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Objective:To explore the value of multiphasic CT-based radiomics signature in predicting the invasive behavior of pancreatic solid pseudopapillary neoplasm (pSPN).Methods:The multiphasic CT images of patients with pSPN confirmed by postoperative pathology in the First Affiliated Hospital of Zhengzhou University from January 2012 to January 2021 were analyzed retrospectively. There were 23 cases of invasiveness and 59 cases of non-invasiveness. The region of interest(ROI) was artificially delineated layer by layer in the plain scan, arterial-phase and venous-phase images, respectively. The 1 316 image features were extracted from each ROI. The data set was divided into training and validation sets with a ratio of 7∶3 by stratified random sampling, and synthetic minority oversampling technique (SMOTE) algorithm was used for oversampling in the training set to generate invasive and non-invasive balanced data for building the training model. The constructed model was validated in the validation set. The receiver operating characteristic(ROC) analysis was used to evaluate model performance and the Delong′s test was applied to compare the area under the ROC curve (AUC) of different predict models. The improvement for classification efficiency of each independent model or their combinations were also assessed by net reclassification improvement (NRI) and integrated discrimination improvement (IDI) indices.Results:After feature extraction, 2, 6 and 3 features were retained to construct plain-scanned model, arterial-phase and venous-phase models, respectively. Seven independent-phase and combined-phase models were established. Except the plain-scanned model, the AUC values of other models were greater than 0.800. The arterial-phase model had the best efficiency for classification among all independent-phase models. The AUC values of arterial-phase model in the SMOTE training and validation sets were 0.913 and 0.873, respectively. By combining the radiomics signature of the arterial-phase and venous-phase models, the AUC values of training and validation sets increased to 0.934 and 0.913 respectively. There were no significant differences of the AUC values between the scan-arterial venous-phase model and arterial venous-phase model in both training and validation sets (both P>0.05). The NRI and IDI indexes showed that the combined form of plain-scan model and arterial-venous-phase model could not significantly improve the classification efficiency in the validation set (both NRI and IDI<0). Conclusions:The arterial-phase CT-based radiomics model has a good predictive performance in the invasive behavior of pSPN, and the combination with a venous-phase radiomics model can further improve the model performance.
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Objective:To investigate the efficiency of deep learning image reconstruction (DLIR) algorithm in the image quality and detection of hypovascular hepatic metastases under low radiation doses in comparison with adaptive statistical iterative construction-V (ASiR-V).Methods:Fifty-six patients with suspected hypovascular hepatic metastases who needed abdominal enhanced CT scans were collected prospectively in the First Affiliated Hospital of Zhengzhou University from January to April 2021. The patients received conventional radiation dose with tube current-time products of 400 mA CT scans in the first venous phase, low-dose CT scans in the second venous phase, which were set as tube current-time products of 280 mA for group A (19 cases), 200 mA for group B (19 cases) and 120 mA for group C (18 case), respectively. The images of first venous phase and 3 groups of second venous phase were both reconstructed with ASiR-V60% and high-DLIR (DLIR-H). Quantitative parameters [image noise, liver and portal vein signal to noise ratio (SNR), contrast to noise ratio (CNR)] and qualitative parameters (overall image quality, lesion conspicuity, diagnostic confidence) were compared between ASiR-V60% and DLIR-H images, and the effective radiation dose (ED) and the lesion detectability of each group was recorded. The paired t test was used to compare quantitative parameters, whereas the Wilcoxon signed-rank test of paired data was used to compare qualitative parameters. Results:In the second venous phase, ED was (5.56±0.35) mSv in group A, (3.88±0.23) mSv in group B, and (2.42±0.23) mSv in group C, with a decrease of 30%, 50% and 70% compared with the first venous phase, respectively. Moreover, with the decrease of radiation dose, the noise gradually increased, and the CNR lesions, SNR liver and SNR portal vein all gradually decreased. DLIR-H images had statistically better quantitative scores than ASiR-V60% images when the same radiation dose was applied (all P<0.001). Furthermore, the qualitative parameters of each group decreased with the decrease of radiation dose. Under the same radiation dose, the overall image quality, lesion conspicuity and diagnostic confidence of DLIR-H were higher than those of ASiR-V60% (all P<0.001). All lesions [100% (84/84)] were detected by ASIR-V60% and DLIR-H in group A, 92.0% (75/81) in group B, and 88.0% (79/89) in group C. Conclusions:Compared with ASiR-V60%, DLIR-H could reduce image noise, improve overall image quality and lesion conspicuity of hypovascular hepatic metastases as well as increase diagnostic confidence under different radiation doses.
