99Tcm-MIBI与18F-FDG双核素同时采集法心肌显像检测存活心肌

目的 评价辨99Tcm-甲氧基异丁基异腈(MIBI)与18F-脱氧葡萄糖(FDG)双核素同时采集法心肌显像(DISA SPECT)检测存活心肌的临床价值.方法 21例经彩超检查证实存在左室壁节段运动障碍的冠心病患者,进行DISA SPECT、冠状动脉造影(CAG)及经皮冠状动脉介人治疗(PCI),对所有狭窄病变行完全血运重建术.参照美国超声心动图学会16节段划分法获得心肌各运动异常节段DISA SPECT图像,并对心肌存活情况进行判定.DISA SPECT图像用目测半定量法分析.术后1,3和6个月时复查心脏超声,以冠状动脉血运重建后室壁节段收缩功能改善为判断存活心肌的"金标准",根据诊断试验四格表评价DISA SPECT检测存活心肌的价值.结果 21例冠心病患者共获得符合条件的室壁运动异常节段156个,根据"金标准"判断其中105个为存活心肌,51个为非存活心肌,DISA SPECT检测存活心肌的灵敏度、特异性、阳性预测值、阴性预测值、准确性分别是93.3%(98/105)、82.4%(42/51)、91.6%(98/107)、85.7%(42/49)、89.7%(140/156).结论 DISASPECT目测半定量法检测存活心肌有较高的临床价值.     

^201Tl与^13N—NH3、^18F—PDG PET心肌显像判断存活心肌的对比研究

目的 比较再注射^201Tl心肌显像与联合应用^13N-NH3及^18F-脱氧葡萄糖（FDG）心肌PET显像判断存活心肌的临床价值。方法 20例心肌梗死患者，行^201Tl SPECT负荷、再分布、再注射显像及^13N-NH3`^18F-FDG PET心肌显像。将左室分成9个节段，以视觉评价法对放射性分布进行4级评分。获得^201Tl SPECT再分布、再注射像及^18F-FDG PET显像的局部心肌摄取率（％ID）。结果 PET判定为存活心肌的48个节段中，45个节段（93．8％）^201Tl再注射像也判定为存活心肌。在^201Tl再分布像示放射性分布严重低下的24个节段，^201Tl再注射像与PET显像判定存活心肌的一致率为87．5％，其中37．5％为存活心肌节段，50％为地存活心肌节段。2种显像方法的％ID无明显差异，且呈显著正相关（r=0.722)。结论 再注射^201Tl心肌显像判断存活心肌的准确性与PET心肌显像相似，有较大的临床应用价值。     

特发性扩张型心肌病合并甲状腺功能减退加重心肌损伤的影像学评价

目的通过^99Tcm-MIBI心肌灌注SPECT／^18F—FDG心肌代谢PET显像和心脏MRI延迟增强成像（cMRI—LGE）,探讨特发性扩张型心肌病（IDC）合并甲状腺功能减退（简称甲减）与心肌损伤的关系。方法2010年10月至2012年12月诊断为IDC的连续病例63例[男42例,女21例,平均年龄（52±11）岁]入选,患者均进行血浆TT3、TT4、FT3、FT4和TSH全自动化学发光免疫法测定、^99Tcm-MIBI心肌灌注SPECT／^18F—FDG心肌代谢PET显像和cMRI—LGE。利用标准17节段模型进行心肌节段分析,灌注／代谢图像分成4种类型：正常灌注／代谢、灌注／代谢不匹配、灌注／代谢轻中度匹配、灌注／代谢完全匹配;cMRI-LGE图像分为无延迟强化、壁间强化和透壁强化。通过x^2检验进行分组数据的比较。结果根据所测血浆激素水平,患者被分成甲状腺功能（简称甲功）正常组（53例）和甲减组（10例）。甲功正常组正常灌注／代谢的心肌节段数所占的比例明显高于甲减组：71.8％（647／901）和57．6％（98／170）,x^2=13．50,P〈0．001;而灌注／代谢不匹配的心肌节段比例则低于甲减组：17．8％（160／901）和31．2％（53／170）x^2=16．20,P〈0．001。甲功正常组cMRI—LGE无延迟强化的心肌节段比例明显高于甲减组,分别为88．0％（793／901）和69．4％（118／170）,x^2=35．70,P〈0．001;但壁间强化的心肌节段比例则低于甲减组,分别为4．8％（43／901）和24．1％（41／170）,x^2=74．70,P〈0．001。结论^99Tc^m-MIBI心肌灌注SPECT／^18F—FDG心肌代谢PET显像和cMRI—LGE证实甲减能够加重IDC患者的心肌损伤。SPECT／PET可以检测出更多的慢性缺血／存活心肌,而cMRI-LGE可以检测出更多的心肌纤维化病变,两者结合能提供更全面的心肌损伤信息。     

