AHA scientific statement. Magnetic resonance angiography : update on applications for extracranial arteries

CIRSE Standards of Practice on Carotid Artery Stenting

BACKGROUND

Carotid artery stenting has been used effectively to treat internal carotid artery stenosis since 1989 (Mathias et al. in World J Surg. 25(3):328-34, 2001), with refined and expanded techniques and tools presently delivering outstanding results in percutaneous endoluminal treatment of carotid artery stenosis.

PURPOSE

This CIRSE Standards of Practice document is directed at interventional radiologists and details the guidelines for carotid artery stenting, as well as the different implementation techniques. In addition to updating all previously published material on the different clinical indications, it will provide all technical details reflective of European practice for carotid artery stenting. CIRSE Standards of Practice documents do not aim to implement a standard of clinical patient care, but rather to provide a realistic strategy and best practices for the execution of this procedure.

METHODS

The writing group, which was established by the CIRSE Standards of Practice Committee, consisted of five clinicians with internationally recognised expertise in carotid artery stenting procedures. The writing group reviewed existing literature on carotid artery stenting procedures, performing a pragmatic evidence search using PubMed to select relevant publications in the English language from 2006 to 2022.

RESULTS

Carotid artery stenting has an established role in the management of internal carotid artery stenosis; this Standards of Practice document provides up-to-date recommendations for its safe performance.

Relaxation-Enhanced Angiography Without Contrast and Triggering (REACT) for Fast Imaging of Extracranial Arteries in Acute Ischemic Stroke at 3 T

Purpose

To evaluate a novel flow-independent 3D isotropic REACT sequence compared with CE-MRA for the imaging of extracranial arteries in acute ischemic stroke (AIS).

Methods

This was a retrospective study of 35 patients who underwent a stroke protocol at 3 T including REACT (fixed scan time: 2:46 min) and CE-MRA of the extracranial arteries. Three radiologists evaluated scans regarding vessel delineation, signal, and contrast and assessed overall image noise and artifacts using 5-point scales (5: excellent delineation/no artifacts). Apparent signal- and contrast-to-noise ratios (aSNR/aCNR) were measured for the common carotid artery (CCA), internal carotid artery (ICA, C1 segment), and vertebral artery (V2 segment). Two radiologists graded the degree of proximal ICA stenosis.

Results

Compared to REACT, CE-MRA showed better delineation for the CCA and ICA (C1 and C2 segments) (median 5, range 2–5 vs. 4, range 3–5; P < 0.05). For the ICA (C1 and C2 segments), REACT provided a higher signal (5, range 3–5; P < 0.05/4.5, range 3–5; P > 0.05 vs. 4, range 2–5) and contrast (5, range 3–5 vs. 4, range 2–5; P > 0.05) than CE-MRA. The remaining segments of the blood-supplying vessels showed equal medians. There was no significant difference regarding artifacts, whereas REACT provided significantly lower image noise (4, range 3–5 vs. 4 range 2–5; P < 0.05) with a higher aSNR (P < 0.05) and aCNR (P < 0.05) for all vessels combined. For clinically relevant (≥50%) ICA stenosis, REACT achieved a detection sensitivity of 93.75% and a specificity of 100%.

Conclusion

Given its fast acquisition, comparable image quality to CE-MRA and high sensitivity and specificity for the detection of ICA stenosis, REACT was proven to be a clinically applicable method to assess extracranial arteries in AIS.

Electronic supplementary material

The online version of this article (10.1007/s00062-020-00963-6) contains supplementary material, which is available to authorized users.

Non-Contrast-Enhanced Carotid MRA: Clinical Evaluation of a Novel Ungated Radial Quiescent-Interval Slice-Selective MRA at 1.5T

BACKGROUND AND PURPOSE

Non-contrast-enhanced MRA techniques have experienced a renaissance due to the known correlation between the use of gadolinium-based contrast agents and the development of nephrogenic systemic fibrosis and the deposition of gadolinium in some brain regions. The purpose of this study was to assess the diagnostic performance of ungated non-contrast-enhanced radial quiescent-interval slice-selective MRA of the extracranial supra-aortic arteries in comparison with conventional contrast-enhanced MRA in patients with clinical suspicion of carotid stenosis.

MATERIALS AND METHODS

In this prospective study, both MRA pulse sequences were performed in 31 consecutive patients (median age, 68.8 years; 19 men). For the evaluation, the cervical arterial system was divided into 35 segments (right and left side). Three blinded reviewers separately evaluated these segments. An ordinal scoring system was used to assess the image quality of arterial segments and the stenosis grading of carotid arteries.

RESULTS

Overall venous contamination in quiescent-interval slice-selective MRA was rated as "none" by all readers in 84.9% of cases and in 8.1% of cases in contrast-enhanced MRA (P < .0001). The visualization quality of arterial segments was considered good to excellent in 40.2% for the quiescent-interval slice-selective MRA and in 52.2% for the contrast-enhanced MRA (P < .0001). The diagnostic accuracy of ungated quiescent-interval slice-selective MRA concerning the stenosis grading showed a total sensitivity and specificity of 85.7% and 90.0%, respectively.

CONCLUSIONS

Ungated quiescent-interval slice-selective MRA can be used clinically as an alternative to contrast-enhanced MRA without a significantly different image quality or diagnostic accuracy for the detection of carotid stenosis at 1.5T.

