- •
The recent development and introduction of new hybrid imaging devices combining positron emission tomography (PET) technology with magnetic resonance imaging (MRI) opens up new perspectives in clinical molecular imaging.
- •
Combining MRI and fluorine-18 choline PET would theoretically produce valuable clinical data in a single imaging session, which can be used for staging, prognosis, and assessment of treatment response.
- •
Fluorine-18–sodium fluoride (18F-NaF) is a highly sensitive PET tracer used as
PET/MRI Radiotracer Beyond 18F-FDG
Section snippets
Key points
Fluorine-18 choline/carbon-11 choline
Choline is an amino acid needed for the synthesis of phospholipids in cell membranes, methyl metabolism, cholinergic neurotransmission, transmembrane signaling, and lipid-cholesterol transport and metabolism. The most important metabolic process for the tumor detection is the aberrant phospholipid metabolism (upregulation of choline kinase), which results in an increased mitotic signaling and plasma membrane biosynthesis.1 Choline is transported inside the cell, phosphorylated, and metabolized
Gallium 68–tetraazacyclododecane tetraacetic acid–octreotate compounds
Gallium 68–tetraazacyclododecane tetraacetic acid–octreotate (68Ga-DOTATATE) is an amide of the acid 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), which binds a derivative of octreotide (Tyr)-octreotate.6 Similar molecules are [68Ga]-DOTA-D Phe1-Tyr3-Octreotide (68Ga-DOTATOC) (DOTA-D-phel-Tyr3-octreotide) and DOTANOC (DOTA-1-NaI-octreotide). The use of these radiotracers has recently increased because of their convenient preparation using a germanium-68/gallium-68 (68Ge/68Ga)
Fluorine-18–sodium fluoride
Fluorine-18–sodium fluoride (18F-NaF) is a highly sensitive PET tracer used for detecting skeletal osteoblastic abnormalities.11, 12 Fluorine-18–sodium fluoride is an analog of the hydroxyl ion in the bone matrix and is rapidly exchanged with high initial extraction fraction in the hydroxyapatite crystals. The uptake of 18F-NaF correlates with blood flow and bone remodeling; therefore, it is not tumor-specific and can be a viable option for studying different benign skeletal processes.13
Fluorine-18–labeled dihydroxyphenylalanine
Dihydroxyphenylalanine (DOPA) is a neutral amino acid analog to the dopamine precursor 3,4-dihydroxy-l-phenylalanine (l-DOPA). It is internalized by the amino acid transport system for large neutral amino acids and enters the catecholamine metabolic pathway of endogenous l-DOPA in the brain and peripheral tissue.17 It was first assembled with 18F for the study of Parkinson disease. Its use has recently been expanded to include imaging of some neuroendocrine tumors, primary brain neoplasias, and
Fluorine-18–flutemetamol
Flutemetamol (2-[4-(methylamino)phenyl]-1,3-benzothiazol-6-ol) is a neutral analog of thioflavin T. Multiple studies have confirmed the capability of this molecule to cross the blood–brain barrier and to reversibly bind fibrillar β-amyloid in the brain.22 Flutemetamol was initially labeled with an 11C isotope, limiting its availability because of the 20-minute half-life of the 11C. 18-Florbetapir is a similar agent, which tracks the amyloid deposits and has shown some promise in assessing the
Fluorine-18–fluoromisonidazole
Fluorine-18–fluoromisonidazole (F-MISO) is one of the most commonly used radiotracer for hypoxia. Misonidazole is a nitroimidazole and thus, after passive diffusion into the cell, is reduced with nitro anion radicals. In the presence of oxygen, the last reaction is reversible and the molecule can leave the cell, but in absence of oxygen, misonidazole is reduced and remains trapped in the cell.
Since the early 1980s, Misonidazole has been known to be not only a useful tracer for identifying
Cardiovascular molecular imaging applications
Positron emission tomography allows an accurate assessment of myocardial perfusion and coronary artery disease (CAD), and remains a valuable tool for the assessing myocardial viability in patients with severe left ventricular dysfunction. Positron emission tomography/computed tomography imaging allows a comprehensive evaluation of the functional and morphologic severity of CAD. Combining the ability of MRI to produce high-resolution anatomic images and the high sensitivity of PET for detecting
References (29)
- et al.
Glycerophosphocholine catabolism as a new route for choline formation for phosphatidylcholine synthesis by the Kennedy pathway
J Biol Chem
(2005) - et al.
Multimodality imaging in biochemical recurrence of prostate cancer: utility of (18)F-NaF PET/CT in early detection of metastasis
Rev Esp Med Nucl Imagen Mol
(2012) - et al.
Clinical utility of (18)F-fluoride PET/CT in benign and malignant bone diseases
Bone
(2012) - et al.
State of the art in nuclear imaging for the diagnosis of bone metastases
Bull Cancer
(2013) - et al.
PET imaging of cardiac hypoxia: opportunities and challenges
J Mol Cell Cardiol
(2011) - et al.
Metabolic markers of breast cancer: enhanced choline metabolism and reduced choline-ether-phospholipid synthesis
Cancer Res
(2002) - et al.
Evaluation of deuterated 18F- and 11C-labeled choline analogs for cancer detection by positron emission tomography
Clin Cancer Res
(2012) - et al.
Evaluation of the PET component of simultaneous [(18)F]choline PET/MRI in prostate cancer: comparison with [(18)F]choline PET/CT
Eur J Nucl Med Mol Imaging
(2014) - et al.
Brain tumors: detection with C-11 choline PET
Radiology
(1997) - et al.
NODAGATOC, a new chelator-coupled somatostatin analogue labeled with [67/68Ga] and [111In] for SPECT, PET, and targeted therapeutic applications of somatostatin receptor (hsst2) expressing tumors
Bioconjug Chem
(2002)
Gadoxetate-enhanced versus diffusion-weighted MRI for fused Ga-68-DOTANOC PET/MRI in patients with neuroendocrine tumours of the upper abdomen
Eur Radiol
Functional assessment in the multimodality imaging of pancreatic neuro-endocrine tumours
Minerva Endocrinol
Bone metastases in patients with neuroendocrine tumor: 68Ga-DOTA-Tyr3-octreotide PET in comparison to CT and bone scintigraphy
J Nucl Med
Physiological and tumoral uptake of (68)Ga-DOTATATE: standardized uptake values and challenges in interpretation
Ann Nucl Med
Cited by (7)
Precision medicine in oncology
2018, DeVita, Hellman, and Rosenberg's Cancer: Principles & Practice of OncologyNononcologic applications of PET/CT and PET/MRI in musculoskeletal, orthopedic, and rheumatologic imaging: General considerations, techniques, and radiopharmaceuticals
2018, Journal of Nuclear Medicine TechnologyACR and SNMMI joint credentialing statement for PET/MRI of the body
2017, Journal of Nuclear MedicineAssessment of skeletal tumour burden on <sup>18</sup>F-NaF PET/CT using a new quantitative method
2017, Nuclear Medicine CommunicationsTechniques, benefits, and challenges of PET-MR
2015, Radiologic Technology