Conventional Computed Tomography Imaging Research Articles

Improving the diagnosis of common parotid tumors via the combination of CT image biomarkers and clinical parameters

BackgroundOur study aims to develop and validate diagnostic models of the common parotid tumors based on whole-volume CT textural image biomarkers (IBMs) in combination with clinical parameters at a single institution.MethodsThe study cohort was composed of 51 pleomorphic adenoma (PA) patients and 42 Warthin tumor (WT) patients. Clinical parameters and conventional image features were scored retrospectively and textural IBMs were extracted from CT images of arterial phase. Independent-samples t test or Chi-square test was used for evaluating the significance of the difference among clinical parameters, conventional CT image features, and textural IBMs. The diagnostic performance of univariate model and multivariate model was evaluated via receiver operating characteristic (ROC) curve and area under ROC curve (AUC).ResultsSignificant differences were found in clinical parameters (age, gender, disease duration, smoking), conventional image features (site, maximum diameter, time-density curve, peripheral vessels sign) and textural IBMs (mean, uniformity, energy, entropy) between PA group and WT group (P<0.05). ROC analysis showed that clinical parameter (age) and quantitative textural IBMs (mean, energy, entropy) were able to categorize the patients into PA group and WT group, with the AUC of 0.784, 0.902, 0.910, 0.805, respectively. When IBMs were added in clinical model, the multivariate models including age-mean and age-energy performed significantly better than the univariate models with the improved AUC of 0.940, 0.944, respectively (P<0.001).ConclusionsBoth clinical parameter and CT textural IBMs can be used for the preoperative, noninvasive diagnosis of parotid PA and WT. The diagnostic performance of textural IBM model was obviously better than that of clinical model and conventional image model in this study. While the multivariate model consisted of clinical parameter and textural IBM had the optimal diagnostic performance, which would contribute to the better selection of individualized surgery program.

Spectral CT imaging method based on blind separation of polychromatic projections with Poisson prior.

The linear reconstruction of narrow-energy-width projections can suppress hardening artifacts in conventional computed tomography (CT). We develop a spectral CT blind separation algorithm for obtaining narrow-energy-width projections under a blind scenario where the incident spectra are unknown. The algorithm relies on an X-ray multispectral forward model. Based on the Poisson statistical properties of measurements, a constrained optimization problem is established and solved by a block coordinate descent algorithm that alternates between nonnegative matrix factorization and Gauss-Newton algorithm. Experiments indicate that the decomposed projections conform to the characteristics of narrow-energy-width projections. The new algorithm improves the accuracy of obtaining narrow-energy-width projections.

Reducing 4D CT imaging artifacts at the source: first experimental results from the respiratory adaptive computed tomography (REACT) system

Breathing variations during 4D CT imaging often manifest as geometric irregularities known as respiratory-induced image artifacts and ultimately effect radiotherapy treatment efficacy. To reduce such image artifacts we developed Respiratory Adaptive Computed Tomography (REACT) to trigger CT acquisition during periods of regular breathing. For the first time, we integrate REACT with clinical hardware and hypothesize that REACT will reduce respiratory-induced image artifacts ≥ 4 mm compared to conventional 4D CT.4D image sets were acquired using REACT and conventional 4D CT on a Siemens Somatom scanner. Scans were taken for 13 respiratory traces (12 patients) that were reproduced on a lung-motion phantom. Motion was observed by the Varian RPM system and sent to the REACT software where breathing irregularity was evaluated in real-time and used to trigger the imaging beam. REACT and conventional 4D CT images were compared to a ground truth static-phantom image and compared for absolute geometric differences within the region-of-interest. Breathing irregularity during imaging was retrospectively assessed using the root-mean-square error of the RPM measured respiratory signal during beam on (RMSE_Beam_on) for each phase of the respiratory cycle.REACT significantly reduced the average frequency of respiratory-induced image artifacts ≥ 4 mm by 70% for the tumor (p = 0.003) and 76% for the lung (p = 0.0002) compared to conventional 4D CT. Volume reductions of 10% to 6% of the tumor and 2% to 1% of the lung compared to conventional 4D CT were seen. Breathing irregularity during imaging (RMSE_Beam_on) was significantly reduced by 27% (p = 0.013) using the REACT method.For the first time, REACT was successfully integrated with clinical hardware. Our findings support the hypothesis that REACT significantly reduced respiratory-induced image artifacts compared to conventional 4D CT. These experimental results provide compelling evidence for further REACT investigation, potentially providing clearer images for clinical use.

