Adrenal gland iron measurement using MRI-R2* in patients with iron overload: a feasibility Study
Sarah Keller1, Bjoern Schoennagel1, Zhiyue Jerry Wang2, Hendrick Kooijman3, Gerhard Adam1, Roland Fischer4,5, and Jin Yamamura1

1Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 2Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States, 3Philips Medical Care, Hamburg, Germany, 4Radiology, Children’s Hospital & Research Center Oakland, Oakland, CA, United States, 5Biochemistry, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

Synopsis

In recent years, hepatic, cardiac, and even pancreatic iron deposition has been studied in detail. However, the presence and incidence of iron disposition of normal-sized adrenal glands has not been adequately reported. The purpose of this study was to evaluate the levels of iron deposition in the adrenal glands in patients with iron overload.

Purpose

In recent years, hepatic, cardiac, and even pancreatic iron deposition has been studied in detail. However, the presence and incidence of iron disposition of normal-sized adrenal glands has not been adequately reported (1). The purpose of this study was to evaluate the levels of iron deposition in the adrenal glands in patients with iron overload.

Material and Methods

8 Patients (age: 16-67 y) with transfusion dependent thalassemia (TDT: n=4), sickle cell disease (SCD, n=1), transfusion dependent rare anemia (DBA, sideroblastic anemia, n=3), , and one healthy control (age: 35 y) were studied at our units for clinical liver iron (LIC by biosusceptometry), relative cardiac, pancreatic, and adrenal iron assessment (by MRI-R2*/T2*). At 3.0 T (Ingenia®, Philips AG, Eindhoven, Netherlands), a breath-hold 3D multi-slice (n = 20, 8 mm, oversampling 1.5) data acquisition was used (TR = 24.3 ms, TE = 1.2-23.05 ms, t = 20 · 1.15 ms, flip angle = 3°, bandwidth 1425 Hz/pixel). In patients with suspected severe liver iron burden (LIC > 2000 µg/gliver), an additional 3D sequence with shorter echo times was used (TE = 0.65-16.93 ms, t = 20 · 0.86 ms). In vivo liver iron concentration (LIC, dry-weight conversion factor = 6) was noninvasively measured by SQUID biomagnetic liver susceptometry (BLS). R2* was determined from a mono-exponential fit to the echo-time dependent signal amplitudes (magnitude) averaged over a whole liver slice with constant signal level offset. For iron assessment in fatty tissue (pancreas, bone marrow) by MRI-R2*, chemical shift relaxometry with effective fat shift (1.5T: 213 Hz, 3.0T: 427 Hz) and equal R2* rates for water/fat was used as described elsewhere (2).

Results

Median adrenal R2* rates and aFC for patients with iron overload differed significantly from control. Highest adrenal R2* (313.4 s-1 and 389.4s-1) was found in DBA and one ß-thalssemia patients, respectively. Most of the patients (66/69) showed increased LIC 2798 ± 1846. The mean R2* was 175 ± 127 s-1 in patients, whereas the control had an R2* of 46.1 s-1. In all patients, fatty infiltration of the adrenal gland was above the range of controls (> 14.2%), whereas the mean aFC of 24 ± 9% were found in patients with the minimum value of 13.8% and a maximum value of 36.1%, showing the fatty infiltration within the glands. Adrenal R2* correlated with LIC (rs=0.52, p=10-4) (Figure 1) and the fat infiltration correlated with adrenal R2* (rS = 0.75, p < 10-4) (Figure 2)). A side difference between the right and the left adrenal gland was not detected (Figure 3). The intra-operator variability was not different from the inter-operator variability for experienced operators (10.4 ± 10.5% vs. 11 ± 10.4%).

Conclusion

In the current study we demonstrated that MRI-R2* measurements can be adequately used for determining the relative iron distribution in the adrenal gland. Both iron and fat content in the adrenal gland could be evaluated with R2*. Besides iron accumulation, fatty degeneration might be an additional risk factor for the development of endocrinological disorder such as growth hormonal dysfunction, hypothyroidism, hypogonadism as well as adrenal insufficiency (3), and might also explain the early onset of these diseases in patients with iron overload. This hypothesis needs further investigation in asymptomatic patients.

Acknowledgements

No acknowledgement found.

References

1. Drakonaki E, Papakonstantinou O, Maris T, Vasiliadou A, Papadakis A, Gourtsoyiannis N. Adrenal glands in beta-thalassemia major: magnetic resonance (MR) imaging features and correlation with iron stores. Eur Radiol. 2005 Dec;15(12):2462-8.

2. Pfeifer CD, Schoennagel BP, Grosse R, Wang ZJ, Graessner J, Nielsen P, Adam G, Fischer R, Yamamura J. Pancreatic iron and fat assessment by MRI-R2* in patients with iron overload diseases.J Magn Reson Imaging. 2015 Jul;42(1):196-203.

3. Lahoti A, Harris YT, Speiser PW, Atsidaftos E, Lipton JM, Vlachos A. Endocrine Dysfunction in Diamond-Blackfan Anemia (DBA): A Report from the DBA Registry (DBAR). Pediatr Blood Cancer. 2015 Oct 23. doi: 10.1002/pbc.25780. [Epub ahead of print]

Figures

Figure1: Adrenal iron measured with MRI-R2*. The adrenal R2* correlated with liver iron concentration LIC (r=0.52, p=10-4).

Figure2: Adrenal fat content was calculated as aFC from the with the data sets of MRI-R2*. The adrenal fat content correlated with adrenal R2* (r = 0.75, p < 10-4).

Figure 3: Adrenal iron concentration measured with MRI-R2*. A side difference between the right and the left adrenal gland was not detected.



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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