Conventional Computed Tomography Imaging Research Articles

Computed Tomography Image Features under Denoising Algorithm for Benign and Malignant Diagnosis of Renal Parenchymal Tumor.

To improve the quality of computed tomography (CT) images and provide help for benign and malignant diagnosis of renal parenchymal tumors, the independent component analysis (ICA) denoising algorithm was used. An improved ICA X-ray CT (X-CT) medical image denoising algorithm was proposed. ICA provided a higher signal-to-noise ratio for CT image denoising. Forty patients with renal tumor were selected as the observation group. The CT image performance of patients was evaluated by the denoising algorithm and compared with the wavelet transform algorithm, and the peak signal-to-noise ratio of the proposed algorithm was analyzed and compared. The results showed that among the 40 patients with renal tumors, 12 were renal clear cell carcinoma cases and 28 were cystic renal carcinoma cases. The accuracy of the enhanced CT image was 93.8%, and that of the CT image using the denoising algorithm was 96.3%; the difference between the two was significant (P < 0.05). The peak signal-to-noise ratio (PSNR) of the algorithm proposed was higher than the PSNR values of CT and noisy images. The PSNR of the proposed algorithm was significantly higher than that of mean filtering. The root mean square error (RMSE) algorithm of the proposed algorithm was significantly lower than that of the mean algorithm in image data processing (P < 0.05), which showed the superiority of the proposed algorithm. Enhanced CT can be staged significantly. In conclusion, the algorithm had a significant effect on the edge contour of detailed features, and the accuracy of CT images based on intelligent calculation was significantly higher than that of conventional CT images for benign and malignant renal parenchyma tumors, which was worth promoting in clinical diagnosis.

Feasibility of artificial intelligence\u2013supported assessment of bone marrow infiltration using dual-energy computed tomography in patients with evidence of monoclonal protein \u2014 a retrospective observational study

ObjectivesTo demonstrate the feasibility of an automated, non-invasive approach to estimate bone marrow (BM) infiltration of multiple myeloma (MM) by dual-energy computed tomography (DECT) after virtual non-calcium (VNCa) post-processing.MethodsIndividuals with MM and monoclonal gammopathy of unknown significance (MGUS) with concurrent DECT and BM biopsy between May 2018 and July 2020 were included in this retrospective observational study. Two pathologists and three radiologists reported BM infiltration and presence of osteolytic bone lesions, respectively. Bone mineral density (BMD) was quantified CT-based by a CE-certified software. Automated spine segmentation was implemented by a pre-trained convolutional neural network. The non-fatty portion of BM was defined as voxels > 0 HU in VNCa. For statistical assessment, multivariate regression and receiver operating characteristic (ROC) were conducted.ResultsThirty-five patients (mean age 65 ± 12 years; 18 female) were evaluated. The non-fatty portion of BM significantly predicted BM infiltration after adjusting for the covariable BMD (p = 0.007, r = 0.46). A non-fatty portion of BM > 0.93% could anticipate osteolytic lesions and the clinical diagnosis of MM with an area under the ROC curve of 0.70 [0.49–0.90] and 0.71 [0.54–0.89], respectively. Our approach identified MM-patients without osteolytic lesions on conventional CT with a sensitivity and specificity of 0.63 and 0.71, respectively.ConclusionsAutomated, AI-supported attenuation assessment of the spine in DECT VNCa is feasible to predict BM infiltration in MM. Further, the proposed method might allow for pre-selecting patients with higher pre-test probability of osteolytic bone lesions and support the clinical diagnosis of MM without pathognomonic lesions on conventional CT.Key Points• The retrospective study provides an automated approach for quantification of the non-fatty portion of bone marrow, based on AI-supported spine segmentation and virtual non-calcium dual-energy CT data.• An increasing non-fatty portion of bone marrow is associated with a higher infiltration determined by invasive biopsy after adjusting for bone mineral density as a control variable (p = 0.007, r = 0.46).• The non-fatty portion of bone marrow might support the clinical diagnosis of multiple myeloma when conventional CT images are negative (sensitivity 0.63, specificity 0.71).

Computed tomography-based calcium scoring in cadaver leg arteries: Influence of dose, reader, and reconstruction algorithm

PurposeComputed tomography (CT) might be a good diagnostic test to accurately quantify calcium in vascular beds but there are multiple factors influencing the quantification. The aim of this study was to investigate the influence of different computed tomography protocol settings in the quantification of calcium in the lower extremities using modified Agatston and volume scores. MethodsFresh-frozen human legs were scanned at different tube current protocols and reconstructed at different slice thickness. Two different iterative reconstruction protocols for conventional CT images were compared. Calcium was manually scored using modified Agatston and volume scores. Outcomes were statistically analyzed using Wilcoxon signed-rank tests and mean absolute and relative differences were plotted in Bland-Altman plots. ResultsOf the 20 legs, 16 had CT detectable calcifications. Differences between thick and thin slice reconstruction protocols were 129 Agatston units and 125% for Agatston and 78.4 mm3 and 57.8% for volume (all p ≤ 0.001). No significant differences were found between low and high tube current protocols. Differences between iDose4 and IMR reconstruction protocols for modified Agatston were 34.2 Agatston units and 17.7% and the volume score 33.5 mm3 and 21.2% (all p ≤ 0.001). ConclusionsSlice thickness reconstruction and reconstruction method protocols influenced the modified Agatston and volume scores in leg arteries, but tube current and different observers did not have an effect. This data emphasizes the need for standardized quantification of leg artery calcifications. Possible implications are in the development of a more universal quantification method, independent of the type of scan and vasculature.