Ungated nonenhanced radial quiescent interval slice-selective (QISS) magnetic resonance angiography of the neck: Evaluation of image quality

BACKGROUND

Standard-of-care time-of-flight (TOF) techniques for nonenhanced magnetic resonance angiography (NEMRA) of the carotid bifurcation and other cervical arteries often provide nondiagnostic image quality due to motion and flow artifacts.

PURPOSE

To perform an initial evaluation of an ungated radial quiescent-interval slice-selective (QISS) technique for NEMRA of the neck, in comparison with 2D TOF and contrast-enhanced magnetic resonance angiography (CEMRA).

STUDY TYPE

Retrospective.

POPULATION

Sixty patients referred for neck MR angiography.

FIELD STRENGTH/SEQUENCE

Ungated radial QISS at 3T.

ASSESSMENT

Three radiologists scored image quality of 18 arterial segments using a 4-point scale (1, nondiagnostic; 2, fair; 3, good; 4, excellent), and two radiologists graded proximal internal carotid stenosis using five categories (<50%, 50-69%, 70-99%, occlusion, nondiagnostic).

STATISTICAL TESTS

Friedman tests with post-hoc Wilcoxon signed-rank tests; unweighted Gwet's AC1 statistic; tests for equality of proportions.

RESULTS

Ungated radial QISS provided image quality that significantly exceeded 2D TOF (mean scores of 2.7 vs. 2.0, 2.7 vs. 2.2, and 2.9 vs. 2.3; P < 0.001, all comparisons), while CEMRA provided the best image quality (mean scores of 3.6, 3.7, and 3.5 for the three reviewers). Interrater agreement of image quality scores was substantial for CEMRA (AC1 = 0.70, P < 0.001), and moderate for QISS (AC1 = 0.43, P < 0.001) and TOF (AC1 = 0.41, P < 0.001). Compared with TOF, QISS NEMRA provided a significantly higher percentage of diagnostic segments for all three reviewers (91.0% vs. 71.7%, 93.5% vs. 72.9%, 95.5% vs. 85.2%; P < 0.0001) and demonstrated better agreement with CEMRA for grading of proximal internal carotid stenosis (AC1 = 0.94 vs. 0.73 for reviewer 1, P < 0.05; AC1 = 0.89 vs. 0.68 for reviewer 2, P < 0.05).

DATA CONCLUSION

In this initial study, ungated radial QISS significantly outperformed 2D TOF for the evaluation of the neck arteries, with overall better image quality and more diagnostic arterial segments, and improved agreement with CEMRA for grading stenosis of the proximal internal carotid artery.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1798-1807.

A New Septum in the Female Breast

BACKGROUND

Understanding the female breast fascial system is of paramount importance in breast surgery. Little was written about breast ligaments. Most articles refer to Cooper's work without further anatomical studies. Lately, a horizontal septum has been described conveying nerves and vessels to the nipple areola complex.

METHODS

During the surgical dissection of the lower part of the breast, in supero-medial technique for breast reduction operations, a fascial septum between the lower two quadrants was detected. This fibrous septum was studied through anatomic dissection of breast tissues during routine breast reshaping procedures that was done on 30 female patients. Magnetic resonance imaging (MRI) was performed preoperatively in all cases and correlated with the intraoperative findings. In the other five cases, outside the clinical study, the imaging was done during routine investigation for breast swellings.

RESULTS

A vertical septum was identified in the lower part of the breast, lying at the breast meridian between the two lower quadrants. It is a tough bi-laminated structure that extends from the middle of the infra-mammary crease caudally to nipple-areola complex cranially and from the pectoral fascia posteriorly to the overlying skin anteriorly. This was proved by MRI findings.

CONCLUSIONS

This study describes a new inferior vertical septum which separates the lower half of the breast into two definite anatomical compartments: medial and lateral.

Imaging Carotid Atherosclerosis Plaque Ulceration: Comparison of Advanced Imaging Modalities and Recent Developments

Atherosclerosis remains the leading cause of long-term mortality and morbidity worldwide, despite remarkable advancement in its management. Vulnerable atherosclerotic plaques are principally responsible for thromboembolic events in various arterial territories such as carotid, coronary, and lower limb vessels. Carotid plaque ulceration is one of the key features associated with plaque vulnerability and is considered a notable indicator of previous plaque rupture and possible future cerebrovascular events. Multiple imaging modalities have been used to assess the degree of carotid plaque ulceration for diagnostic and research purposes. Early diagnosis and management of carotid artery disease could prevent further cerebrovascular events. In this review, we highlight the merits and limitations of various imaging techniques for identifying plaque ulceration.

Nonenhanced hybridized arterial spin labeled magnetic resonance angiography of the extracranial carotid arteries using a fast low angle shot readout at 3 Tesla

BACKGROUND

To evaluate ungated nonenhanced hybridized arterial spin labeling (hASL) magnetic resonance angiography (MRA) of the extracranial carotid arteries using a fast low angle shot (FLASH) readout at 3 Tesla.