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Objective:To investigate the application value of spectral computed tomo-graphy (CT) multi-parameter imaging in predicting gastric cancer lymph node metastasis.Methods:The retrospective case-control study was conducted. The clinicopathological data of 86 patients with gastric cancer who were admitted to the First Affiliated Hospital of Zhengzhou University from January 2014 to June 2017 were collected. There were 53 males and 33 females, aged from 22 to 87 years, with a median age of 53 years. All patients received abdominal plain scan and arterial and venous phase contrast spectral scan. Images of plain scan, 70 keV monochromatic and iodine-based images in arterial and venous phase were analyzed on post-processing working station. Observation indicators: (1) gastric cancer lymph node metastasis; (2) analysis of influencing factors for lymph node metastasis in gastric cancer; (3) introduction of special cases. Count data were described as absolute numbers. Univariate analysis was performed using the chi-square test or rank sum test. Multivariate analysis was conducted using the Logistic regression model.Results:(1) Gastric cancer lymph node metastasis: of the 86 patients, 64 cases had lymph nodes metastasis and 22 had no lymph nodes metastasis. (2) Analysis of influencing factors for lymph node metastasis in gastric cancer: results of univariate analysis showed that tumor growth pattern, tumor diameter, infiltration of peritumor fat, CT value in arterial phase, CT value in venous phase, iodine value in venous phase were related factors affecting lymph nodes metastasis in gastric cancer ( χ2=6.753, Z=-3.180, χ2=7.649, Z=-2.051, -2.971, -2.547, P<0.05). Results of multivariate analysis showed that infiltration of peritumor fat and the iodine value in venous phase were greater than 12(100 μg/cm 3) and not greater than 16(100 μg/cm 3), or greater than 16(100 μg/cm 3) were independent risk factors affecting lymph nodes metastasis in gastric cancer ( odds ratio=13.154, 3.761, 7.583, 95% confidence interval as 2.597-66.620, 1.893-8.572, 4.769-16.692, P<0.05). (3) Introduction of special cases: case 1 was male, aged 46 years. Results of preoperative spectral CT enhanced scan showed gastric antrum space occupying lesion combined with enlarged lymph nodes. During enhancement arterial phase, spectral CT 70 keV monochromatic images and corresponding iodine-based images of primary lesion layer in the transverse view showed gastric wall thickening with mild to moderate enhancement, clear fat space in serosa and enlarged lymph nodes in lesser curvature. The spectral CT 70 keV monochromatic images and corresponding iodine-based images below pylorus level in the transverse view showed subpyloric enlarged lymph nodes. During enhancement venous phase, the 70 keV monochromatic images and corresponding iodine-based images of primary lesion layer in the transverse view showed layered enhancement of gastric antrum lesions and mucosal enhancement, with a high iodine value. The patient was diagnosed as gastric antrum cancer with lymph node metastasis, no serosal or peritumoral fat invasion. Results of postoperative pathological examination showed moderately differentiated adenocarcinoma of gastric antrum with serosal invasion and lymph node metastasis. Case 2 was male, aged 53 years. Results of preoperative spectral CT enhanced scan showed gastric cancer of lesser curvature combined with enlarged lymph nodes. During enhancement arterial phase, 70 keV monochromatic images and corresponding iodine-based images of primary lesion layer in the transverse view showed gastric wall heterogeneous thickening of lesser curvature, with moderate enhancement, obscure peritumor fat space, unclear serosa, and multiple enlarged lymph nodes in lesser curvature. During enhancement venous phase, 70 keV monochromatic images in the transverse view showed unclear boundary between lesions and enlarged lymph nodes in lesser curvature, obscure peritumor fat. During enhancement arterial phase, 70 keV monochromatic images of celiac trunk layer in the transverse view showed parasplenic artery lymph nodes, with circular enhancement and no enhancement in central necrotic elements. The patient was diagnosed as gastric cancer of lesser curvature with lymph node metastasis, serosal and peritumor fat invasion. Results of postoperative pathological examination showed poorly differentiated adenocarcinoma of gastric antrum with serosal invasion and lymph node metastasis. Conclusion:The infiltration of peritumor fat and iodine value in venous phase are independent factors affecting gastric cancer lymph node metastasis.
