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Molecules (Basel, Switzerland) Oct 2022Molecular imaging is the visual representation of biological processes that take place at the cellular or molecular level in living organisms. To date, molecular imaging... (Review)
Review
Molecular imaging is the visual representation of biological processes that take place at the cellular or molecular level in living organisms. To date, molecular imaging plays an important role in the transition from conventional medical practice to precision medicine. Among all imaging modalities, positron emission tomography (PET) has great advantages in sensitivity and the ability to obtain absolute imaging quantification after corrections for photon attenuation and scattering. Due to the ability to label a host of unique molecules of biological interest, including endogenous, naturally occurring substrates and drug-like compounds, the role of PET has been well established in the field of molecular imaging. In this article, we provide an overview of the recent advances in the development of PET radiopharmaceuticals and their clinical applications in oncology.
Topics: Radiopharmaceuticals; Positron-Emission Tomography; Molecular Imaging
PubMed: 36296381
DOI: 10.3390/molecules27206790 -
Journal of Nuclear Cardiology :... Jun 2022
Topics: Heart; Heart Transplantation; Humans; Positron-Emission Tomography; Tomography, X-Ray Computed
PubMed: 33527331
DOI: 10.1007/s12350-020-02514-5 -
Chinese Clinical Oncology Apr 2024Positron emission tomography (PET) imaging has been useful in delineating tumor volumes and allowing for improved radiation treatment. The field of PET-guided... (Review)
Review
BACKGROUND AND OBJECTIVE
Positron emission tomography (PET) imaging has been useful in delineating tumor volumes and allowing for improved radiation treatment. The field of PET-guided radiotherapy is rapidly growing and will have significant impact on radiotherapy delivery in the future. This narrative review provides an overview of the current state of PET-guided radiotherapy as well as the future directions of the field.
METHODS
For this narrative review, PubMed was searched for articles from 2010-2023. A total of 18 keywords or phrases were searched to provide an overview of PET-guided radiotherapy, radiotracers, the role of PET-guided radiotherapy in oligometastatic disease, and biology-guided radiotherapy (BgRT). The first 300 results for each keyword were searched and relevant articles were extracted. The references of these articles were also reviewed for relevant articles.
KEY CONTENT AND FINDINGS
In radiotherapy, 18F-2-fluoro-2-deoxy-D-glucose (F-FDG or FDG) is the major radiotracer for PET and when combined with computed tomography (CT) scan allows for anatomic visualization of metabolically active malignancy. Novel radiotracers are being explored to delineate certain cell types and numerous tumor metrics including metabolism, hypoxia, vascularity, and cellular proliferation. This molecular and functional imaging will provide improved tumor characterization. Through these radiotracers, radiation plans can employ dose painting by creating different dose levels based upon specific risk factors of the target volume. Additionally, biologic imaging during radiotherapy can allow for adaptation of the radiation plan based on response to treatment. Dose painting and adaptive radiotherapy should improve the therapeutic ratio through more selective dose delivery. The novel PET-linear accelerator hopes to combine these techniques and more by using radiotracers to deliver BgRT. The areas of radiotracer uptake will serve as fiducials to guide radiotherapy to themselves. This technique may prove promising in the growing area of oligometastatic radiation treatment.
CONCLUSIONS
Significant challenges exist for the future of PET-guided radiotherapy. However, with the advancements being made, PET imaging is set to change the delivery of radiotherapy.
