Endoscopic ultrasound elastography for solid pancreatic lesions

Table 1 Results of 4 large studies using pattern recognition of elastography for diagnosis of solid pancreatic lesions

Author	Giovannini et al[4], 2006		Giovannini et al[8], 2009		Janssen et al[9], 2007			Iglesias-Garcia et al[10], 2009
	Elastic score /pattern	Interpretation	Score	Inter-pretation	Type	Color	Interpretation	Pattern	Interpretation
Score and interpretation	Distortion for entire low echo area	Normal pancreas	A (elastic score 1 and 2)	Benign	Homogeneous	A = blue	B = normal pancreas	Homogeneous green	Normal pancreas
	No distortion on low echo area even for a part	Fibrosis, chronic pancreatitis						Heterogenous green	Inflammatory pancreas
	Distortion at the edge of low echo area, even for a part	Small adeno-carcinoma	B (elastic score 3)	Indeter-minate	2 or 3 colors	B = green/yellow		Homogeneous blue	Ductal pancreatic adenocarcinoma
	No distortion for entire low echo area	Endocrine tumor	C (elastic score 4 and 5)	Malignant	Heterogeneous	C = red	A/B = chronic pancreatitis and neoplasia	Heterogeneous blue	Neuroendocrine tumor
	No distortion on low echo area and surrounding	Advanced adeno-carcinoma
Sensitivity	100		92.3		65.9 (chronic pancreatitis),			100
					93.8 (neoplasia)
Specificity	67		80		56.9 (chronic pancreatitis),			85.5
					65.4 (neoplasia)
Accuracy	NA		89.2		60.2 (chronic pancreatitis), 73.5 (neoplasia)			94

NA: Not available.

Table 2 Results of studies using strain ratio of elastography for an evaluation of solid pancreatic lesions

Ref.	Diseases of comparison (n)	Reference area	Cut off point	Sensitivity	Specificity
Iglesia-Garcia et al[14]	PC (49) vs CP (27)	Soft tissue	6.04	100	96.3
	PC (49) vs PNET (6)		26.63	100	87.8
Itokawa et al[11]	PC (72), PNET (9), CP (20), normal pancreas (8)	Normal pancreas	23.66 in MFP vs 39.08 in PC
Dawwas et al[12]	Malignant (87): (PC, PNET, metastatic cancer) And benign (17) (pancreatitis)	Soft tissue	4.65	100	16.7
Kongkam et al[13]	PC (23), PNET (5), Meatastasis (1), CP (2), AIP (3), other (4)	Soft tissue	3.17	86.2	66.7
			6.04	75.9	77.8

PC: Pancreatic cancer; PNET: Pancreatic neuroendocrine tumor; CP: Chronic pancreatitis; AIP: Autoimmune pancreatitis.

Table 3 The histogram parameters[5,21,45]

Images	Parameters	Information	Interpretation
Gray scale images	Mean	Mean of the gray levels	Higher mean value indicates softer tissue
	Standard deviation	Standard deviation of the gray levels	Higher value indicating heterogeneous hardness
	ASM	Measure of the homogeneity on the gray scale image
	Contrast	Measure of local gray level variation on the gray scale image
	Correlation	Measure of gray level linear
		dependence on the gray scale image
	Entropy	Measure of the randomness of gray level distribution
	IDM	Measure of the homogeneity on the gray scale image
	Skewness	Measure of the asymmetry of the gray level distribution	Higher value indicating higher or lower hardness
	Kurtosis	Measure of the “peakedness” of the gray level distribution	Higher value indicating concentration of a specific hardness
Black and white image	% area	Percentage of the white area (= hard area)
	Mean of Complexity	Complex ratio of the shape of the white area (= hard area) and is calculated as periphery2/area of the white area