Aims and objectives
Shear stiffness is an important physical property of tissues and has been found to gradually increase with increasing hepatic fibrosis in chronic liver disease [1,
2].
In magnetic resonance imaging (MRI),
it can be measured as image contrast by using magnetic resonance elastography (MRE),
a technique that has been widely used to quantitatively assess shear stiffness for a diagnostic staging of hepatic fibrosis [1,
3,
4].
MRE is a completely non-invasive imaging technique,
and the results can be easily interpreted in the clinic for molecular...
Methods and materials
This study involved 39 patients with several liver diseases and after obtaining written informed consent,
all patients underwent an MR examination including conventional MRE and diffusion-weighted image (DWI) sequence (see Table 1).
In the DWI sequence,
27 patients and 12 patients were scanned using 3 and 5 b-value,
respectively.
MR imaging
1.
MRE protocol
An external driver device (60 Hz) was used to induce shear waves in the liver tissue,
and axial imaging of the abdomen with breath-holding was performed for conventional MRE.
Imaging parameters...
Results
The results of this study are indicated in Figure 2 and 3.
The signal attenuation derived from the three b-values,
ADC0-1500 and D* against the measured shear stiffness,
showed good correlation in comparison to that from the use of five b-values.
In the fast diffusion component of three b-value,
D* resulted in good correlation while there was no correlation on the ADC0-200.
There was no correlation between the measured shear stiffness and the slow diffusion component,
the ADC200-1500,
and D.
In each of the results...
Conclusion
The purpose of this study was to investigate the effect of the IVIM model and the number of b-value on accurate calculation of the virtual MRE.
In this study,
the results of the linear regression between the estimated IVIM parameter map and the measured shear stiffness depended on IVIM models and the number of b-value.
The result suggest that the estimated IVIM parameter map not only has information about the shear stiffness obtained from non-Gaussian diffusion,
but also contains several factors which are unwanted for...
References
1.
Yin M,
Talwalkar JA,
Glaser KJ et al (2007) Assessment of hepatic fibrosis with magnetic resonance elastography.
Clin Gastroenterol Hepatol.
5:1207-1213
2.
Bell H,
Jahnsen J,
Kittang E,
Raknerud N,
Sandvik L (2004) Long-term prognosis of
patients with alcoholic liver cirrhosis: a 15-year follow-up study of 100 Norwegian patients admitted to one unit.
Scand J Gastroenterol.
39:858-63
3 Muthupillai R,
Lomas DJ,
Rossman PJ,
Greenleaf JF,
Manduca A,
Ehman RL (1995)
Magnetic resonance elastography by direct visualization of propagating acoustic
strain waves.
Science.
269:1854-7...