MRI offers promise for monitoring iron overload
MRI offers promise for monitoring iron overload
Practical barriers remain for thalassemia patients
An off-label use of MRI is showing significant promise in the treatment of patients with thalassemia, a condition that often requires frequent blood transfusions which leave patients at risk for complications from a dangerous build-up of iron in the heart.
Until recently clinicians did not have a good way to measure this iron-overload, but now there is evidence that T2* measurements, which can be obtained from images taken on a standard MRI machine, can provide an appropriate guide to clinicians on the presence of iron in the heart so that they can take corrective action early.
New data on the approach was presented this year at the American Society of Hematology meeting in Atlanta. However, the approach already is being employed at about a dozen centers in the United States.
"I became interested in using MRI to diagnose iron overload in the heart because I saw several thalassemia major patients die from heart failure, and I was sure we could diagnose preclinical cardiac iron deposition by MRI," explains John Wood, MD, PhD, lead investigator of the study and a cardiologist at Children's Hospital of Los Angeles (CHLA). MRI is expensive but less expensive than liver biopsy, and it also is less expensive than heart failure, Wood says. "We've had zero admissions for cardiac disease since we started our screening program six years ago," he says. "That is a pretty good record."
Wood explains that at CHLA, clinicians follow low-risk, chronically transfused patients annually. Patients with evidence of heavy cardiac loading are evaluated every six months. "If [patients] have detectable cardiac dysfunction, we sometimes follow them every four months because they are at such high risk and are usually receiving intensive chelation," Wood says.
Early data show promise
At this year's meeting, investigators presented findings that T2* evidence of cardiac iron can be improved with administration of deferasirox, a chelating agent. In 14 of 18 patients evaluated, there was a decrease in iron with no adverse effects from the treatment. The study is being conducted at CHLA and Ospedale Regionale Microcitemie in Cagliari, Italy, using 1.5 tesla scanners, made by Chalfont St. Giles, England-based GE Healthcare. It will go on for another year. However Wood points out that he is also involved with several related research projects looking into the importance of iron in other organs as well as a four-year trial, sponsored by the National Institutes of Health, examining the pathophysiology of iron cardiomyopathy in thalassemia major patients.
While the T2* monitoring technique appears to bridge an obvious gap in treatment for thalassemia patients, there are practical barriers to large-scale implementation of the technique. For example, the images require sophisticated acquisition and processing software that is only clinically available on the newest scanners. "This is an MRI sequence and post-processing software," explains Lloyd Estkowski, development manager for GE Healthcare's MR business. "The sequence samples echos at stepping time points for the purpose of measuring T2*. The post-processing software displays the T2* values and the signal decay curve from the different sampled time points."
Further, Estkowski points out that most radiologists are not yet trained to perform and interpret this type of evaluation, and he anticipates that it will only be offered at hospital-based imaging centers. Nonetheless, the number of centers offering the evaluation is growing, according to Wood. He indicates that the response from clinicians who have used the T2* monitoring technique has been positive.
"It is much easier to adjust chelation therapy in complicated patients when you have independent assessments of the heart and liver iron," he says. "We are also able to recognize unfavorable trends in iron accumulation while there is sufficient time to make gentle, corrective interventions."
An off-label use of MRI is showing significant promise in the treatment of patients with thalassemia, a condition that often requires frequent blood transfusions which leave patients at risk for complications from a dangerous build-up of iron in the heart.Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.