METHODS

In this retrospective, institutional review board-approved and HIPAA-compliant study, we evaluated the image quality (4-point scale) of nonenhanced hASL MRA using a FLASH readout with respect to contrast-enhanced MRA (CEMRA) in 37 patients presenting with neurologic symptoms. Two certified neuroradiologists independently evaluated 407 arterial segments (11 per patient) for image quality. The presence of vascular pathology was determined by consensus reading. Gwet's AC1 was used to assess inter-rater agreement in image quality scores, and image quality scores were correlated with age and body mass index. Objective measurements of arterial lumen area and sharpness in the carotid arteries were compared to values obtained with CEMRA. Comparisons were also made with conventional nonenhanced 2D time-of-flight (TOF) MRA.

RESULTS

CEMRA provided the best image quality, while nonenhanced hASL FLASH MRA provided image quality that exceeded 2D TOF at the carotid bifurcation and in the internal and external carotid arteries. All nine vascular abnormalities of the carotid and intracranial arteries detected by CEMRA were depicted with hASL MRA, with no false positives. Inter-rater agreement of image quality scores was highest for CEMRA (AC1 = 0.87), followed by hASL (AC1 = 0.61) and TOF (AC1 = 0.43) (P < 0.001, all comparisons). With respect to CEMRA, agreement in cross-sectional lumen area was significantly better with hASL than TOF in the common carotid artery (intraclass correlation (ICC) = 0.90 versus 0.66; P < 0.05) and at the carotid bifurcation (ICC = 0.87 versus 0.54; P < 0.05). Nonenhanced hASL MRA provided superior arterial sharpness with respect to CEMRA and 2D TOF (P < 0.001).

CONCLUSION

Although inferior to CEMRA in terms of image quality and inter-rater agreement, hASL FLASH MRA offers an alternative to 2D TOF for the nonenhanced evaluation of the extracranial carotid arteries at 3 Tesla. Compared with 2D TOF, nonenhanced hASL FLASH MRA provides improved quantification of arterial cross-sectional area, vessel sharpness, inter-rater agreement and image quality.

Magnetic Resonance Imaging in Ischemic Stroke and Cerebral Venous Thrombosis

Imaging is indispensable in the evaluation of patients presenting with central nervous system emergencies. Although computed tomography (CT) is the mainstay of initial assessment and triage, magnetic resonance imaging (MRI) has become vital in expanding diagnostic capabilities, refining management strategies, and developing our understanding of disease processes. Ischemic stroke and cerebral venous thrombosis are 2 areas wherein MRI is actively revolutionizing patient care. Familiarity with the imaging manifestations of these 2 disease processes is crucial for any radiologist reading brain MR studies. In this review, the fundamentals of image interpretation will be addressed in-depth. Furthermore, advanced imaging techniques which are redefining the role of emergency MRI will be outlined, with a focus on the pathophysiological mechanisms that underlie image interpretation. In particular, emerging data surrounding the use of MR perfusion imaging in acute stroke management portend dramatic shifts in neurointerventional management. To this end, a review of the recent stroke literature will hopefully enhance the radiologist's role in both meaningful reporting and multidisciplinary teamwork.

Arterial spin labeled carotid MR angiography: A phantom study examining the impact of technical and hemodynamic factors

PURPOSE

To quantify the accuracy of three-dimensional (3D) radial arterial spin labeled (ASL) magnetic resonance angiography (MRA) using vascular models of carotid stenosis.

METHODS

Eight vascular models were imaged at 1.5 Tesla using pulsatile flow waveforms at rates found in the internal carotid arteries (100-400 mL/min). The impacts of the 3D ASL imaging readout (fast low angle shot (FLASH) versus balanced steady-state free precession (bSSFP)), ultrashort echo time imaging using a pointwise encoding time reduction with radial acquisition (PETRA), and model stenosis severity on the accuracy of vascular model display at the location of stenosis were quantified. Accuracy was computed vis-à-vis a reference bSSFP volume acquired under no flow. Comparisons were made with standard-of-care contrast-enhanced MRA (CEMRA) and Cartesian time-of-flight (TOF) MRA protocols.

RESULTS

For 50% and 70% stenoses, CEMRA was most accurate (respective accuracies of 81.7% and 78.6%), followed by ASL FLASH (75.7% and 71.8%), ASL PETRA (69.6% and 70.6%), 3D TOF (66.6% and 57.1%), ASL bSSFP (68.7% and 51.2%), and 2D TOF (65.1% and 50.6%).

CONCLUSION

Flow phantom imaging studies show that ASL MRA can improve the display of hemodynamically significant carotid arterial stenosis compared with TOF MRA, with FLASH and ultrashort echo time readouts being most accurate.

Management of extracranial carotid artery disease

Stroke is the third leading cause of death in developed nations. Up to 88% of strokes are ischemic in nature. Extracranial carotid artery atherosclerotic disease is the third leading cause of ischemic stroke in the general population and the second most common nontraumatic cause among adults younger than 45 years. This article provides comprehensive, evidence-based recommendations for the management of extracranial atherosclerotic disease, including imaging for screening and diagnosis, medical management, and interventional management.

Coronary artery disease in congenital single coronary artery in adults: A Dutch case series

AIM: To assess the current diagnostic and therapeutic management and the clinical implications of congenital single coronary artery (SCA) in adults.

METHODS: We identified 15 patients with a SCA detected from four Dutch angiography centers in the period between 2010 and 2013. Symptomatic patients who underwent routine diagnostic coronary angiography (CAG) for suspected coronary artery disease and who incidentally were found to have isolated SCA were analyzed.

