CORE Metadata, citation and similar papers at core.ac.uk

Provided by Elsevier - Publisher Connector

From the Society for

High-resolution magnetic resonance imaging of carotid identifies vulnerable carotid plaques

Antoine Millon, MD,a Jean-Louis Mathevet, MD,a Loic Boussel, MD, PhD,b Peter L. Faries, MD,c Zahi A. Fayad, PhD,d Philippe C. Douek, MD, PhD,b and Patrick Feugier, MD, PhD,a Lyon, France; and New York, NY

Objective: Carotid magnetic resonance imaging (MRI) may be a useful tool in characterizing carotid plaque vulnerability, but large studies are still lacking. The purpose of this study was to assess carotid MRI features of vulnerable plaque in a large study and the changes in carotid plaque morphology with respect to time since the neurological event. Methods: We included 161 patients with carotid plaque more than 3 mm thick. All patients underwent carotid MRI to obtain 3-T high-resolution magnetic resonance sequences. Large lipid core, intraplaque hemorrhage (IPH), fibrous cap rupture (FCR), and gadolinium enhancement (GE) were assessed and classified as present or absent. Prevalences of these features were then compared between symptomatic and asymptomatic patients and time since . Results: Seven patients were excluded because of poor image quality. Of the remaining 154 patients, 52 were symptomatic and 102 were asymptomatic. The prevalences of IPH (39 vs 16%; P [ .002), FCR (30 vs 9%; P [ .001), and GE (75 vs 55%; P [ .015) were significantly higher in symptomatic than asymptomatic patients. After multivariate analysis, the prevalences of IPH (odds ratio, 2.6; P [ .023) and FCR (odds ratio, 2.8; P [ .038) were still significantly higher. The prevalence of IPH was significantly higher in symptomatic patients with plaque regardless of the time since the neuro- logical event. For FCR, the difference between symptomatic and asymptomatic patients was significant only during the first 15 days after the neurological event. Conclusions: Carotid MRI can identify plaque features that are associated with symptomatic presentation and may be indicative of plaque vulnerability. These features may ultimately be used in the management of extracranial carotid . (J Vasc Surg 2013;57:1046-51.)

The benefit of carotid or carotid - symptomatic patients with carotid plaque, Redgrave et al ing for asymptomatic extracranial carotid stenosis is increas- reported high prevalences of fibrous cap rupture, large lipid ingly being questioned. The average expected annual core, dense macrophage infiltrate, and, to a lesser extent, ipsilateral stroke rate among hospital-referred patients with intraplaque hemorrhage.3 At the same time, accurate in vivo asymptomatic severe carotid stenosis receiving current morphological and functional characterization of the carotid medical intervention alone is now around 1%.1,2 Therefore, has greatly improved, especially since the develop- stratification of patients at “high risk for stroke” is necessary ment of high-resolution magnetic resonance imaging (HR- to improve patient selection for interventional therapies, and MRI). Histological correlation studies have demonstrated carotid plaque characterization may help achieve this. the ability of in vivo HR-MRI to detect characteristics of Vulnerable or prone-to-rupture carotid plaque has vulnerable plaque with a high degree of sensitivity and speci- been defined by extension with coronary artery disease ficity.4-7 Some studies have already demonstrated that these through histological studies. In a histological study of 526 features are significantly more frequent in symptomatic patients.8-10 However, most of these studies have been fl From the Department of Vascular Surgery, University Hospital of Lyon,a performed on small numbers of patients. In ammation, and the Department of , Hôpital Cardiovasculaire et Pneumo- a well-known factor in plaque destabilization, can also be logique Louis Pradel,b Lyon; and the Division of Vascular Surgery, assessed by HR-MRI as gadolinium enhancement in the Mount Sinai Hospital,c and the Translational and 11-13 d plaque, but very few studies report this feature. Institute, Mount Sinai School of Medicine, New York. Plaque vulnerability is defined by the high risk of occur- Author conflict of interest: none. Presented at the 2012 Vascular Annual Meeting of the Society of Vascular rence of a neurological event. It is well known that there is Surgery, Washington, DC, June 7-9, 2012, during Rapid Paced Paper a high risk of stroke recurrence in the first 15 days after Session II. a stroke. Therefore, we can assume that plaque is highly Additional material for this article may be found online at www.jvascsurg.org. unstable during this period. Accordingly, the present Reprint requests: Antoine Millon, MD, Department of Vascular Surgery, Hospital E Herriot, Place d’Arsonval, 69003 Lyon, France (e-mail: study investigated the ability of 3-T HR-MRI to determine [email protected]). features of plaque vulnerability such as large lipid-rich The editors and reviewers of this article have no relevant financial relationships necrotic core, fibrous cap rupture, intraplaque hemorrhage, to disclose per the JVS policy that requires reviewers to decline review of any and gadolinium enhancement in carotid plaques in a large fl manuscript for which they may have a con ict of interest. number of symptomatic and asymptomatic patients and 0741-5214/$36.00 Copyright Ó 2013 by the Society for Vascular Surgery. the distribution of these features with time since the neuro- http://dx.doi.org/10.1016/j.jvs.2012.10.088 logical event.

