Sinyeob, I, Andrew, and Callie ponder the MRI.
(Bryan Meltz)
We swapped the dogs’ collars for nylon ones. I had replaced the standard metal D-rings and clips on these leashes with plastic equivalents. Everyone did a double-check for metal in their pockets, like keys and cell phones, and for credit cards that would be erased if they got too close to the magnet. Normally, we would do the metal check in the control room at the scanner, but in order to avoid parading the dogs through the halls of the hospital, we would be entering the MRI room directly from outside through a side door. We needed to make sure everyone who was going to be in the room was MRI-safe.
At the scanner, we were greeted by Robert Smith, the tech who would run the MRI and who had been there for Callie’s dress rehearsal, and Sinyeob Ahn, a magnetic resonance physicist from China who would tweak scanner settings for us on the fly. They both smiled when they saw Callie and McKenzie, but I could tell neither of them thought this would actually work.
I heaved shut the vaultlike doors to the magnet room, creating a seal impenetrable by any form of electricity or radio waves. With the room secured and the doors locked, we let the dogs off-leash. Callie, of course, had been here before and knew that crumbs of food could be found on the floor of the control room. She gave only a passing glance at the magnet as she went off in search of something to eat. McKenzie gave the MRI her best border collie stare. Despite the susurrations of the cryogen pump, McKenzie soon realized that the magnet was not alive and could not be herded.
While Melissa worked with McKenzie to get comfortable around the magnet, I settled in with Robert and Sinyeob to plan the afternoon’s scans. Based on what we had learned from Callie’s dress rehearsal, we would implement several changes in the scan protocol.
From the control room I could see Melissa coaxing McKenzie into the scanner. Tentative at first, McKenzie carefully walked up the steps and plopped down on the patient table. She seemed unsure of what to do. Melissa went around to the other end of the magnet and, using some hot dogs, lured McKenzie in. As soon as Callie caught sight of that, she ran up the steps and climbed over McKenzie to stake out her position inside the magnet.
Sinyeob started laughing. “Look, two for one!”
McKenzie was not amused.
Turning to Helen, I said, “Could you get Callie and keep her out of the magnet until we’re ready?” Helen beamed, happy to have a job to do.
As had been done at the dress rehearsal, Sinyeob programmed three types of scans. The first would be the localizer image to see where the dog’s brain was. This would allow us to set the field of view for the subsequent scans. Next would come the functional scans.
“How long do you want to scan?” asked Robert.
For human studies, we normally scan in blocks of about ten minutes. That is about as long as a person can stay engaged in a task while in the scanner. We usually give the person a break of a few minutes and then repeat. I didn’t expect the dogs to stay in the scanner for that long, though.
“Let’s go with five minutes,” I said. With a complete scan through the brain taking two seconds, that would give us 150 images. Our goal was to get a consecutive sequence of ten images without movement somewhere in that block.
If we had time, and the dogs were up for it, the final scan would be a structural. It would be quick, but they would need to hold still for thirty seconds.
I turned to Andrew and said, “Are you ready?”
“Let’s do this!”
I looked at Callie and said, “Hey, Callie! Wanna do some training?” She jumped up to lick my face.
Melissa put McKenzie in a pup tent that she had brought. This let her relax while we worked with Callie.
Rebeccah followed Callie and me into the magnet room and took up a position at the end of the patient table where she could closely monitor Callie for any signs of distress. I slipped the earmuffs over Callie’s head and motioned for her to go into the magnet. As she shimmied in, I ran around to the back end so that I was facing her. Callie scooted into the head coil and placed her head on the chin rest.
“Good girl!” I said, and gave her a hot dog. She wagged her tail and looked at me expectantly. Meanwhile, Andrew had taken up a position just to my left. I glanced at him.
“Do it.”
Andrew raised his hand and pointed to Robert, who was observing through a glass window in the control room. The scanner came to life. Click. Click. Click. Then the buzzing of a million bees. The software, not recognizing a canine occupant, was beginning the shimming procedure to compensate for the distortion of the magnetic field that Callie’s canine form was causing.
Callie’s eyes narrowed to slits. I held up a piece of hot dog but it was already too late. She had started to back out. Further confused by the lack of anything inside it, the scanner continued buzzing for a few seconds until it gave up and aborted the sequence.
Rebeccah consoled Callie by stroking her chest. The earmuffs had slipped back and dangled uselessly around Callie’s neck.
I gave her some more hot dog pieces and repositioned the earmuffs to try again.
Callie went inside and once again assumed the sphinx position in the head coil. And once again, as soon as the scanner started shimming, she backed out.
After two more tries, I was beginning to get frustrated. I sat on the doggie steps and petted Callie on the head. She just looked at me as if to say, I’m trying.
Even with the extra training, the noise was worse than we had anticipated. Plus, the earmuffs kept sliding off. Maybe if we could get the earmuffs to make a better seal and stay on, the noise would be tolerable.
Rebeccah had the same thought. She rummaged through her vet tech gear and pulled out some gauze pads and a roll of nonadhesive tape—a clingy material called vet wrap. While I fed Callie a constant stream of hot dog, Rebeccah carefully placed a gauze pad between each of Callie’s ears and the earmuff. To keep it in place, Rebeccah wrapped her whole head with the vet wrap. Amazingly, Callie didn’t seem to mind this procedure. She ended up looking like she’d sustained a serious head injury, but the earmuffs were secure.
“Let’s try it again,” I said. Callie didn’t hear me, which was a good sign. I just motioned to the magnet, and she trotted in.
The magnet went through its click-whirrings, and I braced myself for the swarm of bees. I gave Callie some hot dog, and this time she stayed put. It seemed to go on forever. After thirty seconds, the buzzing was replaced by three brief klaxon sounds of the localizer. That meant the scanner had successfully shimmed the magnetic field and acquired an image. I gave Callie some more hot dog and ran to the control room to see what we had gotten.
Rebeccah giving Callie the wrap treatment.
(Bryan Meltz)
Callie wrapped and ready to rock!
(Bryan Meltz)