Venous Contamination Research Articles

Deep Learning-Based High-Resolution Magnetic Resonance Angiography (MRA) Generation Model for 4D Time-Resolved Angiography with Interleaved Stochastic Trajectories (TWIST) MRA in Fast Stroke Imaging.

The purpose of this study is to improve the qualitative and quantitative image quality of the time-resolved angiography with interleaved stochastic trajectories technique (4D-TWIST-MRA) using deep neural network (DNN)-based MR image reconstruction software. A total of 520 consecutive patients underwent 4D-TWIST-MRA for ischemic stroke or intracranial vessel stenosis evaluation. Four-dimensional DNN-reconstructed MRA (4D-DNR) was generated using commercially available software (SwiftMR v.3.0.0.0, AIRS Medical, Seoul, Republic of Korea). Among those evaluated, 397 (76.3%) patients received concurrent time-of-flight MRA (TOF-MRA) to compare the signal-to-noise ratio (SNR), image quality, noise, sharpness, vascular conspicuity, and degree of venous contamination with a 5-point Likert scale. Two radiologists independently evaluated the detection rate of intracranial aneurysm in TOF-MRA, 4D-TWIST-MRA, and 4D-DNR in separate sessions. The other 123 (23.7%) patients received 4D-TWIST-MRA due to a suspicion of acute ischemic stroke. The confidence level and decision time for large vessel occlusion were evaluated in these patients. In qualitative analysis, 4D-DNR demonstrated better overall image quality, sharpness, vascular conspicuity, and noise reduction compared to 4D-TWIST-MRA. Moreover, 4D-DNR exhibited a higher SNR than 4D-TWIST-MRA. The venous contamination and aneurysm detection rates were not significantly different between the two MRA images. When compared to TOF-MRA, 4D-CE-MRA underestimated the aneurysm size (2.66 ± 0.51 vs. 1.75 ± 0.62, p = 0.029); however, 4D-DNR showed no significant difference in size compared to TOF-MRA (2.66 ± 0.51 vs. 2.10 ± 0.41, p = 0.327). In the diagnosis of large vessel occlusion, 4D-DNR showed a better confidence level and shorter decision time than 4D-TWIST-MRA. DNN reconstruction may improve the qualitative and quantitative image quality of 4D-TWIST-MRA, and also enhance diagnostic performance for intracranial aneurysm and large vessel occlusion.

Analysis on efficacy of magnetic resonance lymphangiography using INV-001 in healthy beagle dogs

We aimed to conduct a proof-of-concept study of INV-001 in visualizing lymphatic vessels and nodes without venous contamination and to determine the optimal dose condition of INV-001 for magnetic resonance lymphangiography (MRL) in healthy beagles. MRL was performed using a 3.0-Tesla (T) whole body clinical magnetic resonance imaging (MRI) scanner. A dose-finding study of INV-001 for MRL in beagles (N = 6) was carried out according to an adaptive optimal dose finding design. For the reproducibility study (N = 6), MRL was conducted at selected INV-001 doses (0.056 and 0.112 mg Fe/kg) with a 15 mM concentration. Additionally, an excretion study (N = 3) of INV-001 was conducted by analyzing T1, T2, and T2* maps of the liver and kidney 48 h post-administration. INV-001 administration at doses of 0.056 and 0.112 mg Fe/kg (concentration: 15 mM) consistently demonstrated the visualization of contrast-enhanced lymphatic vessels and nodes without venous contamination in the beagles. The contrast enhancement effect was highest at 30 min after INV-001 administration, then gradually decreasing. No toxicity-related issues were identified during the study. After 48 h, the T1, T2, and T2* values in the liver and both kidneys were found to be comparable to the pre-administration values, indicating thorough INV-001 excretion. The optimal dosing conditions of INV-001 for MRL for contrast-enhanced visualization of lymphatic vessels and nodes exclusively with no venous contamination in beagles was determined to be 0.056 mg Fe/kg with a 15 mM concentration.

Comparison of the Pharmacokinetics of Gadolinium-Based and Iron Oxide-Based Contrast Agents inside the Lymphatic Structure using Magnetic Resonance Lymphangiography.

