Original ORIGINAL Article ARTICLE Korean Circulation J 2006;36:308-317 ISSN 1738-5520 c 2006, The Korean Society of Circulation 관류결손의정도가게이트심근관류 SPECT 에서구한좌심실용적및구혈률의측정에미치는영향 경북대학교의과대학내과학교실, 1 핵의학교실 2 이장훈 1 채성철 1 류현민 1 배명환 1 이순학 1 양동헌 1 안병철 2 박헌식 1 조용근 1 이재태 2 전재은 1 박의현 1 Influences of Perfusion Defect on the Measurement of Left Ventricular Ejection Fraction and Volumes in Gated Myocardial Perfusion SPECT Jang Hoon Lee, MD 1, Shung Chull Chae, MD 1, Hyeon Min Ryu, MD 1, Myung Whan Bae, MD 1, Soon Hak Lee, MD 1, Dong Heon Yang, MD 1, Byeong-Cheol Ahn, MD 2, Hun Sik Park, MD 1, Yong Keun Cho, MD 1, Jaetae Lee, MD 2, Jae Eun Jun, MD 1 and Wee Hyun Park, MD 1 1 Department of Internal Medicine and 2 Nuclear Medicine, Kyungpook National University Hospital, Kyungpook National University Medical School, Daegu, Korea ABSTRACT Background and Objectives:The left ventricular ejection fraction (LVEF) and volume (LVV) are important variables in patients with coronary artery disease. Quantitative gated myocardial SPECT (QGS) permits the simultaneous assessment of perfusion, LVEF and LVV. However, the presence of a perfusion defect may influence the LVEF and LVV measured by QGS. Subjects and Methods:67 subjects (M/F=47/20; mean age:.2± 12.4 years) underwent both QGS with Tc-99m MIBI and 2-D echocardiography (Echo) at less than 7 days apart. The LVEF and LVV were measured by Echo, using the modified Simpson s method, and by QGS, using the automatic software, AutoQUANT TM. The QGS rest images were used to compare with the Echo. Results:The correlations between the QGS and Echo for LVEF, LVEDV and LVESV were good in all 67 subjects (r=0.781, 0.754 and 0.906, respectively, p<0.0001). In patients with no perfusion defect (n=34), the correlations between the QGS and Echo for LVEF, LVEDV and LVESV were good (r=0.689, 0.593 and 0.586, p<0.0001). In patients with a perfusion defect (n=33), the LVEF between the QGS and Echo was well correlated (r=0.777, p<0.0001), but the LVEF was higher by 7.1±8.7% from the Echo results. The LVEDV and LVESV by both QGS and Echo were also well correlated (r=0.804 and 0.929, respectively, p<0.0001), but the LVEDV and LVESV were higher from QGS by 17.9±34 and 16.9±25 ml, respectively. A Bland-Altman analysis showed the agreement between the QGS and Echo in patients without perfusion defect was better than for those with a perfusion defect. Conclusion:The perfusion defect from QGS might affect the measurements of the LVEF and LVV; therefore, the QGS and Echo values are not interchangeable. (Korean Circulation J 2006;36:308-317) KEY WORDS:Echocardiography;Tomography, emission-computed, single-photon;left ventricular function. 논문접수일 :2005 년 월 24 일수정논문접수일 :2006 년 1 월 11 일심사완료일 :2006 년 02 월 08 일교신저자 : 채성철, 700-721 대구광역시중구삼덕 2 가 50 번지경북대학교의과대학내과학교실전화 :(053) 420-5527 전송 :(053) 426-2046 E-mail:scchae@knu.ac.kr 308