RESULTS: Fifteen (7 females) with a mean age of 58.5 ± 13.78 years (range 43-86) had a SCA. Conventional CAG demonstrated congenital isolated SCA originating as a single ostium from the right sinus of Valsalva in 6 patients and originating from the left in 9 patients. Minimal to moderate coronary atherosclerotic changes were found in 4, and severe stenotic lesions in another 4 patients. Seven patients were free of coronary atherosclerosis. Runs of non-sustained ventricular tachycardia were documented in 2 patients, one of whom demonstrated transmural ischemic changes on presentation. Myocardial perfusion scintigraphic evidence of transmural myocardial ischemia was found in 1 patient due to kinking and squeezing of the SCA with an interarterial course between the aorta and pulmonary artery. Multi-slice computed tomography (MSCT) was helpful to delineate the course of the anomalous artery relative to the aorta and pulmonary artery. Percutaneous coronary intervention was successfully performed in 3 patients. Eight patients were managed medically. Arterial bypass graft was performed in 4 patients with the squeezed SCA.

CONCLUSION: SCA may be associated with transient transmural myocardial ischemia and aborted sudden death in the absence of coronary atherosclerosis. The availability and sophistication of MSCT facilitates the delineation of the course of a SCA. We present a Dutch case series and review of the literature.

When to consider cardiovascular magnetic resonance in patients undergoing transcatheter aortic valve replacement?

PURPOSE OF REVIEW

To discuss the relevant techniques as well as the recent evidence that enhance the understanding of the reader on the applications of cardiovascular magnetic resonance (CMR) in transcatheter aortic valve replacement (TAVR). With different cardiac imaging modalities available as well as the advent of TAVR, it is important to define when CMR can be helpful in the periprocedural evaluation.

RECENT FINDINGS

The topics of interest covered in this review are CMR evaluation of aortic stenosis/regurgitation, TAVR sizing, vascular measurements for access planning, postimplantation paravalvular regurgitation (PVR), and the potential role of delayed enhancement assessment in patients undergoing TAVR.

SUMMARY

CMR is a complementary modality in the assessment of TAVR candidates. The ability of CMR to assess the hemodynamic significance of aortic stenosis and other valvulopathies, as well as to assess accurately the left ventricular ejection fraction and vascular anatomy, makes this technique well rounded. The roles of delayed enhancement for myocardial scar in the evaluation of TAVR candidates and PVR assessment in the postimplant patient are promising, but still yet to be fully defined.

Positron emission tomography imaging of atherosclerosis

Atherosclerosis-related cardiovascular events are the leading causes of death in the industrialized world. Atherosclerosis develops insidiously and the initial manifestation is usually sudden cardiac death, stroke, or myocardial infarction. Molecular imaging is a valuable tool to identify the disease at an early stage before fatal manifestations occur. Among the various molecular imaging techniques, this review mainly focuses on positron emission tomography (PET) imaging of atherosclerosis. The targets and pathways that have been investigated to date for PET imaging of atherosclerosis include: glycolysis, cell membrane metabolism (phosphatidylcholine synthesis), integrin α_vβ_3, low density lipoprotein (LDL) receptors (LDLr), natriuretic peptide clearance receptors (NPCRs), fatty acid synthesis, vascular cell adhesion molecule-1 (VCAM-1), macrophages, platelets, etc. Many PET tracers have been investigated clinically for imaging of atherosclerosis. Early diagnosis of atherosclerotic lesions by PET imaging can help to prevent the premature death caused by atherosclerosis, and smooth translation of promising PET tracers into the clinic is critical to the benefit of patients.

'Go with the flow ': a review of methods and advancements in blood flow imaging

Physics has delivered extraordinary developments in almost every facet of modern life. From the humble thermometer and stethoscope to X-Ray, CT, MRI, ultrasound, PET and radiotherapy, our health has been transformed by these advances yielding both morphological and functional metrics. Recently high resolution label-free imaging of the microcirculation at clinically relevant depths has become available in the research domain. In this paper, we present a comprehensive review on current imaging techniques, state-of-the-art advancements and applications, and general perspectives on the prospects for these modalities in the clinical realm.

Steady-state equilibrium phase inversion recovery ON-resonant water suppression (IRON) MR angiography in conjunction with superparamagnetic nanoparticles. A robust technique for imaging within a wide range of contrast agent dosages

PURPOSE

To investigate the ability of inversion recovery ON-resonant water suppression (IRON) in conjunction with P904 (superparamagnetic nanoparticles which consisting of a maghemite core coated with a low-molecular-weight amino-alcohol derivative of glucose) to perform steady-state equilibrium phase MR angiography (MRA) over a wide dose range.

MATERIALS AND METHODS

Experiments were approved by the institutional animal care committee. Rabbits (n = 12) were imaged at baseline and serially after the administration of 10 incremental dosages of 0.57-5.7 mgFe/Kg P904. Conventional T1-weighted and IRON MRA were obtained on a clinical 1.5 Tesla (T) scanner to image the thoracic and abdominal aorta, and peripheral vessels. Contrast-to-noise ratios (CNR) and vessel sharpness were quantified.

