Delayed Contrast-Enhanced MRI of the Aortic Wall in Takayasu's Arteritis: Initial Experience

Late/delayed gadolinium enhancement in MRI after intravenous administration of extracellular gadolinium-based contrast agents: is it worth waiting?

The acquisition of images minutes or even hours after intravenous extracellular gadolinium-based contrast agents (GBCA) administration ("Late/Delayed Gadolinium Enhancement" imaging; in this review, further termed LGE) has gained significant prominence in recent years in magnetic resonance imaging. The major limitation of LGE is the long examination time; thus, it becomes necessary to understand when it is worth waiting time after the intravenous injection of GBCA and which additional information comes from LGE. LGE can potentially be applied to various anatomical sites, such as heart, arterial vessels, lung, brain, abdomen, breast, and the musculoskeletal system, with different pathophysiological mechanisms. One of the most popular clinical applications of LGE regards the assessment of myocardial tissue thanks to its ability to highlight areas of acute myocardial damage and fibrotic tissues. Other frequently applied clinical contexts involve the study of the urinary tract with magnetic resonance urography and identifying pathological abdominal processes characterized by high fibrous stroma, such as biliary tract tumors, autoimmune pancreatitis, or intestinal fibrosis in Crohn's disease. One of the current areas of heightened research interest revolves around the possibility of non-invasively studying the dynamics of neurofluids in the brain (the glymphatic system), the disruption of which could underlie many neurological disorders.

Arterial wall fibrosis in Takayasu arteritis and its potential for therapeutic modulation

Arterial wall damage in Takayasu arteritis (TAK) can progress despite immunosuppressive therapy. Vascular fibrosis is more prominent in TAK than in giant cell arteritis (GCA). The inflamed arterial wall in TAK is infiltrated by M1 macrophages [which secrete interleukin-6 (IL-6)], which transition to M2 macrophages once the inflammation settles. M2 macrophages secrete transforming growth factor beta (TGF-β) and glycoprotein non-metastatic melanoma protein B (GPNMB), both of which can activate fibroblasts in the arterial wall adventitia. Mast cells in the arterial wall of TAK also activate resting adventitial fibroblasts. Th17 lymphocytes play a role in both TAK and GCA. Sub-populations of Th17 lymphocytes, Th17.1 lymphocytes [which secrete interferon gamma (IFN-γ) in addition to interleukin-17 (IL-17)] and programmed cell death 1 (PD1)-expressing Th17 (which secrete TGF-β), have been described in TAK but not in GCA. IL-6 and IL-17 also drive fibroblast activation in the arterial wall. The Th17 and Th1 lymphocytes in TAK demonstrate an activation of mammalian target organ of rapamycin 1 (mTORC1) driven by Notch-1 upregulation. A recent study reported that the enhanced liver fibrosis score (derived from serum hyaluronic acid, tissue inhibitor of metalloproteinase 1, and pro-collagen III amino-terminal pro-peptide) had a moderate-to-strong correlation with clinically assessed and angiographically assessed vascular damage. In vitro experiments suggest the potential to target arterial wall fibrosis in TAK with leflunomide, tofacitinib, baricitinib, or mTORC1 inhibitors. Since arterial wall inflammation is followed by fibrosis, a strategy of combining immunosuppressive agents with drugs that have an antifibrotic effect merits exploration in future clinical trials of TAK.

The Treatment Dilemma of Arteriopathy in Takayasu Arteritis- A State-of-the-Art Approach

Takayasu Arteritis (TA) is a chronic idiopathic granulomatous pan-arteritis affecting the pulmonary artery, the aorta, and its principal derived branches. The majority of TA patients are female (82.9-97.0 percent). Due to the inflammatory character of the illness, arterial stenosis therapy must be treated differently than the atherosclerosis process. In this review paper, we outline a strategy using real-world challenging cases.

Overview of imaging in adult- and childhood-onset Takayasu arteritis

Takayasu Arteritis is an idiopathic large vessel vasculitis, that affects young adults and children and can lead to ischemia and end-organ damage. Vascular imaging is crucial for diagnosis, assessment of disease extent and management of the disease. In this article, we critically review evidence for the clinical use of the different imaging modalities conventional angiography, magnetic resonance imaging, computed tomography, Doppler ultrasound and ¹⁸fluorodeoxyglucose positron emission tomography. We thereby focus on their clinical applicability, challenges and specific use in children.