双嘧达莫负荷心肌^201Tl SPECT显像用于缺血型成人病毒性心肌炎的价值

目的观察根据心电图等临床疑诊为成人病毒性心肌炎心肌缺血型患者的双嘧达莫负荷心肌^201Tl SPECT显像的表现。方法选取根据排除法临床疑诊为病毒性心肌炎后遗症——心肌缺血型患者79例,年龄19～55岁。按体质量0．56mg／kg给予双嘧达莫,于4min内静脉注射,2min后注射^201Tl,注完后10及240min分别进行双嘧达莫负荷心肌^201Tl SPECT显像,原始图像经三维重建后由2位以上有经验的核医学科医师进行分析。不同性别组间显像结果比较行χ^2检验,经SAS8．1软件处理。结果在有ST—T改变的79例患者中,所有患者双嘧达莫负荷^201Tl图像（10min）均显示左心室心肌放射性分布正常,延迟（240min）显像时有34例（43．04％）患者（包括正常共272个节段）出现部分心肌节段反向放射性分布稀疏或缺损,即“反向再分布”,共累及36个节段：前壁9个（25．00％）、下壁11个（30．56％）、前间壁8个（22．22％）、前侧壁4个（11．11％）、心尖部4个（11．11％）;其中单个节段受累32例（94．12％）,2个节段受累2例（5．88％）。79例中其余45例（56．96％）患者延迟显像则为放射性分布正常。有70．83％（17／24）的男性和30．91％（17／55）的女性患者延迟显像出现“反向再分布”,不同性别间差异有统计学意义（χ^2=10．86,P〈0．01）。结论双嘧达莫负荷心肌^201Tl SPECT显像对指导缺血型心肌炎诊治有益,另外对有ST-T改变的女性患者诊断需慎重考虑。     

双核素心肌SPECT显像与PET显像检测存活心肌的对比研究

目的评价99Tcm-甲氧基异丁基异腈(MIBI)/18F-脱氧葡萄糖(FDG)双核素同时采集法(DISA)SPECT显像检测存活心肌的价值。方法对75例冠心病陈旧性心肌梗死患者进行了研究。采用双探头SPECT仪配备超高能准直器,行DISASPECT显像,同时行18F-FDGPET显像,用半定量法分析图像。结果75例患者中,99Tcm-MIBI心肌灌注显像有222个节段灌注减低,而DISA法FDG-SPECT显像有118个节段(53%)改善,FDG-PET显像有128个节段(58%)改善,即灌注/代谢不匹配,以存活心肌为主。DISA法FDG-SPECT有104个节段灌注/代谢匹配,FDG-PET显像有94个节段灌注/代谢匹配,为坏死心肌。FDG-SPECT与FDG-PET对存活心肌的检出率差异无显著性(χ2=0.863,P>0.05)。222个心肌灌注减低节段的FDG-SPECT与FDG-PET的得分符合率为91%。结论DISA法SPECT显像方法简便,费用较低,对检测存活心肌有重要价值。     

硝酸甘油介入99Tcm-tetrofosmin SPECT与18F-FDG PET显像评估心肌活力比较

目的 比较硝酸甘油介入^99Tc^m-tetrofosmin SPECT心肌血流灌注显像与^18F-FDG PET心肌代谢显像评估心肌活力的价值。方法 既往有心肌梗死史伴左心功能不全经冠状动脉造影确诊为冠心病的患者36例，行二日法静息和硝酸甘油介入^99Tc^m-tetrofosmin SPECT显像，并在1周内再行^18F-FDG PET心肌代谢显像及静息超声心动图检查。将左心室分成13个节段，分析超声心动图室壁运动，并分析相同节段^99Tc^m-tetrofosmin与^18F-FDG的相对摄取比值，以^18Tc^m-tetrofosmin摄取比值55％，^18F—FDG摄取比值50％为判断心肌活力有无的阈值。以k统计比较3种方法的一致性。结果 超声心动图示131个节段呈无运动或反向运动。^99Tc^m-tetrofosmin静息显像示其中78个节段（60％）心肌有活力，53个节段（40％）无活力。该53个节段中14个（26％）在硝酸甘油介入后可见再填充，余39个节段无改变。在^18F—FDGPET显像中，硝酸甘油介入显像再填充节段的心肌放射性摄取明显增高。再填充节段与无填充节段比较，心肌FDG摄取分别为（76±15）％和（58±17）％，差异有统计学意义（P〈0．01）。硝酸甘油介入显像中，92个心肌节段（70％）有活力，39个无活力。tetrofosmin静息显像评估心肌活力与FDG PET显像比较，k值为0．35，而硝酸甘油介入^99Tc^m-tetrofosmin SPECT与^18F—FDGPET显像结果比较，k值为0．53。结论 硝酸甘油介入^99Tc^m-tetrofosmin SPECT显像可提高对心肌活力的检测能力，与^18F—FDG PET心肌代谢显像有很好的一致性。     

