The ratio of the activity concentration in a tissue to the injected activity spread over the body's mass. If the tracer were distributed evenly through the whole body, every tissue would read 1. It is dimensionless under the convention that tissue weighs 1 g per mL, and it depends on the uptake time, blood glucose, the reconstruction and how the region is drawn, which is why guidelines prescribe all of those before SUVs are compared.

Why decay-correct the injected activity?

The tissue concentration is measured at scan time; the injected activity is known at injection. The two must refer to the same moment, so the calculator decays the injected activity to the scan start. Many scanners instead decay-correct the image back to injection time; if your concentration is already expressed at injection time, or your dose is already corrected, tick the box and no correction is applied.

Why lean body mass or body surface area?

Fat takes up little FDG, so SUV by body weight rises with body weight in heavier patients. Normalizing to lean body mass (SUL, Sugawara 1999) or to body surface area (Kim 1994) reduces that dependence. PERCIST 1.0 adopted SUL with the Janmahasatian formula; the James formula is the older choice, and the two differ by a few percent, more at high BMI.

Is there a threshold?

None is shown here. Published cut-offs are specific to a tracer, a protocol, a scanner and a study population, and shift with uptake time, reconstruction and region definition; the EANM guideline lists the harmonization steps required before values from different sites are compared at all. Reading a scan is clinical work outside this page.

SUV calculator — body weight, lean mass, BSA

The standardized uptake value normalizes a PET tissue concentration to the injected activity and the patient's size, so that uptake can be compared between scans. This calculator computes SUV by body weight from the injected activity decay-corrected to scan time with the nuclide's half-life (¹⁸F by default) and, when height and sex are given, SUL with the James and the Janmahasatian lean-body-mass formulas and SUV by body surface area with the Du Bois formula. It is for imaging scientists, physicists and students learning how the number is built. It presents no thresholds.

Calculator

Tissue activity concentrationkBq/mL

The region's mean or maximum, as the scanner reports it.

Injected activityA

Net activity at injection time (syringe before, minus after).

RadionuclideT½ 109.77 min

Sets the half-life for the decay correction.

Injection to scanΔt

Time from injection to the scan start; the injected activity is decayed by it.

The injected activity is already decay-corrected to scan time

Body weightkg

kg.

Height (optional)cm

cm; with sex it adds lean body mass and surface area.

Sex (for lean body mass)

Not givenFemaleMale

Results

SUV by body weight: 3.553
Injected activity at scan time: 253.3MBq
Decay factor: 68.46%
SUL, Janmahasatian: 2.752
SUL, James: 2.794
Lean body mass, Janmahasatian: 58.08kg
Lean body mass, James: 58.99kg
SUV by body surface area · (kBq/mL)/(MBq/m²): 0.09016
Body surface area, Du Bois: 1.903m²
Body mass index: 24.49kg/m²

A drawing scale, not a threshold: the arc runs from 0 to 10 so the needle has room; values above 10 sit at the end.

For reference and education. Nothing on this page is clinical guidance, a dose recommendation or an Epitorix performance figure; check every number against your own validated procedures.

The formulas

EANM 2015 · PERCIST 1.0

Concentration over dose per size

SUV_bw: SUV_bw = C_tissue [kBq/mL] / (A_scan [MBq] / W [kg]) = C · W / A_scan; Tissue activity concentration over injected activity per body weight. With C in kBq/mL, A in MBq and W in kg the ratio is dimensionless (1 MBq/kg = 1 kBq/g, tissue taken as 1 g/mL).
A_scan: A_scan = A_inj · e^(−λ Δt), λ = ln 2 / T½; The injected activity decay-corrected to the scan start. ¹⁸F: T½ = 109.77 min, so 60 min leaves 68.47 %.
LBM, James: male 1.10 W − 128 (W/H)² ; female 1.07 W − 148 (W/H)²; Lean body mass in kg from weight (kg) and height (cm), James 1976, the formula Sugawara 1999 introduced to SUV.
LBM, Janmahasatian: male 9 270 W / (6 680 + 216 BMI) ; female 9 270 W / (8 780 + 244 BMI); Janmahasatian 2005, BMI = W / H² with H in m; the formula PERCIST 1.0 adopted for SUL.
SUL: SUL = C · LBM / A_scan; SUV normalized to lean body mass, with either formula.
SUV_bsa: BSA = 0.007 184 · W^0.425 · H^0.725 ; SUV_bsa = C · BSA / A_scan; Du Bois and Du Bois 1916, in m². SUV_bsa is on a different scale from SUV_bw, in (kBq/mL) per (MBq/m²).

