Histogram analysis based on intravoxel incoherent motion diffusion-weighted imaging for determining the perineural invasion status of rectal cancer.

Background: Unfortunately, the morphologic magnetic resonance imaging (MRI) is unable to determine perineural invasion (PNI) status. This study applied histogram analysis of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in the assessment of PNI status of rectal cancer (RC). Methods: The retrospective analysis enrolled 175 patients with RC confirmed by postoperative pathology in The First Affiliated Hospital of Shandong First Medical University from January 2019 to December 2021. All patients underwent preoperative rectal MRI. Whole-tumor volume histogram features from IVIM-DWI were extracted using open-source software. Univariate analysis and multivariate logistic regression analysis were used to compare the differences in histogram parameters and clinical features between the PNI-positive group and PNI-negative group. Receiver operating characteristic curve analysis was used to evaluate the diagnostic performance, while the Delong test was used to compare the area under the curve of the models. Results: The interobserver agreement of the histogram features derived from DWI, including apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), water molecular diffusion heterogeneity index (α), and distributed diffusion coefficient (DDC) were good to excellent. A total of eight histogram features including DWI_maximum, DWI_skewness, D_kurtosis, D_minimum, D_skewness, D*_energy, D*_skewness, and f_minimum were significantly different between the PNI-positive and PNI-negative groups in the univariate analysis (P<0.05); among the clinicoradiologic factors, percentage of rectal wall circumference invasion (PCI) was significantly different between the two groups (P<0.05). Multivariate analysis demonstrated that the values of D*_energy, D*_skewness, and f_minimum differed significantly between the PNI-positive patients and PNI-negative patients (P<0.05), with the independent risk factors being D*_skewness [odds ratio (OR) =1.157; 95% confidence interval (CI): 1.050-1.276; P=0.003] and PCI (OR =11.108, 95% CI: 1.767-69.838; P=0.0002). The area under the curve of the model combining the three histogram features and PCI to assess PNI status in RC was 0.807 (95% CI: 0.741-0.863). The results of the Delong test showed that the combined model was significantly different from each single-parameter model (P<0.05). Conclusions: The combined model constructed on the basis of IVIM-DWI histogram features may help to assess the status of RC PNI.

Gastrointestinal bleeding due to obstruction of the superior mesenteric vein.

ABSTRACT: Gastrointestinal bleeding is a common clinical symptom. Finding the underlying cause is the first step for treatment. In a few patients, this can be difficult. The present work reports on the unusual case of a 53-year-old man who presented gastrointestinal bleeding. No bleeding site was found by gastrocolonoscopy or interventional examination, but after multidisciplinary consultation, we discovered that the cause of gastrointestinal bleeding was the obstruction of the upper mesenteric vein.

Development and validation of a nomogram for predicting operating time in laparoscopic anterior resection of rectal cancer.

Aims: The goal of this study is to create and verify a nomogram estimate operating time in rectal cancer (RC) patients based on clinicopathological factors and MRI/CT measurements before surgery. Materials and Methods: The nomogram was developed in a cohort of patients who underwent laparoscopic anterior resection (L-AR) for RC. The clinicopathological and pelvis parameters were collected. Risk factors for a long operating time were determined by univariate and multivariate logistic regression analyses, and a nomogram was established with independent risk factors. The performance of the nomogram was evaluated. An independent cohort of consecutive patients served as the validation dataset. Results: The development group recruited 159 RC patients, while 54 patients were enrolled in the validation group. Independent risk factors identified in multivariate analysis were a distance from the anal verge <5 cm (P = 0.024), the transverse diameter of the pelvic inlet (P < 0.001), mesorectal fat area (P = 0.017), and visceral fat area (P < 0.001). Then, a nomogram was built based on these four independent risk factors. The C-indexes of the nomogram in the development and validation group were 0.886 and 0.855, respectively. And values of AUC were the same with C-indexes in both groups. Besides, the calibration plots showed satisfactory consistency between actual observation and nomogram-predicted probabilities of long operating time. Conclusions: A nomogram for predicting the risk of long operating duration in L-AR of RC was developed. And the nomogram displayed a good prediction effect and can be utilized as a tool for evaluating operating time preoperatively.

