Accuracy and Repeatability of Automated Injector Versus

ORIGINAL ARTICLE

Accuracy and Repeatability of Automated Injector Versus ManualAdministration of an MRI Contrast AgentmdashResults of a

Laboratory Study

Jan Endrikat MD PhDdagger Ron Barbati BSDagger Marcella Scarpa PhDsect

Gregor Jost PhD|| and Arthur E (Ned) Uber III PhDpara

d

injection procedures particularly the flow rate should be well define

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Objective The aim of this study was to compare flow rates over time and the dviations from the target flow rate of a magnetic resonance imaging contrast ageachieved by an automated injector versus manual injectionMaterials and Methods In this laboratory study the magnetic resonancontrast agent gadobutrol was repeatedly injected by an injector and by 10 eperienced technologists Six scenarios with 2 different target flow rates (1 an5 mLs) 2 different contrast volumes (10 and 20 mL) and 2 different intravnous (IV) catheters (22 gauge and 20 gauge) were tested The flow rates ovtime were recorded The target variable was the average absolute deviatioand average absolute percentage deviation from the target flow rateResults The flow rates over time achieved by an injector were almost identicSlight deviations from the target flow rate occurred during ramp-up and ramdown only Those of manual injection showed high variability over the whocourse of the injection In the 1 mLs scenarios the injector deviated frothe target flow rate by 006 mLs or less (le6) and in the 5 mLs scenariby 102 mLs or less (lt20) For the manual injections at the same flow ratethese figures were 035 mLs or less (le35) and 31 mLs or less (le62)Conclusions Injector administration of a magnetic resonance contrast ageminimally deviated from the target flow rate whereas manual injection variwidely Injector administration is more accurate and repeatable

Key Words injector administration manual administration target flow ratesMR contrast agents

(Invest Radiol 201800 00ndash00)

A ll contrast-enhanced magnetic resonance imaging (MRI) procdures should include accurate and repeatable contrast agent admi

istration An accurate flow rate is most important for first-pass imaginsuch asMR angiography (MRA) and time-resolved imaging such as hpatic arterial phase measurements These procedures require a precisynchronization of contrast agent arrival in the target region and thMRI acquisition This is especially relevant for low-dose contrast age

Received for publication May 12 2017 and accepted for publication after revisionJune 29 2017

From the Bayer AG Radiology RampD Berlin daggerDepartment of Gynecology ObstetricsandReproductiveMedicine UniversityMedical School of Saarland HomburgSaarGermany DaggerBayer HealthCare LLC MRI Medical and Clinical Affairs RadiologyIndianola IA sectBayer (South East Asia) Pte Ltd Singapore ||Bayer AG MRamp CTContrast Media Research Berlin Germany and paraBayer HealthCare LLC Radiol-ogy Device Research and Early Development Indianola IA

Conflict of interest and source of funding All authors are employees of Bayer AG Thestudy was funded by Bayer AG

Correspondence to Jan Endrikat MD PhD Bayer AG Radiology RampD Muumlllerstr178 13353 Berlin Germany E-mail janendrikatbayercom

Copyright copy 2017 The Author(s) Published by Wolters Kluwer Health Inc This is anopen-access article distributed under the terms of the Creative CommonsAttribution-Non Commercial-No Derivatives License 40 (CCBY-NC-ND)where it is permissible to download and share the work provided it is properlycited The work cannot be changed in any way or used commercially without per-mission from the journal

ISSN 0020-9996180000ndash0000DOI 101097RLI0000000000000403

Investigative Radiology bull Volume 00 Number 00 Month 2018

and standardizedMagnetic resonance contrast agents can be injected manually

by using an automated injection system Depending on the patiencharacteristics the indication for the imaging and the contrast agendifferent contrast volumes are to be injected at different injection ratusing needles or catheters with different diameters1 To achieve reprducible high-quality imaging data accurate and reproducible florates and a short interval between contrast injection and saline chasshould be a goal23 To the best of our knowledge a thorough heato-head comparison of injection parameters of injector versus manuadministration of an MRI contrast agent has not been performed so fa

The primary goal of this study was to record flow rates of aMRI contrast agent achieved by use of an automated injection systeversus manual administration over time and to calculate the deviatiofrom the target flow rate