RESULTS

Using IRON MRA, CNR and vessel sharpness progressively increased with incremental dosages of the contrast agent P904, exhibiting constantly higher contrast values than T1 -weighted MRA over a very wide range of contrast agent doses (CNR of 18.8 ± 5.6 for IRON versus 11.1 ± 2.8 for T1 -weighted MRA at 1.71 mgFe/kg, P = 0.02 and 19.8 ± 5.9 for IRON versus -0.8 ± 1.4 for T1-weighted MRA at 3.99 mgFe/kg, P = 0.0002). Similar results were obtained for vessel sharpness in peripheral vessels, (Vessel sharpness of 46.76 ± 6.48% for IRON versus 33.20 ± 3.53% for T1-weighted MRA at 1.71 mgFe/Kg, P = 0.002, and of 48.66 ± 5.50% for IRON versus 19.00 ± 7.41% for T1-weighted MRA at 3.99 mgFe/Kg, P = 0.003).

CONCLUSION

Our study suggests that quantitative CNR and vessel sharpness after the injection of P904 are consistently higher for IRON MRA when compared with conventional T1-weighted MRA. These findings apply for a wide range of contrast agent dosages.

MRI and MRA of Aortic Disease

Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) play a critical role in diagnosing aortic disease such as aortic dissection and aneurysm. Additionally, the advent of contrast-enhanced MRA has allowed MRA to advance markedly and several new imaging techniques to emerge as well. While computed tomography (CT) angiography using multidetector-row CT is a significant innovation, MRA may generate more useful diagnostic information, such as on the artery of Adamkiewicz.

Nonrigid registration of three-dimensional ultrasound and magnetic resonance images of the carotid arteries

Atherosclerosis at the carotid bifurcation can result in cerebral emboli, which in turn can block the blood supply to the brain causing ischemic strokes. Noninvasive imaging tools that better characterize arterial wall, and atherosclerotic plaque structure and composition may help to determine the factors which lead to the development of unstable lesions, and identify patients at risk of plaque disruption and stroke. Carotid magnetic resonance (MR) imaging allows for the characterization of carotid vessel wall and plaque composition, the characterization of normal and pathological arterial wall, the quantification of plaque size, and the detection of plaque integrity. On the other hand, various ultrasound (US) measurements have also been used to quantify atherosclerosis, carotid stenosis, intima-media thickness, total plaque volume, total plaque area, and vessel wall volume. Combining the complementary information provided by 3D MR and US carotid images may lead to a better understanding of the underlying compositional and textural factors that define plaque and wall vulnerability, which may lead to better and more effective stroke prevention strategies and patient management. Combining these images requires nonrigid registration to correct the nonlinear misalignments caused by relative twisting and bending in the neck due to different head positions during the two image acquisition sessions. The high degree of freedom and large number of parameters associated with existing nonrigid image registration methods causes several problems including unnatural plaque morphology alteration, high computational complexity, and low reliability. Thus, a "twisting and bending" model was used with only six parameters to model the normal movement of the neck for nonrigid registration. The registration technique was evaluated using 3D US and MR carotid images at two field strengths, 1.5 and 3.0 T, of the same subject acquired on the same day. The mean registration error between the segmented carotid artery wall boundaries in the target US image and the registered MR images was calculated using a distance-based error metric after applying a "twisting and bending" model based nonrigid registration algorithm. An average registration error of 1.4 +/- 0.3 mm was obtained for 1.5 T MR and 1.5 +/- 0.4 mm for 3.0 T MR, when registered with 3D US images using the nonrigid registration technique presented in this paper. Visual inspection of segmented vessel surfaces also showed a substantial improvement of alignment with this nonrigid registration technique compared to rigid registration.

MR imaging: influence of imaging technique and postprocessing on measurement of internal carotid artery stenosis

BACKGROUND AND PURPOSE

MR angiography (MRA) is increasingly used as an alternative to digital subtraction angiography (DSA) to evaluate internal carotid artery (ICA) stenosis. Because MRA is not standardized in data acquisition and postprocessing, we sought to evaluate the effects of different acquisition techniques (time-of-flight MRA [TOF-MRA]) and contrast-enhanced MRA [CE-MRA]) and postprocessing methods (maximum intensity projection [MIP], multiplanar reformation [MPR], and volume-rendering on stenosis grading.

MATERIALS AND METHODS

Fifty patients (33 men, 17 women) with symptomatic ICA stenosis were examined at 1.5T. Two imaging techniques and 3 postprocessing methods resulted in 6 image datasets per patient. Two readers independently evaluated ICA stenosis according to the North American Symptomatic Carotid Endarterectomy Trial criteria. Interobserver variability was calculated with the Pearson correlation coefficient and simultaneous confidence intervals (CI). The relationship of the values of ICA stenosis between the techniques was assessed by means of simultaneous 95% Tukey CI.

RESULTS

Interobserver agreement was high. Higher concordance was found for postprocessing techniques with TOF- than with CE-MRA; the mean difference between TOF-MPR and TOF-MIP was 0.4% (95% CI, -2.9%-3.8%). Stenosis values for CE-MPR differed significantly from those of CE volume-rendering (7.2%; 95% CI, 3.9%-10.6%).

