Low-dose Contrast Research Articles

Application value of individualized tube voltage, contrast injection, and adaptive statistical iterative reconstruction V algorithm based on body mass index in renal computed tomography angiography for radiation and iodinated contrast dose reduction.

To explore the application value of body mass index (BMI)-based kilovoltage peak (kVp) selection and contrast injection protocol combined with different adaptive statistical iterative reconstruction V (ASIR-V) strengths in renal computed tomography angiography (CTA) in reducing radiation and contrast medium (CM) doses. One-hundred renal CTA patients were prospectively enrolled and were divided into individualized kVp group (group A, n = 50) and conventional 100kVp group (group B, n = 50), both with automatic tube current modulation and CM of Iohexol at 350mgI/mL concentration. Group A: 70kVp, noise index (NI) of 18 and CM dose rate of 17mgI/kg/s for 10 s for BMI <25kg/m2 patients; 80kVp, NI = 17, and CM dose rate of 19mgI/kg/s for 10 s for 25 kg/m2≤BMI≤30kg/m2 patients. Group B: 100kVp, 50 mL of CM at the flow rate of 4.5 mL/s. The objective image quality, effective radiation dose, CM dose, injection rate, and image quality were compared between the 2 groups. There was no significant difference in patient characteristics between the 2 groups (P > .05). Compared to group B, group A significantly reduced effective radiation dose by 28.4%, CM dose by 27.2%, and injection rate by 22.7% (all P < .001). The 2 groups had similar SD values in erector spine (P > .05). Group A had significantly higher CT values, SNR, and CNR values of the renal arteries than group B (all P < .001). The 2 radiologists had excellent agreement (Kappa value > 0.8) in the subjective scores of renal CTA images and showed no statistically significant difference between the 2 groups (4.57 ± 0.42 vs 4.41 ± 0.49) (P > .05). BMI-based scan and reconstruction protocol in renal CTA significantly reduces radiation and contrast doses while maintaining diagnostic image quality. (i) BMI-based individualized tube voltage selection and contrast injection protocol in renal CTA reduces both radiation and contrast doses over conventional protocol. (ii) The combination of lower kVp and higher weight ASIR-V maybe used to improve image quality in terms of contrast enhancement and image noise under lower radiation and contrast dose conditions. (iii) Renal CTA of normal size (BMI ≤ 30kg/m2) patients acquired at low radiation dosage and low iodine contrast dose through the combination of low tube voltage and ASIR-V algorithm achieves excellent diagnostic image quality with a good inter-rater agreement.

Investigation in image quality and immediate patient safety using pre-dual-flow injection for low-contrast dose spectral pulmonary artery CT angiography

PurposeThe patient safety of iodine contrast-enhanced pulmonary artery CT angiography (CTPA) is widely concerned. This study aimed to investigate the image quality and immediate patient safety of spectral CTPA using a lower-contrast dose pre-dual-flow injection method. MethodsThis retrospective study included 120 patients with suspected pulmonary embolisms who received spectral CTPA between February and December 2022. Patients were divided into normal contrast injection (Group A, n=60) and pre-dual-flow group (Group B, n=60). CT values of pulmonary arteries (PAs) at different levels, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), arteriovenous separation performance, and beam hardening artifact (BHA) index of two sets of images were measured or calculated. The subjective image quality and immediate patient safety were also scored using the three-point method. ResultsGroup B had a contrast dose reduction by 42.5 % (60 vs. 34.5 mL). Radiation exposure dose was not statistically different between the two groups (P>0.05). CT values of different-level PAs on group B images were higher than those on group A images (P<0.05). Group B images had higher SNR and CNR, better arteriovenous separation between PA trunk and pulmonary vein, and lower BHA index on soft tissue and PA (all P<0.05). For subjective evaluation of image quality, group B had a better score in beam hardening artifact (P<0.05). For immediate patient safety, the score in comfortability was statistically higher in group B, with P<0.05. ConclusionsComparing with the normal injection method, pre-dual-flow spectral CTPA with a lower contrast dose injected results in better image quality and shows potential in patient-safety promotion.

Evaluation of image quality on low contrast media with deep learning image reconstruction algorithm in prospective ECG-triggering coronary CT angiography.

