Advancing pediatric 
molecular imaging

When it comes to molecular imaging in pediatrics, one must remember that children are not simply small adults. Rigshospitalet in Denmark uses a PET/CT scanner that provides ultra-fast scan times and low-dose accommodations for young patients, often eliminating the need for sedation.

Data courtesy of Rigshospitalet, Copenhagen, Denmark

The impact of molecular imaging on modern healthcare has been nothing short of revolutionary. Techniques such as PET/CT, PET/MRI, and SPECT/CT have ushered in an era where clinicians can delve deeper into the human body, providing a clearer understanding of diseases and offering more precise methods for diagnosis and treatment. These technologies have drastically improved patient care by enabling clinicians to visualize diseases at a molecular level. However, when it comes to molecular imaging in pediatrics, one must remember that children are not simply small adults. Their unique needs and vulnerabilities necessitate a tailored approach.

At Rigshospitalet in Denmark, a medical institution renowned for its commitment to excellence in pediatric care, Dr. Lise Borgwardt and the team have been at the forefront of the evolving journey of molecular imaging in pediatrics since its introduction in 2000.¹ As Chief Physician in the Department of Clinical Physiology and Nuclear Medicine, subspecialized in pediatric nuclear medicine and PET, Dr. Borgwardt’s dedicated efforts have been pivotal in advancing patient care and diagnostics at this facility. This is only possible thanks to a close collaboration between dedicated technicians, doctors, physicists, and parents. Rigshospitalet is a crucial healthcare hub in Denmark and serves a vast pediatric patient community, providing care through 170,000 annual outpatient visits, 70,000 virtual patient visits, 13,000 surgeries, and 21,000 pediatric hospital admissions per year. Specifically, within molecular imaging, the Pediatric Nuclear Medicine and PET team conducts almost 2,500 pediatric exams per year.

Moreover, Rigshospitalet is currently in the process of constructing a new cutting-edge pediatric facility, Copenhagen Children’s Hospital (Mary Elizabeth’s Hospital—Rigshospitalet for Children, Teens and Expecting Families), set to open its doors in 2026. This children’s hospital, with a large, dedicated children’s diagnostic unit, underscores its commitment to continuing to provide state-of-the-art care and treatments for pediatric patients.

In pediatric oncology and beyond, PET/CT has become a cornerstone of diagnostic and treatment strategies. Clinicians in the pediatric team at the Department of Clinical Physiology and Nuclear Medicine at Rigshospitalet, led by Chief Physician and team leader of pediatric PET Kim Francis Andersen, MD, together with Dr. Borgwardt, encounter many oncology cases ranging from malignant lymphomas, soft tissue, and bone sarcomas to neuroblastomas and brain tumors. Beyond oncology, PET/CT also plays a pivotal role in multiple clinical areas, aiding in the precise diagnosis and monitoring of various conditions.

To serve these patients, Rigshospitalet has implemented advanced technology to optimize PET/CT scanning for pediatric patients. The majority of all pediatric patients are now scanned with Siemens Healthineers Biograph Vision Quadra™ PET/CT scanner. Recognized for its long axial field of view that allows ultra-fast scan times and the ability to realize low-dose accommodations for young patients, it was the right scanner for pediatric patients.^2,3 Together with Dr. Flemming L. Andersen and Professor Malene Fischer, MD, the team has developed dedicated protocols tailored to the specific challenges associated with pediatric PET/CT imaging.

“With 106-cm axial field of view,” said Dr. Borgwardt, “we can see all the patient’s organs in the same field of view. Biograph Vision Quadra gives us the ability to customize scans for each individual child. We can turn the scan time up and down, adjust injected tracer activity, and improve image quality to get an optimized scan for each child. And the short acquisition time of only a few minutes helps us to get young patients through scans without general anesthesia or sedation.”

“If we have a two-year-old patient with suspicion of a cancer diagnosis,” continued Dr. Borgwardt, “we try to optimize acquisition time and administered radiotracer activity, where we still have a chance to avoid anesthesia. Whereas if we have a 13-year-old patient, we can keep radiotracer activity very low because they can lay still for a longer period of time. This is how we maximize the new possibilities.”

As Dr. Borgwardt implied, using PET/CT in pediatric imaging is not without its challenges. Pediatric patients differ from adult patients in their psychology, normal physiology, and pathophysiology, factors that require additional consideration when planning scans.¹ Younger pediatric patients, often restless and unable to remain still for extended periods, have traditionally required general anesthesia or sedation during PET/CT scans.⁴ This practice not only poses potential risks but can also extend the duration of the procedure.

The team, with Dr. Borgwardt in the lead, has developed scheduling meta-[¹⁸F]fluorobenzylguanidine ([¹⁸F] mFBG) PET/CT protocols for different age groups, such as newborn to one year, one year to three years, and four years and older. To date, they have successfully performed 50 MFBG PET/CT scans of children using these protocols without any need for sedation or general anesthesia. This is only possible thanks to a close collaboration between dedicated technologists, radiographers, doctors, physicists, and parents.

Dr. Borgwardt and the team have published research showcasing their ability to refrain from sedating young patients for PET/CT scans, a significant departure from common practice.³ Their success in this endeavor has been attributed to the ultra-fast scan times, long axial field of view, and high sensitivity on the Biograph Vision Quadra system, coupled with a comprehensive protocol for scheduling pediatric patients. By working closely with families to schedule scans around nap times and feedings, the team can minimize patient radiation, avoid the need for anesthesia, and improve comfort and cooperation, all while maintaining image quality.

