A weight index for the standardized uptake value in 2-Deoxy-2-[F-18]fluoro-d-glucose-positron emission tomography

Joseph A. Thie, Karl Hubner, Francis P. Isidoro, Gary T. Smith

Research output: Contribution to journalArticle

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Abstract

Introduction: Known errors in the standardized uptake value (SUV) caused by variations in subject weights W encountered can be corrected by lean body mass or body surface area (bsa) algorithms replacing W in calculations. However this is infrequently done. The aims of the work here are: quantify sensitivity to W, encourage SUV correction with an approach minimally differing from tradition, and show what improvements in the SUV coefficient of variation (cv) for a population can be expected. Methods: Selected for analyses were 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) SUV data from positron emission tomography (PET) and PET/computed tomography (CT) scans at the University of Tennessee as well as from the literature. A weight sensitivity index was defined as -n=slope of ln (SUV/W) vs. lnW. The portion of the SUV variability due to this trend is removed by using the defined SUVn = Q × Wn × Wavg1-n/ID, or a virtually equal SUV m using w = n: SUVm = Q × (wW + (1-w)Wavg)/ID, with Q and ID being tissue specific-activity and injected dose. F = (cv of SUVn or of SUV m)/ (cv of traditional SUV) measures performance. Adapting to animal studies' tradition, %WmID/wt = 100 × SUVm is preferred over the conventional %ID/wt = 100 × Q/ID. Results: For FDG in adults n = w = 0.44 ± 0.03(s.e.) from averaging over most tissues. In children, however, n = w = 0.67 ± 0.05. Tissues have the same index if their influx constants are independent of W. Suggested, therefore, is a very simplified SUVm = Q × 1/2(W + Wavg)/ ID, which is dimensionless and keeps the same population averages as traditional SUVs. It achieves F = (1 - 0.011/(cv of SUV)2)1/2. Hence, for cv's of SUVs below ∼1/3 improvements over tradition are possible, leading to F's<0.95. Accounting additionally for height, as in SUVbsa, gives very little improvement over the simplified approach here and gives essentially the same F's as SUVm. Conclusions: Introduced here is a weight index useful in reducing variability and further understanding the SUV. Addressing weight sensitivity is appropriate where the cv of the SUVs is below about 1/3. Proposed is the very simple approach of using an average of an adult patient's weight and ∼70 kg for FDG SUV calculations. Unlike other approaches the dimensionless population average of SUVms is unchanged from tradition.

Original languageEnglish (US)
Pages (from-to)91-98
Number of pages8
JournalMolecular Imaging and Biology
Volume9
Issue number2
DOIs
StatePublished - Mar 1 2007

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Positron-Emission Tomography
Weights and Measures
Glucose
Population
Body Surface Area

All Science Journal Classification (ASJC) codes

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

Cite this

A weight index for the standardized uptake value in 2-Deoxy-2-[F-18]fluoro-d-glucose-positron emission tomography. / Thie, Joseph A.; Hubner, Karl; Isidoro, Francis P.; Smith, Gary T.

In: Molecular Imaging and Biology, Vol. 9, No. 2, 01.03.2007, p. 91-98.

Research output: Contribution to journalArticle

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abstract = "Introduction: Known errors in the standardized uptake value (SUV) caused by variations in subject weights W encountered can be corrected by lean body mass or body surface area (bsa) algorithms replacing W in calculations. However this is infrequently done. The aims of the work here are: quantify sensitivity to W, encourage SUV correction with an approach minimally differing from tradition, and show what improvements in the SUV coefficient of variation (cv) for a population can be expected. Methods: Selected for analyses were 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) SUV data from positron emission tomography (PET) and PET/computed tomography (CT) scans at the University of Tennessee as well as from the literature. A weight sensitivity index was defined as -n=slope of ln (SUV/W) vs. lnW. The portion of the SUV variability due to this trend is removed by using the defined SUVn = Q × Wn × Wavg1-n/ID, or a virtually equal SUV m using w = n: SUVm = Q × (wW + (1-w)Wavg)/ID, with Q and ID being tissue specific-activity and injected dose. F = (cv of SUVn or of SUV m)/ (cv of traditional SUV) measures performance. Adapting to animal studies' tradition, {\%}WmID/wt = 100 × SUVm is preferred over the conventional {\%}ID/wt = 100 × Q/ID. Results: For FDG in adults n = w = 0.44 ± 0.03(s.e.) from averaging over most tissues. In children, however, n = w = 0.67 ± 0.05. Tissues have the same index if their influx constants are independent of W. Suggested, therefore, is a very simplified SUVm = Q × 1/2(W + Wavg)/ ID, which is dimensionless and keeps the same population averages as traditional SUVs. It achieves F = (1 - 0.011/(cv of SUV)2)1/2. Hence, for cv's of SUVs below ∼1/3 improvements over tradition are possible, leading to F's<0.95. Accounting additionally for height, as in SUVbsa, gives very little improvement over the simplified approach here and gives essentially the same F's as SUVm. Conclusions: Introduced here is a weight index useful in reducing variability and further understanding the SUV. Addressing weight sensitivity is appropriate where the cv of the SUVs is below about 1/3. Proposed is the very simple approach of using an average of an adult patient's weight and ∼70 kg for FDG SUV calculations. Unlike other approaches the dimensionless population average of SUVms is unchanged from tradition.",
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N2 - Introduction: Known errors in the standardized uptake value (SUV) caused by variations in subject weights W encountered can be corrected by lean body mass or body surface area (bsa) algorithms replacing W in calculations. However this is infrequently done. The aims of the work here are: quantify sensitivity to W, encourage SUV correction with an approach minimally differing from tradition, and show what improvements in the SUV coefficient of variation (cv) for a population can be expected. Methods: Selected for analyses were 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) SUV data from positron emission tomography (PET) and PET/computed tomography (CT) scans at the University of Tennessee as well as from the literature. A weight sensitivity index was defined as -n=slope of ln (SUV/W) vs. lnW. The portion of the SUV variability due to this trend is removed by using the defined SUVn = Q × Wn × Wavg1-n/ID, or a virtually equal SUV m using w = n: SUVm = Q × (wW + (1-w)Wavg)/ID, with Q and ID being tissue specific-activity and injected dose. F = (cv of SUVn or of SUV m)/ (cv of traditional SUV) measures performance. Adapting to animal studies' tradition, %WmID/wt = 100 × SUVm is preferred over the conventional %ID/wt = 100 × Q/ID. Results: For FDG in adults n = w = 0.44 ± 0.03(s.e.) from averaging over most tissues. In children, however, n = w = 0.67 ± 0.05. Tissues have the same index if their influx constants are independent of W. Suggested, therefore, is a very simplified SUVm = Q × 1/2(W + Wavg)/ ID, which is dimensionless and keeps the same population averages as traditional SUVs. It achieves F = (1 - 0.011/(cv of SUV)2)1/2. Hence, for cv's of SUVs below ∼1/3 improvements over tradition are possible, leading to F's<0.95. Accounting additionally for height, as in SUVbsa, gives very little improvement over the simplified approach here and gives essentially the same F's as SUVm. Conclusions: Introduced here is a weight index useful in reducing variability and further understanding the SUV. Addressing weight sensitivity is appropriate where the cv of the SUVs is below about 1/3. Proposed is the very simple approach of using an average of an adult patient's weight and ∼70 kg for FDG SUV calculations. Unlike other approaches the dimensionless population average of SUVms is unchanged from tradition.

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