Dual-energy CT perfusion imaging for differentiating WHO subtypes of thymic epithelial tumors

To evaluate the role of conventional contrast-enhanced CT (CECT) imaging and dual-energy spectral CT (DECT) perfusion imaging in differentiating the WHO histological subtypes of thymic epithelial tumours (TETs). Eighty-eight patients with TETs who underwent DECT perfusion scans (n = 51) and conventional CT enhancement scans (n = 37) using a GE Discovery CT750 HD scanner were enrolled in this study. The mean maximal contrast-enhanced range (mean CEmax) and the perfusion and spectral parameters of the lesions were analysed. Among the six WHO subtypes (Type A, AB, B1, B2, and B3 thymoma and thymic carcinoma), the mean CEmax values and most of the perfusion and spectral parameter values of Type A and Type AB were significantly higher than those of the other subtypes (all P < 0.05), and there was no difference among Type B1, B2 and B3 (all P > 0.05). The mean CEmax value was not different between Type B (including Type B1, B2, and B3) and thymic carcinoma (P = 1.000). The PS, IC, NIC and λHU values in the optimal venous phase of thymic carcinoma were higher than those of Type B (all P < 0.05). The parameters of conventional CECT imaging and DECT perfusion imaging can help identify the subtype of TETs, especially those of DECT perfusion imaging in type B thymomas and thymic carcinomas.

Bone marrow edema around the hip in non-traumatic pain: dual-energy CT vs MRI.

To evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) in identifying bone marrow edema (BME) around the hip joint in non-traumatic patients. This prospective IRB-approved study was conducted between January 2019 and October 2019 and included 59 consecutive patients (18 males, 41 females; mean age 61.5years, range 32-82) who were assessed by DECT and magnetic resonance imaging (MRI) within a 5-day period. Diagnostic accuracy values for diagnosing BME on a per-patient and on a per-partition-basis analysis were calculated for DECT images by two readers (R1 and R2, with 15 and 10years of experience, respectively), using MRI as reference for diagnosis. Inter-observer agreements were calculated with k-statistics. A p value of < 0.05 was considered as statistically significant. MRI depicted BME in 44/59 patients (74.58%), with the involvement of 83/708 (11.72%) partitions. The sensitivity, specificity, and accuracy of R1 and R2 were 95.45% (42/44), 86.67% (13/15), and 93.22% (55/59) for R1, and 86.36% (38/44), 80.00% (12/15), and 84.75% (50/59) for R2. For both readers, the BME detection rate was higher in patients with severe edema (100%) in comparison to patients with mild edema (91.30% and 73.91%). In the partition-basis analysis, sensitivity, specificity, and accuracy ranges were 33.3 to 100%, 91.84 to 100%, and 88.14 to 100%, respectively. The inter-observer agreement for patients' analysis was substantial (k = 0.7065), whereas for partition analysis ranged from fair (k = 0.2976) to near-perfect (k = 1.000). DECT can accurately identify BME around the hip joint, in comparison to MRI. • DECT can accurately identify bone marrow edema around the hip joint in a cohort of non-traumatic patients. • The detection of bone marrow edema by means of DECT may help the radiologist to identify associated findings, including avascular necrosis of the femoral head and insufficiency or stress fractures. • In cases of patients suffering from groin pain with bone marrow edema identified by DECT, the concurrent reading of high-resolution conventional CT images may increase the confidence of diagnosis and/or reduce the reading time.

Simultaneous MRI water-fat separation and quantitative susceptibility mapping of carotid artery plaque pre- and post-ultrasmall superparamagnetic iron oxide-uptake.

