Venous Contamination Research Articles

Incidence of central venous catheter hub contamination

PurposeTo investigate microorganisms causing central venous catheter contamination and how this contamination differs across different catheter metrics. Materials and methodsAfter obtaining IRB approval and informed consent, 830 cultures were prospectively obtained from 45 ICU patients with central venous catheter or peripherally inserted central catheter. Bacterial colonies were identified by mass spectrometry. ResultsBacterial contamination of central catheter hubs occurred 44% of the time in this study in the ICU setting. Coagulase-positive staphylococci cultures had higher median (±interquartile range) CFUs (12±232) versus coagulase-negative (3±10) and other bacteria (1±3; P<0.001). Bacterial contamination was associated with various metrics. Higher incidence (P<0.05) of coagulase-positive staphylococci cultures was associated with hub-only connections (a “hub” being a female connection; 10.9% vs. 7.9% male connections), connections without a manifold (1lumen device that mixes multiple infusions together; 9.7% vs. 0% with manifold); and central venous pressure monitoring connections (25.8% vs. 7.1% without). Internal jugular sites (10.0% vs. 2.7% femoral, 6.2% PICC, P=0.031) and medial lumens of triple lumen catheters (11.9% vs. 5.6% distal, 7.0% proximal, P=0.049) had increased incidence of higher bacteria loads (>15 CFUs). ConclusionsThis study found a high incidence of central access catheter hub bacterial contamination, which correlated with positive blood cultures in 2 of 3 total bacteremia cases identified in the 45 patients.

A systematic review of waterborne infections from nontuberculous mycobacteria in health care facility water systems.

Healthcare-acquired infections are an increasing problem for health care providers and policy makers. Water is an overlooked source of infectious microorganisms in health care facilities. Waterborne nontuberculous mycobacteria (NTM) are ubiquitous, and particularly problematic in health care facility water systems, and cause a variety of diseases. The purpose of this review is to assess health care associated NTM infections from health care facility water systems. We documented susceptible populations, modes of transmission, and the median attack rate (e.g. patients infected per patients exposed). We aimed to identify transmission risk factors and inform evidence-based policies for infection control and prevention. We searched Embase, PubMed, Web of Science and clinicaltrials.gov without date restrictions. English language articles with original data on NTM waterborne infections in health care settings were included. Randomized controlled trials, descriptive studies (case reports, case series), case-control studies, cohort studies, cross-sectional surveys, and quasi-experimental studies on nosocomial waterborne infections were included. Three investigators independently screened titles and abstracts for relevant articles, and one screened full-text articles. Data were extracted by one investigator, and a second confirmed accuracy for 10% of results. We included 22 observational studies. Immunocompromised, post-surgical, and hemodialysis patients were commonly affected populations. A range of exposure routes such as uncovered central venous catheters (CVCs), wound exposure, and contamination during surgical procedures was reported. The median attack rate was 12.1% (interquartile range, 11-27.2). Waterborne NTM infection affects susceptible patients through common, preventable exposure routes. Effective prevention strategies will require both medical and environmental health expertise, and inter-professional cooperation will optimize these efforts.

Evaluation of velocity-sensitized and acceleration-sensitized NCE-MRA for below-knee peripheral arterial disease.