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MATERIALS AND METHODS

Study SetupThe experimental setup is shown on Figure 1 It allowed me

surement of the flow rate and the total volume injected over time fboth contrast and saline Data for both parameters were recorded eletronically Contrast and saline were injected through different lineconsisting of catheters and a swabable valve transfer set mimickinthe vein into separate bags placed on a scale so they could be recyclefor repeated use without contamination or dilution The scale wprotected from external influences by a built-in wind shield

Injector and Manual AdministrationThe setup for injector and manual injection was identical usin

the same 2 separated fluid paths for contrast and saline Either injector hand syringes were connected to the stopcocks (Fig 1)

Injector administration was performed with the injection sytem MRXperion (Bayer AG) The maximum pressure limit was sto the default of 325 psi (2240 kPa) The flow rates were set to be thof the injection targets for the test series 5 mLs and 1 mLs respetively The injector was operated by an experienced Bayer scientistechnician (NU)

Manual injection was performed by 10 technologists (andashj) wiat least 5 years of experience in clinical practice Each technologist peformed a total of 13manual injections On each test day 2 or 3 technoogists performed those 13 injections The first manual injection wperformed as a training exercise to familiarize them with the test setuThe technologists were asked to inject as they normally do in their cliical routine Then they did 12 injections each 2 for each of 6 scenariwith different IV catheters different contrast volumes and differeinjection speeds (see below) Mimicking their daily routine 8 tecnologists exchanged the contrast syringe with a saline syringe to aminister the flush and 2 used the stopcock to switch from contrast

wwwinvestigativeradiologycom 1

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FIGURE 1 Experimental setup For hand syringe tests the two stopcocks were mounted one on top of the other to simulate the turning orinsertion motion that the technologists use to flush To mount on the injector the two stopcocks were separated and mounted on the correspondinginjector syringes

Endrikat et al Investigative Radiology bull Volume 00 Number 00 Month 2018

saline All were blinded to their injection performance to avoid a learing effect In addition the staff working with the technologists did nsee the flow rate over time curve displayed on the measurement systecontrol panel during the test to avoid accidental feedback by body laguage To avoid fatigue injections were performed on a rotating basiA technologist performed a given injection followed by the other members of that group so that no technologist performed 2 consecutive maual injections Each participant on a given day performed a total12 manual injections 2 per scenario for the 6 scenarios On the daywhere there were just 2 technologists one of the Bayer observetook a turn so that the rest time was approximately the same for atest groups

Six scenarios with 2 different IV catheters (22 gauge an20 gauge) 2 different contrast volumes (10 and 20 mL) and 2 differeinjection speeds (1 and 5 mLs) were tested The injector and each tecnologist performed each scenario twice (Table 1)

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Target ParametersFor all 6 scenarios the flow rates over time were continuous

recorded for injector and manual administration The primary targvariable was defined as the average absolute and average absolupercentage deviation from the target flow rate The deviations weadded without considering the direction of deviation Thus the terabsolute refers to the fact that deviations in flow rates above (postive) and below (negative) the target were summed as to their abslute numerical deviation without regard to the plusmn sign so positive annegative deviations did not average out

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TABLE 1 Test Scenarios for Injector and Manual Administrations

Scenario

TargetFlowRate

CMVolume

IVGauge

MRXperionNo Tests

10 Technologists(andashj) No Tests

1 5 mLs 10 mL 22 2 202 5 mLs 20 mL 22 2 203 1 mLs 10 mL 20 2 194 1 mLs 20 mL 20 2 205 5 mLs 20 mL 20 2 206 5 mLs 10 mL 20 2 20

Σ12 Σ119

2 wwwinvestigativeradiologycom

StatisticsBecause this was a pilot study no statistical hypothesis could b

stated All results are reported descriptively

MaterialsThis study used the following materials injector MRXperio

(VV1010 with a valid calibration sticker) contrast 1 M gadobutr(Gadovist Bayer AG Leverkusen Germany)45 computer LenovG40 equipped with Windows XP (National Instruments Labvie2013 service pack 1 M62x65157I) program Mettler Balance anflow meter (ver04_johnvi saved on May 24 2013 1218 PM) NcDAQ-9147 support frame NI 9215 input module for flow metetransonic flow meters ME2PXl1019 Medrad Calibration 13405ndashand ME2PXl1018 Medrad Calibration 13405ndash2 (Rev Filter on 40 Hmeasuring 20 data points per second [1 data point each 005 secondscale Mettler Toledo PR 2003 Delta Range (control number 1334RevmdashPR2003 DR SNR 1125360581 TDNR 26473122ndash0 last cabrated December 2014) Stopcock 565311 IV catheters (20 gaugBD Ref 381134 and 22 gauge BD Ref 381123) SVTS (swabable valvtransfer set) Halkey Roberts swabable valve 245204024 13-in lengof MR 65115 VS tubing (0075-in ID 0125-in OD)