Imaging carotid artery plaques to identify features of vulnerability typically requires a multicontrast MRI protocol. The identification of regions of inflammation with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles requires separate pre- and postcontrast scans. We propose a method of joint water-fat separation and quantitative susceptibility mapping (QSM) to aid classification of atherosclerotic plaques and offer a positive contrast mechanism in USPIO-imaging. Ten healthy volunteers (3 women and 7 men; aged, 30.7 ± 10.7 years) were imaged at 1.5T to develop an acquisition and postprocessing protocol. Five patients (1 woman and 4 men; mean age, 71 ± 7.5 years) with moderate to severe luminal stenosis were imaged pre- and postadministration of a USPIO contrast agent. We used a multiecho gradient echo acquisition to perform water/fat separation and subsequently QSM. The results were compared with a conventional multicontrast MRI protocol, CT images, and histopathology data. In the volunteer scans, a multiecho gradient echo acquisition with bipolar readout gradients demonstrated to be a reliable acquisition methodology to produce high-quality susceptibility maps in conjunction with the proposed postprocessing methodology. In the patient study, water/fat separation provided a tool to identify lipid-rich necrotic cores and QSM provided a qualitative and quantitative evaluation of plaque features and positive contrast when evaluating USPIO uptake. Plaque calcification could be identified by strong diamagnetism (-1.27 ± 0.71 ppm), while USPIO uptake demonstrated a strong paramagnetism (1.32 ± 0.61 ppm). QSM was able to identify multiple plaque features in a single acquisition, providing positive contrast for plaques demonstrating USPIO uptake and negative contrast for calcification.

Enhancement of soft-tissue contrast in cone-beam CT using an anti-scatter grid with a sparse sampling approach

PurposeAnti-scatter grids suppress the scatter substantially thus improving image contrast in radiography. However, its active use in cone-beam CT for the purpose of improving contrast-to-noise ratio (CNR) has not been successful mainly due to the increased noise related to Poisson statistics of photons. This paper proposes a sparse-view scanning approach to address the above issue. MethodCompared to the conventional cone-beam CT imaging framework, the proposed method reduces the number of projections and increases exposure in each projection to enhance image quality without an additional cost of radiation dose to patients. For image reconstruction from sparse-view data, an adaptive-steepest-descent projection-onto-convex-sets (ASD POCS) algorithm regularized by total-variation (TV) minimization was adopted. Contrast and CNR with various scattering conditions were evaluated in projection domain by a simulation study using GATE. Then we evaluated contrast, resolution, and image uniformity in CT image domain with Catphan phantom. A head phantom with soft-tissue structures was also employed for demonstrating a realistic application. A virtual grid-based estimation and reduction of scatter has also been implemented for comparison with the real anti-scatter grid. ResultsIn the projection domain evaluation, contrast and CNR enhancement was observed when using an anti-scatter grid compared to the virtual grid. In the CT image domain, the proposed method produced substantially higher contrast and CNR of the low-contrast structures with much improved image uniformity. ConclusionWe have shown that the proposed method can provide high-quality CBCT images particularly with an increased contrast of soft-tissue at a neutral dose for image-guidance.

Metal artifacts from sternal wires: evaluation of virtual monoenergetic images from spectral-detector CT for artifact reduction

PurposeIn chest imaging, sternal wires can cause metal artifacts that hamper depiction of surrounding soft tissue and bone. This study investigated if these artifacts may be reduced by means of virtual monoenergetic images (VMI) obtained from a novel detector-based spectral CT scanner (SDCT) in comparison to conventional CT images (CI). Materials and methods30 patients with clinically indicated SDCT scans of the chest exhibiting artifacts due to sternal wires were included in this IRB-approved study. CI and VMI (40–200 keV, 10 keV increment) were reconstructed. Quantitative image analysis was conducted by ROI-based measurement of attenuation (HU) and standard deviation within the most pronounced hypo- and hyperdense artifacts. Visually, artifact reduction and diagnostic assessment of surrounding soft tissue as well as sternal bone were independently rated by two radiologists on 5-point Likert-scales. ResultsIn comparison to CI, high-keV VMI showed an effective reduction of hypo- and hyperattenuating parasternal artifacts, as corrected HU-values approximated their true expected values (hypodense: CI −66.2 ± 70.8; VMI200keV 2.4 ± 29.2; hyperdense: CI 156.7 ± 70.8HU; VMI200keV 76.9 ± 45.4, both p < 0.05). In addition, image noise was significantly lower in high-keV VMI compared to CI. Subjective analysis confirmed that VMI of ≥100 keV significantly reduced artifacts and improved diagnostic assessment of surrounding soft tissue and bone. Interrater-agreement was excellent (intraclass-correlation-coefficient = 0.83). ConclusionsHigh-keV VMI yielded a significant reduction of artifacts from sternal wires and improved assessment of surrounding structures.