To assess the impact of low-dose contrast media (CM) injection protocol with deep learning image reconstruction (DLIR) algorithm on image quality in coronary CT angiography (CCTA). In this prospective study, patients underwent CCTA were prospectively and randomly assigned to three groups with different contrast volume protocols (at 320mgI/mL concentration and constant flow rate of 5ml/s). After pairing basic information, 210 patients were enrolled in this study: Group A, 0.7mL/kg (n = 70); Group B, 0.6mL/kg (n = 70); Group C, 0.5mL/kg (n = 70). All patients were examined via a prospective ECG-triggered scan protocol within one heartbeat. A high level DLIR (DLIR-H) algorithm was used for image reconstruction with a thickness and interval of 0.625mm. The CT values of ascending aorta (AA), descending aorta (DA), three main coronary arteries, pulmonary artery (PA), and superior vena cava (SVC) were measured and analyzed for objective assessment. Two radiologists assessed the image quality and diagnostic confidence using a 5-point Likert scale. The CM doses were 46.81 ± 6.41mL, 41.96 ± 7.51mL and 34.65 ± 5.38mL for Group A, B and C, respectively. The objective assessments on AA, DA and the three main coronary arteries and the overall subjective scoring showed no significant difference among the three groups (all p > 0.05). The subjective assessment proved that excellent CCTA images can be obtained from the three different contrast media protocols. There were no significant differences in intracoronary attenuation values between the higher HR subgroup and the lower HR subgroup among three groups. CCTA reconstructed with DLIR could be realized with adequate enhancement in coronary arteries, excellent image quality and diagnostic confidence at low contrast dose of a 0.5mL/kg. The use of lower tube voltages may further reduce the contrast dose requirement.

Study of Low kV, Low Contrast Agent Dosage, and Low Contrast Agent Flow Rate Scan in Computed Tomography Angiography of Children's Liver

Background: During computed tomography (CT) examinations, the presence of radiation material undoubtedly has a certain impact on patients, particularly children, who are more susceptible to radiation. Consequently, finding ways to minimize radiation dosage and mitigate radiation-related risks while enhancing the quality and accuracy of CT scans has become a crucial concern for medical professionals in CT equipment manufacturing companies and radiology departments to contemplate. Objectives: This study aimed to explore the feasibility of low dose and low contrast medium combined with low flow rate scanning in CT angiography (CTA) of children's liver. Patients and Methods: A total of 59 children who visited our department for liver vascular CT scans between April 2021 and December 2022 were prospectively selected and randomly divided into 2 groups: the experimental group and the control group. The experimental group consisted of 28 children who received an injection of 80 kV, automatic tube current, low contrast dose (1.5 mL/kg), and low flow rate of 20 s. The control group included 31 children who were injected with 100 kV, automatic tube current, contrast agent dose (2 mL/kg), and flow rate of 16 s. The objective and subjective image quality, radiation dose, and iodine intake in the arterial, portal, and venous phases were compared between the 2 groups. Results: During the arterial, portal, and venous phases, the experimental group exhibited lower signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) compared to the control group (P &lt; 0.05). However, there was no significant difference in subjective quality scores between the 2 groups (P &gt; 0.05). The effective dose (ED), volume CT dose index (CTDIvol), and dose-length product (DLP) of the experimental group were lower than those of the control group (P &lt; 0.05). Additionally, the iodine intake in the experimental group was lower than that in the control group (P &lt; 0.05). Conclusion: In the examination of hepatic vascular CTA in children, the use of a 3-low scanning technique can effectively decrease radiation and contrast agents while ensuring sufficient image quality for accurate clinical diagnosis.

Magnetic Resonance Angiography with Hour-Scale Duration after Single Low-Dose Administration of Biocompatible Gadolinium Oxide Nanoprobe.

Long-term contrast-enhanced angiography offers significant advantages in theranostics for diverse vascular diseases, particularly in terms of real-time dynamic monitoring during acute vascular events; However, achieving vascular imaging with a duration of hours through a single administration of low-dose contrast agent remains challenging. Herein, a hyaluronic acid-templated gadolinium oxide (HA@Gd2O3) nanoprobe-enhanced magnetic resonance angiography (MRA) is proposed to address this bottleneck issue for the first time. The HA@Gd2O3 nanoprobe synthesized from a facile one-pot biomineralization method owns ultrasmall size, good biocompatibility, optimal circulation half-life (≈149 min), and a relatively high T1 relaxivity (r1) under both clinical 3 T (8.215 mM-1s-1) and preclinical 9.4 T (4.023 mM-1s-1) equipment. The HA@Gd2O3 nanoprobe-enhanced MRA highlights major vessels readily with significantly improved contrast, extended imaging duration for at least 2 h, and ultrahigh resolution of 0.15mm under 9.4 T, while only requiring half clinical dosage of Gd. This technique can enable rapid diagnosis and real-time dynamic monitoring of vascular changes in a model of acute superior mesenteric vein thrombosis with only a single injection of nanoprobe. The HA@Gd2O3 nanoprobe-enhanced MRA provides a sophisticated approach for long-term (hour scale) vascular imaging with ultrahigh resolution and high contrast through single administration of low-dose contrast agent.