RESULTSThe flow rates over time for all 6 scenarios are shown in FigureWhile the flow rates over time of the 2 injector administrations

each scenario were almost identical those for the intraindividual and iterindividual manual injections varied widely

Contrast injections were followed by a saline flush The time iterval between the administration of contrast and saline was clearly viible as a trough in the flow rate curves between these 2 injection phaseThis was best shown in the 5 mLs scenarios (scenarios 1 2 5 an6) performed by the injector

The target flow rate of 5 mLs in scenarios 1 2 5 and 6 wquickly reached by the injector with some slight deviation durinramp-up and ramp-down whereas the flow rate of 5 mLs was reacheonly in rare cases by manual injection The target flow rate of 1 mL(scenarios 3 and 4) was precisely reached by the injector with almono gap between the contrast and saline phase whereas the flow ratover time for manual injections varied up to 31 mLs

The total injection duration depends on the contrast volume anthe injection speed In the 1 mLs scenarios (scenarios 3 and 4) the ijector precisely injected the contrast within 10 and 20 seconds respetively In the 5 mLs scenarios the injection duration with the inject

copy 2017 Wolters Kluwer Health Inc All rights reserved

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FIGURE 2 Injection profiles of 2 injector administrations (arrows) in comparison to a series of manual administrations by multiple technologists The dipindicates the switch from contrast to saline

Investigative Radiology bull Volume 00 Number 00 Month 2018 Injector vs Manual Administration of a GBCA

was slightly longer as calculated to achieve the total flow due to the cotrolled ramp-up and ramp-down Manual injections always took signiicantly longer than injector administrations

There was a remarkable difference between the hand injectionwith the smaller 22-gauge catheter and the larger 20-gauge cathet(compare scenario 1 with 6 and 2 with 5 see Fig 2) This was not oserved for the injector administrations

Figure 3 and Table 2 show the average absolute and average asolute percentage deviations from the target flow rate for all 10 techncians (andashj) and the injector administrations

In the 1mLs scenarios the injector deviated from the target florate by 006 mLs or less (le6) and in the 5 mLs scenarios b102 mLs or less (lt20) For the manual injection these figures we035 mLs or less (le35) and 31 mLs or less (le62) respectivelThe flow rates of the saline flush are shown in Table 2 The applied cotrast agent volume of 10 or 20 mL does not systematically affect the acuracy of the flow rate

Two of the technologists used stopcocks for switching from cotrast to saline 8 exchanged the syringes The mean switching time fall 10 technicians varied between 1 and 6 seconds The injector injectesaline immediately after the contrast (Fig 4)

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DISCUSSIONIn this laboratory study we measured flow rates of an MRI co

trast agent and saline chaser achieved by injector versus manual admiistration over time As primary target parameters we calculated thaverage absolute deviation and average absolute percentage deviationfrom the target flow rate To the best of our knowledge a direct compaison of manual versus injector flow rates has not been published so fa


The data from this study showed that flow rates over time of theinjector-based contrast agent administrations in each scenario wealmost identical whereas those for the manual injections showewide intraindividual and interindividual variations This evidencsubstantiates the accuracy and repeatability of the injector adminitrations In particular the target flow rate of 5 mLs was consistentachieved by the injector and rarely via the manual method This mabe of clinical importance for dynamic imaging procedures to evalate perfusion (dynamic susceptibility contrast imaging and dynamcontrast-enhanced [DCE] Imaging) which require a high injectiorate for example for cardiac perfusion imaging6 or perfusion imaing in acute ischemic stroke7 Here a short compact contrast agebolus shape with a high bolus peak and consequently an increasesignal-to-noise ratio are key8

Also low injection rates such as 1 mLs are highly time-criticafor example in MRA of run-offs and liver imaging Here highly precisynchronization of contrast delivery and image acquisition is necessarThe basis for this synchronization is a well-controlled contrast ijection procedure that provides accurate and repeatable bolutiming Our data show that this is achievable with injector-baseadministration but not with manual administration which is highoperator dependent

