Focal autoimmune pancreatitis: Radiological characteristics help to distinguish from pancreatic cancer

Table 1 Comparison of imaging findings

Imaging features	Data of assessable patients		Kappa	P
	f-AIP (n = 19)	f-PC (n = 30)
Sausage-shaped enlargement	0.58 (11/19)	0.03 (1/30)	0.58	< 0.001
Delayed homogeneous enhancement	1.00 (19/19)	0.1 (3/30)	0.88	< 0.001
Hypoattenuating capsule-like rim	0.63 (12/19)	0.03 (1/30)	0.64	< 0.001
Distal pancreatic atrophy	0.30 (3/10)	0.95 (20/22)	-0.55	< 0.001
MPD
Normal	0 (0/19)	0 (0/30)		NS
Irregular narrowing	0.58 (11/19)	0.06 (2/30)	0.05	NS
Complete obstruction	0.42 (8/19)	0.93 (28/30)	-0.06	NS
CBD
Normal	0.53 (10/19)	0.47 (14/30)	-0.36	0.027
Stenosis1	0.29 (4/14)	0 (0/14)	0.3	0.022
Complete obstruction	0 (3/19)	0.53 (16/30)	-0.38	< 0.01
MPD upstream dilation ≤ 5 mm	1.00 (10/10)	0.14 (5/22)	0.66	< 0.001
Affected location of pancreas
Head	0.26 (5/19)	0.53 (16/30)	-0.08	NS
Body	0.26 (5/19)	0.2 (6/30)	-0.27	NS
Tail	0.47 (9/19)	0.27 (8/30)	0.11	NS
Other findings
Vascular invasion	0 (0/19)	0.13 (4/30)	-0.17	NS
Pancreatic lymph node	0.16 (3/19)	0.87 (26/30)	-0.65	< 0.001
Calcification	0 (1/19)	0 (0/30)		NS

Data are percentages and numbers in parentheses refer to numbers of lesions.

¹The stenosis of common bile duct (CBD) was not evaluated for focal autoimmune pancreatitis (f-AIP) and pancreatic cancer (PC) patients with lesions in the pancreatic head. When the Kappa value was negative, the corresponding item was not suitable for differentiation. f-AIP: Focal autoimmune pancreatitis; MPD: Main pancreatic duct; NS: Not significant.

Table 2 Mean computed tomography attenuation values

Group	n	Condition	Unenhanced scan (HU)	Arterial phase (HU)	Pancreatic phase (HU)	Hepatic phase (HU)
f-AIP	19	Lesions	36 ± 4	60 ± 7	85 ± 6	95 ± 7
		Uninvolved pancreas	42 ± 5	83 ± 10	105 ± 14	95 ± 7
		Liver	57 ± 4	68 ± 8	119 ± 15	100 ± 10
		Spleen	48 ± 3	111 ± 15	129 ± 15	96 ± 9
PC	30	Lesion	34 ± 5	48 ± 10	63 ± 15	63 ± 13
		Uninvolved pancreas	39 ± 6	76 ± 14	103 ± 15	87 ± 12
		Liver	58 ± 6	69 ± 9	108 ± 17	102 ± 10
		Spleen	46 ± 4	102 ± 19	141 ± 18	101 ± 7
Normal	30	Pancreas	44 ± 7	87 ± 12	105 ± 20	93 ± 10
		Liver	57 ± 7	65 ± 8	110 ± 18	99 ± 13
		Spleen	47 ± 4	107 ± 17	133 ± 23	99 ± 11

Data are computed tomography attenuation values (mean ± SD). f-AIP: Focal autoimmune pancreatitis; PC: pancreatic cancer.