Detection of mural inflammation with low b-value diffusion-weighted imaging in patients with active Takayasu Arteritis

OBJECTIVES

To evaluate the performance of low b-value diffusion-weighted imaging (DWI) for detection of inflamed vessels in active Takayasu arteritis (TA).

METHODS

Forty patients with active TA involving the thoracic aorta and its super-aortic branches underwent low b-value (50 s/mm²) DWI, T2-weighted imaging (T2WI), and delayed enhancement T1-weighted imaging (DEI). Corresponding images on these 3 sequences at the same diseased level were evaluated qualitatively and quantitatively using Friedman and Kruskal-Wallis test, and the agreement between them in detection of inflamed vessels was assessed using Cochran's Q test.

RESULTS

The overall image quality of DEI, DWI, and T2WI was scored 7.97 ± 1.15, 7.32 ± 1.73, and 6.51 ± 1.69 respectively. The score of DEI and DWI was higher than that of T2WI (p < 0.001). The quality of blood suppression was rated higher in DWI than T2WI and DEI (p < 0.001). Both the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the diseased vessel walls measured on DEI and DWI were significantly higher than those on T2WI (p < 0.001). However, there was no significant difference in SNR and CNR between DEI and DWI (p = 0.283 and 0.063). In detection of mural inflammation, significant advantage was observed when comparing the findings from DEI/DWI to those from T2WI (p < 0.001). But no significant difference was found between the findings of DWI and DEI (p > 0.99).

CONCLUSIONS

Low b-value DWI may be used as a promising alternative to DEI for detecting inflamed vessels in active TA.

KEY POINTS

• Currently, the most widely used imaging modality in detection of mural inflammation is contrast-enhanced MRI. • Low b-value DWI is shown comparable to contrast-enhanced MRI and superior to T2WI in identifying mural inflammation in patients with active Takayasu arteritis. • Low b-value DWI is a fast and unenhanced MRI technique which may potentially replace contrast-enhanced MRI in identifying disease activity of Takayasu arteritis.

Potential Applications of PET Scans, CT Scans, and MR Imaging in Inflammatory Diseases: Part II: Cardiopulmonary and Vascular Inflammation

Detecting inflammation is among the most important aims of medical imaging. Inflammatory process involves immune system activity and local tissue response. The role of PET with fludeoxyglucose F 18 has been expanded. Systemic vasculitides and cardiopulmonary inflammatory disorders constitute a wide range of diseases with multisystemic manifestations. PET with fludeoxyglucose F 18 is useful in their diagnosis, assessment, and follow-up. This article provides an overview of the current status and potentials of hybrid molecular imaging in evaluating cardiopulmonary and vascular inflammatory diseases focusing on the potential for PET with fludeoxyglucose F 18/MR imaging and PET/CT scans.

PET/MRI in large-vessel vasculitis: clinical value for diagnosis and assessment of disease activity

Diagnosis of large vessel vasculitis (LVV) and evaluation of its inflammatory activity can be challenging. Our aim was to investigate the value of hybrid positron-emission tomography/magnetic resonance imaging (PET/MRI) in LVV. All consecutive patients with LVV from the Department of Internal Medicine who underwent PET/MRI were included. Three PET/MRI patterns were defined: (i) "inflammatory," with positive PET (>liver uptake) and abnormal MRI (stenosis and/or wall thickening); (ii) "fibrous", negative PET (≤liver uptake) and abnormal MRI; and (iii) "normal". Thirteen patients (10 female; median age: 67-years [range: 23-87]) underwent 18 PET/MRI scans. PET/MRI was performed at diagnosis (n = 4), at relapse (n = 7), or during remission (n = 7). Among the 18 scans, eight (44%) showed an inflammatory pattern and three (17%) a fibrous pattern; the other seven were normal. The distribution of the three patterns did not differ between patients with Takayasu arteritis (TA, n = 10 scans) and those with giant cell arteritis (GCA, n = 8 scans). PET/MRI findings were normal in 2/10 (20%) TA scans vs. 5/8 (62%) GCA scans (p = 0.3). Median SUVmax was 4.7 [2.1-8.6] vs. 2 [1.8-2.6] in patients with active disease vs. remission, respectively (p = 0.003). PET/MRI is a new hybrid imaging modality allowing comprehensive and multimodal analysis of vascular wall inflammation and the vascular lumen. This technique offers promising perspectives for the diagnosis and monitoring of LVV.

