Figure 3 A & B.

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/X-ray computed tomography (CT) performed as a mid-therapy scan for the early assessment of treatment response. The PET/CT images are of a patient with a gastrointestinal stromal tumour. A: The image revealed intense ¹⁸F-FDG uptake in the primary tumour (arrow). A follow-up scan at the mid-therapy stage to assess treatment response revealed a mild reduction in the tumour size in the CT image (not included). B: The PET/CT image revealed a significant reduction in the ¹⁸F-FDG uptake, indicating a good response to treatment (arrow).