Novel 3D-CT evaluation of carotid stent volume: greater chronological expansion of stents in patients with vulnerable plaques

Introduction

Although self-expanding carotid stents may dilate gradually, the degrees of residual stenosis have been quantified by the NASCET criteria, which is too simple to reflect the configuration of the stented artery. We measured the volumes of the stent lumens chronologically by 3D-CT in patients after carotid artery stenting (CAS), and analyzed the correlations between the volume change and medical factors.

Methods

Fourteen patients with carotid artery stenosis were treated using self-expanding, open-cell stents. All patients underwent preoperative plaque MRI (magnetization-prepared rapid acquisition gradient-echo, MPRAGE) and chronological 3D-CT examinations of their stents immediately after their placement and 1 day, 1 week, and 1 month after the procedure. The volume of the stent lumen was measured using a 3D workstation. The correlations between stent volume and various factors including the presence of underlying diseases, plaque characteristics, and the results of the CAS procedure were analyzed.

Results

Stent volume gradually increased in each case and had increased by 1.04–1.55 (mean, 1.25)-fold at 1 postoperative month. The presence of underlying medical diseases, plaque length, the degree of residual stenosis immediately after CAS, and plaque calcification did not have an impact on the change in stent volume. On the other hand, the stent volume increase was significantly larger in the patients with vulnerable plaques that demonstrated high MPRAGE signal intensity (P?<?0.05).

Conclusions

A 3D-CT examination is useful for precisely measuring stent volume. Self-expanding stents in carotid arteries containing vulnerable plaques expand significantly more than those without such plaques in a follow-up period.     

Magnetic resonance plaque imaging to predict the occurrence of the slow-flow phenomenon in carotid artery stenting procedures

Introduction

The purpose is to investigate the feasibility of magnetic resonance (MR) plaque imaging in predicting the arterial flow impairment (slow-flow phenomenon) during carotid artery stenting (CAS) using a filter-type protection device.

Methods

Thirty-one carotid artery stenotic lesions in 30 patients (28 men and two women; mean age, 71.8 years) were evaluated by MR plaque imaging with black blood T1- and T2-weighted and time-of-flight sequences before CAS. Main plaque components were classified as vulnerable (intraplaque hemorrhage and lipid-rich/necrotic core) or stable (fibrous tissue and dense calcification) from the signal pattern. The plaque classification was statistically compared with the occurrence of slow-flow phenomenon.

Results

The slow-flow phenomenon was observed in ten CAS procedures (five flow arrests and five flow reductions). Flow arrests consisted of four vulnerable and one stable plaque, and flow reductions consisted of four vulnerable and one stable plaque. The slow-flow phenomenon occurred significantly (P?<?0.01) more frequently in patients with vulnerable plaque.

Conclusions

Vulnerable carotid plaques have a significantly higher risk of slow-flow phenomenon than stable plaques. The occurrence of the slow-flow phenomenon can be predicted by MR plaque imaging before CAS.     

Quantitative assessment of changes in carotid plaques during cilostazol administration using three-dimensional ultrasonography and non-gated magnetic resonance plaque imaging

Introduction

Cilostazol, an antiplatelet agent, is reported to induce the regression of atherosclerotic changes. However, its effects on carotid plaques are unknown. Hence, we quantitatively investigated the changes that occur within carotid plaques during cilostazol administration using three-dimensional (3D) ultrasonography (US) and non-gated magnetic resonance (MR) plaque imaging.

Methods

We prospectively examined 16 consecutive patients with carotid stenosis. 3D-US and T1-weighted MR plaque imaging were performed at baseline and 6?months after initiating cilostazol therapy (200?mg/day). We measured the volume and grayscale median (GSM) of the plaques from 3D-US data. We also calculated the contrast ratio (CR) of the carotid plaque against the adjacent muscle and areas of the intraplaque components: fibrous tissue, lipid, and hemorrhage components.

Results

The plaque volume on US decreased significantly (median at baseline and 6?months, 0.23 and 0.21?cm³, respectively; p?=?0.03). In the group exhibiting a plaque volume reduction of more than 10%, GSM on US increased significantly (24.8 and 71.5, respectively; p?=?0.04) and CR on MRI decreased significantly (1.13 and 1.04, respectively; p?=?0.02). In this group, in addition, the percent area of the fibrous component on MRI increased significantly (68.6% and 79.4%, respectively; p?=?0.02), while those of the lipid and hemorrhagic components decreased (24.9% and 20.5%, respectively; p?=?0.12) (1.0% and 0.0%, respectively; p?=?0.04). There were no substantial changes in intraplaque characteristics in either US or MRI in the other group.