Visual enhancement of Cone-beam CT by use of CycleGAN.

Cone-beam computed tomography (CBCT) offers advantages over conventional fan-beam CT in that it requires a shorter time and less exposure to obtain images. However, CBCT images suffer from low soft-tissue contrast, noise, and artifacts compared to conventional fan-beam CT images. Therefore, it is essential to improve the image quality of CBCT. In this paper, we propose a synthetic approach to translate CBCT images with deep neural networks. Our method requires only unpaired and unaligned CBCT images and planning fan-beam CT (PlanCT) images for training. The CBCT images and PlanCT images may be obtained from other patients as long as they are acquired with the same scanner settings. Once trained, three-dimensionally reconstructed CBCT images can be directly translated into high-quality PlanCT-like images. We demonstrate the effectiveness of our method with images obtained from 20 prostate patients, and provide a statistical and visual comparison. The image quality of the translated images shows substantial improvement in voxel values, spatial uniformity, and artifact suppression compared to those of the original CBCT. The anatomical structures of the original CBCT images were also well preserved in the translated images. Our method produces visually PlanCT-like images from CBCT images while preserving anatomical structures.

Usefulness of Virtual Monochromatic Dual-Layer Computed Tomographic Imaging for Breast Carcinoma.

This study aimed to evaluate virtual monochromatic images (VMIs) obtained using dual-layer dual-energy computed tomography (CT) for breast carcinoma. We retrospectively enrolled 28 patients with breast cancer who were pathologically diagnosed using dual-layer dual-energy CT. Virtual monochromatic images (40-200 keV) were generated. We compared CT number, image noise, contrast, and contrast-to-noise ratio (CNR) between VMIs with the highest CNR and conventional CT images. We performed qualitative image analysis between VMIs at optimized energy and conventional CT images. Image noise of VMIs was not significantly different from that of the conventional CT images. As the x-ray energy decreased, CNR increased. The 40-keV VMIs were highest CNR and higher than that of the conventional CT images. In qualitative image analysis, the 40-keV images were significantly higher than conventional CT images. Both qualitative and quantitative analyses showed that the image quality of VMIs at 40 keV was significantly higher than that of conventional CT images.

A Novel Method of CT Exophthalmometry in Patients With Thyroid Eye Disease.

Purpose:Conventional computed tomography (CT) exophthalmometry requires an intact lateral orbital wall and is therefore not feasible in patients who have undergone any form of lateral orbital wall surgery where the normal bony landmark may be lost or displaced. The purpose of our study is to validate an alternative method of CT exophthalmometry utilizing the posterior clinoid (PC) process as a new reference point that will allow for reproducible comparison of the anterior-posterior globe position in the preoperative and postoperative settings.Design:Cohort study.Methods:This is a retrospective study of 48 patients with clinically diagnosed thyroid eye disease who had undergone cross-sectional CT imaging in the pre- or postoperative settings. CT exophthalmometry was performed using both the conventional interzygomatic method and our proposed PC process method on all pre- and postoperative CT imaging by two independent observers. Interobserver variability analysis was performed with intraclass correlation coefficient. Correlation and agreement between the two methods were analyzed with Pearson correlation coefficient and linear regression method. All analyses were conducted at 5% level of significance with Stata MP V14.Results:Interobserver variability analysis showed an intraclass correlation coefficient of >0.9 for both interzygomatic and PC methods. There is good correlation between the two different measurements observed in both the pre- and postoperative groups (r = 0.68 and r = 0.72, respectively, P < 0.001). Linear regression showed good agreement between the two different measurements with most of the points lying within the 95% limits.Conclusions:Our new method agrees well with the conventional method and has the added benefit of being able to reliably assess the anterior-posterior globe position in patients who do not have intact lateral orbital walls after decompressive surgery.