Jang Hoon Lee, et al: Perfusion Defect in Gated Myocardial Perfusion SPECT 309 서 론 대상및방법 좌심실용적과구혈률은심장판막질환의치료, 경과관찰및예후판정, 1) 관상동맥질환 2) 과심부전환자의경과관찰에매우중요한정보를제공하는지표이고, 특히심근경색후일련의좌심실용적및좌심실구혈률의측정은좌심실의재형성 (remodeling) 3) 에관한중요한정보를제공하고치료효과를예측할수있다. 허혈성심장병에서심근의관류저하정도가증가할수록심장사건은증가하는것으로알려져있으며 4) 안정시좌심실구혈률은관상동맥질환환자의예후예측인자라고알려져있다. 5) 좌심실의용적과구혈률을측정하기위해이용되어온방법으로는좌심실조영술, 심초음파, 3차원자기공명영상이있으며, 핵의학적측정방법으로일회통과스캔, 게이트심장혈액풀스캔을이용한방법, 방사성동위원소혈관촬영술, 게이트심근관류 SPECT 등이있다. 심초음파검사는좌심실용적과구혈률측정에널리사용되어오는방법으로환자에게고통을주지않는비침습적검사이며, 방사능의피폭이없는간편한검사이다. 그러나심초음파검사는심초음파해상도가낮은경우, 시술자의경험및숙련도, 측정자체의오차등에따라정확도에제약이있고 6) 재현성이떨어진다 7) 고알려져있다. 게이트심근관류 SPECT 는심근관류상태에대한정보와동시에좌심실기능에대한정보를획득할수있게해준다. 8) Germano 등 9) 에의한 3차원영상을이용한소프트웨어의개발로영상을자동으로분석하여좌심실용적및구혈률을측정할수있게되어영상획득시간이짧아졌으며작업자에의한주관적영향을배제할수있고, 측정된검사결과는재현성이우수하여심초음파를비롯한다른심장검사법으로측정한결과들과상관성이좋은것으로알려져있다. -13) 본연구에서는게이트심근관류 SPECT 에서관류결손이있는경우좌심실의내막면을정확히설정하기어렵기때문에좌심실의용적및구혈률을구하는데오차가생길가능성이있다는가정을가지고이러한관류결손의유무또는관류결손의정도가좌심실용적및좌심실구혈률에미치는영향을좌심실내막을비교적용이하게구별할수있는심초음파검사로구한성적들과비교분석하였다. 게이트심근관류 SPECT 와심초음파로구한좌심실용적및구혈률이높은상관성을가진다는많은보고들이있으나, 14)15) 상관성이높은것이반드시일치율 (agreement) 이높다는것을의미하는것은아니다. 16) 또한이전연구에서환자군은관류결손의유무와정도에상관없이두값이비교되었으며, 제한된환자들에서비교분석이시행되었다. 본연구에서는관류결손의유무와크기가게이트심근관류 SPECT 로구한좌심실용적및구혈률측정에미치는영향을알아보기위하여심초음파로구한좌심실용적및구혈률과의상관성및일치율분석을시행하였다. 대상흉통을주소로경북대학교병원외래및응급실을방문하여운동부하또는약물부하게이트심근관류 SPECT 검사와심초음파검사를모두시행한 67명의환자를대상으로하였다. 두검사는최대 7일이내의간격을두고시행되었으며, 두검사사이에심장사건의발생이있었던경우는대상에서제외하였다. 방법게이트심근관류 SPECT 게이트심근관류 SPECT 는 1일검사법및 2일검사법으로영상을얻었으며, 분석에사용된자료는안정시영상에서얻은자료를이용하였다. 17) 1일검사법은안정시-부하시순서로영상을얻었으며, 안정시영상은안정시에 370 MBq ( mci) 의 Tc-99m MIBI 를정맥으로주사하고, 부하시영상은 1,0 MBq (30 mci) 의 Tc-99m MIBI 를정맥으로주사후저에너지고해상도평형조준기를장착한이중헤드감마카메라 (Vertex Plus, ADAC, USA) 를이용하여구하였다. 2일검사법은안정시와부하시각각 740 MBq (20 mci) 의 Tc- 99m MIBI 를정맥으로주사후 1일검사법과동일한방법으로영상을구하였다. 영상자료의획득은 20% 에너지창을 140 kev 을중심으로설정한후, 직각으로된두개의검출기를사용하여우전사위 45 부터좌후사위 45 까지 3 씩 180 회전시키면서 64 64 행렬로각 25초씩총 64개를투사영상을얻어컴퓨터에수록하였다. 게이트심근관류 SP- ECT 는심전도의 R-R 간격사이에 8 프레임으로시행하였으며, 심전도에서 R-R 간격이 50% 이내인경우만영상처리자료로이용하였다. 영상의재구성은 Butterworth 여과기를사용하여여과후역투사방법을이용하였으며, 6.56 mm 두께로심장의단축단면상, 수평장축단면상, 수직장축단면상을얻었다. 18) 관류결손의크기 (% extent), 정도 (summed stress score), 가역성 (summed difference score) 및좌심실구혈률은 Germano 등 9) 에의해개발된 AutoQUANT TM 소프트웨어를이용한자동화방법으로구하였으며, 안정시영상에서 1% 이상의관류결손을보이는경우관류결손이있는것으로판단하였다. 심초음파검사모든환자에서심초음파영상은 GE사의 VIVID7 을이용하여얻었으며, 숙련된두검사자에의해시행되었고, 검사자간의변이성 (variability) 은 2.6±2.1% 였다. 좌심실용적은이면성심초음파검사를이용하는것을원칙으로하여심첨 4방도 (apical 4 chamber view) 와심첨 2방도 (apical 2 chamber view) 에서구해서평균값을대표값으로하였다. 심