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Objective: To explore the value of specific spectral CT in evaluating antiangiogenic efficacy of Axitinib in rabbit VX2 liver tumors. Methods: Forty VX2 liver tumor-bearing rabbits were randomly assigned into study group (n=25, given Axitinib through intragastric administration for 14 days) and control group (n=15, given equal volume of normal saline through intragastric administration for 14 days). Rabbits in study group were scanned with one-stop perfusion and spectral CT mode, while in control group underwent arterial-phase spectral CT scan and perfusion CT scan, sequentially. The optimal scan time for control group was the maximum tumor contrast time based on the time-intensity curve of perfusion CT data of study group. The correlation coefficients of tumor perfusion parameters and the normalized iodine concentration (NIC) at different phases in study group were compared. Correlations between imaging features and vascular endothelial growth factor receptor-2 (VEGFR-2), and the differences among correlation coefficients were analyzed. Results: In control group, 73.33% (11/15) tumors achieved maximum contrast by using the optimal arterial scan time ([18±4]s) acquired from study group. The tumor blood flow (BF), blood volume (BV) and hepatic arterial fraction (HAF) had positive correlations with NIC. No statistical difference of correlation coefficients acquired in the optimal scan time and in the maximum correlation was found except for tumor BV. The tumor BF (r=0.828, P=0.008) and NIC (r=0.820, P=0.010) were positively correlated with VEGFR-2,while PS was negatively correlated with VEGFR-2 (r=-0.782, P=0.010), no statistical difference was found among the above three correlation coefficients (P>0.05). Conclusion: Single-phase contrast-enhanced spectral CT scan at tumor-specific and individual-specific acquisition time might be able to replace perfusion CT in evaluating antiangiogenic efficacy of Axitinib in rabbit VX2 liver tumors.
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Objective To investigate the clinical feasibility of spectral monochromatic imaging combined with adaptive statistical iterative reconstruction-V (ASIR-V) in upper abdominal enhanced scanning with double-low technique for severe liver cirrhosis.Methods Totally 126 cases performed abdominal contrast-enhanced CT scanning were collected prospectively and assigned to 3 groups with 42 cases in each group with random number table method.The filtered back projection algarithm,120 kV and contrast agent dose of 420 mgI/kg were used for the cases of control group.The cases for spectral group and combined group were scanned with spectral imaging mode and contrast agent dose of 300 mgI/kg.The 60 keV monochromatic images combined with pre-0％ and post-40％ ASIR-V were selected and analyzed for spectral group.Combined group with pre-40％ ASIR-V was divided into 2 subgroups with 50 keV,post -50％ ASIR-V and 60 keV,post-40％ ASIR-V separately.One-way ANOVA test was used for analysis of radiation dose and quantitative parameters,and Rank sum test was used for image subject evaluation.Results The CT numbers and CNR had significant differences among spectral group,combined group and control group(F=4.293-13.134,P＜0.05) except for the images of liver parenchyma in PVP and that of 50 keV combined 50％ASIR-V group were higher than that of control group (q=1.825-3.736,P＜0.05).No significant differences existed for image noise and overall image quality scores of organs in four groups.The visualization of hepatic vascular branches in 50 keV combined 50％ASIR-V group was higher than that of other three groups(Z=2.793-6.328,P＜0.05).The radiation dose of combined group was lower than that of spectral and control group (q =-4.879--2.531,P ＜ 0.001).Conclusions Spectral monochromatic imaging combined with pre-and post-ASIR-V can reduce contrast agent dose and radiation dose without degrading image quality for the severe liver cirrhosis in upper abdominal enhanced scanning.