To evaluate the diagnostic performance of velocity- and acceleration-sensitized noncontrast-enhanced magnetic resonance angiography (NCE-MRA) of the infrageniculate arteries using contrast-enhanced MRA (CE-MRA) as a reference standard. Twenty-four patients with symptoms of peripheral arterial disease were recruited. Each patient's infrageniculate arterial tree was examined using a velocity-dependent flow-sensitized dephasing (VEL-FSD) technique, an acceleration-dependent (ACC-FSD) technique, and our conventional CE-MRA technique performed at 1.5T. The images were independently reviewed by two experienced vascular radiologists, who evaluated each vessel segment to assess visibility, diagnostic confidence, venous contamination, and detection of pathology. In all, 432 segments were evaluated by each of the three techniques by each reader in total. Overall diagnostic confidence was rated as moderate or high in 98.5% of segments with CE-MRA, 92.1% with VEL-FSD, and 79.9% with ACC-FSD. No venous contamination was seen in 96% of segments with CE-MRA, 72.2% with VEL-FSD, and 85.8% with ACC-FSD. Per-segment, per-limb, and per-patient sensitivities for detecting significant stenotic disease were 63.4%, 73%, and 92%, respectively, for ACC-FSD, and 65.3%, 87.2%, and 96% for VEL-FSD, and as such no significant statistical change was detected using McNemar's chi-squared test with P-values of 1.00, 0.13, and 0.77 obtained, respectively. Flow-dependent NCE-MRA techniques may have a role to play in evaluation of patients with peripheral vascular disease. Increased sensitivity of a velocity-based technique compared to an acceleration-based technique comes at the expense of greater venous contamination. 2J. Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1846-1853.

Implantable venous ports in pediatric oncology: experience of single institution in Russia.

To review our experience with implantable venous port-systems (IVPs) in pediatric cancer patients. From 2010 to 2015 we were monitoring the treatment of 163 children (aged 3 months to 17 years) with oncologic diseases. These patients underwent venous port implantations. During insertion of 163 IVPs the following complications and technical difficulties were present: unintended puncture of the common carotid artery (CCA) during the puncture of the internal jugular vein (IJV) - 7 cases (4.3%); retrograde positioning of the distal end of the guidewire in the IJV - 17 cases (14.4%); placement of the distal end of the guidewire into the punctured subclavian vein (SV) - 12 cases (7.6%); difficulties driving the guidewire into the IJV after successful puncture - 15 cases (9.3%). The use of 163 IVPs was complicated by the following: venous port contamination - 4 cases (2.5%); occlusion of the IVPs by a clot - 8 cases (5%); withdrawal of the Huber needle bevel from the port chamber - 22 cases (13.6%); subcutaneous fat layer thinning above the port chamber - 3 cases (1.7%). There are many complications, but they can be reduced by proper choice of materials and methodology.

Venous Access in the Treatment of Children with Cancer: Results of A 10-Year Multicenter Study

Introduction. Chemotherapy is the definitive treatment for children with cancer. Intravenous administration is the most common method of chemotherapy, since most chemo drugs are easily absorbed through the blood. Thus a long-term venous access is one of the most important and urgent aims of pediatric oncology. Materials and methods . A total of 246 patients aged 2 months to 17 years were included in the analyses. Implanted venous access port systems (IVAPS) implantation was performed in all the patients during the period of 2006-2015. Results . We observe the following complications and technical difficulties in 42 (17%) patients: accidental carotid artery puncture during attempted internal jugular vein (IJV) puncture — 16 (6.5%) cases, retrograde positioning of the distal end of the guidewire in the IJV — 21 (8,5%) cases; insertion of guide wire's distal tip into the punctured SV — 12 (4,9%) cases; difficulties during catheter advancement into the IJV after successful puncture — 26 (10,6%) cases. The following complications were detected venous port contamination — 17 cases (6,9%); occlusion of the IVAPS by a clot — 34 cases (13,8%); subcutaneous fat layer thinning above the port chamber — 2 cases (0,8%). Conclusion . Complications reported in our study (75 cases) were not fatal, mostly preventable, and have not led to protocol violations in the treatment of children with cancer. However, it should be highlighted that there is a need in further training of nurses and doctors in order to disseminate the proposed procedures in other clinics of the Russian Federation and reduce the number of operational complications.