A slight deviation from the target flow rate during injector aministrations is recorded as ramp-up and ramp-down This is causeby a programmed acceleration rate intended to limit the amount of cateter whip and turbulence in the patients vein and thus increasing thsafety of the injection for the patient9 In dynamic susceptibility contraimaging and DCEMRI studies of the brain a minimum bolus injectiorate of 3 mLs is recommended to allow compact bolus arrival in the crebral tissue10 providing the needed temporal signal intensity chang


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FIGURE 3 The measured average absolute deviations (mLs) (A and B) and average percentage deviations () (C and D) from target contrast flow rate(1 mL and 5 mL) per technician (andashj) and injector (MRXperion)


Also in cardiac perfusion imaging and for the characterization of tummicrovasculature in prostate cancer DCE is frequently used11 In clincal scenarios such as these the data from this study indicate that manuadministration may be inconsistent and thus suboptimal In additioalso at 1 mLs high accuracy and repeatability are important for example for injection protocols for MRA of run-offs and contrast-enhanceliver imaging

The average absolute deviation and average absolute percentagdeviation from the target flow is the key parameter for injection accracy We could show that the relative deviations for injector administrtions were 6 or less and less than 20 for the 1 mLs and 5 mL

TABLE 2 Average Absolute Deviation (mLs) and Average Absolute PAdministration for Contrast and Saline (20 mL) in each Scenario

Injector A

Scenario Target Flow Rate Contrast

1 5 mLs 099 plusmn 00520 plusmn 1







scenarios respectively These results are mainly caused by the ramup and ramp-down phase A safety feature in the injectors softwalimits the acceleration rate to a set value to reduce any jetting effecand vessel wall damage on ramp-up and ldquowater hammerrdquo from hdraulic inertia on the ramp-down phase For manual administratiothe deviation was more than 3-fold higher that is le35 and le62These results show that due to intraindividual and interindividuvariations accurate and repeatable injection flow rates are unlikewhen manually administering intravenous MRI contrast media

Furthermore correct total injection duration was only possibwith the injector administrations Manual injections lasted typical

ercentage Deviation () From Target Flow Rate for Injector vs Manual

Average Absolute Deviation plusmn SD (mLs)

Average Absolute Percentage Deviation plusmn SD ()

dministration Manuel Administration

Saline Contrast Saline

132 plusmn 003 31 plusmn 045 24 plusmn 03226 plusmn 1 62 plusmn 9 49 plusmn 6133 plusmn 001 30 plusmn 035 23 plusmn 04927 plusmn 0 60 plusmn 7 46 plusmn 10009 plusmn 000 035 plusmn 021 051 plusmn 0409 plusmn 0 35 plusmn 21 51 plusmn 40010 plusmn 000 033 plusmn 028 034 plusmn 03010 plusmn 0 33 plusmn 28 34 plusmn 30099 plusmn 001 24 plusmn 068 18 plusmn 05320 plusmn 0 48 plusmn 14 36 plusmn 11100 plusmn 001 22 plusmn 068 16 plusmn 05120 plusmn 0 45 plusmn 14 33 plusmn 10


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FIGURE 4 Switching time (maximum average minimum) (second)between contrast and saline injection during manual injection pertechnician (indashg) arrows indicate 2 technicians using stopcocks Plot isin order of fastest to slowest technologists


longer than calculated and required (for optimal imaging) which makestimating the peak enhancement in a certain vascular area a challengIn particular for long injection times (gt15 seconds) the recirculated cotrast agent mix with the injected contrast agent and thus contributesthe bolus profile In contrast to CT the impact on the image quality hnot yet systematically been investigated However considering the loinjection volumes in MRI the effect of recirculation might be limited

In addition the time (gap) between the end of the contrast ijection and beginning of the saline flush for all 10 technicians variebetween 1 and 6 seconds Technician ldquoirdquowas the fastest with 25 seonds by using a stopcock The switching time was independentthe technicians years of job experience The gap for the injectwas remarkably smaller Both parameters the total injection durtion as well as the gap between the 2 injection phases have an effeon the accurate timing between contrast agent injection and imagacquisition which is important for all first-pass contrast-enhanceMR techniques in particular 3D-MRA If the image acquisitioand the arterial phase are mistimed suboptimal arterial enhancemeor venous contamination may result in reduced image quality Tecnically synchronization for bolus arrival and image acquisition cabe ensured by the use of bolus tracking techniques or prior test bolumeasurement13ndash15 However the latter highly depends on repeatabinjection rates An additional source of variation can be the longgap between the 2 injection phases that is hand switching timeLonger switching times may cause inconsistent bolus spreadingpatients because some of the contrast agent bolus may be carriedownstream by themore rapid central venous flow and themore periperal segment of the bolus may be delayed The direct impact of the ijection duration and switching time on the bolus geometry (ie the bolwidth and peak height) hasmdashto the best of our knowledgemdashnot beeinvestigated yet

