Mismatch volume

Glycolysis tends to increase in situations of limited perfusion, for example in hibernating myocardium after infarction, and in hypoxic tumours. This perfusion-metabolism mismatch has been evaluated with combination of two PET studies, one for measuring perfusion using for example [15O]H2O, and another for measuring glucose uptake using [18F]FDG.

Komar et al (2009) have shown that in malignant pancreatic tumours blood flow is decreased and glucose metabolism increased, compared to healthy pancreatic tissue. The ratio of glucose uptake to perfusion was better predictor of poor survival than high glucose uptake and low perfusion separately.

Calculation of absolute mismatch volume (aMMV) and relative mismatch volume (rMMV) have been proposed as a method for quantification of the spatial extent of perfusion metabolism mismatch (Apostolova et al., 2014).

Calculation of aMMV and rMMV

Apostolova et al. (2014) delineated metabolically active tumour in FDG image, and then classified each pixel inside the tumour: if FDG uptake (SUV) was higher than the median tumour FDG uptake, and perfusion was smaller than the median perfusion, the the voxel was classified as mismatched. Absolute mismatch volume was defined as the volume of all mismatched voxels in millilitres, and the relative mismatch volume as the ratio of aMMV to the metabolically active tumour volume (MTV).

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Apostolova I, Hofheinz F, Buchert R, Steffen IG, Michel R, Rosner C, Prasad V, Köhler C, Derlin T, Brenner W, Marnitz S. Combined measurement of tumor perfusion and glucose metabolism for improved tumor characterization in advanced cervical carcinoma. A PET/CT pilot study using [15O]water and [18F]fluorodeoxyglucose. Strahlenther Onkol. 2014; 190: 575-581.

Komar G, Kauhanen S, Liukko K, Seppänen M, Kajander S, Ovaska J, Nuutila P, Minn H. Decreased blood flow with increased metabolic activity: a novel sign of pancreatic tumor aggressiveness. Clin Cancer Res. 2009; 15(17): 5511–5517.

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Created at: 2014-10-31
Updated at: 2015-07-08
Written by: Vesa Oikonen