Gadolinium (Gd)-based contrast agents are primarily used for contrast-enhanced magnetic resonance lymphangiography (MRL). However, overcoming venous contamination issues remains challenging. This study aims to assess the MRL efficacy of the newly developed iron-based contrast agent (INV-001) that is specially designed to mitigate venous contamination issues. The study further explores the optimal dosage, including both injection volume and concentration, required to achieve successful visualization of the popliteal lymph nodes and surrounding lymphatic vessels. All animals utilized in this study were male Sprague-Dawley (SD) rats weighing between 250 and 300g. The contrast agents prepared were injected intradermally in the fourth phalanx of both hind limbs using a 30-gauge syringe in SD rats. MRL was performed every 16min on a coronal 3D time-of-flight sequence with saturation bands using a 9.4-T animal machine. Contrary to Gd-DOTA, which exhibited venous contamination in most animals irrespective of injection dosages and conditions, INV-001 showed no venous contamination. For Gd-DOTA, the popliteal lymph nodes and lymphatic vessels reached peak enhancement 16min after injection from the injection site and then rapidly washed out. However, with INV-001, they reached peak enhancement between 16 and 32min after injection, with prolonged visualization of the popliteal lymph node and lymphatic vessels. INV-001 at 0.45μmol (15mM, 30 μL) and 0.75μmol (15mM, 50 μL) achieved high scores for qualitative image analysis, providing good visualization of the popliteal lymph nodes and lymphatic vessels without issues of venous contamination, interstitial space enhancement, or lymph node enlargement. In MRL, INV-001, a novel T1 contrast agent based on iron, enables prolonged enhancement of popliteal lymph nodes and lymphatic vessels without venous contamination.

Deep Learning-Based Synthetic TOF-MRA Generation Using Time-Resolved MRA in Fast Stroke Imaging.

Time-resolved MRA enables collateral evaluation in acute ischemic stroke with large-vessel occlusion; however, a low SNR and spatial resolution impede the diagnosis of vascular occlusion. We developed a CycleGAN-based deep learning model to generate high-resolution synthetic TOF-MRA images using time-resolved MRA and evaluated its image quality and clinical efficacy. This retrospective, single-center study included 397 patients who underwent both TOF- and time-resolved MRA between April 2021 and January 2022. Patients were divided into 2 groups for model development and image-quality validation. Image quality was evaluated qualitatively and quantitatively with 3 sequences. A multireader diagnostic optimality evaluation was performed by 16 radiologists. For clinical validation, we evaluated 123 patients who underwent fast stroke MR imaging to assess acute ischemic stroke. The diagnostic confidence level and decision time for large-vessel occlusion were also evaluated. Median values of overall image quality, noise, sharpness, venous contamination, and SNR for M1, M2, the basilar artery, and posterior cerebral artery are better with synthetic TOF than with time-resolved MRA. However, with respect to real TOF, synthetic TOF presents worse median values of overall image quality, sharpness, vascular conspicuity, and SNR for M3, the basilar artery, and the posterior cerebral artery. During the multireader evaluation, radiologists could not discriminate synthetic TOF images from TOF images. During clinical validation, both readers demonstrated increases in diagnostic confidence levels and decreases in decision time. A CycleGAN-based deep learning model was developed to generate synthetic TOF from time-resolved MRA. Synthetic TOF can potentially assist in the detection of large-vessel occlusion in stroke centers using time-resolved MRA.

Central venous catheter contamination rate in suspected sepsis patients: an observational clinical study

More than 160,000 central-line-associated bloodstream infections (CLABSIs) are estimated for Europe each year, leading to about 25,000 deaths. To characterize the contamination of administration sets in suspected CLABSI cases in the intensive care unit (ICU). In ICU patients (from February 2017 to February 2018) with suspected CLABSI, all sampled central venous catheters (CVCs) were examined in four segments (from CVC tip to connected tubing systems) for contamination. A risk factor analysis using binary logistic regression was performed. Fifty-two consecutively sampled CVCs with 1004 elements were analysed with 45 elements being positive for at least one micro-organism (4.48%). There was a significant association with the duration of catheterization (P= 0.038, N= 50) with a daily increase of contamination risk by 11.5% (odds ratio: 1.115). The mean number of CVC manipulations was 40 within 72h (standard deviation: 20.5), with no association with contamination risk (P= 0.381). The contamination risk of the CVC segments decreased from proximal to distal. Non-replaceable components of the CVC had a high risk (14 times higher; P= 0.01). A significant positive correlation was detected between positive tip cultures and microbial growth in the administration set (r(49)= 0.437; P= 0.001). Although only a minority of CLABSI-suspect patients had positive blood cultures, the contamination rate of CVCs and administration set was high, possibly indicating a relevant underreporting. The finding of identical species in adjacent segments underlines the role of upward or downward spread of micro-organisms within the tubes; therefore, aseptic tasks should be emphasized.

