Dual-source DECT Research Articles

Multiparametric detection and outcome prediction of pancreatic cancer involving dual-energy CT, diffusion-weighted MRI, and radiomics

BackgroundThe advent of next-generation computed tomography (CT)- and magnetic resonance imaging (MRI) opened many new perspectives in the evaluation of tumor characteristics. An increasing body of evidence suggests the incorporation of quantitative imaging biomarkers into clinical decision-making to provide mineable tissue information. The present study sought to evaluate the diagnostic and predictive value of a multiparametric approach involving radiomics texture analysis, dual-energy CT-derived iodine concentration (DECT-IC), and diffusion-weighted MRI (DWI) in participants with histologically proven pancreatic cancer.MethodsIn this study, a total of 143 participants (63 years ± 13, 48 females) who underwent third-generation dual-source DECT and DWI between November 2014 and October 2022 were included. Among these, 83 received a final diagnosis of pancreatic cancer, 20 had pancreatitis, and 40 had no evidence of pancreatic pathologies. Data comparisons were performed using chi-square statistic tests, one-way ANOVA, or two-tailed Student’s t-test. For the assessment of the association of texture features with overall survival, receiver operating characteristics analysis and Cox regression tests were used.ResultsMalignant pancreatic tissue differed significantly from normal or inflamed tissue regarding radiomics features (overall P < .001, respectively) and iodine uptake (overall P < .001, respectively). The performance for the distinction of malignant from normal or inflamed pancreatic tissue ranged between an AUC of ≥ 0.995 (95% CI, 0.955–1.0; P < .001) for radiomics features, ≥ 0.852 (95% CI, 0.767–0.914; P < .001) for DECT-IC, and ≥ 0.690 (95% CI, 0.587–0.780; P = .01) for DWI, respectively. During a follow-up of 14 ± 12 months (range, 10–44 months), the multiparametric approach showed a moderate prognostic power to predict all-cause mortality (c-index = 0.778 [95% CI, 0.697–0.864], P = .01).ConclusionsOur reported multiparametric approach allowed for accurate discrimination of pancreatic cancer and revealed great potential to provide independent prognostic information on all-cause mortality.

Comparison of True and Virtual Non-Contrast Images of Liver Obtained with Single-Source Twin Beam and Dual-Source Dual-Energy CT

To assess the magnitude of differences between attenuation values of the true non-contrast image (TNC) and virtual non-contrast image (VNC) derived from twin-beam dual-energy CT (tbDECT) and dual-source DECT (dsDECT). This retrospective study included 62 patients who underwent liver dynamic DECT with tbDECT (n = 32) or dsDECT (n = 30). Arterial VNC (AVNC), portal VNC (PVNC), and delayed VNC (DVNC) were reconstructed using multiphasic DECT. Attenuation values of multiple intra-abdominal organs (n = 11) on TNCs were subsequently compared to those on multiphasic VNCs. Further, we investigated the percentage of cases with an absolute difference between TNC and VNC of ≤ 10 Hounsfield units (HU). For the mean attenuation values of TNC and VNC, 33 items for each DECT were compared according to the multiphasic VNCs and organs. More than half of the comparison items for each DECT showed significant differences (tbDECT 17/33; dsDECT 19/33; Bonferroni correction p < 0.0167). The percentage of cases with an absolute difference ≤ 10 HU was 56.7%, 69.2%, and 78.6% in AVNC, PVNC, and DVNC in tbDECT, respectively, and 70.5%, 78%, and 78% in dsDECT, respectively. VNCs derived from the two DECTs were insufficient to replace TNCs because of the considerable difference in attenuation values.