Takayasu arteritis: clinical importance of extra-vessel uptake on FDG PET/CT

Background

[F-18]fluorodeoxyglucose positron emission tomography/computed tomography is routinely used for assessing Takayasu arteritis patients. However, extra-vessel [F^-18]fluorodeoxyglucose uptake has not been evaluated in detail in these patients. We aimed to describe the extent and distribution of extra-vascular [F-18]fluorodeoxyglucose uptake on positron emission tomography/computed tomography in Takayasu arteritis patients. Seventy-three [F-18]fluorodeoxyglucose positron emission tomography/computed tomography scans from 64 consecutive Takayasu arteritis patients (59 women, mean age, 35.4 years; range, 13 to 71 years) and 40 scans from age-matched controls (36 women, mean age, 37.8 years; range, 13 to 70 years) were examined. We graded [F-18]fluorodeoxyglucose uptake in large vessels using a 4-point scale and evaluated extra-vessel findings. Factors correlated with disease activity were examined. We evaluated the relationship between disease activity according to the National Institutes of Health score with extra-vessel findings, as well as other inflammatory markers (e.g., white blood cell count and C-reactive protein level).

Results

Extra-vessel involvement was present in 50 of 73 (68.4%) scans, specifically at the following sites: lymph nodes, 1.4%; thyroid glands, 17.8%; thymus, 11.0%; spleen, 1.4%; vertebrae, 45.2%; and pelvic bones, 9.6%. Takayasu arteritis patients had higher [F-18]fluorodeoxyglucose uptake in the spine (P = 0.03) and thyroid glands (P = 0.003) than did controls; uptake in other regions was comparable between groups. Compared with inactive patients, those with active Takayasu arteritis had a higher number of [F-18]fluorodeoxyglucose uptake sites in the vasculature (P = 0.001). Finally, patients with a National Institutes of Health score of ≥ 1 had significantly higher extra-vascular involvement (P = 0.008).

Conclusions

Extra-vessel [F-18]fluorodeoxyglucose uptake may be present in the context of Takayasu arteritis-related inflammatory processes. Information on extra-vascular [F-18]fluorodeoxyglucose uptake may be useful for detecting and evaluating inflammatory processes when interpreting positron emission tomography/computed tomography scans obtained from Takayasu arteritis patients.

Pulmonary vasculitis: diagnosis and endovascular therapy

Pulmonary vasculitides are caused by a heterogeneous group of diseases with different clinical features and etiologies. Radiologic manifestations depend on the predominant type of vessel involved, which are grouped into large, medium, or small-sized vessels. Diagnosing pulmonary vasculitides is a challenging task, and radiologists play an important role in their management by providing supportive evidence for diagnosis and opportunities for minimally invasive therapy. This paper aims to present a practical approach for understanding the vasculitides that can affect the pulmonary vessels and lungs. We will describe and illustrate the main radiologic findings, discussing opportunities for minimally invasive treatment.

Spectrum of Aortic Disease in the Giant Cell Arteritis Population

We report the spectrum of aortic involvement in patients with giant cell arteritis (GCA) following review of medical records of 4,006 patients including those with imaging studies. A total of 1,450 patients (36%) had a confirmed diagnosis of GCA. Of these, 974 had aortic imaging. Of the 974 patients with imaging, 435 (45%) had an identified aortopathy. The most common aortopathy was aneurysm/dilation (69%). Overall, an annual aneurysmal growth rate of 1.5 mm/y was calculated. In patients with aneurysm/dilation, aortic dissection occurred in 18 patients (6%), and these patients had a significantly higher aneurysmal growth rate compared with those without dissection (4.5 vs 1.4 mm/y, p = 0.005). The median size of the aorta at the time of dissection was 51 mm, with 7 (39%) occurring with a maximal aortic aneurysm/dilation <50 mm. In conclusion, our findings indicate higher aneurysmal growth rate in GCA compared with that reported for degenerative aortic disease. Moreover, patients who develop dissection had a significantly higher growth rate than those without dissection with over a third of these patients suffering dissection at a caliber <50 mm.

