Concentration Of Contrast Medium Research Articles

Influence of Contrast Media Temperature and Concentration on Patient Comfort and Safety in Computed Tomography: CATCHY II Trial.

Previous research on the necessity to reduce the viscosity of contrast media (CM) by either prewarming CM before injection during computed tomography (CT) or by using less concentrated CM has yielded conflicting results. In addition, there is limited evidence on patient comfort. The aim of the study was to examine if prewarming CM, with varying CM concentrations, is superior to CM at room temperature, with respect to patient comfort and safety in CT. All elective patients scheduled for contrast-enhanced CT scans at Maastricht University Medical Center+ between October 27, 2021 and October 31, 2022 were eligible for inclusion when a questionnaire evaluating patient comfort was completed. This 1-year period was divided into 4 intervals (4 groups): group 1 (370 mg I/mL, 37°C), group 2 (370 mg I/mL, room temperature), group 3 (300 mg I/mL, 37°C), and group 4 (300 mg I/mL, room temperature). All CT scans were performed using state of the art equipment (Siemens Healthineers; SOMATOM Force and SOMATOM Definition AS, Forchheim, Germany). Contrast media injections were performed using a dual-head power injector (Stellant; Bayer Healthcare, Berlin, Germany) and individualized to body weight and/or tube voltage, depending on the CM protocols. After the CT scan, patients completed a questionnaire covering the primary outcomes comfort, pain, and adverse events such as feelings of heat, nausea, vomiting, itchiness, urticaria, difficulty breathing, dizziness, goosebumps, or an odd taste. Technicians were asked to report any adverse events, including extravasation and allergic-like reactions. The secondary outcome involved attenuation (in Hounsfield unit, HU), which was evaluated by assessing the HU of the coronary arteries for vascular CT, and liver enhancement in portal venous CT. The Kruskal-Wallis test was used for continuous scale outcomes and χ2 tests for examining adverse events. Results showed no significant differences examining comfort score (P = 0.054), pain sensation (P = 0.469), extravasation (P = 0.542), or allergic-like reaction (P = 0.253). Significant differences among the 4 groups were found with respect to heat sensation and dizziness (P = 0.005 and P = 0.047, respectively), showing small effect sizes. All other adverse effects showed no significant results. No significant differences were observed in coronary attenuation among the 4 groups in coronary CT angiography (P = 0.113). When analyzing attenuation in portal venous CT scans, significant differences were found among the 4 groups (P = 0.008). Administrating prewarmed CM is nonsuperior compared with CM at room temperature in relation to patient comfort and safety, regardless of CM concentration. These findings suggest that prewarming CM before usage is unnecessary, which will improve the efficiency of daily clinical workflow and brings environmentally friendly benefits.

Estimating cardiac output from coronary CT angiography: an individualized compartment model in comparison to the Stewart-Hamilton method.

Attenuation is correlated with the concentration of contrast medium (CM) in the arteries. The cardiac output (CO) affects the concentration of CM in the circulatory system; therefore, CO affects the time-density curve (TDC). Thus, estimating CO using TDC from test-bolus images acquired in computed tomography (CT) is possible. In this study, we compare two methods of estimating CO, namely, an individualized mathematical compartment model, integrating patient, contrast, and scanning factors with TDC, and the Stewart-Hamilton method based on the area under the curve of the TDC. Attenuation in the aorta was measured during test-bolus in 40 consecutive patients with a clinical indication for coronary CT angiography (CCTA). Each participant underwent cardiac magnetic resonance imaging following CCTA to validate the estimated CO. The individual compartment model used TDC in conjunction with scanning and patient-specific parameters to estimate the concentration of CM and CO over time. This was compared to the CO calculated from the area under the curve using the Stewart-Hamilton method. Both CO estimated with our individualized compartment model (r = 0.66, p < 0.01) and the Stewart-Hamilton method (r = 0.53, p < 0.01) were moderately correlated with CO measured with cardiac MRI. Body surface area (BSA) and time to peak (TTP) affected the accuracy of our model. Lower BSA resulted in overestimation, and lower TTP resulted in CO underestimation, respectively. We found no gender-specific difference in the accuracy of our model when correcting for BSA. The Stewart-Hamilton method performed better with a more complete TDC, whereas the compartment model performed better overall with a partial TDC. The TDC acquired in CCTA allows for CO estimation. Both the Stewart-Hamilton method and our mathematical compartment model show moderate correlation when applied to our data, although each method has its strengths and limitations. If the majority of the TDC is known, the Stewart-Hamilton method may be more reliable, but an individual compartment model is preferable when there are insufficient data points in the TDC. Regardless, both methods can potentially increase the diagnostic information acquired from a CCTA, which is increasingly recommended in clinical guidelines.

