Abstract
Purpose
We examined different approaches aimed to deal with the signal fluctuation of pancreatic T2* values due to fat infiltration in order to obtain accurate estimates of iron overload.
Methods
Pancreatic T2* values were assessed in 20 patients (13 females, 37.24 ± 9.12 years) enrolled in the Myocardial Iron Overload in Thalassemia network without and with the application of fat suppression-FS (T2*-NoFS and T2*-FS). T2* values were assessed in three different ways: (1) from the immediate fit (original T2*); (2) discarding the echoes until the achievement of a good visual concordance between the signal and the model (final_vis T2*); (3) eliminating the echoes until the achievement of a fitting error (known) <5% (final_thres T2*).
Results
For the T2*-NoFS sequence the original T2* values were significantly higher than the final_vis T2* values (difference:4.8 ± 6.1 ms; P < 0.0001) and the final_thres T2* values (difference:4.3 ± 6.1 ms; P = 0.006). For the T2*-FS sequence the original T2* values were comparable to final_vis and final_thres T2* values. The original T2*-FS values were significantly different from the original T2*-NoFS values. The final_vis T2*-FS values were comparable to the final_vis T2*-NoFS values and the final_thresh T2*-FS values were comparable to the final_thresh T2*-NoFS values. For both T2*-FS and T2*-NoFS sequences, the final_thres T2* values were not significantly different from the final_vis T2* values and no bias was present.
Conclusions
In the clinical practice, an accurate pancreatic iron overload assessment should be done by applying FS and, when needed, by discarding the TEs until the fitting error goes below 5%.
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References
Andrews PA (2000) Disorders of iron metabolism. N Engl J Med 342:1293; author reply 1294
Ozment CP, Turi JL (2009) Iron overload following red blood cell transfusion and its impact on disease severity. Biochim Biophys Acta 1790:694–701
Papakonstantinou O, Alexopoulou E, Economopoulos N, et al. (2009) Assessment of iron distribution between liver, spleen, pancreas, bone marrow, and myocardium by means of R2 relaxometry with MRI in patients with beta-thalassemia major. J Magn Reson Imaging 29:853–859
Hentze MW, Muckenthaler MU, Andrews NC (2004) Balancing acts: molecular control of mammalian iron metabolism. Cell 117:285–297
Anderson LJ, Holden S, Davis B, et al. (2001) Cardiovascular T2-star (T2*) magnetic resonance for the early diagnosis of myocardial iron overload. Eur Heart J 22:2171–2179
Pepe A, Positano V, Santarelli F, et al. (2006) Multislice multiecho T2* cardiovascular magnetic resonance for detection of the heterogeneous distribution of myocardial iron overload. J Magn Reson Imaging 23:662–668
Wood JC, Enriquez C, Ghugre N, et al. (2005) MRI R2 and R2* mapping accurately estimates hepatic iron concentration in transfusion-dependent thalassemia and sickle cell disease patients. Blood 106:1460–1465
Noetzli LJ, Papudesi J, Coates TD, Wood JC (2009) Pancreatic iron loading predicts cardiac iron loading in thalassemia major. Blood 114:4021–4026
Noetzli LJ, Coates TD, Wood JC (2011) Pancreatic iron loading in chronically transfused sickle cell disease is lower than in thalassaemia major. Br J Haematol 152:229–233
Sirlin CB, Reeder SB (2010) Magnetic resonance imaging quantification of liver iron. Magn Reson Imaging Clin N Am 18:359–381, ix
Papakonstantinou O, Foufa K, Benekos O, et al. (2012) Use of fat suppression in R(2) relaxometry with MRI for the quantification of tissue iron overload in beta-thalassemic patients. Magn Reson Imaging 30:926–933
Szczepaniak LS, Babcock EE, Schick F, et al. (1999) Measurement of intracellular triglyceride stores by H spectroscopy: validation in vivo. Am J Physiol 276:E977–E989
