You are reporting a liver MRI, and you note that the liver is of low signal on in-phase sequences, and relatively higher signal on out-of-phase sequences. What do these appearances suggest?
Nothing - Normal Liver | |
Hepatic Steatosis | |
Haemochromatosis | |
Hepatitis | |
Wilson’s Disease |
These MRI findings are typical of Haemochromatosis. Iron deposition produces susceptibility artefact reducing signal on all MRI sequences, but especially T2 and Gradient Echo. This makes the liver look darker than skeletal muscle. In a normal liver the signal on in-phase and out-of-phase sequences is fairly equivalent. In diffuse hepatic steatosis (fatty infiltration), there is signal drop out on the out-of-phase sequences. The opposite is true for haemochromatosis, where the in-phase sequences (which are more susceprtible to T2* effects) demonstrate significant signal drop out when compared with the out-of-phase sequences.
Copper deposition in Wilson’s disease does not have a ferro-magnetic affect, and so does not cause signal drop-out. Acute hepatitis would not have this effect on these MRI sequences.
References
http://radiopaedia.org/articles/haemochromatosis
Fatty Liver: Imaging Patterns and Pitfalls: http://pubs.rsna.org/doi/full/10.1148/rg.266065004
http://pubs.rsna.org/doi/pdf/10.1148/radiographics.14.6.7855342