Although these bench tests cannot prove or demonstrate a direclinical impact in humans they clearly demonstrate the significanthigher capability of an injector-based contrast administration in termof accuracy and repeatability when compared with a manual injectioThe final goal is to show that highly accurate and repeatable injectioof the MRI contrast agent results in improved image quality ormdash


the best of all scenariosmdashin improved diagnoses and treatment planing Therefore our study program is complemented by a preclinicstudy in pigs16 and a clinical study on brain perfusion tests in ptients with brain tumors which is still running The preclinical studin 6 pigs by Jost et al16 recently confirmed that injector contraagent administration results in more standardized bolus shapes anhigher vascular contrast in MRA In addition they suggested thinjector-based contrast administration also results in more robust visalization of target vessels and hence provide potentially higher diagnotic image quality

CONCLUSIONSInjector administration of anMRI contrast agent minimally dev

ated from the target flow rate whereas manual injection varied widelInjector administration is more accurate and repeatable

REFERENCES

1 Friebe M Computed tomography and magnetic resonance imaging contramedia injectors technical feature reviewmdashwhat is really needed Med Devic(Auckl) 20169231ndash239

2 Husarik DB BashirMRWeber PW et al Contrast-enhancedmagnetic resonanangiography first-pass arterial enhancement as a function of gadolinium-chelaconcentration and the saline chaser volume and injection rate Invest Radi201247121ndash127

3 Boos M Scheffler K Haselhorst R et al Arterial first pass gadolinium-Cdynamics as a function of several intravenous saline flush and Gd volumeJ Magn Reson Imaging 200113568ndash576

4 Endrikat J Vogtlaender K Dohanish S et al Safety of gadobutrol results fromclinical phase II to IV studies and postmarketing surveillance after 29 million aplications Invest Radiol 201651537ndash543

5 Scott LJ Gadobutrol a review of its use for contrast-enhanced magnetic resnance imaging in adults and children Clin Drug Investig 201333303ndash314

6 Plein S Kozerke S Suerder D et al High spatial resolution myocardial perfusicardiacmagnetic resonance for the detection of coronary artery diseaseEur HeaJ 2008292148ndash2155

7 Keston P Murray AD Jackson A Cerebral perfusion imaging using contraenhanced MRI Clin Radiol 200358505ndash513

8 Zhang H Maki JH Prince MR 3D contrast-enhanced MR angiography J MaReson Imaging 20072513ndash25

9 Available at httpswwwradiologysolutionsbayercomstaticmediaPDFs2-3-1_Medrad_Mark_7_ArterionMedrad_Mark_7_Arterion_Brochurepd AccessJune 23 2017

10 EssigM Nguyen TB Shiroishi MS et al PerfusionMRI the five most frequenasked clinical questions AJR Am J Roentgenol 2013201W495ndashW510

11 Turkbey B Pinto PAMani H et al Prostate cancer value of multiparametric Mimaging at 3 T for detectionmdashhistopathologic correlation Radiology 20102589ndash99

12 Bae KT Intravenous contrast medium administration and scan timing at CT cosiderations and approaches Radiology 201025632ndash61

13 Riederer SJ Bernstein MA Breen JF et al Three-dimensional contrast-enhancMR angiography with real-time fluoroscopic triggering design specifications atechnical reliability in 330 patient studies Radiology 2000215584ndash593

14 DeMarco JK Schonfeld S Keller I et al Contrast-enhanced carotid MR angioraphy with commercially available triggering mechanisms and elliptic centphase encoding AJR Am J Roentgenol 2001176221ndash227

15 Prince MR Chenevert TL Foo TK et al Contrast-enhanced abdominal MR agiography optimization of imaging delay time by automating the detectioncontrast material arrival in the aorta Radiology 1997203109ndash114

16 Jost G Endrikat J Pietsch H The impact of injector-based contrast agent admistration on bolus shape and magnetic resonance angiography image qualiMagn Reson Insights 2017101178623X17705894


