To perform xenon inhalation using the breath hold method, place a nose clip on the nose of the subject to facilitate breathing through the mouth. At the end of a normal exhalation to functional residual capacity, insert the mouthpiece of the xenon bag into the subject's mouth. Allow the subject to inhale 500 milliliters of xenon gas from the xenon bag.
Then remove the mouthpiece and instruct the subject to continue inhaling room air until the lungs are full. At the end of inhalation, ask the subject to raise their thumb. Request the nurse coordinator to verbally convey this information to the scanner operator to start the pulse sequence.
After the data acquisition period, instruct the subject to return to normal breathing. Move the subject out of the MRI scanner. Place a face mask over their nose and mouth.
Connect the hoses to the mask, and then connect the pre-fitted straps from behind the head to the mask and secure it in place. Move the subject to its original position inside the MRI scanner. Once the subject follows the breathing protocol, ask the nurse coordinator to inform the MRI operator to initiate data acquisition.
The nurse coordinator then opens the valves on the gas delivery system and the subject inhales 50 milliliters of hyperpolarized xenon 1-29 mixed with the airflow inside the breathing mask. Instruct the subject to continue breathing for approximately 10 breaths until the volume of xenon gas has been used up for the imaging protocol. Load the CSSR pulse sequence for free breathing.
Set the acquisition frequency according to the hyperpolarized xenon gas phase frequency determined during the calibration scan. Adjust the reference voltage to match the value obtained from the calibration scan. Select the wait for user option, or its equivalent, for sequence execution, following the system vendor's operating instructions.
Start the MRI scanner sequence. The scanner will pause for user input before data acquisition. Once the nurse coordinator switches the hyperpolarized xenon gas or air mixture, start data acquisition.
Ensure the sequence is already running before the subject inhales the first dose of xenon gas. After the three minute data acquisition, or exhaustion of hyperpolarized xenon gas, remove the subject from the MRI scanner. In the young, healthy female, the membrane signal increases rapidly due to the quick filling of thin walls.
In the older, lung transplant recipient, the membrane signal rises more gradually reflecting the longer time required to fill the thicker septal walls.
