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MRI-PDFF images successfully measure liver fat content

Measurement of liver fat content by MRI-derived proton density fat fraction images had an overall success rate of 96.4% in a large cohort, according to results of a prospective study.

“More and more studies have shown that incidence of fatty liver disease is increasing worldwide, fueled by the ever-growing rates of obesity,” Louise Thomas, PhD, of the University of Westminster, London, told Healio.com/Hepatology. “Identifying fatty liver disease early is essential, given it can be reversed in many people by simple lifestyle changes such as increased physical activity and calorie restriction.”

Researchers conducted the study using patient data from the UK Biobank imaging enhancement protocol that was acquired between August 2014 and October 2015. The LiverMultiScan Discover software (Perspectum Diagnostics, Oxford, U.K.) was used to create proton density fat fraction (PDFF) images from raw magnetic resonance data.

Of the 4,949 patients initially selected, 4,617 patients had their PDFF successfully calculated. The patient cohort was 53% women, had a median BMI of 26.09 kg/m² (range, 16.04-48.84 kg/m²), a median age of 62 years (range, 45-73 years) and 95.8% self-reported white ethnicity.

Factors significantly associated with higher liver fat content included sex, age, BMI, high blood pressure, weight gain and diabetes (P < 1.6 × 10^–6).

BMI showed a particularly strong association with liver fat content, as 90% of the participants who had PDFF greater than 5.5% also had a BMI greater than 25 kg/m². In comparison, patients with a BMI less than 25 kg/m² and no diagnosis of diabetes had much smaller PDFF values at a mean of 1.96%.

Women (median 1.76%) had significantly lower liver fat than men (median 2.58%), which remained so when different age groups were compared between men and women. There was no significant difference in PDFF distribution between any age group of the men, and differences decreased between the men and women the older the age group.

“MRI, and magnetic resonance spectroscopy (MRS), are now considered gold-standards for quantitative fat measurement,” the researchers wrote. “MRI methods rely on pulse sequences, where the combination of different images can give fat and water measurements. MRS is considered the most robust and quantitative of the MR-based methods. It is sensitive and shows good agreement with MRI; however, it is limited by technical demands and availability, and therefore has been applied to relatively small studies in specialist centers.”

According to the researchers, the magnetic resonance sequence takes only 3 minutes or less and requires no contrast. The high success rate on a large cohort produced a population level statistic relevant to epidemiology.

“The results of this study that we have conducted in partnership with Perspectum Diagnostics describes the high incidence of fatty liver disease in the U.K. population; this information gained from this study will be essential for identifying high risk individuals in the future,” Thomas said. “The UK Biobank will be MRI scanning 100,000 people, which provides us with a unique opportunity to look at the factors determining liver fat accumulation in relation to both lifestyle and genetic factors.” – by Talitha Bennett

Disclosure: Thomas reports she has no relevant financial disclosures. Please see the full study for the other researchers’ relevant financial disclosures.