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Objective To investigate the image quality and radiation dose of spectral CT with automatic spectral imaging mode selection (ASIS) and adaptive statistical iterative reconstruction (ASIR) at abdominal CT as compared with low-kVp CT with ASIR.Methods Two hundred patients underwent the plain and arterial-phase (AP) and portal venous-phase (PVP) contrast-enhanced abdominal CT scan were analyzed prospectively.The patients were randomly assigned to the control group (low-kVp CT scan) and study group (spectral CT scan),if BMI ≤ 23.9 kg/m2,patients were assigned into group A (80 kVp) or group B (spectral CT with ASIS);if 24.0 kg/m2 ≤ BMI＜28.9 kg/m2,patients were assigned into group C (100 kVp) or group D (spectral CT with ASIS)(n=50 each).Groups A and B,groups C and D were matched by gender,age,body mass index,cross sectional area and contrast agent dose respectively.Low-kVp images and monochromatic images (40 to 60 keV) were all reconstructed by using ASIR.Radiation dose and quantitative parameters (image noise in HU and contrast-to-noise ratio of the liver,aorta and portal vein) were compared by using t test while overall image quality was assessed by Mann-Whitney U test between the matched groups.Results Radiation dose in the group B was significantly higher than group A (increased by 10％,P＜0.05) but there was no significant differences between groups C and D (P＞0.05).Compared to the control group,image noises in the study group were higher at 40 keV and 50 keV (P＜0.05),but similar at 40 keV (P＞0.05).At the energy level of 40 keV,the study group showed higher CNRs,but lower overall image quality scores than the control group except for the similar image quality scores between groups A and B during AP (P＜0.05).At the energy level of 50 keV,the CNRs and overall image quality scores in the study group were higher than or similar to the control group.At the energy level of 60 keV,the study group showed lower or similar CNRs,but higher or similar overall image quality scores compared with the control group.Conclusions The radiation dose of spectral CT with ASIS technique was slightly higher than 80 kVp CT but similar to 100 kVp CT.By combining ASIR technique,monochromatic image at 50 keV can maintain or improve CNR and overall image quality as compared with low-kVp images.
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Objective To investigate the value of wide-detector helical CT combined with adaptive statistical iterative reconstruction-V (ASIR-V) in the low radiation dose CT examination of upper abdomen in obese patients.Methods In the first phantom experiment part,the optimal percentage of pre-and post-ASIR-V of abdominal scanning (120 kVp,NI =10 HU) were explored.The second human experiment was performed based on the phantom study,and our institutional review board approved this prospective study,each participant provided written informed consent.87 obese patients (body mass index,BMI ≥30 kg/m2) underwent contrast-enhanced abdominal CT scan were randomly divided into two scan protocols [protocol A:n =43,120 kVp,detector coverage of 80 mm,40％ pre-ASIR-V (group A1)and combined with 60％ post-ASIR-V (group A2) respectively;protocol B,n =44,120 kVp,detector coverage of 40 mm,40％ ASIR (group B)].Quantitative parameters [image noise and contrast-to-noise ratio (CNR)] and qualitative visual parameters (overall image quality as graded on a 5-point scale) were compared.Weighted effective dose (E) were assessed.Results The optimal percentage of pre-and post-ASIR-V of abdominal scanning were 40％ and 60％,respectively.The effective radiation dose in protocol A [(4.55 ± 0.95) mSv] was decreased for 53％ as compared with protocol B [(9.58 ± 2.04) mSv](t =-14.773,P ＜ 0.001).During the arterial phase and portal venous phase,except for the CNRs of liver,Group A2 showed higher CNRs (q =2.160-3.209,P ＜ 0.05),lower image noise(q =-4.212--3.202,P＜0.05),and higher overall image quality scores(Z =-5.155--2.561,P ＜0.05) as compared with group A1 and group B.Group A1 showed similar CNRs,similar image noise(P ＞ 0.05),and lower overall image quality scores (Z =-3.298--3.030,P ＜ 0.05) than group B.The overall image quality scores in group A were all greater than 3 point and met the clinical diagnostic level.Conclusions Compared with stand-detector helical CT in obese patients,the wide-detector helical CT combined with 40％ pre-ASIR-V could reduce the radiation dose by 53％,and improve overall image quality by combining post-ASIR-V technique.