Predicting tumor deposits in patients with rectal cancer: Using the models of multiple mathematical parameters derived from diffusion-weighted imaging.

PURPOSE: Using mono-exponential, bi-exponential, and stretched-exponential models of multi-b-value diffusion-weighted imaging (DWI) to predict tumor depositions (TDs) in patients with rectal cancer (RC). MATERIAL AND METHODS: This retrospective study, between January 2018 and November 2021, enrolled 30 TDs-positive and 38 TDs-negative of patients with rectal cancer. The mathematical parameters including ADC from mono-exponential model, D, D* and f from bi-exponential model, and DDC and α from stretched-exponential model, clinical factors (such as age, gender, pathological stage, etc.) and image features (such as length, thickness, location, etc.) from tumor characteristics were obtained to identify the two groups of patients. The results were evaluated by the receiver operating characteristic curve (ROC) analysis and area under the ROC curve (AUC). Multivariate binary logistic regression analysis was conducted to determine the independent risk factors. RESULTS: The D* and α values, pt. stage, tumor location, mesorecta fascia (MRF) / peritoneum status and percentage of rectal wall circumference invaded (PCI) were significantly different between the TDs-positive and TDs-negative groups (P < 0.001, P < 0.001, P = 0.029, P = 0.008, P < 0.001 and P = 0.002, respectively), with the AUC were 0.838, 0.901, 0.618, 0.698 0.694 and 0.758, respectively. The D* and α values were proved to be independent risk factors after multivariate binary logistic regression analysis (p = 0.022 and 0.004, respectively). The AUC of the model consisting of the D* and α values was 0.913 (95 % CI 0.820 âˆ¼ 0.968).The combined model constructed by D*, α and tumor location demonstrated superior diagnostic performance, with the AUC, sensitivity, specificity, and accuracy of 0.947 (95 % confidence interval, CI, 0.865-0.987), 0.900, 0.868 and 0.853, respectively. CONCLUSION: Multiple mathematical parameters can be used as preoperative auxiliary diagnostic tools to predict TDs of RC. The combined model constructed by D*, α and tumor location show better diagnostic performance for TDs.

Development and validation of a high-resolution T2WI-based radiomic signature for the diagnosis of lymph node status within the mesorectum in rectal cancer.

Purpose: The aim of this study was to explore the feasibility of a high-resolution T2-weighted imaging (HR-T2WI)-based radiomics prediction model for diagnosing metastatic lymph nodes (LNs) within the mesorectum in rectal cancer. Method: A total of 604 LNs (306 metastatic and 298 non-metastatic) from 166 patients were obtained. All patients underwent HR-T2WI examination and total mesorectal excision (TME) surgery. Four kinds of segmentation methods were used to select region of interest (ROI), including method 1 along the border of LNs; method 2 along the expanded border of LNs with an additional 2-3 mm; method 3 covering the border of LNs only; and method 4, a circle region only within LNs. A total of 1,409 features were extracted for each method. Variance threshold method, Select K Best, and Lasso algorithm were used to reduce the dimension. All LNs were divided into training and test sets. Fivefold cross-validation was used to build the logistic model, which was evaluated by the receiver operating characteristic (ROC) with four indicators, including area under the curve (AUC), accuracy (ACC), sensitivity (SE), and specificity (SP). Three radiologists with different working experience in diagnosing rectal diseases assessed LN metastasis respectively. The diagnostic efficiencies with each of four segmentation methods and three radiologists were compared to each other. Results: For the test set, the AUCs of four segmentation methods were 0.820, 0.799, 0.764, and 0.741; the ACCs were 0.725, 0.704, 0.709, and 0.670; the SEs were 0.756, 0.634, 0.700, and 0.589; and the SPs were 0.696, 0.772, 0.717, and 0.750, respectively. There was no statistically significant difference in AUC between the four methods (p > 0.05). Method 1 had the highest values of AUC, ACC, and SE. For three radiologists, the overall diagnostic efficiency was moderate. The corresponding AUCs were 0.604, 0.634, and 0.671; the ACCs were 0.601, 0.632, and 0.667; the SEs were 0.366, 0.552, and 0.392; and the SPs were 0.842, 0.715, and 0.950, respectively. Conclusions: The proposed HR-T2WI-based radiomic signature exhibited a robust performance on predicting mesorectal LN status and could potentially be used for clinicians in order to determine the status of metastatic LNs in rectal cancer patients.

