Power Injector Research Articles

A Dual Operation of PV-Statcom as Reactive Power Compensator and Active Power Injector in Grid Tie System: Power Quality

A Dual Operation of PV-Statcom as Reactive Power Compensator and Active Power Injector in Grid Tie System: Power Quality

Effects of a TAFI-Inhibitor Combined with a Suboptimal Dose of rtPA in a Murine Thromboembolic Model of Stroke

Background: Since thrombolysis is the only approved intervention for ischemic stroke, improving its efficacy and safety is a therapeutic aim of considerable interest. The activated form of thrombin activatable fibrinolysis inhibitor (TAFI) has antifibrinolytic effects, and inhibition of TAFI might thus favor recanalization. The present study compared efficacy between TAFI inhibition alone and TAFI inhibition in combination with rtPA at a suboptimal dose, in a murine model of thromboembolic stroke. Methods: Focal ischemia was induced in mice by thrombin injection in the middle cerebral artery. Animals were placed within the magnet immediately after surgery for baseline MRI (H0). MRI examination comprised diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and T2-weighted imaging (T2-WI). Animals were randomly assigned to 1 of 5 treatment groups: saline, rtPA 5 mg/kg (tPA⁵: suboptimal or low dose), rtPA 10 mg/kg (tPA¹⁰: standard dose), TAFI-I 100 mg/kg (TAFI-I), and rtPA 5 mg/kg + TAFI-I 100 mg/kg (tPA⁵ + TAFI-I). Treatments were administered inside the magnet, via a catheter placed in the tail vein, using a power injector, as 10% bolus and 90% infusion over a period of 20 min. MRI examination was repeated at 3 h (H3) and 24 h (H24) after surgery. Therapeutic benefit was evaluated by: (1) improvement of reperfusion and (2) reduction in final lesion size. Microhemorrhages were assessed as black spots on T2-WI at H24. Animals were sacrificed after the last MR examination. The surgeon and all investigators were blinded to treatment allocation. Results: A total of 104 mice were operated on. Forty four of these were excluded from the study and 27 from the analysis, according to a priori defined criteria (no lesion or no mismatch), leading to the following distribution: saline (n = 6), tPA⁵ (n = 8), tPA¹⁰ (n = 7), TAFI-I (n = 7), and TAFI-I + tPA⁵ (n = 5). Standard-dose rtPA treatment (tPA¹⁰) significantly improved lesion regression between H0 and H24 compared to saline (-57 ± 18% vs. -36 ± 21%, p = 0.03), which treatment with rtPA⁵ or TAFI-I alone did not. On the other hand, combined treatment with tPA⁵ + TAFI-I showed only a trend toward lesion regression (-49 ± 26%), similarly to treatment with tPA¹⁰, but not significantly different from saline (p = 0.46). Nine animals showed microhemorrhage on T2-WI at H24. These animals were evenly distributed between groups. Conclusions: The present study showed that the combination of TAFI-I with a suboptimal dose of rtPA is not as effective as the standard dose of rtPA, while TAFI inhibition alone is not effective at all. The thromboembolic model is of particular interest in assessing rtPA association to improve thrombolysis, especially when coupled with longitudinal MRI assessment.

Simultaneous bilateral magnetic resonance angiography to evaluate thoracic outlet syndrome.

