Speed is critical for young patients, but some critics say “not so fast.”

Determining the best radiological tool for patients is the great challenge and reward of working in and around radiology. But when it comes to pediatric patients, the issues, risks, and anxieties increase exponentially.

It’s no wonder, then, that new modalities for imaging with pediatric patients can often be greeted with a mix of hesitation and excitement. While some tout the advantages of a new tool, others worry about the potential for unforeseen problems. The introduction of PET imaging for pediatric imaging has created just such a divergence in the industry.

Challenges of Pediatric Imaging

Obtaining medical images with pediatric patients presents a number of well-known challenges. Overall, structures within the body are smaller, making it difficult to encapsulate and envision both healthy and diseased portions of the body. In addition, the need for speed with pediatric patients is significant. First, speed of detection is crucial. Identifying problem areas and signs of disease as early as possible leads to better outcomes with all patients, but especially children. Earlier detection means avoiding invasive procedures that can have much more dangerous side effects with pediatric patients. Speed of imaging is also a pressing issue. Capturing images of pediatric patients is difficult due to their age and their inability to stay still for prolonged periods of time. Faster imaging mechanisms mean children aren’t taxed, and it means avoiding sedation during imaging.

So speed is critical for effective pediatric imaging. But so is quality in order to effectively measure those smaller body structures and detect problems early. Finding mechanisms that allow both speed and quality can be difficult for radiologists and referring physicians. Added to this overarching demand? The other major challenge of imaging with pediatric patients: the need to keep radiation dosing low. Taken all together, the whole endeavor of pediatric imaging seems fraught with impossibility.

It’s this last issue of radiation that presents one of the major sticking points when it comes to selecting imaging methods for pediatric patients. Extra radiation from medical imaging is always a concern for adults, representing additional risk for a number of physical ailments and long-term diseases. For children, the concern is much greater.

According to Image Gently, a campaign from the Alliance for Radiation Safety in Pediatric Imaging, approximately 7 million CT studies are performed on children every year in the United States, and the number is increasing by approximately 10% each year. As radiologists know well, CT is the largest contributor to medical radiation dose in the United States. The extra radiation from medical imaging like CTs has been shown in some studies to contribute to increased cancers in adults. With children, the tissues are more radiosensitive, meaning they receive a larger effective dose for a given level of radiation. Children also have a longer time to develop cancers from radiation exposure, and the risk of developing and dying from cancer increases exponentially for children.

Considering all of these challenges and the significant risks posed by imaging to children, radiologists and referring physicians can be at a loss as to how to proceed. Image Gently is a proponent of simple alterations to technique that can dramatically lessen the amount of radiation during CTs, including scanning only the specific area, reducing tube output, performing single-phase studies, and using breast shields for young girls. But one option that has yet to gain major traction in the medical community is the use of PET imaging in pediatric patients.

Mysteries and Misconceptions

PET imaging is an attractive alternative for many physicians and radiologists with pediatric patients. But it’s still shrouded in confusion, controversy, and high costs for many in the medical industry.

The benefits represented by PET imaging in pediatric populations are direct solutions to the major challenges of capturing pediatric images. First, and perhaps most important, the method involves relatively low doses of radiation. This fact in and of itself draws much support from proponents and users.

“The radiation burden of imaging, and particularly PET imaging, has been studied very aggressively,” said Partha Ghosh, MD, clinical marketing manager, molecular imaging, Siemens Medical Solutions USA Inc. “PET imaging actually offers a relatively minor dose, one less than other modalities. With new technological advances and products, the dose has been reduced quite dramatically. It’s really quite an advantage to pediatric imaging.”

In addition to the low dose of radiation emitted during imaging, PET offers exceptional speed and sensitivity. The tool offers quick scanning that allows children to avoid sedation and uncomfortable sittings. At the same time, the necessary quality is there along with the speed. PET imaging is precise and sensitive enough to effectively detect disease at an earlier stage than other methods, allowing for the earlier intervention needed with pediatric patients and the prevention of unnecessary procedures. The accuracy and sensitivity also allows radiologists and physicians tremendous power in monitoring the progress of disease in pediatric patients.

“PET is a very important diagnostic imaging tool,” said S. Ted Treves, MD, chief of the Division of Nuclear Medicine at Children’s Hospital Boston and professor of radiology at Harvard Medical School. “It provides a unique and effective way of assessing the extent of disease, and helps guide the selection of therapy. It can also assess the effect of therapy in a very sensitive way, and provides early detection to determine if disease activity has responded to therapeutic interventions.”

Experts say one of the biggest benefits of using PET on pediatric patients is that the method involves relatively low doses of radiation.

Despite the very real advantages represented in PET imaging for pediatric patients, market utilization seems to be low. Some suggest that PET imaging may in fact be in use in a significant amount of imaging centers and hospitals, but recording and billing are not specific enough to reflect this. Others contend that underutilization, and outright resistance to the method, is the status of the day.

