The appropriate whole body metric for calculating standardised uptake value and the influence of sex

Abstract

AimTo compare weight, lean body mass and body surface area for calculation of standardised uptake value (SUV) in fluorine-18-fluorodeoxyglucose PET/computed tomography, taking sex into account.Patients and methodsThis was a retrospective study of 161 (97 men) patients. Maximum standardised uptake value (SUVmax) and mean standardised uptake value (SUVmean) were obtained from a 3-cm region of interest over the right lobe of the liver and scaled to weight, scaled to lean body mass (SUL) and scaled to body surface area (SUA). Mean hepatic computed tomography density was used to adjust SUVmean for hepatic fat (SUVFA). Hepatic SUV indices were divided by SUV from left ventricular cavity, thereby, eliminating whole body metric, to obtain a surrogate of blood fluorine-18-fluorodeoxyglucose clearance into liver, and multiplied by blood glucose to give a surrogate of hepatic glucose uptake rate (mSUV).ResultsSULmax, SUAmax and all scaled to weight indices correlated strongly with weight. SULmean, SULFA, SUAmean and SUAFA, however, correlated weakly or not at all with weight, nor with their corresponding whole body metric in men or women, but correlated strongly when the sexes were combined into one group. This was the result of sex differences in SUL (greater in men) and SUA (greater in women). There was, however, no sex difference in mSUV.ConclusionWeight is unsuitable for calculating SUV. SUL and SUA are also inappropriate as maxima but appropriate as mean and fat-adjusted values. However, SUL is recommended for both sexes because SUA is influenced by both body fat and weight. Sex differences in SUL and SUA give rise to misleading correlations when sexes are combined into one group.

Utility of 68Ga‐DOTA‐Exendin‐4 positron emission tomography–computed tomography imaging in distinguishing between insulinoma and nesidioblastosis in patients with confirmed endogenous hyperinsulinaemic hypoglycaemia

“…The lack of complete information and difficulties with follow up in this series are some inherent limitations of a retrospective study. Because of minimal FDG uptake into adipose tissue SUVmax with weight correction overestimates real SUVmax by up to 70% in obese patients 29,30 . Ga‐68 Exendin shares this property, but, the resultant degree of overestimation is not available.…”

Rapid Standardized CT-Based Method to Determine Lean Body Mass SUV for PET—A Significant Improvement Over Prediction Equations

“…Janmahasatian’s equations were formulated on data from 303 healthy individuals with a mean age of 41 years, recruited from the students and staff of a university ( 17 ); James’ 56 subjects (mean age 60 years) were recruited from two specialist obesity clinics ( 18 ). Despite questionable applicability to cancer patients, most recent publications use either James’ or Janmahasatian’s equations to develop SUL values ( 15 , 19 ). The body habitus of contemporary cancer patients ranges from underweight to morbidly obese and includes wide variations in composition including highly skewed compositions such as sarcopenic obesity ( 7 , 20 , 21 ).…”

“…This being the case it is little wonder that some have taken to referring to the SUV as a "silly useless value" (14). Replacing TBM with LBM has been proposed to result in a more rigorous assessment of 18 F-FDG uptake (SUL) in reference and diseased tissues (13,15).…”

Hepatic and splenic 18F‐FDG blood clearance rates (Ki) in hepatic steatosis and diabetes mellitus

“…These studies, however, produced conflicting results with respect both to BGL (Busing et al , ; Groheux et al , ; Keramida et al , ; Eskian et al , ) and to hepatic steatosis (Abele & Fung, ; Bural et al , ; Kamimura et al , ; Abikhzer et al , ). Explanations for this inconsistency include firstly, variable use of maximum pixel SUV (SUV max ) and mean pixel SUV (SUV mean ) for quantification of FDG uptake; secondly, the physical diluting effect on the FDG signal of hepatic fat into which FDG does not penetrate (Keramida et al , ), and thirdly, the dependence of SUV on the whole body variable used to calculate it (Sugawara et al , ; Keramida & Peters, ). For example, with respect to the last‐mentioned, SUV that is calculated from body weight correlates with weight because FDG entry into adipose tissue is negligible, so SUV in any tissue in overweight people tends to be over‐estimated.…”