Evaluation of takayasu arteritis with delayed contrast-enhanced MR imaging by a free-breathing 3D IR turbo FLASH

The primary aim of our case-control study was to observe delayed contrast-enhanced magnetic resonance imaging (DCE-MRI) in patients with Takayasu arteritis (TA) in comparison with magnetic resonance angiography (MRA). Twenty-seven patients including 15 with active TA and 12 with stable TA who underwent both aortic MRA and DCE-MRI were included. A total of 27 sex- and age-matched healthy volunteers were enrolled as the control group. MRA were obtained with T1WI-volume-interpolated breath-hold examination sequence or fast low-angle shot (FLASH) sequence. DCE-MRI was acquired with a free-breathing three-dimensional inversion recovery Turbo fast low-angle shot (3D IR Turbo FLASH). Neither stenosis nor delayed enhancement of arterial wall was shown in the control group. In patients with stable TA, arterial stenosis was observed on MRA. On DCE-MR, delayed enhancement of arterial walls could be observed in the active TA group but not in the stable TA group or the control group. Stenotic arteries on MRA were comparable in the active TA and stable TA (χ = 2.70, P = .259); however, delayed enhancement of arterial walls in the active-TA group were more than those in the stable group (χ = 27.00, P < .001). Our results suggest that DCE-MRI with the free-breathing 3D IR Turbo FLASH sequence could assess TA and delayed enhancement on DCE-MRI is one characteristics of the active TA.

Contrast-enhanced magnetic resonance imaging for the detection of ruptured coronary plaques in patients with acute myocardial infarction

Purpose

X-ray coronary angiography (XCA) is the current gold standard for the assessment of lumen encroaching coronary stenosis but XCA does not allow for early detection of rupture-prone vulnerable plaques, which are thought to be the precursor lesions of most acute myocardial infarctions (AMI) and sudden death. The aim of this study was to investigate the potential of delayed contrast-enhanced magnetic resonance coronary vessel wall imaging (CE-MRCVI) for the detection of culprit lesions in the coronary arteries.

Methods

16 patients (13 male, age 61.9±8.6 years) presenting with sub-acute MI underwent CE-MRCVI within 24-72h prior to invasive XCA. CE-MRCVI was performed using a T1-weighted 3D gradient echo inversion recovery sequence (3D IR TFE) 40±4 minutes following the administration of 0.2 mmol/kg gadolinium-diethylenetriamine-pentaacetic acid (DTPA) on a 3T MRI scanner equipped with a 32-channel cardiac coil.

Results

14 patients were found to have culprit lesions (7x LAD, 1xLCX, 6xRCA) as identified by XCA. Quantitative CE-MRCVI correctly identified the culprit lesion location with a sensitivity of 79% and excluded culprit lesion formation with a specificity of 99%. The contrast to noise ratio (CNR) of culprit lesions (9.7±4.1) significantly exceeded CNR values of segments without culprit lesions (2.9±1.9, p<0.001).

Conclusion

CE-MRCVI allows the selective visualization of culprit lesions in patients immediately after myocardial infarction (MI). The pronounced contrast uptake in ruptured plaques may represent a surrogate biomarker of plaque activity and/or vulnerability.

Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins

Objectives

The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease.

Methods

Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified.

Results

An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI.

Conclusions

This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population.

Key points

• BMI-discordant twins allow the investigation of the influence of lifestyle factors independent from genetic confounders.

• Only thirteen obesity-discordant twins were identified underlining the strong genetic component of BMI.

• In female twins, a BMI increase is associated with increased coronary late gadolinium enhancement.

