Liver Iron Susceptometry

Fischer, Roland; Farrell, D. E.

doi:10.1002/9783527610174.ch4e

Cited by 39 publications

(68 citation statements)

References 46 publications

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“…The magnetic susceptibility of a tissue is determined by the strength of the magnetic response evoked in the tissue by an applied magnetic field. 6,25 This property is much simpler than the resonance behavior that results from the application of the oscillating magnetic fields used in MRI. While in a steady applied magnetic field, all materials respond with an induced magnetic field of their own.…”

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

“…35 Priorities in basic and clinical research in the further development of biomagnetic susceptometry for the measurement of tissue iron were identified as (1) developing innovative instrumentation for biomagnetic susceptometry that is suitable for routine clinical use in studies of iron overload, such as liquid-nitrogen cooled superconducting instruments, devices using nonsuperconducting magnetometers, or means of adapting MRI instruments for measurement of magnetic susceptibility; (2) improving biomagnetic susceptometry by the development of methods to more precisely determine the susceptibility of tissue overlying the organ of interest-for example, the bone, muscle and subcutaneous tissue overlying the liver; (3) conducting additional research to develop biomagnetic susceptometry as a means of measuring tissue iron concentrations in the heart, endocrine tissue, brain, and other organs through the use of instrumentation with arrays of magnetic sensors or by examining the potential use of magnetic susceptibility tomography. 25 …”

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

“…6,26 Despite providing noninvasive, quantitative measurements of hepatic iron stores, clinical adoption of susceptometry has been limited, in part because of the cost and complexity of the instruments. At present, the only susceptometers in clinical use are at Columbia University, 6 the University of Hamburg, Germany, 25 and the University of Turin, Italy; a fourth instrument is being installed at the Children's Hospital Oakland Research Institute, California. These instruments have now been used in studies of thousands of patients with iron overload.…”

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

“…25 Superconducting materials lose all electrical resistance below a certain temperature, called the transition temperature, or T C . Until 1986, all known superconducting materials had transition temperatures near absolute zero and required a bath of liquid helium (4.2°K) to keep their temperature below T C .…”

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

See 3 more Smart Citations

Noninvasive measurement of iron: report of an NIDDK workshop

Brittenham

Badman

2003

Blood

255

188

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Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

Section: Detection Of Iron Overload By Magnetic Susceptometrymentioning

confidence: 99%

See 2 more Smart Citations

Noninvasive measurement of iron: report of an NIDDK workshop

Brittenham

Badman

2003

Blood

255

188

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“…3 However, this value cannot be found in that citation nor can it be derived from any given data elsewhere. 4 Most likely, the regression coefficient of 0.46 (functional relationship between LIC from BLS and biopsy) was mistaken for a correlation coefficient R.…”

Section: Italian Society Of Hematology Guidelines For Thalassemia Andmentioning

confidence: 99%

Italian Society of Hematology guidelines for thalassemia and non-invasive iron measurements

Nielsen¹,

Engelhardt²,

Grosse³

et al. 2008

Haematologica

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© F e r r a t a S t o r t i F o u n d a t i o n Italian Society of Hematology guidelines for thalassemia and non-invasive iron measurements: Author replyWe greatly appreciated the comments of Dr Nielsen and colleagues on the guidelines for the management of iron overload in thalassemia we produced on behalf of the Italian Society of Hematology.1 Dr Nielsen and colleagues are concerned about our interpretation of data regarding the accuracy of biomagnetic liver susceptometry (BLS) as a non-invasive method for assessing liver iron concentration. By analyzing the existing evidence, we relied on the only two references dealing with a correlation between BLS and liver iron concentration by biopsy in patients with thalassemia. Our conclusion on the inaccuracy of BLS was mainly grounded on a paper published as an abstract by Piga et al.2 in which the sentence "on average, the LIC data obtained from BLS and biopsy were related by a factor of 0.46" was interpreted as 0.46 being the correlation coefficient of the two measurements. Thus, from this factor, we derived a R 2 of 0.21. We also relied on the conclusion of the abstract that states "overall, LIC from biopsy was generally larger than that obtained from BLS".Regarding the use of SQUID/BLS after the first study published by Gary Brittenham in 1982, 3 no other published study has confirmed the capability of SQUID to predict hepatic iron concentration with adequate methods. Any validation study of a new diagnostic quantitative procedure must compare the new methodology with a reference gold standard. Particularly a determination coefficient (R 2 ) with a prediction interval (95% CI) should be reported.Above all in this specific case the 95% prediction interval would be reasonably narrow not extending over the identified threshold for iron concentration tissue damage and death risk.4 In the setting of iron overload, the reference standard is the validated biochemical determination of hepatic iron concentration on adequate, non cirrhotic, liver biopsy specimens.5 We are not aware of any such study with results similar to that reported by Dr Brittenham with a similar 95% confidence prediction interval. Studies comparing SQUID/BLS with other technologies are of minor relevance. Moreover the cited debate on dry weight-wet weight relationship developed after an industry sponsored trial, 2 which, although important for future development, raises concern for the thousands of determinations performed for clinical practice before 2006.In conclusion, although SQUID/BLS is a highly scientific methodology, because of the limited availability, the limited literature in peer reviewed journals, the reported difficulties, and the availability of other non-invasive methods (MRI-R2) it appears rational to recommend its utilization only inside clinical trials. © F e r r a t a S t o r t i F o u n d a t i o n

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Assessment of iron stores in children with transfusion siderosis by biomagnetic liver susceptometry

et al. 1999

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To investigate the applicability of noninvasive Superconducting Quantum Interference Device (SQUID) biomagnetic liver susceptometry and its limitations in thalassemic children , 23 patients with-thalassemia major and other iron loading anemias (age: 4-16 years) and 16 age-related normal children were studied. Liver iron concentrations ranged from 600 to 11,000 µg/g liver for thalassemic patients and from 60 to 340 µg/g liver for normal patients. Measuring the respective organ volumes by sonography, liver and spleen iron stores, accounting for 80% of total body iron stores, were estimated. Nonliver contributions from the lung or intestine to the measured SQUID signals in the small-sized patients were not observed. Moreover, livers in thalassemia were found to be enlarged by 18% per 1,000 µg/g (r = 0.75, P < 10 −3). Serum ferritin values correlate significantly with iron stores (r = 0.64, P < 10 −3), but predict iron stores only within large error intervals of 4,000 µg/g liver. Analyzing the experimental data from biomagnetometry and from related transfusion and chelation treatment data within the framework of a two-compartment model, we were able to derive additional information on total body iron elimination and chelation therapy efficacy. The exponential decline of iron stores allows forecast of steady-state conditions of the final iron load for a particular transfusion and chelation therapy regi-men. Am. J. Hematol. 60:289-299, 1999.

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Liver Iron Susceptometry

Cited by 39 publications

References 46 publications

Noninvasive measurement of iron: report of an NIDDK workshop

Noninvasive measurement of iron: report of an NIDDK workshop

Italian Society of Hematology guidelines for thalassemia and non-invasive iron measurements

Assessment of iron stores in children with transfusion siderosis by biomagnetic liver susceptometry

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