A comprehensive investigation of zeolite-rich tuff functionalized with 3-mercaptopropionic acid intercalated green rust for the efficient removal of HgII and CrVI in a binary system.

In this study, the 3-mercaptopropionic acid (MA) was chosen to achieve the anionic intercalation into the green rust (GR) materials (MA-GR). The zeolite-rich tuff functionalized with the MA-intercalated GR (MA-GR-tuff) was subsequently synthesized and used to remove both HgII cations and CrVI anions in a binary system. MA-GR-tuff showed the best adsorption capacities to both HgII and CrVI among the adsorbent materials. The optimal combination of parameters was determined as the molar ratio of FeII to FeIII of 3.5, the molar ratio of OH- to the total iron of 3.75, the molar ratio of MA to the total iron of 2.5, and the mass ratio of the total iron to the tuff of 1.25. The pseudo-first-order kinetic model was appropriate in describing the kinetic sorption of CrVI by MA-GR-tuff. Both the pseudo-first-order kinetic model and Elovich were suitable for explaining HgII sorption. The maximum monolayer adsorption capacities of MA-GR-tuff towards CrVI and HgII were 185.19 mg/g and 72.99 mg/g, respectively. More flocs and plumes were formed in the MA-GR while the intercalation and more pores and crevices of different sizes were found in the MA-GR-tuff. Sulfhydryl complexation and the molecular sieve of tuff obviously both played a role in influencing the adsorption process. This study directly overcomes the drawback brought by the natural tuff to the treatment of a cationic-and-anionic binary system and supplies a new kind of tuff-based adsorbent for the potential use for the remediation of HM-contaminated wastewater.

Intravoxel incoherent motion DWI with different mathematical models in predicting rectal adenoma with and without canceration.

PURPOSE: To evaluate the clinical value of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) with mono-exponential (ME), bi-exponential (BE), and stretched-exponential (SE) models for predicting rectal adenomas with canceration. MATERIAL AND METHODS: Sixty patients with postoperative pathology-confirmed rectal adenoma (n = 31) and adenoma with canceration (n = 29) were enrolled and underwent IVIM-DWI scanning. The ME-derived apparent diffusion coefficient (ADC), BE-derived true diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), SE-derived distributed diffusion coefficient (DDC), and water molecular diffusion heterogeneity index (α) were measured. The differences in each parameter between adenoma and canceration were compared. Multivariate binary logistic regression analysis was used to establish models for predicting rectal adenomas with canceration. Receiver operating characteristic curve analysis was applied to evaluate diagnostic performances of each model in terms of sensitivity, specificity, accuracy, and area under the curve (AUC). RESULTS: The AUCs of ADC, D, D*, f, DDC and α were 0.851 (95 % confidence interval, CI, 0.735-0.930), 0.895 (95 % CI, 0.789-0.960), 0.720 (95 % CI, 0.589-0.828), 0.791 (95 % CI, 0.667-0.886), 0.841 (95 % CI, 0.724-0.923) and 0.738 (95 % CI, 0.608-0.834), respectively. The AUCs of BE and SE models were 0.927 (95 % CI, 0.829-0.978) and 0.874 (95 % CI, 0.763-0.946), respectively. The AUC, sensitivity, specificity, and accuracy of the derived four values (ADC, D, f, and DDC) from the combination of three models were 0.950, 96.6 % (95 % CI, 95.3-97.6 %), 80.6 % (95 % CI, 78.0-82.9 %), and 88.3 % (95 % CI, 86.2-90.2 %), respectively. CONCLUSION: ADC can easily and effectively predict rectal adenomas with canceration. The BE model has a better combination of sensitivity and specificity for the diagnosis of rectal adenoma canceration.

