Follow-up of patients with previous treatment for coarctation of the thoracic aorta: comparison between contrast-enhanced MR angiography and fast spin-echo MR imaging

Regular follow-up is required in patients with previous intervention for coarctation of the aorta to detect recoarctation or aneurysm formation. In this study we describe the findings encountered on routine follow-up exams and we compare the use of contrast-enhanced 3D MR angiography (CE MRA) with fast spin-echo MRI (FSE) to study the thoracic aorta after previous intervention. In 51 consecutive patients previously treated for aortic coarctation, 74 MR studies of the thoracic aorta were performed during a 2-year period using CE MRA and FSE MRI. The thoracic aorta was evaluated for abnormalities of course, caliber, shape, and pathology of side branches. The CE MRA and FSE MRI studies were evaluated side by side by consensus of two reviewers evaluating which MR technique depicted the abnormalities of the thoracic aorta the best. Of 74 exams, six clinically important abnormalities were found: four aneurysms and two restenoses. Two small pseudoaneurysms were missed on the FSE studies. Contrast-enhanced MRA was judged to visualize aortic abnormalities better than FSE (47 of 74 MR studies) especially for the transverse aortic arch, coarctation site, left subclavian artery, and aortic arch configuration. For the ascending aorta and distal descending aorta, CE MRA and FSE performed equally well. Aortic diameters measured at four levels in the first 18 MRI studies showed no significant differences in diameter when measured by FSE or CE MRA (p = not significant). Clinically important abnormalities, such as aneurysm formation and restenosis, can be present years after treatment for aortic coarctation. In the regular follow-up of these patients, CE MRA may provide additional diagnostic information compared with FSE and should be included as part of the routine exam. Received: 3 April 2000; Revised: 5 July 2000; Accepted: 7 July 2000     

Magnetic resonance imaging and angiography for the assessment of coarctation of the aorta

Fifteen patients ranging in age from 9 to 25 years (median age 10 years), with coarctation of the aorta, were investigated with magnetic resonance (MR) imaging pre- and postoperatively. Three patients were examined because of suggested re-stenosis. Both MR examination and cineangiography were performed in 11 patients. The two techniques were comparable concerning the evaluation of both the site and the severity of coarctation as well as of the occurrence of collateral vessels. MR was considered suitable to replace angiography in the pre- and postoperative assessment of coarctation. The patients were preferably examined with a surface spine coil with ECG-gated sagittal, transverse and parafrontal images. The parafrontal images were necessary in order to minimize mistakes due to partial volume effects at the coarctation site. A surface coil placed over the sternum considerably improved the visualization of the internal mammary arteries.     

The thoracic aorta studied by MR imaging

Thirty-three patients with a variety of disorders of the thoracic aorta (aneurysm, dissection, Marfan syndrome, coarctation/pseudocoarctation, L-transposition, and Takayasu disease) were evaluated with magnetic resonance (MR) imaging. MR imaging delineated the presence and extent of thoracic aortic aneurysms and showed the relationship of the aneurysm to arch vessels; it also demonstrated intimal flaps and individual lumina in types A and B aortic dissection. Dilation of the ascending aorta in Marfan syndrome and focal narrowing of the aorta in coarctation were well visualized. The anteroposterior and side-to-side relationships of the aorta and pulmonary artery in L-transposition were demonstrated, as were aortic wall thickening and branch vessel narrowing in Takayasu arteritis. Initial experience suggests that MR imaging may provide a noninvasive method for evaluating thoracic aortic disease. Limitations include inferior spatial resolution, occasional difficulty in imaging the entire region of interest in one section, lack of signal from calcifications, and inability to monitor critically ill patients.     

Congenital heart disease: gated MR imaging in 72 patients

Seventy-two patients (aged 2 months to 75 years; mean 23 years) with a variety of congenital anomalies of the heart and great vessels underwent ECG-gated magnetic resonance (MR) imaging using the multisectional spin-echo technique (0.35 Tesla). The ability to define segmental anatomy and intracardiac anomalies on transverse, sagittal, and coronal images was evaluated. MR images were graded as excellent, diagnostic, or nondiagnostic, and MR findings were corroborated by angiography and/or two-dimensional echocardiography. Studies that were considered to be excellent or diagnostic were obtained in 96% of the cases. Visceroatrial situs, the type of ventricular loop, and the relationship of the great vessels could be identified in all patients with studies encompassing the entire heart. Forty-four of 47 abnormalities at the level of the great vessels were identified with MR, including coarctation of the aorta and vascular rings. MR showed 32 of 35 ventricular abnormalities; 2 small ventricular septal defects and 1 Ebstein anomaly were not demonstrated. All of the abnormalities at the atrial level and those of systemic and pulmonary venous return were seen on MR images. Complex cardiac anomalies, such as single ventricles, and the status of the pulmonary arteries were clearly demonstrated, and a good assessment of total and palliative postoperative anatomy was provided.     