Topics: Humans; Positron-Emission Tomography; Radiotherapy, Image-Guided; Neoplasms
PubMed: 38711177
DOI: 10.21037/cco-23-143 -
Journal of Nippon Medical School =... 2017Molecular imaging implies the method capable of pictorially displaying distribution of target molecules and their relative concentration in space. In clinical medicine,... (Review)
Review
Molecular imaging implies the method capable of pictorially displaying distribution of target molecules and their relative concentration in space. In clinical medicine, where non-invasiveness is mandatory, diagnostic molecular imaging has been considered virtually identical to positron emission tomography (PET). However, there is another powerful, apparently underutilized molecular imaging, namely, proton magnetic resonance spectroscopic imaging (H-MRSI). The technique can detect target molecules endogenous in brain in virtue of their own specific resonance frequencies (chemical shift) and can create quantitative images of each molecule. H-MRSI is conventionally utilized for imaging relatively easily detectable molecules such as N-acetyl-aspartate or lactate. More recently, however, the method is extended into imaging of more challenging molecules such as glutamate or γ-aminobutyric acid (GABA). In this small review, we summarize basic concept of H-MRSI and introduce an advanced technique, i.e. chemical exchange saturation transfer magnetic resonance imaging (CEST MRI), which made realistic glutamate imaging in vivo possible.
Topics: Aspartic Acid; Diagnostic Imaging; Glutamates; Humans; Lactates; Molecular Imaging; Neurotransmitter Agents; Positron-Emission Tomography; Proton Magnetic Resonance Spectroscopy; gamma-Aminobutyric Acid
PubMed: 28978895
DOI: 10.1272/jnms.84.160 -
International Journal of Surgery... Oct 2017Numerous distant metastases were not detected preoperatively. Positron emission tomography (PET) has been used for oncology diagnosis recently. However, it remains... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Numerous distant metastases were not detected preoperatively. Positron emission tomography (PET) has been used for oncology diagnosis recently. However, it remains controversial whether PET modality is a more efficient way in detecting unresectable features for radical resection of pancreatic cancer (PC). This meta-analysis aims to validate the efficiency of PET modalities (including PET and PET/CT) in preoperative assessment of PC, and compare them with computed tomography (CT).
METHODS
PubMed, EMBASE, Science Citation Index and The Cochrane Library were searched to identify relevant studies. Both PET modality and CT had been performed for all the included patients. A meta-analysis was performed to compare the ability of PET modalities in detecting occult distant metastases and regional lymph nodes invasion with that of CT.
RESULTS
17 clinical studies that recruited 1343 patients were included. This meta-analysis indicated that PET modalities were more efficient in detecting true positive distant metastases compared with CT (OR = 1.52, 95%CI: 1.23-1.88). In subgroup analysis, when compared with CT alone, PET/CT also showed greater utility in detecting distant metastases (OR = 1.66, 95%CI: 1.31-2.08). There was no definite difference in detecting regional lymph nodes invasion between PET modalities and CT (OR = 0.97, 95%CI: 0.63-1.47).
CONCLUSION
Compared with CT, PET/CT provides extensive possibility to avoid futile radical resection by detecting occult metastases of PC preoperatively. Surgeons, especially in developing countries, should take PET modalities as a routine preoperative assessment before making operative plan for PC patients.
Topics: Humans; Lymph Nodes; Pancreatic Neoplasms; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Tomography, X-Ray Computed
PubMed: 28890410
DOI: 10.1016/j.ijsu.2017.09.003 -
International Journal of Molecular... Jun 2023Various papers have introduced the use of positron emission tomography (PET) with [Ga]Ga-radiolabeled fibroblast-activation protein inhibitor (FAPi) radiopharmaceuticals... (Meta-Analysis)
Meta-Analysis Review
Various papers have introduced the use of positron emission tomography (PET) with [Ga]Ga-radiolabeled fibroblast-activation protein inhibitor (FAPi) radiopharmaceuticals in different subtypes of gastric cancer (GC). Our aim was to assess the diagnostic performance of this novel molecular imaging technique in GC with a systematic review and meta-analysis. A straightforward literature search of papers concerning the diagnostic performance of FAP-targeted PET imaging was performed. Original articles evaluating this novel molecular imaging examination in both newly diagnosed GC patients and GC patients with disease relapse were included. The systematic review included nine original studies, and eight of them were also eligible for meta-analysis. The quantitative synthesis provided pooled detection rates of 95% and 97% for the assessment of primary tumor and distant metastases, respectively, and a pooled sensitivity and specificity of 74% and 89%, respectively, for regional lymph node metastases. Significant statistical heterogeneity among the included studies was found only in the analysis of the primary tumor detection rate (I = 64%). Conclusions: Beyond the limitations of this systematic review and meta-analysis (i.e., all the included studies were conducted in Asia, and using [F]FDG PET/CT as a comparator of the index test), the quantitative data provided demonstrate the promising diagnostic performance of FAP-targeted PET imaging in GC. Nevertheless, more prospective multicentric studies are needed to confirm the excellent performances of FAP-targeted PET in this cluster of patients.