Advanced Noise-Optimized Dual-Energy Virtual Monochromatic Imaging vs. Conventional 120-kVp CT Imaging: Image Quality Assessment

Purpose: This study aimed at evaluating the image quality characteristics of advanced noise-optimized and traditional virtual monochromatic images compared with conventional 120-kVp images from second-generation Dual-Source CT. Materials and Methods: For spiral scans six syringes filled with diluted iodine contrast material (1, 2, 5, 10, 15, 20 mg I/ml) were inserted into the test phantom and scanned with a second-generation dual-source CT in both single-energy (120-kVp) and dual-energy modes. Images set contain conventional single-energy 120-kVp, and virtual monochromatic were reconstructed with energies ranging from 40 to 190-keV in 1-keV steps. An energy-domain noise reduction algorithm was applied and the mean CT number, image noise, and iodine CNR were calculated. Results: The iodine CT number of conventional 120-kVp images compared with monochromatic of 40-, 50-, 60- and 70-keV images showed increase. The improvement ratio of image noise on Advanced Virtual Monochromatic Images (AVMIs) compared with the Traditional Virtual Monochromatic Images (TVMIs) at energies of 40-, 50-, 60, 70-keV was 52.9%, 35.7%, 8.1%, 2.1%, respectively. At AVMIs from 75- to 190-keV, the image noise value was less than conventional 120-kVp images. CNR improvement ratio at 20 mg/ml of iodinated contrast material for TVMIs and AVMIs compared to 120-kVp CT images and AVMIs compared to TVMI was 18.3% and 56.3%, 32.1% respectively. Conclusion: Both TVMIs (in energies ranging from 54 to 71-keV) and AVMIs (in energies ranging from 40 to 74-keV) represent improvement in the iodine contrast-to-noise ratio than conventional 120-kVp CT images for the same radiation dose. Also, AVMIs compared to TVMIs have been obtained considerable noise reduction and CNR improvement for low-energy virtual monochromatic images. In the present study, we show that virtual monochromatic image and its Advanced version (AVMI) may boost the dual-energy CT advantages by providing higher CNR images in the same exposure value compared to routinely acquired single-energy CT images.

Optimized Backprojection Filtration Algorithm for Postoperative Reduction and Analysis of Respiratory Infection-Related Factors of Pelvic Fractures by CT Imaging

To explore the computed tomography (CT) imaging characteristics and BPF algorithm fine lung CT image efficiency for the diagnosis of pelvic fracture patients and assist clinicians to carry out the disease care and treatment, CT images based on optimized back-projection filtering (BPF) algorithm were utilized to diagnose postoperative reduction of pelvic fractures and penetrating lung infection caused by long-term bed rest. A total of 100 patients with pelvic fracture were selected and all of them underwent pelvic fracture surgery and were rolled into conventional CT diagnosis group (conventional group) and BPF algorithm optimized CT image diagnosis group (BPF group). One group used conventional CT images to guide pelvic reduction and detect lung infections, and the other used BPF algorithm to optimize the images. The results showed that the BPF group was superior to the conventional CT group in both image clarity and shadow area, and the peak signal-to-noise ratio (PSNR) was significantly better than that of the conventional group ( P &lt; 0.05 ). Nine more cases were detected in the algorithm group than in the conventional group, and the incidence of complications was 48% in the conventional group and 28% in the BPF group, with a statistical difference of 20% between the two groups ( P &lt; 0.05 ). In addition, the satisfaction of returning patients was 96% in the BPF group and 77% in the conventional group ( P &lt; 0.05 ). The diagnosis of pulmonary infection was more obvious in the BPF group, indicating that BPF optimization of the CT image was suitable for clinical diagnosis and had a practical application value.

