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1 원저 Korean Circulation J 2004;34(12): 관상동맥질환의진단에있어서 Multidetector Computed Tomography 의임상적유용성 이화여자대학교의과대학심장내과내과학교실 오희정 권기환 박시훈 박성훈 이유현유민아 김수현 송지현 김윤정 CT Coronary Angiography Using Multidetector Computed Tomography in Coronary Artery Disease:A Comparative Study to Quantitative Coronary Angiography Hee Jung Oh, MD, Kihwan Kwon, MD, Si-Hoon Park, MD, Seong-Hoon Park, MD, You-Hyun Lee, MD, Min-A Yu, MD, Su-Hyun Kim, MD, Jihyun Song, MD and Yoon-Jung Kim, MD Cardiovascular Center, Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Korea ABSTRACT Background and Objectives:The purpose of the present study was to investigate the diagnostic accuracy of coronary stenoses in patients with ischemic heart disease using multidetector CT coronary angiography (MDCT) in the assessment of coronary artery disease. Subjects and Methods:Forty-three patients (49-72yrs) undergoing conventional coronary angiography (CCA) were included in this study. All patients were premedicated with oral propranolol, mg, to achieve an acceptable heart rate of less than 65 bpm, 1hr before the MDCT. All coronary arteries, including the distal segments and side branches, were assessed with respect to assessability and the presence of significant stenosis (>50%) and the results compared with those of CCA. Results:Of the 645 coronary artery segments scanned, 540 were assessable (84%). A total 44 significant stenoses were detected by CCA and 49 lesions by MDCT. The overall sensitivity and specificity were 77 and 97%, respectively. The overall accuracy for the LAD, RCA and LCX was 94, 98 and 95%, respectively, and there were no differences in the accuracies in each vessel. The sensitivity in the proximal segments was much higher than in the distal segments. A total 15 segments were overestimated by the MDCT due to calcification and the small vessel size. Conclusion:MDCT, with improved spatial and temporal resolutions, and pre-treated with oral beta-blocker, permits the detection of coronary artery stenoses with a high degree of accuracy. (Korean Circulation J 2004; 34(12): ) KEY WORDS:Coronary angiography;coronary artery stenoses;coronary stenosis. 논문접수일 :2004 년 5 월 19 일수정논문접수일 :2004 년 8 월 9 일심사완료일 :2004 년 9 월 21 일교신저자 : 권기환, 서울양천구목동 이화여자대학교의과대학심장내과내과학교실전화 :(02) 전송 :(02) kankadin@ewha.ac.kr 1167