A new modified technique of dynamic CT myelography to detect dural tears in spontaneous intracranial hypotension

We propose a modified dynamic CT-myelography technique for patients with fast CSF leaks caused by ventral dural tears in order to reduce radiation exposure and complications. A fluoroscopy-guided lumbar puncture using an epidural anesthesia kit replaces a CT-guided lumbar puncture, and a smaller volume of less concentrated contrast media is used. This approach has advantages, including speeding up the procedure, reduced radiation exposure, and elimination of the risk of contrast injection into the epidural space.

The effectiveness of post-processing head and neck CT angiography using contrast enhancement boost technique.

This study aimed to investigate the potential of contrast enhancement (CE)-boost technique in the head and neck computed tomography (CT) angiography in terms of the objective and subjective image quality. Consecutive patients who underwent head and neck CT angiography between May 2022 and July 2022 were included. The CE-boost images were generated by combining the subtracted iodinated image and contrast-enhanced image. The objective image analysis was compared for each image with and without CE-boost technique using the CT attenuation, image noise, signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), and image sharpness (full width at half width maximum, FWHM). The subjective image analysis was evaluated by two independent experienced radiologists in the following aspects: the overall image quality, motion artifact, vascular delineation, and vessel sharpness. A total of 65 patients (mean age, 59.48 ± 13.71 years; range, 24-87 years; 36 women) were included. The CT attenuation of the vertebrobasilar arteries was significantly (p < 0.001) higher in the images obtained using CE-boost technique than in conventional images. Image noise was significantly (p < 0.001) lower for CE-boost images (6.09 ± 1.93) than for conventional images (7.79 ± 1.73). Moreover, CE-boost technique yielded higher SNR (64.43 ± 17.17 vs. 121.37 ± 38.77, p < 0.001) and CNR (56.90 ± 18.79 vs. 116.65 ± 57.44, p < 0.001) than conventional images. CE-boost resulted in shorter FWHM than conventional images (p < 0.001). Higher subjective image quality scores were also demonstrated by the CE-boost than images without CE-boost technique. In both objective and subjective image analysis, the CE-boost technique provided higher image quality without increasing the flow rate and concentration of contrast media in the head and neck CT angiography. Furthermore, the vessel completeness and delineation were superior in CE-boost images than in conventional images.

A comparison of the use of contrast media with different iodine concentrations for enhanced computed tomography.

Objective: In this study, we compared the enhancement of blood vessels and liver parenchyma on enhanced computed tomography (CT) of the upper abdomen with two concentrations of contrast media (400 and 300mg I/mL) based on similar iodine delivery rate (IDR) of 0.88 and 0.9g I/s and iodine load of 450mg I/kg. Methods: We randomly assigned 160 patients into two groups: iomeprol 400mg I/mL (A group) and iohexol 300mg I/mL (B group). The CT attenuation values of the main anatomical structures in the two groups with different scanning phases were measured and the image quality of the two groups was analyzed and compared. The peak pressure and local discomfort (including fever and pain) during contrast medium injection were recorded. Results: The mean attenuation value of the abdominal aorta was 313.6 ± 29.6 in the A group and 322.4 ± 30.1 in the B group during the late arterial phase (p = 0.8). Meanwhile, the mean enhancement values of the portal vein were 176.2 ± 19.3 and 165.9 ± 24.5 in the A and B groups, respectively, during the portal venous phase (p = 0.6). The mean CT values of liver parenchyma were 117.1 ± 15.3 and 108.8 ± 18.7 in the A and B groups, respectively, during the portal venous phase (p = 0.9). There was no statistical difference in image quality, peak injection pressure (psi), and local discomfort between the two groups (p > 0.05). Conclusion: When a similar IDR and the same iodine load are used, CT images with different concentrations of contrast media have the same subjective and objective quality, and can meet the diagnostic needs.