Венозный доступ при лечении детей с онкологическими заболеваниями: результаты 10-летнего мультицентрового исследования

Introduction. Chemotherapy is the definitive treatment for children with cancer. Intravenous administration is the most common method of chemotherapy, since most chemo drugs are easily absorbed through the blood. Thus a long-term venous access is one of the most important and urgent aims of pediatric oncology. Materials and methods . A total of 246 patients aged 2 months to 17 years were included in the analyses. Implanted venous access port systems (IVAPS) implantation was performed in all the patients during the period of 2006-2015. Results . We observe the following complications and technical difficulties in 42 (17%) patients: accidental carotid artery puncture during attempted internal jugular vein (IJV) puncture — 16 (6.5%) cases, retrograde positioning of the distal end of the guidewire in the IJV — 21 (8,5%) cases; insertion of guide wire's distal tip into the punctured SV — 12 (4,9%) cases; difficulties during catheter advancement into the IJV after successful puncture — 26 (10,6%) cases. The following complications were detected venous port contamination — 17 cases (6,9%); occlusion of the IVAPS by a clot — 34 cases (13,8%); subcutaneous fat layer thinning above the port chamber — 2 cases (0,8%). Conclusion . Complications reported in our study (75 cases) were not fatal, mostly preventable, and have not led to protocol violations in the treatment of children with cancer. However, it should be highlighted that there is a need in further training of nurses and doctors in order to disseminate the proposed procedures in other clinics of the Russian Federation and reduce the number of operational complications.

Improved receiver arrays and optimized parallel imaging accelerations applied to time-resolved 3D fluoroscopically tracked peripheral runoff CE-MRA

ObjectivesThree-station stepping-table time-resolved 3D contrast-enhanced magnetic resonance angiography has conflicting demands in the need to limit acquisition time in proximal stations to match the speed of the advancing contrast bolus and in the distal-most station to avoid venous contamination while still providing clinically useful spatial resolution. This work describes improved receiver coil arrays which address this issue by allowing increased acceleration factors, providing increased spatial resolution per unit time. Materials and methodsReceiver coil arrays were constructed for each station (pelvis, thigh, calf) and then integrated into a 48-element array for three-station peripheral CE-MRA. Coil element sizes and array configurations for these three stations were designed to improve SENSE-type parallel imaging taking advantage of an increase in coil count for all stations versus the previous 32 channel capability. At each station either acceleration apportionment or optimal CAIPIRINHA selection was used to choose the optimum acceleration parameters for each subject. Results were evaluated in both single- and multi-station studies. ResultsSingle-station studies showed that SENSE acceleration in the thigh station could be readily increased from R=8 to R=10, allowing reduction of the frame time from 2.5 to 2.1s to better image the typically rapidly advancing bolus at this station. Similarly, the improved coil array for the calf station permitted acceleration increase from R=8 to R=12, providing a 4.0 vs. 5.2s frame time. Results in three-station studies suggest an improved ability to track the contrast bolus in peripheral CE-MRA. ConclusionsModified receiver coil arrays and individualized parameter optimization have been used to provide improved acceleration at all stations in multi-station peripheral CE-MRA and provide high spatial resolution with frame times as short as 2.1s.

Segmented TOF at 7 T MRI: Technique and clinical applications

PurposeTime-of-flight (TOF) MR angiography has an advantage of contrast and resolution in ultra-high field (7T) MRI systems. However, increased specific absorption rate (SAR) prohibits the application of spatial saturation band, leading to venous contamination in maximum intensity projection (MIP) images. MethodsA segmented k-space filling scheme with sparse venous saturation pulses was developed for 7T TOF-MRA. The effectiveness of the segmented TOF sequence was verified by Bloch equation simulation and experiments on 3T. The protocol on 7T was optimized and applied for healthy volunteers and patients with vascular diseases. ResultsSegmented TOF achieved equivalent contrast and venous suppression effect as conventional methods, while SAR values had a remarkable reduction and obeyed the limit of a 7T MRI system. The decreased number of saturation pulses allowed shorter acquisition time than existing solutions. The comparison of segmented TOF and conventional TOF revealed flow direction in vascular diseases. ConclusionSegmented TOF is proved to be a time-efficient way to achieve high-resolution angiograms without venous contamination at ultra-high field. The sequence holds strong promise for non-contrast clinical diagnosis on cerebrovascular diseases.