Spatiotemporal frequency domain analysis for blood velocity measurement during embolization procedures.

Currently, determining procedural endpoints and treatment efficacy of vascular interventions is largely qualitative and relies on subjective visual assessment of digital subtraction angiography (DSA) images leading to large interobserver variabilities and poor reproducibility. Quantitative metrics such as the residual blood velocity in embolized vessel branches could help establish objective and reproducible endpoints. Recently, velocity quantification techniques based on a contrast enhanced X-ray sequence such as qDSA and 4D DSA have been proposed. These techniques must be robust, and, to avoid radiation dose concerns, they should be compatible with low dose per frame imageacquisition. To develop and evaluate a technique for robust blood velocity quantification from low dose contrast enhanced X-ray image sequences that leverages the oscillating signal created by pulsatile bloodflow. The proposed spatiotemporal frequency domain (STF) approach quantifies velocities from time attenuation maps (TAMs) representing the oscillating signal over time for all points along a vessel centerline. Due to the time it takes a contrast bolus to travel along the vessel centerline, the resulting TAM resembles a sheared sine wave. The shear angle is related to the velocity and can be determined in the spatiotemporal frequency domain after applying the 2D Fourier transform to the TAM. The approach was evaluated in a straight tube phantom using three different radiation dose levels and compared to ultrasound transit-time-based measurements. The STF velocity results were also compared to previously published approaches for the measurement of blood velocity from contrast enhanced X-ray sequences including shifted least squared (SLS) and phase shift (PHS). Additionally, an in vivo porcine study (n = 8) was performed where increasing amounts of embolic particles were injected into a hepatic or splenic artery with intermittent velocity measurements after each injection to monitor the resulting reduction invelocity. At the lowest evaluated dose level (average air kerma rate 1.3 mGy/s at the interventional reference point), the Pearson correlation between ultrasound and STF velocity measurements was . This was significantly higher ( ) than corresponding correlation results between ultrasound and the previously published SLS and PHS approaches ( and , respectively). In the in vivo study, a reduction in velocity was observed in of cases after injection of 1 mL, after 3 mL, and after 4 mL of embolicparticles. The results show good agreement of the spatiotemporal frequency domain approach with ultrasound even in low dose per frame image sequences. Additionally, the in vivo study demonstrates the ability to monitor the physiological changes due to embolization. This could provide quantitative metrics during vascular procedures to establish objective and reproducibleendpoints.

Intraprocedural, Intra-Arterial CT Foot Perfusion Examination for Assessment of Endovascular Therapy in Patients With Critical Limb Ischemia: A Prospective Pilot Study.

Current techniques to evaluate computed tomography (CT) foot perfusion in patients with critical limb ischemia use high contrast doses and cannot be used during endovascular procedures. CT perfusion of the foot with intra-arterial contrast injection during endovascular treatment in a hybrid angiography CT suite might solve these problems. The main objective of this study was to evaluate whether intra-arterial CT foot perfusion using a hybrid CT angiosystem is feasible during endovascular treatment for critical limb ischemia. This prospective pilot study investigated intraprocedural, intra-arterial CT perfusion of the foot using a hybrid CT angiosystem in 12 patients before and after endovascular treatment for critical limb ischemia. Time to peak (TTP) and arterial blood flow were measured before and after treatment and compared using a paired t test. All 24 CT perfusion maps could be calculated adequately. The contrast volume used for one perfusion CT scan was 4.8 ml. The mean TTP before treatment was 12.8 seconds (standard deviation [SD] 2.8) and the mean TTP posttreatment was 8.4 seconds (SD 1.7), this difference being statistically significant (p=.001). Tendency toward increased blood flow after treatment, 340 ml/min/100 ml (SD 174) vs 514 ml/min/100 ml (SD 366) was noticed (p=.104). The mean effective radiation dose was 0.145 mSv per scan. Computed tomography perfusion of the foot with low contrast dose intra-arterial contrast injection during endovascular treatment in a hybrid angiography CT suite is a feasible technique. Intra-arterial CT foot perfusion using a hybrid CT-angiography system is a feasible new technique during endovascular therapy for critical limb ischemia to assess the results of the treament. Future research is necessary in defining endpoints of endovascular treatment and establishing its role in limb salvage prognostication.

Low dose of contrast agent and low radiation liver computed tomography with deep-learning-based contrast boosting model in participants at high-risk for hepatocellular carcinoma: prospective, randomized, double-blind study.