CONCLUSION

Stenosis grading was found to be independent of the postprocessing technique except for comparison of CE-MPR with CE volume-rendering, with the volume-rendering technique resulting in higher stenosis values. MPR seems to be best-suited for measurement of ICA stenosis. Parameter setting is critical with volume-rendering, in which stenosis values were consistently higher compared with the other methods.

Isolated interrupted aortic arch, a rare cause of hypertension in adults

Interrupted aortic arch (IAA) is a rare and usually lethal congenital malformation. Patients with complete IAA very rarely do reach adult age without previous surgical intervention. The present report describes a 26-year-old asymptomatic isolated IAA case with hypertension that was incidentally diagnosed. IAA just distal to the left subclavian artery and a markedly developed collateral circulation was demonstrated by cardiac catheterization and thoracic 3D magnetic resonance angiography. This case report was also interesting that only mild arterial hypertension of the upper extremities was incidentally found in the patient.

Coronary artery anomalies and variants: technical feasibility of assessment with coronary MR angiography at 3 T

The purpose of this study was to prospectively use a whole-heart three-dimensional (3D) coronary magnetic resonance (MR) angiography technique specifically adapted for use at 3 T and a parallel imaging technique (sensitivity encoding) to evaluate coronary arterial anomalies and variants (CAAV). This HIPAA-compliant study was approved by the local institutional review board, and informed consent was obtained from all participants. Twenty-two participants (11 men, 11 women; age range, 18-62 years) were included. Ten participants were healthy volunteers, whereas 12 participants were patients suspected of having CAAV. Coronary MR angiography was performed with a 3-T MR imager. A 3D free-breathing navigator-gated and vector electrocardiographically-gated segmented k-space gradient-echo sequence with adiabatic T2 preparation pulse and parallel imaging (sensitivity encoding) was used. Whole-heart acquisitions (repetition time msec/echo time msec, 4/1.35; 20 degrees flip angle; 1 x 1 x 2-mm acquired voxel size) lasted 10-12 minutes. Mean examination time was 41 minutes +/- 14 (standard deviation). Findings included aneurysms, ectasia, arteriovenous fistulas, and anomalous origins. The 3D whole-heart acquisitions developed for use with 3 T are feasible for use in the assessment of CAAV.

Magnetic resonance angiographic assessment of upper extremity vessels prior to vascular access surgery: feasibility and accuracy

A contrast-enhanced magnetic resonance angiography (CE-MRA) protocol for selective imaging of the entire upper extremity arterial and venous tree in a single exam has been developed. Twenty-five end-stage renal disease (ESRD) patients underwent CE-MRA and duplex ultrasonography (DUS) of the upper extremity prior to hemodialysis vascular access creation. Accuracy of CE-MRA arterial and venous diameter measurements were compared with DUS and intraoperative (IO) diameter measurements, the standard of reference. Upper extremity vasculature depiction was feasible with CE-MRA. CE-MRA forearm and upper arm arterial diameters were 2.94 +/- 0.67 mm and 4.05 +/- 0.84 mm, respectively. DUS arterial diameters were 2.80 +/- 0.48 mm and 4.38 +/- 1.24 mm; IO diameters were 3.00 +/- 0.35 mm and 3.55 +/- 0.51 mm. Forearm arterial diameters were accurately determined with both techniques. Both techniques overestimated upper arm arterial diameters significantly. Venous diameters were accurately determined with CE-MRA but not with DUS (forearm: CE-MRA: 2.64 +/- 0.61 mm; DUS: 2.50 +/- 0.44 mm, and IO: 3.40 +/- 0.22 mm; upper arm: CE-MRA: 4.09 +/- 0.71 mm; DUS: 3.02 +/- 1.65 mm, and IO: 4.30 +/- 0.78 mm). CE-MRA enables selective imaging of upper extremity vasculature in patients requiring hemodialysis access. Forearm arterial diameters can be assessed accurately by CE-MRA. Both CE-MRA and DUS slightly overestimate upper arm arterial diameters. In comparison to DUS, CE-MRA enables a more accurate determination of upper extremity venous diameters.

Multidetector-row CT angiography in the study of atherosclerotic carotid arteries

Pathologies of the carotid arteries, and in particular atherosclerosis, are now an important medical problem. Stroke is the third leading cause of severe disability in the Western World leading to millions of deaths every year. Extracranial carotid atherosclerotic disease is the major risk factor for stroke. In years, with the advent of multidetector-row CT (MDCT) scanners and the use of specific angiographic protocols (MDCTA), CT imaging of the carotid arteries has become increasingly effective. In addition, the volume data obtained can be further rendered to generate high-quality two-dimensional and three-dimensional images. The purpose of this study was to review the atherosclerotic carotid arteries, their complications and how MDCTA depicts them, underlining the benefits and pitfalls of this diagnostic technique.

Cardiac MRI in ischemic heart disease with severe coronary artery stenosis

RATIONALE AND OBJECTIVES

The aim was to evaluate the left ventricular wall motion abnormalities, perfusion and late contrast enhancement patterns on magnetic resonance imaging (MRI) in patients with 70% or higher degree stenosis or occlusion of coronary arteries on coronary angiography.