This paper presents a new magnetic resonance angiography (MRA) protocol for the evaluation of thoracic outlet syndrome (TOS) that allows for a separate assessment of veins and arteries while using a single, simultaneous and bilateral (SB-MRA) single contrast injection, valid for both abduction and adduction acquisitions. From 2009 to 2013 we performed 38 MRA studies for clinically suspected TOS (13 M, 25 F; mean age, 35.9years; σ=11.13). Twin peripheral 20G intravenous catheters were placed in a cubital vein in both arms and connected to a single power injector by two lines joined with a connector. A 3T MR system with a wide gantry was used. Two groups of four radiologists assessed all the images. Group A judged the full examinations, Group B had only the late acquisitions. Differences were evaluated using the Chi square test. TOS was confirmed only after integration with the clinical history. Seventeen (45%) patients were diagnosed with predominant venous TOS (VTOS), nine (24%) with predominant arterial TOS (ATOS) and 12 (32%) had an indeterminate or nonvascular condition. Group A radiologists identified significantly more VTOS than group B (p=0.049). Interobserver agreement was very high. SB-MRA is a safe and reliable protocol for the study of TOS. It provides a supplementary early acquisition that allows for separate assessment of veins and arteries, permits the investigation of the collateral venous flow with a single injection of contrast material and provides a higher diagnostic power for VTOS. SB-MRA is helpful for the diagnosis of TOS of vascular origin.

O7.08 * ONE-STOP SHOPPING IN BRAIN TUMOR IMAGING: INITIAL EXPERIENCE WITH PET/MR FOR SIMULTANEOUS EVALUATION OF TUMOR METABOLISM, STRUCTURE AND BLOOD VOLUME USING [18F]-FLUOR-ETHYL-THYROSINE PET AND DSC-MRI

AIM: Assessment of amino acid transport using PET tracers such as [18F]-fluor-ethyl-thyrosine (FET) is a valuable supplement to routine contrast enhanced structural MRI in the initial and follow up evaluations of patients with brain tumors. MRI blood volume (BV) imaging using dynamic susceptibility contrast (DSC) has also been shown to give important information about tumor angiogenesis. The aim of the study was to investigate the feasibility of simultaneous imaging of structural MRI, angiogenic activity (BV DSC), and metabolic activity (FET) in a short single session using an integrated PET/MRI scanner. METHODS AND MATERIALS: Twenty-five scans were obtained in 22 referred brain tumor patients. A 20 min static simultaneous PET/MRI (Siemens mMR) acquisition 20 min. p.i. of 200 MBq FET was performed. The MRI protocol included axial FLAIR and post-contrast T1 MPRAGE. For BV imaging the contrast agent (0.1-0.2 ml/kg, Gadovist 1 mmol/ml) was administered using a power injector and BV maps were calculated using dedicated software. Metabolically active tumor volume (FET-vol) was defined in tissue as activity > 1.6 x background activity (B), and metabolic activity, Tmax/B, as maximal tumor activity/B. A low-dose CT scan was obtained for attenuation correction. RESULTS: The PET/MRI scans were well-accepted by patients. Fourteen had high grade glioma (glioblastoma n = 9, oligodendroglioma III n = 4, astrocytoma III n = 1), 7 patients had low grade glioma (ganglioglioma =1, brain stem glioma n = 1, astrocytoma II n = 1, pontine glioma, oligodendroglioma n = 2, unspecified n = 1) and one patients has brain metastasis (malignant melanoma). Five patients had been exposed to anti-angiogenetic chemotherapy (Bevacizumab + irinotecan). Median tumor volume was 1.6 ml (range 0-138 ml). Areas with visually increased BV were observed in 15 of 18 scans with metabolically active tumor tissue. Scans with increased BV had significantly larger median FET-vol (4.1 ml vs 0 ml, p < 0.0005) and median Tmax/B (2.5 vs 1.4, p < 0.005) compared to those with without increased BV. Excluding scans without metabolically active tumor tissue, neither FET-vol nor Tmax/B was different. There was a high variability in the regional signals observed using FLAIR, FET PET, BV, and post-contrast T1, and poor spatial congruence between FET and BV. The fraction of scans with and without increased BV was not related to tumor grade or exposure to Bevacizumab. CONCLUSION: In the clinical management of brain tumors a simultaneous and comprehensive evaluation of structure, metabolism and blood volume is feasible in a short single session FET PET/MRI DSC scan yielding complementary high quality information. This modality may provide valuable insight into tumor biology and increase the overall diagnostic quality, decrease clinical decision time, and increase acceptance of PET imaging with patients and treating clinicians in clinical management and in trials.

