seven (8.3%) of the 84 patients developed hepatic artery complications after transplantation. Of the 24 patients with variant hepatic artery anatomy, five (20.8%) had posttransplantation/ hepatic artery complications. In contrast, only two (3.3%) of the 60 patients with classic hepatic artery anatomy had complications. The higher complication rate in patients with variant hepatic artery anatomy was statistically significant (p < 0.05). The odds ratio was 7.6 (95% confidence interval, 1.4-42.6). The diameter of the distal common hepatic artery was smaller in patients with variant hepatic artery anatomy compared with those with classic hepatic artery anatomy (range, 4.3-7.1 mm [mean, 5.8 mm] vs 4.0-8.9 mm [mean 6.3 mm], p < 0.05), and it was also smaller in patients who had posttransplantation hepatic artery complications compared with those who had no complications (range, 4.2-6.3 mm [mean, 5.2 mm] vs 4.0-8.9 mm, [mean, 6.2 mm], p < 0.01). Variant hepatic artery anatomy in a liver transplant recipient increased the risk of hepatic artery complications after transplantation. The smaller caliber of the native common hepatic artery may contribute to the higher risk.

Noninvasive Detection of Steno-Occlusive Disease of the Supra-Aortic Arteries With Three-Dimensional Contrast-Enhanced Magnetic Resonance Angiography

Concomitant disease of the supra-aortic arteries can influence the outcome of surgical treatment of carotid artery stenosis. However, sensitivity and specificity data of noninvasive contrast-enhanced 3-dimensional (3D) magnetic resonance angiography (CE MRA) for the detection of steno-occlusive disease of the entire supra-aortic arteries including the circle of Willis remain unclear. We aimed to intra-individually compare high-spatial-resolution CE 3D MRA and digital subtraction angiography (DSA) for the assessment of steno-occlusive vascular disease of the supra-aortic arteries. CE MRA and DSA of the supra-aortic arteries were prospectively performed in 50 consecutive patients. Intra-individual comparison of CE MRA and DSA was available in 833 arteries. High-spatial-resolution CE MRA comprised a measured voxel size of 0.81 mm x 0.81 mm x 1 mm (0.66 mm3). Steno-occlusive vascular disease of the 833 arteries was assessed independently by 2 radiologists according to the NASCET criteria. CE MRA had a sensitivity of 100% (73/73), a specificity of 99.3% (760/765), a positive predictive value of 93.6% (73/78), and a negative predictive value of 100% (760/760) by using a 70% to 99% threshold of arterial diameter stenosis. For detection of occlusion, sensitivity, specificity, PPV, and NPV value of CE MRA were 100%, respectively. Noninvasive high-spatial-resolution CE MRA is suited to replace diagnostic DSA for the detection of steno-occlusive disease of the supra-aortic arteries.

Lower Extremity: Low-Dose Contrast Agent Intraarterial MR Angiography in Patients—Initial Results

Institutional review board approval and patient consent were obtained. A low-dose injection protocol for intraarterial three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography was derived from femoral flow phantom studies and prospectively evaluated in patients with peripheral arterial occlusive disease (PAOD). All MR angiograms were obtained at 1.5 T with a T1-weighted gradient-echo sequence. MR angiograms of a gadolinium dilution series (0.8-200.0 mmol/L) were acquired in a femoral phantom at different flow rates. Signal-to-noise ratios (SNRs) above the 75% threshold of the measured maximum were considered optimal. The lowest optimal concentration was injected intraarterially in nine patients to obtain 3D MR angiograms of the thigh and calf station. Contrast-to-noise ratios (CNRs) were calculated for four arterial segments. The low optimal concentration of 50 mmol/L (20-mL bolus volume), about 5% of the total permissible dose, showed SNRs larger than the 75% threshold in the phantom study. In patients, this concentration led to high-spatial-resolution angiograms with mean CNRs of 70.0 +/- 14.5 (+/- standard deviation) for the superficial femoral artery and 47.5 +/- 13.4 at the infrapopliteal level. Low-dose contrast agent intraarterial 3D MR angiography showed high arterial enhancement, enabling assessment of lower extremity arteries in patients with PAOD and multiple injections--a crucial precondition for MR-guided endovascular interventions.