Classification Algorithm-Based CT Imaging in Diagnosis of Acute Respiratory Distress Syndrome and Analysis of Pathogenic Factors

The study focused on the application value of classification algorithms in processing CT images of acute respiratory distress syndrome (ARDS) and aimed to analyze the pathogenic factors of ARDS. A total of 60 ARDS patients in hospital were selected, and they were divided into ARDS group (38 cases) and non-ARDS group (22 cases) as per diagnostic criteria. There was no significant difference in general data between the two groups ( P &gt; 0.05 ). The FWAC algorithm was introduced into CT imaging to classify the image data more accurately. The two groups were compared for the left ventricular ejection fraction (LVEF), oxygenation index PaO2/FiO2 (P/F), Acute Physiology and Chronic Health Evaluation (APACHE II) scores, pH, and PaO2. The results showed that the PaO2, P/F, and APACHE II scores of the two groups were not statistically significant ( P &gt; 0.05 ). The P/F of the ARDS group was 136.12, and that of the non-ARDS group was 143.04; the APACHE II score of the ARDS group was 40.1, and that of the non-ARDS group was 62.3, showing no significant difference ( P &gt; 0.05 ); the LVEF of the ARDS group was 58.14, and that of the non-ARDS group was 46.26, showing statistically significant differences ( P &gt; 0.05 ). When the minimum support was 0.3 and the minimum confidence was 0.5, the value of Recurrence was 0.7082 and the value of Diagnosis was 0.968. The rules generated by the FWAC algorithm can accurately predict the category and were consistent with the expected results. The accuracy of this algorithm was as high as 98.7%, which was significantly higher than that of the conventional CT imaging (88.4%). The rules generated by FWAC were more accurate, assisting doctors in the prevention and diagnosis of ARDS disease. Premature delivery and asphyxia are high-risk factors of ARDS. In conclusion, the FWAC algorithm has a good classification ability of the CT images of ARDS and demonstrates high accuracy.

Association of Pericoronary Adipose Tissue Quality Determined by Dual-Layer Spectral Detector CT With Severity of Coronary Artery Disease: A Preliminary Study.

Background: Pericoronary adipose tissue (PCAT) is considered as a source of inflammatory mediators, leading to the development of coronary atherosclerosis. The study aimed to investigate the correlation between PCAT quality derived from dual-layer spectral detector CT (SDCT) and the severity of coronary artery disease (CAD), and whether PCAT parameters were independently associated with the presence of CAD.Materials and Methods: A total of 403 patients with symptoms of chest pain who underwent SDCT were included. PCAT quality including fat attenuation index (FAI) measured from conventional polychromatic CT images (FAI120kvp) and spectral virtual mono-energetic images at 40 keV (FAI40keV), slope of spectral HU curve (λHU), and effective atomic number (Eff-Z) were measured around the lesions representing the maximal degree of vascular stenosis in each patient. Meanwhile, overall epicardial adipose tissue (EAT) attenuation was acquired in the conventional polychromatic energy imaging.Results: FAI40keV, λHU, Eff-Z, and FAI120kvp increased along with the degree of CAD in general and were superior to the overall EAT attenuation for detecting the presence of CAD. Multivariate logistic regression analysis indicated that FAI40keV was the most powerful independent indicator (odds ratio 1.058, 95% CI 1.044–1.073; p < 0.001) of CAD among these parameters. Using an optimal cut-off (−131.8 HU), FAI40keV showed higher diagnostic accuracy of 80.6% compared with the other parameters.Conclusions: These preliminary findings suggest that FAI40keV on SDCT may be an appealing surrogate maker to allow monitoring of PCAT changes in the development of CAD.

Feasibility of magnetic resonance-only high-dose-rate surface brachytherapy for clinical application.

In this article, we investigate the feasibility of magnetic resonance (MR)-only imaging for high-dose-rate (HDR) surface brachytherapy (SABT). We examined whether a standard CT-based planning can be replaced with an MR-only planning. For this purpose, the MRI digitization and plan quality check processes were compared against the standard CT-based processes. A prospective clinical implementation of the MR-only planning was evaluated on a clinical data set. A pointwise encoding time reduction with radial acquisition (PETRA) sequence was optimized for visualization of Freiburg flap (FF) on MR images. MR and conventional CT images were acquired with a FF applicator (Elekta, Stockholm, Sweden) placed on the following phantoms: (1) flat styrofoam (FST), FF locked-in placed with supporting structure; (2) cast-made facemask, and (3) porcine leg (PL). Catheters were digitized and activated with 10mm step size on Oncentra Brachy 4.5.3 Treatment Planning System. The CT-only and MR-only treatment plans were generated by optimizing the dose to the target defined as volume at 3mm skin depth. To compare the plans, the MRI-to-CT alignment was performed via rigid registration. Positional displacements of dwell positions between CT and MR plans were compared on the FST phantom and the relative percent dose difference in 2210 different points from CT or MR-only plans was compared. For all three phantoms, the comparabilities between CT and MR-only plans were assessed by calculating dice similarity coefficient (DSC) for volumes enclosing 150%, 125%, 100%, 95%, 90%, 80%, and 65% isodose lines (V150 -V65 ). The MR images of FF placed on the forearm of a healthy subject were acquired with this optimized PETRA sequence and used for treatment planning. The relative percent dose was calculated on 140 representative points placed at 3mm skin depth to evaluate the dose to the skin. Using the optimized PETRA sequence, MRTP digitization accuracy was<1mm in each dimension and on three-dimensional (3D) displacement for the FST phantom. In each phantom and clinical data set, it was possible to generate MR-only treatment plans with the 3mm skin depth prescription. In the FST phantom, the mean relative dose at the points was not significantly different(<0.1% difference) for CT or MR-based plans. The assessment of similarities in dose profiles between CT and MR-only plans' provided DSC values greater than 0.96, 0.92, and 0.73 for all volumes enclosing up to 100%, 125%, and 150% isodose lines, respectively. The feasibility of generating a HDR treatment plan with FF using MR-only has been evaluated in phantoms with varying geometry and for a clinical data set. The optimization of a standard MRI sequence-PETRA-implemented in this study showed that FF-based catheters can be digitized and a plan can be generated using only MRI. The resulting MR-only plans were comparable to the conventional CT-based plans, suggesting that MRI alone can generate clinically acceptable plans for FF in phantoms and on a clinical data set. Reliable MR-only treatment planning could improve treatment prescription through more accurate characterization of soft tissue targets.

