Metabolic volume

Glycolysis is increased in metabolically active tumours and in inflamed tissue, which can be detected using FDG PET imaging. FDG uptake is usually quantitated using semi-quantitative methods, most frequently SUV and especially SUVmax, despite its well-known limitations. In many recent studies, volume-based parameters such as metabolic tumour volume (MTV) and total lesion glycolysis (TLG) have been used (Hirata et al., 2014) and found to provide better prognostic indices than traditional SUV (Im et al., 2015; Vallius et al., 2018); comparison of the results is difficult since different methods are being used, and parameters are also heavily dependent on the PET scanner and reconstruction methods.

Metabolic volume is defined as the lesion volume within a delineated boundary. Several delineation methods have been used, including

Fixed and relative threshold based and lesion-to-background methods are easily applicable, but dependent on the image quality (resolution and noise) and lesion size. The more complex methods are more robust for the image quality, but dependent on the applied algorithm and software implementation (Schaefer et al., 2016; Gallamini & Kostakoglu, 2017).

Metabolic volume can naturally be used for analysis of other tracers as FDG (Hatt et al., 2010), and it can be based on for instance Ki images rather than SUV (Cheebsumon et al., 2011).

Metabolic activity

Metabolic volume can be multiplied with mean SUV of that volume to get metabolic activity (total lesion activity, lesion metabolic activity).

Cardiac metabolic activity (CMV) was used to analyze FDG studies in cardiac sarcoidosis (Ahmadian et al., 2014). SUV threshold should be determined based on the blood activity from heart cavity or aorta, instead of using fixed threshold or liver as reference region (Ahmadian et al., 2017 Furuya et al., 2018).


See also:



References:

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Hatt M, Cheze-Le Rest C, Aboagye EO, Kenny LM, Rosso L, Turkheimer FE, Albarghach NM, Metges J-P, Pradier O, Visvikis D. Reproducibility of 18F-FDG and 3’-deoxy-3’-18F-fluorothymidine PET tumor volume measurements. J Nucl Med. 2010; 51(9): 1368-1376.

Hirata K, Kobayashi K, Wong K-P, Manabe O, Surmak A, Tamaki N, Huang S-C. A semi-automated technique determining the liver standardized uptake value reference for tumor delineation in FDG PET-CT. PLoS ONE 2014; 9(8): e105682. doi: 10.1371/journal.pone.0105682.

Kruse V, Mees G, Maes A, D’Asseler Y, Borms M, Cocquyt V, Van De Wiele C. Reproducibility of FDG PET based metabolic tumor volume measurements and of their FDG distribution within. Q J Nucl Med Mol Imaging 2015; 59(4): 462-468.



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Created at: 2018-01-30
Updated at: 2018-10-09
Written by: Vesa Oikonen