1046 JOURNAL OF VASCULAR SURGERY Volume 57, Number 4 Millon et al 1047

METHODS with an 18-cm field of view. In cases of detection > Study population. The institutional review board of bilateral plaque 3 mm thick, the largest plaque was approved the consent form and study protocols. Participants considered of interest if the patient was asymptomatic or the were identified among inpatients; outpatients were eligible symptomatic side (regardless of thickness) if the patient was for the study if they had carotid plaque thicker than 3 mm symptomatic. detected by ultrasonography (as it is known that patients Image review. Prior to quantitative analysis, all images with thick carotid plaque may have a high risk of stroke were reviewed to assess image quality. Images with scores ¼ ¼ even if they do not have severe stenosis) and had no lower than 2 on a 5-point scale (0 not assessable, 1 ¼ ¼ ¼ contraindications to MRI (heart pacemaker, metallic poor, 2 moderate, 3 good, 4 excellent) depending implant, severe claustrophobia) or intravenous injection of on the signal-to-noise ratio were excluded from the anal- gadolinium (pregnancy, allergy, glomerular filtration ysis. Two experienced observers (L.B., A.M.) blinded to rate <30 mL/min). A neurologist or a vascular surgeon the clinical history analyzed the magnetic resonance images fi experienced in carotid pathology recorded clinical data, and reached a consensus. The observers identi ed the lipid- fi including history of cardiovascular disease, risk factors for rich necrotic core (LC) and brous cap (FC) based on the atherosclerosis, medical treatment, neurological event signal intensity for each sequence. Fibrous cap rupture (stroke, transient ischemic attack, or amaurosis), and time (FCR), intraplaque hemorrhage (IPH), and gadolinium between neurological event and HR-MRI. Stroke etiology enhancement (GE) in the carotid plaque were also assessed was determined with a workup based on an imaging package according to previously published criteria (Appendix, $ including one or more of the following examinations as online only). IPH, FCR, large LC ( 50%), and GE were fi requested for normal patient care: duplex ultrasound classi ed as present or absent. imaging, magnetic resonance or computed Statistical analysis. Statistical analysis was performed angiography of the neck and brain vessels, and with SPSS Version 15.0 (SPSS, Chicago, Ill). Continuous transthoracic or transesophageal . Patients variables were expressed as means and standard deviations with a recent stroke related to a cardiac source, including or ranges. Categorical variables were expressed as frequen- atrial fibrillation, intracardiac thrombus, and patent foramen cies and percentages. Univariate analysis was performed c2 ovale, were excluded from this study. Biological data using a test for categorical variables and a t-test for including inflammation markers (ultrasensitive C-reactive continuous variables. protein [usCRP], fibrinogen) were recorded. In addition to Multivariate analysis was performed using binary plaque thickness measurement, carotid ultrasonography was logistic regression models with plaque causing symptoms used to assess the degree of stenosis according to the North in patients as the dependent variable and plaque features American Symptomatic Trial (IPH, FCR, large LC, and GE) as independent variables. < (NASCET) criteria. This population was divided into two Variables with P .10 in univariate analysis were entered < groups: asymptomatic without any neurological events into the models. P .05 were considered statistically fi during the past 6 months, and symptomatic with an ipsi- signi cant. lateral carotid-related neurological event during the past 6 months. Symptomatic patients were subdivided into two RESULTS subgroups on the basis of time between the neurological We included 161 patients seen from January 2010 to event and HR-MRI (acutely symptomatic patients, <15 November 2011 with carotid plaque thicker than 3 mm days; recently symptomatic patients, 15-180 days). thick. All patients underwent HR-MRI. Seven (4.3%) MRI protocol. Imaging was performed using a 3-T patients were excluded because of poor image quality HR-MRI system (Achieva scanner; Philips Healthcare, related to motion artifact (five cases), metallic dental Best, The Netherlands) with a dual-surface coil (Sense Flex implant (one case), and incomplete scan caused by claus- S; Philips Healthcare) positioned on top of the mandibular trophobia (one case). Among the 154 remaining patients, angles. This coil was combined with a head holder to 52 (33%) were symptomatic: 41 , seven transient stabilize position and prevent head rotation. A standardized ischemic attacks (TIAs), and four cases of amaurosis. magnetic resonance protocol was used. After a survey to Origin of carotid plaque was de novo atherosclerostic determine the position of the carotid bifurcation of interest, disease. There was no restenosis or radiation-induced time-of-flight (TOF)-, T1-, and proton density (PD)- carotid plaque. Mean delay between symptoms and HR- weighted sequences were acquired on the plaque center and MRI was 35.8 6 41.3 days (range, 1-177). Twenty-two perpendicular to the main carotid axis. Before and after (14%) patients underwent HR-MRI within 15 days injection of gadolinium-based contrast agent (Dotarem, (acutely symptomatic patients) and 30 (19%), between 15 Guerbet, France), a three-dimensional TOF multiple and 180 days (recently symptomatic patients). overlapping thin-slab acquisition magnetic resonance Demographic characteristics, medications used, biolog- angiography (MRA) sequence was obtained followed 5 ical results, plaque thickness, and NASCET degree of minutes later by a T1-weighted sequence. Total acquisition stenosis are summarized in Table I. Symptomatic and time was approximately 45 minutes. Fat suppression was asymptomatic patients did not significantly differ with used for all sequences, and all examinations were performed respect to demographics or medications used. Diabetes JOURNAL OF VASCULAR SURGERY 1048 Millon et al April 2013

