 وما أوتيتم من العلم إلا قليلا 

1. بسم الله الرحمن الرحيم وما أوتيتم من العلم إلا قليلا

2. AymanEldesoky Professor of Internal Medicine Hepatogastroenterology Section Mansoura University, Egypt Presents Future Evolving Radiological Techniques of Morphological Evaluation of Liver Fibrosis

3. Liver Fibrosis and Cirrhosis • Development of non-invasive methods for evaluation of liver fibrosis is still needed and we should work harder for finding an appropriate method. • In the near future, may be with finding some appropriate non-invasive markers, we hope that we can completely obsolete the liver biopsy.

4. Modified imaging techniques Many imaging techniques with modifications are evolving for morphological evaluation of liver fibrosis: -Real-time elastography (RTE). -Tissue strain imaging. -Supersonic shear imaging (SWE). -Contrast enhanced MRI. -Diffusion-weighted MRI (DWI-MRI). -Magnetic resonance spectroscopy (MRS). -Positron Emission Tomography (PET-CT). -Single Photon Emission EomputedTomography (SPECT).

5. Real-Time Elastography • The calculation of tissue elasticity distribution is assessed in real-time ultrasound imaging and depicted as color-coded images with the conventional B-mode image in the background. The color scale includes red (soft tissue), green (intermediate, normal tissue), and blue (anelastic, hard tissue). • The diagnostic accuracy of the test is 75% for the diagnosis of significant fibrosis (F≥2).

7. Acoustic Radiation Force Impulse Elastography (ARFI) The propagation of the shear wave is followed by detection pulses that are used to measure the velocity of shear wave propagation, which is directly related to tissue stiffness: speed increases with stiffness. The results are expressed by the shear wave velocity - SWV (m/s).

9. Tissue Strain Imaging • Virtual Touch™ Tissue Imaging, the first commercially available implementation of ARFI, uses an acoustic ’push pulse’ to interrogate the mechanical strain properties or stiffness of tissue, a method similar to a physical palpation exam. • Virtual Touch Images provide complementary information to the standard B-mode image by supplying insights into changes in tissue stiffness, which are often associated with pathology.

11. Shear Wave Elastography (SWE) • It is based on supersonic shear imaging; an ultrasound-based technique used for real-time visualization of soft tissue viscoelastic properties. • In comparison with liver biopsy, serum tests and FibroScan. Sensitivity and specificity of SWE for F≥2 were 0.72 and 0.86; for F≥3 were 0.69 and 0.82 and for F=4 were 0.90 and 0.91.

13. PERFUSION-WEIGHTED MRI • Liver perfusion can be assessed by monitoring the uptake and washout of gadolinium-based contrast agents using high-temporal-resolution T1- weighted imaging. • Gadolinium-based contrast agents should be avoided in patients with severe renal dysfunction for the risk of nephrogenic systemic fibrosis. • A significant difference was reported between nonadvanced fibrosis (F0–F2) and advanced fibrosis (F3–F4).

14. DWI-MRI • DWI-MRI provides noninvasive quantification of water diffusion and micro-capillary-blood perfusion. • Sensitivity, specificity, positive predictive value, and negative predictive value were 87%, 87%, 72%, and 94%, respectively, for the diagnosis of advanced fibrosis and cirrhosis (F3-F4).

15. DWI-MR images of livers showing the mapping ADC images for patients with METAVIR scores of (A) F1 and (B) F4. In part A, the representative ROI is shown by a white circle.

16. MR Spectroscopy (MRS) • The liver is considered an ideal organ for MRS investigation due to its anatomical location and increased metabolic demands. • The role of MRS for detecting hepatic fibrosis requires further assessment in large diagnostic accuracy studies among patients with chronic hepatitis.

17. Computed tomography (CT) • CT offers improved resolution of early morphological changes with cirrhosis but has low accuracy in fibrosis detection. The severity of liver fibrosis was predicted by heterogeneous enhancement of the liver. • Perfusions changes on CT scanning is said to have the potential of discriminating between the various stages of fibrosis. However, the accuracy is yet to be proved with the gold standard.

18. Positron Emission Tomography (PET-CT) • PET-CT combines the advantages of CT with the functional ability of PET, by the fusion of PET images with CT images acquired at the same time, it helps to accurately localize the greater metabolic activity. • The use of PET-CT in the evaluation of liver fibrosis needs further validation.

19. Single Photon Emission Computed Tomography (SPECT) • Noninvasive quantification of the expression of ASGPR could help assessment of the liver function and diagnose the liver diseases. • 99mTc-MGal and 99mTc-DGal, with specific binding to ASGPR, were demonstrated as promising SPECT probes that can distinguish the fibrotic from the normal liver. • Assessment of functional hepatocytes by use of 99mTc-GSA SPECT/CT fused images is found to be useful for identifying liver fibrosis.

20. Conclusion and consensus directions

21. Conclusion and consensus directions • Ultrasound is still a widespread, low cost, user-friendly, and accurate technique for evaluation of liver fibrosis. However, it may not have a high specificity due to limitations related to the patient or operator (A1). • RTE is promising but need to performed in large number of patients with chronic hepatitis aiming to certify its advantages (B1).

22. Conclusion and consensus directions • SWE in patients with chronic hepatitis has very good accuracies for LS evaluation with the advantage that valid measurements are obtained in almost all cases, placing it as a reliable alternative of LS evaluation (A1). • Virtual Touch Tissue Quantification may prove a major breakthrough in identifying early stages of liver diseases causing cirrhosis in the near future (C2).

23. Conclusion and consensus directions • Perfusion MR imaging has the potential to enable dynamic whole-liver 3D imaging without the risks of radiation, therefore, it is likely the most promising future approach for perfusion imaging (B1). • Perfusion MR imaging requires exploration of optimal techniques for faster higher-resolution, subsequent image processing, proper estimation of tissue contrast material and validation of the existing methods of liver perfusion imaging (B1).

24. Conclusion and consensus directions • CT offers improved resolution of early morphological changes with cirrhosis but has low accuracy in fibrosis detection (B2). • The use of PET-CT in the evaluation of liver fibrosis needs further validation (C2). • The use of 99mTc-GSA SPECT/CT fused images is found to be useful for identifying liver fibrosis (B2).

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