A Quantitative Analysis of Subchondral Bone Density Around Osteochondritis Dissecans Lesions of the Capitellum

In capitellar osteochondritis dissecans (OCD), unstable lesions generally demonstrate signs of subchondral sclerosis. We postulate that OCD lesions have abnormal subchondral bone density. We aimed to quantify the subchondral bone thickness around OCD lesions using conventional computed tomography (CT) imaging. This retrospective study included 15 patients with capitellar OCD (OCD group) and 12 patients with an unaffected radio-capitellar joint (control group). We constructed 3-dimensional humerus models using CT data and quantified the bone density with colored contour mapping to determine the subchondral bone thickness. We measured the thickness relative to the condylar height at the centroid and lateral, medial, superior, and inferior edge points of the OCD lesion, and compared the findings between the groups. We then correlated the CT measurements with the magnetic resonance imaging measurements. Subchondral bone thickness at the centroid and lateral, medial, superior, and inferior edges in the OCD group was significantly higher than that in the control group. Correlation analyses revealed that the magnetic resonance imaging measurements highly correlated with the CT subchondral bone measurements. We found that there is a zone of increased subchondral bone thickness around OCD lesions that should be considered during drilling, microfracture, or other reconstruction methods. We observed a high correlation with low errors between the measurements taken from conventional CT images and the measurements from magnetic resonance imaging, suggesting that both modalities are useful in clinical decision making. Diagnostic IV.

Unenhanced Dual-Layer Spectral-Detector CT for Characterizing Indeterminate Adrenal Lesions.

Background Unenhanced dual-layer spectral-detector CT may facilitate adrenal lesion characterization; however, no studies have evaluated its incremental diagnostic yield for indeterminate lesions (unenhanced attenuation >10 HU) in comparison to that with conventional unenhanced CT. Purpose To determine whether spectral attenuation analysis improves characterization of lipid-poor adrenal adenomas from nonadenomas compared to that with mean attenuation and histogram analysis of conventional CT images. Materials and Methods This retrospective study included patients with indeterminate adrenal lesions who underwent unenhanced dual-layer spectral-detector CT between March 2018 and June 2020. Mean attenuation on conventional 120-kVp images (HUconv), histogram-based percentage negative pixels (proportion of all pixels <0 HU) on conventional 120-kVp images, and mean attenuation on virtual monoenergetic images (VMIs) at 40-140 keV were measured for each lesion. The attenuation difference between virtual monoenergetic 140- and 40-keV images (ΔHU; ie, Hounsfield unit at 140 keV - Hounsfield unit at 40 keV) and ΔHU indexed with HUconv (ΔHU index; ie, ΔHU/HUconv × 100) were calculated. Conventional and virtual monoenergetic imaging parameters were compared between lipid-poor adenomas and nonadenomas by using the Mann-Whitney U test. Receiver operating characteristic analysis was performed to determine the sensitivity for attaining at least 95% specificity in characterizing adenomas from nonadenomas; sensitivity was compared by using the McNemar test. Results A total of 232 patients (mean age ± standard deviation, 67 years ± 11; 145 men) with 129 lipid-poor adenomas and 103 nonadenomas were evaluated. HUconv and mean attenuation on VMIs at 40-140 keV were lower and the percentage negative pixels, ΔHU, and ΔHU index higher in lipid-poor adenomas than in nonadenomas (P < .001 for all). Attenuation differences between adenomas and nonadenomas on VMIs were maximal at 40 keV (23 HU at 40 keV vs 5 HU at 140 keV). The highest sensitivities for differentiating adenomas and nonadenomas were achieved for virtual monoenergetic ΔHU index (77% [99 of 129 adenomas]), attenuation on 40-keV images (71% [91 of 129 adenomas]), and ΔHU (67% [87 of 129 adenomas]) compared to HUconv (35% [45 of 129 adenomas]) and percentage negative pixels (30% [39 of 129 adenomas]) (P < .001 for all; specificity, 95% [98 of 103 nonadenomas]). Conclusion Spectral attenuation analysis enabled differentiation of lipid-poor adenomas from nonadenomas with higher sensitivity than mean attenuation or histogram analysis of conventional CT images. © RSNA, 2021 Online supplemental material is available for this article.