Optimizing computed tomography pulmonary angiography using right atrium bolus monitoring combined with spontaneous respiration.

CT pulmonary angiography (CTPA) aims to provide pulmonary arterial opacification in the absence of significant pulmonary venous filling. This requires accurate timing of the imaging acquisition to ensure synchronization with the peak pulmonary artery contrast concentration. This study was designed to test the utility of right atrium (RA) monitoring in ensuring optimal timing of CTPA acquisition. Sixty patients referred for CTPA were divided into two groups. Group A (n = 30): CTPA was performed using bolus triggering from the pulmonary trunk, suspended respiration and 70 ml of contrast agent (CA). Group B (n = 30): CTPA image acquisition was triggered using RA monitoring with spontaneous respiration and 40 ml of CA. Image quality was compared. Subjective image quality, average CT values of pulmonary arteries and density difference between artery and vein pairs were significantly higher whereas CT values of pulmonary veins were significantly lower in group B (all P < 0.05). There was no significant difference between the groups in the proportion of subjects where sixth grade pulmonary arteries were opacified (P > 0.05). RA monitoring combined with spontaneous respiration to trigger image acquisition in CTPA produces optimal contrast enhancement in pulmonary arterial structures with minimal venous filling even with reduced doses of CA. • Bolus tracking (BT) with pulmonary trunk monitoring is widely used in CTPA. • Pulmonary venous contamination is a disadvantage of BT due to transition delay time. • Right atrium monitoring with spontaneous respiration can optimize CTPA. • It produces optimal contrast enhancement in pulmonary arteries with minimal venous filling. • The contrast dose was significantly reduced.

High-resolution postcontrast time-of-flight MR angiography of intracranial perforators at 7.0 Tesla.

Background and PurposeDifferent studies already demonstrated the benefits of 7T for precontrast TOF-MRA in the visualization of intracranial small vessels. The aim of this study was to assess the performance of high-resolution 7T TOF-MRA after the administration of a gadolinium-based contrast agent in visualizing intracranial perforating arteries.Materials and MethodsTen consecutive patients (7 male; mean age, 50.4 ± 9.9 years) who received TOF-MRA at 7T after contrast administration were retrospectively included in this study. Intracranial perforating arteries, branching from the parent arteries of the circle of Willis, were identified on all TOF-MRA images. Provided a TOF-MRA before contrast administration was present, a direct comparison between pre- and postcontrast TOF-MRA was made.ResultsIt was possible to visualize intracranial perforating arteries branching off from the entire circle of Willis, and their proximal branches. The posterior cerebral artery (P1 and proximal segment of P2) appeared to have the largest number of visible perforating branches (mean of 5.1 in each patient, with a range of 2–7). The basilar artery and middle cerebral artery (M1 and proximal segment M2) followed with a mean number of 5.0 and 3.5 visible perforating branches (range of 1–9 and 1–8, respectively). Venous contamination in the postcontrast scans sometimes made it difficult to discern the arterial or venous nature of a vessel.ConclusionHigh-resolution postcontrast TOF-MRA at 7T was able to visualize multiple intracranial perforators branching off from various parts of the circle of Willis and proximal intracranial arteries. Although confirmation in a larger study is needed, the administration of a contrast agent for high-resolution TOF-MRA at 7T seems to enable a better visualization of the distal segment of certain intracranial perforators.