2 서론 관상동맥질환을진단하는데있어현재까지의진단방법은관혈적관상동맥조영술이었다. 이시술은현재까지의여러진단방법중에가장정확한방법이지만침습적인방법으로서, 드물지만시술중에부정맥이나관상동맥박리등의치명적인부작용이생길수있다. 또한침습적인동맥천자와삽관이필요하며이는환자의불편함과입원을요하는단점이있다. Multi-detector CT coronary angiography(mdct) 가 1999 년에처음등장하여비침습적인방법으로관상동맥의영상을얻을수있게되었다. 1)2) 조영제를주입하고후향적심전도동조화 (Retrospective ECG gating) 하에 MDCT 를시행하여관상동맥조영술과유사한영상을얻는것이가능해져서이를이용한관상동맥질환의진단률이높게보고되고있다. 3-5) 그러나, MDCT 를통한관상동맥질환의진단에는여러가지제한점이있다. 직경이 2 mm 이하인혈관의병변을분석하기에는 MDCT 의해상도가낮고, 혈관의석회화는인공물을일으켜 (blooming artifact) 혈관내경을실제보다좁아보이게하는문제점이있다. 또한심장박동에따른관상동맥의움직임 (motion artifact) 이있거나부정맥이있으면 MDCT 를성공적으로시행하기어렵다. 분석가능한양질의관상동맥영상을얻는데방해가되는가장중요한요인으로는환자의빠른심장박동수와그에따른관상동맥의움직임이있으며, 그외에혈관주위의석회화등이보고되었다. 4) 최근에는심장박동수가낮을수록 MDCT 의관상동맥질환에대한민감도와특이도를향상시킬수있다는연구보고가있다. 6)7) 이에본연구에서는베타차단제를투여해서심장박동수를조절후 MDCT 를시행하였으며, 관상동맥질환의진단에있어서실제허혈성심질환환자를대상으로관상동맥조영술과비교함으로써 MDCT 의정확도를알아보고자하였다. 대상및방법 대상혈성심질환으로입원한환자중에서관상동맥조영술시행예정인 43명 ( 남자 30명, 여자 13명 ) 의환자 를대상으로하였으며, 평균연령은 56±11.15세였다 (49~72 세 ). 대상환자들의임상적특성은 Table 1과같다. 혈역학적으로불안정하거나심방세동등의부정맥이있거나심장박동수가분당 65회이상이거나, 75세이상인경우는대상에서제외되었다. 분당심박동수가 65회이하로조절되는환자에서조영증강전 CT를시행하여관상동맥에심한석회화가보이고, 이부위의칼슘 score가 300 이상으로측정된환자도대상에서제외하였다. 모든환자는 MDCT 시행후 48시간내에관상동맥조영술을시행받았다. MDCT 시행전에모든환자에서 propranolol 40 mg에서 80 mg까지경구복용하여 65회이하의심장박동수를유지하였다. Multidetector Computed Tomography(MDCT) scan protocol 16-slice MDCT(SOMATOM Sensation, Siemens Medical System, Germany) 를이용하여, 검출기폭조절은 mm, 겐트리회전시간 (gantry rotation time) 은 420 ms, 360 도회전당 table 이동속도는 2.8 mm로심전도동조화를하면서촬영하였다. 18G 카테터를이용하여상완정맥으로 80 ml의비이온성조영제 (Omnipaque 300;Nycomed, Cork, Ire-land) 를초당 4 ml의속도로주입하고이어서 20 ml의생리식염수를초당 4 ml 의속도로주입하였다. 상행대동맥에서 bolus tracking 을실시하여 100 HU(Hou-sefield Unit) 되는시점으로부터 6초후영상을얻기시작하였고, 호흡정지하에폐동맥간부터심저까지단면영상을얻었다. Table 1. Baseline characteristics of study patients (n=43) Age (year) 56±11.15 Male (%) 30(70%) Stable angina 08(19%) Unstable angina 24(56%) Acute MI 04(09%) Old MI 07(16%) Risk factor DM 12(28%) Hypertension 21(49%) Smoking 15(35%) Hyperlipidemia 26(60%) Body mass index (kg/m 2 ) 24.48±2.500 MI: myocardial infarction, DM: diadetes mellitus 1168 Korean Circulation J 2004;34(12):

3 영상의재구성은심장재구성소프트웨어 (Syngo, Software Version A50 or A60, Siemens Medical System) 를이용하여후향적심전도동조화하에재구성하였다. 특이도, 양성예측도, 음성예측도, 그리고정확도를계산하였다. 결과 영상재구성과분석심장주기에서 R파와 R파간격의약 40~80% 사이에서여러개의영상세트를재구성을한후최고의질을보이는영상세트를선택하여분석하였다. 영상은횡단면영상과다면상재구성 (multiplanar reformation, MPR) 방법에의해 American College of Cardiology/American Heart Association(ACC/AHA) 의분류법에따른 15 관상동맥분절에서협착에관하여분석하였다 (Fig. 1). 각관상동맥의분절의유의한협착은관상동맥내경의 50% 이상으로정의하였다. 관상동맥조영술관상동맥조영술은 MDCT 시행 48시간내에시행하였다. 관상동맥의분절도 ACC/AHA 분류법에따라분석하였다 (Fig. 1). 관상동맥각분절의유의한협착은관상동맥내경의 50% 이상협착으로정의하였다. 관상동맥조영술결과는 Quantitative Coronary Angiography(QCA;Philips Medical Systems, Eindthoven, Netherlands) 를이용하여분석되었다. 