3 Korean Circulation J 2006;36:308-317 첨도 (apical view) 의경우에가능한한심내강이가장크게보이도록영상을기록함으로써 foreshortening 으로인한저평가를피하고, 심첨 4방도는초음파가좌심실측벽의중간부위를지나는단면을보이면서우심실이가장넓게보이는위치를취하였다. 19) 좌심실구혈률은 modified Simpson 방법을이용하였다. 해상도가가장좋은대표적인심장주기를선택하여저장후 continuous loop 로심첨 2방도및심첨 4 방도를재생하여좌심실변연을정하였으며, 좌심실이완기말심내막변연은심전도에서 QRS 파의시작점에서측정하였고, 좌심실수축기말심내막변연은심전도에서 T파의근처에서심내강이가장좁아지는시점에서측정후얻어진자료를 Simpson s 알고리듬에적용시켜좌심실구혈률을측정하였다. 통계처리통계적처리는 SPSS 프로그램 (11.5 version) 을사용하였 Table 1. Clinical characteristics of the subjects Number of subjects 67 Sex Male 47 (70.1%) Female 20 (29.9%) Age (years).2±12.4 Clinical diagnosis Myocardial infarction 19 (28.4%) Angina pectoris 31 (46.3%) Atypical chest pain 17 (25.4%) Risk factors Hypertension 33 (49.3%) Diabetes 12 (17.9%) Smoking 27 (40.3%) Hypercholesterolemia 36 (53.7%) Stress protocol One day 61 (91.0%) Two day 06 (09.0%) Adenosine 37 (55.2%) Exercise 30 (44.8%) 으며 Pearson 상관계수를이용한직선회귀분석법, paired sample t-test 를이용하였으며, p값이 0.05 미만인경우통계적으로유의한것으로판정하였다. 심초음파와게이트심근관류 SPECT 로얻어진자료의일치율을알아보기위해 Bland-Altman 도표를이용하여분석하였다. 결과 대상환자의임상적특성 (Table 1) 대상환자 67명의평균연령은.2±12.4 세, 남자가 47 명 (70.1%), 여자가 20명 (29.9%) 이었으며, 심근경색이 19명 (28.4%), 협심증이 31 명 (46.3%), 비전형흉통이 17 명 (25.4%) 이었다. 동반된위험인자로는고혈압을 33명 (49.3%), 당뇨병을 12명 (17.9%), 흡연을 27명 (40.3%), 고지혈증을 36명 (53.7%) 이가지고있었으며 28명 (41.8%) 의환자가관상동맥조영술을시행받았다. 61명 (91.0%) 의환자가 1일검사법을 6명 (9.0%) 의환자가 2일검사법을시행하였고, 37명 (55.2%) 의환자에게아데노신부하검사를시행하였고 30 명 (44.8%) 의환자에게운동부하검사를시행하였다. 관류결손유무에따른좌심실구혈률 (Table 2-4)(Fig. 1-3) 전체환자에서좌심실용적및구혈률비교전체 67명의환자에서심초음파로구한좌심실용적및구혈률과안정시게이트심근관류 SPECT 로구한좌심실용적및구혈률을비교분석하였다. 전체 67명의환자에서게이트심근관류 SPECT 로구한좌심실구혈률은심초음파로구한좌심실구혈률과유의한상관성이있었다 (r=0.781, p<0.0001). 그러나, 49명의환자에서게이트심근관류 SPECT 로구한좌심실구혈률이심초음파로구한좌심실구혈률보다낮게측정되었으며, 두값사이에는유의한차이가있었다 (55.3±12% 대 59.7±.4%, p<0.0001). 게이트심근관류 SPECT 로구한좌심실확장기말용적과심초음파로구한좌심실확장기말용적사이에는유의한상관성이있었으나 (r=0.754, p<0.0001), 게이트심 Table 2. Comparison of left ventricular parameters (EF, EDV, ESV) between gated myocardial SPECT and two-dimensional echocardiography in the patients without or with perfusion defect Gated myocardial SPECT 2D-Echo p* Correlation Total (n=67) E F (%) 55.3±12.0 59.7±.4 <0.001 r=0.781 EDV (ml) 98.4±43.7 90.1±27.9 <0.001 r=0.754 ESV (Ml) 47.2±39.3 37.7±24.1 <0.029 r=0.906 Patients without perfusion defect E F (%) 61.2±6.61 62.9±6.41 <0.061 r=0.689 (n=34) EDV(mL) 84.7±24.1 85.5±20.8 <0.839 r=0.593 ESV (Ml) 34.2±13.2 31.7±.0 <0.2 