Radiation Protection Device Composite of Epoxy Resin and Iodine Contrast Media for Low-Dose Radiation Protection in Diagnostic Radiology

Radiation protection in radiology is important because radiation may cause harm to the human body. The equipment for radiation protection is essential to ensure safe operations. Currently, there is widespread research on lead-free radiation shielding material. The aim of this research was to study lead-free material containing epoxy and iodine contrast media that was easy to form, low in cost, and environmentally friendly. The results showed that 2-cm material thickness with a concentration of 20% iodine had the greatest properties of radiation attenuate in the peak potential applied at technique 60-120 kVp, but the structure and strength of the shielding materials were decreased in accordance with increasing concentrations of iodine contrast media. It can be concluded that the lead-free epoxy radiation-shielding materials are able to absorb radiation at energy levels of 60-120 kVp. However, with improvement on homogeneity in the future, it could be used as a refractory shielding material in the radiology department.

A feasibility study of different GSI noise indexes and concentrations of contrast medium in hepatic CT angiography of overweight patients: image quality, radiation dose, and iodine intake.

To conduct a comparative study of image quality, radiation dose, and iodine intake in hepatic computed tomographic angiography (CTA) of overweight patients with different Gemstone Spectral Imaging (GSI) noise indexes combined with different concentrations of contrast medium. Ninety patients with a body mass index of ≥ 25kg/m2 were divided into three groups (A, B and C), each with 30 patients. The three groups underwent hepatic CTA with different NI of 7, 11 and 15, respectively, and were injected with different iodine concentrations of 370, 350 and 320mgI/mL, respectively. Five sets of images at 40-60keV (interval, 5keV) were reconstructed in each group. The CT value, image noise, contrast-to-noise ratio (CNR) and subjective score of the hepatic artery and vein, and portal vein in different monochromatic image sets were analyzed to select the optimal energy level in each group. The differences in CT value, image noise, CNR and a subjective score of hepatic artery and vein, portal vein in the optimal monochromatic images among the three groups were compared, the volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded, and the effective dose and iodine intake were calculated. The 40keV was determined to be the optimal energy level for the monochromatic image sets in each group. No significant group differences were noted in the CT value, image noise, CNR, and subjective image scores of the hepatic artery and vein, and portal vein for the optimal monochromatic images (P > 0.05). Compared with group A, the effective dose and iodine intake in group B were reduced by 50.18% and 9.3%, and by 58.12% and 14.23% in group C, respectively. A low-concentration contrast medium combined with a high-noise GSI index in hepatic CTA of overweight patients can reduce the radiation dose and iodine intake while ensuring image quality.

The use of the gold compound (AuCl4) solution as an alternative contrast medium for iodine in computed tomography (CT-Scan) imaging

In computerized tomography (CT-Scan), iodine solution was used as a contrast medium to improve imaging. But the iodine solution has different side effects for patients. In the present work, one of the gold compounds AuCl4 was used as an alternative contrast agent. The study used rabbits in an in vivo method to examine both the organs of the heart and the kidneys. Hounsfield unit (HU) values from computed tomography of rabbit and kidney angiography findings were found and compared with HU values for iodine contrast medium. Iodine solution is the only contrast medium currently used in the present study, gold tetrachloride (AuCl4) solution has been chosen as an alternative contrast medium in computed tomography scanning (CT-scan). It was found that using AuCl4 solution as an alternative contrast medium in rabbits enhanced the CT-scan imaging in the resolution and increasing the of heart and kidney organs in comparison with the iodine compound without any side effects. Rabbit’s heart and kidney were selected to study the effect of using 1.4 M iodine solution and 0.1 M AuCl4 as an alternative contrast medium in CT-scan. The HU value for the heart has 53 HU when used high concentration of Iodine complex, while the HU value at low concentration of alternative contrast medium of 0.1 M of gold compound has 50.5. The same results were found in the kidney organ. From these results, the resolution of the CT image is good and cleared when an alternative contrast medium (AuCl4) used. We can conclude that the alternate contrast medium for AuCl4 solution has high HU values for both heart and kidney compared to iodine solution.