Comparison of patient comfort between iodixanol and iopamidol in contrast-enhanced computed tomography of the abdomen and pelvis: a randomized trial

Previous clinical studies have shown that iso-osmolar iodixanol (Visipaque®) causes less patient discomfort than low-osmolar contrast media (LOCM) when administered via intra-arterial injection. No data are available comparing these agents for patient discomfort when administered intravenously (i.v.) using power injectors. To compare the frequency and intensity of patient discomfort between iodixanol and iopamidol (Isovue®) administered i.v. using a power injector in contrast-enhanced computed tomography (CECT) of the abdomen and pelvis. This was a prospective, randomized, double-blind, multicenter study of iodixanol 320 mg I/mL or iopamidol 370 mg I/mL on patient discomfort. The presence of discomfort (heat, pain, coldness) and intensity was verbally rated by patients on a 0-10 scale and converted into four categories (0, none; 1-3, mild; 4-7, moderate; 8-10, severe). Image quality was evaluated. Of the 299 evaluable patients enrolled at nine centers, 151 received iodixanol and 148 received iopamidol. The average age was 58 years. Iodixanol patients experienced significantly less moderate/severe discomfort (35.1% vs. 67.3%; P < 0.0001) or heat (29.8% vs. 63.9%; P < 0.0001), and severe discomfort (2.6% vs. 16.3%; P = 0.0004) or heat (2.6% vs. 15%; P = 0.0008), but three times more no discomfort (21.2% vs. 7.5%; P = 0.0008) than iopamidol patients. Excellent image quality was in 95.4% of iodixanol vs. 89.9% of iopamidol patients (P = 0.0508). Overall, adverse event (AE) rate excluding patient discomfort was 19.9% in the iodixanol group and 14.9% in the iopamidol group (P = 0.2870), but contrast-related AEs were comparable: 11.3% vs. 10.1% (P = 0.8522). Delayed skin reactions occurred in 2.6% of patients in the iodixanol group and in no patient in the iopamidol group (P = 0.1226). Patients receiving iodixanol had significantly lower moderate-to-severe or severe discomfort than patients receiving iopamidol, with heat being the major contributor. Iodixanol use trended towards better image quality but the difference was not statistically significant. No significant differences in incidences of overall or contrast-related AEs or delayed skin reactions were seen between the two groups. These data support that CM osmolality may be a key determinant of patient discomfort.

MO‐G‐18C‐02: Flow Quantification Quality Assurance for Multiple MR Scanners Using Power Injector

Purpose:To evaluate a flow quantification QA method on multiple MR scanners with different magnetic field strength from different manufacturer.Methods:Our previous study proposed a low‐cost, reliable and convenient MRI flow quantification QA method based on a simple and compact flow contrast phantom and a power injector. Five different MR scanners (Siemens MAGNETOM Espree 1.5T, Aera 1.5T and Skyra 3T; GE Optima MR450w 1.5T and Discovery MR750w 3T) were used to test the reproducibility and sensitivity of the QA method. Flow phantom phase contrast images were acquired at magnetic field isocenter for all the MR scanners. Eight repeated acquisitions and measurements were performed on each scanner. In addition, off‐center effects were tested on Siemens Espree and two GE scanners.Results:The positive flow rates measured at isocenter of five MR scanners range from +1.84± 0.01 mL/s to +2.01± 0.02 mL/s, within 8% difference from the 2mL/s flow rate provided by the power injector. The negative flow rate measured at isocenter range from −1.89± 0.01 mL/s to ‐2.14± 0.03 mL/s, within 7% difference from 2mL/s flow rate. Flow rate measures were most affected by off‐center effect when the flow phantom was shifted 12 cm transversely and 12 cm longitudinally from the isocenter. For GE Optima scanner, positive flow of +1.53± 0.01 mL/s was measured, which is 24.5% difference from power injector flow rate. For GE Discovery scanner, negative flow of −2.68± 0.02 mL/s was measured, which is 34% difference from 2mL/s flow rate.Conclusion:This QA method was sensitive enough to detect flow quantification difference between scanners. Flow quantification errors at locations away from magnetic field isocenter due to the worse gradient fidelity can be detected by our flow quantification QA method. In conclusion, flow phantom coupled with power injector is presented to be a widely available, consistent and low cost flow quantification method.

