Massive Iron Deposit Assessment

St. Jude Children's Research Hospital142 enrolled

Overview

Iron overload is a severe complication of multiple blood transfusions. As the body has no physiologic mechanism for clearing iron, repeated transfusions cause iron accumulation in organs and lead to iron toxicity. Accurate assessment of iron overload is paramount to quantify excessive iron accumulation and to monitor response to iron chelation therapy. Magnetic resonance imaging (MRI) methods have been used to noninvasively measure hepatic iron concentration (HIC). Although MRI-based measurements of transverse relaxation rates (R2 and R2\*) accurately predict biopsy-proven HICs below 15 mg Fe/g, previous studies have shown that their precision is limited for HICs above 15 mg Fe/g and inaccurate above 25 mg Fe/g. Current R2\* gradient-echo (GRE) MR techniques fail occasionally for very high iron overloads (HIC \~ 15-25 mg Fe/g) and always for massive iron overloads (HIC \> 25 mg Fe/g) because R2\* is so high that the MR signal decays before it can be measured accurately. Overall accrual: 200 patients Purpose: To determine if a new MRI (UTE) can measure the amount of iron in the liver of people with large amounts of iron and compare the results with the same patient's liver bx. Estimated patient accrual is 150. It is estimated that 41 of these patients will have clinical indication for liver biopsy.

The MIDAS study is a prospective and non-therapeutic study that will test a new MRI technique for the assessment of iron overload in the liver: the newly developed ultra short echo time (UTE), R2\*-UTE. The R2\*-UTE technique, developed by St. Jude investigators from the Department of Radiological Sciences, will be first tested in healthy volunteers for feasibility and implementation of the technique. The technique will then be tested in research participants, who will have both the R2\*-GRE and the R2\*-UTE techniques performed, in addition to a liver biopsy for liver iron quantitation if clinically indicated. Quantitation of liver tissue iron will be done at Mayo Clinic Laboratory in Rochester, Minnesota. Primary Objective: * To test the association of hepatic iron content (HIC) measured with the newly developed 1.5T R2\*-UTE technique and HIC quantified by liver biopsy in subjects with iron overload. Secondary Objectives: * To explore the relationship between 1.5T R2\*-UTE and 1.5T R2\*-GRE measurements in subjects with iron overload. * To explore the relationship between 1.5T R2\*-UTE measurements with iron studies (serum iron and transferrin saturation) in subjects with iron.

Study Type

INTERVENTIONAL

Interventions

R2*-UTEDEVICE

Ultra short echo time (UTE) magnetic resonance imaging (MRI). Study participants will undergo an MRI examination of the liver on a 1.5T MRI and a 3T MRI scanner each. Because liver biopsy metal needle fragments could interfere with the MRI measurements, the MRI exams will always precede liver biopsy. Multi-echo GRE sequences will be used to acquire images with increasing TEs. Images of the liver will be obtained in transversal slice orientation through the center of the liver at the level of the origin of the main portal vein. At equivalent slice locations R2\*-UTE scans will be performed.

R2*-GREDEVICE

Gradient-echo (GRE) magnetic resonance imaging (MRI). Study participants will undergo an MRI examination of the liver on a 1.5T MRI and a 3T MRI scanner each. Because liver biopsy metal needle fragments could interfere with the MRI measurements, the MRI exams will always precede liver biopsy. Multi-echo GRE sequences will be used to acquire images with increasing TEs. Images of the liver will be obtained in transversal slice orientation through the center of the liver at the level of the origin of the main portal vein. At equivalent slice locations R2\*-UTE scans will be performed.

Liver biopsyPROCEDURE

Indications for liver biopsy include, but are not limited, to the need to quantify liver tissue iron and the need to obtain histopathological information of the liver tissue. Liver biopsies will only be performed if clinically indicated and will be done only once per patient. The technique to be used is coaxial percutaneous (transcapsular) technique; however, a coaxial transjugular technique may be performed in subjects with increased bleeding diathesis, since it is associated with less hemorrhagic risk. Healthy volunteers will not undergo liver biopsy.

Outcomes

Primary Outcomes

Hepatic Iron Content in the Liver Using Liver Biopsy

Hepatic iron content in the liver using liver biopsy

Time frame: up to 30 days after MRI

MRI-derived R2* Values Using 1.5T UTE Technique

Hepatic iron content of the liver using MRI-derived 1.5T R2\*-UTE measurement, with results in Hz. R2\* is a measure obtained with MRI, i.e., MRI R2\*. It is measured in hertz (Hz). In lay terms, the MRI machine picks up a signal back from the tissue during the process of scanning the tissues. With every "picture taken", this signal is strong in the beginning and then wanes off. R2\* reflects how fast the signal wanes off. If there is too much iron in the tissue, the signal disappears faster, making the T2\* value low. T2\* is the reciprocal of R2\* (R2\*= 1/T2\*). So, if the signal drops fast, the T2\* is low and the R2\* is high. In this study, we are measuring the R2\* value. The higher the R2\*, the more iron in the liver tissue. We can compare the R2\* value with that of a liver biopsy to then use the R2\* value to tell us how much iron is in the liver without having to biopsy the liver.