Scientific Session 6Ang iog raphy/lmag inglAlternativeContrast Agents

Sunday, April 7, 20023:15 PM ·4:45 PMModerator(s):John A. Kaufman, MD

Hans - Joachim Wagner, MD, PhD

MATERIALS AND METHODS: In 7 domestic pigs (53 ± 9 kgbody weight, BW) continuous spiral CTs of the chest andabdomen were performed using 2 ml/kg BW gadobutrol(Gadovist, Schering, Germany, Berlin) given by singleintravenous injection over an auricular vein (Siemens SomatomPlus 4; slice: 5 mm, table feed: 7.5 mm, reconstruction

SIS

Abstract No. 423:26PM

CONCLUSION: Contrast enhanced CT with 1 M gadobutrolresulted in an excellent contrast peak enhancement. CT usinggadobutrol is feasible and a possible alternative to iodinatedcontrast material.

increment: 5 mm; CARE Bolus protocol). One week later thesame animals were examined under the same protocol usingiopromide (Ultravist 300; Schering, Berlin, Germany; 2 mVkgBW).ln 3 additional animals serial CTs were performed usinggadobutrol on day I and iopromide on day 7 to detect contrastmedia kinetics, peak enhancement and time enhancement­product in important vascular regions and parenchymal organs(e.g. abdominal aorta, inferior caval vein, liver and renalparenchyma. Peak enhancement (net increase compared withnative baselines) were measured in Hounsfield units (HU) indefined regions of interest (ROI). Additionally, diagnosticquality and accuracy ofthe CTs were evaluated on a two-stepscale by three independent blinded investigators.

RESULTS: In vivo, the mean peak enhancement 0, 5, 10,30,60 and 120 seconds in the abdominal aorta after injection of2 ml/kg BW gadobutrol and iopromide was 40, 200, 224, 261,118,95 HU and 41,232,298, 152, 143, 123 HU respectively.All CTs using gadobutrol were classified as diagnostic withexcellent differentiation of vascular and parenchymalstructures.

X-Ray Angiography with 1 M Gadobutrol. Results from aComparative Study with Iodinated Contrast Media.M. Kalinowski, Philipps-University Hospital. Marburg,Germany· 0. Kress· T Wels • K.J. Klose· H.J. Wagner

PURPOSE: To evaluate prospectively diagnostic accuracy of1M gadobutrol as a contrast agent for intraarterial x-ray digitalsubtraction angiography (DSA) in comparison to iodinated,non-ionic contrast media and 0.5 M gadolinium-DTPA.

MATERIALS AND METHODS: Flush arteriograms(ascending, descending, abdominal aorta, iliac and femoralarteries) and selective angiograms (carotid, renal and visceralarteries) were obtained from bilateral femoral arterial access(5 F sheaths) in ten domestic pigs (70 kg body weight). Digitalsubtracted angiograms were obtained during injection ofnon­diluted I M gadobutrol, 300 mg Vml iopromide, or 0.5 Mgadopentetate. Injection parameters (volume and velocity)were similar for all three contrast agents. In paired arteries,two different contrast media were used during the sameangiographic run. Diagnostic quality and accuracy of theangiograms were evaluated on a three-step scale by threeindependent blinded investigators.

RESULTS: Sufficient angiographic images were obtained in90% of cases using iodinated contrast material. Gadobutrolachieved sufficient non-selective angiograms in 64%. Selectiveangiograms were sufficient in 98% using iodinated contrastmaterial, 90% using I M Gadobutrol and 48% using 0.5 MGd-DTPA. Adverse reactions to any of the used contrastagents were not noted.

CONCLUSION: I M Gadobutrol solution allows x-ray digitalsubtraction angiography with diagnostic accuracy equivalentto 300 mg/ml iodinated contrast media, if selective injectionsare performed. Flush aortograms are of inferior image qualityto iodinated contrast material. I M Gadobutrol achievessignificantly better image quality compared with 0.5 Mgadolinium solutions. Originally published in 200 I ScientificProgram of the Radiological Society of North America.Reprinted with permission ofthe RSNA.

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Specialty Trends in Central Venous Access DevicePlacement: An Analysis of Medicare Utilization Data.R. Duszak Jr., West Reading Radiology Associates, Reading,PA, USA· M.R. Mabry

PURPOSE: To evaluate trends in central venous accessplacement with respect to provider specialty.

MATERIALS AND METHODS: The most recent 5-yearperiod ofavailable Medicare data (1995-1999) was reviewed,summarized, and analyzed for trends in central venous accessdevice placement services. Codes 36489 (for non-tunneledcatheters) and 36533 (for implanted devices: tunneled cathetersand ports) were selected as markers of all central venousaccess services, and their frequency ofutilization was analyzedwith respect to physician provider specialty.

