Iodine dose optimization in portal venous phase virtual monochromatic images of the abdomen: Prospective study on rapid kVp switching dual energy CT

Noda, Yoshifumi; Goshima, Satoshi; Nakashima, Yuka; Miyoshi, Toshiharu; Kawai, Nobuyuki; Kambadakone, Avinash

doi:10.1016/j.ejrad.2019.108746

Cited by 16 publications

(5 citation statements)

References 15 publications

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“…This phenomenon may be attributed to the limitations associated with using a longer tube rotation time of rapid fast-switching kVp for DECT compared to SECT, which typically takes 0.5 seconds or more. This finding is consistent with previous studies by Goo HW, et al (5) and Noda Y, et al (21) . To address this, the low-voltage exposure time ratio was increased from 50 to 65%, resulting in predominant an accentuated CT number near the iodine k-edge.…”

Section: Signal (Hu) Noise (Sd) and Signal-to-noise Ratio (Snr)supporting

confidence: 94%

Comparison of radiation dose and image quality between fast kVp switching dual-energy CT and routine single-energy CT for whole abdomen at King Chulalongkorn Memorial Hospital

Khemkhangboon

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Abdominal computed tomography (CT) using a single energy protocol is a common imaging procedure in hospitals. As CT technology has continued to evolve, dual-energy protocols (DECT) have emerged as a new option. A spectral CT scanner with fast kVp switching was installed at King Chulalongkorn Memorial Hospital in 2017, and its clinical utility in emergency patients has not yet been studied. This study aims to compare the radiation dose and image quality between DECT and SECT in abdominal CT for emergency patients. The study retrospectively collected CT data from 130 standard-sized adult patients who underwent contrast-enhanced using the 256-slice MDCT. CT Contrast media was intravenously injected of iobitridol at a dose of 2.0 mL/kg with a flow rate of 2 mL/s through the median cubital vein. After the contrast medium was administered for 90 s, fast kVp-switching DECT (80/140 kVp,) and SECT (120 kVp) enhanced abdominal CT was performed. The scanning parameters for fast kVp-switching between 80 and 140-kVp were as follows: tube current, GSI Assist; detector collimation 80 x 0.625 mm; rotation speed 0.6 s; pitch factor 0.992:1. The scanning parameters for single-energy CT were as follows: 120 kVp, tube current 3D mA modulation; detector collimation 80 x 0.625 mm; rotation speed 0.5 s; pitch factor 0.992:1. The radiation dose was evaluated for both protocols in terms of CTDIvol. Objective analysis was performed by measuring the region of interest (ROI) at 5 abdominal structures: aorta, main portal vein, liver, spleen, and psoas muscle in order to evaluate signal (HU), noise (SD), and signal-to-noise ratio (SNR). Subjective image quality was evaluated by two radiologists who have similar experience in terms of diagnostic acceptability on a 4-point scale and image noise on a 3-point scale following the European Guidelines on Quality Criteria. There was no statistically significant difference in average CTDIvol between SECT (10.7?2.3 mGy) and DECT (10.3?2.8 mGy) (p>0.05). The objective image quality analysis indicated that DECT had significantly higher signal and noise values compared to SECT for all measured structures (p<0.05), but there was no significant difference in SNR except MPV between the two groups (p>0.05). The subjective image quality analysis showed no significant difference in diagnostic acceptability and image noise between SECT and DECT as evaluated by both radiologists (p>0.05). In conclusion, the fast kV switching DECT protocol used in this study provides similar objective image quality and equivalent subjective image quality with a similar level of radiation dose as SECT. Therefore, the results of this study could be implemented as a routine protocol in the emergency room to reduce patient radiation dose while maintaining image quality and accelerating patient diagnostic workflow.

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Section: Signal (Hu) Noise (Sd) and Signal-to-noise Ratio (Snr)supporting

confidence: 94%

Comparison of radiation dose and image quality between fast kVp switching dual-energy CT and routine single-energy CT for whole abdomen at King Chulalongkorn Memorial Hospital

Khemkhangboon

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“…While single-source rapid kilovoltage switching might be too slow regarding its offset between the scans dual source dual energy CT also might suffer due to its angular offset. Photon counting CT using dual contrast of iodine and gadolinium based contrast agents or gadolinium based contrast agents alone might become of interest in the future [ 23 , 24 ].…”

Section: Discussionmentioning

confidence: 99%

Spectral computed tomography angiography using a gadolinium-based contrast agent for imaging of pathologies of the aorta