Contrast medium application in pediatric high-pitch cardiovascular CT angiography: Manual or power injection?

BackgroundDual-source CT offers accurate depiction of cardiac structures in children with congenital heart disease. For cardiac CT, optimal enhancement of the cardiovascular structures is essential. There is considerable controversy about the administration of contrast medium (CM) in infants and small children, with either a power injector or a manual (hand) injection. ObjectiveThe aim of this study was to compare image quality with power injection of CM (study group) and manual injection (control group). MethodsThirty-four patients (study group, 6.8 ± 9.6 months and control group, 4.6 ± 8.9 months, nonrandomized) underwent dual-source CT angiography of the chest using a prospective electrocardiography-triggered high-pitch spiral mode (pitch, 3.4; 80 kV). In the study group (17 patients), a power injector was used, and in the control group (17 patients, historical group), manual CM injection had been performed. To assess image quality, both subjective and objective parameters were evaluated independently by 2 experienced radiologists. ResultsSubjective overall image quality, signal-to-noise ratio, and contrast-to-noise ratio were significantly higher using power injection compared with manual injection (P < .05). However, depiction of cardiovascular structures did not differ significantly between both groups in all evaluated regions except the superior vena cava and the coronary arteries. ConclusionIn infants and small children with congenital heart disease, both manual and power injector protocols allowed for diagnostic imaging of cardiac and extracardiac structures. However, image quality and vascular attenuation were superior using a power injector.

Post-marketing surveillance study with iodixanol in 20 185 Chinese patients from routine clinical practices

Objective:To determine the incidence of immediate and delayed adverse drug reactions (ADRs), and to assess patient discomfort following administration of iodixanol during imaging examinations in routine clinical practice.Methods:A total of 20 185 patients across 95 clinical centres were enrolled in a prospective post-marketing surveillance registry with iodixanol. Patients were monitored for occurrence of ADRs immediately following iodixanol administration and for up to 7 days after administration.Results:The overall rate of ADRs was 1.52%, of which 0.58% was immediate and 0.97% was delayed onset. Two patients had non-fatal serious ADRs (0.01%). The ADRs were significantly more common in patients who underwent contrast-enhanced CT/coronary CT angiography vs others (p < 0.001), in those receiving pre-heated iodixanol vs non-heating (p < 0.001), in those aged 70 years or younger (p < 0.001), in those in whom a power injector was used for contrast delivery (p < 0.001) and in those with a history of an allergic reaction to contrast (p = 0.024). Multivariate analysis showed that female gender, intravenous route of contrast injection, body weight ≥80 kg, age less than 65 years, contrast flow rate ≥4 ml s−1 and prior reaction to iodinated contrast medium were all significant and independent contributors to ADRs. Pre-treatment contrast volume and history of cardiac disease, gout, hypertension, diabetes mellitus or asthma did not affect the rate of ADRs. Discomfort was generally mild, with 94.8% of patients reporting a composite score of 0–3.Conclusion:The safety of iodixanol in routine clinical practice was shown to be similar to the published safety profiles of other non-ionic iodinated contrast agents. Patient discomfort during administration was mild or absent in most patients.Advances in knowledge:The major strength of this study is that it included 20 185 patients enrolled in various types of imaging examinations. The safety profile of iodixanol was comparable to previously published work.