결과분석본연구의목적이관상동맥협착증의진단에있어 MDCT 의정확성평가이므로, 관상동맥조영술과비교하여유의한관상동맥협착증의진단에있어민감도, RCA Fig. 1. Segmental anatomy of right coronary artery, and left coronary artery with left main, left anterior descending, and left circumflex according to American Heart Association (Quoted from Kopp, et al 11) ). RCA: right coronary artery, LM: left main coronary artery. LM Lcircumflex LAD 대상환자들의 CT 스캔시간은 21±3 초였고, MDCT 를시행하는동안모든환자에게서심각한부작용은없었다. 모든환자에서심장박동수를분당 65 회미만으로유지했으며, 평균심장박동수는분당 56±10 회였다. 총 645개의분절중 84% 인 540개분절에서 MDCT 로분석가능하였으며, 105 개분절에서분석이불가능하였는데심장박동에따른관상동맥의움직임에의한경우 (motion artifact, 35분절 :33%;LAD:5 분절 ; LCX:14 분절 ;RCA;16 분절 ), 혈관의크기가작은경우 ( 평균혈관직경 <2.0 mm;55 분절 :53%), 그리고 scan 범위설정의오류와잘못된조영제투여시기등의기술적인문제 (15 분절 :14%) 로인한경우였다. MDCT 로분석가능한분절을보인총 36명의환자들중관상동맥조영술에서관상동맥협착이있었던경우는 22명이었다 (1-vessel disease;9 명, 2-vessel disease;9 명, 3-vessel disease;4 명 ). 각분절별로보면관상동맥조영술결과총 44 개관상동맥분절에서 Table 2. Diagnostic accuracy of MDCT in diagnosis of coronary artery stenosis according to the vascular territory All evaluable segments LAD LCX RCA Segments (n) Lesions by CCA (n) 010 Lesions by MDCT (n) 009 False positive (n) 001 Sensitivity (%) Specificity (%) PPV (%) NPV (%) Accuracy (%) CCA: conventional coronary angiography, MDCT: multidetector computed tomography, PPV: positive predictive value, NPV: negative predictive value, LAD: left anterior descending artery, LCX: left circumflex artery, RCA: right coronary artery 1169

협착이있었는데 MDCT 에서는 49개분절에협착이있었으며, 관상동맥조영술결과와비교할때 MDCT 의진단정확도는평균민감도 77%, 평균특이도 97%, 평균정확도 95% 였다.

Diagnostic accuracy of MDCT in diagnosis of coronary artery stenosis according to the vascular position Proximal segments* Mid segments* Distal segments* Segments (n) 144 108 288 Lesions by CCA (n)

CCA: conventional coronary angiography, MDCT: multidetector computed tomography, PPV: positive predictive value, NPV: negative predictive value, *: proximal, mid & distal segments were defined as

총 15분절에서위양성의결과가나왔는데 (LAD: 10분절, LCX:4 분절, RCA:1 분절 ), 11개분절에서관상동맥의석회화가원인이었고 (Fig. 2), 4개분절에서평균혈관직경이 2.0±0.8 mm로작은혈관이었다 (Table 4).

4 협착이있었는데 MDCT 에서는 49개분절에협착이있었으며, 관상동맥조영술결과와비교할때 MDCT 의진단정확도는평균민감도 77%, 평균특이도 97%, 평균정확도 95% 였다. 민감도는좌전하행지, 우관상동맥, 좌회선지에서각각 85%, 80%, 64% 였으며, 특이도는각각 95%, 99%, 98%, 그리고정확도는각각 94%, 98%, 95% 로각혈관에따른차이는없었다 (Table 2). 