Table 1.

Characteristic of case-control studies included in the study

Author	Year	Country	Language	Ethnicity	Sample size		Gender (M/F)	Age (years)	Instrument	Contrast-agent	2×2 table				QUADAS score
					Malignant	Benign					TP	FP	TN	FN
Jiang T [11]	2013	China	Chinese	Asian	31	64	4/38	45	Mylab	SonoVue	28	5	3	59	22
Li M [12]	2011	China	Chinese	Asian	34	48	27/55	42	Siemens	SonoVue	31	3	3	45	21
Lin SB [13]	2012	China	Chinese	Asian	68	96	54/110	42	Siemens	SonoVue	62	6	6	90	21
Zhang HL [14]	2013	China	Chinese	Asian	12	85	14/83	51.2	Siemens	SonoVue	11	2	1	83	23
Chen LB [15]	2013	China	Chinese	Asian	47	53	8/34	50.3	Siemens	SonoVue	43	15	4	38	22
Xu YB [16]	2013	China	Chinese	Asian	59	33	27/65	45.4	Siemens	SonoVue	54	4	5	29	20
Liu ZW [17]	2015	China	Chinese	Asian	53	73	42/84	41.6	Siemens	SonoVue	47	7	6	66	22
Zhao Y [6]	2010	China	Chinese	Asian	17	22	6/31	41.1	GE	SonoVue	16	3	1	19	20
Pan JS [18]	2013	China	Chinese	Asian	17	72	10/71	42.7	-	SonoVue	13	2	4	70	22
Cantisani V [19]	2013	Italy	Chinese	European	19	34	13/35	49.4	Aplio XG	SonoVue	15	3	4	31	25
Nemec U [20]	2012	Australia	Chinese	Oceania	11	31	10/36	52.1	Philips	SonoVue	8	5	3	26	26
Deng J [21]	2014	China	Chinese	Asian	56	119	42/104	46.3	Siemens	SonoVue	46	18	10	101	23