“Parents are contacted in advance, so we understand the child’s normal routines, and then we plan very specifically,” explained Dr. Borgwardt. “We try to maximize the schedule for our Biograph Vision Quadra, but if you want to scan children without sedation or general anesthesia in this very fragile group of youngsters, we book half an hour in advance on the scanner because the parents need to have time in the scanner room to help prepare their child. We schedule the scanner so the child can be fed in the scanner room. After feeding, the child is then wrapped, and the light is dimmed so the child can fall asleep. It can be complex, but it’s ultimately to get the best image that will provide the best diagnostics and thereby the best outcome for that patient.”

“There can also be some other factors depending on the tracer you use,” added Andersen. “Some tracers require fasting prior to injection, whereas others don’t need that. There are a lot of issues that we have to take into consideration when planning a scan. For many years, we’ve provided parents with a phone number to our specialist technicians, who are trained in pediatric exams. The parents always get written information, but if they feel the need for more information or to ask specific questions about how to prepare their child for the scan, they can call. Parents are also offered to visit the department and see the scanner beforehand if the child is still anxious. The child can try lying on the scanner bed and be driven in the scanner gantry, if necessary. If there is something that’s causing anxiety, we always want to address those issues and allay those fears, even if it takes up scan time.”

A paramount concern for pediatric patients undergoing multiple scans over time is the cumulative radiation exposure since the survival of children with cancer has increased over the last two decades.

“Today, the majority of pediatric patients with cancer are surviving,” Borgwardt explained, “but the radiation used to diagnose and cure a child can also cause secondary malignancies—cancers developed due to the radiation exposure—so minimizing the radiation for all our examinations is therefore very important in order to give the children with cancer the best opportunity to become long-term survivors.”

Andersen continued, “and therefore, we have reduced injected tracer activity for all pediatric fludeoxyglucose injection F 18 (FDG) PET/CT-scans to a standard of 1.5 MBq/kg on the Biograph Vision Quadra PET/CT, still scanning for only five minutes. This change in procedure plays a significant role in minimizing the cumulative injected radiotracer activity for our pediatric patients.”

In children with neuroblastoma, the most common type of extracranial cancer in children, most children get the disease before the age of five.⁵ “Follow-up protocols are dependent on the disease, and for neuroblastoma, patients are typically scanned five times or more,” said Dr. Borgwardt. “These scans are the standard diagnostic work-up performed with SPECT/CT using [¹²³I]-meta-Iodobenzylguanidine [¹²³I]mIBG tracer, but now we are also scanning with PET/CT using ¹⁸F-mFBG in a current clinical study in order to compare."

“Patients who have experienced both are very excited about the Biograph Vision Quadra,” added Andersen. “They’ve gone from a two-and-a-half hour scan to a five-minute scan, where it’s only one hour between radiotracer injection and scan.”

By having an onsite radiopharmacy, the Rigshospitalet team is able to produce many imaging agents, such as FDG, which is standard for oncology imaging, as well as newer agents, such as [¹⁸F]mFBG for neuroblastoma imaging research. “[¹⁸F]mFBG is an extremely promising tracer for neuroblastoma patients, and it’s not standard of care yet,” explained Dr. Borgwardt. “The resolution is three times better, going from SPECT to PET due to the change in imaging modality, but then increased twenty-fold from our previous PET studies because of the technology behind Biograph Vision Quadra. We really see an enormous increase in the resolution, and we know it will be a game changer.”

Biograph Vision Quadra’s potential to change patient outcomes was readily apparent when a pediatric patient with neuroblastoma was initially scanned with [¹²³I]mIBG at diagnosis and, due to the team’s prospective clinical study, also scanned with [¹⁸F]mFBG on Biograph Vision Quadra PET/CT.

“The standard scan [¹²³I]mIBG SPECT/ CT had shown a thoracal tumor with no additional lesions,” explained Dr. Borgwardt. “This is typically the scan used to inform the patient’s treatment. However, on Biograph Vision Quadra, the images showed additional lesions that had spread to the bone marrow. This significant discovery resulted in the patient receiving different treatment. Without Biograph Vision Quadra’s images, the patient would have received less and most likely insufficient treatment with an increased risk of relapse.”

In all pediatric cases, scan procedures are individually optimized for the best outcome and image quality. Rigshospitalet also addresses radiation concerns by utilizing proprietary research artificial intelligence-software to generate a synthetic CT, which can be used exclusively for PET attenuation correction.^a This innovative approach and sophisticated software were developed at the department at Rigshospitalet and enable the team to minimize radiation exposure without compromising diagnostic accuracy.

As molecular imaging continues to evolve, the role of precision medicine in pediatric patient care becomes increasingly prominent. Imaging techniques like PET/CT are instrumental in providing invaluable insights into the diagnosis, treatment, and follow-up of pediatric diseases. The optimization of these imaging methods, as demonstrated by Rigshospitalet’s pioneering efforts, ensures each young patient receives tailored, safe, and effective care. 

The dedication of the clinical team in pediatric molecular imaging at Rigshospitalet is a testament to the unwavering commitment of healthcare professionals to advance patient care. With cutting-edge technology and a patient-centric approach, Dr. Borgwardt, Dr. Andersen, and their team have set a new standard for pediatric PET/CT imaging, and their work serves as a beacon, illuminating the path toward better outcomes and improved quality of life for pediatric patients.

Claudette Lew is a freelance medical writer and editor and writes frequently for Nuclear Medicine News & Stories.