Liver Iron Concentration Assessed by SQUID Biosusceptometry Compared to Heat-dried Liver Biopsy: A Blinded Study.

Objective: Biomagnetic liver susceptometry (BLS) is a noninvasive method to quantify liver iron concentration (LIC). Here we report our findings from a prospective study which validates in vivo LIC from a SQUID biosusceptometer by in vitro LIC in fresh tissue and paraffin-embedded biopsies from patients at risk for iron overload. Materials: and Methods LIC was measured by BLS and biopsy. LIC by biopsy were measured in 40 dry weight fresh tissue and paraffin-embedded liver biopsy samples. LIC from biopsies and total iron scores from histology were compared to biosusceptometry. In addition, the wet-to-dry weight ratio was determined. Results: Liver iron concentrations measured by BLS and in 40 fresh tissue biopsies were related by a factor of 6.0 ± 0.2 (r 2 = 0.88). Similar results were obtained from comparisons with deparaffinized biopsies (6.6±0.3, r 2 =0.87) and histology (6.7±1.3, r 2 =0.47). In contrast, a mean wet-to-dry weight ratio of 4.1 ± 0.7 was achieved from biopsies immediately weighed after the biopsy procedure. Conclusion: LIC derived from two independent measures, the historical biopsy gold standard and biosusceptometry, were highly correlated. When comparing biosusceptometry with wet weight biopsies, the liver tissue sample size is critical.