Short Peripheral Venous Catheters Contamination and the Dangers of Bloodstream Infection in Portugal: An Analytic Study.

Peripheral venous catheters (PVCs) are the most used vascular access devices in the world. However, failure rates remain considerably high, with complications such as PVC-related infections posing significant threats to patients' well-being. In Portugal, studies evaluating the contamination of these vascular medical devices and characterizing the associated microorganisms are scarce and lack insight into potential virulence factors. To address this gap, we analyzed 110 PVC tips collected in a large tertiary hospital in Portugal. Experiments followed Maki et al.'s semi-quantitative method for microbiological diagnosis. Staphylococcus spp. were subsequently studied for the antimicrobial susceptibility profile by disc diffusion method and based on the cefoxitin phenotype, were further classified into strains resistant to methicillin. Screening for the mecA gene was also done by a polymerase chain reaction and minimum inhibitory concentration (MIC)-vancomycin as determined by E-test, proteolytic and hemolytic activity on skimmed milk 1% plate and blood agar, respectively. The biofilm formation was evaluated on microplate reading through iodonitrotetrazolium chloride 95% (INT). Overall, 30% of PVCs were contaminated, and the most prevalent genus was Staphylococcus spp., 48.8%. This genus presented resistance to penicillin (91%), erythromycin (82%), ciprofloxacin (64%), and cefoxitin (59%). Thus, 59% of strains were considered resistant to methicillin; however, we detected the mecA gene in 82% of the isolates tested. Regarding the virulence factors, 36.4% presented α-hemolysis and 22.7% β-hemolysis, 63.6% presented a positive result for the production of proteases, and 63.6% presented a biofilm formation capacity. Nearly 36.4% were simultaneously resistant to methicillin and showed expression of proteases and/or hemolysins, biofilm formation, and the MIC to vancomycin were greater than 2 µg/mL. Conclusion: PVCs were mainly contaminated with Staphylococcus spp., with high pathogenicity and resistance to antibiotics. The production of virulence factors strengthens the attachment and the permanence to the catheter's lumen. Quality improvement initiatives are needed to mitigate such results and enhance the quality and safety of the care provided in this field.

Subtractionless compressed-sensing-accelerated whole-body MR angiography using two-point Dixon fat suppression with single-pass half-reduced contrast dose: feasibility study and initial experience

PurposeTo investigate the feasibility and clinical utility of a compressed-sensing-accelerated subtractionless whole-body MRA (CS-WBMRA) protocol with only contrast injection for suspected arterial diseases, by comparison to conventional dual-pass subtraction-based whole-body MRA (conventional-WBMRA) and available computed tomography angiography (CTA). Materials and methodsThis prospective study assessed 86 patients (mean age, 56 years ± 16.4 [standard deviation]; 25 women) with suspected arterial diseases from May 2021 to December 2022, who underwent CS-WBMRA (n = 48, mean age, 55.9 years ± 16.4 [standard deviation]; 25 women) and conventional-WBMRA (n = 38, mean age, 48 years ± 17.4 [standard deviation]; 20 women) on a 3.0 T MRI after random group assignment based on the chronological order of enrolment. Of all enrolled patients administered the CS-WBMRA protocol, 35% (17/48) underwent CTA as required by clinical demands. Two experienced radiologists independently scored the qualitative image quality and venous enhancement contamination. Quantitative image assessment was carried out by determining and comparing the apparent signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of four representative arterial segments. The total examination time and contrast-dose were also recorded. The independent samples t-test or the Wilcoxon rank sum test was used for statistical analysis. ResultsThe overall scores of CS-WBMRA outperformed those of conventional-WMBRA (3.40 ± 0.60 vs 3.22 ± 0.55, P < 0.001). In total, 1776 and 1406 arterial segments in the CS-WBMRA and conventional-WBMRA group were evaluated. Qualitative image scores for 7 (of 15) vessel segments in the CS-WMBRA group had statistically significantly increased values compared to those of the conventional-WBMRA groups (P < 0.05). Scores from the other 8 segments showed similar image quality (P > 0.05) between the two protocols. In the quantitative analysis, overall apparent SNRs were significantly higher in the conventional-WBMRA group than in the CS-WBMRA group (214.98 ± 136.05 vs 164.90 ± 118.05; P < 0.001), while overall apparent CNRs were not significantly different in these two groups (CS vs conventional: 107.13 ± 72.323 vs 161.24 ± 118.64; P > 0.05). In the CS-WBMRA group, 7 of 1776 (0.4%) vessel segments were contaminated severely by venous enhancement, while in the convention-WBMRA group, 317 of 1406 (23%) were rated as severe contamination. In the CS-WBMRA group, total examination and reconstruction times were only 7 min and 10 min, respectively, vs 20 min and < 30 s for the conventional WBMRA group, respectively. The contrast agent dose used in the CS-WBMRA protocol was reduced by half compared to conventional-WBMRA protocol (18.7 ± 3.5 ml vs 37.2 ± 5.4 ml, P = 0.008). ConclusionThe CS-WBMRA protocol provides excellent image quality and sufficient diagnostic accuracy for whole-body arterial disease, with relatively faster workflow and half-dose reduction of contrast agent, which has greater potential in clinical practice compared with conventional-WBMRA.