To investigate the image quality and lesion conspicuity of a deep-learning-based contrast-boosting (DL-CB) algorithm on double-low-dose (DLD) CT of simultaneous reduction of radiation and contrast doses in participants at high-risk for hepatocellular carcinoma (HCC). Participants were recruited and underwent four-phase dynamic CT (NCT04722120). They were randomly assigned to either standard-dose (SD) or DLD protocol. All CT images were initially reconstructed using iterative reconstruction, and the images of the DLD protocol were further processed using the DL-CB algorithm (DLD-DL). The primary endpoint was the contrast-to-noise ratio (CNR), the secondary endpoint was qualitative image quality (noise, hepatic lesion, and vessel conspicuity), and the tertiary endpoint was lesion detection rate. The t-test or repeated measures analysis of variance was used for analysis. Sixty-eight participants with 57 focal liver lesions were enrolled (20 with HCC and 37 with benign findings). The DLD protocol had a 19.8% lower radiation dose (DLP, 855.1 ± 254.8mGy·cm vs. 713.3 ± 94.6mGy·cm, p = .003) and 27% lower contrast dose (106.9 ± 15.0mL vs. 77.9 ± 9.4mL, p < .001) than the SD protocol. The comparative analysis demonstrated that CNR (p < .001) and portal vein conspicuity (p = .002) were significantly higher in the DLD-DL than in the SD protocol. There was no significant difference in lesion detection rate for all lesions (82.7% vs. 73.3%, p = .140) and HCCs (75.7% vs. 70.4%, p = .644) between the SD protocol and DLD-DL. DL-CB on double-low-dose CT provided improved CNR of the aorta and portal vein without significant impairment of the detection rate of HCC compared to the standard-dose acquisition, even in participants at high risk for HCC. • Deep-learning-based contrast-boosting algorithm on double-low-dose CT provided an improved contrast-to-noise ratio compared to standard-dose CT. • The detection rate of focal liver lesions was not significantly differed between standard-dose CT and a deep-learning-based contrast-boosting algorithm on double-low-dose CT. • Double-low-dose CT without a deep-learning algorithm presented lower CNR and worse image quality.

FACTORS FAVORING PREFERENCE OF ARTERIOGRAPHY OVER CT ANGIOGRAPHY FOR PERIPHERAL ARTERIAL DISEASE EVALUATION

Despite many advances in the quality and availability of less invasive arterial imaging modalities, arteriography remains the “gold standard.” This is a Prospective study which analyzes the factors favoring the preference of DSA over CTA in patients with peripheral vascular disease. Those patients with peripheral vascular disease undergoing DSA, who were initially planned for CTA and could not undergo CTA for various reasons were included. This study consists of 38 patients with most of them were males 29 (76%). In our study common factor for referral over CTA was renal dysfunction patients 18 out of 38 ( 47%), as contrast required in standard CTA for lower limb runoff is around 100ml and in our DSA average volume required is only 30ml because of target lesion arteriography with magnication. Next common factor was presence of heavy calcications in tibial vessel walls which hampers the evaluation of the CTA who were 37% of our study patients (14). Other factors were severe congestive Cardiac Failure, Previous Bone Plating/Nailing in leg bones and limb Contracture. With increasing incidences of diabetic patients with their associated diabetic nephropathy and heavy calcicated arteries, makes these patients more preferred for DSA than CTA due to its low contrast dose requirements and images free of calcication artefacts

High-Pitch Multienergy Coronary CT Angiography in Dual-Source Photon-Counting Detector CT Scanner at Low Iodinated Contrast Dose.