r=0.586 Patients with perfusion defect E F(%) 49.3±13.3 56.4±12.7 <0.001 r=0.777 (n=33) EDV (ml) 113.0±54.61 95.0±33.6 <0.007 r=0.804 ESV (Ml) 61.2±51.9 44.2±32.1 <0.001 r=0.929 *: p for the difference between two studies, : p<0.0001. Echo: echocardiography, EF: ejection fraction, EDV: end diastolic volume, ESV: end systolic volume, SPECT: single photon emission computed tomography
Jang Hoon Lee, et al: Perfusion Defect in Gated Myocardial Perfusion SPECT 311 Table 3. Agreement of left ventricular parameters (EF, EDV, ESV) between gated myocardial SPECT and two-dimensional echocardiography in the patients without or with perfusion defect Total (n=67) Patients without perfusion defect (n=34) Patients with perfusion defect (n=33) EF Echo EF-SPECT EF (%) 4.3±7.6. 1.7±5.2 7.1±8.7 Limits of agreement (%) -.8 to19.5-8.7 to 12.1 -.3 to 24.5 Average limits of agreement (%) 15.2.4 17.4 EDV Echo EDV-SPECT EDV (ml) -8.2±30.0.6±20.2-17.9±34.0. Limits of agreement (ml) -68.2 to 51.8-39.8 to 41.1-86.0 to 50.1 Average limits of agreement (ml).0 40.4 68.1 ESV Echo ESV-SPECT ESV (ml) -9.3±20.1-2.4±.8-16.9±25.0. Limits of agreement (ml) -49.6 to 31.0-23.9 to 19.2-66.9 to 33.0 Average limits of agreement (ml) 40.3 21.6 50.0 Echo: echocardiography, EF: ejection fraction, EDV: end diastolic volume, ESV: end systolic volume, SPECT: single photon emission computed tomography Table 4. Differences of left ventricular parameters (EF, EDV, ESV) between gated myocardial SPECT and two-dimensional echocardiography according to perfusion defect Perfusion defect (%) (Gated myocardial SPECT EF-2D Echo EF)/average EF (Gated myocardial SPECT EDV-2D Echo EDV)/average EDV (Gated myocardial SPECT ESV-2D Echo ESV)/average ESV 1-9% (n=17) -0.13±0.22 0.01±0.29 0.±0.41-19% (n=8) -0.14±0.13 0.22±0.23. 0.41±0.26 >20% (n=8) -0.15±0.13 0.36±0.13. 0.51±0.19. p=0.95 p=0.01 p=0.02 Echo: echocardiography, EF: ejection fraction, EDV: end diastolic volume, ESV: end systolic volume, SPECT: single photon emission computed tomography Patients without perfusion defect 35 90 Y=0.722X+15.771 r=0.689 25 SPECT EF (%) 70 50 30 Echo EF-SPECT EF (%) 15 5-5 -15 30 50 70 90-25 30 50 70 90 Echo EF (%) Patients with perfusion defect -35 35 (Echo EF+SPECT EF)/2 (%) 90 Y=0.814X+3.41 r=0.777 25 SPECT EF (%) 70 50 30 Echo EF-SPECT EF (%) 15 5-5 -15 30 50 70 90-25 A 30 50 70 90 Echo EF (%) B -35 (Echo EF+SPECT EF)/2 (%) Fig. 1. A: correlations of LVEF values measured by two-dimensional echocardiography (Echo EF) and gated myocardial perfusion SPECT (SPECT EF). B: Bland-Altman analysis for agreement between Echo EF and SPECT EF. EF: ejection fraction, LVEF: left ventricular ejection fraction, SPECT: single photon emission computed tomography.