双核素心肌灌注-代谢显像评价存活心肌对心肌梗死患者择期血运重建术后左心功能的影响

目的采用^99Tc^m-MIBI加^18F-FDG双核素心肌灌注-代谢显像（DISA）评价冠心病心肌梗死患者有无存活心肌,以判断择期血运重建后存活心肌对左心功能的影响。方法选择确诊心肌梗死患者91例,行DISA。根据超声心动图（UCG）结果将患者分为心功能不全（A组）和心功能正常（B组）2组,在行PCI术后1,3和6个月观察UCG结果。采用SPSS13．0软件进行统计学处理,2组间均值比较采用t检验,率的比较采用,检验。结果A组灌注平均缺损（9．8±3．5）个节段,B组灌注平均缺损（5．4±2．6）个节段;2组相比,t=6．87,P〈0．01。A组代谢平均缺损（7．5±3．4）个节段,B组代谢平均缺损（4．6±2．8）个节段,2组相比,t=4．46,P〈0．01。A组检出存活心肌173个节段,占37．8％（173／458）,B组检出188个节段,占61．2％（188／307）,2组相比,x2=40．61,P〈0．001。A组灌注显像总评分（SPS）为（Z8．43±11．86）分,代谢显像总评分（SMS）为（20.17±8．52）分,（代谢-灌注）总评分之差（SDS）为（0．39±3．17）分;B组SPS为（21．36±9．54）分,SMS为（15．19±5．74）分,SDS为（-12．72±4．55）分,2组相比,t=3．15,3．32和15．59,P均〈0．01。A组存活心肌≥4个节段的LVEF升高差值（ALVEF）为（12．81±2．62）％,明显高于B组的（5．90±1．91）％,t=16．33,P〈0．001;左心室舒张末期内径回缩差值（△LVEDd）为（-13．13±4．20）mm,也明显高于B组（-7．75±2．31）mm,t=6．86,P〈0．001;A组存活心肌〈4个节段的△LVEF和△LVEDd则明显低于B组,t=3．25和4．92,P均〈0．01。结论心肌梗死区是否有存活心肌及存活心肌节段数可能是择期血运重建后左心功能改善程度的重要影响因素。     

99Tcm-NOET门控心肌灌注SPECT评价冠心病的价值

目的评价99Tcm--双（N-乙氧基,N-乙基-二硫代氨基甲酸酯）氮化锝（99Tcm-NOET）静息门控断层心肌灌注显像对冠心病患者的诊断价值。方法疑诊为冠心病的45例患者注射925MBq 99Tcm-NOET后1h用SPECT行静息门控心肌灌注显像,获得舒张未期容积（EDV）、收缩未期容积（ESV）、左室射血分数（LVEF）等心功能参数和舒张末期容积灌注、局部射血分数、局部室壁活动和室壁增厚度4个靶心图。所有患者在1周内行冠状动脉造影,将冠状动脉狭窄≥50％定为病变血管。根据冠状动脉造影结果将其分为心肌梗死组、心肌缺血组和对照组三组。结果99Tcm-NOET静息门控SPECT诊断冠心病的灵敏度和特异度分别为68．42％和83．33％。心肌梗死组的心功能参数[EDV=（129．32±9．14）ml,ESV=（80．97±9．49）ml,LVEF=（40．15±3．28）％】与对照组【EDV=（80．91±3．12）ml,ESV=（30．12±1．79）ml,LVEF=（63．51±1．04）％]相比,统计学差异有显著性（EDV：F=22．103,ESV：F=32．277,LVEF：F=42．60：4,均为P〈0．01）,心肌缺血组的心功能参数[（EDV=（70．83±3．46）ml,ESV=（25．13±2．85）ml,LVEF=（65．55±2．62）％1与对照组相比,统计学差异无显著性意义。心肌梗死组左室心肌共分为460个节段,其中209个节段局部灌注、局部射血分数、局部室壁活动和室壁增厚度4个靶心图均异常。局部灌注异常的节段共328个节段,伴有局部射血分数、局部室壁活动和室壁增厚度异常分别有250个、240个和276个节段。局部灌注异常的节段与局部射血分数、局部室壁活动和室壁增厚度异常的节段不完全匹配。结论99Tcm-NOET静息门控心肌灌注显像对冠心病的诊断有较大临床应用价值,所获得的整体心室功能参数在心肌梗死的评价中有优越性,但对心肌缺血的诊断价值不大。心肌梗死中存在有不少的局部灌注与心肌?     