Accuracy of registrations between cone-beam computed tomography and conventional computed tomography images and dose mapping methods in RaySearch software for the bladder during brachytherapy of cervical cancer patients.

PurposeThe aim of the study was to assess selected methods of image registration available in the RaySearch software and their impact on the accuracy of mapping of doses deposited in the bladder during brachytherapy (BRT) of cervical cancer in images used during external beam radiotherapy (EBRT).Material and methodsThe study was based on data from ten patients. Cone-beam computed tomography (CBCT) images (BRT) were aligned with CT images (EBRT) using four registration methods: Reg_1 (rigid), Reg_2a, Reg_2b (hybrid), and Reg_3 (biomechanical). Image mapping accuracy was evaluated based on bladder’s anatomy. Sørensen-Dice coefficient (DSC) values were analyzed for all the registrations. Discrepancies between triangular mesh points set on the basis of bladder contours were analyzed. Dose distributions from BRT were transformed according to registration results and mapped on CT images. Original BRT doses deposited in 2 cm3 volume of the bladder were compared to those transformed and associated with bladder’s volume determined on CT images.ResultsMean DSC values amounted to 0.36 (Reg_1), 0.87 and 0.88 (Reg_2a and Reg_2b), and 0.97 (Reg_3). Significant differences were found between DSC for the following comparisons: Reg_3/Reg_1 (p = 0.001), Reg_2a/Reg_1 (p = 0.011), and Reg_2b/Reg_1 (p = 0.014). The lowest discrepancies between triangular mesh points were for Reg_3 (p < 0.001, Reg_3 vs. Reg_1, and p = 0.039, Reg_3 vs. Reg_2b). Finally, the lowest discrepancies between the original and transformed doses were found for Reg_3. Nevertheless, only 5 out of 10 observations for Reg_3 yielded error of less than 5%.ConclusionsBiomechanical registration (Reg_3) enabled the most accurate alignment between CBCT and CT images. Satisfactory registration results of anatomical structures do not guarantee a correct mapping of primary BRT doses on the bladder delineated on CT images during EBRT. The results of dose transformation based on biomechanical registration had an error of less than 5% for only 50% of the observations.

Liver lesion localisation and classification with convolutional neural networks: a comparison between conventional and spectral computed tomography

Purpose: To evaluate the benefit of the additional available information present in spectral CT datasets, as compared to conventional CT datasets, when utilizing convolutional neural networks for fully automatic localisation and classification of liver lesions in CT images. Materials and Methods: Conventional and spectral CT images (iodine maps, virtual monochromatic images (VMI)) were obtained from a spectral dual-layer CT system. Patient diagnosis were known from the clinical reports and classified into healthy, cyst and hypodense metastasis. In order to compare the value of spectral versus conventional datasets when being passed as input to machine learning algorithms, we implemented a weakly-supervised convolutional neural network (CNN) that learns liver lesion localisation without pixel-level ground truth annotations. Regions-of-interest are selected automatically based on the localisation results and are used to train a second CNN for liver lesion classification (healthy, cyst, hypodense metastasis). The accuracy of lesion localisation was evaluated using the Euclidian distances between the ground truth centres of mass and the predicted centres of mass. Lesion classification was evaluated by precision, recall, accuracy and F1-Score. Results: Lesion localisation showed the best results for spectral information with distances of 8.22 ± 10.72 mm, 8.78 ± 15.21 mm and 8.29 ± 12.97 mm for iodine maps, 40 keV and 70 keV VMIs, respectively. With conventional data distances of 10.58 ± 17.65 mm were measured. For lesion classification, the 40 keV VMIs achieved the highest overall accuracy of 0.899 compared to 0.854 for conventional data. Conclusion: An enhanced localisation and classification is reported for spectral CT data, which demonstrates that combining machine-learning technology with spectral CT information may in the future improve the clinical workflow as well as the diagnostic accuracy.

