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Clinical use of combined PET/MR imaging

Bella with her pediatric oncologist Frederick S. Huang, MD, and her mother, Orshi Simmons

 

Combined PET/MRI — a relatively new technology available at just a handful of centers across the country — has been used mostly in research. Now that’s changing, and physicians at Mallinckrodt Institute of Radiology are leading the way in using this hybrid imaging tool in clinical care.

Young patient Bella Simmons is one of the first to make use of PET/MRI at Mallinckrodt. Diagnosed with rhabdomyosarcoma (RMS) — a disease in which malignant cancer cells form in muscletissue — before she even started kindergarten, Bella received expert multispecialty care at Washington University Medical Center and is cancer-free today. Hybrid imaging with PET/MRI was a key component of her tumor surveillance during therapy.

 

Using PET/MRI to scan pediatric patients has been successful due to collaboration among disciplines. Pediatric radiologist Geetika Khanna, MD, leads the effort, working with other MIR radiologists, nuclear medicine physicians, CCIR (the Center for Clinical Imaging Research, led by director Pamela K. Woodard, MD) staff, pediatric oncologists, and the pediatric anesthesia team. Together, these groups have created a workflow that allows children to be simultaneously scanned using both MRI (detailed images of soft tissue in the body) and PET (use of an injected substance to show radioactivity in the body).

“It’s exciting to see new technology such as PET/MRI benefit the youngest of our patients,” says Woodard. “At Mallinckrodt, our goal is to pursue and provide the best in imaging at the lowest radiation dose possible.”

It truly is a collaborative effort. After imaging is complete, the radiologists and nuclear medicine physicians read the MRI and PET scans respectively. Then the two specialists sit down together to compare notes before sending their findings to Bella’s oncologist.

Another benefit of PET/MRI is that by eliminating the need for a CT scan, the radiation dose to the child can be decreased by up to 40 percent. For younger children, it also means having to undergo anesthesia just once instead of twice. However, the latter isn’t an issue for Bella.

“Even at the young age of 8 years, Bella does an amazing job of holding still for her PET/MR scans without sedation,” says Khanna, who since February has been interim chief of Mallinckrodt’s pediatric radiology section. Khanna anticipates that the technology eventually will have a significant impact in the care of all pediatric oncology patients.

“Bella’s tumor had already seen an aggressive treatment regimen when it relapsed in her head and neck, so we knew that sorting out new cancer from old scar was going to be a challenge,” says pediatric oncologist Frederick S. Huang, MD. “The availability of a PET/MRI machine allowed us to deliver and monitor a new plan of chemotherapy, surgery, and radiotherapy with confidence.”

 

ABOVE: Mallinckrodt radiologists (l-r) Geetika Khanna, MD,
Pamela K. Woodard, MD, and Farrokh Deshdashti, MD 

 

 

Bella's Story

 

Bella was nearly 4 years old when her parents took her to an urgent care facility for a mass that had developed under her right ear. At the time, the Simmons lived in Fort Campbell, Kentucky, where her father, Dexter, a U.S. Army captain, was stationed. Bella was treated for an ear infection, but antibiotics proved to be of no help.

That routine trip morphed into something for which no parent is truly prepared. Her pediatrician wasn’t sure what was happening, but thinking that perhaps there was a malformation in Bella’s ear, sent her to Vanderbilt University in Nashville, Tennessee. While Bella’s blood work looked good, the otolaryngologist there ordered an ultrasound that showed something else. An MRI and biopsy soon followed. 

After several weeks of imaging to form a diagnosis of RMS, Bella started treatment in early 2012. She and her mother, Orshi, spent three weeks in Nashville while Bella underwent three chemotherapy sessions. At that point it was determined that she also needed proton therapy (more precise, since the tumor was close to Bella’s brain), so the duo moved to MD Anderson Cancer Center in Houston for six weeks so that Bella could receive that and chemotherapy simultaneously. They then returned to Vanderbilt.

All told, Bella endured more than a year of treatment and participated in a clinical trial studying the chemotherapy drug vincristine. It was rough; while Orshi remained with Bella, who was weak, tired, and vomiting, she was separated from her husband and older daughter.

The upside was that the tumor rapidly began to shrink, although subsequent scans showed it never disappeared completely. Surgery was not recommended at that time, and 11 months later the tumor came back — this time growing much more quickly.

By then the family had moved to Fort Leonard Wood, Missouri, and the largest nearby town —Springfield, Missouri — didn’t have an RMS specialist. Their previous physician recommended St. Louis Children’s Hospital and pediatric oncologist Frederick S. Huang, MD.

“Our previous pediatric oncologist had been so compassionate that I had a hard time trusting the ‘new guy,’” says Orshi. “But Dr. Huang is really knowledgeable and very patient-oriented. We have become friends with him and the staff — they love us and we love them.”

Bella resumed an aggressive chemotherapy campaign, one that left her feeling constantly sick and led to several emergency room admissions. To further complicate matters, it was at this time that Orshi was diagnosed with breast cancer. With her family living in Europe and her husband working, there was really no one available to help except her older daughter, Anna, just 12 at the time.

Orshi underwent a double mastectomy and is now cancer free. Bella and the family were advised that she should have surgery to remove the remaining tumor.

Seven-year-old Bella underwent the 12-hour surgery, followed by another round of radiation and a weekly, less aggressive chemotherapy regimen. After that, she initially traveled to St. Louis every three months to be scanned. She has done very well overall, although she has a mild form of Bell’s palsy — a paralysis or weakness on one side of the face — that is only noticeable when she talks or smiles.

Bella does smile — a lot — on her monthly follow-up visits to Children’s and the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. “Bella likes all the staff; she jokes with them,” says Orshi. “She’s very personable — a people person.”

Bella has had four PET/MR scans since the technology became available for clinical use. This technology, so valuable in diagnosing what is going on in the body, is well-suited for monitoring cancer over time. At her most recent appointment, in April 2016, Bella’s scans were clear.

“The results speak for themselves,” says Huang, associate professor of pediatrics. “Bella is a happy and vibrant young girl who remains free of rhabdomyosarcoma one year after completing all of her therapies!”

That’s great news for Bella, who recently turned 9, and this summer will be traveling to Hungary to visit her maternal grandparents.