Evaluation of Hypervascular Focal Liver Lesions Utilizing Virtual Monoenergetic Images from Third-Generation Dual-Source Dual-Energy Computed Tomography

Abstract Objectives The purpose of our study was to evaluate the virtual monochromatic imaging in detecting hypervascular focal liver lesions in the late arterial phase with third-generation dual-source dual-energy computed tomography and to assess its image quality. Materials and Methods In our study, 80 patients were included. Contrast-enhanced images in the late arterial phase (in the dual-energy mode) were acquired and were post-processed in Syngo, via workstation, using Monoenergetic + software. Five sets of images, one polychromatic energy image (corresponding to 120 kVp single-energy image) and four virtual monoenergetic image (VMI) sets at 40, 50, 60, and 70 keV levels, were generated. All these images were analyzed both objectively and subjectively. The attenuation values were measured, and the contrast-to-noise ratio (CNR) of liver and tumor were measured and compared objectively in each dataset. Image noise, image contrast, and diagnostic confidence for liver lesion detection were analyzed subjectively using a five-point scale system. Statistical analysis was performed using Kolmogorov–Smirnov, analysis of variance, and Kruskal–Wallis tests. Results Among the VMI, maximum image noise was observed in the 40 keV image, with a gradual reduction in the image noise being noted with an increase in the VMI energy. The CNR of the hepatic parenchyma and the tumor gradually increased with a reduction in VMI energy from 70 to 40 keV. On subjective analysis, image contrast and image noise were observed to be more in low VMI datasets. In lesion detection, diagnostic confidence with an excellent confidence level was observed with a decrease in VMI energy. Conclusion VMI datasets of 40 to 70 keV from third-generation dual-source DECT provide superior diagnostic accuracy for detecting hypervascular liver lesions. Considering the image noise and lesion detection rate among the VMI datasets, 60 keV VMI is the most helpful dataset for increased liver lesion detection with good image quality.

Side-by-side evaluation of virtual non-contrast and post-contrast images improves detection of clinically significant urolithiasis on single-phase split bolus dual-energy CT urography.

Studies show insufficient sensitivity of virtual non-contrast (VNC) reconstructions for stone detection in dual-energy CT urography (DE-CTU). The aim of this study was to investigate if side-by-side-evaluation of both VNC and post-contrast images could increase the sensitivity of single-phase split bolus DE-CTU. Consecutive patients with haematuria who underwent split bolus DE-CTU on the same dual-source DE-CT scanner were retrospectively enrolled in the study. Intravenous furosemide and oral hydration were employed. Two readers, independently and then jointly in two separate sessions, recorded the location and the longest axial stone diameter on three randomised sets of images: separate VNC and post-contrast images, and side-by-side-reconstructions. True non-contrast (TNC) images served as the standard of reference. A total of 83 urinary stones were detected on TNC images. Independent reader side-by-side-evaluation of VNC and post-contrast images yielded higher stone detection sensitivity (76 and 84%, respectively) compared to evaluation of only VNC (71 and 81%, respectively) or post-contrast images (64 and 80%, respectively). The sensitivity of joint reader evaluation of side-by-side-images reached almost 86% and was not significantly different from TNC images (p = 0.77). All stones larger than 3 mm were correctly detected by side-by-side-evaluation. Dose reduction of 55% could be achieved by omitting TNC scans. Side-by-side-VNC and post-contrast image evaluation enable detection of clinically significant urolithiasis on single-phase split bolus DE-CTU with significant dose reduction. This study shows that single-phase DE-CTU is feasible if VNC imaging is simultaneously utilised with post-contrast images.

Low-dose dual-energy CT for stone characterization: a systematic comparison of two generations of split-filter single-source and dual-source dual-energy CT.