Table I. Characteristics of the population

Characteristic Symptomatic (n ¼ 5) Asymptomatic (n ¼ 102) P

Age 70 (12, 35-87)a 70 (9, 41-91)a .726 Male gender 73% 71% .746 Active smokers 31% 21% .162 Hypertension 71% 79% .252 Diabetes 21% 36% .055 Dyslipidemia 56% 61% .549 Mean body mass index 25.4 (4.1, 19.1-35.9)a 26.3 (4.1, 19.0-36.2)a .240 Coronary artery disease 17% 29% .102 Statin 75% 81% .357 Aspirin 83% 87% .444 Oral anticoagulant therapy 2% 8% .139 Ultrasensitive C-reactive protein, mg/L 12.4 (41, 0.4-287)a 5.1 (6, 0.2-35.7)a .063 Fibrinogen, g/L 4.0 (1, 2.0-9.0)a 3.9 (1, 2.4-6.8)a .709 Mean plaque thicknes, mm 5.0 (1.4, 3.0-8.3)a 4.9 (1.2, 3.0-7.5)a .293 NASCET degree of stenosis 65% (20, 0-95)a 70% (20, 0-95)a .183

NASCET, North American Symptomatic Carotid Endarterectomy Trial. aMean (standard deviation, range).

Table II. Carotid plaque features and their distribution among symptomatic and asymptomatic patients

Univariate Multivariate analysis All patients Symptomatic patients Asymptomatic patients analysis (n ¼ 154) (n ¼ 52) (n ¼ 102) P OR CI P

Intraplaque hemorrhage 36% (23.4) 2% (38.5%) 16% (15.7) .002 2.6 1.1-5.8 .023 Fibrous cap rupture 24% (15.6%) 15% (28.8%) 9% (8.8) .001 2.8 1.1-7.4 .038 Gadolinium enhancement 95% (61.7%) 39% (75.0%) 56% (54.9) .015 1.9 0.9-4.2 .098 Large lipid core 44% (28.6%) 20% (38.5%) 24% (23.5) .052 1.5 0.7-3.3 .333

CI, Confidence interval; OR, odds ratio. and coronary artery disease were more frequent in asymp- is significantly more frequent in symptomatic patients tomatic patients, and usCRP levels were higher (but not than in asymptomatic patients regardless of the time since significantly) in symptomatic patients. Mean plaque thick- stroke (P ¼ .007, acutely symptomatic patients; P ¼ ness and mean NASCET degree of stenosis were 4.9 6 .012, recently symptomatic patients). FCR is significantly 1.3 mm (3.0-8.3) and 67 6 20% (0-95%), respectively, more frequent in acutely symptomatic patients than in with no difference between symptomatic and asymptomatic asymptomatic patients, whereas its frequency does not patients. Two (1.3%) patients had no stenosis according differ between recently symptomatic and asymptomatic to NASCET criteria, and 22 (14.3%) patients had mild patients. There were no significant differences between stenosis (<50%). subgroups in large LC (P ¼ .212 for acute asymptomatic; Carotid plaque features and their distribution between P ¼ .075 for recently symptomatic vs asymptomatic symptomatic and asymptomatic patients are summarized in patients) or GE (P ¼ .053 for acutely symptomatic Table II. Prevalences of IPH, FCR, and GE were signifi- patients; P ¼ .071 for recently symptomatic vs asymptom- cantly higher in symptomatic than asymptomatic patients atic patients). after univariate analysis. Large LC was also more frequent Ninety-one (59%) patients underwent carotid endarter- in symptomatic patients but without statistical significance. ectomy (Supplementary Fig, online only). Correlation with After multivariate analysis, IPH and FCR were still signifi- histology was performed for 79 patients. The sensitivity cantly higher in symptomatic than in asymptomatic and specificity of HR-MRI in the detection of IPH, patients. Carotid plaque features were similarly distributed FCR, and large LC were respectively 71% and 97%, 70% in patients with mild (<50%), moderate (50%-70%), and and 82%, and 68% and 78%. The prevalences of neovessels, severe (>70%) stenosis, except for IPH, which was higher macrophages, and loose fibrosis in the area of GE were (but not significantly) in plaque with severe stenosis 97%, 87%, and 80%. (Table III). We did not observe any difference in terms of patient characteristics or plaque features during the DISCUSSION study period (results provided in the Supplementary Finding reproducible and reliable criteria to identify Table, online only). carotid plaque at high risk of inducing stroke is key to After analysis of carotid plaque composition with improving management of asymptomatic carotid stenosis. respect to time since stroke (Fig), we observed that IPH Our study confirms the ability of high-resolution MRI to JOURNAL OF VASCULAR SURGERY Volume 57, Number 4 Millon et al 1049

