Procedure may change biopsy approach for childrenTweet
By Mikie Hayes
Radiologist Dr. Paul Thacker, from left, joins Nalleley Mendoza-Perez and daughters, Hope and Zuanney, before Hope’s biopsy. photo by Mikie Hayes, Public Relations
A sweet and tiny Hope Mendoza–Perez had been having a rough year. In March, she was hospitalized with pneumonia. Then, late in the summer, her mother, Nalleley Mendoza, noticed Hope’s knee was swollen. Because of the pain, Hope preferred to crawl than to walk, and she would plop herself over on one side to avoid putting any pressure on the area that hurt her. The situation concerned Nalleley so she brought her toddler from Bluffton to MUSC to be seen.
Paul Thacker, M.D., a pediatric imaging expert and assistant professor in the Department of Radiology and Radiological Sciences, was called in to evaluate how best to determine what they were dealing with. Magnetic resonance imaging of Hope’s knee showed a mass within the distal femoral epiphysis, the lower femur, right next to the knee joint. Based on the MRI, the choices for diagnosis were either a tumor or an infection in the bone, both of which, according to Thacker, were exceedingly rare in a 16–month–old child.
Hope would need a biopsy and she underwent both an ultrasound and a computed tomography scan. The mass, however, was not apparent on either imaging study. While standard image-guided biopsy techniques in children are either done with ultrasound or CT, since the mass could not be seen on either study, Thacker could not use them to do the biopsy.
Thacker and Hope’s orthopaedic surgeon, James Mooney, M.D., professor of pediatric orthopaedic surgery, decided they had two options: Thacker could either perform a MRI-guided biopsy — which he could find no evidence had ever been performed on a child in the United States — or Dr. Mooney could go in and surgically try to resect it - which would be far more invasive and very difficult given the tiny size of the lesion, only 8 millimeters.
Thacker explained, “Standard extremity CTs generally provide significant anatomic information, particular when a mass is calcified.
However, Hope’s lesion was not and was invisible on CT. MRI demonstrates both anatomic and physiologic information, therefore, edema caused by a tumor or a noncalcified soft tissue tumor is more readily apparent. Plus, you can get a sense of what areas of a tumor may have higher yield on biopsy.”
Thacker decided to try the MRI route, given that the mass was only seen on MRI, even though this novel approach would be something completely out of the ordinary. He was excited about the prospects of testing it out. “I said to myself, ‘Yeah, we can probably do that!’”
While MRI-guided biopsies are performed fairly commonly in adults, such as in breast biopsies, this is not the case with children. As Thacker researched the subject, he was only able to find an example of the procedure being performed on children in Europe and Asia, and even then, it was rare and information sparse.
Even with the advances in CT scanning, such as faster scanning times and higher resolution images, the benefits of an MRI–guided biopsy are many. With MRI, Thacker would be able to precisely locate and remove cells from the suspicious areas for diagnosis and treatment planning; the procedure would be minimally invasive; and, unlike CT, the MRI uses no radiation.
One concern Thacker had prior to the procedure was the time it could take to perform it. CT is very quick and CT–guided biopsies are relatively short procedures. In contrast, MRI scans may last an hour or longer. He wouldn’t want it to take any longer, as a small child under anesthesia for a prolonged period of time is always a concern. There were some unknowns going in to the procedure, and Thacker would have to safely improvise with the equipment he had. However, if this MRI–guided biopsy were to go well, and the time was not much longer than what a CT–guided biopsy would take, it would be a monumental advancement in how children undergo image-guided biopsy.
Thacker said, “MRI–guided biopsies have been performed in adults, but not commonly for bone masses. Children, however, are another story entirely – to my knowledge it has only been performed a handful of times in the world. For one, it’s time-intensive and can take longer than other modalities; up to an hour. Also, there is less expertise on how to perform the procedure given its rare usage.”
Thacker continued, “This is extremely important for us. If we can safely and quickly do it in children, we can significantly reduce or stop doing CT biopsies and decrease radiation exposure to our children. Radiation is a huge concern and this would be a better choice. Radiation-induced cancer is a known risk. By using MRI, we could eliminate that risk.”
As Hope waited to go back for her procedure, she and her sister Zuanney, 3, played on the floor with a bright red shape-sorter and a Dora the Explorer doll while their mom stroked their hair and laughed at their antics. Hope, the more reserved of the two, watched her big sister twirl around and show off her sparkly jewelry to all admirers.
The very busy young girls listened intently as their mother spoke through her Spanish-language interpreter, sharing her confidence in Dr. Thacker and MUSC and her gratitude for the kind treatment she and her daughters had received from the doctors and nurses. “I feel special,” she said. “MUSC has been the best hospital. I am in a place where people are treating me so well and making me feel comfortable. Not having any family here, that is very important. I am so grateful for the kindness, and I feel very good being here.”
The Mendozas live in a small trailer in Bluffton, behind the home of Nallaley’s sister-in-law, Norma Manun, and her brother, Felipe’ Mendoza. “My family has been my support system and my backbone during such a stressful time,” she said.
When it was close to time for Hope to go back to pre–op, Zuanney held her little sister tightly. While Hope had no clue what was about to happen, everyone gathered around and hoped for a good outcome.
The procedure itself took 20 minutes. From the time Hope was put to sleep until she left the MRI suite was about an hour. The good news for all concerned was that Hope’s lesion was an infection which was easily treated with a course of antibiotics. She is under the care of Mooney showing marked relief from her symptoms after the procedure.
Thacker was pleased that the lesion was treatable with medicine rather than a tumor which would need to be resected. He was also equally excited about successful results of the procedure – especially what it means for the future. “It was fabulous,” he said. “The outcome was better than to be expected. I initially thought this would take significantly longer than a CT-guided procedure, but since the technical challenges were similar to that experienced in CT biopsies, and it took approximately the same amount of time, we will probably attempt to shift a majority of our children who would’ve had a CT-guided procedures over to the MRI-guided biopsy.”
“This case epitomizes the challenge and the joy of being a pediatric radiologist in a quaternary care center like MUSC Children’s Hospital,” said Jeanne Hill, M.D., director of the Division of Pediatric Radiology. “Collaboration is the key to improving patient safety, outcomes, and the quality of health care, and, as a division, we take great pride in our relationships with our clinical colleagues. I strongly believe that the collaborative efforts of MUSC clinicians and radiologists enable us to solve difficult diagnostic problems, like Hope’s, together in creative and innovative ways.”