缺血心肌动物模型PET和SPECT显像及组织学对比研究

目的评估^201TI SPECT及^18F-脱氧葡萄糖（FDG）PET显像对模型猪心肌活力的鉴别。方法健康家猪12头，其中10头于冠状动脉左旋支起始处放置Ameriod环，饲养28d形成慢性心肌缺血动物模型（另2头作正常对照），行^201TI SPECT心肌灌注显像和^18F—FDG PET心肌代谢显像并与HE染色病理学改变进行比较。结果81个心肌节段中，^18F—FDG心肌显像示心肌有活力的节段为73个（90．1％），明显高于^201TI心肌显像所示的62个（76．5％），差异有显著性（P〈0．05）。HE染色结果示有心肌活力的节段为74个（91．3％），与^18F—FDG心肌显像所示结果差异无显著性（P〉0．05）。结论^18F—FDGPET心肌显像检测心肌活力的准确性明显高于^201TI SPECT心肌显像。     

99mTc-MIBI延迟心肌断层显像评估存活心肌的初步临床研究

目的评价４小时９９ｍＴｃ甲氧基异丁基异腈（ＭＩＢＩ）延迟显像在评估心肌活力方面的价值。方法对３０例冠心病（ＣＡＤ）病人（１８例经冠状动脉造影证实）进行常规静息和４小时延迟９９ｍＴｃＭＩＢＩ心肌断层显像。对其中１０例经冠状动脉血运重建术治疗的病人术后３５６±１９２天进行心肌断层显像随访。将左室心肌划分为９个节段。采用四点计分法对各节段核素分布进行半定量评价（摄取正常＝３，重度降低或缺损＝０）。结果３０例ＣＡＤ病人常规静息显像示１２６个（４６７％）节段核素分布异常，延迟显像示１０５个（３８９％）节段核素分布异常。常规静息显像心肌计分≤１（“无活力”）的节段有９３个；延迟显像时３６４％的０分节段和５３１％的１分节段计分改善≥１。延迟显像与冠状动脉血运重建术后显像对比，判断存活心肌的阳性预测值为８４２％，阴性预测值为９００％，预测准确率为８７２％，两者有良好的一致性（χ２＝２１５９，Ｐ＜００１）。结论９９ｍＴｃＭＩＢＩ延迟心肌显像，通过一次给药可较有效地克服静息心肌显像低估心肌活力的不足，对判定缺血心肌活力状态方面具有临床实用价值     

Low-dose dobutamine electrocardiograph-gated myocardial SPECT for identifying viable myocardium: comparison with dobutamine stress echocardiography and PET.

