Abstracts of Current Literature

VASCULAR-ARTERIALMRA Diagnosis

Takayasu Arteritis: Diagnosis WithBreath-Hold Contrast-enhanced Three-dimensional MR Angiography.Ichiro Yamada, Tsuneaki Nakagawa,Yoshiro Himeno, et al. Magn Reson Im-aging 2000; 11:481–487. (I.Y., Depart-ment of Radiology, Faculty of Medi-cine, Tokyo Medical and Dental Uni-versity, 1-5-45 Yushima, Bunkyo-ku,Tokyo 113-8519, Japan)

• The purpose of the study was todetermine the diagnostic accuracy ofbreath-hold contrast-enhanced three-di-mensional (3D) magnetic resonance(MR) angiography in Takayasu arteritis.Thirty patients suspected of havingTakayasu arteritis were examined withMR angiography and conventionalangiography. Takayasu arteritis was di-agnosed in 20 of these patients. MR an-giography was performed using a 1.5-Tsystem after bolus injection of 0.1mmol/kg of gadodiamide. MR angiog-raphy clearly depicted various vascularlesions in the aorta and its majorbranches in all 20 patients with Taka-yasu arteritis. It also depicted pulmo-nary artery lesions in 10 (50%) of the 20patients. MR angiography accurately de-picted 323 (98%) of 330 arteries, but 7(2%) stenotic arteries were overesti-mated as occluded. The sensitivity andspecificity of MR angiography for thediagnosis of Takayasu arteritis wereboth 100%. Breath-hold contrast-en-hanced 3D MR angiography clearly de-picts various vascular lesions in both thesystemic and pulmonary arteries inTakayasu arteritis, thus allowing a defin-itive diagnosis of Takayasu arteritis.Authors’ Abstract

Estimation of Pressure Gradients inPulsatile Flow From Magnetic Reso-nance Acceleration Measurements.Jean-Pierre Tasu, Elie Mousseaux, An-nie Delouche, et al. Magn Reson Med2000; 44:66–72. (J.P.T., CIERM, Hôpitalde Bicêtre, Université, Paris-Sud. 78 ruedu Général Leclerc, 94275 Le KremlinBicêtre Cedex, France)

• A method for estimating pressure gra-dients from MR images is demonstrated.Making the usual assumption that the flow-ing medium is a Newtonian fluid, and withappropriate boundary conditions, the iner-tial forces (or acceleration components of theflow) are proportional to the pressure

gradients. The technique shown here isbased on an evaluation of the inertial forcesfrom Fourier acceleration encoding. Thismethod provides a direct measurement ofthe total acceleration defined as the sum ofthe velocity derivative vs. time and the con-vective acceleration. The technique was ex-perimentally validated by comparing MRand manometer pressure gradient measure-ments obtained in a pulsatile flow phantom.The results indicate that the MR determina-tion of pressure gradients from an accelera-tion measurement is feasible with a goodcorrelation with the true measurements (r 50.97). The feasibility of the method is dem-onstrated in the aorta of a normal volunteer.Authors’ Abstract

Stents

Magnetic Resonance Monitoring ofStent Deployment In Vitro Evaluationof Different Stent Designs and StentDelivery Systems. Christoph Manke,Wolfgang R. Nitz, Markus Lenhart, etal. Invest Radiol 2000; 35:343–351. (C.M.,Department of Radiology, Klinikumder Universität, Franz-Joseph-Strauss-Allee 11, 93042 Regensburg, Germany)

• Rationale and Objectives: To evaluateMR imaging features of commercially avail-able stents before, during, and after in vitrodeployment as a step toward MR-guidedstent deployment. Methods: Fourteen stentswere deployed in a phantom under MRmonitoring at 1.5 T by using a gradient-echosequence. Device visibility was rated on afour-point scale (excellent, fair, poor, notvisible). Results: The Memotherm stent andthe rolling membrane (RM) Wallstentshowed excellent stent visibility and at leastfair scores for artifact-induced narrowing ofthe stent lumen. Three stents (Palmaz, AVE,Easy Wallstent) showed excellent visibilityof the stent but no visible lumen. Five stents(Strecker, Accuflex, Hemobahn, Passager,Sinus) displayed fair visibility. The deliverycatheters of four stent systems (Smart, Vas-cucoil, Symphony, ZA) displayed severeblack hole artifacts. Conclusions: The imagingfeatures of several stent systems might besuitable for MR-guided intervention. TheMemotherm and the Wallstent RM combinegood visibility of the stent and the lumen.Authors’ Abstract

MR Imaging in the Presence of Vascu-lar Stents: A Systematic Assessmentof Artifacts for Various Stent Orienta-tions, Sequence Types, and FieldStrengths. Thomas Klemm, Stephan

Duda, Juergen Machann, et al. J MagnReson Imaging 2000; 12:606–615. (FritzSchick, Department of Diagnostic Radi-ology, University of Tubingen, Hoppe-Seyler-Str. 3, 72076 Tubingen, Ger-many)

• A systematic evaluation of the po-tential quality of magnetic resonance im-ages recorded in the presence of metallicstents was performed on a low-fieldopen imager operating at 0.2 T and on ahigh-field closed unit operating at 1.0 T.Eight different stent types were exam-ined by two-dimensional gradient-echosequences with echo times of 4 and 10msec and by a fast spin-echo technique.In addition, a three-dimensional gradi-ent-echo sequence was applied with anecho time of 2.4 msec. A set of sequenceand slice parameters was used on bothscanners. Thus, artifacts due to suscepti-bility effects depending on the magneticfield strength could be distinguishedfrom radiofrequency shielding effects inthe lumen of the stents (independent ofthe field strength). Nine different or-thogonal orientations of the stent axisand the image (in terms of slice, read,and phase-encoding direction) weretested, and the artifacts (extension of sig-nal void and visibility of the lumen)were compared. The optimal strategy forvisualization of vascular and perivascu-lar regions outside the stents was fastspin-echo imaging with the stent axisand read direction parallel to the staticfield. Susceptibility-induced signal voidin gradient-echo images was minimalusing the three-dimensional approach.Increased transmitter amplitudes aboveusual values provided clearly improvedinsight in the lumen using gradient-echosequences.Authors’ Abstract

Endovascular Stent-Grafts

MR Evaluation Ex Vivo and In Vivoof a Covered Stent-Graft for Abdomi-nal Aortic Aneurysms: Ferromag-netism, Heating, Artifacts, and Veloc-ity Mapping. Lena Engellau, JohanOlsrud, Sara Brockstedt, et al. J MagnReson Imaging 2000; 12:112–121. (L.E.,Department of Radiology, UniversityHospital Lund, 221 85 Lund, Sweden)

