PET/CT With [⁶⁸Ga]-NOTA-FAP-2286 for Imaging of Tendon Injuries in Rat Achilles Tendon Injury Models

Our research investigates the potential of FAP targeted PET-CT imaging using NOTA-FAP-2286 for accurate detection and evaluation of tendon injuries. The latest advances in my research, it's the use of FAP-targeted PET-CT for precise imaging of tendon injuries. Current experimental challenges include optimizing tracers specificity, minimizing background signals, and correlating imaging findings with historic physiology.

To begin, secure an anesthetized rat onto a fixation board. With a scalpel, make a longitudinal incision to expose the Achilles tendon. Compress the tendon using hemostatic forceps until it is flattened.

Now close the incision with sutures. To establish the Achilles tendon rupture model, grasp the Achilles tendon with hemostatic forceps. Use surgical scissors to create a full thickness midline incision in the tendon, then suture the severed tendon and close the skin incision.

For PET imaging, secure the rat in a restrainer. Administer 500 microcurie of GA-68-NOTA-FAP-2286 via the tail vein to both groups of rats. Position the fully anesthetized rat in the scanning field with the Achilles tendon aligned at the center.

Turn on the computer connected to the small animal PET system. Now click on CT Acquisition to begin the preheating of the computed tomography system. Once the preheating is complete, select the scanning protocol, then open the corresponding scanning workflow, which has a preset scan duration of 10 minutes.

Click on Scout View to verify the Achilles tendon is at the center of the scanning field. If the positioning is accurate, click Start Workflow to initiate the PET and CT scans. Set the scan parameters NCT bed view from zero to 36.2 to 76.4 millimeters, CT scan time of 150 seconds per bed, and PET acquire by time set to 600 seconds.

Then set the photo peak energy level to 511 kiloelectron volt, lower level discrimination to 350 kilo electron volt, upper level discrimination to 650 kilo electron volt, and timing window to 3.432 nanoseconds. GA-68-NOTA-FAP-2286 showed a high radiochemical purity exceeding 95%Tracer uptake began at the site of Achilles tendon rupture or injury, 30 minutes post-injection, and intensified significantly over 90 minutes, showing higher signals compared to the surrounding muscle and the normal tendon. Computed tomography images failed to visually differentiate between injured ruptured and normal Achilles tendons, showing similar grayscale appearances across all samples.

Maximum intensity projection imaging demonstrated that GA-68-NOTA-FAP-2286 uptake on the injury or rupture side increased from the first week and peaked at the second week, indicating elevated fibroblast activation protein expression during tendon repair.