Unsupervised free-breathing 3D imaging of morphology, function and flow in congenital heart disease

Methods Five patients with CHD were included in this pilot study. The MR studies were performed on a Philips Acheiva 1.5T magnet using a multielement phased array coil with the following sequences in this order: 1. Free-breathing, respiratory synchronized [1], time-resolved MRA following injection of 0.03 mmol/kg of Gadofosveset, and injection rate 2-4cc/second using a power injector. Duration: < 1 minute 2. Free breathing equilibrium phase MRA, acquired voxel size 0.8 × 0.8 × 1.6 mm, 2 NEX. Duration: 2.5-4 minutes 3. Free breathing 3D cine SSFP with respiratory triggering (TR/TE/flip angle: 3/1.5/60; acquired voxel size: 1.5-1.9 × 1.5-2.1 × 7-8 mm3; SENSE acceleration factor: 1.5-2 × 1.5-2; temporal resolution: 30-45 ms). Duration: 4.5-7 minutes 4. Free breathing sagittal 4D phase contrast (PC) imaging with respiratory navigator (18-26 phases/cardiac cycle, Venc 150 cm/sec, spatial resolution 1.6-2.8 mm3.) Duration: 6-12 minutes 5. Free breathing 3D SSFP with respiratory navigator. (acquired voxel size 1 × 1 × 2 mm3) Duration: 5-7 minutes Comparative data was obtained using conventional 2D cine respiratory triggered SSFP sequences (2) in the VLA, 4 chamber and short axis planes, and 2D PC imaging. Data Analysis: Image quality assessment and quantitative volumetric and flow analysis was performed by a single blinded user. MRA images were graded using a semi-quantitative scale from 1-5 for relevant imaging targets in CHD [1], with 1: excellent, no limitations, and 5: non-diagnostic. The clinical scoring system for 2D and 3D cine SSFP was based on blood-myocardial contrast, endocardial edge definition and inter-slice alignment[2]. Paired t-test analysis was performed on LV and RV volumes.

Syringeless power injector versus dual-syringe power injector: economic evaluation of user performance, the impact on contrast enhanced computed tomography (CECT) workflow exams, and hospital costs

ObjectiveThe utilization of diagnostic imaging has substantially increased over the past decade in Europe and North America and continues to grow worldwide. The purpose of this study was to develop an economic evaluation of a syringeless power injector (PI) versus a dual-syringe PI for contrast enhanced computed tomography (CECT) in a hospital setting.Materials and methodsPatients (n=2379) were enrolled at the Legnano Hospital between November 2012 and January 2013. They had been referred to the hospital for a CECT analysis and were randomized into two groups. The first group was examined with a 256-MDCT (MultiDetector Computed Tomography) scanner using a syringeless power injector, while the other group was examined with a 64-MDCT scanner using a dual-syringe. Data on the operators’ time required in the patient analysis steps as well as on the quantity of consumable materials used were collected. The radiologic technologists’ satisfaction with the use of the PIs was rated on a 10-point scale. A budget impact analysis and sensitivity analysis were performed under the base-case scenario.ResultsA total of 1,040 patients were examined using the syringeless system, and 1,339 with the dual-syringe system; the CECT examination quality was comparable for both PI systems. Equipment preparation time and releasing time per examination for syringeless PIs versus dual-syringe PIs were 100±30 versus 180±30 seconds and 90±30 and 140±20 seconds, respectively. On average, 10±3 mL of contrast media (CM) wastage per examination was observed with the dual-syringe PI and 0±1 mL with the syringeless PI. Technologists had higher satisfaction with the syringeless PI than with the dual-syringe system (8.8 versus 8.0). The syringeless PI allows a saving of about €6.18 per patient, both due to the lower cost of the devices and to the better performance of the syringeless system. The univariate sensitivity analysis carried out on the base-case results within the standard deviation range confirmed the saving generated by using the syringeless device, with saving values between €5.40 and €6.20 per patient.ConclusionThe syringeless PI was found to be more user-friendly and efficient, minimizing contrast wastage and providing similar contrast enhancement quality compared to the dual-syringe injector, with comparable CECT examination quality.

