Whole-body magnetic resonance angiography of patients using a standard clinical scanner

Systemic arteriosclerosis is associated with left ventricular remodeling but not atherosclerosis: a TASCFORCE study

BACKGROUND

Arteriosclerosis (arterial stiffening) is associated with future cardiovascular events, with this effect postulated to be due to its effect on cardiac afterload, atherosclerosis (plaque formation) progression or both, but with limited evidence examining these early in disease formation. The aim of the current study is to examine the association between arteriosclerosis, atherosclerosis and ventricular remodelling in a population at low-intermediate cardiovascular risk.

METHODS

One thousand six hundred fifty-one subjects free of clinical cardiovascular disease and with a < 20% 10 year cardiovascular risk score underwent a cardiovascular magnetic resonance (CMR) study and whole body CMR angiogram. Arteriosclerosis was measured using total arterial compliance (TAC) - calculated as the indexed stroke volume divided by the pulse pressure. Atherosclerosis was quantified using a standardised atheroma score (SAS) which was calculated by scoring 30 arterial segments within the body based on the degree of stenosis, summating these scores and normalising it to the number of assessable segments. Left ventricular remodelling was measured using left ventricular mass to volume ratio (LVMVR).

RESULTS

One thousand five hundred fifteen (38% male, 53.8 ± 8.2 years old) completed the study. On univariate analysis TAC was associated with SAS but this was lost after accounting for cardiovascular risk factors in both males (B = - 0.001 (- 0.004-0.002),p = 0.62) and females (B = 0.000(95%CI -0.002--0.002),p = 0.78). In contrast compliance correlated with LVMVR after accounting for cardiovascular risk factors (B = - 0.12(95%CI -0.16--0.091),p < 0.001 in males; B = - 0.12(95%CI -0.15--0.086),p < 0.001 in females).

CONCLUSION

Systemic arteriosclerosis is associated with left ventricular remodelling but not atherosclerosis. Future efforts in cardiovascular risk prevention should thus seek to address both arteriosclerosis and atherosclerosis individually.

Whole-body magnetic resonance imaging in children: state of the art

Whole-body imaging in children was classically performed with radiography, positron-emission tomography, either combined or not with computed tomography, the latter with the disadvantage of exposure to ionizing radiation. Whole-body magnetic resonance imaging (MRI), in association with the recently developed metabolic and functional techniques such as diffusion-weighted imaging, has brought the advantage of a comprehensive evaluation of pediatric patients without the risks inherent to ionizing radiation usually present in other conventional imaging methods. It is a rapid and sensitive method, particularly in pediatrics, for detecting and monitoring multifocal lesions in the body as a whole. In pediatrics, it is utilized for both oncologic and non-oncologic indications such as screening and diagnosis of tumors in patients with genetic syndromes, evaluation of disease extent and staging, evaluation of therapeutic response and post-therapy follow-up, evaluation of non neoplastic diseases such as multifocal osteomyelitis, vascular malformations and syndromes affecting multiple regions of the body. The present review was aimed at describing the major indications of whole-body MRI in pediatrics added of technical considerations.

Technical assessment of whole body angiography and cardiac function within a single MRI examination

AIM

To evaluate a combined protocol for simultaneous cardiac MRI (CMR) and contrast-enhanced (CE) whole-body MR angiography (WB-MRA) techniques within a single examination.

MATERIALS AND METHODS

Asymptomatic volunteers (n = 48) with low-moderate risk of cardiovascular disease (CVD) were recruited. The protocol was divided into four sections: (1) CMR of left ventricle (LV) structure and function; (2) CE-MRA of the head, neck, and thorax followed by the distal lower limbs; (3) CMR LV "late gadolinium enhancement" assessment; and (4) CE-MRA of the abdomen and pelvis followed by the proximal lower limbs. Multiple observers undertook the image analysis.

RESULTS

For CMR, the mean ejection fraction (EF) was 67.3 ± 4.8% and mean left ventricular mass (LVM) was 100.3 ± 22.8 g. The intra-observer repeatability for EF ranged from 2.1-4.7% and from 9-12 g for LVM. Interobserver repeatability was 8.1% for EF and 19.1 g for LVM. No LV delayed myocardial enhancement was observed. For WB-MRA, some degree of luminal narrowing or stenosis was seen at 3.6% of the vessel segments (involving n = 29 of 48 volunteers) and interobserver radiological opinion was consistent in 96.7% of 1488 vessel segments assessed.