MR imaging of congenital anomalies of the aortic arch

Eighteen patients with congenital aortic arch anomalies were evaluated by ECG-gated MR imaging. Transverse images encompassing the heart and thoracic aorta were available in all patients; sagittal or coronal studies were available in 12 patients. Visualization of the aortic arch, its orientation, and the origin and course of the arch vessels was assessed. Associated intracardiac abnormalities were noted, and the effect of aberrant vessels on the trachea or esophagus was determined. Thirteen patients had a right aortic arch. Mirror-image branching was found in 10 cases, and an aberrant left subclavian artery was found in three of these. Three patients had a left aortic arch with aberrant right subclavian artery, and two patients had a double arch. Tracheal compression caused by vascular rings was found in two patients with respiratory symptoms. Corroborating studies (angiography, surgery, CT, and autopsy) in 16 patients confirmed the MR diagnoses in all but one. We conclude that MR could substitute for other techniques as an effective, noninvasive method for the evaluation of congenital aortic arch anomalies.     

MR angiography of the thoracic aorta with an electrocardiographically triggered breath-hold contrast-enhanced sequence.

An electrocardiographically (ECG) triggered breath-hold contrast material-enhanced magnetic resonance (MR) angiography sequence has been developed for imaging the thoracic aorta. A three-dimensional (3D) gradient-echo sequence is used with a contrast material bolus. Forty-nine patients with various aortic abnormalities and five healthy volunteers underwent imaging with the sequence. All studies were performed in a single breath hold. ECG-triggered breath-hold contrast-enhanced MR angiography was tolerated in 48 of the 49 patients. The images demonstrated no respiratory motion artifacts and diminished pulsation artifacts. The cardiac chambers, aortic root, ascending and descending aorta, aortic arch, proximal arch vessels, and proximal coronary arteries were clearly demonstrated and not obscured by ghost artifacts. The 3D data set allowed excellent multiplanar reformation, permitting orthogonal or oblique views of the vascular anatomy. A variety of congenital and acquired abnormalities were clearly identified. When this sequence is used, it is important to evaluate both the maximum-intensity projection and source images. Delayed imaging should be performed to detect late filling. In conjunction with cine MR and T1-weighted spin-echo imaging, ECG-triggered breath-hold contrast-enhanced MR angiography should be considered the technique of choice for imaging the thoracic aorta.     

Suppression of intravascular signal on fat-saturated contrast-enhanced thoracic MR arteriograms

PURPOSE: To assess the prevalence of artifactual signal intensity loss within the aortic arch and proximal branch vessels on fat-saturated contrast material-enhanced magnetic resonance (MR) arteriograms of the thoracic aorta and to hypothesize about the cause of the loss of signal intensity. MATERIALS AND METHODS: Between January and June 1998, 105 consecutive MR arteriograms of the thoracic aorta were acquired in 103 patients at 1.5 T. Imaging included an arterial phase three-dimensional (3D) fat-saturated contrast-enhanced gradient-echo (GRE) sequence followed by a delayed two-dimensional (2D) transverse fat-saturated GRE sequence. All MR images were reviewed by two radiologists who were blinded to patient history and results of imaging studies and who evaluated the images for the presence of intraluminal loss of signal intensity in the aortic arch and the proximal branch vessels. RESULTS: Intravascular loss of signal intensity was present in at least one vessel on 23 of the 105 arterial phase 3D studies. Seventy-one of 91 left subclavian arterial segments had loss of signal intensity on the delayed 2D studies. CONCLUSION: Intravascular signal intensity loss can be present on contrast-enhanced fat-saturated images of the aortic arch and proximal branch vessels, particularly the left subclavian artery. This phenomenon, which is to the authors' knowledge previously unreported and which is hypothesized to result from undesired water saturation, should not be misinterpreted as stenotic or occlusive vascular disease.     