Intravascular Enhancement With Identical Iodine Delivery Rate Using Different Iodine Contrast Media in a Circulation Phantom

Both iodine delivery rate (IDR) and iodine concentration are decisive factors for vascular enhancement in computed tomographic angiography. It is unclear, however, whether the use of high-iodine concentration contrast media is beneficial to lower iodine concentrations when IDR is kept identical. This study evaluates the effect of using different iodine concentrations on intravascular attenuation in a circulation phantom while maintaining a constant IDR. A circulation phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used (heart rate, 60 beats per minute; stroke volume, 60 mL; blood pressure, 120/80 mm Hg). Maintaining a constant IDR (2.0 g/s) and a constant total iodine load (20 g), prewarmed (37°C) contrast media with differing iodine concentrations (240-400 mg/mL) were injected into the phantom using a double-headed power injector. Serial computed tomographic scans at the level of the ascending aorta (AA), the descending aorta (DA), and the left main coronary artery (LM) were obtained. Total amount of contrast volume (milliliters), iodine delivery (grams of iodine), peak flow rate (milliliter per second), and intravascular pressure (pounds per square inch) were monitored using a dedicated data acquisition program. Attenuation values in the AA, the DA, and the LM were constantly measured (Hounsfield unit [HU]). In addition, time-enhancement curves, aortic peak enhancement, and time to peak were determined. All contrast injection protocols resulted in similar attenuation values: the AA (516 [11] to 531 [37] HU), the DA (514 [17] to 531 [32] HU), and the LM (490 [10] to 507 [17] HU). No significant differences were found between the AA, the DA, and the LM for either peak enhancement (all P > 0.05) or mean time to peak (AA, 19.4 [0.58] to 20.1 [1.05] seconds; DA, 21.1 [1.0] to 21.4 [1.15] seconds; LM, 19.8 [0.58] to 20.1 [1.05] seconds). This phantom study demonstrates that constant injection parameters (IDR, overall iodine load) lead to robust enhancement patterns, regardless of the contrast material used. Higher iodine concentration itself does not lead to higher attenuation levels. These results may stimulate a shift in paradigm toward clinical usage of contrast media with lower iodine concentrations (eg, 240 mg iodine/mL) in individual tailored contrast protocols. The use of low-iodine concentration contrast media is desirable because of the lower viscosity and the resulting lower injection pressure.

Perfusion Defects Detected After Liver Transplantation on Multidetector Computerized Tomography: Short- and Long-Term Follow-up

BackgroundPerfusion defects are sometimes found during the follow-up computerized tomography (CT) after liver transplantation (OLT). This study sought to determine the short- and long-term outcomes of perfusion defects observed after OLT with the use of multidetector CT. MethodsFrom February 4, 2004, to December 8, 2011, a total 46 LTs were performed in our hospital owing to end-stage liver cirrhosis (n = 43), liver cirrhosis with hepatocellular carcinoma (HCC; n = 1), combined HCC with cholangiocellular carcinoma (CCC; n = 1), or hepatic failure from acute hepatitis A (n = 1). The transplanted livers were procured from cadaveric (n = 24) or living related donors (n = 22). The average age of the recipient was 53.3 ± 10.4 years. The male-female ratio was 30:16. Postoperative multidetector CT was performed with a dynamic sequence in 203 examinations and with a portal phase in 46 examinations. The contrast media was Radisense. The rate of injection of 120 mL was 3 mL/s with a power injector; the iodine concentration was 300 or 370 mg/dL. Follow-up ranged from 3 months 3 days to 7 years 363 days. We classified perfusion defects as chronic segmental or subsegmental benign ischemia, transient focal perfusion defects, benign subcapsular ischemia, or fatal whole liver perfusion defects. ResultsThere were 3 cases of chronic segmental or subsegmental benign ischemia, 8 focal transient perfusion defects, 1 benign subcapsular ischemia, and 4 fatal whole liver perfusion defects. Except the fatal cases, all other perfusion defects occurred in the courses of benign conditions without resection or reoperation. ConclusionsMost perfusion defects were benign and uneventful, requiring no treatment, with the exception of fatal whole liver perfusion defects, which resulted in death after detection.