The aim of this study was to evaluate the high-helical pitch, multienergy (ME) scanning mode of a clinical dual-source photon-counting detector (PCD) computed tomography (CT) and the benefit of virtual monoenergetic images (VMIs) for low-contrast-dose coronary CT angiography (CTA). High-pitch (3.2) ME coronary CTA was performed in PCD-CT in 27 patients using low contrast dose (30 mL of iohexol 350 mg/mL) and in 26 patients at routine contrast dose (60 mL). Low-energy-threshold 120 kV images (also known as T3D images) and 50 kiloelectron volts (50 keV) and 100 kiloelectron volts (100 keV) VMIs were reconstructed using a 1024 × 1024 matrix and 0.6-mm slices. The CT numbers, noise, and contrast-to-noise ratio (CNR) were measured in the ascending aorta (AA), left main coronary artery (LMCA), and distal left anterior descending (LAD) artery. Confidence in grading luminal stenosis with calcific plaque, noncalcific plaque, and stent was evaluated by 2 independent readers on a 0-100 scale (0 the lowest), and a CAD-RADS score was assigned. Image contrast enhancement, sharpness, noise, artifacts, and overall image quality were rated using a 5-point ordinal scale (1 the lowest). The radiation doses (CTDI) in low- and routine-contrast cohorts were 2.5 ± 0.6 mGy and 3.1 ± 1.7 mGy, respectively ( P = 0.12). At all measured locations, the mean CT number was >300 HU in 120 kV (LMCA 382.9 ± 76.2, distal LAD 341.0 ± 53.9, AA 399.5 ± 76.1) and 50 keV images (LMCA 667.5 ± 139.9, distal LAD 578.1 ± 121.5, AA 700.8 ± 142.5) in the low-contrast cohort, with a 96% increase in CT numbers for 50 keV over 120 kV. The CT numbers were significantly higher ( P < 0.0001) in 50 keV than 120 kV and 100 keV VMI. The CNR was also significantly ( P < 0.0001) higher in 50 keV than 120 kV and 100 keV images in all vessels. Confidence in the assessment of luminal stenosis in the presence of calcific plaque was significantly higher ( P = 0.001) with the addition of 100 keV VMI (median score, 100) than using 50 keV alone (median score, 70) and 120 kV (median score, 70) for reader 1, but no significant differences were seen for reader 2 who had same median scores of 100 for all image types. The confidence in the assessment of luminal stenosis within a stent improved with the use of 100 keV images for both readers (reader 1: median scores for 50 + 100 keV = 100, 50 keV = 82.5, 120 kV = 82.5; reader 2: 50 + 100 keV = 100, 50 keV = 90, 120 kV = 90). There were no significant differences in confidence scores for assessment of luminal stenosis from noncalcific plaques for both readers. The reader-averaged qualitative scores for vascular enhancement and overall image quality were significantly higher for 50 keV VMI than for 120 kV images in both low- and routine-contrast dose cohorts. The image sharpness was nonsignificantly higher at 50 keV VMI than 120 kV images, and the artifact score was comparable for 50 keV VMI and 120 kV images. The noise was higher in 50 keV VMI than in 120 kV images. High-pitch ME PCD-CT mode produced diagnostic quality coronary CTA images at low radiation and iodinated contrast doses. The availability of ME VMIs significantly improved the CNR, overall image quality, and confidence in assessment of luminal stenosis in the presence of calcific plaques and stents, and resulted in change of CAD-RADS categories in 9 patients.

Evaluation of non-breath-hold, ultra-fast, low-dose high-pitch (flash) CT scan as a practical alternative to standard spiral scan for pre-TAVI patients: a real-world single-center experience

Abstract Introduction and aim Aortic annulus dimensions change during the cardiac cycle. A retrospective ECG-gated (Spiral) scan is the default technique for pre TAVR evaluation since it includes systolic phases considered optimal for aortic annulus assessment. Ultra-fast, Low-Dose High-Pitch (FLASH) offers faster, potentially low radiation and low contrast dose scans. However, it lacks the ability to time data acquisition to the systole. Therefore, measurements derived from FLASH scan are considered suboptimal for reporting. The effect of this potential annular measurement difference on procedural success and safety was not evaluated. Therefore, we aimed to assess the feasibility and safety of FLASH vs. Spiral scan before TAVI. Methods We conducted a retrospective, single-center study. 409 patients underwent CT-TAVI scan with either FLASH or SPIRAL acquisition. Baseline characteristics, CT study, procedural and f/u data were acquired from the EMR. Outcomes defined by Valve Academic Research Consortium3 (VARC-2) endpoint definitions included in-hospital mortality, bleeding, vascular complications, acute kidney injury (AKI), conduction disorders, mechanical complications, and prosthetic aortic valve regurgitation. Composite endpoints such as device success were also examined. Results Of the 409 patients, 55.7% underwent FLASH scans. The median age was 80 years, and males accounted for 55%. The FLASH-protocol patients had higher rate of chronic kidney disease, their CT-measured aortic annulus area and diameter were smaller, and they were exposed to a smaller amount of contrast agent and radiation than the SPIRAL group. There was no statistically significant difference in primary clinical and safety endpoints between the two groups, including mechanical complications (such as annular rupture and valve malposition) and conduction disorders. Conclusions FLASH CT scan is a pragmatic and safe approach that potentially may replace spiral scan for the evaluation before TAVI procedure in the appropriate patients. Funding Acknowledgement Type of funding sources: None.

Bone segmentation in contrast enhanced whole-body computed tomography

Segmentation of bone regions allows for enhanced diagnostics, disease characterisation and treatment monitoring in CT imaging. In contrast enhanced whole-body scans accurate automatic segmentation is particularly difficult as low dose whole body protocols reduce image quality and make contrast enhanced regions more difficult to separate when relying on differences in pixel intensities. This paper outlines a U-net architecture with novel preprocessing techniques, based on the windowing of training data and the modification of sigmoid activation threshold selection to successfully segment bone-bone marrow regions from low dose contrast enhanced whole-body CT scans. The proposed method achieved mean Dice coefficients of 0.979 ± 0.02, 0.965 ± 0.03, and 0.934 ± 0.06 on two internal datasets and one external test dataset respectively. We have demonstrated that appropriate preprocessing is important for differentiating between bone and contrast dye, and that excellent results can be achieved with limited data.