Synergistic effect of ultrasonication and sulfate radical on recovering cobalt and lithium from the spent lithium-ion battery.

Ultrasonication has been mechanically applied widely in the recycling of spent lithium-ion (SLI) batteries while its influence on chemical pathways has barely been reported. In this study, ultrasonication and sulfate radicals were used in a coupling system to obtain efficient recoveries of Co and Li from SLI batteries. The synergistic effect of ultrasonication and sulfate radicals on recycling was quantitatively analysed by significance analysis and surface responses in a central composite design. The employment of persulfate significantly affected the whole recycling process during the sonication. Factors including acoustic time, operating powers, and temperature all had a significant effect on the recoveries of Co and Li. The maximum recovery efficiencies of Co and Li of 97.33% and 99.25%, respectively, and the minimum loss rate of Al of 4.13% were simultaneously obtained by the fitting predictor. The optimal combination of factors for the sonication system included an acoustic time (min) of 5.5, an operating power (W) of 168, a temperature (°C) of 86, and a ratio of cathode foil to S-solution (mg/mL) of 1:60. A moiety of cathode active material was directly separated from the aluminium collector by sulfate radical-related reactions. Co and Li cations dissolved from LiCoO2 by carbon dioxide radicals were reprecipitated by excess oxalate. The research demonstrated the positively synergistic influence caused by ultrasonication and sulfate radicals on achieving efficient recoveries of Co and Li from SLI batteries, explicitly expanding the technical choices for the recycling procedure.

Non-thermal plasma irradiated polyaluminum chloride for the heterogeneous adsorption enhancement of Cs+ and Sr2+ in a binary system.

The natural ecosystem will continually deteriorate for decades by the leakage of Cs and Sr isotopes. The exploration of the new materials or techniques for the efficient treatment of radioactive wastewater is critically important. In this study, a dielectric barrier discharge (DBD) configuration was constructed to operate the non-thermal plasma (NTP). The NTP was incorporated into the synthesis of polyaluminum chloride (PAC) in two different procedures to intensify the synthesis of PAC (NTP-PAC) and enhance the further removal of Cs and Sr from wastewater. The employment of NTP in two procedures both had significantly changed the physicochemical characteristics of PAC materials, which facilitated the further adsorption application of NTP-PAC on the treatment of Cs+ and Sr2+. Different molecular, morphological, and adsorption characteristics were confirmed to the NTP-PAC materials. The heterogeneous adsorption of the NTP-PAC can be appropriately fitted by both the pseudo-first-order kinetic model and the Elovich model. Both physisorption and chemisorption reaction mechanisms were ensured for the heterogeneous adsorption of the NTP-PAC material towards Cs+ and Sr2+, which guaranteed the excellent adsorption performance of NTP-PAC materials compared to PAC. The electron collisions caused by NTP with alum pulp created highly reactive growth precursors and intensified the nucleation and hydrolysis polymerization of PAC. The employment of NTP explicitly broadens the reaction pathways between PAC and cationic contaminants in the aqueous environment, which expands the application area of PAC materials in environmental sustainability.

Multiparametric MRI-based machine learning models for preoperatively predicting rectal adenoma with canceration.