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FIGURE 1 Experimental setup For hand syringe tests the two stopcocks were mounted one on top of the other to simulate the turning orinsertion motion that the technologists use to flush To mount on the injector the two stopcocks were separated and mounted on the correspondinginjector syringes


saline All were blinded to their injection performance to avoid a learing effect In addition the staff working with the technologists did nsee the flow rate over time curve displayed on the measurement systecontrol panel during the test to avoid accidental feedback by body laguage To avoid fatigue injections were performed on a rotating basiA technologist performed a given injection followed by the other members of that group so that no technologist performed 2 consecutive maual injections Each participant on a given day performed a total12 manual injections 2 per scenario for the 6 scenarios On the daywhere there were just 2 technologists one of the Bayer observetook a turn so that the rest time was approximately the same for atest groups

Six scenarios with 2 different IV catheters (22 gauge an20 gauge) 2 different contrast volumes (10 and 20 mL) and 2 differeinjection speeds (1 and 5 mLs) were tested The injector and each tecnologist performed each scenario twice (Table 1)

lyetteremi-o-d

eeth

2inn-

n-

Target ParametersFor all 6 scenarios the flow rates over time were continuous

recorded for injector and manual administration The primary targvariable was defined as the average absolute and average absolupercentage deviation from the target flow rate The deviations weadded without considering the direction of deviation Thus the terabsolute refers to the fact that deviations in flow rates above (postive) and below (negative) the target were summed as to their abslute numerical deviation without regard to the plusmn sign so positive annegative deviations did not average out

s-sd

asgdsstes

dn-c-or

TABLE 1 Test Scenarios for Injector and Manual Administrations

Scenario

TargetFlowRate

CMVolume

IVGauge

MRXperionNo Tests

10 Technologists(andashj) No Tests

1 5 mLs 10 mL 22 2 202 5 mLs 20 mL 22 2 203 1 mLs 10 mL 20 2 194 1 mLs 20 mL 20 2 205 5 mLs 20 mL 20 2 206 5 mLs 10 mL 20 2 20

Σ12 Σ119


StatisticsBecause this was a pilot study no statistical hypothesis could b

stated All results are reported descriptively

MaterialsThis study used the following materials injector MRXperio

(VV1010 with a valid calibration sticker) contrast 1 M gadobutr(Gadovist Bayer AG Leverkusen Germany)45 computer LenovG40 equipped with Windows XP (National Instruments Labvie2013 service pack 1 M62x65157I) program Mettler Balance anflow meter (ver04_johnvi saved on May 24 2013 1218 PM) NcDAQ-9147 support frame NI 9215 input module for flow metetransonic flow meters ME2PXl1019 Medrad Calibration 13405ndashand ME2PXl1018 Medrad Calibration 13405ndash2 (Rev Filter on 40 Hmeasuring 20 data points per second [1 data point each 005 secondscale Mettler Toledo PR 2003 Delta Range (control number 1334RevmdashPR2003 DR SNR 1125360581 TDNR 26473122ndash0 last cabrated December 2014) Stopcock 565311 IV catheters (20 gaugBD Ref 381134 and 22 gauge BD Ref 381123) SVTS (swabable valvtransfer set) Halkey Roberts swabable valve 245204024 13-in lengof MR 65115 VS tubing (0075-in ID 0125-in OD)

RESULTSThe flow rates over time for all 6 scenarios are shown in FigureWhile the flow rates over time of the 2 injector administrations

each scenario were almost identical those for the intraindividual and iterindividual manual injections varied widely

Contrast injections were followed by a saline flush The time iterval between the administration of contrast and saline was clearly viible as a trough in the flow rate curves between these 2 injection phaseThis was best shown in the 5 mLs scenarios (scenarios 1 2 5 an6) performed by the injector

The target flow rate of 5 mLs in scenarios 1 2 5 and 6 wquickly reached by the injector with some slight deviation durinramp-up and ramp-down whereas the flow rate of 5 mLs was reacheonly in rare cases by manual injection The target flow rate of 1 mL(scenarios 3 and 4) was precisely reached by the injector with almono gap between the contrast and saline phase whereas the flow ratover time for manual injections varied up to 31 mLs

The total injection duration depends on the contrast volume anthe injection speed In the 1 mLs scenarios (scenarios 3 and 4) the ijector precisely injected the contrast within 10 and 20 seconds respetively In the 5 mLs scenarios the injection duration with the inject


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Documents

Accuracy and Repeatability of Automated Injector Versus