Conclusions

3D-US and MR plaque imaging can quantitatively detect changes in the size and composition of carotid plaques during cilostazol therapy.     

Uptake of F-18 FDG and ultrasound analysis of carotid plaque

Objectives

To elucidate the relation between the echolucent plaque on carotid ultrasound and acute inflammation on F-18 FDG carotid PET/CT.

Methods

Thirty nine patients (M:F ratio = 23:16, mean age = 63 ± 11 years) that underwent coronary angiography and carotid ultrasound were divided into three groups—echolucent plaque (n = 22), calcified (n = 10), and no plaque(n = 7). All the patients underwent F-18 FDG carotid PET/CT. The mean standardized uptake values (SUV), namely target to background ratio (TBR) on 180 minutes delayed F-18 FDG carotid PET/CT images were compared with levels of serum inflammatory markers and lipid profiles, and in terms of the presence of carotid plaque on carotid US.

Results

180 minutes TBR of carotid arterial wall at echolucent plaque, calcified plaque, and no plaque were 1.40 ± 0.05, 1.23 ± 0.03, 1.17 ± 0.03 in both carotid artery. TBR of carotid arterial walls for echolucent plaque were significantly larger than TBR for calcified, and no plaque respectively at the both side of carotid artery (P < .05). Serum HDL levels were found to be inversely correlated with F-18 FDG uptake at both carotid arteries (r = ?0.43, P = .005) on 180 minutes delayed phase images. Also serum hs-CRP levels were found to be correlated with F-18 FDG TBR values of right carotid arteries (r = 0.41, P = .04).

Conclusions

Our results show that F-18 FDG carotid PET/CT can depict metabolically active atherosclerotic plaques, and suggest that F-18 FDG carotid PET/CT can be used as a noninvasive imaging modality for functional evaluation of atherosclerosis.     

Spectral CT of carotid atherosclerotic plaque: comparison with histology

Objective

To distinguish components of vulnerable atherosclerotic plaque by imaging their energy response using spectral CT and comparing images with histology.

Methods

After spectroscopic calibration using phantoms of plaque surrogates, excised human carotid atherosclerotic plaques were imaged using MARS CT using a photon-processing detector with a silicon sensor layer and microfocus X-ray tube (50?kVp, 0.5?mA) at 38-μm voxel size. The plaques were imaged, sectioned and re-imaged using four threshold energies: 10, 16, 22 and 28?keV; then sequentially stained with modified Von Kossa, Perl’s Prussian blue and Oil-Red O, and photographed. Relative Hounsfield units across the energies were entered into a linear algebraic material decomposition model to identify the unknown plaque components.

Results

Lipid, calcium, iron and water-like components of plaque have distinguishable energy responses to X-ray, visible on spectral CT images. CT images of the plaque surface correlated very well with histological photographs. Calcium deposits (>1,000?μm) in plaque are larger than iron deposits (<100?μm), but could not be distinguished from each other within the same voxel using the energy range available.

Conclusions

Spectral CT displays energy information in image form at high spatial resolution, enhancing the intrinsic contrast of lipid, calcium and iron within atheroma.

Key Points

? Spectral computed tomography offers new insights into tissue characterisation. ? Components of vulnerable atherosclerotic plaque are spectrally distinct with intrinsic contrast. ? Spectral CT of excised atherosclerotic plaques can display iron, calcium and lipid. ? Calcium deposits are larger than iron deposits in atheroma. ? Spectral CT may help in the non-invasive detection of vulnerable plaques.     

Quantitative assessment of atherosclerotic plaques on <Superscript>18</Superscript>F-FDG PET/MRI: comparison with a PET/CT hybrid system

Purpose

PET with ¹⁸F-FDG has the potential to assess vascular macrophage metabolism. ¹⁸F-FDG is most often used in combination with contrast-enhanced CT to localize increased metabolism to specific arterial lesions. Novel ¹⁸F-FDG PET/MRI hybrid imaging shows high potential for the combined evaluation of atherosclerotic plaques, due to the superior morphological conspicuity of plaque lesions. The purpose of this study was to evaluate the reliability and accuracy of ¹⁸F-FDG PET/MRI uptake quantification compared to PET/CT as a reference standard in patients with carotid atherosclerotic plaques.

Methods

The study group comprised 34 consecutive oncological patients with carotid plaques who underwent both PET/CT and PET/MRI with ¹⁸F-FDG on the same day. The presence of atherosclerotic plaques was confirmed by 3 T MRI scans. Maximum standardized uptake values (SUV_max) for carotid plaque lesions and the average SUV of the blood pool within the adjacent internal jugular vein were determined and target-to-blood ratios (TBRs, plaque to blood pool) were calculated.

