Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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For (18)F-FDG PET to be widely used to monitor atherosclerosis progression and therapeutic response, it is crucial to better understand how macrophage glucose metabolism is influenced by the atherosclerotic microenvironment and to elucidate the molecular mechanisms of this response. Oxidized low-density lipoprotein (oxLDL) is a key player in atherosclerotic inflammation that promotes macrophage recruitment, activation, and foam cell formation. We thus explored the effect of oxLDL on macrophage (18)F-FDG uptake and investigated the underlying molecular mechanism including the roles of hypoxia-inducible factor-1α (HIF-1α) and reactive oxygen species (ROS). ⋯ oxLDL is a strong stimulator of macrophage (18)F-FDG uptake and glycolysis through upregulation of GLUT1 and hexokinase. This metabolic response is mediated by Nox2-dependent ROS generation that promotes HIF-1α activation.
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There are different metabolic imaging methods, various tracers, and emerging anatomic modalities to stage neuroendocrine tumor (NET). We aimed to compare NET lesion detectability among (99m)Tc-hydrazinonicotinamide (HYNIC)-octreotide (somatostatin receptor scintigraphy [SSRS]) SPECT/CT, (68)Ga-DOTATATE PET/CT, and whole-body diffusion-weighted MR imaging (WB DWI). ⋯ (68)Ga PET/CT seems to be more sensitive for detection of well-differentiated NET lesions, especially for bone and unknown primary lesions. NET can be staged with (68)Ga-DOTATATE PET/CT. WB DWI is an efficient new method with high accuracy and without ionizing radiation exposure. SSRS SPECT/CT should be used only when (68)Ga-DOTATATE PET/CT and WB DWI are not available.
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α-(11)C-methyl-L-tryptophan (AMT) PET allows evaluation of brain serotonin synthesis and can also track upregulation of the immunosuppressive kynurenine pathway in tumor tissue. Increased AMT uptake is a hallmark of World Health Organization grade III-IV gliomas. Our recent study also suggested decreased frontal cortical AMT uptake in glioma patients contralateral to the tumor. The clinical significance of extratumoral tryptophan metabolism has not been established. In the present study, we investigated clinical correlates of tryptophan metabolic abnormalities in the nontumoral hemisphere of glioma patients. ⋯ These observations provide evidence for altered tryptophan uptake in contralateral cortical and thalamic brain regions in glioma patients after initial therapy, suggesting treatment effects on the serotonergic system. Low thalamic tryptophan uptake appears to be a strong, independent predictor of long survival in patients with previous glioma treatment.