Pancreatic volume change using three dimensional-computed tomography volumetry and its relationships with diabetes on long-term follow-up in autoimmune pancreatitis

Table 1 Computed tomography parameters

Parameter	HiSpeed Advantage1	Aquilion CX2 or Aquilion ONE3
No. of channels	1	16 or 320
Section collimation in mm	5	1
Section thickness in mm	5	1
Reconstruction interval in mm	2.5	1
Pitch	1.0	0.6-1.0
Tube current in mA	200-250	400-600
Tube voltage in kVp	120	120
Matrix	512 × 512	512 × 512

¹HiSpeed Advantage (General Electric Medical Systems, Chicago, IL, United States);

²Aquilion CX (Aquilion CX TSX-101A/NA; Toshiba Medical Systems, Co. Ltd., Tochigi, Japan);

³Aquilion ONE (Aquilion ONE TSX-301A/2A; Toshiba Medical Systems, Co. Ltd.).

Table 2 Clinical characteristics of patients with type-1 autoimmune pancreatitis in relation to diffuse or mass-forming type

Variable	All, n = 33	D-type, n = 16	M-type, n = 17	P valuea
Male:Female	24:09	12:04	12:05	1.00
Age at initial CT in years	63.1 ± 11.1 (65.0, 37-85)	64.6 ± 11.0 (65.0, 51-80)	61.6 ± 11.3 (64.5, 37-79)	0.66
Pancreatic re-enlargement	12 (36.4)	7 (43.8)	5 (29.4)	0.48
Mean time to first re-enlargement in months	42.5 ± 27.9 (37.5, 7-93)	50.7 ± 34.0 (52.0, 7-93)	31.0 ± 11.5 (30.0, 18-47)	0.33
Extrapancreatic lesions	9 (27.3)	9 (56.3)	0 (0.0)	< 0.001

Data presented as mean ± standard deviation (median and range) or number (percentage).

^aP values between diffuse and mass-forming types. CT: Computed tomography; D-type: Diffuse type; M-type: Mass-forming type.

Table 3 Follow-up period and pancreatic volume at initial and last follow-up computed tomography in patients with type-1 autoimmune pancreatitis

Variable	All, n = 33	D-type, n = 16	M-type, n = 17	P valuea
Follow-up period in months	95.8 ± 68.2 (65.0, 19-243)	109.8 ± 74.4 (70, 35-243)	82.6 ± 61.0 (65, 19-212)	0.26
Mean PV at initial CT in cm3	80.4 ± 25.9 (75.8, 36.2-136.0)	84.4 ± 31.4 (86.0, 36.2-136.0)	76.6 ± 19.8 (72.6, 43.9-117.5)	1
Mean relative PV change1 at last follow-up CT as %	37.6 ± 19.3 (32.2, 9.5-82.6)	27.4 ± 11.4 (23.5, 9.5-45.0)	47.1 ± 20.6 (31.0, 18.9-82.6)	0.007
Mean PV at last follow-up CT in cm3	29.0 ± 15.0 (23.2, 10.5-60.3)	22.6 ± 11.1 (19.8, 10.5-47.2)	35.1 ± 15.7 (31.7, 17.8-60.5)	0.013
Mean atrophy ratio of PV at last follow-up CT compared with normal PV as %2	59.3 ± 19.8 (65.5, 53.9-94.0)	68.1 ± 15.1 (69.6, 28.5-86.5)	51.0 ± 20.5 (58.9, 11.5- 77.0)	0.012

Data presented as mean ± standard deviation (median and range).

^aP values between diffuse and mass-forming types.

¹Relative pancreatic volume (PV) change = PV on follow-up computed tomography (CT)/PV on initial CT × 100 %;

²Atrophy ratio of the pancreatic volume (PV) was calculated by dividing the difference in the normal PV and PV at the time of last follow-up computed tomography by the normal PV. CT: Computed tomography; D-type: Diffuse type; M-type: Mass-forming type; PV: Pancreatic volume.

Table 4 Correlations between pancreatic volume and serum IgG4 levels in 20 patients with type I AIP during follow-up

D-type, n = 6	M-type, n = 7	Patients with extrapancreatic lesions (n = 7)1
-0.31 (0.456)	-0.70 (0.190)	-0.48 (0.230)
0.43 (0.144)2	0.10 (0.550)	-0.14 (0.790)
0.45 (0.224)2	0.29 (0.425)	0.03 (0.957)
0.48 (0.233)2	0.59 (0.045)2	0.03 (0.930)
0.85 (0.004)2	0.60 (0.048)2	0.05 (0.910)
0.86 (0.014)2	0.90 (0.037)2	0.45 (0.260)
-	0.98 (0.005)2	0.60 (0.285)

¹Data given as correlation coefficient (P value);

²Moderate-to-very strong significant positive correlation. D-type: Diffuse type; M-type: Mass-forming type.

Table 5 Incidence of diabetes in patients with type-1 autoimmune pancreatitis at the time of initial and follow-up computed tomography

Diabetes	Initial CT			Last follow-up CT
	All	D-type	M-type	All	D-type	M-type
Yes	19	11	8	20	13	7
No	14	5	9	13	3	10

CT: Computed tomography; D-type: Diffuse type; M-type: Mass-forming type.