Results

Atherosclerotic lesions with maximum colocalized focal FDG uptake were assessed in each patient. SUV_max values of carotid plaque lesions were significantly lower on PET/MRI than on PET/CT (2.3?±?0.6 vs. 3.1?±?0.6; P?<?0.01), but were significantly correlated between PET/CT and PET/MRI (Spearman’s r?=?0.67, P?<?0.01). In contrast, TBR_max values of plaque lesions were similar on PET/MRI and on PET/CT (2.2?±?0.3 vs. 2.2?±?0.3; P?=?0.4), and again were significantly correlated between PET/MRI and PET/CT (Spearman’s r?=?0.73, P?<?0.01). Considering the increasing trend in SUV_max and TBR_max values from early to delayed imaging time-points on PET/CT and PET/MRI, respectively, with continuous clearance of radioactivity from the blood, a slight underestimation of TBR_max values may also be expected with PET/MRI compared with PET/CT.

Conclusion

SUV_max and TBR_max values are widely accepted reference parameters for estimation of the radioactivity of atherosclerotic plaques on PET/CT. However, due to a systematic underestimation of SUV_max and TBR_max with PET/MRI, the optimal cut-off values indicating the presence of inflamed plaque tissue need to be newly defined for PET/MRI.

     

Higher reliability of 18F-FDG target background ratio compared to standardized uptake value in vulnerable carotid plaque detection: a pilot study

Objective

To evaluate the role of [18F]-fluorodeoxyglucose positron emission tomography/computer tomography [18F-FDG PET/CT] comparing target background ratio (TBR) and standardized uptake value (SUV) with the histopathological inflammatory status of the carotid plaques.

Background

Vulnerable carotid plaques are the primary cause of acute cerebrovascular events. 18F-FDG PET/CT represents a morpho-functional technique able to identify the highly inflamed and most vulnerable carotid plaques. Several literature studies experimented this new method to identify vascular inflammation, but few have effectively compared PET/CT results with plaque histological data and no studies had directly compared TBR to SUV.

Methods

Thirty-two consecutive patients (20 men and 12 women, mean age 74 ± 8 years) undergoing carotid endarterectomy were enrolled and studied with carotid 18F-FDG PET/CT. Maximum and mean SUV and TBR were used to quantify 18F-FDG uptake while surgical specimens were analyzed by optical microscopy to identify inflamed carotid plaques, with evaluation of macrophages infiltration by mean of immunohistochemistry. On the basis of the presence of inflammation at the histological analysis, we divided population in two groups: group A (n = 12) patients with inflamed carotid plaques and group B (n = 20) patients with non-inflamed ones, then crossed and evaluated the histological data with 18F-FDG PET/CT findings.

Results

SUV max and SUV mean values resulted higher in group A (respectively, 2.14 ± 0.77 and 1.99 ± 0.68) than in group B (respectively, 1.79 ± 0.37 and 1.64 ± 0.34) without reaching a statistical significance (p = ns). TBR max and TBR mean values resulted higher in group A (respectively, 1.42 ± 0.32 and 1.34 ± 0.26) than in group B (respectively, 1.16 ± 0.19 and 1.03 ± 0.20) with a statistically significant differences between the two groups and carotid inflammation (respectively, p < 0.01 and p < 0.001).

Conclusion

TBR (max and mean values) is a more reliable parameter than SUV in identifying inflamed plaques. Although limited by the small population analyzed, our results suggest the important role of 18F-FDG PET/CT, using TBR, in identification of high-risk carotid atherosclerotic plaques.     

Wall morphology,blood flow and wall shear stress: MR findings in patients with peripheral artery disease

Objectives

To investigate the influence of atherosclerotic plaques on femoral haemodynamics assessed by two-dimensional (2D) phase-contrast (PC) magnetic resonance imaging (MRI) with three-directional velocity encoding.

Methods

During 1 year, patients with peripheral artery disease and an ankle brachial index <1.00 were enrolled. After institutional review board approval and written informed consent, 44 patients (age, 70?±?12 years) underwent common femoral artery MRI. Patients with contra-indications for MRI were excluded. Sequences included 2D time-of-flight, proton-density, T1-weighted and T2-weighted MRI. Electrocardiogram (ECG)-gated 2D PC-MRI with 3D velocity encoding was acquired. A radiologist classified images in five categories. Blood flow, velocity and wall shear stress (WSS) along the vessel circumference were quantified from the PC-MRI data.

