Volume 32, No.1, 2023
Original Article
Normal norms of carotid vessel wall volume in Taiwanese adults as measured using three-dimensional ultrasound

Chih-Chen  Liao,  1 , Pei-Ya  Chen,  2 , Shinn-Kuang  Lin,  3 , 
1 Stroke Center and Department of Neurology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taiwan
2 Stroke Center and Department of Neurology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan
3 Stroke Center and Department of Neurology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan
Corresponding Author:

Shinn-Kuang  Lin

keywords: carotid ultrasound, intima–media thickness, normal norms, three‐dimensional ultrasound, vessel wall volume

Purpose:The three-dimensional (3D) measurement of vessel wall volume (VWV) and plaque volume is sensitive for predicting cardiovascular risk. We established the normal norms of carotid VWV.

Methods: We retrospectively enrolled 352 patients with normal findings of the carotid ultrasound studies. Two-dimensional carotid intima-media thickness (IMT) was measured online. Grayscale 3D images of both sides of the carotid arteries were analyzed offline for measurement of IMT (QIMT) and VWV.
Results: The median age of the enrollees was 59 years. The median carotid IMT, QIMT, and VWV was 0.61 mm, 0.72 mm, and 90 mm3, respectively. No differences in IMT and VWV were observed between men and women or between the right and left side. We stratified participants into four groups, namely young adults (≤50 years), middle-aged adults (51–65 years), older adults (66–75 years), and senior adults (≥75 years). All the values of measured variables increased with advancing age. The median VWV of each group was 84, 90, 100, and 112 mm3, respectively. The increment percentage from young to senior adults was similar in terms of IMT and VWV. Nevertheless, the difference in the value of VWV (28 mm3) was much larger than that in IMT (0.18 mm). All three measured variables exhibited a positive linear correlation with age.
Conclusion: Both IMT and VWV have positive linear correlations with age. The application of QIMT measurements was limited by its inconsistent accuracy. VWV not only has a strong correlation with IMT but also enables observation of dynamic vessel wall changes, which is valuable for clinical
observational studies.
Keywords: carotid ultrasound, intima–media thickness, normal norms, three‐dimensional ultrasound,
vessel wall volume


The carotid arteries are one of the most easily screened arteries of the vascular system. Carotid atherosclerosis is associated with cardiovascular and cerebrovascular events(1,2), and the degree of carotid atherosclerosis has been used to estimate and classify individuals’ cardiovascular risk(3). The prevalence of increased carotid intima–media thickness (IMT) and carotid plaque is increasing in the general population worldwide(4). Carotid
IMT is the combined thickness of the intimal (20%) and medial (80%) layers of the carotid artery(5). Meta-analysis studies have demonstrated that carotid IMT only minimally improves predictive power beyond traditional risk factors(6). Carotid plaque is a more powerful predictor of cardiovascular risk than carotid IMT alone. However, focal thickening of the IMT typically coexists with protuberant plaque, and the two conditions are indistinguishable from each other. Therefore, measuring the thickness of the vessel wall, which comprises the intima–media and protuberant plaque, is more reasonable
than measuring the IMT or plaque alone(7). Carotid ultrasound is a noninvasive and reproducible study and is generally regarded as the standard imaging technique for primary evaluation of carotid atherosclerosis and plaque burden(5,8,9). With the continual advancements in ultrasound equipment and relevant software, the IMT, vessel wall, and plaque of the carotid artery can now be detected on a three-dimensional (3D) plane. Smaller
values of measured IMT can be converted to higher vessel wall volume (VWV) values, which enhances the feasibility of monitoring the sequential changes of carotid  plaque in a shorter duration and with fewer subjects  during clinical research(3,10). Furthermore, 3D assessment  of plaque volume is progressively more sensitive in  predicting cardiovascular risk than mere assessment of  plaque presence(6). We developed a standardized method  of 3D ultrasound measurement of carotid VWV with a  reasonable interobserver differences and high reliability(7).  In this study, we established the normal norms of carotid  VWV in Taiwanese adults and their association with age  and carotid IMT. 


