1. QUANTITATIVE IMAGING OF HUMAN LIVER IRON CONCENTRATIONS IN VIVO
Tim St Pierre1, A Fleming1, W Chua-anusorn1, P Clark1,
E Rossi, G Jeffrey2,3, J Olynyk2
The vision we will be presenting to you today is the development of an internet service industry for the assessment of iron overload by MRI, which has emerged as an exciting possibility from our research into body-iron overload, and from our development of a novel imaging methodology which enables the generation of [Fe] maps.
And we will outline a time-frame over which this could be developed into a multi-million dollar service industry.

2. Declaration of competing interests
Three of the investigators on this project are involved with a commercial venture based on non-invasive measurement of liver iron concentrations
Tim St Pierre
Paul Clark
Wanida Chua-anusorn

3. Standard methods of assessing the body iron burden
Ferritin serum assay
Needle biopsy of the liver
So let’s look at the ...

4. Liver biopsy

5. Non-invasive measurement of liver iron concentration

6. The magnetic resonance imager (MRI)

7. A liver full of magnets!

8. Proton transverse relaxation rate (R2) image and distribution…
You can see the map here, which has been superimposed on one of the five T2-weighted images acquired for the calculations.
Now, the power of this development lies not only in the ability to see the heterogeneity of iron loading throughout the liver, the degree of which can be parameterised by the width of the Gaussian distribution of the relaxivity values, but by the position of the peak, which quantifies the mean level of iron loading in the liver.
If we go to the next slide …
Clark et al, Mag Res Imaging 18 (2000)

9. Liver R2 images and distributions
healthy volunteer
3 iron loaded subjects with sequentially increasing liver iron concentrations

10. R2 image analysis of human liver samples
Iron loaded liver tissue: dissection outline

11. R2 image analysis of human liver samples
Clark et al, Magn Reson Med 49 (2003)

12. R2 image analysis of human liver samples
Clark et al, Magn Reson Med 49 (2003)
Mean R2 vs iron concentration for 32 cubes of liver dissected from a single iron loaded liver post mortem.

13. Measurement of liver R2 in vivo
Needle biopsy samples a
few milligrams of tissue from
the right hand side of the liver

14. Relationship between <R2> in right hand side of liver
and needle biopsy iron concentration (dry wt)
St Pierre et al (2005) Blood 105,

15. Sensitivity and specificity of R2-LIC measurements to biopsy LIC measurement
LIC Threshold
mg Fe/g dry
Clinical Relevance
Sensitivity
Specificity
1.8
Upper 95% of normal
94%
(86-97)
100%
(88-100)
3.2
Suggested lower limit of optimal range for liver iron concentrations for chelation therapy in transfusional Fe overload *
(85-98)
(91-100)
7.0
Suggested upper limit of optimal range for liver iron concentrations for transfusional Fe overload and threshold for increased risk of iron induced complications *
89%
(79-95)
96%
(86-99)
15.0
Threshold for greatly increased risk for cardiac disease and early death in patients with transfusional iron overload *
85%
(70-94)
92%
(83-96)
* Olivieri NF, Brittenham GM. Blood. 1997; 89:

16. Measurement of R2 standards

17. Measurement of R2 standards
St Pierre et al (2005) Blood 105,
R2 vs paramagnetic Mn2+ concentration for the same series of phantoms measured on 13 different 1.5T MRI scanners

18. Reproducibility of liver R2 measurements
on 2 MR scanners
Random error: 7.7%
Systematic error: 1.2%
St Pierre et al, NMR in Biomed 2004; 17,

19. Assessment of liver damage risk from iron loading

20. Using age and LIC at diagnosis to predict fibrosis grade in HH
Olynyk et al (2005) Am. J. Gastroenterol 100, 837

21. Using age and LIC at diagnosis to predict fibrosis grade in HH
Olynyk et al (2005) Am. J. Gastroenterol 100, 837

22. Relationship of R2 distribution with liver histology
250 mm
Perl’s Stain
250 mm
Reticulin Stain
Clark et al, Magn Reson Med 49, (2003)

23. Relationship of R2 distribution with liver histology
250 mm
Perl’s Stain
250 mm
Reticulin Stain
Clark et al, Magn Reson Med 49, (2003)

24. Relationship of R2 distribution with liver histology
250 mm
Perl’s Stain
250 mm
Reticulin Stain
Clark et al, Magn Reson Med 49, (2003)

25. R2 distribution and liver biopsy histology
Non-cirrhosis
LIC = 10.2 mg/g DW
R2 = 99 ± 20
Cirrhosis
LIC = 12.6 mg/g DW
R2 = 132 ± 50

26. R2 distribution and liver biopsy histology
Mild Fibrosis
LIC = 1.1 mg/g DW
R2 = 30.9 ± 7.4
The possibility also exists that R2-MRI may be developed to identify cirrhosis in patients with normal levels of liver iron.
Note that the HIC is in the normal range.
Cirrhosis
LIC = 1.8 mg/g DW
R2 = 29.9 ± 13.4