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Objective To observe the impact of adaptive statistical iterative reconstruction-V (ASiR-V) on image quality and radiation dose in abdominal CT imaging,and to optimize combination of pre-and post ASiR-V percentage.Methods Totally 160 patients underwent plain and contrast-enhanced abdominal CT were randomly divided into study group or control group (each n=80).In study group,plain images were reconstructed with 20％ pre ASiR-V combined with 20％,40％,60％ and 80％ post-ASiR-V,the arterial phase images were reconstructed with 40％ pre-ASiR V combined with 40％,60％ and 80％ post-ASiR-V,while the venous phase images with 60％ pre-ASiR-V combined with 60％ and 80％ post-ASiR-V,and the delayed phase images with 80％ pre-ASiR-V combined 80％ post-ASiR-V.In control group,images were reconstructed with filtered back projection (FBP) and 0 pre-ASiR-V combined post-ASiR-V (20％ in plain,40％ in arterial phase,60％ in venous phase and 80％ in delayed phase imaing).The objective parameters (image noise [SD] and CNR) and image quality scores were analyzed and compared.Results CT dose index,dose length product and effective dose of each phase in study group were lower than those in control group (all P＜0.001).In study group,with the increasing of post-ASiR-V percentage,SD values gradually decreased (P＜0.01),and CNR gradually increased or did not change.With the increasing of post-ASiR-V (20％-60％),image quality scores increased,and image quality of 80 ％ post-ASiR-V was low.In study group,image quality of 20％ pre-ASiR-V combined 40％ or 60％ post-ASiR-V was similar to 20％ post-ASiR-V image in control group in plain,and that of 40％ pre-ASiR-V combined 60％ post-ASiR-V was similar to 40％ post-ASiR-V image in control group in arterial phase (all P＞0.05),while image quality scores of other combinations of pre-and post-ASiR-V percentages were lower than those in control group.Conclusion ASiR-V can improve abdominal CT image quality,and 40％ pre-ASiR-V combined 60％ post-ASiR V is recommended.
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Objective To evaluate the influence of preset adaptive statistical iterative reconstruction-V (ASIR-V) techniques on image quality and radiation dose reduction of abdominal CT in phantom,and to investigate the optimal ASIR-V level.Methods Abdominal anthropomorphic phantom was scanned using Revolution CT,when noise index (NI) were set as 6,8,10,12 and 14,respectively.Then 0-100％ ASIR-V and conventional scan was performed and 55 sets of images were obtained.CT value,noise,subjective score and radiation dose were recorded,and the optimal ASIR-V was obtained.Subjective scores of images in each group were compared using rank sum test,and CT value,noise and radiation dose were compared with one way ANOVA and paired t test.Results The image subjective score unchanged when NI was 6,8 or 10,slightly increased when NI was 12 and 14 with 0-40％ ASIR-V,and decreased above 50％ ASIR-V at all NI.When NI was 6,8 or 10,more than 70％ ASIR-V image subjective score fell below 3 points.When NI was 12 or 14 group,more than 60％ ASIR V subjective score fell below 3 points.The image quality score of conventional scan had no difference with 40％ ASIR-V when NI was 6,8 or 10,respectively (P=0.626,0.915,0.514),and inferior to 40％ ASIR-V when NI was 12 or 14 (P=0.041,0.036),while in all NI group,image quality score of conventional scan was superior to 60％ ASIR-V (P=0.021,0.012,0.015,0.014,0.007).CT values and image noises had no significant differences in different parts in all NI groups (all P＞0.05).CT dose index volume (CTDIvol) continuing decreased with ASIR-V.Compared with that of conventional scan,at 40％,50％ and 60％ ASIR-V,CTDIvol reduced by 49.82％,62.51％ and 71.63％,respectively.Conclusion Preset ASIR-V can reduce radiation dose obviously while maintaining the overall image quality,and 40％-60％ ASIR-V can be recommended for abdominal CT in clinical application.