Topics: Humans; Positron Emission Tomography Computed Tomography; Stomach Neoplasms; Prospective Studies; Neoplasm Recurrence, Local; Positron-Emission Tomography; Radiopharmaceuticals; Fluorodeoxyglucose F18; Gallium Radioisotopes
PubMed: 37373285
DOI: 10.3390/ijms241210136 -
American Journal of Rhinology & Allergy Sep 2023Positron emission tomography (PET) scan is a valuable imaging modality widely used in the management of cancers. Its usage is well defined for most head and neck... (Review)
Review
BACKGROUND
Positron emission tomography (PET) scan is a valuable imaging modality widely used in the management of cancers. Its usage is well defined for most head and neck malignancies. However, there is a lack of consensus regarding the utility of PET scan for sinonasal malignancies. This is highlighted by the latest international consensus statement on endoscopic skull base surgery.
OBJECTIVE
This systematic review aims to clarify the role of PET scan in the management of sinonasal malignancies.
METHODS
We conducted a comprehensive literature search using PubMed, MEDLINE, EMBASE, Web of Science, CINAHL, and Cochrane databases for research studies of interest. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) updated statement was used to guide the review.
RESULTS
In total, 1807 articles were assessed for eligibility. Thirty-nine original papers, published between 2004 and 2021, met inclusion criteria. Seven articles focused on the role of PET scan for inverted papilloma, 23 for sinonasal carcinoma, 4 for melanoma, and 3 for lymphoma, and finally, 3 articles focused on the use of specific PET scan tracers for sinonasal malignancies. Qualitative summaries for each potential role of PET scans were provided. In general, included studies were retrospective in nature with low level of evidence.
CONCLUSIONS
In general, and across all types of sinonasal malignancies, PET scan yielded positive results regarding detection and initial staging. It was also considered as the modality of choice for detection of distant metastases, except in the case of sinonasal lymphoma. PET scan's main limit resides in its inability to detect lesions in or close to the metabolic activity of the brain.
Topics: Humans; Positron Emission Tomography Computed Tomography; Retrospective Studies; Positron-Emission Tomography; Paranasal Sinus Neoplasms; Lymphoma
PubMed: 37229633
DOI: 10.1177/19458924231177854 -
European Heart Journal. Cardiovascular... Feb 2023Myocardial fibrosis is the heart's common healing response to injury. While initially seeking to optimize the strength of diseased tissue, fibrosis can become...
Myocardial fibrosis is the heart's common healing response to injury. While initially seeking to optimize the strength of diseased tissue, fibrosis can become maladaptive, producing stiff poorly functioning and pro-arrhythmic myocardium. Different patterns of fibrosis are associated with different myocardial disease states, but the presence and quantity of fibrosis largely confer adverse prognosis. Current imaging techniques can assess the extent and pattern of myocardial scarring, but lack specificity and detect the presence of established fibrosis when the window to modify this process may have ended. For the first time, novel molecular imaging methods, including gallium-68 (68Ga)-fibroblast activation protein inhibitor positron emission tomography (68Ga-FAPI PET), may permit highly specific imaging of fibrosis activity. These approaches may facilitate earlier fibrosis detection, differentiation of active vs. end-stage disease, and assessment of both disease progression and treatment-response thereby improving patient care and clinical outcomes.
Topics: Humans; Cardiomyopathies; Myocardium; Positron-Emission Tomography; Fibrosis; Molecular Imaging; Positron Emission Tomography Computed Tomography
PubMed: 36575058
DOI: 10.1093/ehjci/jeac242 -
Metallomics : Integrated Biometal... Oct 2022Non-invasive imaging techniques to dynamically map whole-body trafficking of essential metals in vivo in health and diseases are needed. Despite 62Zn having appropriate...
