Figure 4.

Imaging response to radiotherapy in a rat brain glioma model. A ¹³C chemical shift spectroscopic image obtained following the intravenous injection of hyperpolarised [1-¹³C]pyruvate is shown in (a), superimposed on a ¹H image of tissue anatomy. The chemical shift images were obtained from a 6-mm axial slice with an in-plane resolution of 2.53×2.53 mm². The tumour, which is readily observed in the contrast agent-enhanced image (b), was observed to increase in size following radiotherapy (lower image). However, the corresponding ¹³C images of pyruvate (c) and lactate (d), which were derived from spectroscopic images similar to those shown in (a), clearly show a relative decrease in lactate signal post therapy [compare signal intensities in the upper (before treatment) and lower images (after treatment)]. AU, arbitrary unit. Reproduced with permission from Day et al [39].