A 3D transducer was available as part of the  ultrasound equipment in our institute, and rapid 3D carotid  ultrasound scanning of bilateral carotid arteries is included  in the regular carotid ultrasonography program. Through  a retrospective review, patients who were referred to the  sonographic laboratory from the outpatient clinic for  carotid duplex sonography and had normal findings of  bilateral carotid arteries on a B-mode scan with available  3D images were enrolled in this study. Ethical approval for this study was provided by the Institutional Review  Board of Taipei Tzu Chi Hospital, New Taipei City,  on August 7, 2020 (no. 09-X-063). Informed written  consent was waived because the study constituted a  retrospective data analysis. The detailed procedures of  the two-dimensional (2D) and 3D carotid ultrasound  were described in a previous report(7). In brief, we used an  Affiniti 70 ultrasound system (Philips Healthcare, Bothell,  WA, USA) to measure the 2D carotid IMT at a mean  distance of 1 cm from the far wall of the distal common  carotid artery (CCA) bilaterally with the built-in autotrace  function of the scanning equipment. Grayscale 3D images  of the carotid artery from the distal CCA to the internal  carotid artery on both sides were acquired using a single sweep VL15-3 transducer. The 3D images were analyzed  offline on a computer by using the vascular plaque  quantification function of the Philips QLAB software. The  standardized method of measuring the carotid VWV was  employed, with measurements taken from a 1-cm segment  of the distal CCA that was 1 cm proximal to the carotid  bifurcation (Figure 1A) with a preset IMT of 0.4 mm.  The intima–media area was defined as the area between  the outer and inner vessel walls. Plaque area was defined  as the area between the lumen boundary and inner vessel  wall, and the wall area was defined as the sum of the  intima–media area and plaque area (Figure 2B). Measured  data from all frames were exported as an Excel file.  From the exported Excel file, we manually computed the  mean intima–media thickness (QIMT) and VWV of the  measured 1-cm segment at the junction of the distal CCA  and CCA bifurcation. The 3D image measurements were  taken by a trained neurology resident. Continuous variables were computed as the median  (first to third quartile). The Mann–Whitney U and Kruskal–Wallis tests were used to evaluate differences in  continuous variables. P < 0.05 was considered statistically  significant. The correlation between the measured  variables and age was analyzed through linear regression.  All statistical analyses were performed using the MedCalc software package (version 18, Mariakerke, Belgium). 


A total of 352 patients were enrolled in this study,  including 147 men and 205 women. A total of 704 carotid  arteries (including right and left sides) were measured.  The median age was 59 (51–68) years, with no difference  noted between men and women. The median 2D carotid  IMT of the 704 carotid arteries in the 352 patients, which  was automatically traced using the ultrasound equipment,  was 0.61 (0.52–0.70) mm (Table 1). The median QIMT  and VWV, which were manually measured using QLAB  software, were 0.72 (0.63–0.85) mm and 90 (86–98)  mm3, respectively. No differences in IMT and VWV were  observed between men and women or between the right  and left side of the carotid arteries. A higher QIMT was  observed in women and on the right side than in men  and on the left side. The median value of the manually  measured QIMT (0.74 mm [0.63–0.85 mm]) was higher  than that of the automatically traced IMT (0.61 mm [0.52– 0.70 mm]; P < 0.0001; Figure 2).  

To identify the effect of age on the carotid vessel wall,  we classified the enrollees into four age groups, namely  young adults (≤50 years), middle-aged adults (51–65  years), older adults (66–75 years), and senior adults (age:  ≥75 years). The number of participants in the senior adults  group was only 23, which is possibly attributable to the  lower proportion of senior adults with normal carotid  



1. Baber U, Mehran R, Sartori S, Schoos MM, Sillesen H, Muntendam P, et al. Prevalence, impact, and predictive value of detecting subclinical coronary and carotid atherosclerosis in asymptomatic adults: the BioImage study. J. Am. Coll. Cardiol. 2015, 65, 1065-1074.