CONCLUSION

Combined assessment of WB-MRA and CMR can be undertaken within a single examination on a clinical MRI system. The associated analysis techniques are repeatable and may be suitable for larger-scale cardiovascular MRI studies.

The relationship between carotid intima-media thickness and global atherosclerosis

Background

The aim of this study was to investigate the relationship between (i) carotid intima–media thickness (CIMT) at baseline as well as (ii) change in CIMT over 5 years (ΔCIMT) and atherosclerotically induced luminal narrowing in non-coronary arterial territories assessed by whole-body magnetic resonance angiography (WBMRA).

Methods and results

In subgroups of the Prospective Investigation of Vasculature in Uppsala Seniors (PIVUS) study, US measurements of CIMT in the common carotid arteries were analysed at 70 and 75 years and ΔCIMT was calculated (n = 272). WBMRA, assessing arterial stenosis in five different territories by which also a total atherosclerotic score (TAS) was calculated, was performed at 70 years (n = 306).

Results

Carotid intima–media thickness in the carotid artery at baseline was correlated with TAS (P = 0·0001) when adjusted to a set of traditional risk factors for atherosclerosis, as well as to stenosis in two of the different investigated territories (aorta and lower leg, P = 0·013 and P = 0·004), but there was no significant correlation between ΔCIMT and TAS (P = 0·41).

Conclusions

In the present study, CIMT, but not ΔCIMT over 5 years, in the carotid artery was related to overall stenoses in the body, as assessed by WBMRA. These findings support CIMT as a general marker for atherosclerosis.

Total atherosclerotic burden by whole body magnetic resonance angiography predicts major adverse cardiovascular events

OBJECTIVE

The purpose of the present study was to investigate the relationship between the Total Atherosclerotic Score (TAS), a measurement of the overall atherosclerotic burden of the arterial tree by whole body magnetic resonance angiography (WBMRA), and the risk of major adverse cardiovascular events (MACE), defined as cardiac death, myocardial infarction, stroke and/or coronary revascularization, assuming that TAS predicts MACE.

METHODS AND RESULTS

305 randomly selected 70 year-old subjects (47% women) underwent WBMRA. Their atherosclerotic burden was evaluated and TAS > 0, that is atherosclerotic changes, were found in 68% of subjects. During follow-up (mean 4.8 years), MACE occurred in 25 subjects (8.2%). Adjusting for multiple risk factors, TAS was associated with MACE (OR 8.86 for any degree of vessel lumen abnormality, 95%CI 1.14-69.11, p = 0.037). In addition, TAS improved discrimination and reclassification when added to the Framingham risk score (FRS), and ROC (Receiver Operator Curve) increased from 0.681 to 0.750 (p = 0.0421).

CONCLUSION

In a population-based sample of 70 year old men and women WBMRA, with TAS, predicted MACE independently of major cardiovascular risk factors.

Comparison of whole body MR angiography at 1.5 and 3 Tesla in patients with hereditary hyperlipidemia

BACKGROUND

Patients suffering from hereditary hyperlipidemia have a high risk for premature cardiovascular disease and death as a consequence of accelerated atherosclerosis.

PURPOSE

To prospectively and intra-individually compare image quality and detectability of stenoses in contrast enhanced whole-body MRA (WBMRA) at 1.5 and 3 Tesla (T) in patients with hereditary hyperlipidemia.

MATERIAL AND METHODS

Twenty-seven patients with hereditary hyperlipidemia received a 1.5 and 3 T gadopentetate dimeglumine contrast-enhanced WBMRA. Twenty-three defined arterial segments were analyzed regarding depiction of target vessels and image quality according to a 5-point-scale ('not evaluable' to 'excellent'). Wilcoxon matched pair test was performed for comparison. Forty-three defined arterial segments were analyzed for the degree of stenosis (0%, 1-49%, 50-99% and 100%) as well as vessel alterations such as aneurysms. Chi-square test was performed for comparison.

RESULTS

1.5 T and 3 T scans yielded WBMRA with diagnostic quality in all patients. In seven of 23 arterial segments (30.4%) image quality was rated significantly higher at 3 T, whereas there was no significant difference in the remaining 16 segments between WBMRA at 1.5 T and 3 T. All relevant stenoses (n = 5), occlusions (n = 6), and aneurysms (n = 3) were evaluated similarly at both field strengths.