The identification of severely dysfunctional but viable myocardium is of particular importance for the selection of patients with depressed left ventricular function who will benefit from coronary revascularization. Assessment of inotropic reserve with dobutamine has recently been used for this purpose. This study compared the accuracy of low-dose dobutamine stress gated myocardial SPECT (DS SPECT) with the accuracy of dobutamine stress echocardiography (DSE) and resting perfusion SPECT for the identification of viable myocardium in patients with previous myocardial infarction. METHODS: Resting and low-dose dobutamine (7.5 microg/kg/min) gated (99m)Tc-tetrofosmin SPECT and echocardiography and resting (18)F-FDG PET were prospectively studied in 23 patients with previous myocardial infarction and severely depressed regional function. Twenty-one of them were successfully studied with each technique. The left ventricular wall was divided into 14 segments to assess wall motion using a 5-point scale. PET viability was defined as FDG uptake >/= 50% of the maximum uptake in a region with normal wall motion. For DS SPECT and DSE studies, viable myocardium was defined as hypokinetic areas with > or = 1 point improvement in wall motion. For resting perfusion SPECT, viable myocardium was defined as hypokinetic areas with a relative uptake > or = 50% of the maximum uptake. RESULTS: Of a total of 294 segments, 55 had severe resting dyskinesis. Thirty-four segments were identified as viable on FDG PET, and 21 segments were identified as nonviable. Eleven segments were inadequately visualized with DSE, including 5 segments in the apex. Sensitivities (78% vs. 76%) and specificities (94% vs. 100%) were similar for DSE and DS SPECT, with a concordance of 86% (kappa = 0.72). DS SPECT and perfusion SPECT did not significantly differ with respect to sensitivities (76% vs. 85%, respectively). However, specificity was significantly higher for DS SPECT than for perfusion SPECT (100% vs. 52%, respectively, P < 0.05). CONCLUSION: This study indicated that DS SPECT correlates well with DSE in the assessment of viability. In addition, gated SPECT can evaluate regional wall motion, even in areas inadequately assessed by echocardiography. DS SPECT may also provide additional information for identifying viable myocardium, which is often overestimated by routine perfusion scans.     

Pulsed Doppler tissue imaging for the assessment of myocardial viability: comparison with 99mTc sestamibi perfusion imaging

The aim of the present study was to examine whether Doppler tissue imaging demonstrated comparable diagnostic performance for the detection of viable myocardium compared to myocardial perfusion imaging with Tc hexakis-2-methoxyisobutylisonitrile (MIBI). We studied 30 patients with old myocardial infarction who underwent percutaneous transluminal coronary angioplasty (PTCA). Myocardial single photon emission computed tomography (SPECT) with Tc-MIBI and two-dimensional echocardiography were carried out within 7 days before PTCA. We measured regional Tc-MIBI uptake for each myocardial segment from SPECT and peak systolic velocity and a ratio of regional pre-ejection period to regional ejection time (PEP/ET) from pulsed Doppler tissue imaging. Biplane left ventriculography was performed before interventional procedures and repeated 3 months after PTCA. Myocardial viability was determined when wall motion was improved at least one grade after PTCA. The peak systolic velocity was positively correlated with regional Tc-MIBI uptake (R =0.59, P<0.01). The PEP/ET demonstrated inverse correlation with Tc-MIBI uptake ( R=-0.59, P<0.01). Peak systolic velocity of viable segments was higher than that of non-viable segments ( P<0.05). The PEP/ET was lower in viable segments than in non-viable segments ( P<0.05). Peak systolic velocity and PEP/ET demonstrated high diagnostic accuracy for detecting viable myocardium compared with Tc-MIBI perfusion imaging (80% and 79% vs 90%). These data indicate that measurements of regional peak systolic velocity and PEP/ET by Doppler tissue imaging are useful for evaluating myocardial viability quantitatively and provide helpful information for a clinical judgment in an interventional strategy.     

Selective intracoronary injection of sestamibi to detect myocardial viability: Prediction of perfusion and contractile recovery after percutaneous transluminal coronary angioplasty

BACKGROUND: The main limitation of myocardial single photon emission computed tomography (SPECT) in detecting hibernating myocardium is the poor delivery of radiotracers in hypoperfused areas supplied by severely stenotic coronary arteries. Increasing local availability of radiotracers by intracoronary injection might represent an attractive solution. The hypothesis that the intracoronary administration of sestamibi could improve myocardial SPECT accuracy in detecting hibernating myocardium was addressed in this pilot study. METHODS AND RESULTS: Seven patients with prior myocardial infarction and severe stenosis of the infarct-related artery underwent myocardial SPECT after intracoronary injection of technetium 99m sestamibi immediately before percutaneous transluminal coronary angioplasty (PTCA). Wall motion and perfusion were evaluated, before and 1 month after PTCA, by 2-dimensional echocardiography and rest-redistribution thallium 201 SPECT. A "low-flow area" was identified on the pre-PTCA Tl-201 SPECT image as the area with less than 50% of maximum radiotracer uptake. Changes in wall motion and perfusion in the low-flow area were compared with results of intracoronary sestamibi imaging. On a pixel-by-pixel analysis, intracoronary sestamibi predicted perfusion recovery within the low-flow area with a 91% sensitivity, a 78% specificity, and an 82% overall accuracy. Only in the 5 patients with an extent of sestamibi uptake greater than one third of the low-flow area was an improved regional and global left ventricular wall motion observed after PTCA (wall motion score index decreased from 1.95 +/- 0.28 to 1.60 +/- 0.34, P =.007; left ventricular ejection fraction increased from 42% +/- 7% to 49% +/- 7%, P =.001; asynergic segments in the low-flow area decreased from 3.6 +/- 0.9 to 1.8 +/- 1.5, P =.021). CONCLUSIONS: In patients with prior myocardial infarction and severe stenosis of the infarct-related artery, sestamibi uptake after intracoronary administration identified viable myocardium that was undetected after rest-redistribution thallium SPECT but capable of clinically significant contractile improvement after revascularization.     