RESULTS: For non-tunneled catheters, the annual number ofservices for Medicare beneficiaries increased from 492,621 to572,202 (16.2%) during the 5-year period. These were mostoften placed (in order) by anesthesiologists, general surgeons,and radiologists. While services by other specialty providersremained stable, services by radiologists increased 759%(11,863 to 101,861). This increase is larger than that for allnon-tunneled catheter placement services nationwide. Forimplanted devices, the annual number placed nationallyincreased from 99,642 to 156,389 (57.0%). These were placedmost often (in order) by general surgeons, radiologists, andvascular surgeons. While services by most specialists increased,services by radiologists increased by far the most, from 5,536to 33,759 (510%). This increase amounts to nearly one-halfthe increase in implanted central access devices nationwide.

CONCLUSION: Recent national increases in central venousaccess services have been largely absorbed by radiologypractices. The growth in central venous access services byradiologists has rapidly outpaced that by other specialties.Radiologists are now among the most frequent providers ofcentral venous access services nationwide.

Evaluation of 1 M Gadobutrol as Contrast Agent forComputed Tomography. Results from a ComparativeAnimal Study.M. Kalinowski, Philipps-University Hospital, Marburg,Germany· O. Kress· T Wels • K.J. Klose· H.J. Wagner

PURPOSE: Aim of the underlying study was to evaluateprospectively the efficacy ofgadobutrol as contrast agent fordiagnostic chest and abdominal CT compared to iodinatedcontrast media iopromide in a porcine animal model.

Multislice Spiral CT Angiography in PAOD: Comparisonof Different Imaging Modalities.H.R. Portugaller, Univ. Clinic ofRadiology, Graz, Austria·1. Tauss • H. Schoellnast· K.A. Hausegger· W Amann

PURPOSE: To evaluate the potential of different multisliceCT - angiography (CTA) imaging modalities in the detectionofhemodynamically significant ~70%) lesions ofthe aortoi liac,femoropopliteal and ii'tfrapopliteal arteries.

MATERIALS AND METHODS: Forty-one patients (35 men,6 women; mean age 68 years) with peripheral arterial occlusivedisease (PAOD) underwent multislice spiral-CTA and digitalsubtraction angiography (DSA) from the infrarenal aorta tothe supramalleolar region. CT-parameters were 4x2.5 mmcollimation, 1.5 cm table-increment (pitch 6) and 1.25 mmreconstruction-increment. Volume rendering technique (VRT),maximum intensity projection (MIP) and MIP together withaxial CT-studies were reviewed for significant stenoses andocclusions. DSA was the standard of reference.

into ten anatomic segments and the length of patent vesselvisible in each segment recorded. The average length of patentvessel in each segment was calculated. The measurementsobtained from the two modalities were compared using a two­tailed paired Student's t-test. The number of segmentsinterpreted to be partially or completely patent was calculated.

RESULTS: The average length of patent vessel was greaterwith CTA than with DSA in each segment for both readers.This difference was statistically significant (p<0.05) in all buttwo segments (below knee popliteal artery and tibo-peronealtrunk). CTA identified at least partial filling of 23.5% moresegments than DSA (584/620 vs. 473/620). 33.0% more vesselsegments were interpreted as being completely patent withCTA than with DSA (512/620 vs. 385/620).

CONCLUSION: Visualization of calf vessels is vital in thediagnostic work-up of patients with peripheral vasculardisease.In our experience CTA is superior to DSA in the visualizationof calf run-off in patients with severe proximal occlusion.

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Comparison of DSA and CTA in the Visualization ofCalf Runoff in Patients with Proximal Occlusive ArterialDisease.ML Martin, University ofBritish Columbia, Vancouver,BC, Canada· AL Thompson· C. Keogh· K.H. Tay· L.S.Machan

PURPOSE: CT angiography (CTA) will become more widelyutilized in investigating peripheral vascular disease with theincreasing availability of multi-detector CT scanners. Thesuperior contrast resolution of CT compared to DSA mayallow better visualization of faintly opacified arteries inpatients with severe proximal disease. We compared the abilityof CTA and DSA to identify patent calf vessels in patientswith occlusive inflow disease.