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Objective To evaluate the CT spectral imaging in assessing the therapeutic efficacy of axitinib in rabbit VX2 liver tumors. Methods Thirty-two VX2 liver tumor-bearing rabbits (diameter 1.0 to 2.5 cm) were prospectively and randomly assigned into the study group (axitinib treated group, n=16) or the control group (pseudo-therapy group, n=16). They were treated with axitinib or saline by using the gastric tube respectively. All the rabbits underwent unenhanced, arterial-phase (AP) and portal-phase (PP) contrast enhanced CT examinations by using spectral CT at different time points (baseline, 2, 4, 7, 10 and 14 days after treatment). Tumor size (TS) at each time point was recorded to calculate the percentage change (ΔTS)after treatment relative to baseline. Iodine concentration (IC) of the entire tumor, the peripheral hypervascular region and the center of the tumor were measured and normalized to aorta (NIC) to generate the difference for the NIC (NICD) between a given time and baseline. The tumorΔTS and NICD between the control and treated groups were compared by using Mann-Whitney U test. Serial changes in NICD at different time points were evaluated by using Wilcoxon signed rank test. Correlations between the NICD andΔTS, between NIC and microvessel density (MVD) were analyzed. Results The tumorΔTS after treatment in the control group and study group increased continuously. The tumorΔTS was significantly smaller in the treated group than that in the control group at day 7, 10 and 14. At day 2 , 4 and 10 after treatment, each tumor NICD in the study group was smaller compared with the control group(P0.05).Conclusion CT spectral imaging allows the evaluation and early prediction of tumor response to axitinib in rabbit VX2 liver tumors.
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<p><b>OBJECTIVE</b>To investigate the preoperative assessment value of spectral CT quantitative parameters in lymph node metastasis of gastric cancer.</p><p><b>METHODS</b>From December 2013 to June 2015, clinical and image data of 86 patients with gastric cancer confirmed by gastroscope pathology undergoing preoperative enhanced CT were prospectively collected. Enhanced CT included nonenhanced CT of conventional 120 kVp mode, arterial phase (AP) and venous phase (VP) with GSI mode on Discover GSI CT scanner. The raw data were transferred to ADW4.6 workstation to reconstruct the monochromatic images at 70 keV and iodine-based images in AP and VP with 1.25 mm thickness. The short diameter, long diameter, ratio of short to long diameter, CT attenuation and iodine value of lymph nodes in each phase were measured and recorded. Pathology results were used as golden standard. The spectral CT quantitative parameters of positive and negative lymph nodes were compared by t test and the sensitivity and specificity analyses were performed by ROC curves. This clinical study registration number 81271573.</p><p><b>RESULTS</b>Among these 86 gastric cancer patients (53 male and 33 female), tumors of 28 cases were in upper part, of 12 cases in middle part, of 27 cases in distal part and of 19 cases involved two parts. Thirty-five cases were differentiated type and 51 cases were undifferentiated type. A total of 1 072 lymph nodes were found in operation, of which 412 nodes were positive and 660 were negative. Among 552 lymph nodes found in CT images, 338 nodes were positive and 214 were negative. Compared to negative lymph nodes, short diameter [(9.52±3.58) mm vs. (6.48±2.94) mm, t=4.639, P=0.000], ratio of short to long diameter (0.82±0.14 vs. 0.61±0.08, t=13.514, P=0.000), CT attenuation in precontrast [(20.44±6.77) Hu vs. (16.06±7.14) Hu, t=3.154, P=0.002], CT attenuation in AP[(61.71±11.78) Hu vs. (40.11±10.18) Hu, t=9.588, P=0.000], CT attenuation in VP[(71.34±13.03) Hu vs. (53.81±11.39) Hu, t=7.888, P=0.000], iodine value in AP [(16.17±4.22) 100 μg/cmvs. (8.03±3.10) 100 μg/cm, t=9.781, P=0.000], the iodine value in VP [(20.13±6.04) 100 μg/cmvs. (11.58±4.13) 100 μg/cm, t=10.147, P=0.000] of positive lymph nodes were greater. The long diameter was not significantly different between positive and negative lymph nodes [(11.71±5.63) mm vs. (10.64±3.20) mm, t=1.380, P=0.169]. The area under ROC curve of short diameter, ratio of short to long diameter, CT attenuation in precontrast, AP and