• Increased late gadolinium enhancement in the coronary vessel wall potentially reflects increased atherosclerosis.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-016-4616-8) contains supplementary material, which is available to authorized users.

Vessel Wall Inflammation of Takayasu Arteritis Detected by Contrast-Enhanced Magnetic Resonance Imaging: Association with Disease Distribution and Activity

AIMS

The assessment of the distribution and activity of vessel wall inflammation is clinically important in patients with Takayasu arteritis. Magnetic resonance imaging (MRI) is a useful tool, but the clinical utility of late gadolinium enhancement (LGE) in Takayasu arteritis has yet to be determined. The aim of the present study was to evaluate the utility of LGE in assessing vessel wall inflammation and disease activity in Takayasu arteritis.

METHODS AND RESULTS

We enrolled 49 patients with Takayasu arteritis who had undergone 1.5 T MRI. Patients were divided into Active (n = 19) and Inactive disease (n = 30) groups. The distribution of vessel wall inflammation using angiography and LGE was assessed by qualitative analysis. In 79% and 63% of patients in Active and Inactive groups, respectively, greater distribution of vessel wall inflammation was observed with LGE than with conventional angiography. MRI values of pre- and post-contrast signal-to-noise ratios (SNR), SNR increment (post-SNR minus pre-SNR), pre- and post-contrast contrast-to-noise ratios (CNR), and CNR increment (post-CNR minus pre-CNR) were evaluated at arterial wall sites with the highest signal intensity using quantitative analysis of post-contrast LGE images. No statistically significant differences in MRI parameters were observed between Active and Inactive groups. Contrast-enhanced MRI was unable to accurately detect active disease.

CONCLUSION

Contrast-enhanced MRI has utility in detecting the distribution of vessel wall inflammation but has less utility in assessing disease activity in Takayasu arteritis.

Adjunctive testing in the evaluation of adults after Kawasaki disease

Acute Kawasaki disease (KD) is diagnosed and treated by pediatricians, but decades later, these individuals are presenting to adult cardiologists with a variety of cardiovascular sequelae, including myocardial ischemia and infarction, congestive heart failure secondary to myocardial fibrosis, and claudication because of vascular insufficiency from thrombosed peripheral arteries. There are no clinical trials to guide management, interventions, and medical therapy in this patient population. This review summarizes the emerging information regarding evaluation of the cardiovascular status of adults decades after childhood KD.

Management of the renovascular disease in children with Takayasu arteritis

Takaysu arteritis (TA), together with fibromuscular dysplasia, is the most common cause for renovascular hypertension. The diagnosis of vasculitis is important to make as these children benefit from immunosuppressive treatment. In many cases, however, it is more difficult than commonly realised to differentiate between these two diagnoses. Imaging which allows the inflamed arterial wall to be outlined, such as magnetic resonance or positron emission tomography scans, can be very helpful in this context. Revascularisation, either with angioplasty or surgery, seems to be effective and safe, also in children with TA. Patients with inactive disease have a more successful outcome and experience fewer complications from the intervention than those with active on-going inflammation.

CT and MRI in the Evaluation of Thoracic Aortic Diseases

Computed tomography (CT) and magnetic resonance imaging (MRI) are the most commonly used imaging examinations to evaluate thoracic aortic diseases because of their high spatial and temporal resolutions, large fields of view, and multiplanar imaging reconstruction capabilities. CT and MRI play an important role not only in the diagnosis of thoracic aortic disease but also in the preoperative assessment and followup after treatment. In this review, the CT and MRI appearances of various acquired thoracic aortic conditions are described and illustrated.

Magnetic resonance imaging of cardiovascular fibrosis and inflammation: from clinical practice to animal studies and back

Late gadolinium enhancement is the technique of choice for detecting myocardial fibrosis. Although this technique is used in a wide range of cardiovascular pathologies, ischemic cardiomyopathy and the workup for myocarditis and other cardiomyopathies make up a significant proportion of the total indications. Multiple studies during the last decade have demonstrated its utility to adequately characterize myocardial tissue and offer diagnostic and prognostic information. Recent T1 mapping techniques aim to overcome the limitations of late gadolinium enhancement to assess diffuse fibrosis. ¹⁹F magnetic resonance has recently emerged as a promising technique for the assessment of inflammation. In the following review we will discuss the basic aspects of fibrosis assessment with MR and its utility for diagnostic and prognostic evaluation. We will also address the topic of cardiovascular inflammation imaging with ¹⁹F as a potential new development that may broaden the indications for MR in the future.