Detecting myocardial salvage after primary PTCA: early myocardial contrast echocardiography versus delayed sestamibi perfusion imaging.

The extent of myocardial salvage after primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI) is variable and cannot be predicted on the basis of either vessel patency or early regional wall motion assessment. The aim of this study was to evaluate the reliability of microvascular integrity, as shown by myocardial contrast echocardiography (MCE), as an indicator of tissue salvage and a predictor of late functional recovery, and to compare MCE with the quantification of tracer activity in sestamibi perfusion imaging. METHODS: Twenty-six patients with AMI who received successful treatment with primary PTCA were examined with MCE during cardiac catheterization immediately before and after vessel recanalization. Myocardial contrast effect was scored as 0 (absent), 0.5 (partial) or 1 (normal). Wall motion was assessed by two-dimensional echocardiography on admission and 1 mo later with a 16-segment model and 4-point score. Resting sestamibi SPECT was collected within 1 wk after AMI. The risk area was defined by MCE as the sum of the segments with no perfusion (score 0) before PTCA. Myocardial viability was defined by MCE as an increase in contrast score in the same segments after PTCA and by sestamibi SPECT as a preserved tracer activity (>60% of peak activity). The functional recovery after 1 mo detected by two-dimensional echocardiography was the reference standard for viability. RESULTS: A total of 50 segments showed perfusion defects before PTCA (risk area). Immediately after PTCA, the MCE score increased in 44 of 50 segments, whereas sestamibi SPECT showed preserved activity in 22 of 50 segments. After 1 mo, the wall motion score decreased in 22 of 50 segments (viable segments) and was unchanged in the remaining 28 segments. Thus, MCE showed a sensitivity of 91% and a specificity of 14% in detecting viable myocardium, whereas sestamibi SPECT showed a lower sensitivity (68%) but a significantly higher specificity (75%; P < 0.00001). The positive predictive values were 45% and 68% for MCE and SPECT (P < 0.005), respectively, and the negative predictive values were 67% and 71%, respectively. On a patient basis, SPECT was more specific (79% versus 21%; P < 0.01) and showed a higher overall predictive accuracy (88% versus 50%; P < 0.01) than MCE. CONCLUSION: The demonstration of microvascular integrity by MCE performed immediately after primary PTCA has a limited diagnostic value in predicting salvaged myocardium. Conversely, tracer activity quantification in resting sestamibi SPECT performed in a later stage is confirmed to be a reliable approach for recognizing myocardial stunning and predicting functional recovery.     

Fatty acid imaging with 123I-15-(p-iodophenyl)-9-R,S-methylpentadecanoic acid in acute coronary syndrome.

123I-15-(p-iodophenyl)-9-R,S-methylpentadecanoic acid (9-MPA) has recently been developed as a tracer for myocardial fatty acid uptake. The aim of this study, which was performed as part of a phase III clinical trial of 9-MPA, was to test the usefulness of 9-MPA for the assessment of myocardial viability in patients with acute coronary syndrome (ACS). METHODS: Fifteen patients with ACS who had undergone direct percutaneous transluminal coronary angioplasty were examined. Myocardial SPECT with 9-MPA and 99mTc-sestamibi and low-dose dobutamine echocardiography were performed within 2 wk after onset. The 9-MPA images were obtained 10 and 60 min after tracer administration, and sestamibi imaging was begun 60 min after the injection. The left ventricle was divided into 9 segments, and 9-MPA and sestamibi uptake were scored from 0 (normal) to 3 (no activity) in each segment. Lower uptake of 9-MPA than of sestamibi was defined as a mismatch. Myocardial segments showing improvement in wall motion during low-dose dobutamine infusion (5-10 microg/kg/ min) were considered viable. RESULTS: The 9-MPA images were of high quality for all patients. Myocardial uptake of 9-MPA was lower in ischemic myocardium than in nonischemic myocardium (58.2%+/-14.2% versus 91.9%+/-6.5%, P<0.0001). Clearance of 9-MPA from ischemic myocardium was slower than that from nonischemic myocardium (10.2%+/-11.7% versus 19.1%+/-5.9%, P<0.01). A mismatch was seen in 10 of 15 patients, and 18 of 20 (90%) mismatched segments were defined as viable by dobutamine echocardiography. Conversely, 18 of 20 (90%) matched segments did not show any improvement in function during dobutamine stimulation (P<0.0001). Uptake of 9-MPA in nonviable segments was lower than that in dysfunctional but viable segments (P<0.05), and 9-MPA clearance from nonviable segments was slower than that from viable segments (P<0.05). CONCLUSION: The imaging characteristics of 9-MPA for SPECT are excellent, allowing noninvasive assessment of myocardial fatty acid uptake. Myocardial imaging with 9-MPA may reveal impaired fatty acid uptake in dysfunctional but viable myocardium and thus provide useful information for clinical decision making in ACS.     