Thoracic aortic coarctation: MRI evaluation and follow-up]

PURPOSE: Report our experience in the evaluation and follow-up of thoracic aortic coarctation with MRI and describe its role to estimate trans-stenotic flow. MATERIAL AND METHODS: 43 MR examinations were performed in 30 patients (age range 15 days to 73 years) referred to our institution in the last 7 years. RESULTS: MRI visualized the ascending, horizontal and descending portions of the aorta and the supra-aortic vessels in 42/43 patients. MRI clearly identified preoperatively an aortic coarctation in 11/12 cases confirmed by surgery. Postoperatively MRI depicted 4 restenosis and one aneurysm. In 5 patients MRI demonstrated pseudo-coarctation. A significant correlation was established between the maximal trans-stenotic pressure gradient when measured by Doppler US or angiography and the size of the signal void measured on cine-MR images (r=0.72; p<0.01). CONCLUSION: MRI is a reliable non invasive investigation method for the diagnosis and semi-quantitative evaluation of aortic coarctation particularly when colour Doppler US is not satisfactory.     

Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: correlation to morphological imaging of collateral vessels.

PURPOSE: To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow. MATERIALS AND METHODS: Thirteen children with coarctation were examined with T1-weighted spin-echo (T1-W SE) imaging and 3D contrast-enhanced magnetic resonance angiography (MRA). MR velocity mapping was performed at four levels in the descending aorta. RESULTS: The flow immediately above and below the coarctation did not differ significantly. Measuring within the coarctation resulted in flow overestimation. The increase of flow from proximal to distal aorta was 12 +/- 21% in patients with no or uncertain collaterals and 69 +/- 55% in patients with pronounced collaterals. Spin-echo images and MRA were comparable in visualizing collateral vessels. The visual estimation of collaterals correlated reasonably well with flow quantification MR velocity mapping. CONCLUSION: Collateral flow assessment with MR velocity mapping is an accurate technique for evaluating the hemodynamic importance of a coarctation and is recommended if abundant collaterals are not visualized with spin echo or MRA.     

Follow-up of aortic dissection: Contribution of MR angiography for evaluation of the abdominal aorta and its branches

Spin-echo MR is an established method to evaluate thoracic aortic dissections, but is not well suited to study the abdominal aorta. In this study we evaluated whether MR angiography could provide a complete examination of the abdominal aorta. In 28 patients (40 MR studies) with suspected (n=6) or known (n=34) aortic dissection, MR studies were performed. Thoracic aorta was evaluated with spinecho and gradient-recalled-echo MR imaging. Axial two-dimensional time-of-flight MR angiography with thin overlapping slices was used to study the abdominal aorta. Intermediate and high signal intensity on MR angiography was interpreted as patent flow, and low signal was interpreted as thrombus. The presence of an intima flap and the re-entry site could be depicted in all MR studies. Thrombus in the false channel was seen in 8 studies. The origin of the abdominal visceral branches and their relation to the false-true channel could be depicted, except in 4 of 80 renal arteries studied. Extension of the dissection into the coeliac trunk was seen in 2 and in the superior mesenteric artery in 10 studies. Dilatation of the suprarenal abdominal aorta was seen in 20 studies, and of the infrarenal aorta in 9 studies. MR angiography provides valuable information about the abdominal aorta and its branches in patients with aortic dissection. This makes MR imaging appealing as the preferred imaging modality for the diagnosis and follow-up of aortic dissection.     

Peripheral vascular disease: correlation of MR imaging and angiography

The capability of magnetic resonance (MR) imaging for detecting aortic, iliac, and femoral stenoses and occlusions was evaluated. Multisection spin-echo studies at 0.35 tesla were obtained of the infrarenal aorta to the femoral bifurcation in 24 patients, all of whom had undergone intraarterial angiography within 14 days of imaging. Transaxial MR images were compared with the angiograms. Arterial stenoses and occlusions in these vessels detected by MR imaging correlated with angiographic findings in 91% of the instances. Protrusional atherosclerotic plaques and occlusions and stenoses in the aortoiliac region were demonstrated accurately on MR images; complications of previous vascular surgery, such as aneurysms at sites of previous anastomoses or endarterectomy, were also identified. Due to the limited spatial resolution, MR images failed to demonstrate some femoral stenoses. MR imaging may be used for evaluation of aortoiliac vascular disease and for follow-up study after surgical revascularization. However, the limited spatial resolution, noncomposite display of the aortoiliofemoral circulation, and lack of evaluation of peripheral runoff provided by current MR imaging techniques militate against its replacing angiography prior to vascular intervention.     