OBJECTIVES: To propose multiparametric MRI-based machine learning models and assess their ability to preoperatively predict rectal adenoma with canceration. MATERIALS AND METHODS: A total of 53 patients with postoperative pathology confirming rectal adenoma (n = 29) and adenoma with canceration (n = 24) were enrolled in this retrospective study. All patients were divided into a training cohort (n = 42) and a test cohort (n = 11). All patients underwent preoperative pelvic MR examination, including high-resolution T2-weighted imaging (HR-T2WI) and diffusion-weighted imaging (DWI). A total of 1396 radiomics features were extracted from the HR-T2WI and DWI sequences, respectively. The least absolute shrinkage and selection operator (LASSO) was utilized for feature selection from the radiomics feature sets from the HR-T2WI and DWI sequences and from the combined feature set with 2792 radiomics features incorporating two sequences. Five-fold cross-validation and two machine learning algorithms (logistic regression, LR; support vector machine, SVM) were utilized for model construction in the training cohort. The diagnostic performance of the models was evaluated by sensitivity, specificity and area under the curve (AUC) and compared with the Delong's test. RESULTS: Ten, 8, and 25 optimal features were selected from 1396 HR-T2WI, 1396 DWI and 2792 combined features, respectively. Three group models were constructed using the selected features from HR-T2WI (ModelT2), DWI (ModelDWI) and the two sequences combined (Modelcombined). Modelcombined showed better prediction performance than ModelT2 and ModelDWI. In Modelcombined, there was no significant difference between the LR and SVM algorithms (p = 0.4795), with AUCs in the test cohort of 0.867 and 0.900, respectively. CONCLUSIONS: Multiparametric MRI-based machine learning models have the potential to predict rectal adenoma with canceration. Compared with ModelT2 and ModelDWI, Modelcombined showed the best performance. Moreover, both LR and SVM have equal excellent performance for model construction.

The Effect of Rectal Distention on the Intravoxel Incoherent Motion Parameters: Using Sonography Transmission Gel.

OBJECTIVE: To compare the intravoxel incoherent motion (IVIM) parameters of rectal tumors before and after lumen distension obtained with sonography transmission gel. METHODS: Twenty-five patients were enrolled. The multiple b values of IVIM including 0, 20, 50, 100, 150, 200, 400, 600, 800, 1000, 1500, and 2000 s/mm. Two blinded readers have drawn the region of interests and calculated the D, D*, and f values. Interobserver variability between the 2 readers was measured by intraclass correlation coefficients and Altman-Bland plots. The intergroup differences of the average values were compared with the paired sample t test. RESULTS: After distention, the interrater agreement of the D* value increased obviously (from 0.547 to 0.692) and that of the D and f values increased slightly (from 0.731 and 0.618 to 0.807 and 0.666). The difference in the D value had statistical significance (P = 0.0043). CONCLUSIONS: Intraluminal distension can increase the repeatability of IVIM parameters and the value of IVIM.

Automatic spectral imaging protocol and iterative reconstruction for radiation dose reduction in typical hepatic hemangioma computed tomography with reduced iodine load: a preliminary study.

OBJECTIVE: To evaluate the effect of automatic spectral imaging protocol selection (ASIS) and adaptive statistical iterative reconstruction (ASiR) technique in the reduction of radiation and contrast medium dose in typical hepatic hemangioma (HH) dual energy spectral CT (DEsCT). METHODS: 62 patients with suspected HH were randomly divided into two groups equally: Group A, conventional 120-kVp CT with standard iodine load; Group B, DEsCT with ASIS technique and reduced iodine load, two sets of monochromatic spectral images were reconstructed: 69 keV level with 30% ASiR (Group B1) and 52 keV level with 50% ASiR (Group B2). The radiation and total iodine dose, quantitative analysis (standard deviation value, contrast-to-noise and contrast enhancement ratio) and qualitative analysis were evaluated. RESULTS: No difference was observed in the standard deviation values, subjective image noise, and the diagnostic acceptability score among the three groups (p > 0.05). Contrast to noise [Group B2  vs A, B1 in arterial phase (AP): 19.51 ± 6.29 vs 15.77 ± 5.93, 11.46 ± 2.84; Group B2  vs A, B1 in portal venous phase (PVP): 9.96 ± 2.18 vs 8.19 ± 3.04, 6.01 ± 1.82], contrast enhancement ratio (Group B2  vs A, B1 in AP: 6.88 ± 2.01 vs 5.47 ± 2.01, 4.15 ± 1.28; Group B2  vs A, B1 in PVP: 5.58 ± 1.02 vs 4.54 ± 1.13, 3.49 ± 0.83), and the lesion conspicuity score (Group B2  vs A, B1 in AP: 3.93 ± 0.26 vs 3.45 ± 0.51, 3.10 ± 0.49; Group B2  vs A, B1 in PVP: 3.90 ± 0.31 vs 3.48 ± 0.57, 3.14 ± 0.44) for Group B2 were higher than those in Group A and B1 (p < 0.05). Compared to Group A, the radiation dose and total iodine dose in Group B were reduced by 30 and 41%, respectively (radiation dose in Group B vs A: 5.53 ± 1.59 vs 7.91± 2.71 mSv; iodine dose in Group B vs A: 18.85 ± 2.88 vs 31.78±3.89 ml; p < 0.05). CONCLUSION: DEsCT with ASIS and ASiR technique can reduce the radiation dose without image quality degradation as compared to the conventional 120-kVp CT. The monochromatic spectral images at 52 keV level with 50% ASiR allows the reduction in total iodine dose without deteriorating diagnostic performance. Advances in knowledge: ASIS combined with ASiR technique, by using monochromatic spectral images at 52 keV level, represents a feasible imaging protocol to reduce the radiation and total iodine dose in assessment of typical HH.