Advanced virtual monoenergetic imaging algorithm for lower extremity computed tomography angiography: effects on image quality, artifacts, and peripheral arterial disease evaluation

To investigate the image quality of lower extremity computed tomography angiography (LE-CTA) using a reconstruction algorithm for monoenergetic images (MEIs) to evaluate peripheral arterial disease (PAD) at different kiloelectron volt (keV) levels. A total of 146 consecutive patients who underwent LE-CTA on a dual-energy scanner to obtain MEIs at 40, 50, 60, 70, and 80 keV were included. The overall image quality, segmental image quality of the arteries and PAD segments, venous contamination, and metal artifacts from prostheses, which may compromise quality, were analyzed. The mean overall image quality of each MEI was 2.9 ± 0.7, 3.6 ± 0.6, 3.9 ± 0.3, 4.0 ± 0.2, and 4.0 ± 0.2 from 40 to 80 keV, respectively. The segmental image quality gradually increased from 40 to 70-80 keV until reaching its highest value. Among 295 PAD segments in 68 patients, 40 (13.6%) were scored at 1-2 at 40 keV and 13 (4.4%) were scored at 2 at 50 keV, indicating unsatisfactory image quality due to the indistinguishability between high-contrast areas and arterial calcifications. The segments exhibiting metal artifacts and venous contamination were reduced at 70-80 keV (2.6 ± 1.2, 2.7 ± 0.5) compared with at 40 keV (2.4 ± 1.1, 2.5 ± 0.7). The LE-CTA method using a reconstruction algorithm for MEIs at 70-80 keV can enhance the image quality for PAD evaluation and improve mitigate venous contamination and metal artifacts.

Improved Blood Suppression of Motion-Sensitized Driven Equilibrium in High-Resolution Whole-Brain Vessel Wall Imaging: Comparison of Contrast-Enhanced 3D T1-Weighted FSE with Motion-Sensitized Driven Equilibrium and Delay Alternating with Nutation for Tailored Excitation.

High-resolution vessel wall MR imaging is prone to slow-flow artifacts, particularly when gadolinium shortens the T1 relaxation time of blood. This study aimed to determine the optimal preparation pulses for contrast-enhanced high-resolution vessel wall MR imaging. Fifty patients who underwent both motion-sensitized driven equilibrium and delay alternating with nutation for tailored excitation (DANTE) preparation pulses with contrast-enhanced 3D-T1-FSE were retrospectively included. Qualitative analysis was performed using a 4-grade visual scoring system for black-blood performance in the small-sized intracranial vessels, overall image quality, severity of artifacts, and the degree of blood suppression in all cortical veins as well as transverse sinuses. Quantitative analysis of the M1 segment of the MCA was also performed. The qualitative analysis revealed that motion-sensitized driven equilibrium demonstrated a significantly higher black-blood score than DANTE in contrast-enhanced 3D-T1-FSE of the A3 segment (3.90 versus 3.58, P < .001); M3 (3.72 versus 3.26, P = .004); P2 to P3 (3.86 versus 3.64, P = .017); the internal cerebral vein (3.72 versus 2.32, P < .001); and overall cortical veins (3.30 versus 2.74, P < .001); and transverse sinuses (2.82 versus 2.38, P < .001). SNRlumen, contrast-to noise ratiowall-lumen, and SNRwall in the M1 vessel were not significantly different between the 2 preparation pulses (all, P > .05). Motion-sensitized driven equilibrium demonstrated improved blood suppression on contrast-enhanced 3D-T1-FSE in the small intracranial arteries and veins compared with DANTE. Motion-sensitized driven equilibrium is a useful preparation pulse for high-resolution vessel wall MR imaging to decrease venous contamination and suppress slow-flow artifacts when using contrast enhancement.