Results

The acquired images were of good quality for interpretation. There were no image quality problems related to poor ECG-gating or slice positioning. Velocities, oscillatory shear stress and total flow were similar between patients with normal arteries and wall thickening/plaque. Patients with plaques demonstrated regionally increased peak systolic WSS and enhanced WSS eccentricity.

Conclusions

Combined multi-contrast morphological imaging of the peripheral arterial wall with PC-MRI with three-directional velocity encoding is a feasible technique. Further study is needed to determine whether flow is an appropriate marker for altered endothelial cell function, vascular remodelling and plaque progression.

Key Points

? Femoral plaques are associated with altered dynamics of peripheral blood flow. ? Multi-contrast MRI can investigate the presence and type of atherosclerotic plaques. ? Three-dimensional velocity-encoding phase-contrast MRI can investigate flow and wall shear stress. ? Atherosclerotic peripheral arteries demonstrate increased systolic velocities and wall shear stress.     

Comprehensive assessment of spotty calcifications on computed tomography angiography: Comparison to plaque characteristics on intravascular ultrasound with radiofrequency backscatter analysis

Background

The purpose of the study was to systematically compare calcification patterns in plaques on computed tomography angiography (CTA) with plaque characteristics on intravascular ultrasound with radiofrequency backscatter analysis (IVUS-VH).

Methods and Results

In total, 108 patients underwent CTA and IVUS-VH. On CTA, calcification patterns in plaques were classified as non-calcified, spotty or dense calcifications. Plaques with spotty calcifications were differentiated into small spotty (<1 mm), intermediate spotty (1-3 mm) and large spotty calcifications (≥3 mm). Plaque characteristics deemed more high-risk on IVUS-VH were defined by % necrotic core (NC) and presence of thin cap fibroatheroma (TCFA). Overall, 300 plaques were identified both on CTA and IVUS-VH. % NC core was significantly higher in plaques with small spotty calcifications as compared to non-calcified plaques (20% vs 13%, P = .006). In addition, there was a trend for a higher % NC in plaques with small spotty calcifications than in plaques with intermediate spotty calcifications (20% vs 14%, P = .053). Plaques with small spotty calcifications had the highest % TCFA as compared to large spotty and dense calcifications (31% vs 9% and 31% vs 6%, P < .05).

Conclusion

Plaques with small spotty calcifications on CTA were related to plaque characteristics deemed more high-risk on IVUS-VH. Therefore, CTA may be valuable in the assessment of the vulnerable plaque.     

Diagnostic accuracy and patient acceptance of MRI in children with suspected appendicitis

Objective

To compare magnetic resonance imaging (MRI) and ultrasound in children with suspected appendicitis.

Methods

In a single-centre diagnostic accuracy study, children with suspected appendicitis were prospectively identified at the emergency department. All underwent abdominal ultrasound and MRI within 2 h, with the reader blinded to other imaging findings. An expert panel established the final diagnosis after 3 months. We evaluated the diagnostic accuracy of three imaging strategies: ultrasound only, conditional MRI after negative or inconclusive ultrasound, and MRI only. Significance between sensitivity and specificity was calculated using McNemar’s test statistic.

Results

Between April and December 2009 we included 104 consecutive children (47 male, mean age 12). According to the expert panel, 58 patients had appendicitis. The sensitivity of MRI only and conditional MRI was 100 % (95 % confidence interval 92–100), that of ultrasound was significantly lower (76 %; 63–85, P?<?0.001). Specificity was comparable among the three investigated strategies; ultrasound only 89 % (77–95), conditional MRI 80 % (67–89), MRI only 89 % (77–95) (P values 0.13, 0.13 and 1.00).

Conclusion

In children with suspected appendicitis, strategies with MRI (MRI only, conditional MRI) had a higher sensitivity for appendicitis compared with a strategy with ultrasound only, while specificity was comparable.

Key Points

? In children, MRI has a higher sensitivity for appendicitis than ultrasound. ? Ultrasound followed by MRI in negative or inconclusive findings is accurate. ? The tolerance for ultrasound and MRI in children is comparable. ? MRI can be performed in children in an emergency setting.     

Fragmentation of calcified plaque after carotid artery stenting in heavily calcified circumferential stenosis

Introduction

We assessed the morphological change of calcified plaque after carotid artery stenting (CAS) in vessels with heavily calcified circumferential lesions and discuss the possible mechanisms of stent expansion in these lesions.