Comparison of Echocardiography and 64-Multislice Spiral Computed Tomography for the Diagnosis of Pediatric Congenital Heart Disease.

BACKGROUND The goals of this study were: to compare echocardiogram and 64-multislice spiral computed tomography (64-MSCT) in diagnosing pediatric congenital heart disease; to determine the significance of ECHO for diagnosing congenital heart disease; and to identify the appropriate diagnosis for congenital heart disease through combined use of 64-MSCT and ECHO. MATERIAL AND METHODS Thirty patients underwent both ECHO and 64-MSCT diagnoses before their surgeries. Imaging from ECHO and 64-MSCT were analyzed by 4 specialists. The diagnostic accuracy and kappa value of ECHO and 64-MSCT were evaluated based on the operation results. The accuracy of the 2 methods was evaluated using the McNemar χ² test. RESULTS We confirmed 138 malformations in 30 children by surgery. The diagnostic accuracy of ECHO and 64-MSCT was 98.40% and 96.20%, respectively, with a significant difference between the 2 results (χ²=6.404, P=0.011). We compared prognosis accuracy and uniformity on 3 types of congenital heart disease (cardiac malformation, heart-large vascular connecting malformation, and large vascular malformation): 56 cardiac malformations were confirmed by surgery, in which the diagnostic accuracy of ECHO and 64-MSCT was 99.50% and 94.80%, respectively. (χ²=8.578, P=0.034); 31 heart-large vascular connecting malformations were confirmed by surgery, in which the diagnostic accuracy of ECHO and 64-MSCT was 99.00% and 95.42% (χ²=6.779, P=0.009); and 51 vascular malformations were confirmed, in which the diagnostic accuracy of ECHO and 64-MSCT was 96.30% and 98.30% (χ²=1.806, P=0.179). CONCLUSIONS ECHO is more effective than 64-MSCT in preoperative diagnosis of congenital heart disease, especially for children.

A retrospective study of dual-energy CT for clinical detecting of metastatic cervical lymph nodes in laryngeal and hypopharyngeal squamous cell carcinoma.