Adverse results of a decellularized tissue-engineered pulmonary valve in humans assessed with magnetic resonance imaging

OBJECTIVES

Matrix P® and Matrix P plus® tissue-engineered pulmonary valves (TEPV) were offered as an improvement for pulmonary valve replacement (PVR) because of recellularization by host cells. The high frequency of graft failure gave reason to evaluate the underlying morphological substrate using magnetic resonance imaging (MRI) and histology.

METHODS

Between June 2006 and August 2008, 17 Matrix P® and 10 Matrix P plus® TEPVs were implanted in 26 patients with a median age of 12.4 (range: 0.8-38.7, interquartile range: 6.1-18.1) years. The grafts were studied by MRI, and underwent histological examination when explantation was required.

RESULTS

Surgical (n = 13) or transcatheter (n = 1) TEPV replacement because of graft failure was needed in 14 cases (52%) 19 (0.5-53) months after implantation. MRI detected significant TEPV stenosis with mild insufficiency (V(max) = 3.7 ± (standard deviation) 0.5 m/s, regurgitant fraction (RGF) = 10 ± 3%) and stenosis with moderate-to-severe insufficiency (V(max) = 3.5 ± 0.8 m/s, RGF = 38 ± 10%) in 6 patients, respectively, and severe insufficiency (RGF = 40%) in 1 patient. In patients with graft failure, MRI showed hyperenhancement and TEPV wall thickening. Histology revealed severe inflammation, increased fibrous tissue and foreign-body reaction against valve leaflets and fascial tissue, while TEPV endothelialization was not detected in any case.

CONCLUSIONS

The high frequency of Matrix P® and Matrix P plus® graft failure can be related to inflammation and fibrosis revealed by MRI and histology. Our results do not support the use of these valves for PVR and suggest careful follow-up examinations, including MRI for early detection of graft inflammation and fibrosis.

Takayasu arteritis: diagnosis, treatment and prognosis

Takayasu arteritis (TA) is a chronic nonspecific granulomatous vasculitis affecting aorta and its main branches, coronary and pulmonary arteries. TA often occurs in young women and has a characteristic heterogeneity depending on ethnicity and geographical location. Although the pathogenesis of TA remains unclear, the interaction of many factors, such as autoimmunity, inflammation, genetic and environmental factors and so on, is involved in the occurrence and development of TA. Angiography, which is recognized as the gold standard in evaluating vascular lesions in TA, combined with computer tomography angiography (CTA), magnetic resonance angiography (MRA), ultrasonography, (18)Fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) could not only provide important information for early diagnosis but also detect disease activity, and thus further guide the treatment in TA. In addition, beside the commonly used corticosteroids, immunosuppressive agents, percutaneous transluminal angioplasty (PTA) and surgical revascularization, anti-tumor necrosis factor (TNF) agent has been more widely used in refractory cases of TA. The objective of this review is to systemically describe the pathogenesis, clinical characteristics, diagnosis, treatment and prognosis of TA.

Renovascular hypertension--is it fibromuscular dysplasia or Takayasu arteritis

Renovascular hypertension (RVH) can be caused by many different diseases, with the most common being fibromuscular dysplasia (FMD) and Takayasu arteritis (TA). A strikingly different diagnostic pattern is seen in children with RVH from different parts of the world. In Europe and North America, these children are mainly diagnosed as having FMD while in Asia and South Africa they will most often get a diagnosis of TA. When comparing the clinical diagnosis for FMD and TA, it becomes obvious that there is a great deal of overlap between the definitions of these two conditions. Different ways to come to the most accurate diagnosis using imaging of the blood vessel wall and positron emission tomography (PET) will be discussed. How an accurate diagnosis should influence the treatment of the children with these conditions will also be addressed.