Methods

We performed 18 CAS procedures in 16 patients with severe carotid artery stenosis accompanied by plaque calcification involving more than 75% of the vessel circumference. All patients underwent multidetector-row computed tomography (MDCT) to evaluate lesion calcification before and within 3 months after intervention. The angiographic outcome immediately after CAS and follow-up angiographs obtained 6 months post-CAS were examined.

Results

The preoperative mean arc of the calcifications was 320.1?±?24.5° (range 278–360°). In all lesions, CAS procedures were successfully carried out; excellent dilation with residual stenosis ≤30% was achieved in all lesions. Post-CAS MDCT demonstrated multiple fragmentations of the calcifications in 17 of 18 lesions (94.4%), but only cracks in the calcified plaque without fragmentation in one (5.6%). Angiographic study performed approximately 6 months post-CAS detected severe restenosis in one lesion (5.6%) without fragmentation of calcified plaque.

Conclusions

Excellent stent expansion may be achieved and maintained in heavily calcified circumferential carotid lesions by disruption and fragmentation of the calcified plaques.     

Evaluation of distal turbulence intensity for the detection of both plaque ulceration and stenosis grade in the carotid bifurcation using clinical Doppler ultrasound

Objectives

To determine the interrelationship of stenosis grade and ulceration with distal turbulence intensity (TI) in the carotid bifurcation measured using conventional clinical Doppler ultrasound (DUS) in vitro, in order to establish the feasibility of TI as a diagnostic parameter for plaque ulceration.

Methods

DUS TI was evaluated in a matched set of ulcerated and smooth-walled carotid bifurcation phantoms with various stenosis severities (30, 50, 60 and 70 %), where the ulcerated models incorporated a type 3 ulceration.

Results

Post-stenotic TI was significantly elevated owing to ulceration in the mild and moderate stenoses (P?<?0.001). TI increased with stenosis severity in both the ulcerated and non-ulcerated series, with a statistically significant effect of increasing stenosis severity (P?<?0.001). Whereas TI in the mild and non-ulcerated moderate stenoses was less than 20.4?±?1.3 cm s^?1, TI in the ulcerated moderate and severe models was higher than 25.6 ±1.3 cm s^?1, indicating a potential diagnostic threshold.

Conclusion

We report a two-curve relationship of stenosis grade and ulceration to distal TI measured using clinical DUS in vitro. Clinical DUS measurement of distal TI may be a diagnostic approach to detecting ulceration in the mild and moderately stenosed carotid artery.

Key Points

? Patients with carotid artery plaque ulcerations are at higher risk of stroke. ? Clinical Doppler ultrasound is routinely used to detect carotid artery stenosis. ? Doppler ultrasound turbulence intensity can detect ulceration in realistic flow models. ? Turbulence intensity also increases with stenosis severity independent of ulceration. ? Doppler ultrasound should help in assessing both stenosis severity and ulceration.     

Quantification and characterisation of coronary artery plaque volume and adverse plaque features by coronary computed tomographic angiography: a direct comparison to intravascular ultrasound

Objective

We evaluated the performance of manual measures of coronary plaque volumes and atherosclerotic plaque features from coronary CT angiography (CTA), using intravascular ultrasound (IVUS) as the reference.

Methods

Thirty individual coronary plaques with suitable fiduciary markers were identified. Plaque volumes on coronary CTA were manually quantified by two observers and compared to IVUS plaque volumes as interpreted by an independent laboratory. The presence of adverse plaque characteristics—low attenuation plaque (LAP), positive remodelling (PR) and spotty calcification (SC)—on coronary CTA was evaluated and compared to IVUS.

Results

High correlation in plaque volumes was detected between observers (r?=?0.94, P?<?0.0001; 95 % limits of agreement <48.7 mm³, bias 6.6 mm³). Excellent correlation (r?=?0.95, P?<?0.0001) was noted in plaque volume between independent observers and IVUS (95 % limits of agreement <40.6 mm³, bias ?4.4 mm³) and did not differ from IVUS (105.0?±?56.7 vs. 109.4?±?60.7 mm³, P?=?0.2). The frequency of LAP (10 % vs. 17 %), PR (7 % vs. 10 %) and SC (27 % vs. 33 %) was similar between coronary CTA and IVUS (all P?=?NS).

Conclusions

Plaque volume on coronary CTA determined by manual methods demonstrates high correlation and modest agreement to IVUS. Further, coronary CTA demonstrates high accuracy for the identification of adverse plaque characteristics, including LAP, PR and SC.