Table III. Carotid plaque features with respect to NASCET degree of stenosis

Absent/mild stenosis, <50% Moderate stenosis, 50-70% Severe stenosis, >70% (n ¼ 34)a (n ¼ 42)a (n ¼ 7)a P

Intraplaque hemorrhage 6 (18) 6 (14) 24 (31) .084 Fibrous cap rupture 5 (15) 5 (12) 14 (18) .676 Gadolinium enhancement 22 (65) 24 (57) 49 (63) .763 Large lipid core 12 (35) 10 (24) 22 (28) .542

NASCET, North American Symptomatic Carotid Endarterectomy Trial. aNumber (%).

fibrous cap have been proposed. To improve the reliability of fibrous cap characterization, we chose the combination of TOF- and post-gadolinium T1-weighted sequences (Supplementary Fig, online only). Consistent with previ- ously published data we confirmed, in a large cohort of patients, the higher prevalence of FCR in symptomatic patients.8-10,17-19 We also showed that this difference exists for acutely symptomatic patients, but it disappears for symptomatic patients 15 days after stroke, probably because of a healing process. These results confirm histo- logical data and a recent study using HR-MRI and high- light the accuracy of MRI in detecting different stages of Fig. Carotid plaque composition with time since stroke. FC, plaque in symptomatic patients.3,20 Fibrous cap; GE, gadolinium enhancement; IP, intraplaque; LC, The role of IPH in atherosclerotic disease progression lipid-rich necrotic core. and cerebrovascular events has recently attracted serious interest.21 MRI-histopathology correlation studies have identify high-risk carotid plaque and to differentiate symp- shown that IPH can be detected with HR-MRI with good tomatic from asymptomatic patients. The prevalences of accuracy and high specificity and sensitivity.4,22,23 Our IPH, FCR, and inflammation (GE) identified on MRI results confirm the relationship between the presence of were significantly higher in symptomatic than in asymptom- IPH and the occurrence of clinical cerebral events and are atic patients. The prevalences of IPH and FCR were still consistent with recent studies.17,24,25 Turc et al26 recently significantly higher after multivariate analysis. The preva- reported an association between IPH and patient symp- lence of IPH was significantly higher in symptomatic toms, with a higher prevalence of IPH in patients with patients regardless of the time since stroke, whereas the more severe clinical presentations. Our findings showed prevalence of FCR was significantly higher only in acutely a significant difference between symptomatic and asymp- symptomatic patients. tomatic patients regardless of the time since stroke. This The absence of significant differences in demographic result is consistent with the Oxford Plaque Study, which characteristics and inflammatory status between asymptom- found in more than 526 symptomatic patients with carotid atic and symptomatic patients is not surprising and confirms plaque that the association between IPH and the time since the need for further investigations to identify patients at stroke was weak.3 A recent histological study reports a very high risk for stroke. We observed that diabetes and coronary high prevalence (around 70%) of IPH in carotid plaque in artery disease tend to be more frequent in asymptomatic symptomatic as well as asymptomatic patients.27 Further- than in symptomatic patients certainly because of recruit- more, two different stages of IPH have been identified: ment bias related to the systematic screening for carotid organized and amorphous.28 At the same time, it has been stenosis in this population. We also observed a trend toward reported that MRI can be used to differentiate fresh, recent, higher usCRP levels among symptomatic patients. This and old hemorrhage from the signal on TOF-, T1-, and T2- result is consistent with previous studies that reported that weighted sequences.21 The prevalence of IPH in our series, serum usCRP levels are associated with the presence of as well in other series reporting MRI findings, is much lower neurological symptoms and plaque instability in patients (around 30%-40%) than that observed during histological with carotid artery disease.14,15 Our study may be under- analysis. These discrepancies may be related to small IPH powered to show statistical significance. undetectable because of the low spatial resolution of MRI. Fibrous cap visualization using HR-MRI has already It has previously been shown that HR-MRI can quan- established good agreement with histological findings but tify LC in vivo in carotid plaque with a high correlation only with moderate reproducibility.5,6,16 Several magnetic with histology and with high specificity and sensistiv- resonance sequences and combinations have been re- ity.29,30 Our results showed a higher prevalence of large ported, and different methods for characterizing the LC in symptomatic patients, but the difference was not JOURNAL OF VASCULAR SURGERY 1050 Millon et al April 2013 statistically significant probably because of the lack with good reliability and high specificity and sensitivity. of power of the study. Cappendijk et al30 also failed to HR-MRI features of plaque vulnerability are well correlated show a statistical difference between symptomatic and with patient symptoms. Large prospective studies are asymptomatic patients, whereas Ota et al more recently re- required to confirm that criteria visualized on HR-MRI ported that large LC is associated with fibrous cap status are predictive of neurological events and that HR-MRI and, therefore, plaque vulnerability.31 Definition and allows better patient selection for interventional therapies. measurement of “large” LC are not well established and can explain this disagreement. AUTHOR CONTRIBUTIONS Carotid plaque GE related to the presence of neoves- Conception and design: AM, PF sels, infiltration