Open Access

Response to letter re: Carotid atherosclerotic plaques standardized uptake values: methodological issues on reproducibility and accuracy

EJNMMI Research20177:73

https://doi.org/10.1186/s13550-017-0309-9

Received: 19 July 2017

Accepted: 19 July 2017

Published: 7 September 2017

The original article was published in EJNMMI Research 2017 7:62

Background

Dear Editor,

We would like to thank Dr. Siamak Sabour for his letter and comments relating to our recently published article [1]. In the manuscript, an investigation was conducted on whether or not carotid atherosclerotic plaque standardized uptake values (SUVs) are consistent and reproducible across software packages; therefore, the purpose of the analysis performed was to measure the reproducibility, rather than validity, of SUV measurements between two software packages (OsiriX MD® version 6.5.2, Pixmeo© SARL, Geneva, Switzerland and AquariusNet iNtuitionTM version 4.4.11, TeraRecon, Foster City, CA, USA) (Table 1).
Table 1

SUV measurements (mean and standard deviation) by location and software together with differences (mean and standard deviation)

Common carotid (CC) and internal carotid (IC) arteries

TeraRecon values (mean ± SD)

Osirix values (mean ± SD)

Difference in values (mean ± SD)

SUV mean bifurcation left

1.5 ± 0.36

1.58 ± 0.43

0.08 ± 0.003

SUV mean bifurcation right

1.56 ± 0.38

1.67 ± 0.46

0.11 ± 0.006

SUV mean CC left

1.08 ± 0.59

1.17 ± 0.6

0.09 ± 0.004

SUV mean CC right

1.11 ± 0.61

1.23 ± 0.64

0.12 ± 0.007

SUV mean IC left

1.56 ± 0.45

1.71 ± 0.57

0.15 ± 0.01

SUV mean IC right

1.66 ± 0.38

1.72 ± 0.44

0.06 ± 0.002

SUV max bifurcation left

2.54 ± 0.65

2.5 ± 0.7

0.04 ± 0.008

SUV max bifurcation right

2.6 ± 0.69

2.62 ± 0.73

0.02 ± 0.002

SUV max CC left

2.09 ± 0.91

2.06 ± 0.88

0.03 ± 0.001

SUV max CC right

2.14 ± 0.97

2.16 ± 0.99

0.02 ± 0.001

SUV max IC left

2.52 ± 0.67

2.57 ± 0.84

0.05 ± 0.001

SUV max IC right

2.6 ± 0.69

2.58 ± 0.74

0.02 ± 0.001

SUV min bifurcation left

0.71 ± 0.3

0.87 ± 0.36

0.16 ± 0.012

SUV min bifurcation right

0.76 ± 0.3

0.94 ± 0.38

0.18 ± 0.016

SUV min CC left

0.45 ± 0.36

0.56 ± 0.46

0.11 ± 0.006

SUV min CC right

0.48 ± 0.39

0.62 ± 0.48

0.14 ± 0.01

SUV min IC left

0.86 ± 0.34

1 ± 0.43

0.14 ± 0.01

SUV min IC right

0.84 ± 0.29

1 ± 0.34

0.16 ± 0.012

Conclusions

We acknowledge that the p values reported in the manuscript previously submitted are dependent on the study sample size, and may not provide sufficient support of measurement reliability. Thus, we will now provide the intra-class coefficient (ICC) for the relevant variables (see Tables 2, 3, and 4) which was found to be supportive of our initial findings.
Table 2

ICC for SUVs mean with 95% confidence intervals

Location

ICC

Confidence limit minimum

Confidence limit maximum

SUV mean bifurcation left

0.843

0.806

0.872

SUV mean bifurcation right

0.787

0.733

0.828

SUV mean CC left

0.906

0.887

0.922

SUV mean CC right

0.924

0.858

0.924

SUV mean IC left

0.79

0.713

0.842

SUV mean IC right

0.828

0.727

0.883

Table 3

ICC for SUVs max with 95% confidence intervals

Location

ICC

Confidence limit minimum

Confidence limit maximum

SUV max bifurcation left

0.826

0.803

0.846

SUV max bifurcation right

0.817

0.793

0.838

SUV max CC left

0.83

0.808

0.85

SUV max CC right

0.891

0.803

0.891

SUV max IC left

0.752

0.699

0.795

SUV max IC right

0.791

0.721

0.838

Table 4

ICC for SUVs min with 95% confidence intervals

Location

ICC

Confidence limit minimum

Confidence limit maximum

SUV min bifurcation left

0.627

0.494

0.773

SUV min bifurcation right

0.635

0.434

0.748

SUV min CC left

0.74

0.694

0.783

SUV min CC right

0.65

0.545

0.705

SUV min IC left

0.788

0.656

0.858

SUV min IC right

0.428

0.27

0.546

As expected, higher agreements (ICC) were found among SUV mean and maximum measurements. Effect size measurements also show that SUV max measurements were similar when compared (differences in mean values within the range: 0.02–0.05).

Once again we thank Dr. Sabour for his contribution to the important discussion around SUV measurements across software packages.

Notes

Declarations

Authors’ contributions

NG, JMN, SF and PK designed the study. MOC inputted into PET-CT acquisition and analysis. NG collected, anonymized and analysed all data sets. NG, SF and JMN worked together on statistical analysis and data interpretation. NG led the write up of the manuscript. JMN and PK oversaw the study. However, all authors contributed to revising the manuscript and all approved the final manuscript.

Competing interests

The authors declare that they have no competing interests.

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Authors’ Affiliations

(1)
Radiography and Diagnostic Imaging, School of Medicine, University College Dublin
(2)
Department of Radiology, Mater Misericordiae University Hospital
(3)
School of Medicine, University College Dublin
(4)
UCD Clinical Research Centre, School of Medicine, University College Dublin
(5)
Neurovascular Clinical Science Unit, Stroke Service and Department of Neurology, Mater University Hospital

Reference

  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.View ArticlePubMedPubMed CentralGoogle Scholar

Copyright

© The Author(s). 2017