Table 2.
Increases or Decreases in Liver Fat Content Were Consistent Across All Segments Between MRS and MRI-PDFF
| Total MRI-PDFF Change Between Enrollment and Week 24 (After Treatment or Placebo)
|
P Value | ||
|---|---|---|---|
| Fat Fraction Decrease ≤ 1% | Fat Fraction Increase ≥ 1% | ||
| Liver segments* | |||
| 1 | −5.2 (5.2) | 4.4 (3.6) | <0.0001 |
| 2 | −6.3 (5.4) | 5.2 (3.4) | <0.0001 |
| 3 | −6.3 (6.1) | 4.8 (3.5) | <0.0001 |
| 4a | −5.6 (5.6) | 4.7 (3.4) | <0.0001 |
| 4b | −5.7 (4.9) | 4.8 (3.8) | <0.0001 |
| 5 | −6.6 (4.8) | 5.1 (3.8) | <0.0001 |
| 6 | −6.3 (4.9) | 5.5 (3.6) | <0.0001 |
| 7 | −6.7 (4.9) | 5.3 (3.8) | <0.0001 |
| 8 | −6.6 (5.1) | 5.1 (3.4) | <0.0001 |
| MRI-PDFF average | −6.6 (4.6) | 5.8 (3.9) | <0.0001 |
| MRS† | −7.6 (5.8) | 4.9 (3.2) | <0.0001 |
| MRI level‡ | |||
| Superior | −6.2 (4.4) | 5.9 (3.4) | <0.0001 |
| Middle | −6.8 (4.6) | 5.3 (3.5) | <0.0001 |
| Inferior | −6.8 (5.0) | 5.5 (3.4) | <0.0001 |
The data are expressed as means differences with standard deviation. An independent sample t test (assuming equal variance) was performed for all continuous variables for comparisons between groups. A paired sample t test was performed for comparisons within groups. Mean differences reflect comparisons between baseline averages minus posttreatment averages.
Longitudinal changes in MRI-PDFFs measured in all nine liver segments were used to calculate average segmental and overall fat fraction changes in patients with increased fat fractions versus patients with decreased fat fractions between weeks 0 and 24. The fat content in each liver segment was calculated via the averaging of three colocalized ROIs. The MRI total average was calculated with 27 ROIs: 3 from each liver segment.
Longitudinal changes in MRS measurements from a 2 × 2 × 2 cm3 cube (voxel) within the liver at week 0 and week 24 in patients with increased fat fractions versus patients with decreased fat fractions were used as reference points.
Internal validation was performed through the colocalization of MRI-based PDFF measurements to the reference MRS voxel. Three ROIs were placed on the PDFF maps in the same locations as the spectroscopic voxel (one through the superior third of the voxel, one through the middle third of the voxel, and one through the inferior third of the voxel).