The value of MR spectroscopy and MR elastography in assessing hepatic involvement of chronic visceral acid sphingomyelinase deficiency in adults

Hepatic involvement is one of the main visceral manifestations of Acid Sphingomyelinase Deficiency (ASMD). It can lead to liver fibrosis and liver failure in a subset of patients. Better understanding of the boundary between reversible and irreversible liver involvement is important to initiate enzyme replacement therapy at the right moment. Currently, liver enzymes and liver stiffness measured with transient elastography (TE) are used to assess liver involvement of ASMD. The aim of this study was to investigate whether magnetic resonance (MR) techniques such as MR spectroscopy (MRS) and MR elastography (MRE) are useful methods to measure liver involvement of ASMD and whether they are more useful than TE. Thirteen therapy-naïve adult ASMD patients with the chronic visceral subtype and eleven age-, sex- and body mass index-matched healthy controls were recruited. All participants underwent MRS and MRE scans and had blood drawn for the measurement of liver enzymes. For patients data of TE and biochemical plasma markers for ASMD were collected. Median fat fraction measured with MRS and median liver stiffness measured with MRE did not differ significantly between ASMD patients and healthy controls (respectively median PDFF 1.0 %, range 0.2-24.2 % for patients and median PDFF 0.7 %, range 0.2-8.4 % for healthy controls, p = 0.49 and median liver stiffness 1.2 m/s, range 0.9-1.4 m/s for patients and median liver stiffness 1.3 m/s, range 1.1-1.4 m/s for healthy controls, p = 0.86). A significant correlation was observed between liver stiffness measured with MRE and liver stiffness measured with TE (R = 0.74, p = 0.014). The MRS spectra showed no specific sphingomyelin peaks. At this moment, TE seems the best method to monitor liver stiffness for adult patients with chronic visceral ASMD.