MATERIALS AND METHODS

Twenty-four patients (5 women, 19 men, age range 38-78, mean age 59.1) who had 70% or higher degree stenosis or occlusion of coronary arteries on coronary angiography who had been referred for cardiac MRI were included. On coronary angiography, 20 vessels were totally occluded [left anterior descending artery (LAD) 12; left circumflex coronary artery (LCx) 2; right coronary artery 6] and 20 vessels were severely stenotic (70-99%). In 5 patients' three vessels, in 6 patients' two vessels, and in 13 patients' a single vessel was involved. Wall motion, perfusion abnormalities, and late contrast enhancement consistent with nonviable myocardium were analyzed at apical, at midventricular, and basal levels on short-axis images of cardiac MRI in concordance with the segmental irrigation areas of the coronary arteries.

RESULTS

Impaired perfusion was observed on the corresponding irrigation segments of 39 vessels of 40 coronary artery branches. Wall motion abnormalities were present on corresponding irrigation areas of 30 severely stenotic vessels. Combined evaluation of wall motion and perfusion, segments with the decreased left ventricular contraction, and perfusion matched with the corresponding irrigation areas of all of the 40 stenotic or occluded vessels.

CONCLUSION

A correlation was found between the combined assessments of myocardial perfusion, wall motion, and viability on late contrast enhancement on cardiac MRI with the clinical and angiography findings. Thus this combined MRI protocol can be used for the evaluation of ischemic heart disease.

Analysis of the lesion distributions and mechanism of acute middle cerebral artery infarctions involving the striatocapsular region

BACKGROUND AND PURPOSE

There is no clear description about the patterns of each mechanism of striatocapsular infarctions. The aims of our study were to elucidate differences in the distributions of lesions of acute middle cerebral artery (MCA) infarctions involving the striatocapsular region and to compare those following embolic striatocapsular infarctions with those originating from MCA disease.

METHODS

We prospectively enrolled patients with acute infarcts located in the lenticulostriate artery territory that were not lacunar infarcts. Brain coronal diffusion-weighted imaging (DWI) was obtained and magnetic resonance angiography (MRA) was carried out to evaluate the distribution of infarct lesions and MCA stenosis in all patients. The types of infarct distribution were divided into three categories: (1) dominant in the distal territory (DD), (2) distributed equally between the distal and proximal territories (DE), and (3) dominant in the proximal territory. We performed tests for embolic sources (transthoracic echocardiography, transesophageal echocardiography, Holter monitoring, and contrast-enhanced MRA including the aortic arch) in most patients. Stroke mechanisms were classified into stroke from proximal embolism, MCA disease, and stroke of undetermined etiology.

RESULTS

A total of 47 patients (28 men and 19 women; mean age, 62 years) were recruited. A proximal embolic source was significantly more prevalent in patients with a DE lesion than in those with a DD lesion. The most common proximal embolic source was of cardiac origin. In contrast, symptomatic MCA stenoses were more common in patients with a DD lesion than in those with a DE lesion.

CONCLUSIONS

These results suggest that the dominant area of striatocapsular infarction on coronal DWI is an important clue for stroke etiology. Coronal DWI could therefore be helpful to determining the mechanisms in patients with striatocapsular infarctions that are currently described as having an "undetermined etiology" according to the Trial of Org 10172 in Acute Stroke Treatment classification.

Gadolinium-Enhanced 3D MR Angiography of Pulmonary Hypoplasia and Aplasia

OBJECTIVE

The goal of this study was to determine the role of gadolinium-enhanced 3D MR angiography (MRA) in patients with suspected pulmonary hypoplasia and aplasia in a retrospective analysis of MRA and digital subtraction angiography in 11 patients with clinical and/or radiologic suspicion of pulmonary hypoplasia and aplasia.

CONCLUSION

Gadolinium-enhanced 3D MRA is capable of diagnosing pulmonary hypoplasia and aplasia rapidly and accurately. Both pulmonary hypoplasia and aplasia can be shown morphologically in a noninvasive manner, obviating digital subtraction angiography.

Non-invasive methods and stimuli for evaluating the skin's microcirculation

Vessels in the skin are arranged into superficial and deep horizontal plexuses and they are involved in thermoregulation, oxygen and nutritional support. The skin has a large number of functions and broad appeal spanning basic mechanistic and clinical research. Indeed, the skin can be used as a marker of normal and impaired vascular control and, owing to its accessibility and frequent involvement, is easy to investigate non-invasively. A large number of non-invasive methods are available for investigating the skin, ranging from those that permit the visualisation of microvessels, to those that monitor blood flow or one of its derivatives (e.g., skin temperature and transcutaneous oxygen). Such methods can be combined with non-invasive, dynamic stimuli (e.g., the use of cold or warm stimuli, activation of the peripheral nervous system or local neuronal systems, and the topical application of vasoactive drugs) and this potentially enables the differentiation of underlying disorders (e.g., primary from secondary Raynaud's phenomenon) and also to quantify changes over time or following intervention. The present article outlines the non-invasive methods and dynamic tests that can be used to investigate the microcirculation of the skin.