of inflammatory cells, and matrix degrada- Analysis and interpretation: AM, JM, LB tion was significantly higher in symptomatic patients, 11-13,32 Data collection: AM, JLM, LB consistent with previous studies. However, the Writing the article: AM statistical significance was weak and was not any stronger after multivariate analysis. In the Oxford Plaque Study, Critical revision of the article: PF, PD, PLF, ZF Final approval of the article: AM, JM, LB, PLF, ZF, PD, PF high macrophage density was strongly associated with Statistical analysis: AM, LB FCR and time since stroke, whereas neovascularization and lymphocyte infiltration were not associated with either Obtained funding: Not applicable Overall responsibility: AM, PF FCR or time since stroke. These results may explain the weak association between patient symptoms and GE. We focused our image analysis on the most established REFERENCES fi features in terms of MRI de nition and histological correla- 1. Naylor AR. Time to rethink management strategies in asymptomatic tion. Calcification or fibrous tissue can also be identified on carotid artery disease. Nat Rev Cardiol 2011;9:116-24. MRI, but their quantification remains an issue. Moreover, it 2. Abbott AL. Medical (nonsurgical) intervention alone is now best for is still unclear whether these are features of stable or unstable prevention of stroke associated with asymptomatic severe carotid stenosis: results of a systematic review and analysis. Stroke 2009;40:e573-83. plaque. On the basis of our study, we do not know if other 3. Redgrave JN, Lovett JK, Gallagher PJ, Rothwell PM. Histological features are correlated or not with patient symptoms. assessment of 526 symptomatic carotid plaques in relation to the nature Other imaging modalities have been proposed for and timing of ischemic symptoms: the Oxford plaque study. Circula- high-risk stratification through carotid plaque characteriza- tion 2006;113:2320-8. tion. Ultrasound plaque classification based on echoluency 4. Yuan C, Mitsumori LM, Ferguson MS, Polissar NL, Echelard D, Ortiz G, et al. In vivo accuracy of multispectral magnetic resonance and the pixel grayscale value has been proposed. Grayscale imaging for identifying lipid-rich necrotic cores and intraplaque median value, plaque area, and juxtaluminal black area have hemorrhage in advanced human carotid plaques. Circulation been shown to be predictive factors in the Asymptomatic 2001;104:2051-6. Carotid Stenosis and Risk of Stroke Study.33 Despite these 5. Cai J, Hatsukami TS, Ferguson MS, Kerwin WS, Saam T, Chu B, et al. In vivo quantitative measurement of intact fibrous cap and lipid-rich results and the fact that it is widely available, is easy to use, necrotic core size in atherosclerotic carotid plaque: comparison of is less expensive than other imaging modalities, and may be high-resolution, contrast-enhanced magnetic resonance imaging and repeated as often as necessary, plaque characterization by histology. Circulation 2005;112:3437-44. carotid ultrasonography remains rarely used. A recent study 6. Hatsukami TS, Ross R, Polissar NL, Yuan C. Visualization of fibrous cap thickness and rupture in human atherosclerotic carotid plaque comparing carotid MRI, carotid ultrasonography, and fi in vivo with high-resolution magnetic resonance imaging. Circulation histopathological ndings of plaque specimens removed 2000;102:959-64. during carotid endarterectomy concluded that findings of 7. Wasserman BA, Smith WI, Trout HH III, Cannon RO III, carotid ultrasonography and MRI are closely associated Balaban RS, Arai AE. Carotid artery atherosclerosis: in vivo morpho- with carotid endarterectomy specimen morphology, but logic characterization with gadolinium-enhanced double-oblique MR fi imaging initial results. Radiology 2002;223:566-73. ultrasonography alone is insuf cient to diagnose plaque 8. Saam T, Cai J, Ma L, Cai YQ, Ferguson MS, Polissar NL, et al. 34 type accurately in some patients. Furthermore, although Comparison of symptomatic and asymptomatic atherosclerotic carotid standard carotid ultrasonography can accurately analyze plaque features with in vivo MR imaging. Radiology 2006;240:464-72. plaque surface and detect soft plaque, it does not allow 9. Sadat U, Weerakkody RA, Bowden DJ, Young VE, Graves MJ, Li ZY, fl et al. Utility of high resolution MR imaging to assess carotid plaque visualization of intraplaque hemorrhage and in ammation, morphology: a comparison of acute symptomatic, recently symptomatic both major criteria of instability. Multidetector computed and asymptomatic patients with carotid artery disease. Atherosclerosis tomography angiography could also characterize some 2009;207:434-9. vulnerable carotid plaque features in a short time and 10. U-King-Im JM, Tang TY, Patterson A, Graves MJ, Howarth S, Li ZY, with high spatial resolution. Even though it is an excellent et al. Characterisation of carotid atheroma in symptomatic and fi asymptomatic patients using high resolution MRI. J Neurol Neurosurg modality for assessing plaque ulceration and plaque calci - Psychiatry 2008;79:905-12. cation, it appears more limited in the evaluation of soft 11. Kawahara I, Morikawa M, Honda M, Kitagawa N, Tsutsumi K, tissue and requires radiation exposure. Nagata I, et al. High-resolution magnetic resonance imaging using gadolinium-based contrast agent for atherosclerotic carotid plaque. CONCLUSIONS Surg Neurol 2007;68:60-5. 12. Kerwin WS, O’Brien KD, Ferguson MS, Polissar N, Hatsukami TS, High-resolution magnetic resonance imaging is able to Yuan C. Inflammation in carotid atherosclerotic plaque: a dynamic identify all histological characteristics of vulnerable plaque contrast-enhanced MR imaging study. Radiology 2006;241:459-68. JOURNAL OF VASCULAR SURGERY Volume 57, Number 4 Millon et al 1051