CONCLUSION

WBMRA can be performed at 1.5 T and 3 T with diagnostic image quality. Image quality was significantly higher at 3 T than at 1.5 T in only 30.4% of the arterial segments. In order to effectively take advantage of the higher field strength, further optimization of sequence parameters and injection protocols for WBMRA at 3 T is necessary.

Whole-body magnetic resonance angiography for presurgical planning of free-flap head and neck reconstruction

OBJECTIVES

Aim of the study was to evaluate if a whole-body magnetic resonance angiography (MRA) protocol meets the requirements to evaluate the donor and host site target vessels for planning of microvascular head and neck reconstructions.

PATIENTS AND METHODS

In 20 patients, scheduled for reconstruction of the mandible with fibular free flaps, contrast-enhanced whole-body MRA was performed prior to surgery. 32-Channel 1.5-T MR angiograms were acquired using a 2-step contrast (gadobutrol) injection scheme to visualize the arterial vasculature from head to feet. Maximum intensity projection and multiplanar reconstruction technique was employed to visualize MRA data. For image evaluation the arterial tree was divided into 51 segments. The presence of artefacts impairing diagnostic quality was noted. Evaluable segments were assessed regarding the presence of stenoses >50% diameter reduction, occlusions or aneurysms.

RESULTS

No adverse reactions or complications occurred. Of 1020 vessel segments 1003 (98.3%) were evaluable. 36 stenoses >50%, 50 occlusions and one aneurysm were observed. In 21 of 40 lower limbs relevant atherosclerotic changes were depicted.

CONCLUSION

Whole-body MRA proved to be a suitable three-dimensional, noninvasive, nonionising modality for preoperative evaluation of the entire arterial vasculature.

Sensitivity and specificity of the ankle—brachial index to diagnose peripheral artery disease: a structured review

The ankle—brachial index (ABI) is a simple, inexpensive diagnostic test for peripheral artery disease (PAD). However, it has shown variable accuracy for identification of significant stenosis. The authors performed a structured review of the sensitivity and specificity of ABI ≤ 0.90 for the diagnosis of PAD. MEDLINE, EMBASE, Cochrane databases, Science Citation Index database, and Biological Abstracts database were searched for studies of the sensitivity and specificity of using ABI ≤ 0.90 for the diagnosis of PAD. Eight studies comprising 2043 patients (or limbs) met the inclusion criteria. The result indicated that, although strict inclusion criteria on studies were formulated, different reference standards were found in these studies, and methods of ABI determination and characteristics of populations varied greatly. A high level of specificity (83.3—99.0%) and accuracy (72.1—89.2%) was reported for an ABI ≤ 0.90 in detecting ≥ 50% stenosis, but there were different levels of sensitivity (15—79%). Sensitivity was low, especially in elderly individuals and patients with diabetes. In conclusion, the test of ABI ≤ 0.90 can be a simple and useful tool to identify PAD with serious stenosis, and may be substituted for other non-invasive tests in clinical practice.

Prediction of coronary artery disease by a systemic atherosclerosis score index derived from whole-body MR angiography

BACKGROUND

Whole-body magnetic resonance angiography (WB-MRA) has shown its potential for the non-invasive assessment of nearly the entire arterial vasculature within one examination. Since the presence of extra-cardiac atherosclerosis is associated with an increased risk of coronary events, our goal was to establish the relationship between WB-MRA findings, including a systemic atherosclerosis score index, and the presence of significant coronary artery disease (CAD).

METHODS

WB-MRA was performed on a 1.5T scanner in 50 patients scheduled to undergo elective cardiac catheterization for suspected CAD. In each patient, 40 extra-cardiac vessel segments were evaluated and assigned scores according to their luminal narrowing. The atherosclerosis score index (ASI) was generated as the ratio of summed scores to analyzable segments.

RESULTS

ASI was higher in patients with significant (> 50% stenosis) CAD (n = 27) vs. patients without CAD (n = 22; 1.56 vs. 1.28, p = 0.004). ASI correlated with PROCAM (R = 0.57, p < 0.001) and Framingham (R = 0.36, p = 0.01) risk scores as estimates of the 10-year risk of coronary events. A ROC derived ASI of > 1.54 predicted significant CAD with a sensitivity of 59%, specificity of 86% and a positive predictive value of 84%. Logistic regression revealed ASI > 1.54 as the strongest independent predictor for CAD with a 11-fold increase in likelihood to suffer from significant coronary disease. On the contrary, while 15/27 (55%) of patients with CAD exhibited at least one extra-cardiac stenosis > 50%, only 3/22 (14%) of those patients without CAD did (p = 0.003). The likelihood for an extra-cardiac stenosis when CAD is present differed between vascular territories and ranged from 15% for a carotid stenosis to 44% for a stenosis in the lower extremities.