CONCLUSION: After the reconstruction of imaging in dual-energy CT gemstone spectral imaging, the ratio of the two slopes curves, the target lymph node and primary lesion, respectively, might contribute to the clinical diagnosis of cervical lymph nodes in laryngeal and hypopharyngeal squamous carcinoma. OBJECTIVE: To investigate the value of the dual-energy CT gemstone spectral imaging for clinical detecting of metastatic cervical lymph nodes in laryngeal and hypopharyngeal squamous carcinoma. METHODS: Forty-seven cases who were suffering from laryngeal or hypopharyngeal squamous carcinoma and had complete clinical and pathological data were included, and 79 cervical lymph nodes were studied retrospectively (including 31 metastatic nodes and 48 non-metastatic nodes). Contrast-enhanced energy spectral imaging and reconstruction were performed. After the reconstruction, the slope of the curve in the target lymph node and the lesion were calculated. The ratio of the two slopes was studied. The pathological data of cervical lymph node and primary lesion were also collected. RESULTS: The ratios were 1.20 ± 0.09 and 0.82 ± 0.12 in metastatic and non-metastatic lymph nodes, respectively. The difference was statistically significant (p < 0.05). The ratio was positively correlated to the stasis of lymph nodes only, rather than their morphological appearance, the pathological classification, or the individual difference (p < 0.05).

Preliminary study of dose reduction and image quality of adult pelvic low-dose CT scan with adaptive statistical iterative reconstruction.

BACKGROUND: Because pelvic computed tomography (CT) is widely used in clinical practice, there are increasing concerns regarding the associated risks of radiation-induced cancer. Therefore, the capability to reduce the CT radiation dose without compromising image quality is desirable. PURPOSE: To assess the radiation dose and image quality of adult pelvic CT using both a routine dose and low radiation dose with filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR). MATERIAL AND METHODS: Forty-five patients underwent both routine-dose CT with FBP reconstruction and low-dose CT with FBP and 50% ASIR blending ratio (ASIR50) reconstruction, respectively. Three different groups of image data were compared for subjective and objective image quality. CT dose index volume (CTDIvol), dose-length product (DLP), and effective dose (ED) were recorded. RESULTS: The resulting CTDIvol, DLP, and ED following low-dose pelvic CT were 10.80 ± 6.0 mGy, 265.0 ± 55.0 mGy.Cm, and 3.97 ± 0.82 mSv, respectively. When compared with the values obtained following routine-dose pelvic CT, the low-dose pelvic CT values decreased by 62%, 55%, and 56%, respectively (P < 0.001). The results following evaluation of subjective and objective image quality revealed that there was no significant difference (P > 0.05) between routine-dose CT with FBP, and low-dose CT with ASIR50. However, significant differences were detected between low-dose CT with FBP, routine-dose CT with FBP, and low-dose CT with ASIR50 (P < 0.01). CONCLUSION: The application of low-dose pelvic CT with ASIR50 could dramatically reduce the radiation dose and substantially improve image quality.

Spectral CT imaging of laryngeal and hypopharyngeal squamous cell carcinoma: evaluation of image quality and status of lymph nodes.

PURPOSE: The purpose of this study was to evaluate image quality and status of lymph nodes in laryngeal and hypopharyngeal squamous cell carcinoma (SCC) patients using spectral CT imaging. MATERIALS AND METHODS: Thirty-eight patients with laryngeal and hypopharyngeal SCCs were scanned with spectral CT mode in venous phase. The conventional 140-kVp polychromatic images and one hundred and one sets of monochromatic images were generated ranging from 40 keV to 140 keV. The mean optimal keV was calculated on the monochromatic images. The image quality of the mean optimal keV monochromatic images and polychromatic images was compared with two different methods including a quantitative analysis method and a qualitative analysis method. The HU curve slope (λHU) in the target lymph nodes and the primary lesion was calculated respectively. The ratio of λHU was studied between metastatic and non-metastatic lymph nodes group. RESULTS: A total of 38 primary lesions were included. The mean optimal keV was obtained at 55 ± 1.77 keV on the monochromatic images. The image quality evaluated by two different methods including a quantitative analysis method and a qualitative analysis method was obviously increased on monochromatic images than polychromatic images (p<0.05). The ratio of λHU between metastatic and non-metastatic lymph nodes was significantly different in the venous phase images (p<0.05). CONCLUSION: The monochromatic images obtained with spectral CT can be used to improve the image quality of laryngeal and hypopharyngeal SCC and the N-staging accuracy. The quantitative ratio of λHU may be helpful for differentiating between metastatic and non-metastatic cervical lymph nodes.