Artificial intelligence-based full aortic CT angiography imaging with ultra-low-dose contrast medium: a preliminary study.

To further reduce the contrast medium (CM) dose of full aortic CT angiography (ACTA) imaging using the augmented cycle-consistent adversarial framework (Au-CycleGAN) algorithm. We prospectively enrolled 150 consecutive patients with suspected aortic disease. All received ACTA scans of ultra-low-dose CM (ULDCM) protocol and low-dose CM (LDCM) protocol. These data were randomly assigned to the training datasets (n = 100) and the validation datasets (n = 50). The ULDCM images were reconstructed by the Au-CycleGAN algorithm. Then, the AI-based ULDCM images were compared with LDCM images in terms of image quality and diagnostic accuracy. The mean image quality score of each location in the AI-based ULDCM group was higher than that in the ULDCM group but a little lower than that in the LDCM group (all p < 0.05). All AI-based ULDCM images met the diagnostic requirements (score ≥ 3). Except for the image noise, the AI-based ULDCM images had higher attenuation value than the ULDCM and LDCM images as well as higher SNR and CNR in all locations of the aorta analyzed (all p < 0.05). Similar results were also seen in obese patients (BMI > 25, all p < 0.05). Using the findings of LDCM images as the reference, the AI-based ULDCM images showed good diagnostic parameters and no significant differences in any of the analyzed aortic disease diagnoses (all K-values > 0.80, p < 0.05). The required dose of CM for full ACTA imaging can be reduced to one-third of the CM dose of the LDCM protocol while maintaining image quality and diagnostic accuracy using the Au-CycleGAN algorithm. • The required dose of contrast medium (CM) for full ACTA imaging can be reduced to one-third of the CM dose of the low-dose contrast medium (LDCM) protocol using the Au-CycleGAN algorithm. • Except for the image noise, the AI-based ultra-low-dose contrast medium (ULDCM) images had better quantitative image quality parameters than the ULDCM and LDCM images. • No significant diagnostic differences were noted between the AI-based ULDCM and LDCM images regarding all the analyzed aortic disease diagnoses.

Effect of Low-Dose Contrast Agent Combined with Saline for Second-Generation Two-Source Head and Neck Vascularization Of CT

Effect of Low-Dose Contrast Agent Combined with Saline for Second-Generation Two-Source Head and Neck Vascularization Of CT

Reducing amount of contrast agent after compression of right brachial artery using a blood pressure cuff in computed tomography cerebrovascular angiography.

To invastgate feasibility of low-dose contrast agent in cerebral computed tomography angiography (CTA) to alleviate side effects. Siemens' Somatom Definition AS+CT scanner, Heine's blood pressure monitor G7-M237 (BP cuff) and Ultravist contrast agent (370 mg Iodine/ml) are used. CTA is acquired using following scan parameters including slice thickness of 1mm, image acquisition parameters of 128×0.6 mm, pitch size of 0.8 mm, 175 effective mAs, 120 kVp tube voltage, scan delay time of 3 seconds, and the scan time of 4 seconds. This study is conducted by securing the IV route in the left antecubital vein before injection of contrast agent, wrapping BP cuff around the branchial artery of the opposite right arm after setting the pressure to 200 mmHg. Then, the injection rate of the contrast agent is fixed at 4.5 cc/sec and contrast agent was injected in three different amounts (70, 80, and 100 cc). Bp cuff is released from this moment when HU value reachs 100. In this study, the mean HU values measured from common carotid artery are 412.45±5.89 when injecting 80cc contrast agent and using BP cuff and 399.64±5.51 when injecting 100 cc contrast agenet and not using BP cuff, respectively. In middle cerebral artery M1, the mean HU values are 325.23±38.29 when injecting 80cc contrast agent and using BP cuff and 325.00±30.63 when injecting 100cc contrast agent blood and not using pressure cuff, respectively. Difference of mean HU values is not statistically significant (p > 0.05) with and without using BP cuff. This study demonstrates that reducing amount of contrast agent is possible when the right brachial artery is compressed using BP cuff. Study results indicate that reducing 20% injection of contrast agent in CT cerebrovascular angiography can still yield comparable imaging results with conventional contrast angent usage, which implies that less side effects are expected with a contrast agent injection. Thus, this study can serve as a reference for potential reducing side effect during CT cerebrovascular angiography.

