The Van Beers team recently published a report on multifrequency MR elastography in patients with viral hepatitis. Hepatic MR elastography enables to visualize the stiffness of the liver during a regular clinical examination MRI scan. From this information, the amount of fibrosis can be determined. In this paper, Philippe Garteiser demonstrates that the technique can be extended to a multifrequency acquisition, where the MR elastography scan is conducted at several acoustic frequencies simultaneously. This enables to interrogate the frequency dispersion of the stiffness with little to no increase in examination duration for the patient. This novel marker seems to be influenced by liver inflammation in a way that could potentially be harnessed for diagnosing liver inflammation and fibrosis in a single examination of the patient. These findings are published in Scientific Reports.
The purpose of this study was to assess the diagnostic value of multifrequency MR elastography for grading necro-inflammation in the liver. Fifty participants with chronic hepatitis B or C were recruited for this institutional review board-approved study. Their liver was examined with multifrequency MR elastography. The storage, shear and loss moduli, and the damping ratio were measured at 56 Hz. The multifrequency wave dispersion coefficient of the shear modulus was calculated. The measurements were compared to reference markers of necro-inflammation and fibrosis with Spearman correlations and multiple regression analysis. Diagnostic accuracy was assessed. At multiple regression analysis, necro-inflammation was the only determinant of the multifrequency dispersion coefficient, whereas fibrosis was the only determinant of the storage, loss and shear moduli. The multifrequency dispersion coefficient had the largest AUC for necro-inflammatory activity A ≥ 2 [0.84 (0.71-0.93) vs. storage modulus AUC: 0.65 (0.50-0.79), p = 0.03], whereas the storage modulus had the largest AUC for fibrosis F ≥ 2 [AUC (95% confidence intervals) 0.91 (0.79-0.98)] and cirrhosis F4 [0.97 (0.88-1.00)]. The measurement of the multifrequency dispersion coefficient at three-dimensional MR elastography has the potential to grade liver necro-inflammation in patients with chronic vial hepatitis.