Multifocal autoimmune pancreatitis: A retrospective study in a single tertiary center of 26 patients with a 20-year literature review

Table 1 Friedman analysis of variance by ranks for the diagnosis confidence level score

Groups	Junior radiologist	Senior radiologist
DWI	2.32	2.32
Axial-suppressed T1WI	1.95	2.07
Dynamic contrast enhanced CT	1.73	1.61
P value	0.033	0.004

CT: Computed tomography; DWI: Diffusionweighted imaging; T1WI: T1 weighted image.

Table 2 Interobserver agreement in image interpretation

Groups	κ-value
DWI	0.878
Axial fat-suppressed T1WI	0.742
Dynamic contrast enhanced CT	0.683

CT: Computed tomography; DWI: Diffusionweighted imaging; T1WI: T1 weighted image.

Table 3 Apparent diffusion coefficient values of autoimmune pancreatitis lesions compared with those of surrounding pancreatic tissue¹

	AIP lesions ADC	Surrounding parenchyma ADC	Wilcoxon signed-rank test
	Values (n = 56) (× 10-3 mm2/s)	Values (n = 56) (× 10-3 mm2/s)	Z value	P value
Mean	0.96	1.15	-5.11	0.001
SD	0.14	0.15
Median	0.96	1.16
Minimum	0.68	0.89
Maximum	1.26	1.40

¹Apparent diffusion coefficient values in autoimmune pancreatitis lesions were lower (0.96 ± 0.14) compared with those in the surrounding pancreatic parenchyma (1.15 ± 0.15), Wilcoxon signed-rank test demonstrated this difference to be statistically significant (P = 0.001). ADC: Apparent diffusion coefficient; AIP: Autoimmune pancreatitis; SD: Standard deviation.

Table 4 Comparison of radiological findings between patients with multifocal autoimmune pancreatitis and pancreatic ductal adenocarcinoma, n (%)

	Multifocal AIP	PDA	P value
No. of radiological findings of the pancreas	56	112
Multifocal lesion	56 (100)	2 (1.7)	< 0.01
Capsule-like rim	12 (21.4)	4 (3.6)	< 0.01
Delayed homogeneous enhancement on MDCT	52 (92.8)	15 (13.4)	< 0.01
Margin (indistinct)	48 (85.7)	89 (79.5)	0.325
Peripancreatic fat infiltration	26 (46.4)	102 (91.0)	< 0.01
Vascular invasion	8 (14.3)	80 (71.4)	< 0.01
Multiple MPD strictures	53 (47.3)	2 (1.8)	< 0.01
Marked upstream MPD dilatation	2 (3.6)	59 (52.7)	< 0.01
Upstream pancreatic atrophy	11 (19.6)	66 (58.9)	< 0.01
Lymphadenopathy	2 (3.6)	69 (61.6)	< 0.01
ADC values (× 10-3 mm2/s)	0.96 ± 0.16	1.15 ± 0.14	< 0.01

ADC: Apparent diffusion coefficient; AIP: Autoimmune pancreatitis; MDCT: Multidetector computed tomography; MPD: Main pancreatic duct; MRI: Magnetic resonance image; PDA: Pancreatic ductal adenocarcinoma.