Semi-quantitative Assessment Using [¹⁸F]FDG Tracer in Patients with Severe Brain Injury

This list can help us with key questions in the neuro-rehabilition field. Regarding Unresponsive Wakefulness Syndrome and minimal conscious states following cerebral traumatic brain injury. The main advantage of this technique is that, patients with brain tissue deformation such as, atrophy, swelling, enlargement and shrinking of ventricular spaces can be assisted in the chronic stage.

Demonstrating the procedure will be Tomoki Uchida, our pharmacist, Kazuaki Yokoyama, our skilled operator, Mizuho Kamezawa, our nurse, Shinji Onodera and Yoshihiro Ozaki, Radio Technologist from my laboratory. Begin manufacturing reagent kits for the automated production of FDG, tailored to the synthesizer in use. Set the syringes for the manufacturing reagent kits on to the corresponding syringe drivers in the automated FDG Synthesizer.

Be sure to use the automatic program to check the mobility of the pumping system. Check the volume of the Oxygen-16 and 18 water, and the volume of helium, hydrogen and nitrogen gases. Also ensure that the tap water is under 25 degrees celsius for primary cooling and under 22 degrees celsius for secondary cooling.

After one hour, ensure that air cannot leak from the reagent kit. Set out vials of acetonitrile, mannose triflate, ethanol, and PH buffer solution. Begin preliminary irradiation of Oxygen-16 in the cyclotron.

Check that two to three milliliters of water is irradiated in optimal conditions in the target area. Next, begin the irradiation of Oxygen-18 water in the cyclotron 90 minutes after starting. Set the bombardment time for up to 20 minutes, and the energy of the impinging protons to 16.5 mega electron volts.

Ensure that the lamp lights up, when the cyclotron is running. After irradiation, use helium gas to transfer two to three milliliters of the Oxygen-18 water from the cyclotron to the polypropylene receiver of the FDG Synthesizer. Hook syringes on to the corresponding syringe drivers and the pressurized reagent vials.

Then, dissolve the mannose triflate in one vial of 99.5 percent pure acetonitrile, then rinse the cassette with acetonitrile. Transfer the irradiate Oxygen-18 water to the FDG synthesizer. Then, after transferring the eluent to the containing Fluorine-18 without liquid into the reaction vessels.

Allow the solvents to evaporate until dry. During the drying process, add 80 microliters of acetonitrile to the reaction vessel three times. Perform the evaporation at 95 degrees celsius under nitrogen flow and vacuum.

Dissolve 25 milligrams of mannose triflate precursor in about 3.5 milliliters of 99.5 percent pure acetonitrile, then add it to the dry residue. A nucleophilic substitution reaction occurs at 85 degrees Celsius in the FDG Synthesizer. As a preliminary purification, mixed the labeled solution with 26 milliliters of distilled water.

Then, send about four milliliters of the diluted labeling solution back to the reaction vessel to recover the remaining activity. Next, pass the solution through the reverse phase cartridge. Then, rinse the cartridge containing the trapped labeled precursor four times using distilled water.

Now, convert the acetylated compound into FDG within the cartridge via alkaline hydrolysis. Using 750 microliters of 2 N sodium hydroxide for 90 seconds at room temperature. After hydrolysis is complete, collect the alkaline FDG solution in 70 milliliters of water, and mix it with a neutralization solution.

Then, purify the resulting neutralized FDG solution. Pass the neutralized FDG solution through a second reverse phase cartridge retaining the partially hydrolyzed compounds and non-bipolar byproducts. Then, pass it through an Alumina-N cartridge retaining the last trace of unreacted F-18 flouride ions, then pass it through a 0.22 micrometer filter.

Next, rinse the cassette and cartridges and filter with 3 milliliters of water to recover the residual FDG in the lines. Then, drain the FDG into the final vial which should contain 15 to 17 milliliters of liquid. After two hours and 30 minutes from start of preparation, perform a qualitative analysis by examining the vial to confirm that it is transparent without particles.

Also, measure the amount of liquid using a robe revolves balance. And measure the radioactivity and half-life using a radioisotope dose calibrator. Now, measure the PH as well as the residual cryptand-22 using test paper.

Also, measure the endotoxins with the appropriate device through the absorbance measuring. Next, dispense 0.5 milliliters from the vial and perform a radiochemical purity test via carbohydrated analysis. Use columns of 3.9 by 300 millimeters for high performance liquid chromatography to detect the peak radioactivity.

Finally, fill the vial covered by lead and tungsten with the FDG Tracer, at a dosage of 5 megabecquerel per kilogram of body weight. Then, three hours and 25 minutes after the start time, transfer the Tracer from the Hot Lab to the working room. Begin by preparing the intravenous route for the FDG Tracer administration.

Secure a 22 to 24 gauge needle with 5 milliliters of heparin sodium, on one of the lower limbs. The patient should then lie down for 30 minutes before entering the radiation controlled area. Next, recheck the patency of the intravenous route by drawing blood and measure the patient's blood glucose level.

Then, transfer the FDG Tracer from the Hot Lab to the working room through the window. Set the tracer up in the Auto Dispensing and Injection System. Check the aspiration of the FDG Tracer from the vial on the monitor.

Connect the tube between the patient and the Auto Dispensing Injection System. Push the bottom and inject the FDG Tracer to the patient. At this point, stop to confirm the Tracer amount and lot number, programmed radioactivity, injection time, injection speed, and measured radioactivity level.

Now, record the automatic measurement of pre-injected radioactivity that appears on the display of the Auto Display and Injection System. Then, inject the Tracer via the intravenous route at three hours and 30 minutes, after the start. Have the patient wait in the waiting room of the radiation controlled area for 50 minutes.

Then, four hours and 30 minutes after the start time, transfer the patient from the waiting room to the PET/CT machine, and record brain images for 10 minutes. After imaging, check the injection area for extravasation. Once all data is acquired, evaluation all image data for a standardized uptake value measurement using imaging software and compare the clinical assessment with the FDG-PET/CT images.

This figure shows a representative FDG-PET/CT brain image. Shown here is the measurement of the right thalamic glucose metabolism in a 3-dimensional image browser. Here we see a representative color mapped image after FDG-PET and CT fusion.

The blood glucose level at the time of the scan as depicted as red with a 50 percent SUV max threshold. This panel, shows representative 3-dimensional brain surface FDG-PET images. The red regions have a higher glucose metabolism than the green regions.

The blood glucose level at the time of scan is shown in red. While attempting this procedure, it's important that bombardment time and energy are adjusted according to the number of patients. Also, attention should be paid to the cryptand-222 tube, because it can be easily become stopped up by crystallization.

Also know that the hook of syringes should be handled carefully because it can be easily broken. In addition, be aware that a patient with cerebral traumatic brain injury can sometimes make unforeseen movements during image acquisition. Follow this procedure, add in many ways various radioactive tests can be applied in order to answer additional questions involving amino acid metabolism.

Don't forget that working with radioactive materials can be extremely hazardous and precautions such as radiation protection should always be taken while performing this procedure.