Liver elastography, comments on EFSUMB elastography guidelines 2013

Table 1 Examples of studies

	Title	Comment	Ref.
Univariate approach
	Elastographic assessment of liver fibrosis in children: A prospective single center experience	Pearson’s correlation	[21]
	Is it better to use two elastographic methods for liver fibrosis assessment?	Spearman rank correlation	[22]
	Is ARFI elastography reliable for predicting fibrosis severity in chronic HCV hepatitis?	Spearman rank correlation	[23]
	Factors that influence the correlation of acoustic radiation force impulse, elastography with liver fibrosis	Spearman rank correlation	[24]
	Liver stiffness measurement using acoustic radiation force impulse elastography and effect of necroinflammation	Pearson product-moment correlation	[25]
Multivariate approach
	Liver stiffness measurements in patients with different stages of non-alcoholic fatty liver disease: Diagnostic performance and clinicopathological correlation	Spearman’s correlation (no attention paid to Bonferroni or alpha correction)	[26]
		6 factors (higher age, serum albumin, serum AST, serum cholesterol, diabetes mellitus, LSM), LSM is the only independent predictor of advanced fibrosis (odds ratio = 1.47, 95%CI: 1.23-1.77, P < 0.001)
	Assessment of liver fibrosis using transient elastography in patients with alcoholic liver disease	Spearman’s correlation (with Bonferroni test). In multivariate analysis including fibrosis, HAH, and steatosis, fibrosis was the only histological parameter significantly correlated with LSM	[27]
	FibroScan and ultrasonography in the prediction of hepatic fibrosis in patients with chronic viral hepatitis	Pearson correlation (no attention paid to Bonferroni or alpha correction)	[28]
		12 factors. Multivariate analysis showed that LSM positively correlates with hepatic fibrosis, necro-inflammatory activity and ultrasound scores
	Performance of unidimensional transient elastography in staging non-alcoholic steatohepatitis	Spearman’s correlation (no attention paid to Bonferroni or alpha correction)	[29]
		4 factors (fibrosis, ballooning, Lobular inflammation, steatosis). Multivariate analysis found fibrosis as the only factor influencing independently liver stiffness in NASH patients

LSM: Liver stiffness measurement; HAH: Hepatic abscess of hydatid origin; AST: Aspartate aminotransferase; NASH: Non-alcoholic steatohepatitis.

Table 2 Mean shear wave velocities (VirtualTouch values) of the left and right liver lobes (mean ± SD)

Ref.	n	Subjects	Left lobe (m/s)	Right lobe (m/s)
Karlas et al[158]	50	Healthy individuals	1.28 ± 0.19	1.15 ± 0.17
Karlas et al[158]	23	Patients with F1, F2 fibrosis	2.1 ± 0.73	1.75 ± 0.89
Toshima et al[159]	103	24 healthy volunteers, 79 patients with chronic liver disease	1.90 ± 0.68	1.61 ± 0.51
Piscaglia et al[157]	14	Healthy individuals	1.29 (1.00-1.60)	1.15 (0.80-1.74)
Piscaglia et al[157]	114	Patients with chronic liver disease	1.79 (0.80-4.00)	1.67 (0.45-3.76)

Table 3 Advantages and disadvantages of non-invasive methods to evaluate liver fibrosis

Parameters	Transient elastography	ARFI	2D-SWE	MR Elastography	Serum biomarkers
Advantages	High and rapid performance	High and rapid performance	High and rapid performance	High performance (applicability)	Availability
	Reproducibility	Reproducibility	Reproducibility	Reproducibility	Reproducibility
	Easy to learn	Easy to learn	Easy to learn, large ROI	Examination of the whole liver	Low cost
		Combined with conventional ultrasound	Combined with conventional ultrasound	Combined with conventional MRI
		Obesity and ascites are not limiting	Ascites are not limiting	obesity and ascites are not limiting
Disadvantages	Technical requirements (equipment) without additional use	Technical requirements (ultrasound equipment)	Technical requirements (ultrasound equipment)	Technical requirements (MRI equipment)	Non-specific (hyperbilirubinemia, hemolysis, inflammation, others)
	Intermediate cost	Intermediate cost	Intermediate cost	Extremely high cost, time consuming	Relatively high cost, limited availability (patent)
	Limited recognition of intermediate stages of fibrosis	Limited recognition of intermediate stages of fibrosis	Limited recognition of intermediate stages of fibrosis	Limited recognition of intermediate stages of fibrosis	Limited recognition of intermediate stages of fibrosis
	Blind selection of region of interest			Not applicable in case of iron deposition	Results not immediately available
	Restricted value in obese patients and ascites	Narrow range of values, small ROI
	False positive values in patients with acute hepatitis, cholestasis, and heart failure	Quality criteria not well defined	Quality criteria not well defined

ARFI: Acoustic radiation force impulse; SWE: Shear wave elastography; ROI: Region of interest; MRI: Magnetic resonance imaging.

Table 4 Performance of acoustic radiation force impulse in the identification of malignant focal liver lesions

No. of FLL	Rate of malignancy	Reference standard	Lesion types	ARFI cut-off (m/s)	QUADAS score	Ref.
105	64.8%	Biopsy, imaging	Haemangioma,FNH, focal fatty sparing, focal fat deposits adenomas, HCC, metastasis	2.7	11	[182]
60	71.7%	Biopsy, CT/MRI	haemangioma, HCC, CCC, metastasis	2	10	[183]
128	53.1%	Biopsy, surgery, imaging	Haemangioma, FNH, focal fatty change, abscess, adenoma, solitary necrotic nodule, HCC, metastasis, CCC	2.2	10	[184]
42	64.3%	Biopsy	Haemangioma, lymphoma, FNH, sarcoid, abscess, focal fatty sparing, HCC, metastasis	2.5	12	[185]
45	22.2%	Biopsy, CT/MRI	Haemangioma, metastasis	2.5	8	[186]

QUADAS: Quality assessment of diagnostic accuracy studies; HCC: Hepatocellular carcinoma; FNH: Focal nodular hyperplasia; CCC: Cholangiocarcinomas; FLL: Focal liver lesions; CT: Computed tomography; MRI: Magnetic resonance imaging.