Dynamic, Time-resolved CT Angiography Characterizes Aortic Endoleak Type, Inflow With out Additional Radiation Exposure and Provides Image Guidance for Targeted Treatment Approach

Conventional computed tomography (CT) and ultrasound imaging remain the standard for endovascular aneurysm repair (EVAR) surveillance. Variability in contrast arrival and washout time in CT imaging precludes accurate characterization of endoleak type and identifying target vessels for treatment. The objectives of this study were to: (1) validate dynamic, time-resolved CT angiographic imaging (d-CTA) findings with 2D angiography (DSA); (2) compare the radiation burden with conventional triphasic (t-CTA); and (3) demonstrate the feasibility of d-CTA in targeting endoleak intervention.

Comparison between conventional CT and grayscale inversion CT images in the assessment of the post-operative spinal orthopaedic implants

AimTo compare the accuracy of the inverted greyscale CT versus the conventional CT in the assessment of post-operative spinal orthopaedic implants and osseous fusion. Methods50 patients who had CT as part of their routine spinal implant follow up were evaluated for the presence of fusion, fracture and loosening with conventional CT and with greyscale inverted CT images. 3 independent observers assessed the images 2 months apart. Diagnostic performance (sensitivity and specificity) of the conventional and greyscale inversion images relative to the reference standard were calculated. Agreement with the reference standard was assessed using Cohen's kappa for conventional and greyscale inversion images. ResultsCorrect classifications increased when using the greyscale inverted CT images for each reader compared to conventional CT images (40–46, 39 to 42 and 41 to 44 (out of 50)). Inverted images demonstrated better agreement with the reference standard than conventional grayscale images for assessment of fusion (kappa of 0.588 for inverted CT versus 0.484 for conventional CT) and loosening (kappa 0.386 for inverted versus 0.293 for conventional). Sensitivity was increased for assessment of fusion and loosening. McNemar's test performed for assessment of sensitivity differences showed statistical significance (p = 0.038 for fusion and p = 0.0313 for loosening). ConclusionGreyscale inversion CT is a useful adjunct which has advantages (improved sensitivity and better agreement) over conventional CT imaging in cases of fusion and loosening of metallic implants following spinal instrumentation. We recommend the use of both the greyscale inversion CT images and conventional CT imaging when assessing post-operative spinal orthopaedic implants.

PET-Based Staging Is Cost-Effective in Early-Stage Follicular Lymphoma.

The objective was to assess the cost-effectiveness of staging PET/CT in early-stage follicular lymphoma (FL) from the Canadian health-care system perspective. Methods: The study population was FL patients staged as early-stage using conventional CT imaging and planned for curative-intent radiation therapy (RT). A decision analytic model simulated the management after adding staging PET/CT versus using staging CT alone. In the no-PET/CT strategy, all patients proceeded to curative-intent RT as planned. In the PET/CT strategy, PET/CT information could result in an increased RT volume, switching to a noncurative approach, or no change in RT treatment as planned. The subsequent disease course was described using a state-transition cohort model over a 30-y time horizon. Diagnostic characteristics, probabilities, utilities, and costs were derived from the literature. Baseline analysis was performed using quality-adjusted life years (QALYs), costs (2019 Canadian dollars), and the incremental cost-effectiveness ratio. Deterministic sensitivity analyses were conducted, evaluating net monetary benefit at a willingness-to-pay threshold of $100,000/QALY. Probabilistic sensitivity analysis using 10,000 simulations was performed. Costs and QALYs were discounted at a rate of 1.5%. Results: In the reference case scenario, staging PET/CT was the dominant strategy, resulting in an average lifetime cost saving of $3,165 and a gain of 0.32 QALYs. In deterministic sensitivity analyses, the PET/CT strategy remained the preferred strategy for all scenarios supported by available data. In probabilistic sensitivity analysis, the PET/CT strategy was strongly dominant in 77% of simulations (i.e., reduced cost and increased QALYs) and was cost-effective in 89% of simulations (i.e., either saved costs or had an incremental cost-effectiveness ratio below $100,000/QALY). Conclusion: Our analysis showed that the use of PET/CT to stage early-stage FL patients reduces cost and improves QALYs. Patients with early-stage FL should undergo PET/CT before curative-intent RT.

Diagnostic Accuracy of Dual-Layer Spectral CT Using Electron Density Images to Detect Post-Traumatic Prevertebral Hematoma of the Cervical Spine.