관상 Table 3. Diagnostic accuracy of MDCT in diagnosis of coronary artery stenosis according to the vascular position Proximal segments* Mid segments* Distal segments* Segments (n) Lesions by CCA (n) Lesions by MDCT (n) False positive (n) Sensitivity (%) Specificity (%) PPV (%) NPV (%) Accuracy (%) CCA: conventional coronary angiography, MDCT: multidetector computed tomography, PPV: positive predictive value, NPV: negative predictive value, *: proximal, mid & distal segments were defined as below(fig. 1). Proximal segment: 1,5,6,11. Mid segment: 2,7,12. Distal segment: 3,4,8,9,10,13,14,15 동맥분절의위치별로분류하였을때는민감도의경우근위부혈관에서 100% 로원위부혈관의 65% 보다높았으나특이도나정확도에서는큰차이가없었다 (Table 3). 총 15분절에서위양성의결과가나왔는데 (LAD: 10분절, LCX:4 분절, RCA:1 분절 ), 11개분절에서관상동맥의석회화가원인이었고 (Fig. 2), 4개분절에서평균혈관직경이 2.0±0.8 mm로작은혈관이었다 (Table 4). 고 본연구결과전체관상동맥분절중 84% 에서 MDCT 로분석가능한영상을얻을수있었으며, 관상동맥조영술결과와비교하였을때도높은정확성을보였다. 이러한결과는관상동맥질환을의심하는환자에서적절한전처치를통하여심장박동수를조절하고심한석회화 Table 4. Causes for false positive results in the coronary segments Coronary artery Calcification Small vascular diameter 찰 LAD (n=10) 09 (090%) 1(10%) LCX (n=4) 01 (025%) 3(75%) RCA (n=1) 01 (100%) 0(00%) Overall (n=15) 11 (073%) 4(27%) LAD: left anterior descending artery, LCX: left circumflex artery, RCA: right coronary artery A B C Fig. 2. Patient with minimal left anterior descending artery lesion. A: curved multiplanar reconstruction shows significant stenosis at LAD with calcification (arrow). B: cross section of involved vessel. Calcification with soft tissue plaque consist of the lumen. Lumen is narrow (arrow). C: however, conventional angiography shows minimal LCA lesion. This false positive finding of MDCT is due to heavy calcification of vessel (arrow) Korean Circulation J 2004;34(12):

5 병변이없을경우 MDCT 를통해서도관상동맥협착증을진단할수있는가능성을제시하는것이다. 본연구결과평균민감도는 77%, 특이도는 97% 그리고정확도는 95% 로높은진단의정확성을보였으며이는이전 16 slice MDCT 의결과와유사하였다. 8)9) 본연구결과에서진단의정확성을향상시킬수있었던것은먼저 16 slice MDCT 를사용한점을들수있다. 이전연구들에서는 4 slice MDCT 를사용하였으며, 그결과는최근개발된 16 slice MDCT 를사용한결과들보다정확성이낮게보고되고있다. 4-7)10)11) 4-slice MDCT 를이용한때와비교하여 16-slice MDCT 의경우검출기폭조절이 1 mm 에서 0.75 mm 로좁아지고공간해상도가 mm에서 mm로좋아졌고, 한번의겐트리회전당얻을수있는횡단면영상의수가 4개에서 16개로증가함으로써스캔시간이 40초에서 20초로짧아져서조영제의사용량을줄일수있으며환자가숨을참아야되는시간이더짧아져서호흡으로인한영향을줄일수있으며시간해상도는 125~250 ms 에서 105~210 ms 로향상되어심근의움직임에의한인공물을줄일수있다는장점이있다. 12)13) MDCT 의영상의질을결정하는또하나의중요한요소가심장박동수이다. Schroeder 등 6) 과 Nieman 등 7) 은심장박동수와 MDCT 영상의질이반비례함을보고했으며심박수가 65회이하일때최적의분석가능한영상을얻을수있음을보여줬다. 심장박동수가중요한이유는 MDCT 의시간해상도가심장박동수의제한을받기때문이다. 겐트리회전시간이 500 ms일때 MDCT 의시간해상도는 250 ms이며한번의심장박동을하나의영상으로재생가능하다 (single phase reconstruction). 심장박동수가 65회이상일때는시간해상도가 125 ms로증가되어야하며두번의심장박동에서얻어진데이터를하나의이미지로재생하는방법 (bi-phase reconstruction) 이사용된다. Kuettner 등 10) 의결과는한번의심장박동을통해서영상을구성할때 (single phase reconstruction) 영상의질이더좋았다고보고했다. 또한낮은심장박동수에서는이완중기 (mid diastolic) 의심근의움직임이없는시간 (motion free window) 이길어서정지영상에가까운영상을얻을수있다. 