To compare noise texture and accuracy to differentiate uric acid from non-uric acid urinary stones among four different single-source and dual-source DECT approaches in an ex vivo phantom study. Thirty-two urinary stones embedded in gelatin were mounted on a Styrofoam disk and placed into a water-filled phantom. The phantom was imaged using four different DECT approaches: (A) dual-source DECT (DS-DE); (B) 1st generation split-filter single-source DECT (SF1-TB); (C) 2nd generation split-filter single-source DECT (SF2-TB) and (D) 2nd generation split-filter single-source DECT using serial acquisitions (SF2-TS). Two different radiation doses (3mGy and 6mGy) were used. Noise texture was compared by assessing the average spatial frequency (fav) of the normalized noise power spectrum (nNPS). ROC curves for stone classification were computed and the accuracy for different dual-energy ratio cutoffs was derived. NNPS demonstrated comparable noise texture among A, C, and D (fav-range 0.18-0.19) but finer noise texture for B (fav = 0.27). Stone classification showed an accuracy of 96.9%, 96.9%, 93.8%, 93.8% for A, B, C, D for low-dose, respectively, and 100%, 96.9%, 96.9%, 100% for routine dose. The vendor-specified cutoff for the dual-energy ratio was optimal except for the low-dose scan in D for which the accuracy was improved from 93.8 to 100% using an optimized cutoff. Accuracy to differentiate uric acid from non-uric acid stones was high among four single-source and dual-source DECT approaches for low- and routine dose DECT scans. Noise texture differed only slightly for the first-generation split-filter approach.

Virtual monochromatic reconstructions of dual energy CT in abdominal trauma: optimization of energy level improves pancreas laceration conspicuity and diagnostic confidence.

Pancreatic injury is associated with significant morbidity and mortality. Pancreatic lacerations can be challenging to identify as the pancreas is not scanned at peak enhancement in most trauma CT protocols. This study qualitatively and quantitively assessed pancreatic lacerations with virtual monoenergetic dual-energy CT (DE CT) to establish an optimal energy level for visualization of pancreatic lacerations. Institutional review board approval was obtained. We retrospectively examined 17 contrast-enhanced CT studies in patients with blunt trauma with MRCP, ERCP, or surgically proven pancreatic lacerations. All studies were performed in our Emergency Department from 2016 to 2019 with a 128 slice dual-source DE CT scanner. Conventional 120kVp and noise-optimized virtual monoenergetic imaging (VMI) datasets were created. VMI energy levels were constructed from 40 to 100keV in 10keV increments and analyzed quantitatively and qualitatively. Pancreatic laceration attenuation, background parenchymal attenuation, and noise were calculated. Qualitative assessment was performed by two independent readers. The optimal CNR for the assessment of pancreatic lacerations was observed at VMI-40 in comparison with standard reconstructions and the remaining VMI energy levels (p = 0.001). Readers reported improved contrast resolution, diagnostic confidence, and laceration conspicuity at VMI at 40keV (p = 0.016, p = 0.002, and p = 0.0012 respectively). However, diagnostic acceptability and subjective noise were improved on conventional polyenergentic images (p = 0.0006 and p = 0.001 respectively). Dual energy CT at VMI-40 maximizes the CNR of pancreatic laceration, improves diagnostic confidence, and increases laceration conspicuity.

Dual-Energy CT-Based Iodine Quantification in Liver Tumors – Impact of Scan-, Patient-, and Position-Related Factors

To quantify the contribution of lesion location and patient positioning, dual-energy approach, patient size, and radiation dose to the error of dual-energy CT-based iodine quantification (DECT-IQ) in liver tumors. A phantom with four liver lesions (diameter 15 mm; iodine concentration 0-5 mgI/mL) and two sizes was used. One lesion emulated a subdiaphragmatic lesion. Both sizes were imaged in dual-energy mode on (1) a dual-source DECT (DS-DE) at 100/Sn150 kV and (2) a single-source split-filter DECT (SF-DE) at AuSn120 kV at two radiation doses (8 and 12 mGy). Scans were performed at seven different vertical table positions (from -6 to + 6 cm from the gantry isocenter). Iodine concentration was repeatedly measured and absolute errors (errorabs) were calculated. Errors were compared using robust repeated-measures ANOVAs with post-hoc comparisons. A linear mixed effect model was used to determine the factors influencing the error of DECT-IQ. The linear mixed effect models showed that errors were significantly influenced by DECT approach, phantom size, and lesion location (all p < 0.001). The impact of lesion location on the error was stronger in SF-DE compared to DS-DE. Radiation dose did not significantly influence error (p = 0.22). When averaged across all setups, errorabs was significantly higher for SF-DE (2.08 ± 1.92 mgI/mL) compared to DS-DE (0.37 ± 0.29 mgI/mL) (all p < 0.001). Artefacts were found in the subdiaphragmatic lesion for SF-DE with significantly increased errorabs compared to DS-DE (p < 0.001). Errorabs was significantly higher in the large compared to the medium phantom for DS-DE (0.30 ± 0.23 mgI/mL vs. 0.43 ± 0.33 mgI/mL) and SF-DE (1.68 ± 1.99 vs. 2.36 ± 1.81 mgI/mL) (p < 0.001). The dual-energy approach, patient size, and lesion location modified by patient position significantly impacted DECT-IQ in simulated liver tumors.