312 Korean Circulation J 2006;36:308-317 Patients without perfusion defect 200 180 Y=0.69X+25.81 1 SPECT EDV (ml) 1 140 120 0 80 40 r=0.593 Echo EDV-SPECT EDV (ml) -40-90 0 50 0 150 200 20 0 0 50 0 150 200 Echo EDV (ml) Patients with perfusion defect 200-140 (Echo EDV+SPECT EDV)/2 (ml) 180 Y=1.306X-11.07 1 SPECT EDV (ml) 1 140 120 0 80 40 r=0.804 Echo EDV-SPECT EDV (ml) -40-90 0 50 0 150 200 20 A 0 0 50 0 150 200 Echo EDV (ml) -140 B (Echo EDV+SPECT EDV)/2 (ml) Fig. 2. A: correlations of LVEDV values measured by two-dimensional echocardiography (Echo EDV) and gated myocardial perfusion SPECT (SPECT EDV). B: Bland-Altman analysis for agreement between Echo EDV and SPECT EDV. EDV: end diastolic volume, LVEDV: left ventricular end diastolic volume. 근관류 SPECT 로구한좌심실확장기말용적이심초음파로구한좌심실확장기말용적보다높게측정되어두값사이에는유의한차이가있었다 (98.4±43.7 ml 대 90.1±27.9 ml, p=0.029). 좌심실수축기말용적은두검사간에높은상관성이있었으나 (r=0.906, p<0.0001), 두값사이에는유의한차이가있었다 (37.7±24.1 ml 대 47.2±39.3 ml, p< 0.0001). Bland-Altman 도표에서두검사간좌심실구혈률차이의평균값은 4.34±7.6%, 차이의표준편차의 2배는 15.2% 로전체환자의 94% 가포함되었다. 좌심실확장기말용적차이의평균값은 8.23±30 ml, 차이의표준편차의 2배는 ml로전체환자의 96.8% 가포함되었고, 좌심실수축기말용적차이의평균값은 9.3±20.1 ml, 차이의표준편차의 2 배는 40.28 ml로전체환자의 98.4% 가포함되었다. 관류결손이없는환자에서좌심실용적및구혈률비교안정시게이트심근관류 SPECT 에서관류결손이없는환자는 34명이었다. 게이트심근관류 SPECT 로구한좌심실구혈률은심초음파로구한좌심실구혈률과유의한상관성이있었으며 (r=0.689, p<0.0001), 두검사의좌심실구혈률평 균값에는유의한차이가없었다 (62.9±6.4% 대 61.2±6.7%, p=0.064). 좌심실확장기말용적은두검사간좌심실확장기말용적에유의한상관성이있었으며 (r=0.593, p<0.0001), 두값사이에유의한차이는없었다 (84.7±24.1 ml 대 85.5 ±20.8 ml, p=0.839). 좌심실수축기말용적은두검사간에유의한상관성이있었으며 (r=0.586, p<0.0001), 두값사이에유의한차이는없었다 (34.2±13.2 ml 대 31.7± ml, p=0.21). Bland-Altman 도표에서두검사간좌심실구혈률차이의평균값은 1.7±5.2%, 차이의표준편차의 2배는.4% 로 34 명중 97.1% 가포함되었다. 좌심실확장기말용적차이의평균값은 0.63±20.2 ml, 차이의표준편차의 2배는 40.44 ml로전체환자의 96.9% 가포함되었고, 좌심실수축기말용적차이의평균값은 2.36±.7 ml, 차이의표준편차의 2배는 21.58 ml로전체환자의 93.9% 가포함되었다. 관류결손이있는환자에서좌심실용적및구혈률비교안정시게이트심근관류 SPECT 에서관류결손이있는환자는 33명이었으며, 관류결손의크기범위는최소 1% 에서최대 36% 로평균.75% 였다. 게이트심근관류 SPECT 로
Jang Hoon Lee, et al: Perfusion Defect in Gated Myocardial Perfusion SPECT 313 Patients without perfusion defect 140 90 SPECT ESV (ml) 120 0 80 40 Y=0.773X+9.698 r=0.586 Echo ESV-SPECT ESV (ml) 70 50 30 - -30-50 0 20 40 80 0 20-70 0 0 50 0 Echo ESV (ml) Patients with perfusion defect 140-90 90 (Echo ESV+SPECT ESV)/2 (ml) SPECT ESV (ml) 120 0 80 40 20 Y=1.496X-5.022 r=0.929 Echo ESV-SPECT ESV (ml) 70 50 30 - -30-50 -70 0 50 0 A 0 0 50 0 Echo EDV (ml) B -90 (Echo ESV+SPECT ESV)/2 (ml) Fig. 3. A: correlations of LVESV values measured by two-dimensional echocardiography (Echo ESV) and gated myocardial perfusion SPECT (SPECT ESV). B: Bland-Altman analysis for agreement between Echo ESV and SPECT ESV. ESV: end systolic volume, LVESV: left ventricular end systolic volume. 