3-dimensional magnetic resonance angiography in apnea with the rapid infusion of a paramagnetic contrast medium in studying the thoracic aorta

INTRODUCTION: We investigated the diagnostic accuracy of gadolinium-enhanced 3D MRA in the assessment of thoracic aortic diseases. MATERIAL AND METHODS: Thirty-eight patients with diagnosed or suspected conditions of thoracic aorta were examined with contrast-enhanced MRA. All the examinations were performed with a 1.5 T superconductive magnet acquiring breath-hold 3D fast Gradient-Echo (GE) sequences (TR = 5.9 ms; TE = 1.2 ms; FA = 45 degrees; FOV = 48 cm; thickness = 2-2.5 mm; locs = 30-32; TA = 22-24 s; MA = 512) on the coronal plane. The contrast agent was injected bolus after a bolus-test to evaluate circulation time. RESULTS: Three-dimensional gadolinium-enhanced MRA permitted to correctly diagnose aneurysm in 18 patients, dissection in 13 patients and coarctation in 3 patients. In the former the size and extent of the aneurysmal lumen and its relationship to aortic side branches was demonstrated. As for dissections we evaluated the following parameters: 1) type; 2) presence of intimal flap; 3) thrombosis of the false lumen; 4) dilatation of the aorta; 5) assessment of great vessel origins. MRA data were correlated with those of biplane transesophageal esophageal echocardiography, conventional MRI and spiral CT. In the three patients with aortic coarctation the site of coarctation was correctly identified, the degree of aortic narrowing evaluated and the collateral vessels demonstrated. CONCLUSIONS: In our opinion contrast-enhanced three-dimensional MR angiography should be the screening technique of choice in the evaluation of thoracic aorta thanks to its low invasiveness, short acquisition time, large field of view and morphologic resolution. ECG gating is not needed. Limitations are found in the study of wall and periaortic region which are better evaluated with conventional MR imaging.     

Coarctation of the aorta: MR imaging in late postoperative assessment

Thirty-six patients were studied with magnetic resonance (MR) imaging 2-29 years after repair of coarctation of the aorta, and the findings were compared with clinical data and results of echocardiography, catheterization, angiography, and surgery. A satisfactory echocardiographic examination of the isthmus was achieved in 28 patients. Comparison with data from gradient measurements at catheterization and Doppler ultrasound shows that the reduction of lumen diameter correlates well with the gradient and that restenosis at the site of the repair can be suspected when the percentage of stenosis at the isthmus is greater than 50%. MR imaging showed a Dacron patch aneurysm in three patients. Cine MR imaging showed systolic signal loss in the ascending aorta that was presumed to be due, among other factors, to turbulent flow generated from a bicuspid valve. Similar signal loss was seen in the descending aorta distal to the site of the coarctation repair, but this was not related to the presence or absence of a gradient. Aortic compliance measured from transverse MR systolic and diastolic images was abnormally low, suggesting it may be a factor causing systolic hypertension after coarctation repair. MR imaging is a reliable and accurate noninvasive method likely to supersede other methods of assessing the aorta and isthmus following coarctation repair.     

Aorta and runoff vessels: single-injection MR angiography with automated table movement compared with multiinjection time-resolved MR angiography--initial results

The authors compared two techniques for performing runoff, contrast material-enhanced magnetic resonance (MR) angiography. Multiinjection time-resolved imaging of contrast kinetics (TRICKS) and single-injection bolus-chase MR angiographic examinations were performed in 10 volunteers and 10 patients. Image quality and venous overlay of the major blood vessels of the abdomen, thigh, and calf were evaluated. Significantly more (P <.05) vessels were depicted with diagnostic quality on multiinjection TRICKS than on single-injection bolus-chase MR angiographic images.     

MR imaging of Sturge-Weber syndrome: role of gadopentetate dimeglumine and gradient-echo techniques

Five patients with Sturge-Weber syndrome were evaluated by conventional noncontrast spin-echo MR imaging, a gradient-recalled echo (GRE) technique, and T1-weighted spin-echo imaging after administration of gadopentetate dimeglumine. In four of five cases the full extent of intracranial disease was appreciated only on the postcontrast images. In one patient precontrast and GRE images were entirely normal, while only the postcontrast study demonstrated extensive involvement of both brain and retina. Nevertheless, some abnormal vessels with higher flows were seen better on precontrast T2-weighted images than on postcontrast T1-weighted images. GRE techniques demonstrated calcifications to best advantage, in one case even better than on CT. Contrast enhancement with gadopentetate dimeglumine is necessary for the complete MR evaluation of patients with suspected Sturge-Weber syndrome. Traditional noncontrast T2-weighted and GRE images may provide additional complementary information.     