Evaluation of coronary arterial stenoses using 2D magnetic resonance coronary angiography

This study investigated the usefulness and limitations of magnetic resonance coronary angiography (MRCA). MRCA was performed with an electrocardiographically gated gradient echo sequence with k-space segmentation. Coronary angiography (CAG) was performed using a conventional system. We had three protocols. In protocol one, 160 consecutive patients (279 coronary arteries) who underwent initial CAG for diagnosing coronary artery disease were enrolled. Out of the 279 coronary arteries, 235 arteries (84.2%) were visualised with an image quality suitable for further analysis. In these 235 arteries, the validity for diagnosing over 75% arterial stenosis was 98%, and sensitivity and specificity was 79%. In protocol two, 48 stenoses were evaluated for restenosis after balloon angioplasty. The validity for diagnosing restenosis by MRCA was 93% in sensitivity and 33% in specificity. In protocol three, comprising 18 coronary arteries with total obstruction, the presence of collaterals was evaluated. The development of collateral circulation improved MRCA findings in the distal portion of obstructed coronary arteries. We conclude that MRCA provides useful information with acceptable sensitivity and specificity before balloon angioplasty. However, MRCA has a tendency to over-estimate restenosis after balloon angioplasty.

Anomalous origin of right coronary artery: Magnetic resonance angiography and viability study

OBJECTIVE

To detect origin and course and to evaluate viability in patients with anomalous RCA.

DESIGN

3D coronary MR angiography and viability study using gadolinium-enhanced magnetic resonance imaging (Gd-MRI) was performed.

SETTING

A tertiary hospital center.

PATIENTS

Four patients, selected from the catheter lab, were studied.

RESULTS

Anomalous RCA from the left sinus of Valsalva was identified in all patients. Inferior myocardial infarction was documented in three patients.

CONCLUSIONS

Magnetic resonance imaging can non-invasively identify anomalous RCA and perform viability study in the same examination.

Growth hormone treatment and aortic dimensions in Turner syndrome

BACKGROUND

In recent years many girls with Turner syndrome (TS) have been treated with supraphysiological doses of GH to increase adult height. In addition to promoting statural growth, GH may have direct effects on the cardiovascular system.

OBJECTIVE

We sought to determine whether GH treatment affects aortic diameter in girls with TS because there is an increased risk for aortic dilation and dissection in this syndrome.

METHODS

In a retrospective, cross-sectional study, we compared ascending and descending aortic diameters measured by magnetic resonance imaging in GH-treated (n = 53) vs. untreated (n = 48) patients with TS participating in a National Institutes of Health protocol between 2001 and 2004.

RESULTS

The average duration of GH treatment was 4.7 with se 0.4 yr (range 2-11 yr). The two groups were similar in age and weight, but GH-treated subjects were on average 8 cm taller (P = 0.002). The diameter of the ascending aorta was increased by 7.3% and descending aorta by 8.9% in the GH-treated group. However, after correction for age, height, weight, and presence of bicuspid aortic valve and coarctation, using a multiple regression, neither history of GH treatment nor the length of GH treatment had an effect on the aortic diameter. Weight (P = 0.02), height (P = 0.001), and presence of bicuspid aortic valve (P = 0.0001) were associated with larger ascending aortic diameter, whereas age (P = 0.008), height (P = 0.02), and history of coarctation (P = 0.006) were associated with larger descending aortic diameter.

CONCLUSIONS

GH treatment of girls with TS does not seem to affect ascending or descending aortic diameter above the increase related to the larger body size.

Magnetic resonance studies of brain lesions in patients with Kawasaki disease

We evaluated brain lesions in patients with coronary arterial lesions (CAL) as a complication of Kawasaki disease (KD) by magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). Among 47 patients who underwent coronary angiography for the evaluation of CAL due to KD at Kyushu University Hospital from April 1996 to September 2004, 24 patients were evaluated prospectively by brain MRI and MRA 0.1-21.2 years after the onset of KD. Although most patients had irritability or lethargy, none of them had significant neurological symptoms or signs during the acute phase, except one who showed neck stiffness. In one patient with no apparent neurological symptoms out of the 24 patients, brain MRI and MRA revealed right cerebellar infarction and obliteration of the right posterior inferior cerebellar artery, respectively. These results revealed the presence of cerebrovascular lesion in one of the 24 KD patients with CAL and suggested the need to consider the possibility of brain lesions in severe cases of KD with or without neurological symptoms.

Diagnosis of abdominal aortic hypoplasia by state-of-the-art MR angiography

Abdominal aortic hypoplasia is a rare vascular variant with possible major clinical sequelae when the renal arteries are also involved. The condition is thought to result from embryonic overfusion of the two dorsal aortas. The diagnosis may be considered in patients presenting with hypertension in the neonatal period and severely reduced or absent arterial pulses in the groin. We present contrast-enhanced state-of-the-art magnetic resonance angiography imaging findings in an 8-year-old boy with abdominal aortic hypoplasia.

A Case of Mistaken Identity: Intraoperative Discovery of an Extracranial Internal Carotid Artery Aneurysm

The optimal diagnostic modality for extracranial carotid artery aneurysm is not firmly established because of the emerging trend of replacing traditional carotid angiography with magnetic resonance imaging and angiography. An extracranial carotid artery aneurysm can have profound neurologic sequelae, and an elective resection is often suggested. Imaging studies should firmly establish the diagnosis and differentiate the aneurysm from other lesions of the carotid, especially carotid body tumor, prior to surgical planning. Magnetic resonance studies may not properly distinguish between different lesions of the carotid arteries. This case of an unexpected carotid aneurysm found intraoperatively demonstrates that while traditional angiography is costly and invasive, it is still the diagnostic study of choice when an aneurysm is a possible diagnosis.