Common bile duct stones on multidetector computed tomography: Attenuation patterns and detectability

Table 1 Correlation between the attenuation patterns of common bile duct stones on multidetector computed tomography and stone type (n = 111)

	Stone type,n(size, mean ± SD, mm)
Attenuation patterns	Black pigment	Mixed cholesterol	Brown pigment	Pure cholesterol	Overall
Heavily calcified	15	14	5	0	34
	(6.1 ± 3.4)	(7.0 ± 3.2)	(9.2 ± 4.1)		(6.9 ± 3.5)
Radiopaque	3	12	16	0	31
	(7.0 ± 1.0)	(10.2 ± 4.3)	(13.6 ± 4.8)		(11.6 ± 4.8)
Less radiopaque1	3	10	33	0	46
	(5.7 ± 4.0)	(7.6 ± 3.5)	(9.9 ± 5.1)		(9.1 ± 4.8)
Overall	21	36	54	0
	(6.2 ± 3.1)	(8.2 ± 3.6)	(10.9 ± 5.1)

¹Including six less radiopaque stones with gas attenuation. P < 0.001.

Table 2 Detectability of common bile duct stones according to stone size and stone type n (%)

	n	Detectable (n = 111)	Undetectable (n = 19)	P value
Size (mm)
< 3	9	4 (44)	5 (56)	< 0.001
3–5	40	29 (74)	11 (26)
6–10	45	43 (96)	2 (4)
11–15	26	25 (96)	1 (4)
> 15	10	10 (100)	0 (0)
≤ 5	49	33 (67)	16 (33)	< 0.001
> 5	81	78 (96)	3 (4)
Type
Black pigment	23	21 (91)	2 (9)	< 0.001
Mixed cholesterol	38	36 (95)	2 (5)
Brown pigment	60	54 (90)	6 (10)
Pure cholesterol	9	0 (0)	9 (100)
Black or mixed	61	57 (93)	4 (7)	0.023
Brown or pure cholesterol	69	54 (78)	15 (22)

Table 3 Univariate analysis of the factors related to the detectability of common bile duct stones by multidetector computed tomography n (%)

Factors	Detectable(n = 111)	Undetectable(n = 19)	P value
Age (yr)	68.3 ± 14.2	58.0 ± 16.2	0.009
Male sex	58 (52)	9 (47)	0.966
Accompanying GB stones	43 (39)	11 (58)	0.117
Previous cholecystectomy	28 (25)	3 (16)	0.561
Previous sphincterotomy	13 (12)	0 (0)	0.213
Black or mixed stone	57 (51)	4 (21)	0.009
Stone size (mm)	9.1 ± 4.8	4.3 ± 2.9	< 0.001
CBD diameter (mm)	12.4 ± 4.6	9.2 ± 3.5	0.005
WBC (× 109/L)	10.9 ± 6.01	9.86 ± 3.07	0.251
Alanine aminotransaminase (IU/L)	210 ± 250	250 ± 208	0.513
Total bilirubin (mg/dL)	3.8 ± 3.9	3.3 ± 2.8	0.565
Alkaline phosphatase (IU/L)	215 ± 153	209 ± 114	0.862
γ-glutamyl transferase (IU/L)	412 ± 342	500 ± 465	0.327

CBD: Common bile duct; WBC: White blood cell.

Table 4 Multivariate analysis of the factors related to the detectability of common bile duct stones by multidetector computed tomography

Factors	P value	Odds ratio (95%CI)
Age	0.032	1.049 (1.004-1.095)
Stone type (black or mixed vs brown or pure cholesterol)	0.002	8.851 (2.249-34.84)
Stone size	0.001	1.437 (1.153-1.791)
CBD diameter	0.538

CBD: Common bile duct.