CONCLUSION

This study provides important new evidence for the close association of extra-cardiac and coronary atherosclerosis. The novel findings that a WB-MRA derived systemic atherosclerosis score index is not only associated with established cardiovascular risk scores but is also predictive of significant CAD suggest its potential prognostic implications and underline the importance to screen for coronary disease in patients with extra-cardiac manifestations of atherosclerosis.

Whole-body MR angiography with body coil acquisition at 3 T in patients with peripheral arterial disease using the contrast agent gadofosveset trisodium

RATIONALE AND OBJECTIVES

Whole-body magnetic resonance angiography (WB-MRA) at 3 T with body coil acquisition has not previously been investigated. In this study, WB-MRA was performed in this manner using the blood pool contrast agent gadofosveset trisodium.

MATERIALS AND METHODS

Eleven consecutive patients (five men, six women) with symptomatic peripheral arterial disease (two with critical limb ischemia, nine with claudication) were examined. Conventional digital subtraction angiography (DSA) of the aorta and the inflow and runoff arteries was used as the reference method. WB-MRA was performed using four slightly overlapping stations covering the arteries from the neck to the ankles. The arterial system was divided into 42 segments that were analyzed for the presence of significant arterial disease (> or =50% luminal narrowing or occlusion) by two blinded observers.

RESULTS

Sensitivities for detecting a significant arterial lesion with WB-MRA using gadofosveset as the contrast agent were 0.66 (95% confidence interval [CI], 0.49-0.79) and 0.68 (95% CI, 0.52-0.81) for the two observers. Specificities were 0.82 (95% CI, 0.74-0.88) and 0.93 (95% CI, 0.87-0.96), respectively. Intermodality agreement between WB-MRA and DSA was moderate to good, with overall kappa values of 0.44 (95% CI, 0.29-0.59) and 0.63 (95% CI, 0.5-0.77) for the two observers. Interobserver agreement for WB-MRA was good, at kappa = 0.60 (95% CI, 0.50-0.71).

CONCLUSION

WB-MRA at 3 T with body coil acquisition in patients with peripheral arterial disease showed good reproducibility but only moderate to good agreement with DSA. Further assessment of the method's clinical application is warranted.

Lower extremity artery stenosis distribution in an unselected elderly population and its relation to a reduced ankle-brachial index

OBJECTIVE

This study evaluated the distribution and degree of symmetry of lower extremity artery stenoses in an unselected elderly population and its relation to a reduced ankle-brachial index (ABI) measurement.

METHODS

This was a population-based study set in a university hospital comprising 306 randomly selected 70-year-old individuals participating in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Whole-body magnetic resonance angiography (MRA) and bilateral ABI measurements were performed in each participant. The prevalence of stenosis >or=50% was evaluated in nine different arterial segments in both legs: common iliac artery (CIA), external iliac artery (EIA), common femoral artery (CFA), superficial femoral artery (SFA), popliteal artery (PA), tibioperoneal trunk (TPTr), anterior tibial artery (ATA), posterior tibial artery (PTA), and peroneal artery. The relations between the prevalences of stenosis in different arterial segments in the right and left leg were assessed. An evaluation was made of the relation between a >or=50% stenosis and an ABI <0.9 in the different segments.

RESULTS

The prevalence of stenosis was 0% to 21%. In all segments, a stenosis was more commonly found in one of the legs only than in both legs. The prevalence of >or=50% stenosis in the right leg only, left leg only, and both legs was 0.3%, 0.7%, and 0% in the CIA; 0.3%, 1.0%, and 0.7% in the EIA; 0%, 0%, and 0% in the CFA; 2.0%, 1.3%, and 0.7% in the SFA; 0.7%, 0.7%, and 0.3% in the PA; 1.0%, 0.7%, and 0% in the TPTr; 5.6%, 6.3%, and 8.6% in the ATA; 0.7%, 1.7%, and 0% in the peroneal artery; and in 2.0%, 2.7%, and 3.4% in the PTA. When the legs were compared, a significant correlation was found for the presence of a >or=50% stenosis in the EIA, SFA, PA, ATA, and PTA. Seventeen participants showed ABI <0.9. In logistic regression analysis with ABI <0.9 as dependent variable, stenosis in SFA, ATA, and PTA were the major independent variables to explain a low ABI in both of the legs.