13. Papini GD, Di Leo G, Tritella S, Nano G, Cotticelli B, Clemente C, imaging in symptomatic patients with mild to moderate carotid stenosis et al. Evaluation of inflammatory status of atherosclerotic carotid pla- predicts recurrent neurological events. J Vasc Surg 2008;47:337-42. que before thromboendarterectomy using delayed contrast-enhanced 26. Turc G, Oppenheim C, Naggara O, Eker OF, Calvet D, Lacour JC, subtracted images after magnetic resonance angiography. Eur J et al, for the High-Resolution Magnetic Resonance Imaging in Radiol 2011;80:e373-80. Atherosclerotic Stenosis of the Carotid Artery (HIRISC) Study Group. 14. Alvarez Garcia B, Ruiz C, Chacon P, Sabin JA, Matas M. High- Relationships between recent intraplaque hemorrhage and stroke risk sensitivity C-reactive protein in high-grade carotid stenosis: risk marker factors in patients with carotid stenosis: the HIRISC study. Arterioscler for unstable carotid plaque. J Vasc Surg 2003;38:1018-24. Thromb Vasc Biol 2012;32:492-9. 15. Papas TT, Maltezos CK, Papanas N, Kopadis G, Marakis J, Maltezos E, 27. Hellings WE, Peeters W, Moll FL, Piers SR, van Setten J, Van der et al. High-sensitivity CRP is correlated with neurologic symptoms and Spek PJ, et al. Composition of carotid atherosclerotic plaque is asso- plaque instability in patients with severe stenosis of the carotid bifur- ciated with cardiovascular outcome: a prognostic study. Circulation cation. Vasc Endovascular Surg 2008;42:249-55. 2010;121:1941-50. 16. Touzé E, Toussaint JF, Coste J, Schmitt E, Bonneville F, Vandermarcq P, 28. Derksen WJ, Peeters W, van Lammeren GW, Tersteeg C, de Vries JP, et al, for the High-Resolution Magnetic Resonance Imaging in Athero- de Kleijn DP, et al. Different stages of intraplaque hemorrhage are sclerotic Stenosis of the Carotid Artery (HIRISC) Study Group. Repro- associated with different plaque phenotypes: a large histopathological ducibility of high-resolution MRI for the identification and the study in 794 carotid and 276 femoral endarterectomy specimens. quantification of carotid atherosclerotic plaque components: consequences Atherosclerosis 2011;218:369-77. for prognosis studies and therapeutic trials. Stroke 2007;38:1812-9. 29. Saam T, Ferguson MS, Yarnykh VL, Takaya N, Xu D, Polissar NL, 17. Yuan C, Zhang SX, Polissar NL, Echelard D, Ortiz G, Davis JW, et al. et al. Quantitative evaluation of carotid plaque composition by in vivo Identification of fibrous cap rupture with magnetic resonance imaging MRI. Arterioscler Thromb Vasc Biol 2005;25:234-9. is highly associated with recent transient ischemic attack or stroke. 30. Cappendijk VC, Heeneman S, Kessels AG, Cleutjens KB, Circulation 2002;105:181-5. Schurink GW, Welten RJ, et al. Comparison of single-sequence T1W 18. Lindsay AC, Biasiolli L, Lee JM, Kylintireas I, MacIntosh BJ, Watt H, TFE MRI with multisequence MRI for the quantification of lipid-rich et al. Plaque features associated with increased cerebral infarction after necrotic core in atherosclerotic plaque. J Magn Reson Imaging minor stroke and TIA: a prospective, case-control, 3-T carotid artery 2008;27:1347-55. MR imaging study. JACC Cardiovasc Imaging 2012;5:388-96. 31. Ota H, Yu W, Underhill HR, Oikawa M, Dong L, Zhao X, et al. 19. Takaya N, Yuan C, Chu B, Saam T, Underhill H, Cai J, et al. Asso- Hemorrhage and large lipid-rich necrotic cores are independently ciation between carotid plaque characteristics and subsequent ischemic associated with thin or ruptured fibrous caps: an in vivo 3T MRI study. cerebrovascular events: a prospective assessment with MRI—initial Arterioscler Thromb Vasc Biol 2009;29:1696-701. results. Stroke 2006;37:818-23. 32. Qiao Y, Etesami M, Astor BC, Zeiler SR, Trout HH III, 20. Teng Z, Degnan AJ, Sadat U, Wang F, Young VE, Graves MJ, et al. Wasserman BA. Carotid plaque neovascularization and hemorrhage Characterization of healing following atherosclerotic carotid plaque detected by MR imaging are associated with recent cerebrovascular rupture in acutely symptomatic patients: an exploratory study using ischemic events. AJNR Am J Neuroradiol 2012;33:755-60. in vivo cardiovascular magnetic resonance. J Cardiovasc Magn Reson 33. Nicolaides AN, Kakkos SK, Kyriacou E, Griffin M, Sabetai M, Thomas DJ, 2011;13:64. et al, for the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) 21. Michel JB, Virmani R, Arbustini E, Pasterkamp G. Intraplaque haemor- Study Group. Asymptomatic internal and rhages as the trigger of plaque vulnerability. Eur Heart J 2011;32:1977-85. cerebrovascular risk stratification. J Vasc Surg 2010;52:1486-96. 22. Chu B, Kampschulte A, Ferguson MS, Kerwin WS, Yarnykh VL, 34. Arai D, Yamaguchi S, Murakami M, Nakakuki T, Fukuda S, Satoh- O’Brien KD, et al. Hemorrhage in the atherosclerotic carotid plaque: Asahara N, et al. Characteristics of carotid plaque findings on a high-resolution MRI study. Stroke 2004;35:1079-84. ultrasonography and black blood magnetic resonance imaging in 23. Moody AR, Murphy RE, Morgan PS, Martel AL, Delay GS, Allder S, comparison with pathological findings. Acta Neurochir Suppl et al. Characterization of complicated carotid plaque with magnetic 2011;112:15-9. resonance direct thrombus imaging in patients with cerebral ischemia. Circulation 2003;107:3047-52. 24. Singh N, Moody AR, Gladstone DJ, Leung G, Ravikumar R, Zhan J, et al. Moderate carotid artery stenosis: MR imaging-depicted intra- Submitted Aug 24, 2012; accepted Oct 14, 2012. plaque hemorrhage predicts risk of cerebrovascular ischemic events in asymptomatic men. Radiology 2009;252:502-8. 25. Altaf N, Daniels L, Morgan PS, Auer D, MacSweeney ST, Moody AR, Additional material for this article may be found online et al. Detection of intraplaque hemorrhage by magnetic resonance at www.jvascsurg.org. JOURNAL OF VASCULAR SURGERY 1051.e1 Millon et al April 2013

