Computed tomography and magnetic resonance imaging features of lipid-rich neuroendocrine tumors of the pancreas

Table 1 Magnetic resonance imaging sequences and parameters

	TR (ms)	TE (ms)	FA (°)	Thickness (mm)	ETL	Matrix Size	FOV (mm)
Chemical-shift MRI
2D dual GRE with 1.5-T system (n = 15)	128-133	2.2-2.4, 4.4-4.8	70-75	4-7	-	134-205 × 256	320-380
2D dual GRE with 3.0-T system (n = 4)	197-238	1.2, 2.4	60	5-5.5	-	192-200 × 192-200	350-360
3D dual GRE with 3.0-T system (n = 10)	5.8	1.2, 2.4	10	2.5	-	192 × 256	350
Fat-suppressed T2-weighted imaging
Breath-hold half-Fourier single-shot TSE with 1.5-T system (n = 9)	Infinity	90	90	4-7	138	256 × 256	320-380
Respiratory-triggered multi-shot TSE with 1.5-T system (n = 6)	Respiratory intervals	80-85	90	5-6	15	256 × 336	320-350
Respiratory-triggered multi-shot TSE with 3.0-T system (n = 14)	Respiratory intervals	70-80	90	4-6	11-18	256-384 × 320-512	320-360

CT: Computed tomography; MRI: Magnetic resonance imaging; GRE: Gradient-echo; TSE: Turbo spin-echo; TR: Repetition time; TE: Echo time; FA: Flip angle; ETL: Echo train length; FOV: Field of view.

Table 2 Comparison of clinical characteristics and TNM stage in 29 patients with lipid-rich or non-lipid-rich pancreatic neuroendocrine tumors

	Patients with lipid-rich PanNET (n = 12)	Patients with non-lipid-rich PanNET (n = 17)	P value
Age (yr)	52.6 ± 18.3	58.1 ± 15.0	0.4781
Sex			1.0002
Male	5	8
Female	7	9
Hormonal syndrome			1.0002
Functioning	6	8
Non-functioning	6	9
TNM stage			0.0481
I	3	11
II	6	4
III	1	1
IV	2	1

¹The P value levels shown were followed by the Mann-Whitney U test;

²The P value levels shown were followed by Fisher’s exact test. PanNET: Pancreatic neuroendocrine tumor.

Table 3 Comparison of histopathological findings in lipid-rich vs non-lipid-rich pancreatic neuroendocrine tumors

	Lipid-rich PanNET (n = 15)	Non-lipid-rich PanNET (n = 19)	P value
Tumor size (mm)	28.8 ± 26.2	20.5 ± 16.9	0.0391
Location			0.6792
Head	7	7
Body	5	5
Tail	3	7
Pathological grade			0.2882
Grade 1	8	14
Grade 2-3	7	5
Clear cells			< 0.0012
Present	8	0
Absent	7	19

¹The P value levels shown were followed by the Mann-Whitney U test;

²The P value levels shown were followed by Fisher’s exact test. PanNET: Pancreatic neuroendocrine tumor.

Table 4 Comparison of qualitative computed tomography and magnetic resonance imaging parameters in lipid-rich and non-lipid-rich pancreatic neuroendocrine tumors

Qualitative variables	Lipid-rich PanNET (n = 15)	Non-lipid-rich PanNET (n = 19)	P value	κ
Tumor margin			0.6972	0.92
Sharp	12	13
Irregular	3	6
Upstream pancreatic duct dilatation			0.6722	1.00
Present	4	3
Absent	11	16
Tumor attenuation on unenhanced CT			0.1281	0.99
Low	3	1
Iso	12	17
Mildly high	0	1
High	0	0
Tumor attenuation on early phase			0.8881	0.96
Low	0	2
Iso	2	0
Mildly high	4	5
High	9	12
Tumor attenuation on portal venous phase			0.4431	0.81
Low	0	1
Iso	4	6
Mildly high	6	7
High	5	5
Tumor attenuation on delayed phase			0.3591	0.75
Low	1	1
Iso	6	12
Mildly high	5	2
High	3	4
Tumor homogeneity on early phase			1.0002	0.77
Homogenous	8	11
Heterogeneous	7	8
Signal intensity on T2-weighted image			0.7981	0.98
Lower intensity	1	4
Same intensity	3	2
Mildly higher intensity	5	5
Higher intensity	6	8
Tumor homogeneity on T2-weighted image			0.4842	0.77
Homogenous	8	13
Heterogeneous	7	6
Signal intensity on in-phase image			0.6981	0.79
Lower intensity	14	17
Same intensity	1	2
Higher intensity	0	0
Signal intensity on out-of-phase image			0.0571	0.89
Lower intensity	13	10
Same intensity	1	8
Higher intensity	1	1
Intravoxel lipid on subtraction image			0.0292	1.00
Present	4	0
Absent	11	19

¹The P value levels shown were followed by the Mann-Whitney U test;

²The P value levels shown were followed by Fisher’s exact test. PanNET: Pancreatic neuroendocrine tumor; CT: Computed tomography.