Worked examples

¹⁸F T½ = 109.77 min

By hand

Each row is computed from the formulas above; the calculator reproduces every value.

Worked examples of SUV by body weight, lean body mass and body surface area.
Inputs	A_scan	SUV_bw	SUL James	SUL Janmahasatian	SUV_bsa
12 kBq/mL · 370 MBq ¹⁸F · 60 min · 75 kg, 175 cm, male	253.3 MBq	3.553	2.795 (LBM 58.99 kg)	2.752 (58.08 kg)	0.0902 (BSA 1.903 m²)
8.5 kBq/mL · 300 MBq ¹⁸F · 90 min · 62 kg, 165 cm, female	169.9 MBq	3.101	2.273 (45.44 kg)	2.005 (40.09 kg)	0.0841 (1.682 m²)
5 kBq/mL · 150 MBq ⁶⁸Ga · 45 min · 80 kg, 180 cm, male	94.63 MBq	4.227	3.314 (62.72 kg)	3.262 (61.73 kg)	0.1055 (1.996 m²)
12 kBq/mL · 370 MBq already corrected · 75 kg	370 MBq	2.432	—	—	—

Questions

What the numbers mean

What is an SUV?: The ratio of the activity concentration in a tissue to the injected activity spread over the body's mass. If the tracer were distributed evenly through the whole body, every tissue would read 1. It is dimensionless under the convention that tissue weighs 1 g per mL, and it depends on the uptake time, blood glucose, the reconstruction and how the region is drawn, which is why guidelines prescribe all of those before SUVs are compared.
Why decay-correct the injected activity?: The tissue concentration is measured at scan time; the injected activity is known at injection. The two must refer to the same moment, so the calculator decays the injected activity to the scan start. Many scanners instead decay-correct the image back to injection time; if your concentration is already expressed at injection time, or your dose is already corrected, tick the box and no correction is applied.
Why lean body mass or body surface area?: Fat takes up little FDG, so SUV by body weight rises with body weight in heavier patients. Normalizing to lean body mass (SUL, Sugawara 1999) or to body surface area (Kim 1994) reduces that dependence. PERCIST 1.0 adopted SUL with the Janmahasatian formula; the James formula is the older choice, and the two differ by a few percent, more at high BMI.
Is there a threshold?: None is shown here. Published cut-offs are specific to a tracer, a protocol, a scanner and a study population, and shift with uptake time, reconstruction and region definition; the EANM guideline lists the harmonization steps required before values from different sites are compared at all. Reading a scan is clinical work outside this page.

Sources

Boellaard R et al. FDG PET/CT: EANM procedure guidelines for tumour imaging, version 2.0. Eur J Nucl Med Mol Imaging 2015;42:328–354 (opens in a new tab) — SUV definitions, decay correction, harmonization
Sugawara Y et al. Reevaluation of the standardized uptake value for FDG: variations with body weight and methods for correction. Radiology 1999;213:521–525 (opens in a new tab) — SUL with the James 1976 lean-body-mass formula
Janmahasatian S et al. Quantification of lean bodyweight. Clin Pharmacokinet 2005;44:1051–1065 (opens in a new tab) — the lean-body-mass formula PERCIST uses
Wahl RL et al. From RECIST to PERCIST: evolving considerations for PET response criteria in solid tumors. J Nucl Med 2009;50 Suppl 1:122S–150S (opens in a new tab) — SUL in PERCIST 1.0
Kim CK et al. Standardized uptake values of FDG: body surface area correction is preferable to body weight correction. J Nucl Med 1994;35:164–167 (opens in a new tab) — SUV by body surface area
Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 1916;17:863–871 (reprinted Nutrition 1989;5:303–311) (opens in a new tab) — body surface area
Keyes JW. SUV: standard uptake or silly useless value? J Nucl Med 1995;36:1836–1839 (opens in a new tab) — what the number does and does not mean
ENSDF — Evaluated Nuclear Structure Data File, via NuDat 3 (opens in a new tab) — the half-lives used for decay correction

An educational tool. It evaluates the published SUV formulas from numbers you type; it does not read images, apply thresholds or support any clinical decision, and nothing here is an Epitorix performance figure.

Calculator

Results

Concentration over dose per size

By hand

What the numbers mean

The other six, open in the browser.