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 (r2 = 0.88). Similar results were obtained from comparisons with deparaffinized biopsies (6.6±0.3, r2=0.87) and histology (6.7±1.3, r2=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.ConclusionLIC 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.