Can magnetic resonance imaging after cranioplasty using titanium mesh detect brain tumors?

This study determined the dependence of the concentration and position of contrast-enhanced tumors on the radio frequency (RF)-shielding effect of titanium mesh using the contrast-to-noise ratio (CNR) in magnetic resonance imaging (MRI). A phantom was constructed by filling a plastic container with manganese chloride tetrahydrate and agar. Four cellophane cylindrical containers were arranged from the end of the plastic container, and the brain tumor model was filled with gadobutrol diluted with NaCl, with molarity values of 0.2-1.0mmol/L. The titanium mesh board was set on the left side of the phantom. Images were acquired using a 1.5-T MRI as well as two-dimensional spin-echo (2D SE) and three-dimensional fast spoiled gradient echo (3D FSPGR) sequences. CNR was calculated using the signal intensity values of the tumor model, surrounding area of the brain model, and background noise. Furthermore, the fractional change in CNR was calculated using values of CNR with and without the mesh. Moreover, a profile of CNR was created. The fractional change in CNR decreased at the brain tumor positions present near the mesh and at a contrast medium concentration of approximately ≤ 0.5mmol/L in 2D SE and ≤ 0.25mmol/L in 3D FSPGR. According to the CNR profiles, directly under the mesh, almost all contrast concentrations in 2D SE was unrecognizable; however, at a concentration of ≥ 0.5 mmol/L in 3D FSPGR was recognizable.

Stent imaging on a clinical dual-source photon-counting detector CT system-impact of luminal attenuation and sharp kernels on lumen visibility.

To assess the impact of scan modes and reconstruction kernels using a novel dual-source photon-counting detector CT (PCD-CT) on lumen visibility and sharpness of different stent sizes. A phantom containing six balloon-expandable stents (2.5 to 9 mm diameter) in silicone tubing was scanned on a PCD-CT with standard (0.6 mm and 0.4 mm thicknesses) and ultra-high-resolution (0.2 mm thickness) modes. With the use of increasing contrast medium concentrations, densities of 0, 200, 400, and 600 HU were achieved. Standard-resolution scans were reconstructed using increasing sharpness kernels, using both polyenergetic quantitative soft tissue "conventional" ((Qr40c(0.6 mm), Qr40c(0.4 mm), Qr72c(0.2 mm)) and vascular (Bv) virtual monoenergetic reconstructions (Bv44m(0.4 mm), Bv60m(0.4 mm)) at 70 keV. In-stent lumen visibility, sharpness (max. ΔHU of the stent measured in profile plots), and in-stent noise (standard deviation of HU) were measured. In-stent lumen visibility was highest for Qr72c(0.2 mm) (86.5 ± 2.8% to 88.3 ± 2.6%) and in Bv60m(0.4 mm) reconstructions (77.3 ± 2.9 to 82.7 ± 2.5%). Lumen visibility was lowest in the smallest stent (2.5 mm) ranging from 54.1% in Qr40c(0.6 mm) to 74.1% in Qr72c(0.2 mm) and highest in the largest stent (9 mm) ranging from 93.8% in Qr40c(0.6 mm) to 99.1% in the Qr72c(0.2 mm) series. Lumen visibility decreased by 2.1% for every 200-HU increase in lumen attenuation. Max. ΔHU between stents and stent lumen was highest in Qr72c(0.2 mm) (ΔHU 892 ± 504 to 1526 ± 517) and Bv60m(0.4 mm) series (ΔHU 480 ± 357 to 1030 ± 344). Improvement of lumen visibility and sharpness in UHR and Bv60m(0.4 mm) series was strongest in smaller stent sizes. UHR acquisition mode and sharp reconstruction kernels on a novel PCD-CT system significantly improve in-stent lumen visibility and sharpness-especially for smaller stent sizes. • In-stent lumen visibility and sharpness of stents significantly improve using sharp reconstruction kernels (Bv60) and ultra-high-resolution mode in photon-counting detector computed tomography. • The observed improvement of stent-lumen visibility was highest in smaller stent sizes.

Comparing feasibility of different tube voltages and different concentrations of contrast medium in coronary CT angiography of overweight patients.