VP, iodine value in AP and VP of lymph nodes was 0.600, 0.880, 0.648, 0.832, 0.755, 0.864, 0.835, respectively. Taking the ratio of short to long diameter over 0.72 as diagnosis standard, the sensitivity was 75.6% and the specificity was 93.5%. Taking the CT number in AP over 49.75 Hu, the sensitivity was 66.9% and the specificity was 88.8%. Taking the CT number in VP over 59.80 Hu, the sensitivity was 69.9% and the specificity was 77.6%. Taking the iodine value in AP over 9.65 (100 μg/cm), the sensitivity was 80.4% and the specificity was 82.2%. Taking the iodine value in VP over 15.65 (100 μg/cm), the sensitivity was 69.9% and the specificity was 86.9%. Combinong the ratio of short to long diameter with the iodine value in AP, the sensitivity was 95.2% and the specificity was 76.9%.</p><p><b>CONCLUSIONS</b>The ratio of short to long diameter, the iodine value and CT attenuation in AP and VP of lymph nodes in spectral CT are important criteria to evaluate the metastasis of gastric cancer. Combining the ratio of short to long diameter with the iodine value in AP can obviously improve the sensitivity.</p>
Subject(s)
Female , Humans , Male , Gastroscopy , Iodine Radioisotopes , Lymph Nodes , Diagnostic Imaging , Pathology , Lymphatic Metastasis , Diagnostic Imaging , ROC Curve , Sensitivity and Specificity , Stomach Neoplasms , Diagnostic Imaging , Tomography, X-Ray Computed , MethodsABSTRACT
Objective To investigate the image quality and radiation dose of automatic spectral imaging mode selection and adaptive statistical iterative reconstruction (ASIR) at abdominal CT with low contrast agent dose. Methods One hundred cases with the arterial-phase (AP) and portal venous phase (PVP) contrast-enhanced abdominal CT scanning were analyzed prospectively. Patients were randomly assigned to the study group and control group (n=50 each). In the study group, automatic spectral imaging mode selection and contrast agent dose of 300 mg/kg were used and spectral monochromatic images(40 to 60 keV) were reconstructed using either filtered back-projection (FBP) (group A) or ASIR (group B). In the control group, the fixed tube potential of 120 kVp and contrast agent dose of 450 mg/kg were used with images reconstructed using FBP (group C). Quantitative parameters (image noise and contrast-to-noise ratio of the liver, pancreas, aorta and portal vein) and qualitative visual parameters (overall image quality as graded on a 5-point scale) were compared among the groups by using One-way ANOVA or Kruskal-Wallis H test. Two sample t tests were used compare the radiation dose difference. Results There had no significant difference in CTDIvol[both (12±5) mGy] and DLP[(364±142) mGy·cm versus (377±131) mGy·cm] between the study group and control group(t=-0.408 and-0.428,P>0.05). During the AP and PVP, at the energy level of 40 keV, group B showed higher CNRs than group A and group C, lower image noise[ (29±6) HU in AP, (24±6) HU in PVP] than group A[(43±11) HU, (44±10) HU] but higher image noise than group C[ (18± 4) HU, (18±4) HU], lower overall image quality scores[(3.0±0.2) point, (2.9±0.3) point] than group C[(3.6± 0.4) point , (3.6±0.5) point] but similar scores to group A[(2.9±0.4) point,(2.8±0.4)point]. At the energy level of 50 keV, group B showed higher CNRs than group A but higher than or similar CNRs to group C, lower image noise[ (20±5) HU, (20±4) HU] than group A[(31±8) HU, (31±7) HU] but similar image noise to group C, higher overall image quality scores[(3.6±0.4) point, (3.5±0.4) point]than group A[(3.3±0.3) point,(3.3±0.3) point] but similar scores to group C. At the energy level of 60 keV, group B showed lower image noise[(14±4) HU, (14±3) HU], higher CNRs and overall image quality scores[(3.9±0.4) point,(3.9±0.3) point] than group A[(19 ± 5) and (20 ± 5)HU in image noise, (3.7 ± 0.4) and (3.7 ± 0.3) point in overall image quality scores ]and group C. Except for monochromatic images at 40 keV, the overall image quality scores in group B were all greater than 3 point and met the clinical diagnostic level. Conclusions The radiation dose of CT spectral imaging and conventional 120 kVp CT scan is equivalent with the use of automatic spectral imaging mode selection. By combining ASIR technique, monochromatic images at 50 and 60 keV can improve CNR and reduce contrast agent dose while maintain or improve overall image quality.