Effectiveness of X-ray phase-contrast tomography: effects of pixel size and magnification on image noise

Noise magnitude in conventional attenuation X-ray tomography (CT) is strongly dependent on the pixel size and/or the geometrical magnification, thereby limiting the possibility of achieving high-resolution low-dose CT imaging. In this context, the use of Propagation-Based Imaging (PBI) phase-contrast technique coupled with the application of a suitable Phase-Retrieval (PhR) filter is a valuable tool to overcome such limitation. In fact, at fixed radiation dose, the noise dependence on the effective pixel size when the PhR filter is applied is much shallower with respect to conventional CT imaging. Making use of a theoretical framework developed by other authors, this work demonstrates quantitatively the dependence of CT image noise on pixel size and magnification in PBI. Calculations are compared with experimental images of a breast specimen imaged at the SYRMEP beamline at the Elettra synchrotron facility (Trieste, Italy), with a CdTe photon-counting detector in PBI configuration. The results, expressed in terms of Signal-to-Noise Ratio (SNR) gain due to the PhR application, show a good agreement between predictions and experimental data at all pixel pitches and magnifications, quantitatively demonstrating the importance of going towards detectors featuring smaller pixels (or higher spatial resolution) to fully exploit the advantages of PBI and PhR. Specifically, SNR gain up to a factor of 20 is observed at the smallest pixel pitch (60 μ m) and largest magnification (1.40). At the same time, as predicted theoretically, larger magnifications correspond to lower image noise (or higher SNR) when PhR is applied: this trend is unparalleled in attenuation-based CT imaging where larger magnifications, hence smaller effective pixel sizes, lead to a higher noise.

Comparison of 68Ga-Dotatate PET/CT and 18F-FDOPA PET/CT for the diagnosis of pancreatic neuroendocrine tumors in a MEN1 patient

ContextPancreatic neuroendocrine tumors (PNETs) occur in more than 80% of patients with multiple endocrine neoplasia type 1 (MEN1) syndrome, with predominance of small (<1cm) non-functioning tumors, followed by gastrinomas and insulinomas. Due to their small size, the diagnostic performance of conventional MRI and CT imaging is highly variable, with a real risk of false-negatives. Functional imaging on 111In-DTPA-Octreotide SPECT somatostatin receptor scintigraphy (Octreoscan®) is the modality of choice, but shows only 80% sensitivity. Alternatively, 18F-fluorodihydroxyphenylalanine (FDOPA) and, more recently, 68Ga-Dotatate PET/CT imaging are valuable options in case of negative Octreoscan®. Case reportA 55 old-year woman diagnosed with MEN1 syndrome, presented with multiple asymptomatic but progressive PNETs revealed on ultrasound endoscopy. Octreoscan® was negative, as was 18F-FDOPA PET/CT, whereas 68Ga-Dotatate PET/CT detected all PNETs found on endoscopy. ConclusionWe here report the first case of a MEN1 patient who successfully underwent a 68Ga-Dotatate PET/CT for detection and follow-up of PNETs, while both Octreoscan® and 18F-FDOPA PET/CT were negative.

Clinical Management of Risk of Radiation Pneumonia with Serum Markers During the Radiotherapy for Patients with Thoracic Malignant Tumors.