Non-invasive imaging techniques to dynamically map whole-body trafficking of essential metals in vivo in health and diseases are needed. Despite 62Zn having appropriate physical properties for positron emission tomography (PET) imaging (half-life, 9.3 h; positron emission, 8.2%), its complex decay via 62Cu (half-life, 10 min; positron emission, 97%) has limited its use. We aimed to develop a method to extract 62Zn from a 62Zn/62Cu generator, and to investigate its use for in vivo imaging of zinc trafficking despite its complex decay. 62Zn prepared by proton irradiation of natural copper foil was used to construct a conventional 62Zn/62Cu generator. 62Zn was eluted using trisodium citrate and used for biological experiments, compared with 64Cu in similar buffer. PET/CT imaging and ex vivo tissue radioactivity measurements were performed following intravenous injection in healthy mice. [62Zn]Zn-citrate was readily eluted from the generator with citrate buffer. PET imaging with the eluate demonstrated biodistribution similar to previous observations with the shorter-lived 63Zn (half-life 38.5 min), with significant differences compared to [64Cu]Cu-citrate, notably in pancreas (>10-fold higher at 1 h post-injection). Between 4 and 24 h, 62Zn retention in liver, pancreas, and kidney declined over time, while brain uptake increased. Like 64Cu, 62Zn showed hepatobiliary excretion from liver to intestines, unaffected by fasting. Although it offers limited reliability of scanning before 1 h post-injection, 62Zn-PET allows investigation of zinc trafficking in vivo for >24 h and hence provides a useful new tool to investigate diseases where zinc homeostasis is disrupted in preclinical models and humans.
Topics: Animals; Citrates; Copper; Copper Radioisotopes; Humans; Mice; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Protons; Reproducibility of Results; Thiosemicarbazones; Tissue Distribution; Tomography, X-Ray Computed; Zinc; Zinc Radioisotopes
PubMed: 36201445
DOI: 10.1093/mtomcs/mfac076 -
Nuclear Medicine and Biology 2023Cell death is fundamental in health and disease and resisting cell death is a hallmark of cancer. Treatment of malignancy aims to cause cancer cell death, however... (Review)
Review
Cell death is fundamental in health and disease and resisting cell death is a hallmark of cancer. Treatment of malignancy aims to cause cancer cell death, however current clinical imaging of treatment response does not specifically image cancer cell death but assesses this indirectly either by changes in tumor size (using x-ray computed tomography) or metabolic activity (using 2-[F]fluoro-2-deoxy-glucose positron emission tomography). The ability to directly image tumor cell death soon after commencement of therapy would enable personalised response adapted approaches to cancer treatment that is presently not possible with current imaging, which is in many circumstances neither sufficiently accurate nor timely. Several cell death pathways have now been identified and characterised that present multiple potential targets for imaging cell death including externalisation of phosphatidylserine and phosphatidylethanolamine, caspase activation and La autoantigen redistribution. However, targeting one specific cell death pathway carries the risk of not detecting cell death by other pathways and it is now understood that cancer treatment induces cell death by different and sometimes multiple pathways. An alternative approach is targeting the cell death phenotype that is "agnostic" of the death pathway. Cell death phenotypes that have been targeted for cell death imaging include loss of plasma membrane integrity and dissipation of the mitochondrial membrane potential. Targeting the cell death phenotype may have the advantage of being a more sensitive and generalisable approach to cancer cell death imaging. This review describes and summarises the approaches and radiopharmaceuticals investigated for imaging cell death by targeting cell death pathways or cell death phenotype.
Topics: Humans; Fluorodeoxyglucose F18; Neoplasms; Positron-Emission Tomography; Tomography, X-Ray Computed; Radiopharmaceuticals
PubMed: 37598518
DOI: 10.1016/j.nucmedbio.2023.108380