Estudio de concordancia diagnóstica entre la angiorresonancia magnética y la arteriografía en la isquemia crítica de miembros inferiores

ObjectivesTo evaluate the validity of 3-D magnetic resonance angiography (MRA) with gadolinium and compare the diagnostic results with digital subtraction angiography (DEA) in patients with critical limb ischemia. MaterialThe study consisted of 40 patients diagnosed with lower limb critical ischemia treated using an endovascular technique in our unit between September 2012 and September 2014. There were 28 males. The mean age was 69 years, and 24 of them had more than 3 vascular risk factors. They had Rutherford scores of 4 (n=19, 5 (n=16), and 6 (n=5). MethodsA retrospective evaluation was performed on the intra-operative angiography images, comparing them with the MRA images obtained before the intervention (no more than 3 months between them). The arterial tree was divided into 9 segments, grouped in the iliac, femoropopliteal and distal sectors. The sensitivity (S), specificity (Sp), positive and negative predictive values, and kappa coefficient (K) for each segment, as well as overall. ResultsThe overall S and Sp was 88.3 and 89%, respectively. In the iliac sector, it was 93 and100%, in the femoropopliteal, 93 and 92%, and in the distal 84 and 65%, respectively. The overall kappa index was 0.76, with 0.94 in the iliac sector 0.88 in the femoropopliteal, and 0.47 in the distal. The analysis of 10% of the distal sectors was impossible, due to venous contamination in the MRA. ConclusionsMRA may be considered as a valid alternative to DSA in the iliac-femoropopliteal sector. At distal level, the MRA results should be interpreted with caution due to the decrease in the concordance index with the gold standard.

Intra-vascular blood velocity and volumetric flow rate calculated from dynamic 4D CT angiography using a time of flight technique.

We examine a time of flight (TOF) approach for the analysis of contrast enhanced 4D volumetric CT angiography scans to derive and display blood velocity in arteries. Software was written to divide blood vessels into a series of cross sections and to track contrast bolus TOF along the central vessel axis, which was defined by a user, from 4D CT source data. Time density curves at each vessel cross section were fit with quadratic, Gaussian, and gamma variate functions to determine bolus time to peak (TTP). A straight line was used to plot TTP versus vessel path length for all three functions and the slope used to calculate intraluminal velocity. Software was validated in a simulated square channel and non-pulsatile flow phantom prior to the calculation of blood velocity in the major cerebral arteries of 8 normal patients. The TOF algorithm correctly calculates intra-luminal fluid velocity in eight flow conditions of the CT flow phantom where quadratic functions were used. Across all conditions, in phantoms and in vivo, the success of calculations depended strongly on having a sufficiently long path length to make measurements and avoiding venous contamination. Total blood flow into the brain was approximately 17 % of a normal 5 L cardiac output. The technique was explored in vivo in a patient with subclavian steal syndrome, in the pulmonary arteries and in the iliac artery from clinical 4D CT source data. Intravascular blood velocity and flow may be calculated from 4D CT angiography using a TOF approach.

Image Quality and Radiation Dose of Lower Extremity CT Angiography Using 70 kVp, High Pitch Acquisition and Sinogram-Affirmed Iterative Reconstruction

ObjectivesThe purpose of this study was to assess image quality and radiation dose of lower extremity CT angiography (CTA) with 70 kVp, high pitch acquisition and sinogram-affirmed iterative reconstruction (SAFIRE).MethodsLower extremity CTAs were performed on 44 patients: 22 patients were examined using protocol A (120 kVp, pitch of 0.85 and 120 ml of contrast agent on a first-generation dual-source CT) (120 kVp group) and 22 patients were evaluated with protocol B (70 kVp, pitch of 2.2 and 80 ml of contrast agent on a second-generation dual-source CT) (70 kVp group). Images from the 120 kVp group were reconstructed with filtered back projection (FBP) and images from the 70 kVp group with SAFIRE. The attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists subjectively assessed image quality of lower extremity arteries, plantar arterial enhancement and venous contamination of all patients. Radiation dose was compared between the two groups.ResultsHigher mean intravascular attenuation was obtained in the 70 kVp group (70 vs. 120 kVp group, 555.4±83.4 HU vs. 300.9±81.4 HU, P<0.001), as well as image noise (20.0±2.8 HU vs. 17.5±3.2 HU, P = 0.010), SNR (32.0±7.0 vs. 19.1±6.9, P<0.001) and CNR (28.1±6.6 vs 15.9±6.3, P<0.001). No difference in subjective image quality and plantar arterial enhancement was found between 120 kVp group and 70 kVp group (all P>0.05). The venous contamination score was 1.5±0.8 for 120 kVp group while no venous contamination was found in 70 kVp group. The inter-observer agreement was moderate to good for both groups (0.515∼1, P<0.001). The effective dose was lower in 70 kVp group (0.3±0.1 mSv) than in 120 kVp group (1.6±0.7 mSv)(P<0.001).ConclusionsLower extremity CTA using 70 kVp, high pitch acquisition and SAFIRE, except increasing imaging noise, allows for lower radiation dose and contrast material volume without compromising image quality.