2. Kwon, H.; Kim, H.K.; Kwon, S.U.; Lee, S.W.; Kim, M.J.; Park, J.W.; et al. Risk of major adverse cardiovascular events in subjects with asymptomatic
mild carotid artery stenosis. Sci. Rep. 2018, 8, 4700, doi:10.1038/s41598-018-23125-8.
3. Johri AM, Nambi V, Naqvi TZ, Feinstein SB, Kim ESH, Park MM, et al. Recommendations for the assessment of carotid arterial plaque by ultrasound for the characterization of atherosclerosis and evaluation of cardiovascular risk: From the American Society of Echocardiography. J Am Soc Echocardiogr 2020; 33:917‐33.
4. Song, P.; Fang, Z.; Wang, H.; Cai, Y.; Rahimi, K.; Zhu, Y.; et al. Global and regional prevalence, burden, and risk factors for carotid atherosclerosis: a systematic review, meta-analysis, and modelling study. Lancet Glob Health. 2020, 8, e721-729, doi: 10.1016/S2214-109X(20)30117-0
5. Pignoli P, Tremoli E, Poli A, Oreste P, Paoletti R. Intimal plus medial thickness of the arterial wall: A direct measurement with ultrasound imaging. Circulation 1986;74:1399‐406.
6. Naqvi TZ, Lee MS. Carotid intima‐media thickness and plaque in cardiovascular risk assessment. JACC Cardiovasc Imaging 2014;7:1025‐38.
7. Chen YA, Chen PY, Lin SK. Three‐dimensional ultrasound for carotid vessel wall volume measurement. Tzu Chi Me J 2022;34(1):88-94.
8. Saba L, Anzidei M, Marincola BC, et al. Imaging of the carotid artery vulnerable plaque. Cardiovasc Intervent Radiol 2014;37:572–85.
9. Græbe M, Entrekin R, Collet-Billon A, Harrison G, Sillesen H. Reproducibility of two 3-D ultrasound carotid plaque quantification methods. Ultrasound
Med Biol 2014;40:1641-9.
10. Spence JD. Measurement of carotid plaque burden. JAMA Neurol 2015;72(4):383-4.
11. Stein JH, Korcarz CE, Hurst RT, Lonn E, Kendall CB, Mohler ER, et al. Use of carotid ultrasound to identify subclinical vascular disease and evaluate
cardiovascular disease risk: a consensus statement from the American Society of Echocardiography carotid intima-media thickness task force. Endorsed
by the Society for Vascular Medicine. J Am Soc Echocardiogr 2008;21:93-111.
12. O’Leary DH, Polak JF, Kronmal RA, Kittner SJ, Mond MG, Wolfson Jr SK, et al. Distribution and correlates of sonographically detected carotid artery
disease in the Cardiovascular Health Study. The CHS Collaborative Research Group. Stroke 1992;23:1752–60.
13. Spence JD, Hackam DG. Treating arteries instead of risk factors: a paradigm change in management of atherosclerosis. Stroke 2010;41:1193–9.
14. Moskau S, Golla A, Grothe C, Boes M, Pohl C, Klockgether T. Heritability of carotid artery atherosclerotic lesions: an ultrasound study in 154 families. Stroke 2005;36:5–8.
15. O’Leary DH, Polak JF, Kronmal RA, Manolio TA, Burke GL, Wolfson SK Jr. Carotid-artery intima and media thickness as a risk factor for myocardial
infarction and stroke in older adults. Cardiovascular Health Study Collaborative Research Group. N Engl JMed 1999;340:14 –22.
16. PiepoliMF, Hoes AW, Agewall S, Albus C, Brotons C, Catapano AL, et al. 2016 European Guidelines on cardiovascular disease prevention in clinical practice: The Sixth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of 10 societies and by invited experts) Developed with the special contribution of the European Association for Cardiovascular Prevention & Rehabilitation (EACPR). Eur Heart J 2016;37:2315-81.
17. Chen GC, Chen PY, Su YC, Hsiao CL, Yang FY, Hsu PJ, et al. Vascular, cognitive, and psychomental survey on elderly recycling volunteers in northern Taiwan. Front Neurol 2019;9:1176.
18. Sun Y, Lin CH, Lu CJ, Yip PK, Chen RC. Carotid atherosclerosis, intima-media thickness and risk factors: /an analysis of 1781 asymptomatic subjects in Taiwan. Atherosclerosis 2002;164:89-94.
19. Sandholt BV, Collet-Billon A, Entrekin R, Sillesen HH. Inter-scan reproducibility of carotid plaque volume measurements by 3-D ultrasound. Ultrasound Med Biol 2018;44:670-6.