Power injector associated iatrogenic air embolism to the right heart

Air embolism is the entry of air into the vascular system and is usually associated with surgeries, trauma and central lines.1 A patient presented to the clinic with new onset...

Effectiveness of the new injection program ‘saline test injection mode’ for use power injector in pediatric contrast CT

To improve the safety of the use of a power injector for pediatric contrast CT, we newly developed a saline test injection mode for a power injector and investigated its usefulness. We used an injection route and investigated the relationship of the injection pressure to the injection rate of saline and the contrast medium. From this relationship, we investigated it was possible to estimate the change of pressure injection of contrast medium from the pressure change of saline injection. The correlation between the saline test injection pressure and the contrast medium injection pressure was investigated in 64 clinical cases. The detection rate of side effects from the saline test injection was investigated in 473 patients. Regarding the correlation between the injection rate and pressure for both saline and contrast, the pressure rose as the rate increased. The contrast medium injection pressure could be estimated from the correlation observed with saline. The clinical data were obtained had a relationship similar to that with phantom data. The detection rate of side effects from the saline test injection was 4.4% in the clinical cases. In these cases, examinations were completed by re-establishing an injection route or administering hypnotics. Our results suggest that contrast medium pressure can be estimated from a saline test injection, thus aiding in prediction of the risk of injection abnormality. Reactions to injections could be observed in the present study, facilitating the prevention of examination failure. Countermeasures can be taken against the cause of the reaction, and the examination can be performed after confirming the absence of a reaction to injection. Therefore, a saline test injection may be useful in pediatric contrast CT.

Artifacts caused by insufficient contrast medium filling during C-arm cone-beam CT scans: a phantom study

We investigated artifacts due to late-arriving contrast medium (CM) during C-arm cone-beam computed tomography. We scanned a phantom filled with water or with 100, 50, or 5% v/v concentrations of CM and then virtually produced CM-delayed projection data by partially replacing the projection images. Artifacts as a function of concentration, percentage of filling time, and size and position of the filling area were assessed. In addition, we used an automatic power injector with different injection delays to inject CM during the scans. A decrease in filling times caused by a lag in CM arrival during the scan resulted in a decrease in pixel values, distortion of the filling area, and appearance of streak artifacts. Even a delay of approximately 20% in CM arrival in the total scan time resulted in obvious distortion of the filling area. The distortion and streak artifacts tended to worsen at higher CM concentrations. Use of a minimum CM concentration based on the purpose of the examination and constant filling at the target region are effective for avoiding these artifacts.

WE‐C‐116‐09: A Novel Flow Quantification Quality Assurance Method Using Power Injector

Purpose: To develop a practical flow quantification quality assurance method based on a simple and compact flow phantom driven by a power injector. Methods: A flow phantom was made using acrylic with U‐shaped tubes built inside the chamber and immersed in stationary saline. A MR power injector equipped with the MR scanner was used to inject up to 110 mL of saline through the tube with 4.76 mm inner diameter at a precise rate of 2.00+/−0.01 mL/s. 2D phase contrast flow quantification was performed with a single imaging slice of 10mm perpendicular to the straight sections of the U‐shape tube on two different models of 1.5T MR scanners (Siemens Espree and Aera). Flow rates in two opposite directions were measured from phase contrast images using Siemens ARGUS software. Eight repeat measurements were performed for each scanner. Results: The flow rates measured on the Espree scanner were +2.15+/−0.06 mL/s with 7.45% difference from the 2mL/s flow rate provided by the power injector and −2.17+/−0.03mL/s with 8.7% difference. On the Aera scanner, the flow rates were +1.90+/−0.03mL/s with 4.8% difference from the 2mL/s produced by the power injector and −1.99+/−0.02mL/s with 0.6% difference. The measured flow rates were different from the true flow rate for both scanners and the error were different between scanners. Conclusion: Our proposed method of quality assurance using a simple flow phantom driven by a power injector was able to detect the errors in flow quantification for both scanner as well as the difference between two scanners. Such method can be implemented on many clinical MR scanners already equipped with a power injector.