Imaging Findings of Peripheral Arterial Disease on Lower-Extremity CT Angiography Using a Virtual Monoenergetic Imaging Algorithm.

Peripheral arterial disease (PAD) is common in elderly patients. Lower-extremity CT angiography (LE-CTA) can be useful for detecting PAD and planning its treatment. PAD can also be accurately evaluated on reconstructed monoenergetic images (MEIs) from low kiloelectron volt (keV) to high keV images using dual-energy CT. Low keV images generally provide higher contrast than high keV images but also feature more severe image noise. The noise-reduced virtual MEI reconstruction algorithm, called the Mono+ technique, was recently introduced to overcome such image noise. Therefore, this pictorial review aimed to present the imaging findings of PAD on LE-CTA and compare low and high keV images with those subjected to the Mono+ technique. We found that, in many cases, the overall and segmental image qualities were better and metal artifacts and venous contamination were decreased in the high keV images.

Optimized enhanced acceleration selective arterial spin labeling (eAccASL) for non-gated and non-enhanced MR angiography of the hands

PurposeEnhanced acceleration selective arterial spin labeling (eAccASL) was introduced as non-enhanced and non-gated magnetic resonance angiography (MRA). This technique has not been applied to hand MRA. The objective of this study was to optimize the eAccASL for MRA of the hands and to investigate the factors for MRA visibility of the hands. MethodsTwenty healthy volunteers were examined on a 1.5 T MR system. To evaluate arterial visualization, we compared four different acceleration-encoding (AENC) values (i.e., 0.12, 0.29, 0.58, and 0.87 m/s2). Image quality score regarding the MRA depiction of the proximal artery (range, 0–10), the distal artery (0–5), and venous contamination (0–5) was evaluated by three radiologists. We measured the peak to peak arterial blood flow velocity (Vpp) measured by phase contrast cine MRI and hand temperature as the factors for arterial visualization. Qualitative scores were compared with Friedman's tests. Spearman's correlation of qualitative scores with Vpp and hand temperature was performed to analyze influencing factors. ResultsFor the distal arterial depiction, scores at AENC 0.12 (median, 9.0) and AENC 0.29 (8.0) were significantly better (both P < 0.0001) than those at AENC 0.87 (5.5). For the proximal arterial depiction, scores at AENC 0.12 (2.25) and AENC 0.29 (2.0) were significantly better (P < 0.001 and P < 0.01, respectively) than those at AENC 0.87 (1.5). Conversely, venous contamination scores at AENC 0.12 (3.0) and AENC 0.29 (3.0) were significantly worse (both P < 0.0001) than those at AENC 0.87 (4.0). There were significantly negative correlations between venous contamination and Vpp at AENC 0.12 (ρ = −0.56, P = 0.01), and 0.29 (ρ = −0.68, P = 0.001), whereas hand temperatures were not significantly correlated with scores (all P > 0.05). ConclusioneAccASL MRA of the hands was optimized by using low AENC values (0.12–0.29 m/s2). Venous contamination may increase with elevation of arterial blood flow.

Optimal placement of the region of interest for bolus tracking on brain computed tomography angiography in Beagle dogs.

This study aimed to determine the optimal placement of the region of interest (ROI) among four anatomical sites—pulmonary artery (PA), pulmonary vein (PV), aortic arch (AA), and carotid artery (CA)—in computed tomography (CT) brain angiography with automatic bolus tracking in healthy beagle dogs. Six beagles were included, and CT brain angiography was performed four times for each dog, to cover each ROI. The scan parameters, amount, and injection rate of the contrast medium were the same. The major intracranial arteries were selected for quantitative and qualitative evaluation: caudal cerebellar artery (CcA), basilar artery (BA), rostral cerebellar artery (RcA), caudal cerebral artery (CCA), middle cerebral artery (MCA), and rostral cerebral artery (RCA). Quantitative evaluation showed significantly higher CT attenuation values for the RcA, CCA, and MCA in the PA group and RcA and MCA in the PV group than in the CA group. Qualitative analysis revealed significantly higher scores for the BA, CCA, and MCA in the PA and PV groups than in the CA group. Venous contamination did not differ significantly among the ROIs, but the mean scores of the AA and CA groups were higher than those of the PA and PV groups. CT brain angiography using bolus tracking in the beagle dogs showed that the ROI should be placed at the PA or PV rather than at the CA for optimal images with strong contrast enhancement of the BA, RcA, CCA, and MCA and minimal venous contamination.