CONCLUSIONS

The distribution of stenosis differs substantially when legs are compared. Despite this difference, stenosis in SFA, ATA, and PTA was the major determinant of a low ABI in both of the legs.

Whole body MR imaging in diabetes

Diabetes mellitus is a major cardiovascular risk factor and one of the major causes for morbidity and mortality worldwide. Diabetic complications have not only major impact on the quality of life of diabetic patients, but are also potentially life-threatening. Therefore prevention, diagnosis and therapy of these long-term complications are of high importance. However, diagnosis of the variety of complications from diabetes mellitus remains a diagnostic challenge and usually several diagnostic steps are necessary to diagnose or exclude these complications. In the last years whole body magnetic resonance imaging (WB-MRI) including whole body magnetic resonance angiography (WB-MRA) has been introduced for cardiovascular imaging and is now increasingly applied in clinical routine for the workup of patients with cardiovascular disease and for cardiovascular screening. The article summarizes rationales for WB-MRI in diabetes mellitus, technical concepts of disease specific cardiovascular WB-MRI in diabetes mellitus and discusses potential clinical consequences.

Relationship between circulating FGF23 and total body atherosclerosis in the community

BACKGROUND

Fibroblast growth factor-23 (FGF23) is a regulator of mineral metabolism and has been suggested to play a role in vascular calcification in chronic kidney disease (CKD). Data on the association between FGF23 and atherosclerosis, both in CKD and in the community, is limited.

METHODS

The total body atherosclerosis score (AS) was determined by a magnetic resonance imaging-based angiography in 306 elderly men and women, representing a subsample of the community-based PIVUS cohort. Subjects were divided into three categories based on AS: AS = 0, low AS and high AS. Serum FGF23 was measured using a two-site monoclonal antibody ELISA.

RESULTS

In continuous and multi-category regression models, higher FGF23 was associated with a significant increase in the odds of having a high AS (OR 1.43, CI 1.06-1.92 to OR 3.01, CI 1.52-5.99). This association was stronger in individuals with eGFR <60 mL/min/1.73 m(2) (n = 27), reaching a nearly 6-fold increase in the odds for a high AS in the upper FGF23 tertile (OR 5.64, CI 2.78-11.5). We found weaker support for a relationship between FGF23 and the presence of atherosclerosis as subjects in the highest FGF23 tertile had an increased risk for an AS > 0 in crude models (OR 1.93, CI 1.05-3.55), but this was not statistically significant in adjusted (OR 1.42, CI 0.74-1.72) models.

CONCLUSIONS

We provide novel evidence supporting an association between serum FGF23 and total body atherosclerosis in the community. Additional studies are warranted to determine the prospective relationship between FGF23 and atherosclerosis, and whether FGF23 is a modifiable cardiovascular risk factor.

Whole-body magnetic resonance angiography at 3 tesla using a hybrid protocol in patients with peripheral arterial disease

The purpose of this study was to determine the diagnostic performance of 3T whole-body magnetic resonance angiography (WB-MRA) using a hybrid protocol in comparison with a standard protocol in patients with peripheral arterial disease (PAD). In 26 consecutive patients with PAD two different protocols were used for WB-MRA: a standard sequential protocol (n = 13) and a hybrid protocol (n = 13). WB-MRA was performed using a gradient echo sequence, body coil for signal reception, and gadoterate meglumine as contrast agent (0.3 mmol/kg body weight). Two blinded observers evaluated all WB-MRA examinations with regard to presence of stenoses, as well as diagnostic quality and degree of venous contamination in each of the four stations used in WB-MRA. Digital subtraction angiography served as the method of reference. Sensitivity for detecting significant arterial disease (luminal narrowing > or = 50%) using standard-protocol WB-MRA for the two observers was 0.63 (95%CI: 0.51-0.73) and 0.66 (0.58-0.78). Specificities were 0.94 (0.91-0.97) and 0.96 (0.92-0.98), respectively. In the hybrid protocol WB-MRA sensitivities were 0.75 (0.64-0.84) and 0.70 (0.58-0.8), respectively. Specificities were 0.93 (0.88-0.96) and 0.95 (0.91-0.97). Interobserver agreement was good using both the standard and the hybrid protocol, with kappa = 0.62 (0.44-0.67) and kappa = 0.70 (0.59-0.79), respectively. WB-MRA quality scores were significantly higher in the lower leg using the hybrid protocol compared to standard protocol (p = 0.003 and p = 0.03, observers 1 and 2). Distal venous contamination scores were significantly lower with the hybrid protocol (p = 0.02 and p = 0.01, observers 1 and 2). In conclusion, hybrid-protocol WB-MRA shows a better diagnostic performance than standard protocol WB-MRA at 3 T in patients with PAD.

