Radiology: 31P MR spectroscopy depicts extent of nonalcoholic fatty liver disease

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Proton-decoupled phosphorus 31 (31P) MR spectroscopy shows promise in grading of nonalcoholic fatty liver disease and may be useful in detecting treatment response in patients with nonalcoholic steatohepatitis (NASH), according to a study published in this month’s Radiology.

The study was conducted by Ksenia Sevastianova, MD, from the department of medicine, division of diabetes and colleagues from University of Helsinki and Minerva Medical Research Institute in Helsinki, Finland.

Sevastianova and colleagues found that 31P MR spectroscopy showed promise in differentiating stages of nonalcoholic fatty liver disease by detecting an increase in signal of nicotinamide adenine dinucleotide phosphate (NADPH), a marker of inflammation and fibrogenesis in the liver.

A 3.0-T clinical imager was used by the researchers to obtain proton-decoupled 31P MR spectra in the liver of 12 control subjects, 13 patients with biopsy-proved simple steatosis due to nonalcoholic fatty liver, nine patients with NASH, and nine patients with cirrhosis.

Liver fat was determined with hydrogen 1 MR spectroscopy and the content was found to be higher in patients with nonalcoholic fatty liver disease and NASH than in patients with cirrhosis or in control subjects, noted Sevastianova and colleagues.

The 31P spectra from the patients were analyzed for phosphormonoester, phosphodiester, phosphoethanolamine, phosphocholine,  glycerophosphocholine, glycerophosphoryl ethanolamine, uridine diphosphoglucose, NADPH, inorganic phosphate, phosphoenolpyruvate, and alpha-, beta- and gamma-nucleotide triphosphate levels.

Proton-decoupled 31P MR spectroscopy revealed an elevated level of NADPH in patients with NASH and those with cirrhosis and can be used as an in vivo marker metabolite with which to detect NASH, according to Sevastianova and colleagues.

NADPH may have value as an additional tool with which to define and grade liver injury, and it should be tested in further studies that include patients with liver disease not caused by nonalcoholic fatty liver disease, added Sevastianova and colleagues.

The researchers concluded that 31P MR spectroscopy could help to select patients for invasive liver biopsy and possibly replace biopsy in some patients.