구한좌심실구혈률은심초음파로구한좌심실구혈률과유의한상관성이있었으나 (r=0.777, p<0.0001), 두검사의좌심실구혈률평균값에는유의한차이가있었다 (49.3±13.3% 대 56.4(12.7%, p<0.0001). 두검사간좌심실확장기말용적은유의한상관성이있었으나 (r=0.804, p<0.0001), 두값사이에는유의한차이가있었다 (113±54.6 ml 대 95±33.6 ml, p=0.007). 두검사간좌심실수축기말용적유의한상관성이있었으나 (r=0.929, p<0.0001), 두값사이에는유의한차이를보였다 (61.2±51.9 ml 대 44.2±32.1 ml, p= 0.001). 관류결손이있는환자를관류결손의정도에따라 1~9%, ~19%, 20% 이상의세그룹으로층화하여관류결손의정도가좌심실구혈률및좌심실용적에미치는영향에대해알아보았다 (Table 4). 좌심실구혈률의경우관류결손의정도가증가함에따라게이트심근관류 SPCET 와심초음파로구한좌심실구혈률의차이가증가하는경향을보였으나통계적으로유의한차이는없었다 (p=0.95). 좌심실확장기말용적및수축기말용적의경우관류결손의정도가증가함에따라두검사간의차이가증가하여통계적으로유의한차이를보였다 ( 각각 p=0.01, p=0.02). Bland-Altman 도표에서두검사간좌심실구혈률차이의평균값은 7.1±8.7%, 차이의표준편차의 2배는 17.4% 로 33 명중 93.9% 가포함되었다. 좌심실확장기말용적차이의평균값은 17.97±34 ml, 차이의표준편차의 2배는 68.06 ml로전체환자의 96.6% 가포함되었고, 좌심실수축기말용적차이의평균값은 16.93±49.9 ml, 차이의표준편차의 2배는 49.96 ml로전체환자의 96.6% 가포함되었다. 고찰 안정시게이트심근관류 SPECT 에서관류결손유무에따른좌심실용적및구혈률의차이를심초음파와비교분석하였을때전체환자에서게이트심근관류 SPECT 와심초음파는좌심실용적및구혈률측정에서높은상관성을보였으나, 게이트심근관류 SPECT 에서구한좌심실구혈률이심초음파에비해평균 4.3% 낮게측정되어평균값에는유의한차이를보였으며, 좌심실용적측정에있어서는게이트심근관류 SPECT 로구한좌심실확장기말및수축기말용적이심초음파에비해각각 8.3 ml, 9.4 ml 높게측정되어평균값에도유의한차이를보였다. 관류결손이없는환자에서는
314 Korean Circulation J 2006;36:308-317 두검사에서좌심실용적및구혈률에높은상관성및일치율을보였고평균값에도유의한차이가없었으나, 관류결손이있는환자에서는게이트심근관류 SPECT 로구한좌심실구혈률이심초음파에비해평균 7.1% 낮게측정되어평균값에서유의한차이를보였고, 좌심실용적측정에있어서는게이트심근관류 SPECT 로구한좌심실확장기말및수축기말용적이심초음파에비해각각평균 17.9 ml, 16.9 ml 높게측정되어유의한차이를보였다. Bland-Altman 도표에서두검사간의좌심실용적및구혈률의일치율도관류결손이있는환자가관류결손이없는환자에비해낮았다. 이렇게차이를보인이유로는게이트심근관류 SPECT 정량알고리듬의제한점을들수있다. 게이트심근관류 SP- ECT 에서관류결손이있는경우에는좌심실의내막을구별하기가어렵기때문에비교적좌심실내막을잘구별할수있는심초음파에비해좌심실의용적및구혈률을구하는데오차가생겼을가능성이있다. 본연구에서는 Germano 등 9) 에의해개발된 Cedars-Sinai QGS 소프트웨어인 Auto- QUANT TM 에서이용하는알고리듬인 Gaussian fit 법으로좌심실용적및구혈률을측정하였다. Gaussian fit 알고리듬은 3차원영상을이용하여게이트단축상의용량을정하고좌심근을분할하여 (segmentation) 좌심근의무게중심부위를자동으로정한후방사선을그려방사선의계수분포를정한후비대칭 Gaussian 곡선을이용하여계수분포에 fitting 을시행하고, Gaussian 분포의최대값위치를좌심근중심면 (midmyocardial surface) 으로정하고 Gaussian 분포의표준편차를이용하여심내막과심외막표면을정한후좌심실용적및구혈률을구하는방법이다. 게이트심근관류 SPECT 로얻은좌심실용적과구혈률은광범위한관류결손이있는경우에정확성이낮아지는것으로알려져있다. Germano 등 9) 은관류결손이있어육안적판독에서심근의방사능섭취가명확히보이지않더라고외삽 (extrapolation) 에의해심내막및심외막면은정확하게정해질수있다고보고하였다. 그러나 Manrique 등 20) 은안정시관류결손의크기가 20% 이상이고좌심실기능저하가있었던심근경색환자를대상으로한연구에서심근경색으로고정관류결손이있는부위에심근의두께가얇아지게되고이로인해역운동 (dyskinesia) 및부분체적효과가생겨좌심실확장기말용적이과잉평가되어방사선동위원소혈관촬영술에비해게이트심근관류 SPECT 에서좌심실구혈률이평균 5% 정도과소평가된다고보고하였다. 