MATERIALS AND METHODS: Patients who underwent bothCTA and DSA of the lower extremities within three monthsofeach other and were found to have long-segment occlusion(>5 cm) of an above knee artery were considered for entryinto our study. Patients who had undergone a revascularizationprocedure between studies were excluded. Twenty-eightpatients with unilateral (n=25) or bilateral (n=3) occlusionswere enrolled. Two radiologists reviewed both studies in ablinded manner. The below-knee arterial supply was divided

RESULTS: In 37 patients, 210 lesions were detected by DSA(84 stenoses, 126 occlusions). Considering all ;::':70% lesions,VRT/ MIP/ MIP+axial CT revealed 12(71 %)/ 14(82%)/15(88%) of 17 aortoiliac, 45(90%)/47(94%)/49(98%) of50femoropoplitealand 114(80%)/121(85%)/127(89%) of 143infrapopliteallesions. On VRT/ MIP/ MIP+axial CT, 9/49/I I aortoiliac, 9/ 10/ 9 femoropopliteal and 65/ 49/ 47infrapopliteal vessel sections were considered to be ;::':70%stenotic whereas DSA showed no significant lumen narrowing.Distinction of stenoses and occlusions was impossible at 0/5(29%)/ 1(6%) aortoiliac, 1(2%)/4(8%)1 0 femoropoplitealand 35(24%)/ 38(26%)/ 41 (29%) infrapopliteal lesions onVRT/ MIP/ MIP+axial CT-studies.

CONCLUSION: Multislice CTA is helpful in detectinghemodynamically significant lesions in PAOD. However,lesion overestimation is a frequent feature ofall CTA-imagingmodalities. At infrapopliteal arteries, stenoses and occlusionsare likely to be confused. Since axial CT-studies yielded mostcorrect positive results, they should always be reviewedadditionally.

A Real Time Detection Method of Air Contamination ofCarbon Dioxide Used in Angiography.W C. Culp Jr., U Texas Medical Branch· W C. Culp Sr.

PURPOSE: Detection of air contamination of CO2

used forangiography has not been practical in clinical settings. Thelow solubility of nitrogen and oxygen can lead to vapor lockand ischemia if used in vessels. A gas analyzer commonlyused in anesthesia is successfully applied to this problem.

MATERIALS AND METHODS: Seven samples of CO2 withknown air contamination levels of50%, 30%, 20%, 10%,5%,2%, and 0% were used in a "bag system" ofCO

2delivery. 140

sample values each of CO2

, N2

, and 02 were obtained at thefinal side port next to the angiographic catheter as each testgas was slowly pushed through the system over five I minuteperiods. These were compared to the expected values using astandard Raman scatter type multiple gas analyzer. An equalnumber of air samples were measured in a similar manner.

RESULTS: Nitrogen levels were reliably detected indicatingcontamination with as little as 2% air, median registered valueI .3%. The relative error between observed and theoreticalvalues showed a modest correlation with the magni tude of thevalues, Pearson correlation coefficient 0.41, P = 0.02. Oxygenlevels were reliably detected indicating contamination with aslittle as 5% air, median registered value 1%. The relative errorshowed no correlation with magnitude ofthe values, p = 0.18.Detection of 02 and N

2changes took from 3 to 6 seconds to

register precise quantities and showed graphic change almostimmediately. CO

2values were uniformly higher than the true

values at all levels except 100%, P = <0.000 I.The relativeerror between observed and theoretical values is related to themagnitude ofthe values, Spearman Rank correlation coefficient0.98, Pearson correlation 0.94, p = <0.0001. Quantificationof CO

2changes took from 14 to 22 seconds.

CONCLUSION: Raman scatter'gas analyzer machines do anexcellent job ofdetecting air contamination ofCOr Clinicallyimportant amounts of N

2and 02 contamination are readily

detected by this practical method. The current machine doesnot directly measure CO

2well enough to detect small levels of

contamination.

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3-D Rotational Angiography for Peripheral Applications.J C. van den Berg, St Antonius Hospital, Nieuwegein, TheNetherlands· FL. Moll

PURPOSE: To evaluate the value of3D rotational angiography(3D-RA) in the assessment of patients to be treatedendovascularly for occlusive or aneurysmatic arterial disease.

Validation of an Angiographic Method for EstimatingFlow to Distal Tissue Beds.S. T. Crawford, Mallinckrodt Institute ofRadiology, St.Louis, MO, USA • R. V. Olsen· T.K. Pilgram· JR. Duncan

PURPOSE: We propose a method of using angiographicfindings to estimate the flow reductions to distal tissue bedsin patients with peripheral vascular disease (PVD).

MATERIALS AND METHODS: Twenty patients with PVDunderwent lower extremity angiography. For each patient,three readers used the proposed scheme to estimate flowwithin 23 separate vessel segments from the aorta to thepedal vessels. This scheme includes not only an assessmentof stenoses and occlusions but also includes corrections forcollaterals. Each reviewer scored each angiogram twice. Flowreductions to muscles in the thigh and calfwere calculated bymultiplying the estimated flows in the series of vessels thatled to these regions. The consistency of the scoring schemewas assessed using Pearson correlation coefficients for intra­and interobserver variability. The scoring scheme was alsoused to estimate the ankle-brachial index (ABI) and theseestimates were compared to the known ABIs.