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Objective To assess the effects of image fusion of CT spectral monochromatic imaging on image quality in small hepatocellular carcinoma (HCC).Methods Thirty patients with 40 pathologically proven small HCCs (≤3 cm) underwent upper abdominal plain CT and dual-phase enhanced spectral CT scan were analyzed retrospectively.Conventional 140 kVp polychromatic images (group A) and monochromatic images with energy levels from 40 to 140 keV were reconstructed by using spectral imaging viewer.Monochromatic images with highest CNR (group B)and 70 keV images with lowest noise (group C) were fused to generate fused images (group D) with image fusion software.Objective evaluation of 40 HCCs [contrast-to-noise ratio (CNR) of lesion,image noise in HU] and subjective rating score of 30 patients (image noise score,overall image quality score,and lesion conspicuity score) among the four groups were compared by using One-way ANOVA and Kruskal-Wallis H test.Results CNR (1.3±0.6,2.1±0.6,1.5±0.6 and 2.4± 1.3 respectively) and image noise [(20±7),(32±9),(18±3) and (24±6) HU respectively] among group A,B,C and D all had statistical differences (F =5.724 and 13.619,both P values ＜ 0.01).CNR in group D was higher as compared with group A and C (both P values ＜ 0.05),but was similar to group B (P ＞ 0.05).Image noise in group D was lower than group B and higher than group C,but showed no difference from group A (all P values ＞ 0.05).Image noise scores [(3.5±0.5),(3.3±0.4),(3.6±0.5)and(3.5±0.4)point,respectively],overall image quality scores [(3.2 ± 0.4),(3.3 ± 0.3),(3.1 ± 0.3) and (3.7 ± 0.4) point respectively] and lesion conspicuity scores [(3.3 ±0.4),(3.9±0.4),(3.2±0.4) and (3.7 ±0.4) point,respectively] among the four groups all had statistical differences (Z =9.581,37.495 and 43.436,all P values ＜ 0.05).Scores of the four groups were all greater than 3 and met the clinical diagnostic level.Group D was higher than group B in image noise score,higher than the other three groups in overall image quality score,higher than group A in lesion conspicuity score (all P values ＜ 0.05).Conclusion Combined use of CT spectral monochromatic imaging and image fusion can improve overall image quality while maintaining or increasing CNR in small HCC.
ABSTRACT
Objective To investigate the impact of automatic tube voltage selection ( ATVS) and sinogram-affirmed iterative reconstruction ( SAFIRE) on image quality and radiation dose in the arterial phase (AP) and portal venous phase (PVP) abdominal dual-source CT imaging.Methods Abdomen contrast-enhanced computed tomography ( CECTs ) in 70 patients were scanned with dual-source CT.Patients were divided into study group and control group based on the scanning date.In the first 35 patients ( study group) , ATVS mode was applied; in the second 35 patients ( control group ) , the conventional fixed at 120 kVp mode was used.The imaging of the study group was reconstructed with FBP ( protocol A ) or SAFIRE ( protocol B ) respectively; the imaging of the control group was reconstructed with FBP ( protocol C).Image quality scores of the 3 protocols were assessed and compared with Rank-sum test.Analysis of variance was used to compare mean signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image noise among the 3 protocols.Two sample t tests were used to compare the radiation dose difference.Results The effective radiation dose in the study group ( 3.9 ±0.4 ) mSv was much lower than that in the control group (4.9 ±0.4) mSv, dropped by 20.41% (t =2.315, P=0.021).The subjective rating scores in protocol A, B, C in arterial were (3.65 ±0.08), (4.41 ±0.10) and (3.79 ±0.10) point, while the subjective rating scores in venous phase were (3.57 ±0.08), (4.41 ±0.10) and (3.95 ±0.11) point.The differences were statistically significant (Z value were 27.587 and 27.436, P0.05).Conclusion Use of ATVS and SAFIRE could reduce the radiation dose and provide better quality images compared with conventional abdominal CECT and FBP .