Comparison of low-dose contrast computed tomography angiography findings with surgical results in living kidney donors

Aim: To analyze the image quality and diagnostic performance of CT angiography using low dose (60 ml) contrast medium for living kidney donors and compare with surgical results.&#x0D; Material and Method: Angiographic findings of 81 renal donor candidates in 128-slice MDCT were evaluated by two independent radiologists in terms of renal artery number, early bifurcation, renal vein variations, pelvicalyceal system and ureter variations. Results were compared with intraoperative findings. The image quality, diagnostic performance and interobserver agreement of MDCT obtained with low dose contrast material were analyzed.&#x0D; Results: The mean age of the 81 living kidney donors included in the study was 49±12 (24-68) years. Left nephrectomy was performed in 71% (n=64) and right nephrectomy in 29% (n=17) of the donors. Intraoperative accessory arteries were detected in 22.2% (n:18) of the donors. The specificity, sensitivity, and accuracy for detecting accessory artery variation in MDCT were 100%, 88.9%, and 97.5%, respectively. Early bifurcation was observed in 21% (n=17) of the donors. Specificity, sensitivity and accuracy for early bifurcation detection were 98.4%, 94.1% and 97.5%, respectively. Renal vein variation was detected in 12.3% (n=10) of the donors. Specificity, sensitivity, and accuracy for renal vein variation detection were 100%. Variations of the pelvicalyceal system and ureter were observed in 3.7% (n=3) of the donors. The specificity, sensitivity, and accuracy for detecting pelvicalyceal system and ureteral variations were 100%. Interobserver agreement was excellent in detecting variations of accessory arteries, renal venous anomalies, pelvicalyceal system and ureters by MDCT (kappa: 1,000; p&lt; 0.001). It was higher in early bifurcation detection (kappa: 0.853; p&lt; 0.001).&#x0D; Conclusion: MDCT angiography with a lower dose of iodine contrast at 60 mL in kidney donors is sufficient to detect vascular anomalies and provide anatomical information. It is possible to reduce the contrast agent dose in CTA without affecting the preoperative evaluation.

Low kilovoltage and low contrast volume neck CT protocol using iterative reconstruction techniques: A comparison with standard dose protocol

Computed Tomography (CT) is standard imaging modality for evaluation of neck pathologies. The increased radiation risks and effects of contrast media has drawn attention for using low dose and low contrast volume protocols in the recent years. The aim of the study is to evaluate the image quality and radiation dose of 80 kVp (iDose4) with low contrast volume Neck CT compared to 120 kVp standard Neck CT. This is prospective study with historical controls. In Group A, twenty-five patients who had undergone Contrast Enhanced Neck CT from August 2019–August 2020 using standard dose protocol (120 kVp, 60 ml Contrast) were included. In Group B twenty-five patients who was referred for Contrast Enhanced Neck CT from September 2020–March 2021 using low dose protocol (80 kVp, 40 ml contrast) were included. The qualitative analysis of standard (120 kVp) and low dose (80 kVp, iDose4) images did not show significant difference between two groups (p > 0.05). Contrast to Noise Ratio (CNR) showed significant difference between two groups and was slightly higher in 80 kVp (iDose4) images. There was 69.2% reduction in effective dose with 80 kVp (iDose4) protocol. The qualitative analysis of low dose protocol with Filtered back projection (FBP) and iDose4 of group B showed significant difference between both (p < 0.001). The Image noise (IN) was more, Signal to Noise Ratio (SNR) and CNR was less in FBP compared to iDose4 of Group B. The study concludes that low kilovoltage (80 kVp) and low contrast volume Neck CT protocol used with iterative reconstruction technique (iDose4) provides optimum diagnostic image quality with reduced radiation dose compared with standard dose protocol (120 kVp).

