Evaluation value of single-phase images from photon-counting CT-based low-dose pancreatic dynamic volume perfusion scanning for pancreatic cancer imaging

doi:10.16150/j.1671-2870.2025.02.006

Abstract

Abstract:

Objective This study aims to evaluate the image quality of single-phase images in low-dose pancreatic dynamic volume perfusion computed tomography (VPCT) scans based on photon-counting computed tomography (PCCT) and assess their feasibility for morphological evaluation of pancreatic ductal adenocarcinoma (PDAC). Methods From April to August 2024, participants suspected of PDAC were prospectively enrolled and underwent preoperative pancreatic VPCT scans. A total of 55 patients with pathologically confirmed PDAC were included, and radiation doses were recorded and calculated. Perfusion time-attenuation curves were analyzed, and optimal single-phase images of pancreatic parenchymal phase and portal venous phase were extracted from T3D, 55 keV, and 70 keV virtual monoenergetic images (VMIs) for clinical diagnosis and morphological evaluation of PDAC. Subjective scoring of images was performed, and CT values of lesions, normal pancreatic parenchyma, peripancreatic vessels, and abdominal wall fat were measured. The standard deviation of the CT value of abdominal wall fat was used as the image noise value. Signal-to-noise ratios (SNRs) of lesions, normal pancreatic parenchyma, and peripancreatic vessels, as well as contrast-to-noise ratios (CNRs) of lesions and peripancreatic vessels were calculated. Inter-observer agreement of subjective evaluations was evaluated using Cohen's kappa coefficient. One-way repeated measures ANOVA and Friedman H tests were used to compare the quantitative evaluation indicators and subjective scores among groups. Results The VPCT scanning achieved an average effective radiation dose of (18.0±4.9) mSv. The single-phase images of pancreatic parenchymal phase and portal venous phase extracted from reconstructed images met clinical diagnostic quality standards, with all subjective image quality scores above 3 points. In the single-phase images of pancreatic parenchymal phase reconstructed at 55 keV VMI, the CNR of PDAC lesions was 11.1±4.4, while for T3D it was 9.1±3.7 and for 70 keV VMI it was 8.0±3.2. In images of portal venous phase reconstructed at 55 keV VMI, the CNR of PDAC lesions was 6.3±3.0, while for T3D it was 5.7±3.0 and for 70 keV VMI, it was 4.9±2.7. Single-phase images reconstructed from 55 keV VMI showed the highest CNR of PDAC lesions (P<0.001), along with the highest SNR of normal pancreatic parenchyma and peripancreatic vessels, the highest CNR of peripancreatic vessels, and optimal subjective contrast scores of PDAC lesions. There was no significant difference in image noise between 55 keV VMI and T3D reconstructed single-phase images [parenchymal phase: (8.3±2.1) vs. (8.2±2.1), portal venous phase: (8.4±2.1) vs. (8.3±2.2)] (P=0.599, 0.683). Both had higher image noise than that of 70 keV VMI (parenchymal phase: 7.1±1.9, portal venous phase: 7.3±1.8) (P<0.001). Conclusion Single-phase images obtained from perfusion scanning PCCT-based low-dose pancreatic dynamic VPCT imaging protocols can be used for PDAC imaging and morphological evaluation. The 55 keV VMI reconstruction can further optimize the image quality of PDAC.

Key words: X-ray computed tomography, Photon-counting CT, CT perfusion imaging, Image quality, Radiation dosage

CLC Number:

R814.42

CHANG Rui, LI Jiqiang, YANG Yanzhao, CHAI Weimin, YAN Fuhua, DONG Haipeng.. Evaluation value of single-phase images from photon-counting CT-based low-dose pancreatic dynamic volume perfusion scanning for pancreatic cancer imaging[J]. Journal of Diagnostics Concepts & Practice, 2025, 24(02): 155-162.

Figures/Tables 5

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Acquisition parameters Parameter
Scan mode	PCCT（NAEOTOM Alpha）
Tube voltage (kVp)	90
Image quality (IQ) level	80
Tube current	Care Dose 4D
Spiral pitch	1.0
Rotation time（s）	0.25
Collimation（mm）	144 × 0.4
Total acquisition time（s）	47（began at 7）
Z-axis coverage ^*（cm）	16 - 25
Number of scan cycles ^†	17 - 23
Contrast Volume（mL）	40
Iodine concentration（mg/mL）	400
Flow rate（mL/s）	4
Reconstruction Parameters
Quantum iterative reconstruction	QIR 4
Reconstruction filter kernel	Br 40
Slice thickness and increment (mm)	1 / 1
Image reconstruction	55 keV / 70 keV / T3D

Parameter	Value
Sex	Male 34，Female 21
Age（y）	66.4 ± 6.6 (49-78)
Weight（kg）	62.5 ± 10.2 (40-83)
Height（m）	1.66 ± 0.90 (1.45-1.86)
BMI（kg/m²）	22.7 ± 3.2 (17.6-32.9)
Z-axis range（cm）	18.7 ± 2.2 (16-25)
No. of scan cycles	20 ± 2.0 (17-23)
CTDIvol（mGy）	58.7 ± 14.6 (28.3-95.4)
DLP（mGy · cm）	1199.4 ± 328.8 (472.5-1 943.1)
ED（mSv）	18.0 ± 4.9 (7.1-29.2)

Item	T3D	70 keV	55 keV	P^*	P^†	P^‡	P^§
Pancreatic parenchymal phase
Image noise (HU)	8.2 ± 2.1	7.1 ± 1.9	8.3 ± 2.1	< 0.001	< 0.001	0.599	< 0.001
SNR parenchyma	16.3 ± 5.9	16.7 ± 5.0	18.8 ± 6.4	< 0.001	0.002	< 0.001	< 0.001
SNR vessel	35.9 ± 15.9	36.1 ± 12.5	46.8 ± 19.8	< 0.001	< 0.001	< 0.001	< 0.001
SNR lesion	7.2 ± 1.8	7.5 ± 2.1	7.6 ± 2.0	0.036	0.062	0.003	0.505
CNR vessel	27.0 ± 17.7	25.7 ± 16.2	36.9 ± 23.0	< 0.001	< 0.001	< 0.001	< 0.001
CNR lesion	9.1 ± 3.7	8.0 ± 3.2	11.1 ± 4.4	< 0.001	< 0.001	< 0.001	< 0.001
Portal venous phase
Image noise (HU)	8.3 ± 2.2	7.3 ± 1.8	8.4 ± 2.1	< 0.001	< 0.001	0.683	< 0.001
SNR parenchyma	12.4 ± 3.2	11.8 ± 3.2	13.3 ± 3.6	< 0.001	0.033	< 0.001	< 0.001
SNR vessel	20.9 ± 6.3	18.5 ± 5.0	23.3 ± 7.5	< 0.001	< 0.001	< 0.001	< 0.001
SNR lesion	6.5 ± 2.0	6.7 ± 1.9	6.9 ± 2.2	0.003	0.009	< 0.001	0.231
CNR vessel	10.6 ± 4.4	9.0 ± 3.7	13.5 ± 5.7	< 0.001	< 0.001	< 0.001	< 0.001
CNR lesion	5.7 ± 3.0	4.9 ± 2.7	6.3 ± 3.0	< 0.001	< 0.001	< 0.001	< 0.001