Key Points

? Coronary CT angiography is a non-invasive test that enables coronary plaque assessment ? Plaque quantification by coronary CT angiography correlates well with intravascular ultrasound findings ? Coronary CT angiography can identify adverse plaque characteristics     

In vivo and in vitro evidence that 99mTc-HYNIC-interleukin-2 is able to detect T lymphocytes in vulnerable atherosclerotic plaques of the carotid artery

Purpose

Recent advances in basic science have established that inflammation plays a pivotal role in the pathogenesis of atherosclerosis. Inflammatory cells are thought to be responsible for the transformation of a stable plaque into a vulnerable one. Lymphocytes constitute at least 20 % of infiltrating cells in these vulnerable plaques. Therefore, the interleukin-2 (IL-2) receptor, being overexpressed on activated T lymphocytes, may represent an attractive biomarker for plaque vulnerability. The aim of this study was to evaluate the specificity of radiolabelled IL-2 [^99mTc-hydrazinonicotinamide (HYNIC)-IL-2] for imaging the lymphocytic infiltration in carotid plaques in vivo by planar and single photon emission computed tomography (SPECT)/CT imaging and ex vivo by microSPECT and autoradiography.

Methods

For the in vivo study, ten symptomatic patients with advanced plaques at ultrasound who were scheduled for carotid endarterectomy underwent ^99mTc-HYNIC-IL-2 scintigraphy. The images were analysed visually on planar and SPECT images and semi-quantitatively on SPECT images by calculating target to background (T/B) ratios. After endarterectomy, immunomorphological evaluation and immunophenotyping were performed on plaque slices. For the ex vivo studies, four additional patients were included and, after in vitro incubation of removed plaques with ^99mTc-HYNIC-IL-2, autoradiography was performed and microSPECT images were acquired.

Results

Visual analysis defined clear ^99mTc-HYNIC-IL-2 uptake in seven of the ten symptomatic plaques. SPECT/CT allowed visualization in eight of ten. A significant correlation was found between the number of CD25+ lymphocytes and the total number of CD25+ cells in the plaque and the T/B ratio with adjacent carotid artery as background (Pearson’s r?=?0.89, p?=?0.003 and r?=?0.87, p?=?0.005, respectively). MicroSPECT imaging showed clear ^99mTc-HYNIC-IL-2 uptake within the plaque wall and not in the lipidic core. With autoradiography, only CD3+ lymphocytes were found to be labelled.

Conclusion

These in vivo and ex vivo studies confirm the specificity of ^99mTc-HYNIC-IL-2 for imaging activated T lymphocytes in carotid plaques. ^99mTc-HYNIC-IL-2 is a true marker for the inflamed plaque and therefore of plaque instability.     

Salvage assessment with cardiac MRI following acute myocardial infarction underestimates potential for recovery of systolic strain

Objectives

Our aim was to evaluate the relationship between the degree of salvage following acute ST elevation myocardial infarction (STEMI) and subsequent reversible contractile dysfunction using cardiac magnetic resonance (CMR) imaging.

Methods

Thirty-four patients underwent CMR examination 1–7 days after primary percutaneous coronary intervention (PPCI) for acute STEMI with follow-up at 1 year. The ischaemic area-at-risk (AAR) was assessed with T2-weighted imaging and myocardial necrosis with late gadolinium enhancement. Myocardial strain was quantified with complementary spatial modulation of magnetisation (CSPAMM) tagging.

Results

Ischaemic segments with poor (<25 %) or intermediate (26–50 %) salvage index were associated with worse Eulerian circumferential (Ecc) strain immediately post-PPCI (?9.1 %?±?0.6, P?=?0.033 and ?11.8 %?±?1.3, P?=?0.003, respectively) than those with a high (51–100 %) salvage index (?14.4 %?±?1.3). Mean strain in ischaemic myocardium improved between baseline and follow-up (?10.1 %?±?0.5 vs. ?16.2 %?±?0.5 %, P?<?0.0001). Segments with poor salvage also showed an improvement in strain by 1 year (?9.1 %?±?0.6 vs. ?15.3 %?±?0.6, P?=?0.033) although they remained the most functionally impaired.

Conclusions

Partial recovery of peak systolic strain following PPCI is observed even when apparent salvage is less than 25 %. Late gadolinium enhancement (LGE) may not equate to irreversibly injured myocardium and salvage assessment performed within the first week of revascularisation may underestimate the potential for functional recovery.

Key Points

? MRI can measure how much myocardium is damaged after a heart attack. ? Heart muscle that appears initially non-viable may sometimes partially recover. ? Enhancement around the edges of infarcts may resolve over time. ? Evaluating new cardio-protective treatments with MRI requires appreciation of its limitations.     

Association between carotid plaque enhancement shown by multidetector CT angiography and histologically validated microvessel density

Purpose

Carotid plaques analysed by MDCTA can show contrast enhancement. The purpose of this study was to explore the association between carotid plaque enhancement (CPE) and microvessel density.

