New MRI Technique Visualizes Tumors in Children

A new MRI technique - ferumoxytol-enhanced whole-body diffusion-weighted MRI - is an effective alternative to standard PET/CT imaging for assessing cancer tumors in children, according to a study published in The Lancet Oncology.

Although imaging tests are essential for staging cancer in children, the current standard test is PET/CT, which exposes the patients to radiation. This is a concern because of the increased risk of secondary cancers later on in life, even with the low-dose protocols.

“Even with child-adapted low-dose protocols, patients undergoing a single 18F-FDG PET/CT scan are typically exposed to ionizing radiation equivalent to roughly 700 to 750 chest radiographs (10 to 20 mSv) and four times the yearly background dose from natural radiation,” lead researcher Heike Daldrup-Link, MD, said in a release.

The researchers, from Stanford University School of Medicine in California, undertook a study comparing the MRI technique, which uses the iron supplement ferumoxytol to enhance tumor visibility, with standard clinical CT plus 18F-fludeoxyglucose (18-FDG) in assessing children and young adults with malignant lymphomas and sarcomas. The ferumoxytol was being used “off-label” as a contrast agent.

Twenty-two scans of 23 patients, aged 8 to 33, performed between February 24, 2012, and October 3, 2013, were analyzed; one patient did not complete the scan. Two experienced radiologists interpreted the MR images and two nuclear medicine physicians interpreted the 18-FDG PET/CT images. The reviewers were looking at image quality based on a four-point scale, in addition to the presence or absence of tumors.

The findings:

158/174

Sensitivities

93.7 percent

90.8 percent

97.7 percent

99.5 percent

Diagnostic accuracies

97.2 percent

98.3 percent

“Tumor staging results showed very good agreement between both imaging modalities,” the authors wrote.

This new technique does not require new equipment and could be used on different MRI scanners for roughly the same cost as the PET/CT examination, they pointed out.

The researchers concluded that the ferumoxytol-enhanced whole-body diffusion-weighted MRI was an effective alternative to 18F-FDG PET/CT for staging of children and young adults with cancer, without using ionizing radiation.