Untreated Tetralogy of Fallot With Pulmonary Atresia in a 55-Year-Old Woman

HomeCirculationVol. 110, No. 18Untreated Tetralogy of Fallot With Pulmonary Atresia in a 55-Year-Old Woman Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBUntreated Tetralogy of Fallot With Pulmonary Atresia in a 55-Year-Old WomanFindings From Magnetic Resonance Imaging Michael Puderbach, Joachim Eichhorn, Christian Fink and Hans-Ulrich Kauczor Michael PuderbachMichael Puderbach From Forschungsschwerpunkt E, Innovative Krebsdiagnostik und -therapie E010, Deutsches Krebsforschungszentrum (DKFZ), (M.P., C.F., H.-U.K.), and the Department of Cardiology, Childrens’ Hospital, University of Heidelberg (J.E.), Heidelberg, Germany. Search for more papers by this author , Joachim EichhornJoachim Eichhorn From Forschungsschwerpunkt E, Innovative Krebsdiagnostik und -therapie E010, Deutsches Krebsforschungszentrum (DKFZ), (M.P., C.F., H.-U.K.), and the Department of Cardiology, Childrens’ Hospital, University of Heidelberg (J.E.), Heidelberg, Germany. Search for more papers by this author , Christian FinkChristian Fink From Forschungsschwerpunkt E, Innovative Krebsdiagnostik und -therapie E010, Deutsches Krebsforschungszentrum (DKFZ), (M.P., C.F., H.-U.K.), and the Department of Cardiology, Childrens’ Hospital, University of Heidelberg (J.E.), Heidelberg, Germany. Search for more papers by this author and Hans-Ulrich KauczorHans-Ulrich Kauczor From Forschungsschwerpunkt E, Innovative Krebsdiagnostik und -therapie E010, Deutsches Krebsforschungszentrum (DKFZ), (M.P., C.F., H.-U.K.), and the Department of Cardiology, Childrens’ Hospital, University of Heidelberg (J.E.), Heidelberg, Germany. Search for more papers by this author Originally published2 Nov 2004https://doi.org/10.1161/01.CIR.0000146789.79192.08Circulation. 2004;110:e461–e462A 55-year-old woman with congenital heart disease and increasing dyspnea at low levels of exertion was referred to our department for imaging. Clinical findings were cyanosis of the lips and clubbing of the fingers. The past medical history included several hospitalizations for dyspnea, tachycardia, recurrent pulmonary embolism, and suspected cerebral embolism.Despite several conventional angiographic studies, the exact classification of the congenital heart disease and the vascular abnormalities had not been made because of the complex cardiovascular morphology. The presumptive diag- nosis was truncus arteriosus type IV. Differential diagnosis included tetralogy of Fallot with pulmonary atresia.To reevaluate the morphology and to assess acute pulmonary, cardiac, and thoracic vessel problems, MRI was performed (Figures 1 to 4). It revealed a ventricular septal defect with overriding aorta, pulmonal atresia with collateral blood supply by major aortopulmonary collateral arteries, and collateral arteries originating from the right phrenic arteries and intercostal arteries. These findings are consistent with tetralogy of Fallot with pulmonary atresia. Download figureDownload PowerPointFigure 1. Coronal-targeted maximum intensity projection (MIP) of a contrast-enhanced 3D magnetic resonance angiography. Lack of pulmonary arteries in pulmonary atresia. Visualization of collateral blood supply of the lungs: Major aortopulmonary collateral arteries (MAPCA) (black arrow) and additional collateral arteries originating from the right phrenic arteries (white arrow) and intercostal arteries (curved arrow).Download figureDownload PowerPointFigure 2. Coronal-targeted maximum intensity projection (MIP) of a contrast-enhanced 3D magnetic resonance angiography. Visualization of predominantly right-sided dilated intercostal arteries representing collateral blood supply to the right lung in pulmonary atresia.Download figureDownload PowerPointFigure 3. Parasagittal-targeted maximum intensity projection (MIP) of a contrast-enhanced 3D magnetic resonance angiography. Visualization of the ventricular septal defect (arrow) with overriding aorta in tetralogy of Fallot.Download figureDownload PowerPointFigure 4. Selected images of 4-chamber view from cardiac cine MRI over the cardiac cycle. Visualization of the ventricular septal defect with overriding aorta. Jet over the ventricular septal defect from the right to the left ventricle representing Eisenmenger’s reaction. LA indicates left atrium; RA, right atrium; LV, left ventricle; RV, right ventricle; Ao, aorta; arrow, ventricular septal defect; and open arrow, jet over the ventricular septal defect).The online-only Data Supplement, which contains Movies I and II, is available with this article at http://www.circulationaha.org.FootnotesCorrespondence to Michael Puderbach, MD, Forschungsschwerpunkt E, Innovative Krebsdiagnostik und -therapie E010, Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. E-mail [email protected] Previous Back to top Next FiguresReferencesRelatedDetailsCited By (2009) Tetralogy of Fallot Congenital Heart Defects, 10.1007/978-3-7985-1719-6_8, (56-67), . November 2, 2004Vol 110, Issue 18 Advertisement Article InformationMetrics https://doi.org/10.1161/01.CIR.0000146789.79192.08PMID: 15520329 Originally publishedNovember 2, 2004 PDF download Advertisement SubjectsAngiographyComputerized Tomography (CT)Heart Failure