To compare image quality, radiation dose, and iodine intake of coronary computed tomography angiography (CCTA) acquired by wide-detector using different tube voltages and different concentrations of contrast medium (CM) for overweight patients. A total of 150 overweight patients (body mass index≥25 kg/m2) who underwent CCTA are enrolled and divided into three groups according to scan protocols namely, group A (120 kVp, 370 mgI/ml CM); group B (100 kVp, 350 mgI/ml CM); and group C (80 kVp, 320 mgI/ml CM). The CT values, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure-of-merit (FOM) of all images are calculated. Images are subjectively assessed using a 5-point scale. In addition, the CT dose index volume (CTDIvol) and dose length product (DLP) of each patient are recorded. The effective radiation dose (ED) is also calculated. Above data are then statistically analyzed. The mean CT values, SNR, CNR, and subjective image quality of group A are significantly lower than those of groups B and C (P < 0.001), but there is no significant difference between groups B and C (P > 0.05). FOMs show a significantly increase trend from group A to C (P < 0.001). The ED values and total iodine intake in groups B and C are 30.34% and 68.53% and 10.22% and 16.85% lower than those in group A, respectively (P < 0.001). The lower tube voltage and lower concentration of CM based on wide-detector allows for significant reduction in iodine load and radiation dose in CCTA for overweight patients comparing to routine scan protocols. It also enhances signal intensity of CCTA and maintains image quality.

Reduced Iodinated Contrast Media Administration in Coronary CT Angiography on a Clinical Photon-Counting Detector CT System: A Phantom Study Using a Dynamic Circulation Model.

The aim of this study was to evaluate strategies to reduce contrast media volumes for coronary computed tomography (CT) angiography on a clinical first-generation dual-source photon-counting detector (PCD)-CT system using a dynamic circulation phantom. Coronary CT angiograph is an established method for the assessment of coronary artery disease that relies on the administration of iodinated contrast media. Reduction of contrast media volumes while maintaining diagnostic image quality is desirable. In this study, a dynamic phantom containing a 3-dimensional-printed model of the thoracic aorta and coronary arteries was evaluated using a clinical contrast injection protocol with stepwise reduced contrast agent concentrations (100%, 75%, 50%, 40%, 30%, and 20% contrast media content of the same 50 mL bolus, resulting in iodine delivery rates of 1.5, 1.1, 0.7, 0.6, 0.4 and 0.3 gl/s) on a first-generation, dual-source PCD-CT. Polychromatic images (T3D) and virtual monoenergetic images were reconstructed in the range of 40 to 70 keV in 5-keV steps. Attenuation and noise were measured in the coronary arteries and background material and the contrast-to-noise ratio (CNR) were calculated. Attenuation of 350 HU and a CNR of the reference protocol at 70 keV were regarded as sufficient for simulation of diagnostic purposes. Vessel sharpness and noise power spectra were analyzed for the aforementioned reconstructions. The standard clinical contrast protocol (bolus with 100% contrast) yielded diagnostic coronary artery attenuation for all tested reconstructions (>398 HU). A 50% reduction in contrast media concentration demonstrated sufficient attenuation of the coronary arteries at 40 to 55 keV (>366 HU). Virtual monoenergetic image reconstructions of 40 to 45 and 40 keV allowed satisfactory attenuation of the coronary arteries for contrast concentrations of 40% and 30% of the original protocol. A reduction of contrast agent concentration to 20% of the initial concentration provided insufficient attenuation in the target vessels for all reconstructions. The highest CNR was found for virtual monoenergetic reconstructions at 40 keV for all contrast media injection protocols, yielding a sufficient CNR at a 50% reduction of contrast agent concentration. Using virtual monoenergetic image reconstructions at 40 keV on a dual-source PCD-CT system, contrast media concentration could be reduced by 50% to obtain diagnostic attenuation and objective image quality for coronary CT angiography in a dynamic vessel phantom. These initial feasibility study results have to be validated in clinical studies.

Deep learning reconstruction allows for usage of contrast agent of lower concentration for coronary CTA than filtered back projection and hybrid iterative reconstruction.

