Optimized study of virtual monoenergetic images derived from a dual-layer spectral detector CT in the preoperative evaluation of pancreatic ductal adenocarcinoma

doi:10.3969/j.issn.1674-8115.2022.09.020

Abstract

Abstract:

Objective ·To explore the optimal energy level of virtual monoenergetic images (VMIs) derived from a dual-layer spectral detector computed tomography (CT) and its application value in the preoperative evaluation of pancreatic ductal adenocarcinoma (PDAC). Methods ·From January 2019 to June 2019, the images of sixty patients who underwent pancreas dynamic enhanced scanning on a dual-layer spectral detector CT and were pathologically confirmed of PDAC in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine were retrospectively analyzed. The conventional 120 kVp polyenergetic image (PI), and 40, 50, 60, and 70 keV VMIs were generated. The CT values of lesions, normal pancreatic parenchyma, peripheral pancreatic arteries and veins, and abdominal subcutaneous fat were measured, and the contrast-to-noise ratios (CNRs) of cancer-pancreatic parenchyma (CA-P), artery-cancer (A-CA), and vein-cancer (V-CA) were calculated with the standard deviation (SD) of abdominal subcutaneous fat CT value as image noise. The differences were analyzed by using paired t test and one‐way ANOVA test. Pairwise comparisons within groups were performed by using the Bonferroni method. Subjective scores were obtained based on the lesion-pancreatic parenchyma contrast, lesion boundary definition, and the overall image quality, and compared by using Wilcoxon test and Friedman test. Results ·Among PI and all VMIs, the CNR_CA-P and the subjective scores of lesion-pancreas parenchyma contrast and the lesion boundary definition in pancreatic parenchymal phase were higher than those in portal vein phase (all P=0.000). The CNR_CA-P, CNR_A-CA, and CNR_V-CA of VMIs increased significantly as the energy level decreased from 70 keV to 40 keV, while the image noise only subtly increased (all P=0.000). The VMI_{40 keV}had the highest CNR_CA-P, CNR_A-CA, and CNR_V-CA with lower image noise than PI (all P=0.000). The subjective scores of VMI_{40 keV}were not lower than PI. Conclusion ·The VMI_{40 keV} derived from the dual-layer spectral detector CT performs a better image quality, and can significantly improve the CNR_CA-P, CNR_A-CA, and CNR_V-CA, which can optimize the preoperative imaging and the evaluation of pancreatic ductal adenocarcinoma.

Key words: pancreatic ductal adenocarcinoma (PDAC), dual-layer spectral detector CT, virtual monoenergetic image (VMI), image quality

CLC Number:

R445.3

YANG Yanzhao, CHANG Rui, WANG Qingrou, ZHU Naiyi, LI Ruokun, CHAI Weimin, YAN Fuhua. Optimized study of virtual monoenergetic images derived from a dual-layer spectral detector CT in the preoperative evaluation of pancreatic ductal adenocarcinoma[J]. Journal of Shanghai Jiao Tong University (Medical Science), 2022, 42(9): 1323-1328.

Figures/Tables 5

TrendMD

References 17

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Group	Pancreatic parenchyma		Cancer		Arteries
Group	CT number	SD	CT number	SD	CT number
PI	111.8±17.5	19.3±3.4	57.1±12.4	19.6±3.9	296.5±37.8
VMI_{40 keV}	274.6±54.0	18.1±3.8	116.1±37.8	20.0±4.5	899.0±136.7
VMI_{50 keV}	190.9±34.0	16.9±3.2	86.7±25.1	17.8±3.7	590.4±92.6
VMI_{60 keV}	141.0±23.1	16.0±2.7	68.4±17.0	16.7±3.2	413.7±59.6
VMI_{70 keV}	111.4±16.8	15.8±2.8	57.6±12.4	16.1±3.0	305.4±42.7

Group	Pancreatic parenchyma		Cancer		Arteries
Group	CT number	SD	CT number	SD	CT number
PI	111.8±17.5	19.3±3.4	57.1±12.4	19.6±3.9	296.5±37.8
VMI_{40 keV}	274.6±54.0	18.1±3.8	116.1±37.8	20.0±4.5	899.0±136.7
VMI_{50 keV}	190.9±34.0	16.9±3.2	86.7±25.1	17.8±3.7	590.4±92.6
VMI_{60 keV}	141.0±23.1	16.0±2.7	68.4±17.0	16.7±3.2	413.7±59.6
VMI_{70 keV}	111.4±16.8	15.8±2.8	57.6±12.4	16.1±3.0	305.4±42.7

Group	Pancreatic parenchyma		Cancer		Veins
Group	CT number	SD	CT number	SD	CT number
PI	108.9±11.4	20.3±3.8	67.5±14.9	20.7±3.9	190.6±27.0
VMI_{40 keV}	276.8±39.8	19.3±4.1	159.4±48.2	21.7±5.1	558.0±94.7
VMI_{50 keV}	190.6±24.5	17.8±3.4	112.0±29.6	19.2±4.0	371.9±61.1
VMI_{60 keV}	140.1±16.2	17.0±3.0	85.0±20.6	17.8±3.3	262.5±41.4
VMI_{70 keV}	110.2±11.4	16.5±2.9	69.3±15.1	17.0±3.3	196.5±29.6

Group	Pancreatic parenchyma		Cancer		Veins
Group	CT number	SD	CT number	SD	CT number
PI	108.9±11.4	20.3±3.8	67.5±14.9	20.7±3.9	190.6±27.0
VMI_{40 keV}	276.8±39.8	19.3±4.1	159.4±48.2	21.7±5.1	558.0±94.7
VMI_{50 keV}	190.6±24.5	17.8±3.4	112.0±29.6	19.2±4.0	371.9±61.1
VMI_{60 keV}	140.1±16.2	17.0±3.0	85.0±20.6	17.8±3.3	262.5±41.4
VMI_{70 keV}	110.2±11.4	16.5±2.9	69.3±15.1	17.0±3.3	196.5±29.6

Index	PI	VMI_{40 keV}	VMI_{50 keV}	VMI_{60 keV}	VMI_{70 keV}	F value	P value
CNR_CA-P
Parenchymal phase	2.9±0.9	8.9±2.6	6.3±1.9	4.6±1.4	3.5±1.1	118.585	0.000
Portal venous phase	2.1±1.0^①	6.2±3.2^①	4.5±2.2^①	3.3±1.6^①	2.5±1.2^①	42.555	0.000
Image noise
Parenchymal phase	13.1±2.4	11.8±2.5	11.1±2.0	10.7±1.8	10.5±1.7	15.062	0.000
Portal venous phase	13.7±2.4	12.5±2.6	11.7±2.3	11.2±2.1	11.0±1.9	14.692	0.000
CNR_A-CA	12.6±2.6	40.8±9.7	29.1±6.7	21.3±4.6	15.8±3.4	216.889	0.000
CNR_V-CA	6.1±1.6	19.1±5.9	14.0±4.0	10.2±2.8	7.6±2.0	126.199	0.000