Confidence interval for relative difference under inverse sampling

The objective of this study was to compare two portable lactate analyzers for testing canine patients in a clinical setting with a previously accepted methodology for measuring plasma lactate. Between Jan 1, 2005 and Jun 1, 2006, all samples were analyzed using two different portable analyzers (devices A and B), and 86 of those samples were also analyzed by a reference laboratory (REF). The concordance correlation coefficient (CCC) for device A and the REF was 0.949 (95% confidence interval [95% CI], 0.923–0.966). For device B and REF, the CCC was 0.990 (95% CI, 0.985–0.993). Only 8 of 85 samples (9.4%) exceeded a relative difference of 20% for device B (note that 1 of the 86 samples was not included because the lactate level fell below the detectable limit of device B), but 48 of 85 samples (56.5%) exceeded a relative difference of 20% for device A. Both portable lactate analyzers appeared to be effective in detecting clinically significant elevations in plasma lactate compared with the REF but device B had better agreement. A positive correlation among all three analyzers existed; however, the analyzers do not yield directly interchangeable results.

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Tests of Homogeneity for the Relative Difference between Strata under Inverse Sampling

Biometrical Journal ◽

10.1002/(sici)1521-4036(199806)40:2<227::aid-bimj227>3.0.co;2-r ◽

1998 ◽

Vol 40 (2) ◽

pp. 227-235 ◽

Cited By ~ 10

Author(s):

Kung-Jong Lui

Keyword(s):

Relative Difference ◽

Inverse Sampling

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SUV variability in EARL-accredited conventional and digital PET

EJNMMI Research ◽

10.1186/s13550-019-0569-7 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Daniëlle Koopman ◽

Pieter L. Jager ◽

Cornelis H. Slump ◽

Siert Knollema ◽

Jorn A. van Dalen

Keyword(s):

Confidence Interval ◽

Prospective Study ◽

Relative Difference ◽

Whole Body ◽

Pet Scanning ◽

Pet Ct ◽

Digital Pet ◽

Average Size ◽

Pet Scanners ◽

Pet Scans

Abstract Background A high SUV-reproducibility is crucial when different PET scanners are in use. We evaluated the SUV variability in whole-body FDG-PET scans of patients with suspected or proven cancer using an EARL-accredited conventional and digital PET scanner. In a head-to-head comparison we studied images of 50 patients acquired on a conventional scanner (cPET, Ingenuity TF PET/CT, Philips) and compared them with images acquired on a digital scanner (dPET, Vereos PET/CT, Philips). The PET scanning order was randomised and EARL-compatible reconstructions were applied. We measured SUVmean, SUVpeak, SUVmax and lesion diameter in up to 5 FDG-positive lesions per patient. The relative difference ΔSUV between cPET and dPET was calculated for each SUV-parameter. Furthermore, we calculated repeatability coefficients, reflecting the 95% confidence interval of ΔSUV. Results We included 128 lesions with an average size of 19 ± 14 mm. Average ΔSUVs were 6-8% with dPET values being higher for all three SUV-parameters (p < 0.001). ΔSUVmax was significantly higher than ΔSUVmean (8% vs. 6%, p = 0.002) and than ΔSUVpeak (8% vs. 7%, p = 0.03). Repeatability coefficients across individual lesions were 27% (ΔSUVmean and ΔSUVpeak) and 33% (ΔSUVmax) (p < 0.001). Conclusions With EARL-accredited conventional and digital PET, we found a limited SUV variability with average differences up to 8%. Furthermore, only a limited number of lesions showed a SUV difference of more than 30%. These findings indicate that EARL standardisation works. Trial registration This prospective study was registered on the 31th of October 2017 at ClinicalTrials.cov. URL: https://clinicaltrials.gov/ct2/show/NCT03457506?id=03457506&rank=1.

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