Comparison of image quality and radiation doses between rapid kV-switching and dual-source DECT techniques in the chest

PurposeTo compare image quality and radiation doses for chest DECT acquired with dual-source and rapid-kV switching techniques. Materials and methodsOur institutional Review Board approved retrospective study included 97 patients (54 men, 43 women; 63 ± 14 years) who underwent contrast-enhanced chest DECT with both single source, rapid kV-switching (SS-DECT) and dual source (DS-DECT) techniques per standard of care departmental protocols. Reconstructed images from both scanners had identical section thickness and section interval for virtual monoenergetic and material decomposition iodine (MDI) images. Two thoracic radiologists independently evaluated all DECT for findings, quality of images, perfusion defects (MDI), and presence of artifacts. Radiation dose descriptor, size-specific dose estimates (SSDE), was recorded. Data were analyzed with Wilcoxon Signed Rank and Cohen’s Kappa tests. ResultsThere were no significant differences in patient weight or SSDE for the two DECT techniques (p > 0.06). Both radiologists reported no difference in lesion and artifact evaluation on the virtual monoenergetic images from either technique (p > 0.05). However, SS-DECT (in 63–71/97 patients) had substantial artifactual heterogeneity in pulmonary perfusion on MDI images compared to none on DS-DECT (p < 0.001). ConclusionDespite identical patients and associated radiation doses, there were substantial differences in material decomposition iodine images generated from SS-DECT and DS-DECT techniques. Pulmonary heterogeneity on MDI images from SS-DECT leads to artifactual areas of low perfusion and can confound interpretation of true pulmonary perfusion.

Dual-Source Dual-Energy CT Portal Venous Phase Abdominal CT Scans in Large Body Habitus Patients: Preliminary Observations on Image Quality and Material Decomposition.

Our objective was to evaluate image quality (IQ) and material decomposition in patients with large body habitus undergoing portal venous phase abdominal computed tomography (CT) scans on dual-source dual-energy CT (dsDECT) scanners. This retrospective analysis included 30 scans from consecutive patients (19 males/11 females, mean ± SD age = 55.3 ± 17.5 years, range = 27-87 years) with large body habitus (≥90 kg, mean ± SD weight = 105.4 ± 12.35, range = 91-145 kg) who underwent portal venous phase abdominal DECT examinations on dsDECT scanner between Jan 2015 and Dec 2015. Qualitative and quantitative evaluation of IQ of DECT data sets (blended, iodine, and virtual noncontrast images) was performed. The patients were categorized into 2 groups (group A, ≤104 kg; group B, >104 kg). The mean ± SD patient body weight in group A was 97.2 ± 4.5 kg (range = 91-104 kg) and 114.8 ± 11.7 kg (range = 104.3-145.2 kg) for patients in group B. The diagnostic acceptability of the blended images in patients > 104 kg was lower (3.6 vs 4, <3 in 4/14 vs 0/16, P = 0.03). The extension of visceral anatomy beyond DE field of view (DEFOV) was seen in 60% (28 organs in 18 patients), the most common organs being liver and spleen. The incidence of visceral organs outside DEFOV was significantly higher in patients > 104 kg (18 vs 10, P = 0.03). Outside the DEFOV, blended images demonstrated higher image noise (mean: 14.48, range = 10.09-26.83 vs mean: 9.5, range = 7.3-15.8) P < 0.001) and lower signal-to-noise ratio (mean: 4.15, range = 1.5-7.6 vs mean: 7.5, range = 4.2-9.9) P < 0.001), and material-specific information was not available in this region. Within the DEFOV, the IQ of iodine maps and virtual non-contrast images were diagnostically acceptable with diagnostic acceptability of 3 or greater in nearly all patients. A 40-cm transverse diameter cut-off provided a good predictor of extension of visceral anatomy outside the effective DEFOV. Dual-source DECT allows diagnostically acceptable IQ and material separation in patients with large body habitus with the major limitation of exclusion of patient anatomy and organs outside the effective dual-energy field of view.