The demand for homogeneous and higher vascular contrast enhancement is critical to provide an appropriate interpretation of abnormal vascular findings in coronary computed tomography angiography (CTA). To evaluate the effect of various contrast media concentrations (Iohexol-370, Iohexol-300, Iohexol-240) and image reconstructions (filtered back projection [FBP], hybrid iterative reconstruction [IR], and deep learning reconstruction [DLR]) on coronary CTA. A total of 63 patients referred for coronary CTA between July and October 2021 were enrolled in this prospective study, and they randomly received one of three contrast media. CTA images were reconstructed with FBP, hybrid IR, and DLR. The CT attenuation, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated for all three images. The images were subjectively evaluated by two radiologists in terms of overall image quality, artifacts, image noise, and vessel wall delineation on a 5-point Likert scale. The application of DLR resulted in significantly lower image noise; higher CT attenuation, SNR, and CNR; and better subjective analysis among the three different concentrations of contrast media groups (P < 0.001). There was no significant difference in the CT attenuation of the left ventricle (P = 0.089) and coronary arteries (P = 0.072) between hybrid IR at Iohexol-300 and DLR at Iohexol-240. Furthermore, application of DLR to the Iohexol-240 significantly improved SNR and CNR; it achieved higher subjective scores compared with hybrid IR at Iohexol-300 (P < 0.001). We suggest that using DLR with Iohexol-240 contrast media is preferable to hybrid IR with Iohexol-300 contrast media in coronary CTA.

Impact of iodinated contrast media concentration on image quality for dual-energy CT and single-energy CT with low tube voltage settings.

Contrast-induced nephropathy (CIN) is an adverse reaction associated with the use of intravenous contrast media (CM). To investigate the impact of low tube voltage settings on single-energy computed tomography (SECT) and rapid kV switching dual-energy CT (DECT) with reduced concentrations of iodinated CM. A phantom containing four different concentrations of CM (original concentration CM, 20%, 40%, and 60% reductions) was scanned using SECT mode with varying tube voltages (70, 80, 100, and 120 kVp) and DECT mode through reconstructing monoenergetic energy (50 keV and 70 keV) images. ATCM system with different noise index (NI) settings were set, and the images were reconstructed using ASiR-V. Image quality were measured for individual phantom sizes and protocols and compared to a reference protocol for SECT of 120 kVp, NI = 18, threshold contrast enhancement ≥280 HU, and CNR ≥17. Tube voltage settings of 70 kVp together with 40% reduction in the iodinated CM is suitable for small phantom size, those of 80 kVp and 20% reduction is suitable for the medium and large sizes. This allows radiation doses to be reduced by 12%-30%. Values of CNR and contrast for DECT are better than those for SECT with the same NI setting. Diagnostic reference of image quality can be maintained by using SECT with lower tube voltage and DECT with reductions of iodinated CM concentration and radiation dose. Therefore, the NI setting can be increased when DECT is used to achieve a similar image quality.

Three-Dimensional Kidney-on-a-Chip Assessment of Contrast-Induced Kidney Injury: Osmolality and Viscosity.

Increased viscosity of concentrated contrast media (CM) in the renal tubules can perturb renal hemodynamics and have a detrimental effect on tubular epithelial cells. However, the effects of viscosity on contrast-induced nephropathy (CIN) remain poorly understood. Conventional in vitro culture studies do not reflect the rheological properties of CM. Therefore, we investigated the effects of CM viscosity on renal tubules using a kidney-on-a-chip and two different types of CM. Renal proximal tubule epithelial cells (RPTEC) were cultured in a three-dimensional microfluidic culture platform under bidirectional fluid shear stress. We treated the RPTEC with two types of CM: low- (LOCM, iopromide) and iso-osmolar contrast media (IOCM, iodixanol). Renal tubular cell injury induced by LOCM and IOCM was examined under different iodine concentrations (50–250 mgI/mL) and shear-stress conditions. LOCM showed a significant dose-dependent cytotoxic effect, which was significantly higher than that of IOCM under static and low-to-moderate shear stress conditions. However, high shear-stress resulted in reduced cell viability in IOCM; no difference between IOCM and LOCM was found under high shear-stress conditions. The cytotoxic effects were pronounced at a mean shear stress of 1 dyn/cm2 or higher. The high viscosity of IOCM slowed the fluid flow rate and augmented fluid shear-stress. We suggest an alternative in vitro model of CIN using the three-dimensional kidney-on-a-chip. Our results indicate a vital role of viscosity-induced nephrotoxicity under high shear-stress conditions, contrary to the findings of conventional in vitro studies.