Materials and methods

We obtained IRB approval. Twenty-nine consecutive (male, 20; median age, 63) symptomatic patients studied with 16-detector CT were prospectively analysed. Examinations were performed before and after intravenous contrast medium administration, and analysis of plaque enhancement was performed. Patients underwent “en bloc” carotid endarterectomy; histological sections were prepared and the presence of microvessels quantified. Logistic regression analysis as well as ROC curve and area under the curve was calculated.

Results

A statistically significant association between the degree of CPE and microvessel density (P?=?0.009; rho?=?0.553) was observed. The ROC curve analysis confirmed this association with an area under the curve of 0.906, 0.735, 0.644 and 0.546 for CPE of 10 HU, 15 HU, 20 HU and 25 HU respectively. There was a statistically significant difference between the CPE and the degree of neovascularisation (P?=?0.0003).

Conclusion

Results of this preliminary study suggest that CPE might be associated with the microvessel density. Histological analysis seems to demonstrate that the degree of intra-plaque neo-vascularisation is statistically associated with CPE.

Key Points

• Carotid artery plaque enhancement at CT is associated with microvessel density.
• The degree of intra-plaque neo-vascularisation is statistically associated with carotid plaque enhancement.
• Plaque enhancement at CT should be considered when assessing vulnerable plaques.

     

Wall shear stress distribution at the carotid bifurcation: influence of eversion carotid endarterectomy

Objectives

To test the feasibility of four-dimensional (4D) flow MRI to quantify the systolic wall shear stress (WSS_systole) and oscillatory shear index (OSI) in high-grade internal carotid artery (ICA) stenosis before and after endarterectomy (CEA).

Methods

Twenty patients with ≥60 % ICA stenosis were prospectively and consequently included. Four-dimensional flow MRI was used to measure individual time-resolved 3D blood flow velocities. Segmental WSS_systole and OSI were derived at eight wall segments in analysis planes positioned along the ICA, common (CCA) and external carotid artery (ECA).

Results

Regional WSS_systole of all patients decreased after CEA (P?<?0.05). Changes were most prominent at the ICA bulb but remained unchanged in the CCA and ECA. OSI was significantly lower after CEA in the lateral vessel walls (P?<?0.05). For analysis planes at the stenosis in- and outlet, a reduction of mean WSS_systole by 32 % and 52 % (P?<?0.001) and OSI distal to the stenosis (40 %, P?=?0.01) was found after CEA.

Conclusions

Our findings show the potential of in vivo 4D flow MRI to quantify haemodynamic changes in wall shear stress even in patients with complex flow conditions.

Key Points

? The 4D flow MRI allows in vivo measurement of individual 3D blood flow. ? Regional wall shear stress can be derived from such 3D flow data. ? Even complex flow in high-grade internal carotid artery stenosis can be analysed. ? This technique could be valuable for future studies of carotid atherosclerosis.     

Abdominal fat distribution and carotid atherosclerosis in a general population: a semi-automated method using magnetic resonance imaging

Purpose

Available evidence suggests functional differences in visceral and subcutaneous fat. We investigated the association between quantitative measures of central adiposity with indicators of carotid atherosclerosis including intima-media thickness (IMT) and plaque in a general population using a semi-automated method on magnetic resonance imaging (MRI) data.

Methods

In this cross-sectional study 200 subjects (52 % female), aged 50–77 years, were randomly selected from Golestan Cohort Study. Participants underwent ultrasound examination of carotid arteries and abdominal MRI. Segmentation and calculation of visceral (VFA) and subcutaneous fat area (SFA) were performed on three levels using semi-automated software. Various conventional anthropometric indices were also measured.

Results

Among 191 enrolled subjects, 77 (40 %) participants had IMT ≥0.8 mm. Carotid plaques were detected in 86 (44 %) subjects. In separate multivariate analysis models, unlike SFA and other anthropometric indices, the last tertile of VFA values was associated with at least threefold excess risk for IMT ≥0.8 mm (OR 3.8, 95 % CI 1.36–6.94, p = 0.02). There was no significant difference between mean values of categorized obesity indices in subjects with and without plaque, while participants in the highest tertile of VFA values were demonstrated to have higher risk of more than one plaque (OR 4.57, 95 % CI 1.03–20.11, p = 0.034).

Conclusions

A higher amount of visceral fat, measured by a semi-automated technique using MRI, is associated with increased IMT and having more than one carotid plaque in a general population, while subcutaneous fat measures are poor indicators for identifying carotid atherosclerosis.