따라서베타차단제를전처치하여심장박동수를 65 회이하로만들었을때이완중기의시간이길어져서영상의질이높아진다. 본연구에서는베타차단제를사용하여평균심 장박동수를평균 56회로감소시킴으로써높은민감도와특이도를얻을수있었다. 3개의관상동맥은심장의주기에따라각각다른움직임을보인다. 좌회선지와우관상동맥은심장고랑 (coronary groove) 에위치하고있기때문에좌전하행지보다이완기에더빨리움직인다. 이는이완기끝의심방수축이있기때문이다. Achenbach 등 14) 은 EBCT(electron beam CT) 에서심장주기에각각관상동맥의다른움직임을분석했는데인공물을줄이려면 acquisition window 시간이짧아야한다고지적했는데 MDCT 에서도이점은적용된다. 본연구에서특이한점은우관상동맥의정확도가 98% 로가장높았다. 이는분석가능했던우관상동맥에서베타차단제로심근의움직임을배제할수있었고또한우관상동맥의직경이다른혈관에비해컸던점때문으로생각된다. 본연구결과총 15 분절에서위양성의결과가나왔는데 (LAD:10 분절, LCX:4분절, RCA:1 분절 ), 11 개분절에서관상동맥의석회화가원인이었고, 4분절에서평균혈관직경이 2.0±0.8 mm 로작은혈관이었다. 석회화는영상의질을결정하는또다른중요요소이다. 고밀도의석회화는병변의구별을어렵게만들며, MDCT 에서혈관내경이좁게나타나혈관직경을과소평가하게된다. Kuettner 등 10) 은 MDCT 에서 Agatston score 로 335 이상의칼슘 score 는분석하기힘들다고제시했다. 우리연구에서는칼슘점수 300 이상의영상은대상에서제외시켰지만 11분절에서는칼슘으로인한인공물이있었다. 또한여러연구에서제시하는 MDCT 에서분석가능한최소직경은 2 mm 로이보다작은직경의곁가지혈관은 MDCT 에서평가하기에부적절하다. 이러한점은향후 64 slice MDCT 가보편화되면어느정도개선될수있을것이다. 본연구결과에서 MDCT 의음성예측도는위치별로나누었을때나혈관별로나누었을때나 98% 로높았다. 이는 MDCT 의역할을제시하는것으로관상동맥협착증이없는환자의진단에있어서유용할것으로생각된다. 칼슘점수와관상동맥의협착간에유의한상관관계를보여주는연구를했던 Herzog 등 15) 은비전형적인흉통을호소하는환자에서 MDCT 의진단적유용성을제시하였다. MDCT 의음성예측도가높기때문에전통적인관상동맥조영술과관상동맥성형술전에 screening하는진단방법으로써의가치가대두되는것이다. 또한관상 1171

6 동맥우회술후의협착이나관상동맥기형을평가하는데유용하게사용될수있을것이다. 13)16) 그러나관동맥중재술후의 stent 협착정도를평가하는데는금속으로인한인공물때문에현재는부적절하며, 향후기술적인발전이기대된다. 17) 결론적으로본연구결과심장박동수의조절과향상된 16 slice MDCT 를사용함으로써전체관상동맥분절중 84% 에서 MDCT 로분석가능한영상을얻을수있었으며, 관상동맥조영술결과와비교하였을때도높은정확성을보였다. 비침습적인 MDCT 를통해서도관상동맥협착증을진단할수있는가능성을제시하는것이다. 요약 배경및목적 : 침습적인관상동맥조영술을대신하여비침습적인방법으로소개된 MDCT 를이용하여 CT 혈관조영술 (MD- CT) 의민감도와진단의정확도를알아보고자하였다. 방법 : 허혈성심질환으로전통적인관상동맥조영술시행예정인환자 43명을대상으로 MDCT 와전통적인관상동맥조영술을 2일간격으로시행하였고모든환자에서베타차단제를이용하여 65 회이하의심장박동수를유지했다. 관상동맥조영술의결과를기준으로하여 MDCT 의민감도, 특이도, 진단적정확도를측정했다. 결과 : 43 명의환자의총 645 개의분절중 84% 에서 MDCT 로분석가능한영상을얻을수있었다. 관상동맥조영술결과총 44개관상동맥분절의협착에서 MDCT 의진단정확도는평균민감도 77%, 평균특이도 97%, 평균정확도 95% 였다. 각관상동맥별정확도는좌전하행지, 우관상동맥, 좌회선지가각각 95%, 98%, 95% 로우관상동맥의민감도가다른연구에비해높았다. 근위부동맥, 원위부동맥으로나누었을때각각의민감도는 100%, 65% 로근위부동맥에서높았다. 위양성의결과가 15분절에서있었는데이는관상동맥의석회화와혈관직경이작은경우에서였다. 결론 : 본연구에서는심장박동수의조절과향상된 16 slice MDCT 를사용함으로써전체관상동맥분절중 84% 에서 MDCT 로분석가능한영상을얻을수있었으며, 관 1172 상동맥조영술결과와비교하였을때도높은정확성을보였다. 이는비침습적인 MDCT 를통해서도관상동맥협착증을진단할수있는가능성을제시하는것이다. 중심단어 : 관상동맥조영술 ; 관동맥협착 ; 관상동맥질환. REFERENCES 1) Ohnesorge B, Flohr T, Becker C, Kopp AF, Schoepf UJ, Baum U, Knez A, Klingenbeck-Regn K, Reiser MF. Cardiac imaging by means of electrocardiographically gated multisection spiral CT: Initial experience. Radiology 2000; 217: ) Klingenbeck-Regn K, Schaller S, Flohr T, Ohnesorge B, Kopp AF, Baum U. Subsecond multi-slice computed