To investigate the diagnostic value of dual-layer spectral detector computed tomography (SDCT) in detecting posttraumatic prevertebral hematoma of the cervical spine by including electron density images. 38 patients with post-traumatic imaging of the cervical spine were included in this study and received both SDCT and MRI examinations. MRI was set as the reference and combined conventional/electron density (C + ED) images were compared to conventional CT (CCT) images alone. A total of 18 prevertebral hematomas were identified. Reader 1 identified 14 of 18 and reader 2 15 of 18 prevertebral hematomas by using C + ED reconstructions. Readers 1 and 2 detected 6 and 9 of 18 hematomas on CCT, respectively. CCT showed a sensitivity of 33-50 % and a specificity of 75-80 %, while for C + ED reconstructed images the sensitivity was 77-83 % and the specificity was 85-90 %. Accuracy increased from 55-66 % to 84 % by using C + ED images. The minimum thickness for detecting hematoma on C + ED images was 3 mm. The sizes of prevertebral hematoma on CCT/C + ED were not significantly under- or overestimated compared to the MRI reference. There was a significant difference between the two readers for measuring hematoma sizes on CCT (p = 0.04). Readers showed an excellent inter-rater reliability (kappa = 0.82) for C + ED images and a moderative inter-rater reliability (kappa = 0.44) for CCT. With SDCT, the diagnostic accuracy for detecting post-traumatic prevertebral hematoma is improved by using combined conventional and electron density reconstructions compared to conventional images alone. · SDCT has a high potential for detecting post-traumatic prevertebral hematomas of the cervical spine by using combined conventional and electron density images.. · Prevertebral hematomas with a thickness of less than 3 mm cannot be reliably identified by SDCT.. · There is no discernible value of conventional SDCT images for diagnosing prevertebral hematoma.. · Sedaghat S, Langguth P, Larsen N et al. Diagnostic Accuracy of Dual-Layer Spectral CT Using Electron Density Images to Detect Post-Traumatic Prevertebral Hematoma of the Cervical Spine. Fortschr Röntgenstr 2021; 193: 1445 - 1450.

Assessment of multi-energy inter-pixel coincidence counters for photon-counting detectors at the presence of charge sharing and pulse pileup: A simulation study.

Spectral distortion due to charge sharing (CS) and pulse pileup (PP) in photon-counting detectors (PCDs) degrades the quality of PCD data. We recently proposed multi-energy inter-pixel coincidence counters (MEICC) that provided spectral cross-talk information related to CS. When PP was absent, the normalized Cramér-Rao lower bounds (nCRLBs) of 225-µm pixel PCDs with MEICC was comparable to those of 450-µm pixel PCD without MEICC. The aim of this study was to assess the performance of PCDs with MEICC in the presence of both CS and PP using computer simulations. An in-house Monte Carlo program was modified to incorporate the following four temporal elements: (1) A pulse shape with a pulse duration of 20ns, (2) delays of up to 10ns in anode arrival times when photons were incident on pixel boundaries, (3) offsets proportional to a vertical separation between the primary and secondary charge clouds at the rate of ±4ns per ±100µm, and (4) a stochastic fluctuation of anode arrival times for all of the charge clouds with a standard deviation of 2ns. We assessed the performance of five PCDs, (a)-(f), for three spectral tasks, (A)-(C): (a) The conventional PCD, (b) a PCD with MEICC, (c) a PCD with one coincidence counter (1CC), (d) a PCD with a 3×3 analog charge summing scheme (ACS), and (e) a PCD with a 3×3 digital count summing scheme (DCS); (A) conventional CT imaging with water (i.e., linear attenuation coefficient maps), (B) water-bone material decomposition, and (C) K-edge imaging with tungsten. The tube current was changed from 1mA to 1000mA and the nCRLB was assessed. The recorded count rate curves were fitted by the non-paralyzable detection model with the effective deadtime parameter. The best fit was achieved by 25.8ns for the conventional PCD, 18.6ns for MEICC and 1CC, 140.5ns for ACS, and 209.0ns for DCS. The nCRLBs were strongly dependent on count rates. MEICC provided the best nCRLBs for all of the imaging tasks over the count rate range investigated except for a few conditions such as K-edge imaging at 1mA. PP decreased the merit of MEICC over the conventional PCD in addressing CS. Nonetheless, MEICC consistently provided better nCRLBs than the conventional PCD did. The nCRLBs of MEICC were in the range of 49-58% of those of the conventional PCD for K-edge imaging, 45-76% for water-bone material decomposition, and 81-88% for the conventional CT imaging (i.e., linear attenuation coefficient maps). ACS provided better nCRLBs than the conventional PCD did only when the effect of PP was minor (e.g., when the counting efficiency of the conventional PCD was higher than 0.95 with the tube current of up to 100mA). Besides a few cases, MEICC provides the best nCRLBs for all of the tasks at all of the count rates. ACS and DCS provide better nCRLBs than the conventional PCD does only when count rates are very low.