PurposeRisk of radiation pneumonia (RP) could not be effectively detected due to non-specific clinical symptoms in the early stage. The purpose of this investigation was to evaluate serum biomarkers of cytokines interleukin-6 (IL-6), C-reactive protein (CRP) and procalcitonin (PCT) for its early detection in patients with thoracic malignant tumors receiving radiotherapy.Patients and methodsThe clinical data of 105 patients with thoracic malignant tumors (lung cancer, esophageal carcinoma and mediastinal tumors) treated by radiotherapy were retrospectively analyzed. The patients were divided into RP group and non-RP group according to the Common Terminology Criteria for Adverse Events (CTCAE 5.0). The serum level of IL-6 was detected by chemiluminescence, and the level of CRP was measured by nephelometry during radiotherapy. The level of PCT, one of the specific indicators to distinguish infection and non-infectious etiologies, was also detected by chemiluminescence.ResultsAmong 105 patients treated by radiotherapy, 28 developed RP, and the other 77 had no RP. There was no significant difference in the risk of RP between patients’ factors (age, sex, PS score, smoking, tumor type) and treatment factors (chemotherapy, V5, GTV dose). However, chronic obstructive pulmonary disease (COPD), V20 and mean lung dose (MLD) were significantly different between the two groups (χ2 = 4.131, 3.986, 7.830, P < 0.05). Furthermore, PCT levels were also found to have insignificant differences between RP group and non-RP group (P > 0.05). However, there were significant differences between the groups in the levels of IL-6 and CRP (P < 0.05). The IL-6 levels significantly increased earlier than that of conventional CT imaging when patients suffering from RP and peaked at 6 weeks during radiotherapy. CRP had a similar change as IL-6. Single cytokine and combination of IL-6 and CRP possessed a good ability to predict RP with the AUC of IL-6 of 0.89±0.04 (95% CI, 0.80–0.95, P<0.001), CRP of 0.87±0.05 (95% CI, 0.78–0.94, P<0.001), IL-6 + CRP of 0.92 ± 0.03 (95% CI, 0.83–0.97, P < 0.001), respectively.ConclusionThe combined detection of serum IL-6, CRP and PCT may be an effectual method for early detection and clinical practice management of risk of RP.

Eliminating projection error of measuring Pauwels’ angle in the femur neck fractures by CT plane manipulation

ObjectivesThe aim for the present study was to determine whether projection error of measuring Pauwels’ angle in young femur neck fracture could be eliminated by CT plane manipulation. MethodsClinical data of displaced femur neck fractures in young adults aged 20 to 64years old (13 females and 17 males) were retrospectively analyzed. Their average age was 47.9years (range: 22–64years; SD: 11.3). Using modified measurement method for Pauwels’ angle using central line of the shaft as a guideline, the angle of a conventional coronal CT image was measured. CT images were imported into Mimics® software. The scanning plane was then reformatted parallel to the neck axis to eliminate projection error of injured limb. Measured angles were classified into three types (I<30°; II, 30–50°; and III>50°) and differences were analyzed. ResultsAverage Pauwels’ angle was 52.9° (range: 28.6–68.3°; SD: 9.9; type II, 17 cases; type III, 13 cases) for conventional CT images and 68.7° (range: 29.8–91.2°; SD: 13.4; type II, 1 cases; type III, 29 cases) for reformatted CT images. Difference between these two measurements on average was 15.7° (range: 1.2–34.9°; SD: 7.3). ConclusionsReformatting CT scanning plane by manipulating the proximal fragment to be parallel with the neck axis of the distal neck-shaft fragment is a convenient and reliable technique for eliminating the projection error of measuring Pauwels’ angle in the femur neck fractures. Level of evidenceIV, cohort study.

Multi‐“Color” Delineation of Bone Microdamages Using Ligand‐Directed Sub‐5 nm Hafnia Nanodots and Photon Counting CT Imaging

AbstractThe early detection of bone microdamages is crucial to make informed decisions about the therapy and taking precautionary treatments to avoid catastrophic fractures. Conventional computed tomography (CT) imaging faces obstacles in detecting bone microdamages due to the strong self‐attenuation of photons from bone and poor spatial resolution. Recent advances in CT technology as well as novel imaging probes can address this problem effectively. Herein, the bone microdamage imaging is demonstrated using ligand‐directed nanoparticles in conjunction with photon counting spectral CT. For the first time, Gram‐scale synthesis of hafnia (HfO2) nanoparticles is reported with surface modification by a chelator moiety. The feasibility of delineating these nanoparticles from bone and soft tissue of muscle is demonstrated with photon counting spectral CT equipped with advanced detector technology. The ex vivo and in vivo studies point to the accumulation of hafnia nanoparticles at microdamage site featuring distinct spectral signal. Due to their small sub‐5 nm size, hafnia nanoparticles are excreted through reticuloendothelial system organs without noticeable aggregation while not triggering any adverse side effects based on histological and liver enzyme function assessments. These preclinical studies highlight the potential of HfO2‐based nanoparticle contrast agents for skeletal system diseases due to their well‐placed K‐edge binding energy.

