Image Viewer > Advanced Viewing > Standardized Uptake Value (SUV)

This is a premium feature and may not be available in all installations.

Standardized uptake value (SUV) is a tool commonly used in PET image analysis. It measures the concentration of a radiotracer in a defined region of interest (ROI). The value is calculated based on the information stored in the DICOM image.

Important Note

SUV calculation in ClearCanvas Workstation is based on generally accepted methods and equations. However, some institutions may use methods and/or equations that differ from those stated in this user's guide. Prior to use in a clinical setting, it is important that all equations be confirmed and an independent evaluation be conducted of the SUV values reported by ClearCanvas Workstation with studies from all the PET acquisition devices at your facility, under typical acquisition conditions. See the Safety Instructions for more details.

SUV Region Measurements

SUV is calculated for 2D ROI measurements (elliptical, rectangular and polygonal ROIs) when they are drawn on a PET or PET-CT fusion image. The following information is displayed in the callout:

•	The SUV calculation method: body weight (bw), lean body mass (lbm) or body surface area (bsa); this can be changed in the configuration

•	The SUV units used

•	The mean and maximum SUV in the region

Notes

•	SUV is calculated entirely based on the information stored in the image header. It is the technician's responsibility to ensure all necessary information is entered correctly. See this for the list of tags that are required.

•	The images must be decay-corrected.

•	If SUV cannot be computed due to missing or invalid data, check the log for the exact problem.

•	Many factors can affect the accuracy of SUV measurements, including image noise/background activity, attenuation correction and patient motion artifacts, partial volume effects, patient size, the timing of the scan post-injection, as well as user-bias when drawing the ROI.

SUV on PET/CT Fusion Images

Since PET/CT fusion images are constructed from a volume generated from the PET images, SUV computation is subject to the interpolation algorithm used in the software. In addition, information used for computing SUV must be consistent across all PET images. As such, it is possible that SUV can be computed on a single PET image but not on the fusion image. It is also common that SUV reported on fusion images are slightly different from those on the PET images. If there is ever any doubt about the SUV value reported on a fusion image, you can always draw the same ROI on the closest image in the source PET series.

Calculation Details

SUV Formulas

Parameter	Description	Unit
C(t)	Activity Concentration	Bq/ml
DI	Injected Dose	Bq
d	Dose Decay Correction Factor
W	Body Weight	g
LBM	Lean Body Mass	g
BSA	Body Surface Area	cm2

Required Data

The following DICOM tags are used to calculate SUV via the various methods:

Tag	Description	Expected Value	Used For
(0010,0040)	Patient's Sex	M or F	SUVlbm
(0010,1020)	Patient's Size	Patient's height in metres	SUVlbm , SUVbsa
(0010,1030)	Patient's Weight	Patient's weight in kg	SUVbw , SUVlbm , SUVbsa
(0008,0021)	Series Date		Decay correction
(0008,0031)	Series Time		Decay correction
(0018,1078)	Radiopharmaceutical Start DateTime	Radiopharmaceutical administration time	Decay correction
(0018,1072)	Radiopharmaceutical Start Time	Radiopharmaceutical administration time	Decay correction
(0018,1074)	Radionuclide Total Dose	Radiopharmaceutical dose administered to patient at administration time in becquerels (Bq)	Injected Dose
(0018,1075)	Radionuclide Half Life	Radionuclide half life in seconds	Decay correction
(0054,1001)	Units	Pixel value units (after conversion)
(0028,1053), (0028,1052)	Rescale Slope, Rescale Intercept	Non-zero slope	Converts pixel values to Bq/ml (Activity Concentration)

Additionally, the following manufacturer-specific tags are used in the calculation.

Manufacturer	Tag	Description	Expected Value	Used For
Philips	(7053,xx00)	Philips' private tag for SUV Scale Factor	Non-zero	Only used for Philips images to calculate SUV directly from pixel values
Philips	(7053,xx09)	Philips' private tag for Activity Concentration Scale Factor	Non-zero	Only used for Philips images to convert pixel values to Bq/ml (Activity Concentration)
GE	(0009,xx0D)	GE's private tag for scan time		Decay correction (for post-processed series only)

Lean Body Mass

Lean body mass is calculated using the James formula for females and the Morgan formula for males:

Male		[1]
Female		[2]

W = Patient's Weight in kg H = Patient's Height in cm

Body Surface Area

Body surface area is calculated using the Du Bois formula:

[3]

W = Patient's Weight in kg H = Patient's Height in cm

Decay Correction

The injected dose used to calculate SUV is corrected for the decay that occurs between the time of injection and the start of the scan using the formula:

T1/2 = Radionuclide half life in seconds

If Decay Correction = START, = Series Time - Radiopharmaceutical Start Time (for GE post-processed series, series time is retrieved from the private tag)

If Decay Correction = ADMIN, = 0

Note

ClearCanvas Workstation will not calculate SUV on images that have not been decay-corrected by the acquisition device.

References

[1]	James, W. Philip T. Research on obesity. London: Her Majesty's Stationery Office, 1976. ISBN 0114500347.

[2]	Morgan, Denis J. and Bray, Kelly M. Lean Body Mass as a Predictor of Drug Dosage: Implications for Drug Therapy. Clinical Pharmacokinetics. 1994, Vol. 26, 4, pp. 292-307.

[3]	Du Bois, Delafield and Du Bois, Eugene F. A formula to estimate the approximate surface area if height and weight be known. Archives of Internal Medicine. 1916, Vol. 17, 6-2, pp. 863-871.