Computed Tomography Angiography in Peripheral Arterial Disease: Comparison of Three Image Acquisition Techniques to Optimize Vascular Enhancement-Randomized Controlled Trial.

Objectives: To prospectively compare three image acquisition techniques in lower extremity CT angiography: the “standard” anterograde technique (SA), the adaptive anterograde technique (AA), and the retrograde acquisition technique (RA).Materials and Methods: Sixty consecutive patients were prospectively enrolled and randomized into three acquisition groups: 20 patients were evaluated with SA, 20 with AA as described by Qanadli et al., and 20 with caudocranial acquisition from the feet to the abdominal aorta (RA). Quantitative image quality was assessed by measuring the intraluminal attenuation at different levels of interest, with a total of 536 levels. Qualitative image quality was assessed by two radiologists in consensus using a Likert scale to rate the arterial enhancement and venous return. For each patient and limb, the presence of occlusive or aneurysmal disease was documented.Results: In quantitative analysis, RA showed lower attenuation values than SA and AA (p < 0.01). AA showed the highest and most homogeneous attenuation along the arterial tree. In qualitative analysis, AA had the lowest rate of non-diagnostic vascular segments (3.9%) compared to SA and RA (4.7 and 13.1%, respectively, p < 0.01). The influence of venous return was significantly different among the different techniques; venous contamination was particularly prevalent at the aortic level with RA (9.4% of patients, 0% with SA and AA, p < 0.01). The presence of stenosis or occlusion had no significant influence on the attenuation values across all levels and acquisition techniques. Conversely, the presence of aneurysmal disease had a significant effect on the luminal attenuation in AA (higher attenuation) and RA (lower attenuation) at the iliac (p = 0.03 and 0.04, respectively) and femoral levels (p = 0.02 and <0.01, respectively).Conclusion: Considering both quantitative and qualitative analysis, AA performed better than SA and RA, providing the highest percentage of optimal vascular enhancement. AA should be recommended as the technique of choice, specifically in the presence of aneurysmal disease. Alternatively, SA can be useful in case of renal failure, as the test bolus is unnecessary. Finally, the increasing availability of fast CT systems will likely overcome the limitations of RA.

Non-contrast-enhanced MR angiography of the foot with flow spoiled-fresh blood imaging (FS-FBI): feasibility study and comparison of different scanning parameters

To evaluate the feasibility of foot arteries using flow-spoiled-fresh blood imaging (FS-FBI) and to investigate how the FS-FBI scanning parameters affect the flow sensitivity and impact the depiction of pedal arteries. The study included 46 young healthy volunteers examined by FS-FBI using 1.5T MRI scanner. Additional FS-FBI examination with different flip angles (FA) of the radiofrequency refocusing pulse and echo time (TE) was performed on 36 volunteers. Two radiologists separately analyzed and graded the venous contamination, image quality, displaying rate, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) values of foot arteries. Multi-sample Friedman test and paired two-sided Student’s t test were used for statistical analysis (P < 0.05). Average image quality and venous contamination score of all arteries was good. The demonstration rate of distal anterior and posterior tibial artery, and lateral plantar artery was 100%. Dorsalis pedis artery, first dorsal metatarsal artery, medial plantar artery, and plantar arch were demonstrated at a rate above 90%. The demonstration rate of medial tarsal artery was 73.9%, whereas arcuate artery was detected with a rate of only 5.4%. Significant differences in image quality, SNR, and CNR of distal arterial area were observed between different FA and TE. Non-contrast-enhanced MR angiography of foot using FS-FBI enables clear separation of veins from arteries, and yields reliable depiction of the foot arterial tree in healthy volunteers. Distal arterial branches of foot can be better depicted by appropriate adjustment of the flow-sensitivity parameters.