Wehrli FW, Ma J, Hopkins JA, Song HK (1998) Measurement of R’2 in the presence of multiple spectral components using reference spectrum deconvolution. J Magn Reson 131:61–68
Schwenzer NF, Machann J, Haap MM, et al. (2008) T2* relaxometry in liver, pancreas, and spleen in a healthy cohort of one hundred twenty-nine subjects-correlation with age, gender, and serum ferritin. Invest Radiol 43:854–860
Feng Y, He T, Gatehouse PD, et al. (2013) Improved MRI R(2) * relaxometry of iron-loaded liver with noise correction. Magn Reson Med 70:1765–1774
Positano V, Meloni A, Santarelli MF, et al. (2015) Fast generation of T2* maps in the entire range of clinical interest: application to thalassemia major patients. Comput Biol Med 56:200–210
Meloni A, Ramazzotti A, Positano V, et al. (2009) Evaluation of a web-based network for reproducible T2* MRI assessment of iron overload in thalassemia. Int J Med Inform 78:503–512
Restaino G, Meloni A, Positano V, et al. (2011) Regional and global pancreatic T*(2) MRI for iron overload assessment in a large cohort of healthy subjects: normal values and correlation with age and gender. Magn Reson Med 65:764–769
Frahm J, Haase A, Hanicke W, et al. (1985) Chemical shift selective MR imaging using a whole-body magnet. Radiology 156:441–444
Positano V, Pepe A, Santarelli MF, et al. (2007) Standardized T2* map of normal human heart in vivo to correct T2* segmental artefacts. NMR Biomed 20:578–590
de Assis RA, Ribeiro AA, Kay FU, et al. (2012) Pancreatic iron stores assessed by magnetic resonance imaging (MRI) in beta thalassemic patients. Eur J Radiol 81:1465–1470
Pepe A, Meloni A, Rossi G, et al. (2013) Cardiac complications and diabetes in thalassaemia major: a large historical multicentre study. Br J Haematol 163:520–527
O’Regan DP, Callaghan MF, Fitzpatrick J, et al. (2008) Cardiac T2* and lipid measurement at 3.0 T-initial experience. Eur Radiol 18:800–805
Ramalho M, Heredia V, de Campos RO, et al. (2012) In-phase and out-of-phase gradient-echo imaging in abdominal studies: intra-individual comparison of three different techniques. Acta Radiol 53:441–449
Anzai Y, Lufkin RB, Jabour BA, Hanafee WN (1992) Fat-suppression failure artifacts simulating pathology on frequency-selective fat-suppression MR images of the head and neck. AJNR Am J Neuroradiol 13:879–884
Positano V, Salani B, Pepe A, et al. (2009) Improved T2* assessment in liver iron overload by magnetic resonance imaging. Magn Reson Imaging 27:188–197
Tanabe K, Nishikawa K, Sano T, Sakai O, Jara H (2010) Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: a dual STIR-CHESS combination prepulse for turbo spin echo pulse sequences. J Magn Reson Imaging 31:1277–1281
Reeder SB, Pineda AR, Wen Z, et al. (2005) Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL): application with fast spin-echo imaging. Magn Reson Med 54:636–644
Yu H, Shimakawa A, McKenzie CA, et al. (2008) Multiecho water-fat separation and simultaneous R2* estimation with multifrequency fat spectrum modeling. Magn Reson Med 60:1122–1134
Acknowledgments
We thank the MIOT hematologists A. Spasiano (Napoli), B. Piraino (Messina), C. Fidone (Ragusa), M.E. Lai (Cagliari), A. Quarta (Brindisi), M. Benni (Bologna), L. Cuccia (Palermo), and C. Paci (Siena). We thank Claudia Santarlasci for skillful secretarial work and all patients for their cooperation. The MIOT project receives “no-profit support” from industrial sponsorships (Chiesi Farmaceutici S.p.A. and ApoPharma Inc.).
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The authors declare that they have no conflict of interest.
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Meloni, A., De Marchi, D., Positano, V. et al. Accurate estimate of pancreatic T2* values: how to deal with fat infiltration. Abdom Imaging 40, 3129–3136 (2015). https://doi.org/10.1007/s00261-015-0522-9
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DOI: https://doi.org/10.1007/s00261-015-0522-9