Why does the medical community hesitate in using PET imaging for pediatric patients? Costs can be considered high, with reimbursements tied up in complex mechanisms. But the overarching consensus seems to be that physicians hesitate due to a general lack of knowledge about the advantages of this modality. Physicians are righteously concerned about radiation for their pediatric patients, view PET imaging as an unnecessary addition to clinical care, and do not understand the potential benefits afforded by PET imaging.

“Pediatric physicians are united in their desire to keep radiation exposure at a minimum,” said Joni Hanson, global product manager PET/CT. “But we find that some physicians think PET/CT is a research modality or doesn’t apply to pediatric patient populations. We need more education among physicians as to the benefits of PET/CT imaging. Education is key for physicians and the general public about the value of PET/CT imaging and what it brings to the treatment plan and overall care.”

Another issue potentially preventing higher utilization of PET imaging for children is a lack of protocols and standards. For specific indications, there is relatively little guidance for physicians and radiologists for the use of this type of imaging. Overall, there is also a lack of standards when dosing children with any nuclear medicine technique. In fact, a recent study led by Treves, published in the Journal of Nuclear Medicine, revealed that the use of radiopharmaceuticals with children is highly varied among pediatric hospitals, resulting in ineffective imaging and/or too much radioactive dosing.

Uses and Tools

To gain greater acceptance of PET imaging with pediatric patients, companies and users advocate education on the benefits of using the tool as well as demonstration of cost-effectiveness. Companies producing PET tools have begun initiatives involving the sharing of best practices among users, exposing hospitals and physicians to the value of the method. Through Web-based case studies and the gradual development of protocols, companies hope to increase communication about PET with children, and improve imaging with pediatric populations.

Proponents of PET imaging with children are eager to share their successes. Treves utilizes the imaging tool with pediatric cancer, epilepsy, and skeletal disorders, all to great effect.

“PET is very sensitive to the presence of active tumors in children, and provides a good way of assessing the extent of the tumor and the presence of metastases,” Treves said. “Once a tumor is discovered, PET can help guide us to the best sites for biopsy or directed therapy. It also helps with the assessment of disease monitoring and can provide early detection of residual or recurrent tumor activity.

“In the assessment of epilepsy, PET is again a very important tool,” Treves continued. “It noninvasively detects areas in the brain where seizures originate. In this context, PET also has a role in determining whether the patient is a candidate for surgery. Finally, PET with fluorine-18 sodium fluoride (NaF) is very useful in the detection of skeletal disorders, both in diagnosing bone stress in athletes and determining the extent of tumors in bone.”

The uses of PET imaging in pediatric patients are increasing with the evolution of the tools available.

GE Healthcare has offered a series of PET imaging tools, the most recent being the Discovery PET/CT with Dimension. The machine offers users one scanner and console that can perform both types of imaging exams at the radiologists’ discretion. The Discovery utilizes simultaneous whole body motion PET with comprehensive diagnostic CT techniques, offering real-time image reconstruction in a single exam. The goal is to provide the speed and quality necessary for all patient populations, with improved clarity, reduced dose, and increased flexibility. This flexibility is the key to its utilization with pediatric populations.

“We’ve introduced several features that help physicians use the most appropriate imaging method for that patient, and reduce the dose as much as possible,” said Henry Hummel, general manager, global PET/CT business, at GE. “Physicians and radiologists have the flexibility to use the best techniques for their pediatric and adult patients, without sacrificing study quality. We’ve also included CT protocol options for pediatric patients, specifically, color-coded protocols, to facilitate standard techniques appropriate for the age and weight of the patient.”

Siemens offers the Biograph PET/CT line that provides radiologists and pediatric patients the high-speed, high-resolution scans at lower radiation doses. Scans that took 15 minutes in older machines take 10 minutes with this tool, with the same quality, allowing for less time on the table for children. The newest models also incorporate high-definition technology to improve the resolution and contrast of images.

“From the user standpoint, the need for pediatric patients is for faster high-resolution systems,” Ghosh said. “What we have done at Siemens is develop special tech to improve image quality and cut down acquisition time, improving patient compliance and the image. We’re further developing technology to improve lesion contrast even more, in order to visualize small changes and lesions in the smaller structures of pediatric patients.”

PET in the Pediatric Future

What does the future hold for PET imaging in pediatric patients? Ideally, education efforts led by companies and individual users will increase utilization, stressing the significant advantages of PET imaging with this population. Products will continue to evolve that build on these advantages and offer even more benefits, further reducing radiation dose and increasing image quality and uses. With time, efforts to educate the medical community and greater population, and continued evolution of products, PET imaging will perhaps emerge as a highly utilized and appropriate option for children.

“PET imaging is truly unique in its powers for early diagnosis and effective disease management for pediatric patients,” Ghosh said. “When physicians accept and visualize the significant benefits of this tool, and recognize that it’s a very cost-effective investment, it will have a major impact in the long term and make a major difference in the field.”

Amy Lillard is a contributing writer for Medical Imaging. For more information, contact .