Application of single- and dual-energy CT brain tissue segmentation to PET monitoring of proton therapy

The purpose of this work was to evaluate the ability of single and dual energy computed tomography (SECT, DECT) to estimate tissue composition and density for usage in Monte Carlo (MC) simulations of irradiation induced β+ activity distributions. This was done to assess the impact on positron emission tomography (PET) range verification in proton therapy.A DECT-based brain tissue segmentation method was developed for white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF). The elemental composition of reference tissues was assigned to closest CT numbers in DECT space (DECTdist). The method was also applied to SECT data (SECTdist). In a validation experiment, the proton irradiation induced PET activity of three brain equivalent solutions (BES) was compared to simulations based on different tissue segmentations. Five patients scanned with a dual source DECT scanner were analyzed to compare the different segmentation methods. A single magnetic resonance (MR) scan was used for comparison with an established segmentation toolkit. Additionally, one patient with SECT and post-treatment PET scans was investigated.For BES, DECTdist and SECTdist reduced differences to the reference simulation by up to 62% when compared to the conventional stoichiometric segmentation (SECTSchneider). In comparison to MR brain segmentation, Dice similarity coefficients for WM, GM and CSF were 0.61, 0.67 and 0.66 for DECTdist and 0.54, 0.41 and 0.66 for SECTdist. MC simulations of PET treatment verification in patients showed important differences between DECTdist/SECTdist and SECTSchneider for patients with large CSF areas within the treatment field but not in WM and GM. Differences could be misinterpreted as PET derived range shifts of up to 4 mm. DECTdist and SECTdist yielded comparable activity distributions, and comparison of SECTdist to a measured patient PET scan showed improved agreement when compared to SECTSchneider.The agreement between predicted and measured PET activity distributions was improved by employing a brain specific segmentation applicable to both DECT and SECT data.

Quantitative iodine content threshold for discrimination of renal cell carcinomas using rapid kV-switching dual-energy CT.

Determine iodine content threshold discriminating papillary renal cell carcinomas (pRCC) from complex cysts (CCs) using rapid kV-switching dual-energy CT (rsDECT). IRB-approved retrospective study of 72 consecutive patients with pathologic diagnosis of renal cell carcinoma, who underwent rsDECT from 2011 to 2015. Controls included consecutive patients with CC during same period. Iodine content of each pRCC (n=27) was measured on rsDECT workstation for arterial (n=15) or nephrographic phase (n=12), and compared to iodine content for clear cell renal cell carcinomas (ccRCC, n=46) and complex cysts (n=54). An optimal iodine content threshold was estimated using logistic regressions and Youden's J based on maximum specificity and sensitivity. Iodine threshold of 1.28mg/cc was optimal to discriminate between pRCCs and CCs for nephrographic phase (sens 1.0, spec 0.96, PPV 0.92, and NPV 1.0, AUC 0.997, acc 0.97, p<0.0001). Iodine threshold of 1.22mg/cc was the optimal cutoff value to discriminate between pRCCs and CCs in the arterial phase (sens 0.67, spec 0.97, PPV 0.91, NPV 0.85, AUC 0.76, and acc 0.84, p=0.006). The optimal threshold to discriminate between ccRCCs and pRCCs was 1.85mg/cc in the arterial phase (sens 0.87, spec 0.92, PPV 0.87, NPV 0.92, p<0001) and 2.71mg/cc in the nephrographic phase (sens 1.0, spec 1.0, PPV 1.0, NPV 1.0, p<0.0001). Quantitative iodine values on rsDECT discriminate between papillary RCC and complex cysts, and between papillary RCC and clear cell RCC, the former addressing an important clinical challenge particularly when an unenhanced series has not been performed. These rsDECT thresholds differ from values derived from dual-source DECT technology.