701 ECMO assistance during TAVI in high-risk patient with recent COVID-19 pneumonia

Methods and resultsA 87 years old woman, with history of dyslipidemia and permanent Atrial Fibrillation, already undergone full SARS-CoV2 vaccination few months before, referred to our E.R. with complain of dyspnoea and chest pain. COVID-19 molecular test resulted positive and CT Scan of the chest confirmed the presence of several areas of ground-glass opacity and consolidation together with bilateral pleural effusion (right 6 cm with pulmonary atelectasis; left 2 cm), not requiring drainage. Moreover, it showed severe calcification of both the aortic valve and root. Transthoracic echocardiogram showed eccentric LV hypertrophy with diffuse hypokinesia (EF 20–25%), ectatic ascending aorta (45 mm) with severe LF-LG aortic stenosis (AVAi 0.19 cm2) and moderate regurgitation, moderate-severe mitral regurgitation. During hospitalization in the COVID-19 Unit, despite O2 therapy she experienced worsening of the respiratory status with concomitant pulmonary oedema, hypotension and acute kidney injury, requiring administration of i.v. dobutamine and high dose diuretics. After gradual stabilization and COVID-19 negativization on 10th molecular test, she was transferred to our Coronary Care Unit. Coronary angiography showed absence of significant stenoses in the main vessels. In the following days the patient underwent a new clinical deterioration with dyspnoea, hypotension (BP 85/50 mmHg), oliguria and ankle swelling, requiring Ventimask O2 therapy and Dobutamine infusion. Transtoracic echocardiogram confirmed EF of 25% with PASP 30 mmHg. We decided to perform a ‘Rescue’ TAVI procedure, facilitated by extra-corporeal cardiac and respiratory support. CT Angiography of the chest, performed with low-dose contrast injection under amines infusion, showed severly calcific aortic valve with large sizes of the ring (Virtual Basal Ring area 620 mm2, perimeter 91 mm), measures compatible with the largest sizes of TAVI prostheses. After Veno-Arterial Extracorporeal Membrane Oxygenation (ECMO) cannulation, we performed the implantation of a 34 mm Evolut R (Medtronic) TAVI prosthesis, post-dilated with 24 mm balloon for under-expansion due to massive calcification. During both self-expandable TAVI delivery and balloon inflation the patient underwent two phases of cardiac arrest, during which the ECMO flow provided a proper circulatory support.ConclusionsSince percutaneous valve replacement the patient’s recovery was fast with rapid ECMO removal and discontinuation of inotropic therapy. Few weeks after discharge, at first follow-up examination, the patient appeared asymptomatic, in excellent clinical conditions. 701 Figure

Patient-tailored Contrast Delivery Protocols for Computed Tomography Coronary Angiography: Lower Contrast Dose and Better Image Quality.

The first objective of this study was to evaluate the efficacy of a patient-tailored contrast delivery protocol for coronary computed tomography angiography (CTCA), in terms of diagnostic coronary attenuation and total iodine load (TIL), by adjusting the iodine delivery rate (IDR) via dilution for body weight and tube voltage (kV), as compared with a protocol with a fixed bolus of contrast in a clinical setting. The secondary objective was to assess the association between the test-bolus data and luminal attenuation in CTCA. Patients who underwent CTCA with fixed IDR contrast delivery (cohort 1) or with IDR adjusted for body weight and kV settings (70 to 120 kV) (cohort 2) were included, and compared for intravascular luminal attenuation and TIL. The association between intravascular luminal attenuation and test-bolus scan data was investigated with linear regression. In cohort 1 (176 patients), the mean luminal attenuation differed markedly between kV categories, whereas in cohort 2 (154 patients), there were no marked differences. The mean TIL reduced significantly (20.1±1.2 g in cohort 1, 17.7±3.0 g in cohort 2, P<0.001). The peak height of the test-bolus scan was independently associated with luminal attenuation in the ascending aorta, with a 0.58 HU increase per HU peak-height increase (SE=0.18, P<0.001). Clinical implementation of a patient-tailored contrast delivery protocol for CTCA, adjusted for body weight and kV, improves luminal attenuation and significantly reduces the TIL. The peak height of the test-bolus scan is associated with luminal attenuation in the ascending aorta in the CTCA scan.

Low dose contrast media in step-and-shoot coronary angiography with third-generation dual-source computed tomography: feasibility of using 30 mL of contrast media in patients with body surface area

Reducing contrast media volume in coronary computed tomography angiography minimizes the risk of adverse events but may compromise diagnostic image quality. We aimed to evaluate coronary computed tomography angiography's diagnostic image quality while using 30 mL of contrast media in patients with a body surface area <1.7 m2. This prospective study included patients who underwent coronary computed tomography angiography from May 2018 to June 2019. The patients were divided into a low-dose group, who received 30 mL of contrast media, and a routine-dose group, who received contrast media based on body weight. Patient characteristics, coronary computed tomography angiography results, and quantitative and qualitative image results were assessed and compared. In total, 103 patients with a body surface area <1.7 m2 were 53 in the low-dose group and 50 in the routine-dose group. Sex, age, body surface area, body weight, and heart rate were similar between the groups (P>0.05). A contrast media volume of 30±0 mL was used for the low-dose group, and 41.62±4.59 mL was used for the routine-dose group. The low-dose group's computed tomography values were significantly different from those of the routine-dose group (P<0.05). The radiologists demonstrated agreement regarding diagnostic image quality and accuracy (kappa =0.91 and 0.85, respectively). Using 30 mL of contrast media for coronary computed tomography angiography in patients with a body surface area <1.7 m2 provided a suitable diagnostic image quality for coronary artery disease diagnosis. Although radiation doses were similar between the groups, the decreased contrast media volume was likely beneficial for the patients.