Whole-body MRI in children: current status and future applications

Whole-body MRI (WBMRI) is a novel technique that makes imaging of the whole patient in a manner similar to scintigraphy or positron emission tomography (PET) possible. Unlike the latter two methods, it is without exposure to radiation and thus gaining increasing importance and application in pediatrics. With the introduction of a moving tabletop, sequential movement of the patient through the magnet has become possible with automatic direct realignment of the images after acquisition. The common scan plane is coronal with additional planes being added depending on the indication. WBMRI is targeted for maximum coverage of the body within the shortest possible time using the minimum number of sequences. The evaluation of the bone marrow has been the primary indication thus inversion recovery sequences like STIR or TIRM are mostly used with the T1-weighted sequence being added variably. For correct evaluation of the bone marrow in the pediatric age group understanding normal pattern of marrow transformation is essential. The primary role of WBMRI has been in oncology for the detection of tumor spread and also for the follow-up and evaluation of complications. The initial comparative studies of WBMRI with scintigraphy and PET in children have shown the high diagnostic potential of WBMRI. Emerging potential applications of WBMRI include the evaluation for osteonecrosis, chronic multifocal recurrent osteomyelitis, myopathies, and generalized vascular malformations. Future use of WBMRI may incorporate non-accidental trauma, virtual autopsy, body fat mapping and diffusion-weighted imaging.

Clinically Unrecognized Myocardial Infarction Detected at MR Imaging May Not Be Associated with Atherosclerosis

PURPOSE

To prospectively investigate whether there is support for the hypothesis that clinically unrecognized myocardial infarctions (UMIs) detected at magnetic resonance (MR) imaging have an atherosclerotic pathogenesis similar to that of recognized myocardial infarctions (RMIs).

MATERIALS AND METHODS

After ethics committee approval and informed consent were obtained, gadolinium-enhanced whole-body MR angiography and late-enhancement MR imaging were performed in 248 randomly chosen 70-year-old subjects (123 women, 125 men). Imaging included the aorta and the carotid, renal, and lower limb arteries to the ankle, but not the coronary arteries. Subjects with myocardial infarction (MI) scars at late-enhancement MR imaging were classified as having RMI (n=11) (those with a diagnosis of MI at the hospital) or UMI (n=49) (those without a diagnosis of MI at the hospital). The presence of 50% or higher luminal narrowing in any vessel at whole-body MR angiography was considered to represent significant atherosclerosis. Intima-media thickness of the common carotid artery was measured with ultrasonography. C-reactive protein level was measured, and coronary heart disease risk was estimated. Observers were blinded to any previous results. The chi2 test, analysis of variance, and Bonferroni correction were used for statistical analyses.

RESULTS

None of the measured parameters differed significantly between the group without MI scars and the UMI group, but parameters were significantly increased in the RMI group (P<.05) compared with those in the group without MI scars. Forty-two of 49 UMIs and nine of 11 RMIs were located within inferolateral segments of the left ventricle.

CONCLUSION

MR imaging-detected UMIs might have a different pathogenesis from that of RMIs or may have the same pathogenesis but may manifest at an earlier stage.