RESULTS: Overall the scoring scheme demonstrated verygood intra- and interobserver agreement. Correlationcoefficients were typically >0.9. In general, the correlationcoefficients for proximal vessel segments were higher than

MATERIALS AND METHODS: Seventeen patients (15 male,2 female; mean age 71.5 years) with known peripheralaneurysmatic arterial disease, and 84 patients (64 male, 20female; mean age 58.5 years) with known peripheral occlusivearterial disease underwent 3D-RA and subsequent stent(graft)placement. Sizing and procedure monitoring was performedusing 3D-RA.

RESULTS: In all cases 3D-RA yielded diagnostically sufficientimages. Diameter and length measurements could be performedin all cases. Measurements added 5-10 minutes to proceduretime. 3D-RA allowed choice ofoptimal X-ray tube angulationin all cases. Control angiography showed adequate treatmentof the stenosis or exclusion of the aneurysm in all patients.Good appositioning of the stentgraft at the proximal and distallanding zones was seen in cases treated for aneurysmaticdisease. No per-procedural complications were seen. Extensivepre-interventional workup could be reduced, and calibratedangiography or CT angiography was not required (anymore).Although the amount ofcontrast for one rotational run exceededthe amount for a single, classic angiographic injection, thetotal amount of contrast was reduced because one run wassufficient. The time necessary for performing the 3D­reconstruction was short, and should not be considered a lossof time, as the necessity to perform various runs (as withconventional angiography) is lacking with the 3D-RAtechnique.

CONCLUSiON: 3D-RA appears to be a valid tool in the pre­and per-interventional assessment of patients treatedendovascularly for occlusive and aneurysmatic arterial disease.

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Rapidly-Heparin-Releasing and Heparin-AdherentAngiographic Catheters: Assessment of Anti­Thrombogenic Effect.J.K. Han, Seoul National University Hospital, Seoul, Korea• K.H. Lee· c.J Yoon • Y.R. Byun • H. Moon

PURPOSE: We evaluated the effectiveness of two types ofnovel anti-thrombogenic angiographic catheters, rapidly­heparin-releasing and heparin-adherent catheters.

MATERiALS AND METHODS: We developed rapidly­heparin-releasing catheter by coating polyurethane catheterwith the blend of amphiphilic heparin-derivative (heparin­deoxycholic acid) and hydrophilic hydrogel block copolymer.Heparin-adherent catheter was developed by coating with theblend of hydrophobic heparin-derivative (heparin­octadecylamine) and organic solvent. For in vitro assessment,platelet aggregation test and fibrin formation test wereperformed with both types of heparin-coated catheters andnon-coated catheter (as control) and the results wereinterpreted using scanning electron microscopy. For in vivoassessment, five pairs of coated and control catheters (5French) were prepared for each type of heparin-coatingsystem. Coated and control catheters were inserted in bothfemoral arteries at the same time in an anesthetized mongreldog and clamped for 30 minutes after aspiration of 10 cc ofblood. After removal, each catheter was flushed with 20 cc ofsaline on filter paper and the mass of fresh thrombi wasmeasllred.

those for distal vessel segments. The scoring scheme also hadexcellent agreement for estimated flows to distal tissue beds.The fmding that the agreement was better for a series ofvesselsthan it was for individual segments suggests that the observedvariability in vessel segments may reflect different reviewersassigning the same lesions to different segments rather thandisagreement about the severity of the disease. The estimatedABIs were similiar to the measured ABIs in all but threecases. These outliers include two cases where the measuredABI was> I due to noncompressible vessels and the estimatedABI correctly reflected PVD. In the third case, the ABI wasnear normal due to a patent peroneal artery and our estimatedABI was abnormally low because our estimation method failedto factor in the peroneal artery.

CONCLUSiON: The proposed angiography scoring schemeyielded reproducible estimated flow reductions to distal tissuebeds. We plan to use this scheme as a research tool forevaluating new methods of assessing and treating PVD.

RESULTS: On in vitro assessment, neither platelet aggregationnor fibrin formation was observed in both types of heparin­coated catheters compared to strong reactions in controlcathcter. On in vivo assessment, the mass of thrombi ITomrapidly-heparin-releasing (0.148 ± 0.020 gram, mean ± SD) orheparin-adherent (0.118 ± 0.022) catheters was lesser thanthat ITom control catheter (0.235 ± 0.023 and 0.245 ± 0.014,respectively) in all pairs (p < 0.05 and p < 0.05, respectively,Wilcoxon matched-pairs signed-ranks test).

CONCLUSiON: Both types of new anti-thrombogenicangiographic catheters were effective in vitro and in vivo.

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