F18-fluorodeoxyglucose single-photon emission computed tomography predicts functional outcome of dyssynergic myocardium after surgical revascularization

Background  Prediction of functional recovery after revascularization is possible with positron emission tomography and F18-fluorodeoxyglucose (FDG). Recently, the use of FDG in combination with single-photon emission computed tomography (SPECT), with 511 keV collimators, has been proposed to allow more widespread use of FDG. In the current study we aimed to predict improvement of regional left ventricular function after surgical revascularization with FDG and SPECT. Methods and Results  Twenty-seven patients with regional wall motion abnormalities (on echocardiography) underwent early thallium-201 (TI-201) SPECT to assess perfusion and FDG SPECT to assess regional glucose uptake. The left ventricular myocardium was divided into 13 segments. For each segment, tracer uptake was evaluated visually (with the use of a 4-point scoring system) by consensus of two observers. Myocardial viability was determined in dyssynergic segments on echocardiography and defined as normal perfusion or increased FDG uptake in a perfusion defect (mismatch). Absence of viability was defined as a perfusion defect without increased FDG uptake (match). Improvement of regional, wall motion was assessed 3 months after revascularization. In the group of segments that were viable on FDG/TI-201 SPECT (n=64), the segmental wall motion score decreased from 1.4±0.5 to 0.6±0.7 (p<0.01), whereas the segmental wall motion score remained unchanged in nonviable segments (n=72): 1.6±0.5 versus 1.5±0.6 (not significant). Forty-six (72%) of the 64 segments that were viable on FDG/TI-201 SPECT demonstrated improved contractile function after coronary revascularization. In contrast, only 7 (10%) of 72 nonviable segments on FDG/TI-201 SPECT showed improvement in function after revascularization (p<0.01 versus viable segments). The sensitivity, specificity, and positive and negative predictive values were 87%, 78%, 72%, and 90%, respectively. Conclusion  This study shows that FDG/TI-201 SPECT can identify patients who improve in regional ventricular function after revascularization.     

Detection of coronary artery disease: Comparison between technetium 99m-labeled sestamibi single-photon emission computed tomography and two-dimensional echocardiography with dipyridamole low-level exercise-stress

Background

Myocardial perfusion imaging in conjunction with dipyridamole low-level exercise stress has proved its value in the evaluation of patients with coronary artery disease (CAD). Simultaneous wall motion analysis by two-dimensional (2D) echocardiography may provide additional information beyond that obtained by myocardial perfusion imaging alone. The purpose of this study was to compare ^99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) and 2D echocardiography for the evaluation of CAD according to a dipyridamole low-level bicycle exercise stress protocol.

Methods and Results

We studied 35 consecutive patients referred for the evaluation of chest pain who had undergone coronary arteriography. ^99mTc-labeled sestamibi SPECT and 2D echocardiography agreed in 27 patients (80%) studied for overall detection of CAD. On a segmental basis, agreement was found between SPECT and 2D echocardiography in 124 (73%) of 170 segments (Cohen’s kappa=0.43). The accuracy of the combined assessment of myocardial perfusion and echocardiographic wall motion in detecting CAD was 86%, which was not different from the accuracy of SPECT alone (80%; difference not significant) but significantly higher than for 2D echocardiography alone (71%; p=0.03). In the detection of individual coronary artery stenoses, SPECT had a significantly higher accuracy for detecting left anterior descending coronary artery lesions than had 2D echocardiography (80% vs 60%; p<0.01); combining the two methods did not improve the accuracy (80%). The combined assessment slightly improved the accuracy for detecting left circumflex coronary artery stenoses from 71% to 83% (p=0.05).