Application of different imaging methods for the localization of cerebrospinal fluid rhinorrhea: a comparative study.

CSF rhinorrhea is a type of CSF leakage caused by an aseptic abnormal passage between the subarachnoid space and the adjacent sinus and nasal cavity due to a cranial dural defect. At present, the value of computed tomography cisternography (CTC) in locating CSF rhinorrhea has been widely recognized, and magnetic resonance hydrography (MRH), as a heavy T2-weighted water imaging, plays a pivotal role in showing the location of the leak. In this paper, we retrospectively summarize the imaging manifestations seen at our hospital of patients with clinically confirmed CSF rhinorrhea at the skull base and evaluate the diagnostic value of different imaging methods in the localization of CSF rhinorrhea by means of preoperative imaging analysis using CTC and MRH. Fifty-five patients with CSF rhinorrhea admitted to our department from October 2016 to January 2021 were retrospectively analyzed. The patients' conventional CT, CTC, and MRH imaging data were compared, and the location of the leak determined preoperatively matched the location of the leak found during surgery. Moreover, there was no recurrence during the follow-up period of 4 months to 3 years. There were statistically significant differences between the diagnostic positivity rate of CTC and spiral CT (χ2=16.755, P<0.00), and between the diagnostic positivity rate of cranial MRH and spiral CT (χ2=6.338, 6.338=0.01), and no statistically significant difference between the diagnostic positivity rate of CTC and cranial MRH (χ2=2.625, P=0.1). The combined use of imaging techniques has important practical significance for the proper treatment and prognostic evaluation of CSF rhinorrhea. CTC has the highest positive rate for the diagnosis of CSF rhinorrhea, followed by MRH, while spiral CT is safer. CTC and MRH can promote the diagnostic rate in determining the location of CSF rhinorrhea, and selective combined application can be an important guide to surgery.

Ultra-High-Resolution Coronary CT Angiography for Assessment of Patients with Severe Coronary Artery Calcification: Initial Experience.

Conventional CT technology yields only modest accuracy of coronary artery stenosis assessment in severely calcified lesions. Reported herein are this study's initial observations on the potential of ultra-high-resolution CT (UHR-CT) for evaluating severely calcified coronary arterial lesions. Fifteen patients 45 years of age or older, with history of coronary artery disease, referred for invasive coronary angiography, were prospectively enrolled. Patients underwent UHR-CT within 30 days prior to cardiac catheterization. Image noise levels and diagnostic confidence (level 1-5) using UHR-CT were compared with reconstructed images simulating conventional CT technology. Stenosis assessment for the major coronary arteries and the left main coronary artery with UHR-CT and invasive angiography were compared. Results from clinically driven coronary CT using conventional technology were considered for comparison when available. Mean patient age was 67 years (range, 53-79 years). Thirteen patients were men, nine had obesity. Radiation dose was 9.3 mSv owing to expanded x-ray exposure to accommodate research software application (70%-99% of R-R cycle). Overall image noise was considerably greater for UHR-CT (50.9 ± 7.8 [standard deviation]) versus conventional CT image reconstruction (19.5 ± 8.3, P < .01), yet diagnostic confidence scores for UHR-CT were high (4.3 ± 0.9). Average calcium score in patients without stents (n = 6) was 1205, and of 86 vessels evaluated, 22 had 70% or greater stenosis depicted with invasive angiography (26%). Stenosis comparison with invasive angiography yielded 86% (19 of 22) sensitivity and 88% (56 of 64) specificity (95% CI: 65%, 97%; and 77%, 95%, respectively). Initial observations suggest UHR-CT may be effective in overcoming the limitation of conventional CT for accurately evaluating coronary artery stenoses in severely calcified vessels.Keywords: CT-Angiography, Coronary Arteries, ArteriosclerosisClinical trial registration no. NCT04272060See also commentary by Shanbhag and Chen in this issue.© RSNA, 2021.

Dual-Layer Spectral CT Imaging of Upper Aerodigestive Tract Cancer: Analysis of Spectral Imaging Parameters and Impact on Tumor Staging.