또한 King 등 21) 은자동화된정량화프로그램으로좌심실구혈률을측정할경우정상적인심근방사능계수값을가진경우좌심실구혈률을 3~7% 과잉평가하지만, 심근방사능섭취계수값이 50% 이상감소하는관류결손이있을경우좌심실구혈률이 9% 이상과소평가된다고보고하였다. 특히, 심장심첨-측벽 (apico-lateral wall) 에관류결손이있을경우수평장축영상에서는거의보이지않고수직장축영상에서는심 첨부방사능섭취계수가매우낮게측정되므로자동화된정량화프로그램으로심내막을인지하기어려워실제심근에대한영상을얻기어려워진다고알려져있다. 22) 따라서관류결손이커지게되는경우정량결과에영향을미칠수있으며, 23) 본연구에서사용된 AutoQUANT TM 프로그램과같은자동화된정량화프로그램을사용하는경우심내막의경계를추적하는알고리듬에제한점이있어좌심실용적및구혈률의정확한측정에영향이있을수있다. 21) 본연구에서도안정시게이트심근관류 SPECT 에서관류결손이있는경우에심초음파에비해좌심실구혈률은평균 7.1% 정도차이를보였으며, 좌심실확장기말및수축기말용적은각각평균 17.9 ml, 16.9 ml 정도차이를보였다. 본연구에서관류결손이있는 33명의환자중 5명의환자에서는오히려게이트심근관류 SPECT 에서심초음파보다좌심실구혈률이과잉평가되었다. 이들중 3명의경우다른환자들에비해좌심실수축기말용적이 25 ml 미만으로작았다. 일반적으로게이트심근관류 SPECT 로얻은좌심실용적과구혈률은좌심실의용적이매우작은경우심근의방사능이심실쪽으로번질수있어시스템흔들림 (blur) 이생기고심근의경계가왜곡되어좌심실의용적이과소평가되고좌심실구혈률이과잉평가될수있는것으로알려져있다. 특히이러한현상은좌심실용적이작은여자에게흔하며좌심실수축기말용적이 20 ml 24) 미만일때현저한것으로알려져있다. 또한심박주기를나누는프레임수에따라서도좌심실용적이나구혈률에차이가날수있다. Germano 등 9) 은 8 프레임게이트심근관류 SPECT 는 16 프레임에비해좌심실구혈률을평균 3.71% 과소평가한다고보고하였다. Kondo 등 25) 은 8 프레임게이트심근관류 SPECT 와좌심실조영술및자기공명영상에서측정한좌심실용적및구혈률을메타분석 (meta-analysis) 을통해비교한연구에서 8 프레임게이트심근관류 SPECT 가좌심실조영술에비해좌심실구혈률을평균 7.6%, 자기공명영상에비해 6.3% 과소평가한다고보고하였다. 그리고좌심실확장기말용적은좌심실조영술에비해 32 ml, 자기공명영상에비해 13 ml 차이가난다고보고하였다. 본연구에서는전체환자에서심전도게이트는 8 프레임으로시행하였고, 심초음파와비교시게이트심근관류 SPECT 가좌심실구혈률에서평균 4.3%, 좌심실확장기말및수축기말용적에서각각평균 8.3 ml, 9.4 ml 차이를보였다. 다른원인으로는게이트심근관류 SPECT 와이면성심초음파의좌심실용적및구혈률을측정하는알고리듬의자체의차이를생각해볼수있다. Nichols 등 13) 은게이트심근관류 SPECT 에서 3가지다른알고리듬 (threshold 알고리듬, 26) Gaussian fit 알고리듬, Cardiac toolbox 알고리듬 ) 을이용하여좌심실용적및구혈률을구하고이를 modified Simpson 방법을이용한심초음파와측정값을비교하였다. 이
Jang Hoon Lee, et al: Perfusion Defect in Gated Myocardial Perfusion SPECT 315 연구에서좌심실구혈률은게이트심근관류 SPECT 의알고리듬에상관없이 3가지알고리듬모두에서심초음파와높은상관성및일치율을보였다. 그러나, 좌심실용적측정에서는 3가지알고리듬모두높은상관성은보였으나 modified Simpson 알고리듬과유사한 threshold 알고리듬을이용한경우에는심초음파와높은일치율을보인데비해 Gaussian fit 알고리듬의경우심초음파에비해좌심실용적을과잉평가한다고보고하여서본연구에부합하는결과를보였다. Lum 등 27) 도 Gaussian fit 알고리듬의 QGS, 4D-MSPECT 그리고 Cardiac toolbox 알고리듬의 ECT 등 3가지다른알고리듬의자동화된정량화프로그램으로좌심실구혈률및확장기말용적을비교한연구에서관류결손이있는환자에서 3가지알고리듬모두높은상관성을보였으나측정치는 Gaussian fit 알고리듬의 QGS가 4D-MSPECT 에비해좌심실구혈률은평균 4.2%, 좌심실확장기말용적은평균 16.6 ml 과소평가하였고, ECT 에비해서는좌심실구혈률을평균 4.9%, 좌심실확장기말용적은평균.3 ml 과소평가한다고보고하여서사용된분석소프트웨어에따라정량적지표는상이한값을보였다. 그외에도게이트심근관류 SPECT 로좌심실용적및구혈률측정시부정맥으로심전도이상이있는경우정확한게이팅이어려워게이트법적용시정량적지표의정확성이낮아질수있고, 28) 심실내동맥류가있는경우에도정확한좌심실기능을나타내지못하는것으로알려져있다. 또한재구성시이용된필터의종류, 좌심근의방사능계수정도에따라서도좌심실용적이나구혈률에차이가날수있다. 본연구에서는좌심실용적과구혈률측정의표준검사 (gold standard) 로알려진방사선동위원소혈관촬영술을시행하지않았다. 