APPENDIX (online only). Criteria for identification of on precontrast mask of gadolinium-enhanced magnetic features of vulnerable carotid plaque resonance angiogram. Gadolinium enhancement in plaque: Both observers Lipid core. Isosignal on time of flight (TOF)- and visually analyzed signal changes in the vessel wall in the T1-weighted images and hyposignal to isosignal on proton postcontrast images as compared with corresponding pre- density (PD)-weighted images. contrast images and contoured the region of interest Large lipid core. Measurement was performed on the (ROI) where they found uptake. Using an in-house soft- image showing the thicker lipid-rich necrotic core ware for manual image registration, the mean signal inten- (LRNC) by dividing the thickness of the LRNC in the sity (SI) for each ROI was measured and normalized to the radial direction by the thickness of the plaque on the slice. SI in the adjacent sternocleidomastoid muscle. The A large LRNC was defined as one occupying more than percentage of SI change was automatically calculated as 50% of vessel wall thickness. follows: (SI plaque post 3 SI muscle pre)/(SI plaque pre Fibrous cap rupture. Disrupted dark band or no visible 3 SI muscle post). Precautions were taken to exclude dark band adjacent to the lumen on TOF-weighted angio- images with prominent flow artifacts. When pre- and post- grams and/or presence of fibrous cap discontinuity on contrast images could not be co-registered, data were postcontrast T1-weighted images. excluded from the analysis. Intraplaque hemorrhage. Hyperintense signal on TOF- and T1-weighted images and/or hyperintense signal