Phase based venous suppression in resting-state BOLD GE-fMRI

Resting-state functional MRI (RS-fMRI) is a widely used method for inferring connectivity between brain regions or nodes. As with task-based fMRI, the spatial specificity of the connectivity maps can be distorted by the strong biasing effect of the BOLD signal in macroscopic veins. In RS-fMRI this effect is exacerbated by the temporal coherences of physiological origin between large veins that are widely distributed in the brain. In gradient echo based EPI, used for the vast majority of RS-fMRI, macroscopic veins that carry BOLD-related changes exhibit a strong phase response. This allows for post-processing identification and removal of venous signals using a phase regressor technique. Here, we employ this approach to suppress macrovascular venous contributions in high-field whole-brain RS-fMRI data sets, resulting in significant changes to both the spatial localization of the networks and the correlations between the network nodes. These effects were observed at both the individual and group analysis level, suggesting that venous contamination is a confounding factor for RS-fMRI studies even at relatively low image resolutions. Suppression of the macrovascular signal using the phase regression approach may therefore help to better identify, delineate, and interpret the true structure of large-scale brain networks.

Impact of source data on the interpretation of contrast-enhanced magnetic resonance angiography of the lower limbs.

BackgroundThe primary purpose of this study is to examine whether use of source data is effective in increasing the number of arterial segments that can be interpreted from maximum intensity projections of lower limb MR angiograms. Correlation between sites of arterial disease and venous contamination was also measured. Interpretation of source data is performed routinely by radiologists, but the value of this has not been well studied with randomized studies.ResultsThe proportion of segments visible above the knee was 87% using maximal intensity projection alone (MIP) and 88% when the MIP was combined with source data. The proportions were 67% for MIP and 72% for MIP plus source data below the knee. There was substantial agreement between presence of arterial disease and venous contamination in the calf and thigh.ConclusionThe use of source data increases the number of assessable segments, but not individuals, by a statistically significant but small amount (1.2%, p <0.05). This study supports the association between arterial disease and venous contamination.

Continuously moving table aorto-iliofemoral run-off contrast-enhanced magnetic resonance angiography: image quality analysis in comparison to the multistep acquisition