27. Relationship between LIC and total body iron stores in hereditary hemochromatosis

28. Serum ferritin and body iron stores in hereditary hemochromatosis
Olynyk et al (1998) Am. J. Gastroenterol. 93, 346

29. LIC by biopsy vs total body iron stores by quantitative venesection
Hereditary Hemochromatosis
Thalassemia
Angelucci et al (2000) N Eng J Med 343, 327
Summers et al (1990) Hepatology 12, 20
Olynyk et al (1998) Am. J. Gastroenterol. 93, 346

30. Body iron store distribution
Liver iron store
Extrahepatic iron store
Liver volume V
Total body iron store = liver iron store + extrahepatic iron store
Liver iron store = liver iron concentration x liver volume

31. Measuring total body iron stores (TBIS) and liver iron stores
Measure LIC 3 times during venesection
Measure liver volume
Weighted fit through data
Extrapolate LIC to zero to obtain TBIS
Extrapolate LIC to 1 mg Fe/g dw for comparison of TBIS with other studies

32. Subjects & methods
Newly diagnosed hereditary hemochromatosis subjects were recruited (n=19) (male = 12, female = 7)
17 C282Y homozygotes, 1 C282Y/H63D, 1 Wild-type/H63D
LIC measured with R2-MRI [6]
Liver volume measured with MRI simultaneously
Subjects recalled for follow-up LIC measurements at estimated half way point in venesection schedule and near end of schedule

33. Non-invasive monitoring of LIC during venesection
Subject 1
Subject 2
Subject 3
Subject 4
LIC measured using R2-MRI. Dashed line is upper limit normal
Subject 5
Subject 6
Subject 7
Solid lines are weighted fits to the data yielding estimate for initial LIC and total body iron store (from mL of blood to reach zero LIC).

34. LIC vs TBIS by quantitative venesection in HH
Biopsy Measurements
R2-MRI Measurements
Summers et al (1990) Hepatology 12, 20
Olynyk et al (1998) Am. J. Gastroenterol. 93, 346
1.65
1.09
Gradients

35. LIC vs TBIS by quantitative venesection
Biopsy Measurements
(thalassemia)
R2-MRI Measurements
(hereditary hemochromatosis)
Angelucci et al (2000) N Eng J Med 343, 327

36. LIC vs TBIS by quantitative venesection
Biopsy Measurements
(thalassemia)
R2-MRI Measurements
(hereditary hemochromatosis)
Gradient
7.3
10.6
Angelucci et al (2000) N Eng J Med 343, 327

37. Body iron store distribution
Liver iron store
Extrahepatic iron store
Liver volume V
Total body iron store = liver iron store + extrahepatic iron store
Liver iron store = liver iron concentration x liver volume

38. a is fraction of total body iron store in the liver
Liver iron store
Extrahepatic iron store
Liver volume V
Total body iron store = liver iron store / a

39. Fraction (a) of iron store in liver
Mean fraction of iron stores in liver is 45%
Range %

40. New model for iron distribution in HH
Assume fraction,  , of total body iron store in the liver varies linearly with rate of liver iron loading (LIC/Age)  0
LIC / Age
Gradient = 

41. New model for predicting iron stores in HH
95% limits of agreement
New Model: ± 40%
Using LIC: ± 72%
Using Ftn: ± 102%

42. Summary (1)
R2 imaging ……
can be used to measure non-invasively liver iron concentrations (LIC) with known accuracy and precision
has good sensitivity and specificity for measurement of LIC at both low and high LIC ranges
has dynamic range of measurement from normal LIC to the very highest concentrations encountered in clinical practice
works on most 1.5 T MRI units
has health regulatory authority clearance for LIC measurement in USA (FDA), Europe (CE Mark), and Australia (TGA)
may have the potential to detect liver cirrhosis/fibrosis

43. Summary (2) Non-invasive measurement of LIC ……
Enables serial monitoring of patients on blood transfusion and chelation therapy to aid in chelation dose determination
Aids in the identification of newly diagnosed hemochromatosis patients who are at risk of iron induced liver damage

44. Summary (3) Non-invasive measurement of LIC and liver volume…
Has demonstrated a correlation between fraction of TBIS in the liver and rate of iron loading in HH
Enables a more accurate prediction of venesection requirements for HH subjects compared with LIC or serum ferritin measurements

45. Co-workers School of Physics, University of Western Australia
Paul Clark
Wanida Chua-anusorn
Adam Fleming
School of Medicine, University of Western Australia
Gary Jeffrey
John Olynyk
Ric Rossi
Thalassemia Research Center, Mahidol University
Pensri Pootrakul
Department of Haematology, Prince of Wales Hospital
Rob Lindeman
SKG Radiology
Erin Robins