Skip to main content

Carotid atherosclerotic plaques standardized uptake values: methodological issues on reproducibility and accuracy

The Original Article was published on 07 September 2017


To assess accuracy and precision of the positron emission tomography-computed tomography (PET-CT) carotid standardized uptake values (SUV) of 18F–fluorodeoxyglucose (18FDG) as an inflammatory biomarker for determining cerebrovascular diseases such as stroke, methodology and statistical issues should be taken into account. Otherwise, misleading messages will be the main outcome of such research. Briefly, confusing accuracy and precision will mainly produce misleading messages.

I was interested to read the paper by Giannotti N and colleagues published in the Dec 2017 issue of EJNMMI Res [1]. Positron emission tomography-computed tomography (PET-CT) carotid standardized uptake values (SUV) of 18F–fluorodeoxyglucose (18FDG) have been proposed as an inflammatory biomarker for determining cerebrovascular diseases such as stroke. Consideration of varying methodological approaches and software packages is critical to the calculation of accurate SUVs in cross-sectional and longitudinal patient studies. They aimed to investigate whether or not carotid atherosclerotic plaque SUVs are consistent and reproducible between software packages [1]. 18FDG-PET SUVs of carotids were taken in 101 patients using two different software packages [1]. Data from five to seven anatomical sites were measured. A total of ten regions of interest (ROI) were drawn on each site. Based on their results statistically significant differences in SUV measurements, between the two software packages, ranging from 9 to 21.8% were found depending on ROI location. In 79% (n = 23) of the ROI locations, the differences between the SUV measurements from each software package were found to be statistically significant. They highlighted the importance of standardizing all aspects of methodological approaches to ensure accuracy and reproducibility.

However, reproducibility (precision, repeatability, reliability, or interchangeability) and accuracy (validity) are two completely different methodological issues [2,3,4,5,6,7,8]. The methodological approach and statistical estimates to assess these issues are completely different. For reliability purposes, our approach should be individual based. It means for continues variables, intraclass correlation coefficient (ICCC) absolute agreement single measure should be considered. 9 to 21% statistically significant differences in SUV measurements between the two software packages indicate that the authors did not applied this approach. They considered global average approach for reliability which is a common mistake and usually applied to assess accuracy of a test compared to a gold standard. It is crucial to know that a test can be accurate with no reliability and vice versa. Moreover, statistically significant should not be considered in reproducibility analysis because it dramatically depends on the sample size [2,3,4,5,6,7,8]. Finally, confusing precision and accuracy will mainly produce misleading messages.


  1. Giannotti N, O'Connell MJ, Foley SJ, Kelly PJ, McNulty JP. Carotid atherosclerotic plaques standardised uptake values: software challenges and reproducibility. EJNMMI Res. 2017;7(1):39. doi:10.1186/s13550-017-0285-0. Epub 2017 Apr 28

    Article  PubMed  PubMed Central  Google Scholar 

  2. Szklo M, Nieto FJ. Epidemiology beyond the basics. 2nd ed. Manhattan: Jones and Bartlett Publisher; 2007.

    Google Scholar 

  3. Sabour S. Reproducibility of 18F-fluoromisonidazole intratumour distribution in non-small cell lung cancer; methodological issues to avoid mismanagement of the patients. EJNMMI Res. 2017;7(1):23. doi:10.1186/s13550-017-0270-7. Epub 2017 Mar 16

    Article  PubMed  PubMed Central  Google Scholar 

  4. Sabour S. Reproducibility of semi-automatic coronary plaque quantification in coronary CT angiography with sub-mSv radiation dose; common mistakes. J Cardiovasc Comput Tomogr. 2016;10(5):e21–2. doi:10.1016/j.jcct.2016.07.002. Epub 2016 Jul 9

    Article  PubMed  Google Scholar 

  5. Sabour S, Ghassemi F. The validity and reliability of a signal impact assessment tool: statistical issue to avoid misinterpretation. Pharmacoepidemiol Drug Saf. 2016;25(10):1215–6. doi:10.1002/pds.4061.

    Article  PubMed  Google Scholar 

  6. Sabour S. Myocardial blood flow quantification by Rb-82 cardiac PET/CT: methodological issues on reproducibility study. J Nucl Cardiol. 2016;6 [Epub ahead of print]

  7. Sabour S, Ghassemi F. Accuracy and reproducibility of the ETDRS visual acuity chart: methodological issues. Graefes Arch Clin Exp Ophthalmol. 2016;254(10):2073–4. Epub 2016 Jul 5

    Article  PubMed  Google Scholar 

  8. Sabour S, Farzaneh F, Peymani P. Evaluation of the sensitivity and reliability of primary rainbow trout hepatocyte vitellogenin expression as a screening assay for estrogen mimics: methodological issues. Aquat Toxicol. 2015;164:175–6. doi:10.1016/j.aquatox.2015.05.003. Epub 2015 May 5

    CAS  Article  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Siamak Sabour.

Ethics declarations

Competing interests

The author declares that he/she has no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sabour, S. Carotid atherosclerotic plaques standardized uptake values: methodological issues on reproducibility and accuracy. EJNMMI Res 7, 62 (2017).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


  • 18F–FDG
  • Carotid atherosclerotic plaque
  • Positron emission tomography-computed tomography
  • Reproducibility
  • Accuracy