Optimal vessel contrast is a prerequisite for vascular imaging. Consecutive stationary imaging of multiple fields of view is contrary to the continuous contrast material passage through the vascular tree. A continuous acquisition of a magnetic resonance (MR) sequence might overcome this limitation. To investigate the image quality of a continuously moving table (CMT) acquisition compared with the established multistep approach for contrast-enhanced magnetic resonance angiography (CE-MRA) of the aorto-iliofemoral run-off. Institutional review board approved this retrospective interindividual study of 60 consecutive patients referred to CE-MRA for peripheral arterial disease. Thirty patients underwent CE-MRA using the routine multistep acquisition and 30 patients were scanned using the CMT technique at 1.5 Tesla. All patients received a fixed contrast dose of 25 mL gadoterate meglumine. A quantitative analysis was performed to assess the relative contrast of 10 vascular segments from the proximal abdominal aorta to the distal calf arteries. A qualitative evaluation of three separate vascular regions (abdomen and pelvis, thighs, and calves) was performed. Two radiologists graded independently arterial vessel conspicuity, venous contamination, presence of artifacts, and diagnostic confidence on a 4-point scale. Overall scan time, including all localizer scans, was recorded. Statistical differences were tested using the Wilcoxon signed-rank test with Bonferroni correction. No significant differences were found between the continuously moving table acquisition and the multistep acquisition with regard to the relative vascular contrast and the qualitative image criteria. The agreement between both readers was significant (Kendall tau rank correlation coefficient, 0.373). The absolute reader agreement was 71.4%. The mean overall scan time was 12 min 44 s for the CMT protocol and 21 min 41 s for the multistep protocol. Aorto-iliofemoral run-off CE-MRA acquired with CMT technique provides a high image quality equivalent to a multistep technique at an overall scan time reduction of 41.3%.

Three-Station Three-dimensional Bolus-Chase MR Angiography with Real-time Fluoroscopic Tracking

To determine the feasibility of using real-time fluoroscopic tracking for bolus-chase magnetic resonance (MR) angiography of peripheral vasculature to image three stations from the aortoiliac bifurcation to the pedal arteries. This prospective study was institutional review board approved and HIPAA compliant. Eight healthy volunteers (three men; mean age, 48 years; age range, 30-81 years) and 13 patients suspected of having peripheral arterial disease (five men; mean age, 67 years; age range, 47-81 years) were enrolled and provided informed consent. All subjects were imaged with the fluoroscopic tracking MR angiographic protocol. Ten patients also underwent a clinical computed tomographic (CT) angiographic runoff examination. Two readers scored the MR angiographic studies for vessel signal intensity and sharpness and presence of confounding artifacts and venous contamination at 35 arterial segments. Mean aggregate scores were assessed. The paired MR angiographic and CT angiographic studies also were scored for visualization of disease, reader confidence, and overall diagnostic quality and were compared by using a Wilcoxon signed rank test. Real-time fluoroscopic tracking performed well technically in all studies. Vessel segments were scored good to excellent in all but the following categories: For vessel signal intensity and sharpness, the abdominal aorta, iliac arteries, distal plantar arteries, and plantar arch were scored as fair to good; and for presence of confounding artifacts, the abdominal aorta and iliac arteries were scored as fair. The MR angiograms and CT angiograms did not differ significantly in any scoring category (reader 1: P = .50, .39, and .39; reader 2: P = .41, .61, and .33, respectively). CT scores were substantially better in 20% (four of 20) and 25% (five of 20) of the pooled evaluations for the visualization of disease and overall image quality categories, respectively, versus 5% (one of 20) for MR scores in both categories. Three-station bolus-chase MR angiography with real-time fluoroscopic tracking provided high-spatial-resolution arteriograms of the peripheral vasculature, enabled precise triggering of table motion, and compared well with CT angiograms.

3D CT cerebral angiography technique using a 320-detector machine with a time–density curve and low contrast medium volume: Comparison with fixed time delay technique

To describe a cerebral computed tomography angiography (CTA) technique using a 320-detector CT machine and a small contrast medium volume (35 ml, 15 ml for test bolus). Also, to compare the quality of these images with that of the images acquired using a larger contrast medium volume (90 or 120 ml) and a fixed time delay (FTD) of 18 s using a 16-detector CT machine. Cerebral CTA images were acquired using a 320-detector machine by synchronizing the scanning time with the time of peak enhancement as determined from the time-density curve (TDC) using a test bolus dose. The quality of CTA images acquired using this technique was compared with that obtained using a FTD of 18 s (by 16-detector CT), retrospectively. Average densities in four different intracranial arteries, overall opacification of arteries, and the degree of venous contamination were graded and compared. Thirty-eight patients were scanned using the TDC technique and 40 patients using the FTD technique. The arterial densities achieved by the TDC technique were higher (significant for supraclinoid and basilar arteries, p < 0.05). The proportion of images deemed as having "good" arterial opacification was 95% for TDC and 90% for FTD. The degree of venous contamination was significantly higher in images produced by the FTD technique (p < 0.001%). Good diagnostic quality CTA images with significant reduction of venous contamination can be achieved with a low contrast medium dose using a 320-detector machine by coupling the time of data acquisition with the time of peak enhancement.

