Journal of nuclear medicine : official publication, Society of Nuclear Medicine
-
Brown adipose tissue (BAT) has become a focus of research in the hope of finding a new target to fight obesity. Metabolic BAT activity can be visualized with (18)F-FDG PET/CT. Furthermore, the sympathetic innervation of BAT can be visualized with the radiolabeled norepinephrine analog (123)I-metaiodobenzylguanidine ((123)I-MIBG). We aimed to determine whether (123)I-MIBG SPECT/CT and (18)F-FDG PET/CT identify the same anatomic regions as active BAT in adult humans. Furthermore, we investigated whether the magnitude of BAT activity measured by these techniques correlated. Finally, we tried to establish the optimal time interval between (123)I-MIBG administration and subsequent SPECT/CT acquisition to visualize sympathetic stimulation of BAT. ⋯ (123)I-MIBG SPECT/CT, as a marker of sympathetic activity, and (18)F-FDG PET/CT, as a marker of metabolic activity, identified the same anatomic regions as active BAT. Moreover, when (123)I-MIBG SPECT/CT was performed at 24 h after (123)I-MIBG administration, the magnitude of BAT activity measured with these techniques correlated strongly. This finding not only supports that BAT activity in humans is sympathetically influenced but also identifies (123)I-MIBG SPECT/CT, when performed 24 h after (123)I-MIBG injection, as a method to visualize and quantify sympathetic stimulation of BAT.
-
Neuroblastic tumors are childhood neoplasms that possess amino acid decarboxylase (AADC) activity and can theoretically be imaged by (18)F-fluorodihydroxyphenylalanine ((18)F-FDOPA) PET, a new diagnostic tool for neuroendocrine tumors. In this study, we explored the accuracy and clinical role of (18)F-FDOPA PET in neuroblastic tumors. ⋯ (18)F-FDOPA PET showed high sensitivity and specificity in detecting and tracking neuroblastic tumors in this preliminary study with a small cohort of patients and might be complementary to (123)I-MIBG scintigraphy and (18)F-FDG PET. By correlating with AADC expression, (18)F-FDOPA PET might serve as a useful imaging tool for the functional assessment of neuroblastic tumors.
-
Two mitogen-activated protein kinase kinase (MAPK2, also known as MEK) inhibitors were assessed with (18)F-FDG PET in separate phase I clinical studies, clearly illustrating the potential of metabolic imaging for dose, dosing regimen, and compound selection in early-phase trials and utility for predicting nonresponding patients. ⋯ These data exemplify the role of (18)F-FDG PET for guiding the selection of novel investigational drugs, choosing dose in early-phase clinical development, and predicting nonresponding patients early in treatment.
-
(18)F-FDG PET/CT allows the direct measurement of metabolic tumor burden in a variety of different malignancies. The aim of this study was to assess whether metabolic tumor volume (MTV) determined by (18)F-FDG PET/CT could be used in the prediction of progression-free and overall survival in multiple myeloma patients. ⋯ The direct measurement of tumor burden obtained by calculating MTV on (18)F-FDG PET/CT images may be used in the prediction of progression-free and overall survival in myeloma patients.
-
Comparative Study
Comparison of segmentation-based attenuation correction methods for PET/MRI: evaluation of bone and liver standardized uptake value with oncologic PET/CT data.
For attenuation correction (AC) in PET/MRI systems, segmentation-based methods are most often used. However, the standardized uptake value (SUV) of lesions in the bone and liver, which have higher attenuation coefficients than other organs, can be underestimated, potentially leading to misinterpretation of clinical cases. Errors in SUV estimation are also dependent on the segmentation schemes used in the segmentation-based AC. In this study, this potential bias in SUV estimation using 4 different segmentation-based AC methods was evaluated for the PET/CT data of cancer patients with bone and liver lesions. ⋯ Without bone segmentation, the SUVs of spine lesions were considerably underestimated; however, the bias was acceptable with bone segmentation. In liver lesions, the segmentation-based AC methods yielded a negative bias in SUV; however, inclusion of the bone and fat segments reduced the SUV bias. The results of this study will be useful for understanding organ-dependent bias in SUV between PET/CT and PET/MRI.