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Whole brain atlas-based diffusion kurtosis imaging parameters for evaluation of minimal hepatic encephalopathy
Prateek Gupta1, Sameer Vyas1, Teddy Salan2
1Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Background And Purposes:
Minimal hepatic encephalopathy (MHE) has no recognizable clinical symptoms, but patients have cognitive and psychomotor deficits. Hyperammonemia along with neuroinflammation lead to microstructural changes in cerebral parenchyma. Changes at conventional imaging are detected usually at the overt clinical stage, but microstructural alterations by advanced magnetic resonance imaging techniques can be detected at an early stage.
Materials And Methods:
Whole brain diffusion kurtosis imaging (DKI) data acquired at 3T was analyzed to investigate microstructural parenchymal changes in 15 patients with MHE and compared with 15 age- and sex-matched controls. DKI parametric maps, namely kurtosis fractional anisotropy (kFA), mean kurtosis (MK), axial kurtosis (AK) and radial kurtosis (RK), were evaluated at 64 white matter (WM) and gray matter (GM) regions of interest (ROIs) in the whole brain and correlated with the psychometric hepatic encephalopathy score (PHES).
Results:
The MHE group showed a decrease in kFA and AK across the whole brain, whereas MK and RK decreased in WM ROIs but increased in several cortical and deep GM ROIs. These alterations were consistent with brain regions involved in cognitive function. Significant moderate to strong correlations (-0.52 to -0.66; 0.56) between RK, MK and kFA kurtosis metrics and PHES were observed.
Conclusion:
DKI parameters show extensive microstructural brain abnormalities in MHE with minor correlation between the severity of tissue damage and psychometric scores.
Insights
Diffusion kurtosis imaging reveals widespread brain abnormalities in minimal hepatic encephalopathy (MHE). These microstructural changes correlate with cognitive deficits, even before overt symptoms appear.
Area of Science:
- Neuroimaging
- Advanced MRI techniques
- Diffusion Kurtosis Imaging (DKI)
Background:
- Minimal hepatic encephalopathy (MHE) presents with subtle cognitive and psychomotor deficits despite lacking overt clinical symptoms.
- Hyperammonemia and neuroinflammation contribute to microstructural changes in the brain's parenchyma.
- Conventional imaging often misses early-stage MHE, unlike advanced MRI techniques that can detect subtle alterations.
Purpose of the Study:
- To investigate microstructural parenchymal changes in patients with MHE using Diffusion Kurtosis Imaging (DKI).
- To compare DKI-derived parameters between MHE patients and healthy controls.
- To correlate DKI findings with psychometric measures of hepatic encephalopathy.
Main Methods:
- Whole-brain DKI data acquired at 3T was analyzed in 15 MHE patients and 15 age/sex-matched controls.
- DKI parametric maps (kFA, MK, AK, RK) were evaluated across 64 white matter (WM) and gray matter (GM) regions of interest (ROIs).
- Correlations were performed between DKI metrics and the psychometric hepatic encephalopathy score (PHES).
Main Results:
- MHE patients exhibited decreased kFA and AK throughout the brain.
- MK and RK showed decreased values in WM ROIs but increased values in several cortical and deep GM ROIs.
- Significant correlations were found between RK, MK, kFA, and PHES, indicating a link between tissue damage and cognitive function.
Conclusions:
- DKI parameters demonstrate extensive microstructural brain abnormalities in MHE.
- These abnormalities are present even in the early stages of the disease.
- The correlation between tissue damage severity and psychometric scores was minor.