Impact of Time-Resolved MRA on Diagnostic Accuracy in Patients With Symptomatic Peripheral Artery Disease of the Calf Station

The purpose of this article is to evaluate the added diagnostic accuracy of time-resolved MR angiography (MRA) of the calves compared with continuous-table-movement MRA in patients with symptomatic lower extremity peripheral artery disease (PAD) using digital subtraction angiography (DSA) correlation. Eighty-four consecutive patients with symptomatic PAD underwent a low-dose 3-T MRA protocol, consisting of continuous-table-movement MRA, acquired from the diaphragm to the calves, and an additional time-resolved MRA of the calves; 0.1 mmol/kg body weight (bw) of contrast material was used (0.07 mmol/kg bw for continuous-table-movement MRA and 0.03 mmol/kg bw for time-resolved MRA). Two radiologists rated image quality on a 4-point scale and stenosis degree on a 3-point scale. An additional assessment determined the degree of venous contamination and whether time-resolved MRA improved diagnostic confidence. The accuracy of stenosis gradation with continuous-table-movement and time-resolved MRA was compared with that of DSA as a correlation. Overall diagnostic accuracy was calculated for continuous-table-movement and time-resolved MRA. Median image quality was rated as good for 578 vessel segments with continuous-table-movement MRA and as excellent for 565 vessel segments with time-resolved MRA. Interreader agreement was excellent (κ = 0.80-0.84). Venous contamination interfered with diagnosis in more than 60% of continuous-table-movement MRA examinations. The degree of stenosis was assessed for 340 vessel segments. The diagnostic accuracies (continuous-table-movement MRA/time-resolved MRA) combined for the readers were obtained for the tibioperoneal trunk (84%/93%), anterior tibial (69%/87%), posterior tibial (85%/91%), and peroneal (67%/81%) arteries. The addition of time-resolved MRA improved diagnostic confidence in 69% of examinations. The addition of time-resolved MRA at the calf station improves diagnostic accuracy over continuous-table-movement MRA alone in symptomatic patients with PAD.

Improved artery–vein separation with acceleration‐dependent preparation for non–contrast‐enhanced magnetic resonance angiography

To compare the use of acceleration-dependent and velocity-dependent flow-preparation for non-contrast-enhanced magnetic resonance angiography (NCE-MRA), investigating both image quality and the ability to discriminate between arteries and veins. We develop an acceleration-dependent NCE-MRA method known as acceleration dependent vascular anatomy for non-contrast-enhanced MRA (ADVANCE-MRA). Acceleration-dependent and velocity-dependent images were acquired using a constant and pulsatile flow-phantom and from the lower legs of six healthy volunteers and one patient with peripheral vascular disease. The volunteer images were assessed both by quantitative signal measurements and qualitative scoring by a radiologist. In the phantom, acceleration-dependent preparation depicted pulsatile but not constant flow, while velocity-dependent preparation depicted both. In the volunteers and the patient, the velocity-dependent preparation was unable to separate the arterial and venous signals completely, with some overlap of arterial and venous signals for all acquired flow sensitizations whereas the acceleration-dependent preparation gave complete artery-vein separation over a wide range of flow sensitizations. Acceleration-dependent preparation received the best overall qualitative scores for arterial image quality and venous contamination. Acceleration-dependent NCE-MRA improves arterial image quality and reduces venous contamination, compared with velocity-dependent NCE-MRA, and warrants further investigation in patients.