tomography: basic and application. Eur J Radiol 1999;31: ) Becker CR, Ohnesorge B, Schoepf UJ, Reiser MF. Current development of cardiac imaging with multidetector-row CT. Eur J Radiol 2000;36: ) Nieman K, Oudkerk M, Rensing BJ, van Ooijen P, Munne A, van Geuns RJ, Feyter PJ. Coronary angiography with multislice computed tomography. Lancet 2001;357: ) Achenbach S, Giesler T, Roper D, Ulzheimer S, Derlien H, Schulte C, Wenkel E, Moshage W, Bautz W, Daniel WG, Kalender WA, Baum U. Detection of coronary artery stenoses by contrast-enhanced, retrospectively electroardiographically-gated, multislice spiral computed tomography. Circulation 2001;103: ) Schroeder S, Kopp AF, Kuettner A, Burgstahler C, Herdeg C, Heuschmid M, Baumbach A, Claussen CD, Karsch KR, Seipel L. Influence of heart rate in vessel visibility in noninvasive coronary angiography using new multislice computed tomography: experience in 94 patients. Clin Imaging 2002; 26: ) Nieman K, Rensing BJ, van Geuns RJ, Vos J, Pattynama PM, Krestin GP, Serruys PW, de Feyter PJ. Non-invasive coronary angiography with multislice spiral computed tomography: impact of heart rate. Heart 2002;88: ) Ropers D, Baum U, Pohle K, Anders K, Ulzheimer S, Ohnesorge B, Schlundt C, Bautz W, Daniel WG, Achenbach S. Detection of coronary artery stenoses wih thin-slice multidetector row spiral computed tomography and multiplanar reconstruction. Circulation 2003;107: ) Nieman K, Cademartiri F, Lemos PA, Raaijmakers R, Pattynama P, de Feyter PJ. Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography. Circulation 2002;106: ) Kuettner A, Kopp AF, Schroeder S, Rieger T, Brunn J, Meisner C, Heuschmid M, Trabold T, Burgstahler C, Martensen J, Schoebel W, Selbmann HK, Claussen CD. Diagnostic accuracy of multidetector computed tomography coronary angiography in patients with angiographically proven coronary artery disease. J Am Coll Cardiol 2004;43: ) Kopp AF, Schroeder S, Kuettner A, Baumbach A, Georg C, Kuzo R, Heuschmid M, Ohnesorge B, Karsch KR, Claussen CD. Non-invasive coronary angiography with high resolution multidetector-row computed tomography: results in 102 patients. Eur Heart J 2002;23: ) Kopp AF. Angio-CT: heart and coronary arteries. Eur J Korean Circulation J 2004;34(12):

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127~133특집_서준범 Focused Issue of This Month ssessment of Coronary rtery ypass Graft Patency Using Multidetector Computed Tomography Joon eom Seo, MD Department of Radiology, University of Ulsan College of Medicine Email