Non-Contrast-Enhanced Carotid MRA: Clinical Evaluation of a Novel Ungated Radial Quiescent-Interval Slice-Selective MRA at 1.5T.

Non-contrast-enhanced MRA techniques have experienced a renaissance due to the known correlation between the use of gadolinium-based contrast agents and the development of nephrogenic systemic fibrosis and the deposition of gadolinium in some brain regions. The purpose of this study was to assess the diagnostic performance of ungated non-contrast-enhanced radial quiescent-interval slice-selective MRA of the extracranial supra-aortic arteries in comparison with conventional contrast-enhanced MRA in patients with clinical suspicion of carotid stenosis. In this prospective study, both MRA pulse sequences were performed in 31 consecutive patients (median age, 68.8 years; 19 men). For the evaluation, the cervical arterial system was divided into 35 segments (right and left side). Three blinded reviewers separately evaluated these segments. An ordinal scoring system was used to assess the image quality of arterial segments and the stenosis grading of carotid arteries. Overall venous contamination in quiescent-interval slice-selective MRA was rated as "none" by all readers in 84.9% of cases and in 8.1% of cases in contrast-enhanced MRA (P < .0001). The visualization quality of arterial segments was considered good to excellent in 40.2% for the quiescent-interval slice-selective MRA and in 52.2% for the contrast-enhanced MRA (P < .0001). The diagnostic accuracy of ungated quiescent-interval slice-selective MRA concerning the stenosis grading showed a total sensitivity and specificity of 85.7% and 90.0%, respectively. Ungated quiescent-interval slice-selective MRA can be used clinically as an alternative to contrast-enhanced MRA without a significantly different image quality or diagnostic accuracy for the detection of carotid stenosis at 1.5T.

IPC12. Does Lymphoscintigraphy Correlate to Clinical Presentation in Lymphoedema?

To compare lymphoscintigraphy scan Results, the gold standard of investigation for lymphedema, with clinical presentation. We have collected the data from electronic patient records for patients who had a Lymphoscintigraphy scan from October 1, 2016, to March 31, 2018. The examination protocol involved subcutaneous injection of nanocolloid tracer in first web space in each foot and determining its uptake at the groin at 30 minutes and 2 hours after injection. Uptake of less than 8% at 2 hours was considered abnormal, as was dermal backflow. Uptake of 9% to 14% was considered normal, while uptakes of 19% to 22% were considered accidental venous contamination. Forty-seven patients, with age ranging between 9 and 78 years, underwent a lymphoscintigraphy scan in this time period, 12 of which had uptake of less than 8% in one limb. In 58.33% (n = 7) of these, the lymphoscintigraphy scan result did not correlate with laterality of clinical presentation. Nineteen patients had an uptake of less than 8% in both limbs. Of these in 26.31% (n = 5) the lymphoscintigraphy scan Results did not correlate with laterality of clinical presentation. Sixteen patients had a normal scan. Of these 3 had evidence of venous incompetence in relevant limb(s) but 13 had a normal venous scan and 4 patients had unintentional venous puncture, 2 of which were identified as normal results in a clearly lymphedema case and 2 as greater than 20% tracer uptake. Lymphoscintigraphy does not seem to correlate with laterality of clinical picture and has limited usefulness in clinical decision making on treatment.

Intrahepatic dynamic contrast MR lymphangiography: initial experience with a new technique for the assessment of liver lymphatics.

To describe the technique and report on our initial experience with the use of intrahepatic dynamic contrast magnetic resonance lymphangiography (IH-DCMRL) for evaluation of the lymphatics in patients with hepatic lymphatic flow disorders. This is a retrospective review of the imaging and clinical findings in six consecutive patients undergoing IH-DCMRL. The technique involves injection of a gadolinium contrast agent into the intrahepatic lymphatic ducts followed by imaging of the abdomen and chest with both heavily T2-weighted imaging and dynamic time-resolved imaging. In six consecutive patients, IH-DCMRL was technically successful. There were four patients with protein-losing enteropathy (PLE) and two with ascites in this study. In the four patients with PLE, IH-DCMRL demonstrated hepatoduodenal connections with leak of contrast into the duodenal lumen not seen by conventional lymphangiography. In one patient with ascites, IH-DCMRL demonstrated lymphatic leakage into the peritoneal cavity not seen by intranodal lymphangiography. In the second patient with ascites, retrograde lymphatic perfusion of mesenteric lymphatic networks and nodes was seen. Venous contamination was seen in two patients. No biliary contamination was identified. There were no short-term complications. IH-DCMRL is a cross-sectional technique which successfully evaluated hepatic lymphatic flow disorders and warrants further investigation. • Intrahepatic dynamic contrast magnetic resonance lymphangiography (IH-DCMRL) is a new imaging technique to evaluate hepatic lymphatic flow disorders such as protein-losing enteropathy. • In comparison to conventional liver lymphangiography, IH-DCMRL offers a 3D imaging technique and better distal lymphatic contrast distribution and does not use ionizing radiation.