• Magnetic resonance imaging (MRI)safety was evaluated at 1.5 T in a coverednickel titanium stent-graft (Vanguard)used for endovascular treatment of ab-dominal aortic aneurysms (AAAs). Imag-

Abstracts of Current Literature

396

ing artifacts were assessed on MRI withcontrast-enhanced (CE) three-dimensional(3D) MR angiography (MRA) and spiralcomputed tomography (CT) in 10 patientsas well as ex vivo. Velocity mapping wasperformed in the suprarenal aorta andfemoral arteries in 14 patients before andafter stent-graft placement. For compari-son it was also performed in six healthyvolunteers. No ferromagnetism or heatingwas detected. Metal artifacts caused min-imal image distortion on MRI/MRA. Theartifacts disturbed image evaluation on CTat the graft bifurcation and graft limbjunction. No significant differences inmean flow were found in patients beforeand after stent-graft placement. Our studyindicates that MRI at 1.5 T may be per-formed safely in patients with the (Van-guard) stent-graft. MRI/MRA providesdiagnostic image information. Velocitymapping is not included in our routineprotocol.Authors’ Abstract

Utility and Reliability of Endovascu-lar Aortouniiliac with FemorofemoralCrossover Graft for Aortoiliac Aneu-rysmal Disease. Thomas F. Rehring,David C. Brewster, Richard P. Cambria,et al. J Vasc Surg 2000; 31:1135–1141.(D.C.B., One Hawthorne Place, Suite111, Boston, MA 02114)

• Objective: The purpose of this studywas to determine the early efficacy ofendovascular aortouniiliac stent graftswith femorofemoral bypass graft in thetreatment of aortoiliac aneurysmaldisease. Methods: We analyzed 51 con-secutive patients from January 1997 toMarch 1999 with a mean follow-up of15.8 months. Patients ranged in age from44 to 93 years (mean, 75 years) with amean aortic aneurysm diameter of 6.2cm. Technical success was achieved in 50patients; one patient required conver-sion to open repair intraoperatively. Weplaced 28 custom-made and 22 commer-cial devices. The mean operative timewas 223 minutes. The endograft was ex-tended to the external iliac artery in 42%of cases. The contralateral common iliacartery was occluded using either aclosed covered stent or intraluminalcoils. Results: The median hospital staywas 4 days with an average intensivecare unit stay of 0.25 days. There wereno operative mortalities. Two patientsdied during follow-up from unrelatedconditions. Endoleaks occurred in 11 pa-tients (22%); seven patients (14%) re-quired intervention (four catheter based,three operative). Other complications oc-curred in 38% of patients but werelargely remote or wound related. Onefemorofemoral bypass graft occludedimmediately postoperatively as a resultof an intraprocedural external iliac dis-

section yielding a 98% primary patencyand 100% secondary patency. Clinicalsuccess was achieved in 88% of patients.Conclusions: These data suggest thatthis strategy represents a reliablemethod of repair of aortoiliac aneurys-mal disease and extends the capability ofan endoluminal approach to patientswith complex iliac anatomy.Authors’ Abstract

Vascular Surgery

Carotid-subclavian Bypass Graftingwith Polytetrafluoroethylene Graftsfor Symptomatic Subclavian ArteryStenosis or Occlusion: A 20-year Expe-rience. Ali F. AbuRahma, Patrick A.Robinson, and Tucker G. Jennings. JVasc Surg 2000; 32:411–419. (A.F.A.,3160 MacCorkle Ave., SE, Suite 603,Charleston, WV 25304)

• Background and Purpose: Since theadvent of subclavian artery percutane-ous transluminal angioplasty@stenting,several authorities advocate it as thetreatment of choice for patients withsubclavian artery disease, claiming re-sults equal to or better than those ofreconstructive vascular surgery. How-ever, most of their quoted surgical seriesincluded patients who may have otherbrachiocephalic disease who weretreated nonuniformly by means of vari-ous bypass grafts with different grafts inthe same series (eg, Dacron, polytetra-fluoroethylene [PTFE], or vein). In thisstudy, we analyze the long-term resultsof a large series of carotid-subclavian by-pass grafts for subclavian artery diseasein which PTFE was uniformly used; thestudy can be used as a future referenceto compare the results of subclavian ar-tery percutaneous transluminalangioplasty/stenting. Patient Populationand Methods: Fifty-one patients withsymptomatic subclavian artery disease(40 occlusions and 11 stenoses) whowere treated with carotid-subclavian by-pass grafts (PTFE [Goretex]) during a20-year period were analyzed. Graft pa-tency was determined clinically and con-firmed with Doppler scanning pressuresand duplex ultrasound scanning. Thecumulative patency, overall survival,and symptom-free survival rates werecalculated with the life table method. Re-sults: Indications for surgery were armischemia in 34 patients (67%), vertebro-basilar insufficiency (VBI) in 27 (53%),and symptomatic subclavian steal in 7(14%). A combination of arm ischemia andVBI occurred in 17 (33%) of these patients.The mean follow-up was 7.7 years with amedian of 7.0 years (range, 1–19 years).The 30-day morbidity rate was 6%, withno perioperative stroke or mortality. Im-mediate relief of symptoms was achieved

in 100% of patients; however, four patients(8%) had late recurrent symptoms (threewith VBI). The primary patency and sec-ondary patency rates at 1, 3, 5, and 10years were 100%, 98%, 96%, and 92% and100%, 98%, 98%, and 95%, respectively.The symptom-free survival rates at 1, 3, 5,and 10 years were 100%, 96%, 82%, and47%, respectively. The overall survivalrates at 1, 3, 5, and 10 years were 100%,98%, 86%, and 57%. The mean hospitalstay was 3.5 days in the late 70s and 80sand 2.1 days in the 90s (P , .001). Conclu-sions: Carotid-subclavian bypass graftswith PTFE grafts for subclavian artery dis-ease are safe, effective, and durable andshould remain the procedure of choice,particularly in good-risk patients.Authors’ Abstract

Carotid

Fluoroscopically Triggered Contrast-enhanced 3D MR DSA and 3D Time-of-Flight Turbo MRA of the CarotidArteries: First Clinical Experiences inCorrelation with Ultrasound, X-rayAngiography, and EndarterectomyFindings. Franz A. Fellner, ClaudiaFellner, Ralf Wutke, et al. Magn ResonImaging 2000; 18:575–585. (F.F., Depart-ment of Diagnostic Radiology,Friedrich-Alexander-University Erlan-gen-Nurnberg, Maximiliansplatz I,D-91054, Erlangen, Germany)

• The aim of this article was to obtaininitial experiences with fluoroscopicallytriggered contrast-enhanced (CE) 3D MRDSA with elliptical centric k-space orderand 3D time-of-flight (TOF) turbo MRAof the carotid arteries. In this prospectivestudy we examined 16 consecutive pa-tients with suspicion of atheroscleroticdisease involving the carotid arteries.Ultrasound was available in all, x-rayangiography in 12, surgical correlationin 9, and intraoperative x-ray angiogra-phy in 4 patients. All examinations weredone on a 1.5 T unit applying: transverseplain 3D TOF turbo MRA and coronalCE MRA with fluoroscopic triggering.Combining head and neck array coilsallowed the visualization of supraaorticarteries from the aortic arch to the circleof Willis. MRA results (maximum inten-sity projections) were compared with x-ray angiography, ultrasound, and in-spection of endarterectomy specimens.Volume rendering was performed in se-lected cases additionally. Agreement be-tween CE MRA, 3D TOF turbo MRA andx-ray angiography regarding stenoses ofthe internal and external carotid arterywas very good. CE MRA was able todetect correctly intracranial stenoses, butdelineation of the aortic arch and proxi-mal common carotid arteries was some-times reduced. Volume rendering was

Abstracts • 397Volume 12 Number 3

suited for visualization of MRA imagesproviding a realistic three-dimensionalimpression. In conclusion, high-resolu-tion fluoroscopically triggered CE MRAas non-invasive technique is another im-portant step on the way to replace inva-sive x-ray angiography for the evalua-tion of atherosclerotic carotid arterydisease. High resolution 3D TOF turboMRA might be a helpful adjunct to in-crease the diagnostic reliability for thecarotid bifurcation.Authors’ Abstract

Magnetic Resonance Angiography Isan Accurate Imaging Adjunct to Du-plex Ultrasound Scan in Patient Selec-tion for Carotid Endarterectomy.Martin R. Back, Jeffrey S. Wilson, Greg-ory Rushing, et al. J Vasc Surg 2000;32:429–440. (M.R.B., Division of Vascu-lar Surgery, University of South FloridaCollege of Medicine, Harbourside Med-ical Tower #650, 4 Columbia Dr.,Tampa, FL 33606)

• Purpose: The purpose of this studywas to evaluate the accuracy of magneticresonance angiography (MRA) for cate-gorizing the severity of carotid diseaserelative to duplex ultrasound scan andcerebral contrast arteriography (CA) todetermine if MRA imaging could replacethe need for cerebral angiography incases of indeterminate or inadequate du-plex scan imaging. Methods: Seventy-four carotid bifurcations in 40 patientsundergoing 45 carotid endarterectomiesfrom 1996 to 1998 were imaged with du-plex ultrasound scan; MRA (two-dimen-sional neck and three-dimensional intra-cranial, time-of-flight technique); andbiplanar, digital subtraction cerebralarteriography. Studies were blindly re-viewed by one reader who used estab-lished threshold velocity criteria for theduplex scan and the North AmericanSymptomatic Carotid EndarterectomyTrial method for MRA and CA to deter-mine the percentage of diameter reduc-tion of the internal carotid artery (ICA).Disease severity was grouped into fourcategories (,50, 50%–74%, 75%–99% ste-nosis and occlusion), and the results ofMRA and duplex ultrasound scan werecompared with CA. Results: Sensitivity,specificity, positive predictive value, andnegative predictive value for detectionof .50% ICA stenosis were 100%, 96%,98%, and 100% for MRA and 100%, 72%,88%, and 100% for duplex ultrasoundscan, respectively; similarly, for detec-tion of .75% ICA stenosis values were100%, 77%, 76%, and 100% for MRA and90%, 74%, 72%, and 91% for duplex ul-trasound scan, respectively. Both MRAand duplex ultrasound scan accuratelydifferentiated all cases of .95% stenosis(n 5 7) from occlusion (n 5 4). Short

length ICA flow gaps were present onMRA in all cases of 75% to 99% stenosisand one half of cases of CA-defined 50%to 74% stenosis. In patients with 50% to74% stenosis, the mean angiographic ste-nosis was significantly greater when aflow gap was present on MRA (64% 66%) versus no flow gap (57% 6 7%) (P 5.04). There was overall agreementamong duplex ultrasound scan, MRA,and CA in 73% of carotids imaged. Ofthe 24% discordant results betweenMRA and duplex ultrasound scan, MRAcorrectly predicted disease severity in allcases, and inaccurate duplex ultrasoundscan results were due to overestimationin 83% of cases. The operative plan wasaltered by CA findings in only one pa-tient (2%) after duplex ultrasound scanand MRA. Conclusions: MRA can accu-rately categorize the severity of carotidocclusive disease. Duplex ultrasoundscan facilitates patient selection for ca-rotid endarterectomy in most cases, butadjunct use of MRA improves diagnosticaccuracy for .75% stenoses and may ob-viate the need for cerebral arteriographywhen duplex scan results are inconclu-sive or demonstrate borderline diseaseseverity.Authors’ Abstract

The Causes and Risk of Stroke in Pa-tients with Asymptomatic Internal-Carotid-Artery Stenosis. DomenicoInzitari, Michael Eliasziw, Peter Gates,et al. N Engl J Med 2000; 342:1693–1700.(Henry J.M. Barnett, John P. RobartsResearch Institute, 100 Perth Dr., P.O.Box 5015, London, ON N6A 5K8, Can-ada)

• Background: The causes of stroke inpatients with asymptomatic carotid-ar-tery stenosis have not been carefullystudied. Information about causes mightinfluence decisions about the use of ca-rotid endarterectomy in such patients.Methods: We studied patients with uni-lateral symptomatic carotid-artery ste-nosis and asymptomatic contralateralstenosis from 1988 to 1997. The causes,severity, risk, and predictors of stroke inthe territory of the asymptomatic arterywere examined and quantified. Results:The risk of stroke at five years afterstudy entry in a total of 1,820 patientsincreased with the severity of stenosis.Among 1604 patients with stenosis ofless than 60 percent of the luminal diam-eter, the risk of a first stroke was 8.0percent (1.6 percent annually), as com-pared with 16.2 percent (3.2 percent an-nually) among 216 patients with 60%–99% stenosis. In the group with 60 to 99percent stenosis, the five-year risk ofstroke in the territory of a large arterywas 9.9 percent, that of lacunar strokewas 6.0 percent, and that of cardioem-

bolic stroke 2.1 percent. Some patientshad more than one stroke of more thanone cause. In the territory of an asymp-tomatic occluded artery (as was identi-fied in 86 patients), the annualized riskof stroke was 1.9 percent. Strokes withdifferent causes had different riskfactors. The risk factors for large-arterystroke were silent brain infarction, a his-tory of diabetes, and a higher degree ofstenosis; for cardioembolic stroke, a his-tory of myocardial infarction or anginaand hypertension; and for lacunarstroke, age of 75 years or older, hyper-tension, diabetes, and a higher degree ofstenosis. Conclusions: The risk of strokeamong patients with asymptomatic ca-rotid-artery stenosis is relatively low.Forty-five percent of strokes in patientswith asymptomatic stenosis of 60 to 99percent are attributable to lacunes orcardioembolism. These observationshave implications for the use of endar-terectomy in asymptomatic patients.Without analysis of the risk of strokeaccording to cause, the absolute benefitassociated with endarterectomy may beoverestimated.Authors’ Abstract

Renovascular Disease

Revascularization of Renal Artery Ste-nosis in Patients With Renal Insuffi-ciency. Hashim Dejani, Thomas D.Eisen, and Fredric O. Finkelstein. Am JKidney Dis 2000; 36:752–758. (F.O.F., 136Sherman Ave., New Haven, CT 06515)

• The incidence and prevalence ofend-stage renal disease (ESRD), particu-larly in the elderly population, have con-tinued to increase in the United States. Itis estimated that 10% to 20% of the el-derly patients with ESRD have poten-tially remediable renal vascular disease.The purpose of the present study is toexamine the results of renal artery revas-cularization in 20 patients aged olderthan 55 years with chronic renal failure(serum creatinine level .2 mg/dL) withproximal renal artery stenosis (RAS) di-agnosed by magnetic resonance angiog-raphy (MRA) who underwent surgicalor percutaneous revascularization. Pa-tients were followed up closely in thepostrevascularization period; renal func-tion was monitored and potential com-plications of the procedure were care-fully noted. Four of the 20 patientsdeveloped serious complications, in-cluding 3 patients with clinically signif-icant atheroembolic disease and 1 pa-tient with renal artery dissection. Sevenpatients developed greater than 5%eosinophilia. Five of the 20 patients hada deterioration in renal function 3 to 6months after the procedure, and only 5patients had a reduction in serum creat-

398 • Abstracts March 2001 JVIR

inine concentration 3 to 5 months afterthe procedure. The present study sug-gests that in elderly patients withchronic renal failure and proximal RAS,revascularization of renal vessels is asso-ciated with a high complication rate, andimprovement in renal function occurs inonly 25% of the patients. Whether revas-cularization can slow the rate of progres-sion of renal failure remains uncertainand can only be answered by a largeprospective trial.Authors’ Abstract

VASCULAR—VENOUSThromboembolic Disease

Surgical Intervention Is Not Requiredfor All Patients with Subclavian VeinThrombosis. W. Anthony Lee, Brad-ley B. Hill, E. John Harris, Jr, et al. JVasc Surg 2000; 32:57–67. (CorneliusOlcott IV, Division of Vascular Surgery,Stanford University Medical Center,300 Pasteur Dr., Room H3636, Stanford,CA 94305-5642)

• Purpose: The role of thoracic outletdecompression in the treatment of pri-mary axillary-subclavian vein thrombosisremains controversial. The timing and in-dications for surgery are not well defined,and thoracic outlet procedures may be as-sociated with infrequent, but significant,morbidity. We examined the outcomes ofpatients treated with or without surgeryafter the results of initial thrombolytictherapy and a short period of outpatientanticoagulation. Methods: Patients sus-pected of having a primary deep venousthrombosis underwent an urgent color-flow venous duplex ultrasound scan, fol-lowed by a venogram and catheter-di-rected thrombolysis. They were thenconverted from heparin to outpatientwarfarin. Patients who remained asymp-tomatic received anticoagulants for 3months. Patients who, at 4 weeks, had per-sistent symptoms of venous hypertensionand positional obstruction of the subcla-vian vein, venous collaterals, or both dem-onstrated by means of venogram under-went thoracic outlet decompression andpostoperative anticoagulation for 1month. Results: Twenty-two patients weretreated between June 1996 and June 1999.Of the 18 patients who received catheter-directed thrombolysis, complete patencywas achieved in eight patients (44%), andpartial patency was achieved in the re-maining 10 patients (56%). Nine of 22 pa-tients (41%) did not require surgery, andthe remaining 13 patients underwent tho-racic outlet decompression through a su-praclavicular approach with scalenec-tomy, first-rib resection, and venolysis.Recurrent thrombosis developed in onlyone patient during the immediate period

of anticoagulation. Eleven of 13 patients(85%) treated with surgery and eight ofnine patients (89%) treated without sur-gery sustained durable relief of theirsymptoms and a return to their baselinelevel of physical activity. All patients whounderwent surgery maintained their ve-nous patency on follow-up duplex scan-ning imaging. Conclusion: Not all patientswith primary axillary-subclavian veinthrombosis require surgical intervention.A period of observation while patients arereceiving oral anticoagulation for at least 1month allows the selection of patients whowill do well with nonoperative therapy.Patients with persistent symptoms and ve-nous obstruction should be offered tho-racic outlet decompression. Chronic anti-coagulation is not required in thesepatients.Authors’ Abstract

Percutaneous Venous Thrombectomywith the Use of a Balloon Sheath:First In Vitro Investigations of a NewLow-Tech Concept. Joachim ErnstWildberger, Thomas Schmitz-Rode,Henning Schubert, et al. Invest Radiol2000; 35:352–358. (J.E.W., Departmentof Diagnostic Radiology, UniversityHospital, RWTH Aachen, Pau-welsstrasse 30, D-52057 Aachen, Ger-many)

• Rationale and Objectives: To test me-chanical thrombectomy of extensive il-iofemoral and iliocaval thrombi in an invitro flow model with the use of 12-F and18-F balloon sheaths. Methods: Newly de-veloped 12-F and 18-F sheaths were eval-uated in four vessel models (simulation offemoral, iliofemoral, iliocaval, and cavalthrombi by clotted bovine blood in a flowmodel). After retrograde insertion of thesheath and blocking of the vessel proximalto the thrombus by inflating the balloon,mechanical fragmentation was performedcoaxially through the sheath lumen by us-ing a 7-F pigtail rotation device. With anocclusion balloon catheter, residualthrombi were withdrawn to the orifice ofthe sheath and aspirated. Twelve siliconetubes occluded by thrombi were recana-lized in each setting. In the latex model,seven recanalizations were performed. Re-sults: All clots were removed completelywithin a treatment duration of 2 to 14minutes. Fluid loss during the procedurewas 29.6 to 129.3 mL for the femoral flowmodel, 61.9 to 137.2 mL for the iliofemoralmodel, 74.5 to 163.4 mL for the iliocavalmodel, and 102.7 to 236.7 mL for the cavalmodel. No fragments were washeddownstream. In four settings, small resid-ual thrombi were attached to the balloonafter deflation of the sheath. Conclusions:Clot amounts up to 171 g were removedquickly and completely by using theselarge-caliber balloon sheaths. Fluid loss

from aspiration was negligible. Balloon oc-clusion prevented embolization of throm-bus fragments proximal to the sheath. Fur-ther studies are needed to prove theefficacy of this technique in vivo.Authors’ Abstract

Vena Cava Filters

Prophylactic Vena Caval Filters inTrauma: The Rest of the Story.Lazar J. Greenfield, Mary C. Proctor,Andrew J. Michaels, et al. J Vasc Surg2000; 32:490–497. (L.J.G., Departmentof Surgery, University of Michigan,2101 Taubman Center/Box 0346, AnnArbor, MI 48109)

• Objective: The purpose of this studywas to describe outcomes for patients withtrauma who had vena caval filters placedin the absence of venous thromboembolicdisease (group P) and compare them withoutcomes for patients with trauma whohad filters placed after either deep venousthrombosis or pulmonary embolism(group T). Design: The study is a case se-ries of consecutive patients who receivedvena caval filters after traumatic injury.Data were collected prospectively at thetime of filter placement from reports ofdiagnostic studies obtained for clinical in-dications and during the annual follow-upexaminations. Event rate findings arebased on objective tests. Data were ob-tained from the Michigan Vena Cava FilterRegistry. Results: Filters were placed in 385patients with trauma; 249 of these filterswere prophylactic (group P). Event rateswere similar in the two groups. New pul-monary embolism was diagnosed in 1.5%of the patients in group P and 2% of thepatients in group T. Caval occlusion rateswere 3.5% for group P and 2.3% for groupT. In all, 15.6% of the patients in group Phad deep venous thrombosis or pulmo-nary embolism after placement. The fre-quencies of lower extremity swelling anduse of support hose were higher in groupT than in group P (43% vs 25% and 25% vs3.5%, respectively; P , .005). Outcomeswere comparable in the two groups withrespect to mechanical stability of the filter.Conclusions: The prophylactic indicationfor vena caval filter placement in patientswith trauma is associated with a low inci-dence of adverse outcomes while provid-ing protection from fatal pulmonaryembolism. The current challenge is to limitthe number of unnecessary placementsthrough improved methods of riskstratification.Authors’ Abstract

Dialysis Access

Efficacy of Tissue Plasminogen Acti-vator Administration on Patency ofHemodialysis Access Catheters. Pir-


ouz Daeihagh, Jennifer Jordan, G. JohnChen, et al. Am J Kidney Dis 2000; 36:75–79. (Michael Rocco, Section of Ne-phrology, Wake Forest UniversitySchool of Medicine, Medical CenterBlvd. Winston-Salem, NC 27157-1053)

• Patients with end-stage renal dis-ease use hemodialysis catheters for ei-ther temporary or permanent bloodaccess. Recurrent thrombosis and fibrinsheath formation are common causes ofpoor or inadequate blood flow rates thatrequire intervention. We studied the ef-fect of tissue plasminogen activator(tPA) in reestablishing adequate bloodflow rates through nonfunctional vascu-lar catheters in 22 consecutive chronichemodialysis patients. From January 1,1999, to May 20, 1999, there were 56instances in which tPA was used in anattempt to improve blood flow rates. Inall instances, 2 mg of tPA was infusedinto each port of a dual-lumen internaljugular catheter. Dwell time ranged be-tween 2 and 96 hours (median, 24hours), and patient follow-up ranged be-tween 47 and 140 days (median, 133.5days). tPA was effective in establishingadequate blood flow rates (.200 mL/min) during the next dialysis session in49 of 56 cases (87.5%). Seven additionalinterventions were required because ofearly or late tPA failure (one fibrinsheath stripping, one catheter replace-ment for kinking, one catheter replace-ment for central venous stenosis, andfour catheter replacements for persis-tently poor blood flow rates), and eightcatheters were replaced for infection.Thus, further interventions to achieveadequate blood flow rates were requiredin 12.5% of the cases because of early orlate tPA failure. tPA appears to be aseffective as urokinase for reestablishingadequate blood flow rates through he-modialysis catheters that are throm-bosed or have low blood flow rates.Authors’ Abstract

Insufficient Penetration of SystemicVancomycin into the PermCath Lu-men. Bahar Bastani, John Minton,and Shah Islam. Nephrol Dial Transplant2000; 15:1035–1037. (B.B., Associate Pro-fessor of Internal Medicine, Division ofNephrology, Saint Louis UniversityHealth Sciences Center, 3635 Vista Ave-nue. FDT—9N, St Louis, MO 63110)

• Background: Catheter infection is amajor cause of morbidity and catheterloss in chronic hemodialysis patients.There has been a large discrepancy in thecatheter salvage rate, after an episode ofdocumented bacteremia, whether thepatients receive systemic antibiotic aloneor systemic antibiotics concomitant with‘antibiotic-lock technique’ (20–30% vs100%, respectively). To test the hypothesis

that vancomycin may not adequately pen-etrate into the lumen of the catheter, de-spite therapeutic plasma levels, a series ofin-vivo, ex-vivo, and in-vitro experimentswere performed. Methods: We comparedserum and intralumenal (0.3–0.5 mL aspi-rate from venous port of the catheter) van-comycin concentrations in 24 chronic he-modialysis patients, with documentedbacteremia, who had received prior sys-temic vancomycin therapy with 14 similarpatients who had additionally received‘vancomycin-lock technique’ (100 mg/mLof vancomycin in heparin solution) aftereach hemodialysis session. Results: De-spite serum vancomycin concentration of'17 mg/mL in each group, the vancomy-cin concentration in the venous hub of thecatheter was only 0.2 6 0.6 mg/mL in theformer group, in sharp contrast to 125.6 613 mg/mL in the latter group. In the ex-vivo experiment, four uninfected Perm-Caths which had been removed were im-mediately fixed and studied withscanning electron microscopy. No cellularor fibrin barrier could be found at the ter-minal pore of the catheter interfering withthe diffusion of vancomycin from plasmainto the catheter lumen. In the in-vitro ex-periments, three PermCaths filled withstandard heparin solution were incubatedfor 48 h in 100 mL of plasma containing 20mg/mL of vancomycin. Vancomycin con-centration was measured in 0.3–0.5 mLsolution aspirated from each port of thecatheters. Vancomycin concentration was0.2 6 0.1 mg/mL in the aspirated samples.Finally, two PermCaths filled with thestandard heparin solution were incubatedfor 48 h in 100 mL of plasma containing 20mg/mL of vancomycin, after which thecatheters were sectioned at 4-cm intervals.Only the distal 4 cm of the catheters hadvancomycin concentrations of 2 and 5 mg/mL, the remaining segments had levels,0.5 mg/mL. Conclusion: Our results indi-cate that diffusion of vancomycin fromplasma into the hemodialysis catheter isnegligible. Thus, hemodialysis patientswith central venous catheter who have tobe treated for bacteremia with systemicantibiotic therapy must always receive’antibiotic-lock technique’ of the catheterafter each hemodialysis session.Authors’ Abstract

TIPS

Transjugular Intrahepatic Portosys-temic Shunt: Experiences at a LiverTransplantation Center. N. Hidajat,T. Vogl, H. Stobbe, et al. Acta Radio-logica 2000; 41:474–478. (N.H., Depart-ment of Radiology, Charité CampusVirchow-Clinic, Medical Faculty of theHumboldt-University, AugustenburgerPlatz I, D-13353 Berlin, Germany)

• Objective: Transjugular intrahepaticportosystemic shunt (TIPS) placement isan established therapy for portal hyper-tension that leads to variceal bleeding orrefractory ascites. We present experiencesof the role of TIPS at a liver transplantationcenter. Material and Methods: One hundredand ten patients were referred to the Ra-diological Department for TIPSplacement. One of the 110 patients hadrecurrent cirrhosis after liver transplanta-tion with refractory ascites. Function of theTIPS was controlled with Doppler US at 1day, 1 week, 4 weeks and 4 months afterTIPS placement and subsequently every 3months. Shunt insufficiency was sup-posed when the blood flow velocitywithin the stent tract was under 50 cm/sand was an indication for TIPS revision.Results: TIPS was placed in 101 patients.After TIPS placement, 10 patients under-went liver transplantation. While waitingfor the new liver, none of them developedvariceal rebleeding, ascites or other com-plications of portal hypertension. Two ofthe 101 patients had episodes ofrebleeding. The frequency of patients un-dergoing TIPS revision within the firstyear after TIPS placement was 67.5%,within the second year 38.0% and withinthe third year 24.4%. The revisions led tosufficient reduction of the portosystemicpressure gradient. Conclusion: In someliver transplant candidates. TIPS can beuseful in minimizing the risk of complica-tions of portal hypertension during thewaiting time for a liver transplantation.TIPS can be monitored by Doppler US andrevised if occlusion occurs.Authors’ Abstract

Mechanical Thrombectomy of AcuteThrombosis in Transjugular Intrahe-patic Portosystemic Shunts. StefanMuller-Hulsbeck, Michael Höpfner,Carsten Hilbert, et al. Invest Radiol2000; 35:385–391. (S.M.H., Departmentof Radiology, Christian-Albrechts-Uni-versity of Kiel, Arnold-Heller-Strasse 9,24105 Kiel, Germany)

• Rationale and Objectives: To evaluatethe feasibility of mechanical thrombec-tomy with the use of the Amplatz throm-bectomy device (ATD) in restoring pa-tency to acutely thrombosed stent-shunts after transjugular intrahepaticportosystemic shunt (TIPS) placement.Methods: Mechanical thrombectomywith the ATD was performed in 10 con-secutive patients with angiographicallydocumented complete thrombosis of thestent-shunt (mean 6 SD, 6.6 6 3.4 cm),which occurred an average of 2.8 months(range, 0–11 months) after the TIPSprocedure. Results: In all patients, im-mediate restoration of patency of thestent-shunt was achieved after throm-bectomy alone (n 5 1), thrombectomy


plus percutaneous transluminal angio-plasty (PTA; n 5 4), and thrombectomy,PTA, and stenting (n 5 5). The meanactivation time of the ATD was 253 6 43seconds. The pressure gradient for portaldecompression decreased from 23 6 6mm Hg before to 11 6 3 mm Hg after theprocedure. The primary patency ratewas 80% at 3 months and 60% at 11months. Conclusions: Mechanicalthrombectomy with the ATD in acutelythrombosed TIPS is technically feasible.Mechanical thrombectomy is a potentialalternative to thrombolysis.Authors’ Abstract

CARDIAC

Effects of Estrogen Replacement onthe Progression of Coronary-ArteryAtherosclerosis. David M. Her-rington, David M. Reboussin, K.Bridget Brosnihan, et al. N Engl J Med2000; 343:522–529. (D.M.H., Departmentof Internal Medicine, Wake Forest Uni-versity School of Medicine, MedicalCenter Blvd., Winston-Salem, NC27157-1045)

• Background: Heart disease is a majorcause of illness and death in women. Tounderstand better the role of estrogen inthe treatment and prevention of heart dis-ease, more information is needed about itseffects on coronary atherosclerosis and theextent to which concomitant progestintherapy may modify these effects. Meth-ods: We randomly assigned a total of 309women with angiographically verifiedcoronary disease to receive 0.625 mg ofconjugated estrogen per day, 0.625 mg ofconjugated estrogen plus 2.5 mg of me-droxyprogesterone acetate per day, orplacebo. The women were followed for amean (6SD) of 3.2 6 0.6 years. Baselineand follow-up coronary angiograms wereanalyzed by quantitative methods. Results:Estrogen and estrogen plus medroxypro-gesterone acetate produced significant re-ductions in low-density lipoprotein cho-lesterol levels (9.4 percent and 16.5percent, respectively) and significant in-creases in high-density lipoprotein choles-terol levels (18.8 percent and 14.2 percent,respectively); however, neither treatmentaltered the progression of coronaryatherosclerosis. After adjustment for mea-surements at base line, the mean (6SE)minimal coronary-artery diameters at fol-low-up were 1.87 6 0.02 mm, 1.84 6 0.02mm, and 1.87 6 0.02 mm in women as-signed to estrogen, estrogen plus me-droxyprogesterone acetate, and placebo,respectively. The differences between thevalues for the two active-treatment groupsand the value for the placebo group werenot significant. Analyses of several sec-ondary angiographic outcomes and sub-groups of women produced similar

results. The rates of clinical cardiovascularevents were also similar among the treat-ment groups. Conclusions: Neither estro-gen alone nor estrogen plus medroxypro-gesterone acetate affected the progressionof coronary atherosclerosis in women withestablished disease. These results suggestthat such women should not use estrogenreplacement with an expectation of cardio-vascular benefit.Authors’ Abstract

Coronary Stenting Plus Platelet Glyco-protein IIb/IIIa Blockade Comparedwith Tissue Plasminogen Activator inAcute Myocardial Infarction. AlbertSchömig, Adnan Kastrati, Josef Dirsch-inger, et al. N Engl J Med 2000; 343:385–391. (A.S., Deutsches Herzzentrum,Lazarettstr. 36, 80636 Munich, Ger-many)

• Background: Prevention of myocar-dial damage is the main goal of all reper-fusion therapies in patients with acutemyocardial infarction. The relative efficacyof various reperfusion strategies is underintensive investigation. We assessedwhether coronary stenting combined withthe blockade of platelet glycoprotein IIb/IIIa receptors produces a greater degree ofmyocardial salvage than fibrinolysis withan accelerated infusion of alteplase, a tis-sue plasminogen activator. Methods: A to-tal of 140 patients were enrolled in therandomized trial; 71 were assigned to re-ceive a stent plus abciximab, and 69 toreceive intravenous alteplase. The primaryend point was the degree of myocardialsalvage, determined by means of serialscintigraphic studies with technetium Tc99m sestamibi. The secondary end pointwas a composite of death, reinfarction,and stroke within six months afterrandomization. Results: In the group thatreceived a stent plus abciximab, the me-dian size of the final infarct was 14.3 per-cent of the left ventricle (25th and 75thpercentiles, 6.8 and 24.5 percent), as com-pared with a median of 19.4 percent (25thand 75th percentiles, 7.9 and 34.2 percent)in the alteplase group (P 5 .02). This dif-ference was due to the larger salvage in-dex (the percentage of the left ventriclethat was salvaged, divided by the percent-age that was compromised by the initialperfusion defect) in the stent group: 0.57(25th and 75th percentiles, 0.35 and 0.69),as compared with 0.26 (25th and 75th per-centiles, 0.09 and 0.61; P , .001). The cu-mulative incidence of death, reinfarction,or stroke at six months was lower in thestent group than in the alteplase group (8.5vs. 23.2 percent, P 5 .02; relative risk, 0.34;95 percent confidence interval, 0.13 to0.88). Conclusions: In patients with acutemyocardial infarction, coronary stentingplus abciximab leads to a greater degree ofmyocardial salvage and a better clinical

outcome than does fibrinolysis with a tis-sue plasminogen activator.Authors’ Abstract

GASTROINTESTINAL

A Comparison of Colonoscopy andDouble-Contrast Barium Enema forSurveillance after Polypectomy. Sid-ney J. Winawer, Edward T. Stewart,Ann G. Zauber, et al. N Engl J Med2000; 342:1766–1772. (S.J.W., Gastroen-terology and Nutrition Service, Depart-ment of Medicine, Memorial Sloan-Ket-tering Cancer Center, 1275 York Ave.,New York, NY 10021)

• Background: After patients have un-dergone colonoscopic polypectomy, it isuncertain whether colonoscopic examina-tion or a barium enema is the bettermethod of surveillance. Methods: As partof the National Polyp Study, we offeredcolonoscopic examination and double-contrast barium enema for surveillance topatients with newly diagnosed adenoma-tous polyps. Although barium enema wasperformed first, the endoscopist did notknow the results. Results: A total of 973patients underwent one or more colono-scopic examinations for surveillance. Inthe case of 580 of these patients, we per-formed 862 paired colonoscopic examina-tions and barium-enema examinationsthat met the requirements of the protocol.The findings on barium enema were pos-itive in 222 (26 percent) of the paired ex-aminations, including 94 of the 242colonoscopic examinations in which oneor more adenomas were detected (rate ofdetection of adenomas, 39 percent; 95 per-cent confidence interval, 33 to 45 percent).The proportion of examinations in whichadenomatous polyps were detected bybarium enema was significantly related tothe size of the adenomas (P 5 .009); therate was 32 percent for colonoscopic ex-aminations in which the largest adenomasdetected were 0.5 cm or less, 53 percent forthose in which the largest adenomas de-tected were 0.6 to 1.0 cm, and 48 percentfor those in which the largest adenomasdetected exceeded 1.0 cm. Among the 139paired examinations with positive resultson barium enema and negative results oncolonoscopic examination in the same lo-cation, 19 additional polyps, 12 of whichwere adenomas, were detected on colono-scopic reexamination. Conclusions: In pa-tients who have undergone colonoscopicpolypectomy, colonoscopic examination isa more effective method of surveillancethan double-contrast barium enema.Authors’ Abstract

HEPATOBILIARY

Percutaneous Ethanol Injection of theSupplying Artery to Hepatocellular


Carcinoma that is not Amenable toConventional Treatment. Z-Y Lin,J-H Wang, M-Y Hsieh, et al. Br J Radiol2000; 73: 833–839. (Z.Y.L., Departmentof Internal Medicine, Kaohsiung Medi-cal University Hospital, No. 100 Shih-Chuan 1st Road, Kaohsiung 807, Tai-wan, Republic of China)

• The purpose of this study was toevaluate the clinical usefulness of ultra-sound-guided percutaneous ethanol in-jection of the supplying artery (PEISA)to the tumour in the palliative manage-ment of hepatocellular carcinoma (HCC)that is not amenable to conventionaltreatments. A total of 23 cases of HCC,measuring from 3.1 cm to larger than 15cm (median 5.4 cm) in 17 cirrhotic pa-tients, were treated by PEISA. PEISAwas used to control rapid growth of thetumour in seven patients and to reduceabdominal discomfort caused by rapidexpansion of the tumour in 10 patients.Tumours with arterial Doppler signalspersisting after PEISA underwent re-peated treatment. The follow-up periodranged from 2–48 months. PEISA wasachieved in 69 out of 76 attempts(90.8%). The amount of ethanol injectedon each occasion ranged from 2.5–33 ml.Follow-up colour Doppler scanningshowed complete elimination of tumourDoppler signals in 22 out of 23 lesions(95.7%). Following treatment, one tu-mour disappeared, 13 tumours shrankand nine tumours were unchanged insize. All patients with abdominal dis-comfort had relief after treatment. Thecommon complications of PEISA werelocal pain and fever. In conclusion,PEISA is effective at treating painfulHCC unsuitable for conventionaltreatment.Authors’ Abstract

High-dose Percutaneous Ethanol In-jection Therapy of Liver Tumors: Pa-tient Acceptance and Complications.N. Elgindy, H. Lindholm, and P. Gun-vén. Acta Radiol 2000; 41:458–463. (P.G.,Department of Surgery; KarolinskaHospital, SE-171 76 Stockholm, Swe-den)

• Purpose: To study the safety of high-dose ethanol injections in liver tumors andtheir acceptability as out-patient proce-dures under local anesthesia. Material andMethods: Twenty-nine patients received20–95 mL of 95% ethanol by 62 percuta-neous injections under local anesthesia.Pain was assessed by a visual analoguescale from 1 to 10 for 33 of the sessions.Side effects, complications, post-treatmentrequirement of parenteral analgesics, andhospital stay (discharge the same day orlater) were recorded. The sessions werecompared to 80 injections of ,20 mL ofethanol in 18 patients. Results: High-dose

injections with an average volume of 39mL gave a mean pain score of 5.1, with aweak relationship between pain andvolume. Other side effects and complica-tions were unrelated to the ethanol dose.They comprised 1 syncopation, 1 occasionof hypoventilation requiring antidote toopiates, 12 short episodes of nausea orvomiting without need for i.v. fluids, 2instances of sepsis, and 1 abscess that wasdrained percutaneously. Thirty-nine of the62 sessions were performed in day care.Ethanol was given in high doses withoutapparent complications after or shortly be-fore liver resections (3 patients in eachgroup), and on 4 occasions in 2 HIVcarriers. Low-dose injections resulted in amean pain score of 4.7 with the same re-quirement of i.v. analgesics as high doses,fewer instances of nausea and no infec-tious complications. Conclusion: High-doseethanol injections in patients with livermalignancy had no mortality and a rea-sonable complication rate. They could begiven without general anesthesia, often inday care.Authors’ Abstract

NEUROINTERVENTION

Neurologic Complications of CerebralAngiography: A Retrospective Studyof Complication Rate and Patient RiskFactors. A.-M. Leffers and A. Wag-ner. Acta Radiol 2000; 41:204–210.(A.W., Department of Diagnostic Neu-roradiology, University of Copenhagen,Rigshospitalet, Blegdamsvej 9, DK-2100Copenhagen, Denmark)

• Purpose: To evaluate the neurologiccomplication rate and individual patientrisk factors in cerebral angiographies us-ing the digital subtraction angiography(DSA) technique and non-ionic contrastmedia in a department with many radi-ologists in training. Material and Methods:A retrospective study of 483 cerebral an-giographic examinations in 454 patientswas carried out. The following parame-ters were registered: sex and age of thepatient, indication for the angiography,cerebral CT diagnosis, laboratory data,type of anesthesia, type of angiographicprocedure, level of training of the an-giographer, number of participating an-giographers, type of catheters, numberof vessels catheterized, number of expo-sures, use of compression series, totalamount of contrast media, diagnosis ofthe angiogram, complications and dura-tion of complications. Results: The fre-quency of all neurologic complicationswas 2.3%, the frequency of persistentneurologic deficits was 0.4%. Non-neu-rologic complications were observed in14.7% of the examinations. Of all theparameters studied, the only factor thatsignificantly increased neurologic risk

was a normal angiogram, a finding weare inclined to ascribe to chance. Perfor-mance of a compression series showed atrend towards increasing the neurologicrisk. Conclusion: This study showed acomplication rate of persistent neuro-logic deficits of 0.4% which is in accor-dance with other recent reports. A com-pression series should not be performedroutinely, but only on special indication.This study confirms the low risk of cere-bral angiography when performed in aneuroradiological department using theDSA technique and non-ionic contrastmedia.Authors’ Abstract

TRAUMA

Identification of Trauma Patients atRisk of Thoracic Aortic Tear by Mech-anism of Injury. Tristram G. Horton,Stephen M. Cohn, Michael P. Heid, etal. J Trauma 2000; 48:1008–1014.(S.M.C., Ryder Trauma Center, UM/JMMedical Center, Daughtry Family De-partment of Surgery, 1800 N.W. 10thAvenue, Suite T-227, Miami, FL 33136)

• Objective: We sought to identify po-tential measurable on-scene informationthat would assist clinicians in the iden-tification of patients at risk for thoracicaortic tear (AT) after vehicular trauma.Methods: Data were prospectively col-lected at the scene of 295 motor vehiclecrashes from 1995 to 1999. There were 34cases (12%) with AT. Scene data con-sisted of vehicle maximal crush, maxi-mal intrusion into the occupant com-partment, change in velocity (Delta V)and principal direction of force. Thoracicaortic injuries were confirmed radio-graphically or at autopsy. Crash factorswere analyzed for correlation with ATby logistic regression. Results: Delta V.20 mph and near-side impact were thefactors having the strongest correlationwith thoracic aortic injury. Delta V .20mph (n 5 32 with AT) had an oddsratio 5 6.4, (P , .01). Near impact (n 520 with AT) had an odds ratio 5 2.3, (P, .05) and intrusion 15 inches had anodds ratio 5 3.2, P , .05. The sensitivity,specificity, and accuracy of the presenceof near impact, Delta V .20 mph, orboth, were 100%, 34%, and 64%. Thepositive and negative predictive valueswere 16% and 100%, respectively. Therewas no relationship of AT to use of seatbelts or airbags. Conclusion: Thoracic aor-tic injury after vehicular collision can bereliably excluded if near-impact, Delta V20 mph, or intrusion 15 inches are notpresent. Mechanism of injury in the formof crash scene information may aid cli-nicians in identifying individuals at risk


for thoracic aortic tear after vehiculartrauma.Authors’ Abstract

Mortality after Successful Transcathe-ter Arterial Embolization in Patientswith Unstable Pelvic Fractures: Rateof Blood Transfusion as a PredictiveFactor. Yon-Cheong Wong, Li-JenWang, Chip-Jin Ng, et al. J Trauma2000; 49:71–74. (Y.C.W., Chang GungMemorial Hospital, Second Division,Department of Radiology, 5, Fu-HsingStreet, Gueishan, Taoyuan, 33333 Tai-wan)

• Background: To determine the factorspredictive of mortality in patients with un-

stable pelvic fractures after successfultranscatheter arterial embolization. Meth-ods: A retrospective study of pelvic frac-tures between May of 1995 and April of1998 was performed. Of 507 patients, 17who were unstable underwent embo-lization. The success rate of embolizationand the mortality rate after successful em-bolization were reviewed. Predictive fac-tors (contrast medium extravasation, ini-tial blood pressure, Injury Severity Score,timing of external fixation, time to angiog-raphy, volume of blood transfusion, rateof blood transfusion) of the final outcomewere statistically analyzed. Results: Embo-lization was 100% effective in stoppingpelvic hemorrhage. The mortality of pa-

tients treated successfully with emboliza-tion was 17.6%. Among the predictive fac-tors analyzed, only the rate of bloodtransfusion before embolization, 11.3 611.0 U/h (death) versus 3.2 6 1.9 U/h(survival) showed statistical significancewith an odds ratio of 1.62 (95% CI, 1.07–2.46). Conclusion: The success rate of em-bolization was 100% in stopping arterialhemorrhage of unstable pelvic fractures.The survival rate after successful emboli-zation was 82.4%. Patients who had rapidblood transfusion before embolization hada poor final outcome. The risk of dyingincreased by 62% for every 1 unit/h in-crease of transfusion rate.Authors’ Abstract


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