Noise-optimized virtual monoenergetic imaging technology of the third-generation dual-source computed tomography and its clinical applications.

The third-generation dual-source computed tomography (DSCT) is among the most advanced imaging methods. It employs noise-optimized virtual monoenergetic imaging (VMI+) technology. It uses the frequency-split method to extract high-contrast image information from low-energy images and low-noise information from images reconstructed at an optimal energy level, combining them to obtain the final image with improved quality. This review is the first to summarize the results of clinical studies that primarily and recently evaluated the VMI+ technique based on tumor, blood vessel, and other lesion classification. We aim to assist radiologists in quickly selecting the appropriate energy level when performing image reconstruction for superior image quality in clinical work and providing several ideas for future scientific research of the VMI+ technique. Presently, VMI+ reconstruction is mostly used for images of various tumors or blood vessels, including coronary plaques, coronary stents, deep vein thromboses, pulmonary embolisms (PEs), active arterial hemorrhages, and endoleaks after endovascular aneurysm repair. In addition, VMI+ has been used for imaging children's heads, liver lesions, pancreatic lacerations, and reducing metal artifacts. Regarding the reconstruction at the optimal energy level, the VMI+ technique yielded a higher image quality than the pre-optimized virtual monoenergetic imaging (VMI) technique and single-energy CT. Moreover, either low concentrations of contrast medium or low iodine injection rates can be applied before VMI+ reconstruction at a low-energy level to reduce contrast agent-related kidney injury risk. After reconstructing an image at the optimal energy level, both the image's window width and level can also be adjusted to improve the image effect's reach and diagnosis suitability. To improve image quality and lesion-imaging clarity and reduce the use of contrast agents, VMI+ reconstruction technology has been applied clinically, in which the selection of energy level is the key to the whole reconstruction process. Our review summarizes these optimal levels for radiologists' reference and suggests new ideas for the direction of future VMI+ research.

In vitro CT visualization of the biopsy location by filling the core biopsy needle with contrast media.

BackgroundWhen performing computed tomography (CT)-guided biopsy procedures with non-disposable, automatic biopsy instruments, the actual course of the biopsy needle is not registered.PurposeTo evaluate the ability to visualize the sampling location after CT-guided biopsy in vitro using a novel method, where the space between the inner needle and the outer cannula in a core biopsy needle is filled with contrast media; and to compare the grade of visibility for two different concentrations of contrast media.Material and MethodsCore needle biopsies were performed in a tissue phantom using biopsy needles primed with two different iodine contrast media concentrations (140 mg I/mL and 400 mg I/mL). Commercially available needle-filling contraptions with sealing membranes were used to fill the needles. Each biopsy was imaged with CT, and the visibility was evaluated twice by three senior radiologists in a randomized order.ResultsThe presence of traces was confirmed after biopsy, almost without exception for both concentrations. The visibility was sufficient to determine the biopsy location in all observations with the 400 mg I/mL filling, and in 7/10 observations with the 140 mg I/mL filling. The grade of visibility of the trace and the proportion of the biopsy needle course outlined were higher with the 400 mg I/mL filling.ConclusionWith CT-guided biopsy in vitro, the sampling location can be visualized using a novel method of priming the biopsy needle with iodine contrast media, specifically highly concentrated contrast media.

A threshold volume of 10ml is suggested for detecting articular cartilage defects in equine carpal joints using CT arthrography: Ex vivo pilot study.