Supplementary Table (online only). Patient characteristics and plaque features: Evolution during the studya

Period 1b (n ¼ 52) Period 2b (n ¼ 51) Period 3b (n ¼ 51) P

Clinical characteristics: Symptoms 20 (38) 14 (27) 18 (35) .478 Demographics Age 70 (10, 43-86) 71 (10, 35-91) 69 (10, 45-91) .397/.368/.122 Female 17 (33) 13 (25) 14 (27) .704 Active smokers 13 (25) 11 (22) 13 (25) .880 Hypertension 38 (73) 41 (80) 39 (76) .680 Diabetes 13 (25) 18 (35) 17 (33) .487 Dyslipidemia 30 (58) 29 (57) 32 (63) .807 Body mass index 26 (4, 19-34) 26 (4, 19-36) 27 (4, 22-34) .926/.215/.249 Coronary artery disease 15 (29) 12 (23) 16 (31) .666 Medications Statin 40 40 42 .783 Aspirin 42 42 48 .108 Anticoagulant 7 5 2 Biological inflammatory markers Ultrasensitive C-reactive protein (mg/L) 7.7 (26.5, 0.4-37.5) 10.7 (25.9, 0.2-287) 5.1 (26.3, 0.6-30.5). .696/.237/.174 Fibrinogen (g/L) 4.0 (1.0, 2.4-6.8) 3.9 (1.0, 2.0-9.0) 3.9 (1.0, 2.6-6.5) .474/.523/1 Carotid plaque features Plaque thickness 4.7 (1.3, 3.0-8.1) 4.5 (1.3, 3.0-7.3) 4.9 (1.3, 3.0-8.3) .664/.533/.174 Degree of stenosis 63.2 66.9 73.1 .240/.007/.127 Intraplaque hemorrhage 9 11 16 .222 Fibrous cap rupture 9 10 5 .360 Gadolinium enhancement 31 34 30 .668 Large lipid core 18 15 11 .337 aContinuous variables were expressed as mean and standard deviation and range. Categorical variables were expressed as frequence and percentages. bPeriod 1: January to June 2010; period 2: June 2010 to March 2011; period 3: March to November 2011. JOURNAL OF VASCULAR SURGERY Volume 57, Number 4 Millon et al 1051.e2

Supplementary Fig (online only). Features of vulnerable carotid plaque: Magnetic resonance imaging and histological correlation. Fibrous cap rupture: Time of flight (TOF)-, proton density (PD)-, and T1-weighted sequences showed a fibrous cap discontinuity confirmed by a localized fibrous cap rupture on histolgy (hematoxylin and eosin [HE] staining). Intraplaque hemorrhage: Magnetic resonance angiography (MRA), mask, and PD- and T1-weighted sequences showed intraplaque hypersignal resulting from intraplaque hemorrhage confirmed by histology (HE staining). Gadolinium enhancement: T1-weighted and post-gadolinium T1-weighted sequences showed focal enhancement in the shoulder region of the plaque corresponding to an area rich in neovessels (CD34þ) and macrophages (CD68þ). Lipid core: PD-, T1-, and post-gadolinium T1-weighted sequences showed intraplaque isosignal (PD- and T1-weighted sequences) and hyposignal (post- gadolinium T1-weighted sequence) corresponding to a large lipid core on histology (HE stain).