Delayed contrast-enhanced MRI of the coronary artery wall in takayasu arteritis

BACKGROUND

Takayasu arteritis (TA) is a rare form of chronic inflammatory granulomatous arteritis of the aorta and its major branches. Late gadolinium enhancement (LGE) with magnetic resonance imaging (MRI) has demonstrated its value for the detection of vessel wall alterations in TA. The aim of this study was to assess LGE of the coronary artery wall in patients with TA compared to patients with stable CAD.

METHODS

We enrolled 9 patients (8 female, average age 46±13 years) with proven TA. In the CAD group 9 patients participated (8 male, average age 65±10 years). Studies were performed on a commercial 3T whole-body MR imaging system (Achieva; Philips, Best, The Netherlands) using a 3D inversion prepared navigator gated spoiled gradient-echo sequence, which was repeated 34-45 minutes after low-dose gadolinium administration.

RESULTS

No coronary vessel wall enhancement was observed prior to contrast in either group. Post contrast, coronary LGE on IR scans was detected in 28 of 50 segments (56%) seen on T2-Prep scans in TA and in 25 of 57 segments (44%) in CAD patients. LGE quantitative assessment of coronary artery vessel wall CNR post contrast revealed no significant differences between the two groups (CNR in TA: 6.0±2.4 and 7.3±2.5 in CAD; p = 0.474).

CONCLUSION

Our findings suggest that LGE of the coronary artery wall seems to be common in patients with TA and similarly pronounced as in CAD patients. The observed coronary LGE seems to be rather unspecific, and differentiation between coronary vessel wall fibrosis and inflammation still remains unclear.

Detection and grading of coronary allograft vasculopathy in children with contrast-enhanced magnetic resonance imaging of the coronary vessel wall

BACKGROUND

Coronary allograft vasculopathy is the leading cause of late death after heart transplantation in children. It is poorly detected by conventional angiography. Intravascular ultrasound is invasive and costly. This study shows that magnetic resonance imaging (MRI) late gadolinium enhancement (LGE) of the coronary vessel wall can detect and grade coronary allograft vasculopathy.

METHODS AND RESULTS

Twenty-four children (10 male; age range, 9-17 years) underwent coronary angiography, intravascular ultrasound, and MRI. Maximal intimal thickness and mean intimal index were recorded. MRI included coronary magnetic resonance angiogram and LGE vessel wall imaging with 1.5 T (n=12) and 3.0 T (n=12). Ten healthy control subjects also underwent LGE MRI. Mean time posttransplantation was 5.5 years (range, 0.25-14 years). Seven patients had Stanford grade IV coronary allograft vasculopathy on intravascular ultrasound, 3 of whom had angiographic disease. Maximal intimal thickness and mean intimal index were 0.73±0.50 mm and 20.9±10.6%, respectively. On MRI, mean diameter of enhancement of vessel wall was 6.57±4.91 mm, and mean enhancement index (indexed to vessel lumen size) was 1.10±1.72. The control group showed little or no LGE. Correlation of LGE with maximal intimal thickness using the Pearson coefficient was 0.80 (P<0.001) and with mean intimal index was 0.92 (P<0.001). An MRI diameter >7.5 mm gave 86% sensitivity and 93% specificity.

CONCLUSIONS

LGE scores correlate well with traditional intravascular ultrasound measures. These promising early results encourage larger-scale clinical studies to investigate whether LGE MRI will allow closer follow-up and better prevention of coronary allograft vasculopathy in children.

CMR in inflammatory vasculitis

Vasculitis, the inflammation of blood vessels, can produce devastating complications such as blindness, renal failure, aortic rupture and heart failure through a variety of end-organ effects. Noninvasive imaging with cardiovascular magnetic resonance (CMR) has contributed to improved and earlier diagnosis. CMR may also be used in serial evaluation of such patients as a marker of treatment response and as an indicator of subsequent complications. Unique strengths of CMR favoring its use in such conditions are its abilities to noninvasively visualize both lumen and vessel wall with high resolution. This case-based review focuses on the large- and medium-vessel vasculitides where MR angiography has the greatest utility. Because of increasing recognition of cardiac involvement in small-vessel vasculitides, this review also presents evidence supporting greater consideration of CMR to detect and quantify myocardial microvascular disease. CMR's complementary role amidst traditional clinical, serological and other diagnostic techniques in personalized care for patients with vasculitis is emphasized. Specifically, the CMR laboratory can address questions related to extent and severity of vascular involvement. As ongoing basic and translational studies better elucidate poorly-defined underlying molecular mechanisms, this review concludes with a discussion of potential directions for the development of more targeted imaging approaches.