Graf,

Gassert,

Marka

et al. 2024

Int J Cardiovasc Imaging

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Objectives Especially patients with aortic aneurysms and multiple computed tomography angiographies (CTA) might show medical conditions which oppose the use of iodine-based contrast agents. CTA using monoenergetic reconstructions from dual layer CT and gadolinium (Gd-)based contrast agents might be a feasible alternative in these patients. Therefore, the purpose of this study was to evaluate the feasibility of clinical spectral CTA with a Gd-based contrast agent in patients with aortic aneurysms. Methods Twenty-one consecutive scans in 15 patients with and without endovascular aneurysm repair showing contraindications for iodine-based contrast agents were examined using clinical routine doses (0.2 mmol/kg) of Gd-based contrast agent with spectral CT. Monoenergetic reconstructions of the spectral data set were computed. Results There was a significant increase in the intravascular attenuation of the aorta between pre- and post-contrast images for the MonoE40 images in the thoracic and the abdominal aorta (p < 0.001 for both). Additionally, the ratio between pre- and post-contrast images was significantly higher in the MonoE40 images as compared to the conventional images with a factor of 6.5 ± 4.5 vs. 2.4 ± 0.5 in the thoracic aorta (p = 0.003) and 4.1 ± 1.8 vs. 1.9 ± 0.5 in the abdominal aorta (p < 0.001). Conclusions To conclude, our study showed that Gd-CTA is a valid and reliable alternative for diagnostic imaging of the aorta for clinical applications. Monoenergetic reconstructions of computed tomography angiographies using gadolinium based contrast agents may be a useful alternative in patients with aortic aneurysms and contraindications for iodine based contrast agents.

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“…This previous study used a newer generation reconstruction technique; therefore, use of newer technique has the potential to improve arterial depiction and image quality. Although evaluation of parenchymal abdominal organs was not the intent of this study, we believe that in theory enhancement of the abdominal organs will maintain on VMIs at 40 keV with 300 mg of iodine per kilogram, and this protocol is useful in a clinical setting because VMIs at 65 keV with 400 mg of iodine per kilogram demonstrated sufficient enhancement of the abdominal organs (22).…”

Section: Discussionmentioning

confidence: 99%

Optimized Bolus Threshold for Dual-Energy CT Angiography with Monoenergetic Images: A Randomized Clinical Trial

et al. 2021

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C T angiography (CTA) has been widely used for a broad range of indications: evaluation of aortic vascular anatomy and disease condition (1), therapy planning for endovascular aortic aneurysm repair and transcatheter aortic valve implantation (2,3), and follow-up after endovascular aortic aneurysm repair (4). Surveillance imaging with CTA after endovascular aortic aneurysm repair is routinely recommended in detecting potential complications such as endoleak (5). Patients undergoing endovascular aortic aneurysm repair often have associated medical comorbidities including varying degrees of renal dysfunction. Intravenous iodinated contrast agent administration for CTA often poses the risk for contrast agent-associated acute renal injury, which is related to the iodine load (6,7).Virtual monochromatic images (VMIs) generated from a dual-energy CT (DECT) acquisition have been reported to enable lower iodine load in several studies (8-10). VMIs at lower energy levels show increased CT numbers because of approximation of the energy level closer to the k-edge of iodine at 33 keV (11). DECT angiography (DECTA) with reduced iodine dose (24 g) provided up to 185% higher CT attenuation and 25% higher contrast-to-noise ratio at low-energy VMIs compared with conventional single-energy CTA (SECTA) at 120 kVp by using a standard iodine dose (33.3 g) ( 9). Studies investigating DECTA commonly use a threshold of 100 HU for triggering scanning with the bolus-tracking technique (9,12-14), a threshold adapted from traditional single-energy CT Background: The bolus-tracking technique from single-energy CT has been applied to dual-energy CT (DECT) without optimization or validation. Further optimization is imperative because of a paucity of literature and differences in the attenuation profile of virtual monoenergetic images (VMIs).Purpose: To determine the optimal trigger threshold with bolus-tracking technique for DECT angiography (DECTA) in a phantom study and assess the feasibility of an optimized threshold for bolus-tracking technique in DECTA at 40 keV with a 50% reduced iodine dose in human participants. Materials and Methods:A phantom study with rapid kilovoltage-switching DECT was performed to determine the optimal threshold for each kiloelectron-volt VMI. In a prospective study, consecutive participants who underwent whole-body CT angiography (CTA) from August 2018 to July 2019 were randomized into three groups: single-energy CTA (SECTA) with standard iodine dose (600 mg of iodine per kilogram), DECTA with 50% reduced iodine dose (300 mg of iodine per kilogram) by using a conventional threshold, and DECTA with 300 mg of iodine per kilogram by using an optimized threshold. A trigger threshold of 100 HU at 120 kVp was used as a reference for comparison. Injected iodine doses and aortic CT numbers were compared among the three groups using Kruskal-Wallis test.Results: Ninety-six participants (mean age 6 standard deviation, 72 years 6 9; 80 men) were evaluated (32 participants in each group). The optimized threshold for VMIs at ...

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Iodine dose optimization in portal venous phase virtual monochromatic images of the abdomen: Prospective study on rapid kVp switching dual energy CT

Cited by 16 publications

References 15 publications

Comparison of radiation dose and image quality between fast kVp switching dual-energy CT and routine single-energy CT for whole abdomen at King Chulalongkorn Memorial Hospital

Comparison of radiation dose and image quality between fast kVp switching dual-energy CT and routine single-energy CT for whole abdomen at King Chulalongkorn Memorial Hospital

Spectral computed tomography angiography using a gadolinium-based contrast agent for imaging of pathologies of the aorta

Optimized Bolus Threshold for Dual-Energy CT Angiography with Monoenergetic Images: A Randomized Clinical Trial

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