St. Jude researchers find that MRI can replace biopsy for monitoring iron

    Jane S. Hankins, MD, MS

    Nobody likes needles. So it’s good news that St. Jude researchers have found they can replace one big needle with a magnet. The needle is used to take a liver biopsy sample to measure the body’s iron level; and the magnet is the heart of a magnetic resonance imaging (MRI) machine.

    In a new study, St. Jude researchers show that MRI is just as accurate for measuring the body’s iron levels as analyzing a liver biopsy sample. Such iron level measurement is critical to guide treatment of iron overload. The results of the study appear in the May 14 issue of the journal Blood.

    “Iron overload happens because a patient needs repeated blood transfusions to treat such disorders as sickle cell anemia and thalassemia,” said Jane Hankins, MD, of Hematology, the study’s lead author. “This iron accumulates in critical organs, particularly the heart and liver, and it can cause failure of these organs. Since these patients cannot stop receiving blood transfusions, they are in a difficult position because they may die from the disease or the iron accumulation.”

    While iron overload can be effectively treated with chelation therapy to remove iron from the body, such treatment requires periodic testing, traditionally done by taking a biopsy, to monitor iron levels.

    “Biopsy has inherent risks because it is an invasive procedure,” Hankins said. “There may be risk of pain; and since it is invasive, there is always the possibility of complications from anesthesia and infection. The liver is a fragile organ, and there is the risk of bleeding.”

    Researchers at other institutions had discovered that it was possible to use a specially equipped MRI scanner to measure body iron levels. However, not enough studies had been done to ensure that the MRI method yielded measurements as accurate as analyzing biopsy samples.

    Therefore, in their analysis, Hankins and her colleagues compared biopsy and MRI iron level measurements in 43 St. Jude patients who had been receiving long-term transfusions for sickle cell anemia, beta-thalassemia and bone marrow failure.

    Importantly, the patients had not yet received substantial chelation therapy, so measurements of their iron levels would not be complicated by that treatment.

    Three separate reviewers analyzed the MRI measurements and were in nearly perfect agreement. The MRI measurements were in similarly high agreement with biopsy results. In addition, the St. Jude results closely agreed with those reported by other researchers using different brands of MRI instruments.

    “The two techniques compared so well that we feel confident in relying on MRI from now on, without the need for biopsy,” said Claudia Hillenbrand, PhD, of Radiological Sciences, the study’s senior author. “Because MRI is noninvasive, it can be used to monitor patients more closely, ensuring that adjustments to therapy have the desired effect.”

    The St. Jude findings hold lessons for other centers.

    “Since our findings agreed so well with those from other studies, we think our technique and results can be shared with other centers interested in using MRI,” said study co-author Beth McCarville, MD, of Radiological Sciences. “I would also recommend that centers that rely on biopsy consider installing this analytical capability in their MRI machines and begin monitoring using this technique.”

    Other authors of the paper are Ralf Loeffler, PhD, of Radiological Sciences; Matthew Smeltzer, of Biostatistics; Mihaela Onciu, MD, of Pathology and Hematology; Winfred Wang, MD, of Hematology; Russell Ware, MD, PhD, Hematology chair; and Frederic Hoffer, MD, and Chin-Shang Li, PhD, formerly of St. Jude.

    This research was supported in part by the National Heart, Lung, and Blood Institute and ALSAC.

    June 2009