Evaluation of the aortic root with MRI and MDCT angiography: spectrum of disease findings

OBJECTIVE

This article reviews the spectrum of disease processes that may involve the aortic root with particular emphasis on the role of cardiovascular MRI and MDCT angiography in their assessment. Key MRI and MDCT imaging findings are discussed and illustrated.

CONCLUSION

Radiologists should be aware of the spectrum of disease processes that may involve the aortic root and their appearances at MRI and MDCT angiography.

Insights into imaging of aortitis

BACKGROUND

Aortitis is a subtype of the more general term "vasculitis", an inflammatory condition of infectious or noninfectious origin involving the vessel wall. The term "vasculitis" refers to a broad spectrum of diseases with different aetiologies, pathophysiologies, clinical presentations and prognoses. The clinical manifestations are nonspecific, as are the laboratory findings such as pain, fever, weight loss, vascular insufficiency and elevated levels of acute phase reactants, as well as other systemic manifestations, and sometimes may mimic other entities. Thus, if not suspected as part of the initial differential diagnosis, aortitis can be overlooked during the workup of patients with constitutional symptoms and systemic disorders.

METHODS

Imaging is rarely used for the primary diagnosis, but imaging findings, although nonspecific, can help in the assessment of these patients and is often required for making the final diagnosis. Imaging can be critical in the initiation of appropriate management and therapy.

RESULTS

Noninvasive cross-sectional imaging modalities such as contrast-enhanced CT, magnetic resonance (MR) imaging, nuclear medicine and in particular positron emission tomography (PET) are the leading modalities in modern diagnostic imaging of aortitis for both the initial diagnosis and follow-up.

CONCLUSION

This review focusses on the most common manifestations of aortitis with which radiologists should be familiar. TEACHING POINTS : • Aortitis is an inflammatory condition of infectious/noninfectious origin involving the vessel wall. • Imaging findings can help in the assessment of aortitis and are often crucial for the final diagnosis. • Contrast-enhanced CT, MRI and PET-CT are used for both the initial diagnosis and follow-up of aortitis.

The emerging role of cardiovascular MRI for suspected cardioembolic stroke

Stroke is a leading cause of morbidity and long-term disability worldwide and is often the result of embolic material from the heart or proximal aorta. These are referred to as cardioembolic sources of stroke. The investigation of patients with suspected cardioembolic stroke has traditionally been the mainstay of echocardiography. Cardiac magnetic resonance imaging (MRI) is a powerful imaging technique that has rapidly evolved over the last decade and is playing an ever increasing role in clinical cardiovascular imaging. This review of the literature aims to furnish the reader with an understanding of the role of cardiac MRI across the spectrum of causes of cardioembolic sources of stroke by providing the reader with an overview of the indications, technical considerations, a proposed imaging algorithm, and capabilities of this technology with selected illustrated examples of disease entities.

[Useful imaging techniques in the diagnosis and follow up of large vessel vasculitis: eco-doppler, angio-CT, angio-RM]

Although most vasculitis require histological proof for a definitive diagnosis, diagnostic imaging can be very helpful in this regard, allowing a proper evaluation of the vascular system and monitoring the response to treatment. Even though vasculitis is constituted by different pathological substrates, they show a common semiologic pattern from a radiological standpoint which is represented by inflammation, arterial wall thickening, and potential secondary development of vascular stenosis, occlusions or aneurysms. Differential diagnosis among diverse entities is based, beside clinical criteria, on the anatomical location and topography of the affected vascular territory. The general radiologic semiology is described in this paper from the perspective of the different imaging techniques, addressing their main advantages and drawbacks. Proper knowledge of this techniques will allow us to select the most appropiate one for each clinical condition.