Abstract No. 283 - Bench top model for comparing flow rate measurements from a thermodilution catheter to a novel software based method of flow quantification using digital subtraction angiography

Purpose Intra-access blood flow rates are used for monitoring dialysis access function. We hypothesize that flow can be calculated from Digital Subtraction Angiograms (DSA) during fistulography. The purpose of this study is to compare DSA-based flow quantification algorithms with thermodilution catheters. Materials and Methods Using a flow model with a 37 °C water bath and 3/8′ silicone tubing similar to prior studies (1), thermodilution and 8 DSA flow algorithms were used at rates from 400-1200 mL/min. Power injectors were used for room temperature saline and contrast injections. Thermodilution was repeated 6 times and DSA was repeated 3 times at 3, 6, 7.5, and 10 frames per second (FPS). Actual flow rate was estimated by measuring the volume displaced in 1 minute. Mean and standard deviation (SD) of each algorithm was determined and the algorithm with the closest flow to estimated flow and smallest standard deviation was correlated with the thermodilution catheter measurements. Repeatability coefficient (RC) for DSA and thermodilution methods was estimated for each flow rate and the limits of agreement (LOA) were assessed between the 2 methods at each frame rate. Results Cross Correlation (CC) had the smallest SD and closest values to actual flow. The mean difference between CC and thermodiluton was 44.2±75; 144.7±37; 230.6±52; and 232.6±25 mL/min at 3, 6, 7.5, and 10 FPS. The SD of all other algorithms at all frame rates were >100 mL/min. RC increased from 149.2 to 709.7 with increasing flow rate for CC and from 46.9 to 191.2 for thermodilution. Higher RC indicates more variability in measurements. LOA increased with increasing frame rate from 52±209 to 232±91 mL/min. Conclusion Given that flow rates from the DSA method were consistently higher and more variable than thermodilution values, further refinement of the software algorithms is needed. Reproducibility and accuracy need to be improved prior to clinical use of this method for flow estimation. Reference 1. Heerwagen ST, Lonn L, Schroeder TV, Ladefoged SD, Hansen MA. Catheter-based flow measurements in hemodialysis fistulas - bench testing and clinical performance. J Vasc Access. 2012 Jan-Mar;13(1):45-50. doi: 10.5301/JVA.2011.8443. PubMed PMID: 21725955.

Dislodgement of a Power-Injectable Peripherally Inserted Central Catheter After Power Injection: A Case Report

A 63-year-old Malay woman had a 6-French dual-lumen power-injectable peripherally inserted central catheter (PICC) inserted and subsequently underwent a contrast-enhanced computed tomography scan with intravenous contrast medium administered via the PICC. After the scan, the tip of the PICC was noted to have displaced from its original position and lodged in 1 of the small branches of the right subclavian vein. This phenomenon was then demonstrated in real time under fluoroscopy during the process of repositioning the PICC tip. Although power-injectable PICCs are designed for use with power injectors, tip displacement can and does happen. A computed tomography scout view of the chest may be necessary after each use of power injectors to confirm that the PICC tip remains in a satisfactory position.

Bracco Diagnostics Inc. (BDI) is recalling nine lots of Isovue [iopamidol] pre-filled power injector syringes,

Bracco Diagnostics Inc. (BDI) is recalling nine lots of Isovue [iopamidol] pre-filled power injector syringes,

Bracco Diagnostics Inc. (BDI) is recalling nine lots of Isovue [iopamidol] pre-filled power injector syringes,

Bracco Diagnostics Inc. (BDI) is recalling nine lots of Isovue [iopamidol] pre-filled power injector syringes,