Rotator cuff interval: evaluation with MR imaging and MR arthrography of the shoulder in 32 cadavers

PURPOSE: The purpose of this work was to establish the optimal means of evaluation of the rotator cuff interval (RCI) and rotator interval capsule and demonstrate normal anatomy of the RCI using MR imaging and MR arthrography. METHOD: MR arthrography was performed in 32 cadaveric shoulders. In 20 cases, MR imaging was completed prior to arthrography. Pre- and postarthrography studies included standard imaging planes. Images were evaluated by the consensus of two musculoskeletal radiologists with attention to the RCI, rotator interval capsule (measurements on postarthrographic studies), and crossing structures. In five cases, specialized imaging planes were performed after arthrography. RESULTS: The RCI, rotator interval capsule, and crossing structures were best evaluated by MR arthrography. The anteroposterior dimension of the rotator interval capsule could be best depicted on postarthrogram images. CONCLUSION: MR arthrography, with both standard and specialized imaging planes, is a useful way to evaluate the RCI, the rotator interval capsule, and its crossing structures.     

SCTA及CT血管仿真内镜在主动脉弓缩窄和离断的评价(附3例报告)

目的：研究SCTA和血管领导 具内镜在主动脉弓缩窄和离断诊断中的应用价值。检查方法和影像学表现。方法：对3例主动脉弓缩窄和离断的患者进行静脉注射对比剂容积扫描。利用后处理技术重建成三维图像和仿真内镜图像，并经动脉造影和手术证实。结果：CTA清晰显了纵隔内血管的解剖细节，配合血管仿真内镜，可对此二种疾病进行分型及诊断。结论：SCTA及血管仿真内镜作为一种无创性血管造影技术。对诊断主动脉弓缩窄和主动脉弓离断有重要价值。     

Comparison of 3.0- and 1.5-T three-dimensional time-of-flight MR angiography in moyamoya disease: preliminary experience

PURPOSE: To prospectively compare 3.0- and 1.5-T three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography in patients with moyamoya disease, with special emphasis on the visualization of abnormal netlike vessels (moyamoya vessels). MATERIALS AND METHODS: Study protocols were approved by the local ethics committee; written informed consent was obtained from all patients. The study included 24 consecutive patients with moyamoya disease (four male and 20 female patients). Patients ranged in age from 17 to 66 years (mean age, 41 years). Moyamoya disease had been diagnosed in all patients before they were entered into the study. All patients underwent 3D TOF MR angiography at both 3.0 and 1.5 T; imaging examinations were performed within 14 days of each other. Maximum intensity projections (MIPs) obtained with MR angiography performed at both 3.0 and 1.5 T were evaluated by two neuroradiologists; the visualization of moyamoya vessels was graded according to a 4-point scale. For both 3.0- and 1.5-T imaging, the number of high-signal-intensity areas and the summation of cross-sectional areas of high signal intensity on source images obtained at the same level of MR angiography were compared quantitatively by using the Wilcoxon matched-pair signed-rank test. RESULTS: Moyamoya vessels were better visualized on MIPs obtained with 3.0-T imaging than on MIPs obtained with 1.5-T imaging (P < .001). At the identical level of the source image, 3.0-T imaging depicted more high-signal-intensity areas than did 1.5-T imaging. Wider cross-sectional areas of moyamoya vessels were visualized with 3.0-T imaging than with 1.5-T imaging (P < .001). CONCLUSION: Moyamoya vessels are better depicted with MR angiography at 3.0 T than at 1.5 T.     

Obscured aortic arch on the lateral view as a sign of coarctation

Forty patients with coarctation of the aorta were compared with 80 normal subjects matched by sex and age. The aortic arch was invisible on the lateral radiograph in 84% of patients preoperatively and 88% postoperatively. Only 6 normal subjects (8%) had a similar finding. The authors conclude that an obscured aortic arch on the lateral view could be a clue to the presence of coarctation. Possible explanations for this phenomenon include (a) dilatation of the brachiocephalic arteries (particularly the left subclavian artery), obscuring the superior margin of the arch; (b) hypoplasia and anteromedial displacement of the distal portion of the arch; and (c) diffuse hypoplasia of the arch combined with focal coarctation.     

MR imaging of autopsy-proved paraneoplastic limbic encephalitis in non-Hodgkin lymphoma

We report the case of a 26-year-old man with precursor T-cell acute lymphoblastic leukemia who developed paraneoplastic limbic encephalitis that was diagnosed on the basis of MR imaging findings and was proved post mortem. In our MR imaging studies, fluid-attenuated inversion recovery images and diffusion-weighted echo-planar images clearly depicted bilateral involvement of the medial temporal lobes and multifocal involvement of the brain, whereas T2-weighted turbo spin-echo images failed to show the changes.