     

Integrated non-invasive approach to atherosclerosis with cardiac CT and carotid ultrasound in patients with suspected coronary artery disease

Objective

The aim of the study was to compare the atherosclerotic disease in the coronary and carotid arteries in patients who underwent non-invasive imaging for suspected stable coronary artery disease (CAD).

Materials and methods

107 patients (64 men, age 59 ± 12) with atypical chest pain underwent cardiac CT (CCT) and carotid ultrasound (US) on the same day. Severity (obstructive or not-obstructive disease), location, shape, and composition of atherosclerotic plaques in the two districts were evaluated.

Results

Patients presented normal coronary arteries in 36 % (n = 38), not-obstructive CAD in 36 % (n = 39), and obstructive CAD in 28 % (n = 30), while had normal carotid arteries in 53 % (n = 57), not-obstructive disease in 44 % (n = 47), and obstructive disease in 3 % (n = 3) (p < 0.05). The coronary plaques were located in 7 % at ostial sites, in 29 % at non-ostial sites, and in 64 % at both locations. The carotid plaques were located at the origin of the internal and external carotid arteries in 56 %, at the bifurcation in 20 %, and at both locations in 24 % (p < 0.05). Coronary plaques were calcified in 25 %, non-calcified in 19 %, and mixed in 56 %; carotid plaques were calcified in 8 %, non-calcified in 8 %, and mixed in 84 % of patients (p < 0.05).

Conclusion

Atherosclerotic disease presents different imaging findings in the coronary tree and in the carotid district with respect to lesion severity, position along the vessel course, and composition of plaque.

     

Imaging of inflamed carotid artery atherosclerotic plaques with the use of 99mTc-HYNIC-IL-2 scintigraphy in end-stage renal disease patients

Purpose

Identification of vulnerable plaques remains crucial for better cardiovascular risk assessment. At least 20% of inflammatory cells within unstable (vulnerable) plaques comprise T lymphocytes, which contain receptors for interleukin-2 (IL-2); those receptors can be identified by scintigraphy with radiolabelled IL-2.The aim of this study was to identify the “inflamed” (vulnerable) plaques by scintigraphy using IL-2 labelled with ^99mTc in the selected, high cardiovascular risk group of end-stage renal disease (ESRD) patients.

Methods

A total of 28 patients (18 men, 10 women, aged 55.2?±?9.6?years, 17 on peritoneal dialysis, 11 on haemodialysis) underwent common carotid artery (CCA) scintigraphy with the use of ^99mTc-hydrazinonicotinamide (HYNIC)-IL-2. In all cases, ultrasound examination of the CCA was performed and levels of selected proinflammatory factors, atherogenic markers and calcium-phosphate balance parameters were measured. Finally, the target to non-target (T/nT) ratio of IL-2 uptake in atherosclerotic plaques with intima-media thickness (IMT), classic cardiovascular risk factors and concentrations of the measured factors were compared.

Results

Increased ^99mTc-HYNIC-IL-2 uptake in atherosclerotic plaques in 38/41 (91%) cases was detected. The median T/nT ratio of focal ^99mTc-HYNIC-IL-2 uptake in atherosclerotic plaques was 2.35 (range 1.23–3.63). The mean IMT value on the side of plaques assessed by scintigraphy was 0.79?±?0.18?mm (median 0.8, range 0.5–1.275). Correlations between T/nT ratio and homocysteine (R?=?0.22, p?=?0.037), apolipoprotein B (apoB) (R?=?0.31, p?=?0.008), apoB to apoA-I ratio (R?=?0.29, p?=?0.012) and triglyceride concentration (R?=?0.26, p?=?0.021) were detected. A lower T/nT ratio in patients with better parameters of nutritional status (haemoglobin, albumin, adiponectin) in comparison with patients with worse nutritional parameters (3.20?±?0.5 vs 2.16?±?0.68, p?=?0.025) was revealed as well as a difference between values of T/nT ratio in groups of patients with values of apoB, soluble CD40 ligand and asymmetric dimethylarginine above and below median (3.18?±?0.52 vs 2.16?±?0.68, p?=?0.031). No statistically significant association was found between T/nT ratio and mean value of either IMT or classic cardiovascular risk factors.

Conclusion

Scintigraphy with the use of ^99mTc-HYNIC-IL-2 can be a tool for inflamed atherosclerotic (vulnerable) plaque visualization within CCA in ESRD patients. Quantitative results of carotid artery scintigraphy with ^99mTc-HYNIC-IL-2 correlate with serum concentration of selected cardiovascular risk markers.