Pesquisa de endotoxinas em água de hemodiálise

Introduction: Chronic kidney disease is characterized by loss of kidney function leading to a physiological and biological functional imbalance. One of the treatments necessary for the chronic renal patient is hemodialysis. Water quality is critical to reducing patient risk. Resolution RDC n. 11, of March 13th, 2014, from Brazilian Health Regulatory Agency (Anvisa) establishesd the search for endotoxins, as venous contamination by endotoxins may cause various problems in the patients’ health. Objective: To identify endotoxins in purified water for hemodialysis. Method: This is a Quantitative Descriptive Cross-sectional Study to verify the presence of endotoxins in 126 water samples collected at two points (post-reverse osmosis and reuse room) at six renal substitution therapy clinics, by the State Sanitary Surveillance, and analyzed in the LACEN, in Campo Grande, MS, in 2016. Results: Of the 68 water samples collected after the reverse osmosis process, three (4.41%), and of the 58 samples collected in the reuse room, six (10.52%) presented endotoxin results above the amount allowed by the legislation (0.25 EU\mL). Conclusions: Results indicate membrane involvement of the reverse osmosis process, and, or presence of biofilm in the pipes, and inefficiency of the cleaning process of the reservoir, pipes, and machines disinfection process.

A Factor Increasing Venous Contamination on Bolus Chase Three-dimensional Magnetic Resonance Imaging: Charcot Neuroarthropathy.

Background:The study aimed to evaluate the ratio of venous contamination in diabetic cases without foot lesion, with foot lesion and with Charcot neuroarthropathy (CN).Materials and Methods:Bolus-chase three-dimensional magnetic resonance (MR) of 396 extremities of patients with diabetes mellitus was analyzed, retrospectively. Extremities were divided into three groups as follows: diabetic patients without foot ulcer or Charcot arthropathy (Group A), patients with diabetic foot ulcers (Group B) and patients with CN accompanying diabetic foot ulcers (Group C). Furthermore, amount of venous contamination classified as no venous contamination, mild venous contamination, and severe venous contamination. The relationship between venous contamination and extremity groups was investigated.Results:Severe venous contamination was seen in Group A, Group B, and Group C, 5.6%, 15.2%, and 34.1%, respectively. Statistically significant difference was seen between groups with regard to venous contamination.Conclusion:Venous contamination following bolus chase MR was higher in patients with CN.

Abstract WP401: Residual Shunting Post PFO Closure is Associated With Increased Long-term Risk of Recurrent Stroke

Background: Patent foramen ovale (PFO) is an independent risk factor for ischemic stroke, and recent clinical trials have shown long-term benefit of PFO closure. We previously found PFO may increase the risk of stroke due to right-to-left shunting, resulting in venous contamination of arterial circulation, with elevated neurovascular mediators such as homocysteine. However, in clinical practice, residual blood shunting can be observed in ~10% of patients post PFO closure, with unclear significance. Here we prospectively investigated the long-term influence of residual shunting on patient outcome. Method: 1018 PFO stroke patients s/p PFO closure from several medical centers were prospectively recruited in accordance with IRB protocol and followed up to 7 years. Result: While closure rate at our center is much lower (&lt;5%), overall closure rate of patients from all major referral centers range between 5-14%. Patients with compete PFO closure (86%) developed higher event-free probability from recurrent TIA/stroke compared to those with residual shunting (14%) (Figure1A, p = 0.001). The risk of recurrent stroke depended on residual shunt size with lower event-free probability in larger shunting (Figure 1B, p = 0.002). Conclusion: Consistent with clinical trials, our prospective observational study suggests complete PFO closure results in lower risk of stroke recurrence. Patients with residual shunting (incomplete PFO closure) may face continued risk, though the overall risk of stroke recurrence is very low. PFO-related shunting appears to be critical in the pathophysiology of recurrent stroke.