Conclusion

The combined simultaneous assessment of myocardial perfusion by ^99mTc-labeled sestamibi SPECT and wall motion by 2D echocardiography did not significantly improve overall accuracy over that obtained by ^99mTc-labeled sestamibi SPECT alone. Therefore ^99mTc-labeled sestamibi SPECT with dipyridamole low-level exercise stress appears the preferred imaging modality for the evaluation of patients with CAD.     

Usefulness and limitations of ECG-gated myocardial single-photon emission computed tomography with 99mTc-methoxy-isobutyl-isonitrile (MIBI) in patients with prior myocardial infarction]

To evaluate the relationship between regional wall motion and 99mTc-methoxy-isobutyl-isonitrile (MIBI) uptake, ECG-gated single-photon emission computed tomography (SPECT) with 99mTc-MIBI was performed in 20 patients with prior myocardial infarction. The left ventricular images at end-diastole (ED) and end-systole (ES) were divided into 39 segments, respectively. Based on circumferential profile analysis, relative uptake (%EDc, %ESc), percent count increase (% delta C), and normalized percent count increase (% delta Cn) were analyzed in each segment and compared with regional wall motion indices assessed by echocardiography and left ventriculography. ECG-gated SPECT with 99mTc-MIBI provided high contrast tomograms of the left ventricular myocardium. %EDc and %ESc showed good correlations with regional wall motion indices. % delta C and % delta Cn, however, showed lower correlations compared with %EDc and %ESc. In conclusion, high-quality left ventricular images were obtained with 99mTc-MIBI ECG-gated SPECT, but quantitative analysis based on only percent count increase (% delta C) have limitations for evaluation of regional wall motion.     

MR多技术扫描检测活性心肌及其影像学对比的实验研究

目的 评估各种影像学方法检测活性心肌的价值。材料与方法 建立慢性心肌缺血模型猪10头,分别于制作模型前和后1～2月进行磁共振多技术扫描及小剂量多巴酚丁胺负荷超声心动图（LDDSE）、^201TI单光子发射计算机体层显像（^201TI SPECT）、正电子发射体层显像（^18F-PET）检查,判断心肌缺血区和坏死区的大小,并与病理结果对照了解各种方法的敏感性、特异性。结果 7头动物顺利完成所有检查,负荷磁共振电影扫描见10个（8．93％）节段为梗死心肌,6个（5．36％）节段为缺血心肌;心肌灌注扫描见34个（30．35％）节段缺血,心肌活性扫描见12个（10．71％）节段坏死。LDDSE检查见8个（7．14％）节段为梗死心肌,9个（8．04％）节段为缺血心肌。SPECT检查见9个（8．04％）节段为梗死心肌。PET检查见17个（15．18％）节段为梗死心肌。TTC染色见14个（12．50％）节段为梗死区。MR电影检出的坏死节段比TTC染色显示的节段少并有统计学意义（P=0．0455,Kappa=0．8100）;MR活性扫描检出的坏死节段比TTC染色显示的坏死节段略少但无统计学意义（P=0．1573,Kappa=0．9130）。LDDSE检出的坏死节段较TTC染色显示的节段少并有统计学意义（P=0．0140,Kappa=0．7000）;PET检出的坏死节段多于磁共振活性扫描（P=0．0253,Kappa=0．8028）和MR电影扫描（P=0．0082,Kappa=0．7079）并有统计学意义;亦多于TTC染色显示的坏死节段（P=0．0833,Kappa=0．8879）,但无统计学意义;SPECT检出的坏死节段比TTC染色显示的节段少并有统计学意义（P=0．0253,Kappa=0．7590）。以TTC染色结果为金标准,MRI电影、MRI活性扫描、LDDSE、SPECT、PET检出无活性心肌的敏感性、特异性分别为71．43％、100％;85．71％、100％;57．10％、100％;64．29％、100％;100％、96．94％。结论 MR多技术扫描可结合形态、功能及灌注多种方法检测活性心肌．清晰显示心肌梗死的位置、程度,并可对左窒室壁运动进行直观显示,且价格相对PET便宜;磁共振和PET、病理结果均有较高一致性。PET高估心肌坏死范围,且不能判断心肌梗死的透壁程度。SPECT和LDDSE低估心肌活性。而且亦不能显示心肌梗死的透壁程度。