Extracting atomic numbers and electron densities from a dual source dual energy CT scanner: Experiments and a simulation model

Background and purposeDual energy CT (DECT) imaging can provide both the electron density ρe and effective atomic number Zeff, thus facilitating tissue type identification. This paper investigates the accuracy of a dual source DECT scanner by means of measurements and simulations. Previous simulation work suggested improved Monte Carlo dose calculation accuracy when compared to single energy CT for low energy photon brachytherapy, but lacked validation. As such, we aim to validate our DECT simulation model in this work. Materials and methodsA cylindrical phantom containing tissue mimicking inserts was scanned with a second generation dual source scanner (SOMATOM Definition FLASH) to obtain Zeff and ρe. A model of the scanner was designed in ImaSim, a CT simulation program, and was used to simulate the experiment. ResultsAccuracy of measured Zeff (labelled Z) was found to vary from −10% to 10% from low to high Z tissue substitutes while the accuracy on ρe from DECT was about 2.5%. Our simulation reproduced the experiments within ±5% for both Z and ρe. ConclusionsA clinical DECT scanner was able to extract Z and ρe of tissue substitutes. Our simulation tool replicates the experiments within a reasonable accuracy.

Improved dual‐energy material discrimination for dual‐source CT by means of additional spectral filtration

The use of additional spectral filtration for dual-energy (DE) imaging using a dual-source CT (DSCT) system was investigated and its effect on the material-specific DE(ratio) was evaluated for several clinically relevant materials. The x-ray spectra, data acquisition, and reconstruction processes for a DSCT system (Siemens Definition) were simulated using information provided by the system manufacturer, resulting in virtual DE images. The factory-installed filtration for the 80 kV spectrum was left unchanged to avoid any further reductions in tube output, and only the filtration for the high-energy spectrum was modified. Only practical single-element filter materials within the atomic number range of 40 < or = Z < or = 83 were evaluated, with the aim of maximizing the separation between the two spectra, while maintaining similar noise levels for high- and low-energy images acquired at the same tube current. The differences between mean energies and the ratio of the 140 and 80 kV detector signals, each integrated below 80 keV, were evaluated. The simulations were performed for three attenuation scenarios: Head, body, and large body. The large body scenario was evaluated for the DE acquisition mode using the 100 and 140 kV spectra. The DE(ratio) for calcium hydroxyapatite (simulating bone or calcifications), iodine, and iron were determined for CT images simulated using the modified and factory-installed filtration. Several filter materials were found to perform well at proper thicknesses, with tin being a good practical choice. When image noise was matched between the low- and high-energy images, the spectral difference in mean absorbed energy using tin was increased from 25.7 to 42.7 keV (head), from 28.6 to 44.1 keV (body), and from 20.2 to 30.2 keV (large body). The overlap of the signal spectra for energies below 80 keV was reduced from 78% to 31% (head), from 93% to 27% (body), and from 106% to 79% (large body). The DE(ratio) for the body attenuation scenario increased from 1.45 to 1.91 (calcium), from 1.84 to 3.39 (iodine), and from 1.73 to 2.93 (iron) with the additional tin filtration compared to the factory filtration. This use of additional filtration for one of the x-ray tubes used in dual-source DECT dramatically increased the difference between material-specific DE ratios, e.g., from 0.39 to 1.48 for calcium and iodine or from 0.28 to 1.02 for calcium and iron. Because the ability to discriminate between different materials in DE imaging depends primarily on the differences in DE ratios, this increase is expected to improve the performance of any material-specific DECT imaging task. Furthermore, for the large patient size and in conjunction with a 100/140 kV acquisition, the use of additional filtration decreased noise in the low-energy images and increased contrast in the DE image relative to that obtained with 80/140 kV and no additional filtration.

Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol

The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo.