* Corresponding author: Takahiko Kamata, Department of Cardiology, Matsushita Memorial Hospital, Sotojima 5-55, Moriguchi, Osaka 570-8540, Japan. Tel: +81-66992-1231; Fax: +81-66992-4845; Email: kamata.takahiko@jp.panasonic.com © 2014 mums.ac.ir All rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.  

   

SerialMyocardial Imaging after a SingleDose of Thallium‐201TakahikoKamata1*,TatsuyaKawasaki1,TadaakiKamitani1,HirokiSugihara11 DepartmentofCardiology,MatsushitaMemorialHospital,Osaka,Japan

ARTICLEINFO ABSTRACT

Articletype:CaseReport

Although thallium‐201 exercise scintigraphy has been established for thedetection of myocardial ischemia and viability, little is known regarding themyocardialthallium‐201kineticsduringangioplasty.Herein,wereporta77‐year‐oldmanwithanginapectoris, inwhomserialmyocardial imagingaftera singledose of thallium‐201was helpful in identifying not only the culprit lesion andmyocardialviability,butalsothedynamicchangesinmyocardialperfusionduringangioplasty.Thallium‐201imagesafterexerciseshowedaperfusiondefectintheinferiorwall,withatrivialredistribution3hoursaftertheexerciseandamarkedimprovement 24 hours later. Coronary angiography, performed 27 hours afterexercise scintigraphy, showed severe stenosis in the right coronary artery.Guidewire crossing of the lesion interrupted the antegrade flow, which wasrestored after balloon dilation and stent implantation. Thallium‐201 images, 2hoursafterangioplasty(i.e.,30hoursafterexercise),showedadecreasedtraceruptake in the inferior wall, which improved the next day (i.e., 48 hours afterexercise).Cardiacbiomarkerswerenegativeintheclinicalcourse.

Articlehistory:Received:6Jan2014Revised:6Mar2014Accepted:13Mar2014

Keywords:AngioplastyKineticsMyocardialischemiaThallium

►Pleasecitethispaperas:KamataT,KawasakiT,KamitaniT,SugiharaH.SerialMyocardialImagingafteraSingleDoseofThallium‐201.AsiaOceaniaJNuclMedBiol.2014;2(2):127‐130.

IntroductionAlthough thallium‐201 exercise scinti‐

graphy has been established for detectingmyocardial ischemia and viability (1), little isknown regarding the kinetics of thallium‐201during angioplasty.Herein,we report a patientwithanginapectoris,inwhomserialmyocardialimagingafterasingledoseofthallium‐201washelpful in identifyingnotonlytheculprit lesionand myocardial viability, but also the dynamicchanges in myocardial perfusion duringangioplasty.

CasereportA 77‐year‐old man was referred to our

hospital with a 1‐month history of exertionalchest pain. The patient reported that the chestpainhadoftenoccurredseveralminutesafterhestartedtowalk.Thepaingraduallyspreadtotheshouldersandjawandlastedforafewminutesafter exercise cessation. The patient also had a

previous history of hypertension anddyslipidemia. He occasionally consumedalcoholicdrinksanddidnotsmoke.

Themedicationsincludedamlodipine(5mgdaily), carvedilol (10 mg daily), temocapril (2mg daily), aspirin (100 mg daily), andlansoprazole(15mgdaily).

The patient’s vital signs and physicalexamination results were unremarkable. Theresults of electrocardiogram, chest radiograph,and echocardiogram were normal, similar toroutine blood examination results. Coronarycomputed tomography angiography showedmultiple stenotic lesions,whichweremoderateto severe in severity. To determine the culpritlesion, maximal symptom‐limited exercisescintigraphywiththallium‐201wasscheduled.

The exercise began at a workload of 25watts, which increased by 25 watts every 2minutes, using a bicycle ergometer under

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Figure1.Thallium‐201bull's‐eyemapafter exercise showsaperfusiondefect in the inferiorwall (A).A trivial redistribution isobserved3hoursafterexercise(B).Thebull’s‐eyemap24hoursafterexerciseshowsamarkedimprovementintheinferiorwall(C).Anotablydecreasedtraceruptakeisseenintheinferiorwall2hoursafterangioplasty(i.e.,30hoursafterexercise)(D).Theinferioruptakeisimproved20hoursafterangioplasty(i.e.,48hoursafterexercise)(E).

continuous monitoring with the Mason‐Likarlead system. Exercise was discontinued due tochest pain with horizontal ST‐segmentdepression of 1 mm in inferior leads. Themaximalworkload,heartrate,andrate‐pressureproduct were 50 watts, 83 bpm, and 13,944,respectively.

Thallium‐201 (111 MBq or 3 mCi) wasinjectedintravenouslyatthepeakofexercise.Atotal of 36 images over a 180‐degree anteriorarc were acquired 5 minutes or 3 hours aftertracer injections with a digital gamma camera,equipped with a low‐energy, high‐resolution,and parallel‐hole collimator. The acquisitionlasted50beatsperprojection,storedinamatrixof 64×64 pixels, and the images werereconstructed using a Hanning filter withoutattenuationorscattercorrection.

Thebull's‐eyemapafterexerciseshowedaperfusiondefectintheinferiorwall(Figure1a).Theredistributionofthallium‐201wastrivial3hours after the exercise (Figure 1b), althoughleft ventricular asynergy was not detected inechocardiography. Additional scintigraphicimaging was performed 24 hours after theexercise,showingamarkedimprovementintheinferiorwall(Figure1c).

Coronaryangiography,performed27hoursafter exercise scintigraphy, showed mild‐to‐moderatestenosisofthemid‐portionoftheleftanterior descending artery and the leftcircumflexartery,andalsoseverestenosisoftheposterolateral branch of the right coronaryartery (Figure 2a, arrow; Video S1). Guidewirecrossingofthelesioninterruptedtheantegradeflow(Figure2b;VideoS2),whichwas restoredimmediatelyafterballoondilationwithina fewminutes.

Coronary dissection, detected on opticalcoherence tomography (Figure 2c), wassuccessfullytreatedbystenting(Figures2dand2e; Video S3). The bull's‐eye map, with anacquisition time of 60 beats per projection,which was reconstructed 2 hours afterangioplasty (i.e., 30 hours after exercise withthallium‐201), showed a decreased traceruptake in the inferiorwall (Figure1d),withanimprovementwithinthenextday(i.e.,48hoursafter the exercise) to the same level as in thepre‐angioplasty thallium‐201 images (Figure1e).

Cardiac biomarkers were negative duringtheclinicalcourse.Thedayafterangioplasty,thelevelsofhigh‐sensitivitycardiactroponinTand

Serial Thallium Imaging Kamata T et al

Asia Oceania J Nucl Med Biol. 2014; 2(2):127-130. 129

Figure2.Rightcoronaryangiographyshowstheseverestenosisoftheposterolateralbranchwithantegradeflow(A,arrow).Theantegradeflowdisappearsafterguidewirecrossingofthelesion(B).Opticalcoherencetomographyafterballoonangioplastyshowscoronarydissection(C).Stentimplantationwassuccessfullyperformedwithnoresidualstenosis(D).Nodissectionisdetectedonopticalcoherencetomography(E).creatine kinase MB isoenzyme were 0.007ng/ml (reference range <0.014 ng/ml) and 7IU/l (reference range <25 IU/l), respectively.The patient has been in a stable conditionwithout any chest symptoms for more than 6months.

DiscussionThe initial distribution of thallium‐201 in

myocardium is determined by regionalmyocardial blood flow and tracer content; thedeterminant of thallium‐201 redistribution is abalance between the influx (i.e., continuedmyocardial extraction from systemiccirculation) and efflux (i.e., the intrinsicmyocardialwashout)(2‐4).

In an experimental study on anesthetizeddogs(2),theextractionfractionofthallium‐201was almost constant over a wide range ofcoronary perfusion pressure, whereas theintrinsic washout rate of thallium‐201 wasmarkedly prolonged in association withdecreased coronary perfusion pressure. Thesefindingsmay indicate that theefflux, comparedtoinflux,isamajordeterminantofthallium‐201myocardial redistribution except for patientswith a very low coronary perfusion pressure,suchas thosewith acutemyocardial infarction.

Given the rapid recovery of thallium‐201washoutrateaftertheimprovementofcoronaryperfusionpressure(2),angioplastymightaffectthe serial images of thallium‐201 ifadministeredbeforesuchinvasiveprocedures.

Inourcase,changesinthallium‐201uptakein the inferior wall after exercise (3 and 24hours after exercise) indicated that the culpritlesion was at the posterolateral branch of theright coronary artery,withmyocardial viabilityin the inferior wall (1). Interestingly, thallium‐201 images, acquired 30 and 48 hours aftertracerinjections,wereacceptableinqualityandwereindicativeofatransientdecreaseoftraceruptakeintheinferiorwallafterangioplasty.

Although the exact involved mechanismremainsunclear,wemaysafelyconsiderthat itwas not the result of distal embolism, butincreased thallium‐201 washout rate afterreperfusion (2, 5), possibly accompanied byhyperemia due to the right coronary dilation,following transient artery occlusion duringangioplasty (6). It is not surprising that theredistribution of thallium‐201was observed inthe inferiorwallonthe followingday,owingtothedisappearanceofanincreasedwashoutrateafter angioplasty. This speculation is, in part,supported by the lack of a slow flow after

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balloon angioplasty or stenting and lack ofelevated cardiac biomarkers in the clinicalcourse.

Ourcasehighlightsthatserialimagingafterasingledoseof thallium‐201maybehelpful inidentifying not only the culprit lesion andmyocardial viability, but also the dynamicchanges in myocardial perfusion duringangioplasty.

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