Diagnosis of splanchnic artery aneurysms and pseudoaneurysms, with special reference to contrast enhanced 3D magnetic resonance angiography: a review

Splanchnic artery aneurysms are rare. In the past, conventional angiography was the only way to detect them, but today non-invasive techniques are available. Breath-hold contrast-enhanced 3D magnetic resonance angiography has become a routine examination for evaluation of the aorta and its visceral branches. In this article, we briefly discuss the technical aspects of 3D contrast-enhanced magnetic resonance angiography and illustrate various splanchnic artery aneurysms-pseudoaneurysms with their main characteristics.

The use of three-dimensional ultrasound imaging in breast biopsy and prostate therapy

Minimally invasive techniques are rapidly replacing traditional practices because they result in improved benefits for patients, health care providers, payers, employers and hospitals. While two-dimensional (2D) imaging has been used to guide interventional procedures for many decades, the use of three-dimensional (3D) imaging of the anatomy has the potential to provide more accurate and less variable interventional guidance and monitoring options. Although 3D magnetic resonance imaging (MRI), computed tomography (CT) and angiography are important modalities, the development of 3D ultrasound imaging techniques that are capable of acquiring B-mode, color Doppler and power Doppler images, has allowed the development of image-guided therapy and surgery approaches that are making breast biopsy and prostate therapy more accurate and less variable. The use of 3D ultrasound has the potential to provide inexpensive and near real-time views of the anatomy and pathology enabling minimally invasive interventional procedures. In this paper we present the principles and advantages of 3D ultrasound imaging, review some of the implementations techniques, and present new applications in image-guided prostate therapy and breast biopsy.

Decreased venous contamination on 3D gadolinium-enhanced bolus chase peripheral mr angiography using thigh compression.

We evaluated the potential for improving bolus chase peripheral MR angiography in patients with fast arterial flow using thigh compression to prevent venous contamination. We performed bolus chase peripheral MR angiography in 32 consecutive patients in whom the travel time for a contrast agent to reach the popliteal artery trifurcation was less than 25 sec. Thigh compression was applied by a tourniquet (n = 13) or blood pressure cuff inflated to 60 mm Hg (n = 19). We compared the results with those of 36 consecutive patients who underwent angiography without thigh compression. The effect of thigh compression on arterial flow and tissue enhancement was assessed in patients with symmetric travel time in both legs by applying compression to one leg during the time-resolved 2D-projection MR angiography with 6 mL of gadolinium. On 3D bolus chase MR angiography, thigh compression was applied bilaterally. Venous contamination on the 3D images of the calf was graded as 0, none; 1, trace; 2, mild; 3, moderate; and 4, severe. Signal-to-noise ratio was measured in the popliteal artery. Thigh compression slowed the arterial travel time by a mean +/- SD of 4.7 +/- 2 sec (p < 0.001) with a blood pressure cuff and 3.1 +/- 1 sec (p < 0.001) with a tourniquet. Blood pressure cuffs reduced the score of venous contamination on the calf station from 1.9 to 0.4 (p < 0.05) for intermediate flow (contrast travel time, 20-25 sec) and from 2.5 to 0.9 (p < 0.05) for fast flow (< 20 sec). Thigh compression increased the popliteal artery signal-to-noise ratio (81 vs 52, p < 0.001). Thigh compression with blood pressure cuffs inflated to 60 mm Hg slows down arterial flow, increases arterial signal-to-noise ratio, and reduces venous contamination on 3D gadolinium-enhanced bolus chase peripheral MR angiography.

Time-resolved 3D MR angiography of the abdomen with a real-time system.