Computed tomographic arthrography (CTA) has been described as a method for detecting articular cartilage defects in equine carpal joints; however, published studies on the effects of contrast volume for lesion detection are currently lacking. The purpose of this prospective, experimental, pilot study was to determine a threshold volume of iodinated contrast for CTA of the antebrachiocarpal (ABC) and middle carpal (MC) joints for detection of articular cartilage surface defects. Articular cartilage defects were iatrogenically created in the surfaces of the ABC and MC joints of 20 equine cadaver limbs using arthroscopy. Unaltered articular surfaces within some joints acted as controls. Joints were imaged precontrast using multidetector CT. The ABC and MC joints were injected with a 150mg iodine/ml nonionic contrast medium, in 5ml increments from 5 to 50ml per joint with CT performed subsequent to each increment. Cartilage defects were measured grossly using a caliper. Detection (qualitative) and measurement (quantitative) of the defects were independently performed by two board-certified radiologists using medical imaging software. At each volume of contrast, the interrater reliability for gross examination and the two observers in the detection of a defect was calculated (Gwet's AC1). Logistic mixed-effects models of selected volumes, 0, 5, 10, 15, and 50ml, demonstrated that at 10ml contrast and above, no statistically significant difference between either observer and gross examination for defect detection was identified for either joint. Findings supported using a dose of 10ml for 150mg iodine/ml concentration contrast media when performing CTA of equine carpal joints.

Effect of Lowering Tube Potential and Increase Iodine Concentration of Contrast Medium on Radiation Dose and Image Quality in Computed Tomography Pulmonary Angiography Procedure: A Phantom Study

The aim of the study was to examine the effect of lowering tube potential and increase iodine concentration on image quality and radiation dose in computed tomography pulmonary angiography procedure. The pulmonary arteries were simulated by three syringes. The syringes were filled with 1:10 diluted solutions of 300 mg, 350 mg and 370 mg of iodine per millilitre concentration in three water-filled phantoms simulating thin, intermediate and thick patients. The phantoms were scanned at 80 kVp, 110 kVp and 130 kVp and 0.6 second rotation time using a 16 slice computed tomography (CT) scanner. The tube current was either fixed at 80, 100, 200, 250 and 300 mA or automatically adjusted with quality reference tube current-time product (mAsQR). In comparison with 130 kVp, images acquired at 80 kVp and 110 kVp, respectively, showed 76.2% to 99% and 19% to 26% enhancement in CT attenuation of iodinated contrast material. A volume CT dose index (CTDIvol) reduction by 35.3% was attained in small phantom with the use of 80 kVp, while in the medium phantom, a CTDIvol reduction by 29.9% was attained with the use of 110 kVp instead of 130 kVp. In light of the above, lowering tube potential and increase iodinated CM could substantially reduce the dose to small-sized adults and children.&#x0D; Keywords: Angiography; Computed tomography; Low tube potential; Iodinated contrast medium; Radiation dose

TAGUCHI-BASED OPTIMIZATION OF HEAD AND NECK CT ANGIOGRAPHY: IN-VIVO ENHANCED TRIGGERED TIMING FOR 600 PATIENTS

The Taguchi-based optimization of head and neck CT angiography (CTA) using in-vivo enhanced triggered timing for 600 patients was accomplished in this study. A total of 600 patients were categorized into three (test, verification, and implementation groups with 360, 120, and 120 patients, respectively). The patients in the test group were randomly assigned into 18 sub-groups according to Taguchi L[Formula: see text](2[Formula: see text]) orthogonal array for optimizing factor combinations of head and neck CTA. The signal-to-noise ratio was defined as a high LRA/US ratio (both left and right arterial pressure divided by upper sinuses’ one) and low stdev. The seven factors of CTA were: (A) left- or right-hand injection; (B) tube current, mA; (C) kilovoltage peak, kVp; (D) contrast media concentration; (E) FOV; (F) flow rate of contrast media; and (G) rotation time for one CTA loop. With the Taguchi unique organization, 18 sub-groups (each containing 20 patients’ real LRA/US ratios) could cover 1458 cases and provide the appropriate reliability. The optimal factor combination was identified as follows: (A) left-hand injection, (B) tube current of 280[Formula: see text]mA, (C) 100[Formula: see text]kVp, (D) contrast media concentration of 60%, (E) FOV of 250[Formula: see text]mm, (F) contrast media flow rate of 4.0[Formula: see text]ml/s, and (G) rotation time for one CTA loop of 0.9[Formula: see text]s. The optimal suggestion was validated in the verification group with 120 patients and applied to the implementation group with 120 patients. The successful factor combination is instrumental in defining a standard protocol for medical staff in deriving the maximal LRA/US value ([Formula: see text]) of head and neck CTA.