Published online Sep 7, 2020. doi: 10.3748/wjg.v26.i33.4996
Peer-review started: May 29, 2020
First decision: June 12, 2020
Revised: June 14, 2020
Accepted: August 1, 2020
Article in press: August 1, 2020
Published online: September 7, 2020
Cholelithiasis is one of the most common and substantial health problems of the digestive system worldwide. Liver biopsy is the gold standard for evaluating liver fat accumulation, however, biopsy is an invasive procedure limited by sampling bias and variability among observers and intra-observers. Computed tomography (CT) and ultrasonography have been previously used to detect liver steatosis. However, both CT and ultrasonography have limited accuracy. Advanced magnetic resonance spectroscopy (MRS) has been shown to be a robust method for quantifying liver fat and iron accumulation. Whether liver fat and iron content as assessed by multi-echo MRS are predictive of cholelithiasis remains to be determined.
The increase in total cholesterol synthesis can cause tissues to be overloaded with fatty acids, resulting in more lithogenic bile due to overproduction of hepatic cholesterol. The multi-echo single-voxel stimulated echo acquisition mode (STEAM) spectroscopy sequence minimizes the influence of T1 relaxation and corrects the T2 effect of different echo times, and can achieve satisfactory quantification of liver fat and iron, which may be helpful to diagnosis mild liver steatosis in patients with cholelithiasis.
To investigate whether liver fat accumulation measured by high-speed T2-corrected multi-echo MRS is a risk factor for cholelithiasis. The findings obtained can provide information for predicting the risk of cholelithiasis by using MRS.
This study retrospectively enrolled 40 patients with cholelithiasis (mean age: 54.8 ± 14.6 years) and 31 healthy controls (mean age: 50.6 ± 14.3 years) who underwent high-speed T2-corrected multi-echo single-voxel MRS. Magnetic resonance imaging was performed on a 3T MR scanner (MAGNETOM Skyra; Siemens Healthcare, Erlangen, Germany). The proton density fat fraction (PDFF), R2 value, and waist circumference (WC) were calculated. Spearman’s correlation analysis was used to analyze the relationship between PDFF, R2 and WC values. Significant predictors of the risk of cholelithiasis were determined by multivariate logistic regression analysis. Receiver operating characteristic curve analysis was used to evaluate the discriminative performance of significant predictors.
Patients with cholelithiasis had higher PDFF (5.8% ± 4.2% vs 3.3% ± 2.4%, P = 0.001), R2 value (50.4 ± 24.8/s vs 38.3 ± 8.8/s, P = 0.034), and WC value (85.3 ± 9.0 cm vs 81.0 ± 6.9 cm, P = 0.030) compared with healthy controls. PDFF was positively correlated with WC (r = 0.502, P < 0.001) and R2 (r = 0.425, P < 0.001). Only PDFF was an independent risk factor for cholelithiasis (P = 0.003, OR: 1.79, 95%CI: 1.22-2.62), and the area under the curve of PDFF was 0.723 for discriminating cholelithiasis from healthy controls at the cut-off value of PDFF was 4.4%. However, due to the relatively small sample size, a large population from multiple centers is needed for further validation of our findings.
PDFF measured by high speed T2-corrected multi-echo MRS is associated with cholelithiasis. MRS can be used as a quantitative tool to simultaneously monitor the liver fat content and hepatic iron overload.
This study describes that PDFF derived from high speed T2-corrected multi-echo MRS can predict the risk of cholelithiasis. MRS can quantitatively detect liver steatosis in a simple breath-hold of 15s, which holds a good potential for clinical application.