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Overview
What is Positron Emission Tomography (PET) molecular imaging?
Positron Emission Tomography (PET) is a non-invasive molecular imaging technology that visualizes and quantifies biological processes in vivo. Unlike conventional imaging modalities, which primarily reveal anatomical changes, PET detects labeled molecules (radiotracers) involved in specific biological pathways.
By acquiring longitudinal PET images over time, PET enables quantitative assessment of a therapeutic's biodistribution and pharmacokinetics. Advanced image analysis further provides quantitative measures of drug delivery, target engagement, residence time and clearance, offering a comprehensive understanding of therapeutic behavior in vivo.
What are the main steps in a PET molecular imaging study?
Every study follows the same four-step workflow. First, your therapeutic candidate is labeled using chemistry that preserves its biological integrity and pharmacokinetic profile. Next, longitudinal whole-body PET/MRI scans are acquired over the desired time window, with blood samples collected at selected time points to support pharmacokinetic analysis.
Following the final imaging session, ex vivo studies are performed to measure radiotracer concentration in tissues and organs, validating the in vivo findings. Then, TheraPET4D® generates quantitative biodistribution maps and kinetic parameters that comprehensively characterize the pharmacokinetics of your therapeutic. Finally, all study data are compiled into a comprehensive final report, providing a complete and transparent record of the project and its key findings.
How do we analyze PET images?
Rather than relying solely on conventional PET metrics that measure radiotracer uptake in a tissue at a single time point, we apply quantitative kinetic modeling to the complete longitudinal imaging dataset.
TheraPET4D® decomposes the PET signal into biologically meaningful parameters that describe the therapeutic's behavior in vivo, including radiotracer influx (drug delivery), specific target binding (target engagement), residence time and efflux (washout). This approach provides a far more mechanistic and quantitative understanding of biodistribution and pharmacokinetics than conventional static PET image analysis.
The four stages
Labeling Services
The therapeutic or delivery system is labeled with the most appropriate positron-emitting radioisotope, selected so that its physical half-life matches the biological half-life of the therapeutic or delivery system. Comprehensive quality control is then performed to ensure high radiochemical purity and specific activity. The structural integrity of the therapeutic or delivery system is verified to confirm that the labeling process has not caused fragmentation or degradation, while functional assays confirm that its biological activity and target-binding properties are preserved. Once all quality criteria are met, the radiotracer is ready for in vivo administration.
Molecular PET In Vivo Imaging
We provide longitudinal PET/MRI and PET/CT imaging to monitor the biodistribution and pharmacokinetics of the therapeutic agent or delivery system under evaluation. Imaging is initiated immediately after radiotracer administration, with customized whole-body acquisition schedules designed to meet your study objectives. Blood sampling is synchronized with imaging time points to enable comprehensive pharmacokinetic analysis. All scans are performed in live animals under carefully controlled anesthesia, adhering to the highest standards of animal welfare. Our protocols maximize data quality and reproducibility while ensuring minimal stress and discomfort for the animals.
Quantitative Image Analysis
Our proprietary quantification methodology comprises a comprehensive workflow designed to maximize the accuracy and reliability of PET imaging data. The process includes image reconstruction, followed by the extraction of radiotracer concentration over time from individual organs, which are precisely delineated using anatomical MRI or CT images. Radiotracer concentrations are then corrected using proprietary calibration (Q) factors derived from dedicated phantom studies, improving quantification accuracy across the entire field of view, including regions away from the scanner center. Time–radiotracer concentration curves are generated for each organ and fitted to advanced kinetic modeling approaches, incorporating blood-derived input functions obtained from synchronized blood sampling.
This integrated analysis enables the precise estimation of key pharmacokinetic parameters, including:
- Radiotracer influx rate (delivery) to individual organs and tissues.
- Specific target binding (target engagement), providing a quantitative measure of therapeutic interaction with the intended molecular target.
- Radiotracer efflux rate (washout), characterizing tracer clearance from tissues over time.
- Radiotracer residence time, quantifying the duration of radiotracer retention within individual organs and tissues, a key parameter for assessing drug exposure.
These quantitative biomarkers provide a robust assessment of drug biodistribution and in vivo pharmacokinetics, supporting informed decision-making throughout the drug development process.
Comprehensive Data Package
All study findings are compiled into a comprehensive final report, providing a complete and transparent record of the project. The report includes a detailed description of the study design, experimental procedures, image acquisition protocols, reconstruction methods and quantitative image analysis workflow. Results are presented through clear tables, graphs and high-quality images that facilitate data visualization and interpretation. Whenever appropriate, in vivo imaging findings are correlated with ex vivo analyses to strengthen the biological interpretation and reinforce study conclusions.
The final data package provides robust quantitative evidence to support the evaluation of your therapeutic candidate or delivery system and can be used to support regulatory submissions, scientific publications, investor presentations and decision-making throughout the drug development process.
Ready to start your molecular PET imaging study?
Schedule a technical consultation with the MIBIOTRACE team.