Whole-body screening of atherosclerosis with magnetic resonance angiography

With whole-body magnetic resonance angiography (WBMRA), it is possible to examine the whole arterial tree except intracranial and coronary vessels in a single examination without the risks involved in ionizing radiation or arterial cannulation. Whole-body magnetic resonance angiography is well suited for repeated clinical examinations in patients with systemic diseases such as vasculitis or atherosclerosis and can also be used for scientific purposes. On the basis of the WBMRA overview, a possible further development of the WBMRA concept can be to perform further acquisitions at sites with atherosclerotic plaques with higher-resolution scans to determine the degree of stenosis more accurately or to achieve plaque characterization. A total validation of WBMRA compared with digital subtraction angiography (DSA) is not possible owing to the hazards of ionizing radiation. Studies have shown a high sensitivity and specificity for the pelvic and lower limb arteries in comparison with DSA. No systematic validation against DSA has been performed for the renal, aortic, and carotid arteries. Various methods have been used, however, for confirmation of vascular abnormalities found on WBMRA such as ultrasonography, dedicated MRA, or DSA, with reasonably high agreement. The WBMRA method has not been studied with regard to prediction of future cardiovascular (CV) events, as have intima media thickness, coronary artery calcium scoring, and the ankle-brachial index. The full usefulness of WBMRA in an epidemiological setting and as a complementary screening tool for assessing CV risk still needs to be validated against future CV events.

Identification of the main arterial branches by whole-body contrast-enhanced MRA in elderly subjects using limited user interaction and fast marching

PURPOSE

To extract a graph model corresponding to a predefined set of arterial branches from whole-body contrast-enhanced magnetic resonance angiography (CE-MRA) data sets in elderly asymptomatic subjects, a high-incidence group.

MATERIALS AND METHODS

Maximum intensity projections (MIPs) were used as an interface to place landmarks in the three-dimensional (3D) data sets. These landmarks were linked together using fast marching to form a graph model of the arterial tree. Only vessels of interest were identified.

RESULTS

We tested our method on 10 subjects. We were able to build a graph model of the main arterial branches that performed well in the presence of vascular pathologies, such as stenosis and aneurysm. The results were rated by an experienced radiologist, with an overall success rate of 80%.

CONCLUSION

We were able to extract chosen arterial branches in 3D whole-body CE-MRA images with a moderate amount of interaction using a single MIP projection.

The Prevalence and Quantification of Atherosclerosis in an Elderly Population Assessed by Whole-Body Magnetic Resonance Angiography

OBJECTIVE

The principal aim of the present study was to explore the feasibility of using whole-body magnetic resonance angiography to assess atherosclerosis in different vascular territories in a cohort of elderly.

METHODS AND RESULTS

Three hundred six 70-year-old subjects (145 women, 161 men) recruited from a population-based cohort study (Prospective Investigation of the Vasculature in Uppsala Seniors, ie, the PIVUS study) underwent 1.5-T whole-body magnetic resonance angiography with gadodiamide. The arteries were divided into 26 segments. In total, 7956 vessel segments were evaluated with 7900 segments (99.3%) possible to evaluate. Of these, 7186 segments (91%) were normal. Luminal narrowing of > or = 50% was observed in 9 (1.5%) of the renal arteries, 12 (1.8%) of the carotid arteries, in 31 segments (1.1%) of the pelvic/upper leg territories, and in 136 segments (6.2%) of territories in the lower leg. Approximately one-third of the sample had no vascular abnormalities, one-third had stenoses of < 50%, and the remainder had stenoses > or = 50% or occlusions. Six subjects (2%) had aortic aneurysms. In subjects without evident vascular disease, 26% had significant vascular abnormalities.

CONCLUSIONS

Whole-body magnetic resonance angiography performed with a clinical scanner can be used for quantifying atherosclerosis in different vascular territories in a single examination in an elderly population.

3D contrast-enhanced MR angiography

Safe, fast, accurate contrast arteriography can be obtained utilizing gadolinium (Gd) and 3D MR data acquisition for diagnosing vascular diseases. Optimizing contrast enhanced MRA (CE MRA), however, requires understanding the complex interplay between Gd injection timing, the Fourier mapping of 3D MR data acquisition and a multitude of parameters determining resolution, anatomic coverage, and sensitivity to motion artifacts. It is critical to time the bolus peak to coincide with central k-space data acquisition, which dominates image contrast. Oversampling the center of k-space allows reconstruction of multiple 3D acquisitions in rapid succession to time-resolve the passage of the contrast bolus. Parallel imaging increases resolution, shortens scan time and compresses the center of k-space into a shorter period of time, thereby minimizing motion and timing artifacts. Absence of ionizing radiation allows MRA to be repeated and combined with additional sequences to more fully characterize anatomy, flow, and physiology. Utilizing stepping table technology and thigh compression, whole body MRA is possible with a single contrast injection. As MR technology continues to advance, CE MRA becomes better and simpler to perform, increasing its efficacy in the diagnosis and management of vascular diseases.