Value of CT-Based Texture Analysis in Preoperative Prediction of the Grade of Gastrointestinal Stromal Tumors Compared to Conventional CT Imaging

Background: Gastrointestinal stromal tumors (GISTs), which are the most common mesenchymal tumors of the digestive system, are classified as very low, low, intermediate and high risk. The treatment and prognosis of GISTs vary according to the grade. Objectives: To investigate the capability of computed tomography (CT) -based texture analysis for predicting the grade of GISTs, and compare the findings with a combination model consisting of CT signs and texture parameters. Patients and Methods: For this retrospective study, a total of 168 patients (training group: n = 117; validation group: n = 51) with pathologically proven GISTs were analyzed. Patients were randomly divided into the potential malignant and malignant group. Radiomics signature based on texture features and the combination model consisting of selected CT signs and texture parameters were developed with the least absolute shrinkage and selection operator (Lasso) regression. The prediction performance of models was evaluated by the area under the receiver operating characteristic (ROC) curve (AUC). Calibration was evaluated with the Hosmer-Lemeshow goodness-of-fit test. Results: Totally, 29 texture features and seven CT signs were extracted. Texture features of sphericity, compacity, contrast, and dissimilarity, and CT signs of size, and location were selected to develop the predictive models. The rad- and pre-scores were calculated for the radiomics signature and combination model based on the validation group. Both two models hold great prediction performance with AUCs of 0.897 and 0.959 (P 0.05). Conclusion: The prediction models were validated to be valuable for risk grade of GISTs and may provide non-invasive and practical biomarkers for optimizing the treatment strategy and improving the prognosis. In addition, the combination model had more advantages than texture analysis alone.

Initial Clinical Experience of Virtual Monoenergetic Imaging Improves Stent Visualization in Lower Extremity Run-Off CT Angiography by Dual-Layer Spectral Detector CT

Virtual monoenergetic imaging (VMI) may improve stent visualization in lower extremity run-off computed tomography angiography. The purpose of this study was to evaluate the image quality (IQ) of stents and to determine the optimal kiloelectron volt (keV) level of VMI images for stent evaluation compared to conventional CT images. This study included 32 patients with prior stent placement who underwent run-off computed tomography angiography on a dual-layer spectral detector CT scanner. Thirteen image series were evaluated for each stent, including conventional CT and 12 VMI datasets from 40 keV to 150 keV obtained in 10-keV intervals. Attenuation, SD, contrast-to-noise ratio, and signal-to-noise ratio of the native vessel and the vessel with a stent were evaluated. The diameter of the stent was measured in all 13 image series. The IQ was evaluated by two readers using a five-point scale (1 = poor IQ, 5 = excellent IQ). A total of 39 stents in 29 patients were evaluated. Compared to conventional CT, attenuation of the native vessel and the vessel with a stent was higher at 40-60 keV, and the SD was equal or lower at 50-150 keV. Based on the attenuation and SD of VMI images, the contrast-to-noise ratio and signal-to-noise ratio were higher at 40-70 keV, among which the highest ratios were obtained at 40 keV. The stent diameter was equal or larger at 60-150 keV, and the lowest stent diameter underestimation occurred at 100 keV. The IQ was equal or higher, ranging from 60 to 100 keV in comparison with conventional CT, and the highest IQ score occurred at 90 keV. This quantitative and qualitative assessment of VMI images and conventional images indicated that IQ improvement and more accurate stent lumen evaluation on lower extremity run-off CT angiography can be achieved by dual-layer spectral detector CT.