그리고, 심초음파로좌심실용적및구혈률을구하는방법으로 modified Simpson 방법을이용하였다. Folland 등 29) 은심초음파로좌심실용적및구혈률을구하는방법중 modified Simpson 방법이방사선동위원소혈관촬영술로구한좌심실용적및구혈률과가장상관관계가높다고보고하였다. Wahr 등 30) 도 modified Simpson 방법이심초음파로좌심실용적및구혈률을측정하는다른방법에비해재현성이우수하고검사자간차이도가장작다고보고하여서게이트심근관류 SPECT 로구한좌심실용적및구혈률을 modified Simpson 방법을이용한심초음파의성적과비교하는것은타당성을인정받을수있다고생각된다. 다만, 본연구에서방사선동위원소혈관촬영술과같은표준검사를시행하지않았기때문에두검사기법을비교시어느검사기법이정확도가높고우수하다고말하기에는제한점이있다고생각된다. 결론적으로, 게이트심근관류 SPECT 로구한좌심실용적및구혈률은심초음파로구한좌심실용적및구혈률과좋은상관성을보였으나게이트심근관류 SPECT 에서관류결 손이있는경우두검사의측정치에는유의한차이를보였으며, 관류결손이없는환자에비해좌심실용적및구혈률모두에서일치율도낮았다. 따라서관류결손이있는관상동맥질환환자에서좌심실기능지표로치료반응및예후, 임상적경과를확인할경우동일한검사기법으로추적검사를시행해야하며다른검사기법을시행한경우측정치를그대로받아들이기위해서는환자의임상적변수및검사기법의특성을고려한해석이필요한것으로생각된다. 요약 배경및목적 : 좌심실용적및구혈률은관상동맥질환환자의치료, 예후예측및경과관찰에매우중요한기능지표이다. 현재게이트심근관류 SPECT 를이용하여심근관류이상을진단하는동시에좌심실용적및구혈률을측정하는방법이많이사용되고있다. 저자는게이트심근관류 SPECT 에서관류결손이있는경우에는좌심실의내막면을정확히설정하기어렵기때문에좌심실의용적및구혈률을구하는데오차가생길가능성이있다는가정을가지고이러한관류결손의유무또는관류결손의정도가좌심실용적및좌심실구혈률에미치는영향을좌심실내막을비교적용이하게구별할수있는심초음파검사로구한성적들과비교분석하였다. 방법 : 운동또는약물부하게이트심근관류 SPECT 를시행한환자중심초음파검사를함께시행한 67명의환자 ( 남 / 여 =47/ 20; 평균연령 :.2±12.4 세 ) 를대상으로하였다. 게이트심근관류 SPECT 에서좌심실용적및구혈률측정은 Gaussian fit 알고리듬을이용한 AutoQUANT TM 프로그램을사용하였고심초음파를이용한좌심실용적및구혈률측정은 modified Simpson 방법을사용하였다. 결과 : 전체 67명의환자에서게이트심근관류 SPECT 와심초음파는좌심실구혈률, 좌심실확장기말용적및수축기말용적측정에서높은상관성 (r=0.781, r=0.754, r=0.906, p< 0.0001) 을보였으나게이트심근관류 SPECT 에서구한좌심실구혈률이심초음파에비해평균 4.34±7.6% 낮게측정되었고, 좌심실확장기말및수축기말용적측정에있어서는게이트심근관류 SPECT 에서심초음파에비해각각평균 8.3±29.2 ml, 9.4±20.2 ml 높게측정되어유의한차이를보였다. 관류결손이없는 34명의환자에서는두검사에서좌심실구혈률, 좌심실확장기말및수축기말용적에높은상관성 (r=0.689, r=0.593, r=0.586, p<0.0001) 을보였고평균값에도유의한차이가없었으나, 관류결손이있는 33명의환자에서는두검사간에높은상관성 (r=0.777, p<0.0001) 은있었으나게이트심근관류 SPECT 로구한좌
316 Korean Circulation J 2006;36:308-317 심실구혈률이심초음파에비해평균 7.1±8.7% 낮게측정되었고, 좌심실확장기말및수축기말용적측정에있어서게이트심근관류 SPECT 와심초음파검사사이에높은상관성 (r=0.804, r=0.929, p<0.0001) 을보였으나게이트심근관류 SPECT 에서심초음파에비해좌심실확장기말용적은평균 17.9±34 ml, 좌심실수축기말용적은평균 16.93 ±25 ml 높게측정되어유의한차이를보였다. Bland-Altman 도표에서관류결손이있는환자에서관류결손이없는환자에비해두검사간좌심실용적및구혈률값의일치율이낮았다. 결론 : 게이트심근관류 SPECT 로구한좌심실용적및구혈률과심초음파로구한좌심실용적및구혈률사이에는유의한상관성이있었으나, 관류결손이있는경우둘사이에는유의한차이가있어서측정치를그대로받아들이기위해서는환자의임상적변수및검사기법의특성을고려한해석이필요하다. 중심단어 : 심초음파 ; 심근 SPECT; 좌심실기능. REFERENCES 1) Bonow RO, Lakatos E, Maron BJ, Epstein SE. Serial long-term assessment of the natural history of asymptomatic patients with chronic aortic regurgitation and normal left ventricular systolic function. Circulation 1991;84:1625-35. 2) Pilote L, Silberberg J, Lisbona R, Sniderman A. Prognosis in patients with low left ventricular ejection fraction after myocardial infarction: importance of exercise capacity. Circulation 1989;80:1636-41. 3) Garot P, Pascal O, Simon M, et al. 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