18F-fluciclovine (Axumin) PET/CT detecting occult bone metastasis

Molecular imaging of bone metastasis

Recent advances in molecularly targeted modular designs for in vivo imaging applications has thrusted open possibilities of investigating deep molecular interactions non-invasively and dynamically. The shifting landscape of biomarker concentration and cellular interactions throughout pathological progression requires quick adaptation of imaging agents and detection modalities for accurate readouts. The synergy of state of art instrumentation with molecularly targeted molecules is resulting in more precise, accurate and reproducible data sets, which is facilitating investigation of several novel questions. Small molecules, peptides, antibodies and nanoparticles are some of the commonly used molecular targeting vectors that can be applied for imaging as well as therapy. The field of theranostics, which encompasses joint application of therapy and imaging, is successfully leveraging the multifunctional use of these biomolecules [[1], [2]]. Sensitive detection of cancerous lesions and accurate assessment of treatment response has been transformative for patient management. Particularly, since bone metastasis is one of the dominant causes of morbidity and mortality in cancer patients, imaging can be hugely impactful in this patient population. The intent of this review is to highlight the utility of molecular positron emission tomography (PET) imaging in the context of prostate and breast bone metastatic cancer, and multiple myeloma. Furthermore, comparisons are drawn with traditionally utilized bone scans (skeletal scintigraphy). Both these modalities can be synergistic or complementary for assessing lytic- and blastic- bone lesions.

The location of metastatic lymph nodes and the evaluation of lymphadenectomy by near-infrared photoacoustic imaging with iridium complex nanoparticles

Histopathology evaluation and lymphadenectomy of node-positive patients is the usual procedure in clinical therapy. However, it requires days for the histopathology result analysis, which impedes intraoperative decision-making and immediate treatment. Noninvasive real-time imaging of metastatic lymph nodes can overcome these defects and help medical workers evaluate lymph nodes and make the operation decision more efficiently. Herein we developed iridium(III)-cyanine complex/bovine serum albumin (BSA)-based nanoparticles which are conjugated with folic acid (FA) (IrCy-FA NPs). The synthesized IrCy-FA NPs exhibit good biocompatibility, strong near-infrared absorption, and impressive lymph node accumulation and can serve as a photoacoustic (PA) imaging probe for lymph node imaging. Besides, the lymph nodes enriched with IrCy-FA NPs showing green color are easily visible to the naked eye, suggesting their potential as an intraoperative indicator. The real-time PA imaging with excellent contrast and high spatial resolution can promote efficient and reliable quantitative analysis of lymph nodes in vivo. By employing IrCy-FA NPs as the PA agent for lymph node imaging, we achieve effective pre-operative and post-operative evaluations of metastatic lymph nodes in lymphadenectomy. This study may provide helpful information for PA imaging guided colocalization and evaluation of lymph nodes and facilitate this method towards clinical trials.

Radiopharmaceuticals for PET and SPECT Imaging: A Literature Review over the Last Decade

Positron emission tomography (PET) uses radioactive tracers and enables the functional imaging of several metabolic processes, blood flow measurements, regional chemical composition, and/or chemical absorption. Depending on the targeted processes within the living organism, different tracers are used for various medical conditions, such as cancer, particular brain pathologies, cardiac events, and bone lesions, where the most commonly used tracers are radiolabeled with 18F (e.g., [18F]-FDG and NA [18F]). Oxygen-15 isotope is mostly involved in blood flow measurements, whereas a wide array of 11C-based compounds have also been developed for neuronal disorders according to the affected neuroreceptors, prostate cancer, and lung carcinomas. In contrast, the single-photon emission computed tomography (SPECT) technique uses gamma-emitting radioisotopes and can be used to diagnose strokes, seizures, bone illnesses, and infections by gauging the blood flow and radio distribution within tissues and organs. The radioisotopes typically used in SPECT imaging are iodine-123, technetium-99m, xenon-133, thallium-201, and indium-111. This systematic review article aims to clarify and disseminate the available scientific literature focused on PET/SPECT radiotracers and to provide an overview of the conducted research within the past decade, with an additional focus on the novel radiopharmaceuticals developed for medical imaging.

PET Molecular Imaging in Drug Development: The Imaging and Chemistry Perspective

Positron emission tomography with selective radioligands advances the drug discovery and development process by revealing information about target engagement, proof of mechanism, pharmacokinetic and pharmacodynamic profiles. Positron emission tomography (PET) is an essential and highly significant tool to study therapeutic drug development, dose regimen, and the drug plasma concentrations of new drug candidates. Selective radioligands bring up target-specific information in several disease states including cancer, cardiovascular, and neurological conditions by quantifying various rates of biological processes with PET, which are associated with its physiological changes in living subjects, thus it reveals disease progression and also advances the clinical investigation. This study explores the major roles, applications, and advances of PET molecular imaging in drug discovery and development process with a wide range of radiochemistry as well as clinical outcomes of positron-emitting carbon-11 and fluorine-18 radiotracers.