The use of supraglottic airway (SGA) devices in pediatric patients with neck masses “almost always” has an effect on the appearance of the masses on MRI scans, according to a 10-year review at a single institution.
Results from analyzing the MRI scans from databases at the Children’s Hospital of Philadelphia (CHOP) support avoidance of SGA devices in children undergoing imaging studies—and potentially radiation therapy—for neck masses, the investigators concluded.
Noting the scant literature in this area, the investigators queried CHOP databases for patients under 18 years of age who had neck MRIs and had gone under general anesthesia: at least one MRI with an SGA device, and at least one MRI with either a natural airway or an endotracheal tube. Roughly 8,000 MRI scans were assessed by two reviewers to determine the effect the SGA device had on neck masses during MRI.
A total of 28 patients were found who met the inclusion criteria. Of these, 10 did not have neck masses, and six had masses in areas that the SGA device could not have affected. That left 12 patients with an airway device change and neck masses in areas that the SGA device could have affected, and in fact 11 of those 12 patients did have a documented change in the appearance of their neck masses resulting from use of an SGA device.
The investigators concluded that SGA devices “may affect the appearance of the submandibular, retropharyngeal and prevertebral cervical regions,” creating the potential for misdiagnosis and issues with treatment.
Impetus Was Quality Improvement
Vladislav Obsekov, an undergraduate at the University of Pennsylvania, in Philadelphia, who was involved with the study, said the findings were not wholly unexpected.
“We had an idea that this was happening, but we wanted to know if it was an isolated incident or whether it had been occurring frequently,” Mr. Obsekov said. “It was interesting to note that we weren’t the only ones who had found this. There were some cases where the attending anesthesiologist or radiologist would mark in the patient’s chart that the MRI scan may not depict the mass accurately because of the type of airway device used. So we had some clues.”
Allan Simpao, MD, MBI, an attending anesthesiologist in the Department of Anesthesiology and Critical Care Medicine at CHOP, who led the study, said he was surprised to see that in the vast majority of the dozen cases that met the study criteria, the images were affected to the point where the radiologist commented on the SGA device’s effect.
“I had expected some of these masses to not be as compressible as they were,” Dr. Simpao said. “I was surprised that we had as many cases as we did over the course of 10 years, and kept using the SGA afterwards.”
Dr. Simpao noted that the impetus for the study was a quality improvement meeting at CHOP during which his department decided to stop using SGA devices during MRI for neck masses. To his knowledge, the problem had not been discussed as a joint anesthesiology–radiology issue prior to that meeting.
“Patients usually come in for yearly MRI surveillance for growth of neck masses. Not infrequently we see these patients come back for serial MRIs, and it’s important we don’t choose airway devices that cause artifacts for radiologists as they monitor these masses,” Dr. Simpao said. The findings were presented at the 2017 meeting of the Society for Pediatric Anesthesia/American Academy of Pediatrics Section on Anesthesiology and Pain Medicine (abstract AIR-14).
He also noted that a relatively rigid SGA device was used for patients in this study (Ambu AuraOnce), and that a more flexible SGA device, such as the Ambu AuraFlex, might yield different results.
Narasimhan Jagannathan, MD, associate professor of anesthesiology at Northwestern University Feinberg School of Medicine and an anesthesiologist at Ann & Robert H. Lurie Children’s Hospital and Northwestern Memorial Hospital, all in Chicago, said the study findings show that anesthesiologists should be more aware of the compressibility of neck masses, and consider using an endotracheal tube or natural airway in patients undergoing MRI for neck masses.
“The numbers that they report are relatively small, and it’s unclear whether a large mass versus a small mass could still be possible to identify in the presence of an SGA,” Dr. Jagannathan said. “This is kind of a pilot analysis, and I think a greater amount of patients is needed to make more definitive conclusions on the findings.”
Dr. Jagannathan added that he would like to see further research on whether extension or flexion of the neck also could cause neck masses to present differently during MRI.
“It’s conceivable that if you have the patient in a fully extended position, the mass could appear to be smaller in size, for example,” he said. “If we’re able to quantify what kinds of masses may be compressible, that may help clinicians to manage these patients during the MRI scan.”