This study reports on the implementation of a real-time MR acquisition, reconstruction, and display system on standard hardware for 3D contrast-enhanced MR abdominal angiography. The system allows for dynamic imaging of the contrast passage with good spatial resolution in a single breathhold. It is capable of synchronously acquiring and processing multiple coil data. Bolus arrival can be detected confidently from the display of MIP images from sagittal 3D slabs with moderate spatial resolution. Upon detection of the contrast agent, the patient is asked to hold their breath and a novel 3D acquisition is started for a coronal volume. Temporal imaging within the breathhold is achieved through applying a modified time-resolved imaging of contrast kinetics (TRICKS) technique with elliptical centric view ordering. The technique displays contrast passage from the arterial phase through enhancement of the hepatic venous system. It also provides the ability to quantify motion of the diaphragm over a long breathhold.

Major vascular anomalies in Turner syndrome: prevalence and magnetic resonance angiographic features.

Turner syndrome (TS) is associated with aortic coarctation and dissection; hence, echocardiographic evaluation of all patients is currently recommended. X-ray angiography in clinically symptomatic patients has suggested a range of other vascular anomalies, but the true prevalence of such lesions in TS is unknown. To better understand the prevalence and pathogenesis of cardiovascular defects in TS, we prospectively evaluated a group of asymptomatic adult volunteers with TS using magnetic resonance (MR) angiography. A total of 85 adults with TS and 27 normal female adult volunteers underwent gadolinium-enhanced 3D MR angiography. A high prevalence of aortic anomalies was seen in women with TS, including elongation of the transverse arch (49%), aortic coarctation (12%), and aberrant right subclavian artery (8%). Venous anomalies were also prominent, including persistent left superior vena cava (13%) and partial anomalous pulmonary venous return (13%). None of these anomalies were found in healthy female controls. The constellation of elongation of the transverse arch, aortic coarctation, and persistent left superior vena cava was significantly associated with women with TS. Neck webbing and increased thoracic anterior-to-posterior dimension diameters were strong predictors for arterial and venous anomalies. Thoracic vascular anomalies are common in TS, occurring in approximately 50% of a group not preselected for cardiovascular disease. The highly significant association between neck webbing, increased chest diameter, and these vascular anomalies suggests that in utero, centrally localized lymphatic obstruction may contribute to these cardiovascular deformities in TS. Improved recognition of these often-undetected vascular lesions may be important for identification of patients in need of closer cardiovascular monitoring.

Pulsatile motion effects on 3D magnetic resonance angiography: implications for evaluating carotid artery stenoses.

In-plane carotid artery motion during a 3D MR angiography (MRA) scan can significantly degrade the resulting image resolution. This study characterizes the effect of cardiac pulsatility on 3D contrast-enhanced (CE) MRA with elliptical centric acquisitions using a point-spread function (PSF) analysis. Internal carotid artery (ICA) motion was collected from volunteers and patients using both MR and ultrasound (US) scans. After measuring the carotid artery motion displacement, a simulation was performed which calculated the blurring effects for three different protocols: nongated and two different cardiac gating schemes. The motion sensitivity of each protocol was evaluated for different spatial resolutions. The selection of optimal imaging parameters for a given scan time was investigated. The final results showed that cardiac-gated acquisitions only over a limited region of k-space high spatial frequencies are more time-efficient than cardiac gating for the entire k-space, as it allows for higher resolutions to be achieved and for capturing the arterial phase with low spatial frequencies. Selecting the optimal gating parameters depends directly on the motion characteristics of each individual. Our initial clinical experience is presented, and the need for a real-time tool that characterizes motion behavior for each individual as a prescan protocol is discussed.

Feasibility and performance of breath‐hold 3D true‐FISP coronary MRA using self‐calibrating parallel acquisition

Spatial resolution in 3D breath-hold coronary MR angiography (MRA) is limited by imaging time. The purpose of this work was to investigate the feasibility of improving the spatial resolution of coronary MRA using generalized autocalibrating partially parallel acquisition (GRAPPA) and fast imaging with steady state precession (True-FISP) data acquisition. Coronary data were acquired in 10 healthy volunteers. In five volunteers, the data were fully acquired in k-space and decimated for GRAPPA with an outer reduction factor (ORF) of 2. The coil calibration in GRAPPA was improved by segmented least-squares fitting along the frequency-encoding direction. More than 5% of the total k-space lines were required for the calibration to achieve acceptable artifact suppression despite slightly lower signal-to-noise ratio (SNR). In another five volunteers, coronary data were obtained with both conventional and accelerated data acquisitions in the same imaging time. GRAPPA allowed a submillimeter in-plane resolution, and improved coronary artery definition with an acceptable loss of SNR. In conclusion, 3D breath-hold coronary MRA by GRAPPA and True-FISP is highly feasible.