Dual-layer spectral CT is a novel technology that utilized conventional single-tube CT acquisition with a dual-layer detector for the separation of high and low-energy photons to create spectral data for material decomposition. We evaluated the spectral parameters of iodine density and Z-effective values in primary head and neck squamous cell carcinoma and determined its impact on local tumor staging. Twenty-one patients with primary head and neck squamous cell carcinoma and 15 healthy controls were retrospectively evaluated. Iodine density (milligram/milliliter) and Z-effective values were compared quantitatively between head and neck squamous cell carcinoma and normal neck mucosa. The receiver operating characteristic area under the curve determined the diagnostic performance of the spectral data for local staging. We compared conventional CT images without and with iodine density and Z-effective images to determine its impact on local tumor staging. Primary head and neck squamous cell carcinoma showed higher mean iodine density (2.01 [SD, 0.26] mg/mL, P < .001) and Z-effective values (8.21 [SD, 0.36], P < .001). A high interobserver correlation was demonstrated for ROI measurements for both the control group (iodine density, κ = 0.71, and Z-effective values, κ = 0.78) and head and neck squamous cell carcinoma (iodine density, κ = 0.84, and Z-effective values, κ = 0.75) group. The area under the curve for iodine density and Z-effective values was 0.98 and 0.93, respectively. Optimal thresholds were identified as 1.58 mg/mL (95% CI, 1.45-1.71 mg/mL; P < .001; sensitivity = 1.0; specificity = .0.93) for iodine density and 8.08 (95% CI, 7.96-8.19; P < .001; sensitivity = 0.86; specificity = 0.93) for Z-effective values. Conventional CT with the addition of dual-layer spectral data (iodine density and Z-effective values) improved the accuracy of local tumor staging in 3 of 21 patients (14%) with head and neck squamous cell carcinoma compared with the criterion standard surgical staging/histopathology. Dual-layer spectral iodine density and Z-effective values provided increased quantitative and qualitative differentiation between upper aerodigestive head and neck squamous cell carcinoma and normal mucosa. Increased tissue differentiation improved the local tumor staging accuracy.

Three-dimensional ultrasound for knee osteophyte depiction: a comparative study to computed tomography

PurposeOsteophytes are common radiographic markers of osteoarthritis. However, they are not accurately depicted using conventional imaging, thus hampering surgical interventions that rely on pre-operative images. Studies have shown that ultrasound (US) is promising at detecting osteophytes and monitoring the progression of osteoarthritis. Furthermore, three-dimensional (3D) ultrasound reconstructions may offer a means to quantify osteophytes. The purpose of this study was to compare the accuracy of osteophyte depiction in the knee joint between 3D US and conventional computed tomography (CT).MethodsEleven human cadaveric knees were pre-screened for the presence of osteophytes. Three osteoarthritic knees were selected, and then, 3D US and CT images were obtained, segmented, and digitally reconstructed in 3D. After dissection, high-resolution structured light scanner (SLS) images of the joint surfaces were obtained. Surface matching and root mean square (RMS) error analyses of surface distances were performed to assess the accuracy of each modality in capturing osteophytes. The RMS errors were compared between 3D US, CT and SLS models.ResultsAverage RMS error comparisons for 3D US versus SLS and CT versus SLS models were 0.87 mm ± 0.33 mm (average ± standard deviation) and 0.95 mm ± 0.32 mm, respectively. No statistical difference was found between 3D US and CT. Comparative observations of imaging modalities suggested that 3D US better depicted osteophytes with cartilage and fibrocartilage tissue characteristics compared to CT.ConclusionUsing 3D US can improve the depiction of osteophytes with a cartilaginous portion compared to CT. It can also provide useful information about the presence and extent of osteophytes. Whilst algorithm improvements for automatic segmentation and registration of US are needed to provide a more robust investigation of osteophyte depiction accuracy, this investigation puts forward the potential application for 3D US in routine diagnostic evaluations and pre-operative planning of osteoarthritis.

Proton stopping power prediction based on dual-energy CT-generated virtual monoenergetic images.

The purpose of this work was to assess a proof of concept for a novel method for predicting proton stopping power ratios (SPRs) based on a pair of dual-energy CT generated virtual monoenergetic (VM) images. A rapid kV-switching dual-energy CT scanner was used to acquire Gemstone Spectral Imaging (GSI) and 120kV conventional single-energy CT (SECT) image data of the CIRS 062M phantom. The proposed method was applied to every possible pairing of VM images between 40 and 140keV to find the optimal energy pairs for SPR prediction in lung tissue, soft tissue, and bone. The predicted SPRs were compared against SPRs predicted from the SECT data using the conventional SECT-based method. The impact of different scan and reconstruction parameters was also investigated. The SPR residual root mean square errors (RMSE) yielded by the optimal pairs were 7.2% for lung tissue, 0.4% for soft tissue, and 0.8% for bone. While no direct comparison could be made to other DECT-based methods for SPR prediction, as these methods could not be directly implemented on a fast kV-switching system, the SPR RMSEs for soft tissue and bone in Table 4 are comparable to RMSEs reported in the literature. For the conventional SECT-based method, the SPR RMSEs were 5.9% for lung tissue, 0.9% for soft tissue, and 5.1% for bone. The proposed method is a valid alternative to, and has the potential to improve upon, the conventional SECT-based method for predicting SPRs. The formalism used in the method is applied directly, with no approximations made on our part, and requires neither prior knowledge of the spectra nor calibration with a phantom. This work presents a way of optimizing the proposed method for a specific scanner by determining the optimal energy pairs to use as input and demonstrates the method's robustness to different levels of ASiR-V, reconstruction kernels, and dose levels.