Standardized uptake rate (SUV)

Standardized uptake value, SUV, (also referred to as the dose uptake ratio, DUR) is a widely used, simple PET quantifier, calculated as a ratio of tissue radioactivity concentration (e.g. in units kBq/ml) at time T, CPET(T) and injected dose (e.g. in units MBq) at the time of injection divided by body weight (e.g. in units kg).

SUVbw = CPET(T) / (Injected dose / Patient's weight)

Instead of body weight, the injected dose may also be corrected by the lean body mass, or body surface area (BSA) (Kim et al., 1994). Verbraecken et al. (2006) review the different formulas for calculating the BSA.

SUVbsa= CPET(T) / (Injected dose / BSA)

If the above mentioned units are used, the unit of SUV will be g/ml.

Cancer treatment responce is usually assessed with FDG PET by calculating the SUV on the highest image pixel in the tumour regions (SUVmax). Alternatively, tumour volume can be estimated using threshold or region growing techniques, and average SUV inside the region is reported as such or multiplied by tumour volume to calculate the total glycolytic volume, TGV (Boucek et al., 2008). Nahmias and Wahl (2008) reported that the use of SUVmax has worse reproducibility (3% ± 11%) than does the SUVmean value (1% ± 7%).

Calculation of SUV does not require blood sampling or dynamic imaging. The imaging must take place at a late time point, and always at the same time point, if results are to be compared (Eckelman et al., 2000).

SUV drawbacks

SUV is vulnerable to several major sources of variability (Hamberg et al. 1994; Keyes 1995; Huang 2000), and the application of SUV as a quantitative index should be discouraged. The only reason for its continuous usage is that blood sampling is not necessary. If blood samples have been measured, a simple but quantitative alternative to SUV is fractional uptake rate (FUR), which is an approximation to the Gjedde-Patlak slope Ki. FUR and SUV are proportional, related by plasma clearance rate and a dimensionless initial distribution volume (Thie, 1995). Although SUV and Ki may correlate well over the patient population, they may provide even opposite conclusios regarding the progression of disease (Freedman et al., 2003). Image noise, poor resolution and ROI definition affect the SUV and may hamper their use, especially in multicenter trials (Boellaard et al., 2004).

See also:



References:

Boellaard R, Krak NC, Hoekstra OS, Lammertsma AA. Effects of noise, image resolution, and ROI definition on the accuracy of standard uptake values: a simulation study. J Nucl Med 2004; 45: 1519-1527.

Boucek JA, Francis RJ, Jones CG, Khan N, Turlach BA, Green AJ. Assessment of tumour response with 18F-fluorodeoxyglucose positron emission tomography using three-dimensional measures compared to SUVmax - a phantom study. Phys Med Biol. 2008; 53(16): 4213-4230.

Eckelman WC, Tatum JL, Kurdziel KA, Croft BY. Quantitative analysis of tumor biochemistry using PET and SPECT. Nucl Med Biol 2000; 27: 633-635.

Freedman NMT, Sundaram SK, Kurdziel K, Carrasquillo JA, et al. Comparison of SUV and Patlak slope for monitoring of cancer therapy using serial PET scans. Eur J Nucl Med 2003; 30: 46-53.

Hamberg LM, Hunter GJ, Alpert NM, Choi NC, Babich JW, Fischman AJ. The dose uptake ratio as an index of glucose metabolism: useful parameter or oversimplification. J Nucl Med. 1994; 35: 1308-1312.

Huang S-C. Anatomy of SUV. Nucl Med Biol 2000; 27: 643-646.

Keyes JW Jr. SUV: Standard uptake or silly useless value? J Nucl Med 1995; 36: 1836-1839.

Kim CK, Gupta NC, Chandramouli B, Alavi A. Standardized uptake values of FDG: body surface area correction is preferable to body weight correction. J Nucl Med. 1994; 35: 164-167.

Nahmias C, Wahl LM. Reproducibility of standardized uptake value measurements determined by 18F-FDG PET in malignant tumors. J Nucl Med. 2008; 49 (11): 1804-1808.

Thie JA. Clarification of a fractional uptake concept. J Nucl Med 1995; 36:711-712.

Thie JA. Understanding the standardized uptake value, its methods, and implications for usage. J Nucl Med 2004; 45: 1431-1434.

Thie JA, Hubner KF, Isidoro FP, Smith GT. A weight index for the standardized uptake value in 2-Deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography. Mol Imaging Biol. 2007; 9(2): 91-98.

Verbraecken J, Van de Heyning P, De Backer W, Van Gaal L. Body surface area in normal-weight, overweight, and obese adults. A comparison study. Metab Clin Exp 2006; 55: 515-524.



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