MRI shows limited diagnostic efficacy for liver iron overload

MRI may be accurate in ruling out hepatic iron overload but not accurate enough to provide a definite diagnosis, according to recent study data.

“Liver biopsy is regarded as the gold standard for assessing liver iron concentration, although it is an invasive test that potentially is associated with risk for complications,” Apostolos Tsapas, MD, PhD, MSc, from Aristotle University Thessaloniki in Greece and Harris Manchester College at University of Oxford, told Healio Gastroenterology. “Hence, existing guidelines advocate use of magnetic resonance imaging (MRI) for assessment of total body iron in patients with hereditary hemochromatosis or transfusional iron overload. Our review highlights the paucity of high-quality diagnostic accuracy to support this recommendation.”

Apostolos Tsapas

Aiming to evaluate the diagnostic accuracy of MRI for estimating liver iron overload in patients with hereditary hemochromatosis, hemoglobinopathies (sickle cell disease and thalassemia) and myelodysplastic syndrome, Tsapas and colleagues performed a systematic review and meta-analysis of studies involving 819 patients aged 3 to 79 years (mean age, 31 years). Liver biopsy analysis was used as the reference standard.

The main analysis included 17 studies with high risk of bias and substantial heterogeneity due to different MRI sequences and variable positivity thresholds. Sensitivity ranged from 0 to 1 (median, 0.94), specificity ranged from 0.5 to 1 (median, 0.89) and the diagnostic OR was 56 (95% CI, 25-127). Subgroup analyses based on MRI sequence demonstrated that T2 spin echo and T2* gradient-recalled echo MRI sequences accurately identified patients without liver iron overload (liver iron concentration >7 mg Fe/g dry liver weight), with negative likelihood ratios of 0.1 (95% CI, 0.07-0.14) for T2 spin echo sequences and 0.05 (95% CI, 0.02-0.17) for T2* gradient-recalled echo sequences. However, these MRI sequences were less accurate in definite diagnosis of liver iron overload, with positive likelihood ratios of 8.85 (95% CI, 4.91-15.93) for T2 spin echo sequences and 4.86 (95% CI, 1.74-13.58) for T2* gradient-recalled echo sequences.

“Some MRI protocols may be accurate enough to rule out iron overload, but not to definitely identify patients with this condition,” Tsapas said. “Moreover, our findings support the need for rigorous research to ascertain the effect of MRI surveillance on patient survival and development of chronic liver disease.”

Bruce R. Bacon

These findings are “surprising and a bit disappointing,” Bruce R. Bacon, MD, from the division of gastroenterology and hepatology at St. Louis University School of Medicine, wrote in an accompanying editorial. “Sarigianni et al are to be commended for a thorough systematic review. Unfortunately, the studies available are not of sufficient quality to make firm conclusions about the use of MRI to measure [hepatic iron concentration.] More studies need to be performed.”

For more information:

Bacon BR. Clin Gastroenterol Hepatol. 2015;13:64-65.

Sarigianni M. Clin Gastroenterol Hepatol. 2015;13:55-63.

Disclosure: The researchers and Bacon report no relevant financial disclosures.