Liver fat volume fraction quantification in patients with chronic liver diseases with separated estimation of fat and water relaxation times at 1.5 and 3.0T
Résumé
Purpose: To validate a magnitude-based method, transposable on any imaging system and for all current clinical fields (1.5 and 3.0 T) for liver fat volume fraction (FVF) quantification without dominant component ambiguity problems. Methods and Materials: MR imaging was performed at 1.5 and 3.0 T using a multiple-angle multiple-gradient echo acquisition. A quantification algorithm cor- recting for relaxation time effects using a disjointed estimation of T1 and T2* of fat and water and accounting for the NMR spectrum of fat was developed. Validations were performed in a prospective comparative study with histology on 28 patients with chronic liver diseases. Results: MR-estimated FVF and histological results were strongly correlated (ρ=0.96). ROC analysis showed that FVF allowed the diagnosis of a mild (cut-off= 5.5%) and a moderate steatosis (cut-off=15.2%) with a sensitivity/specificity of 100%. Water relaxation times (T1 and T2*) were found significantly reduced in patients with iron deposition (p < 0.01), whereas water T1 was found significantly increased in patients with cirrhosis (p < 0.01). Conclusion: This method that can be performed at 1.5 and 3.0 T on all imaging systems provide an accurate quantification of the FVF in patients with chronic liver disease. FVF could be a relevant biomarker for the clinical follow-up of patients with NAFLD as well as to quantify steatosis in the full spectrum of chronic liver diseases. Interestingly, thanks to the separated estimation of fat and water relaxation times, detection of cofactors such as iron deposition or cirrhosis in patients with NAFLD could be achieved