^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。     

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。     

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。     

18F-FDG PET显像和超声心动图检测心肌梗死面心肌存活

目的　比较1 8F 脱氧葡萄糖 (FDG)PET显像和超声心动图 (UCG)对心肌梗死面存活心肌检查的符合情况。方法　 4 0例心肌梗死患者 ,男 38例 ,女 2例 ,平均年龄 (5 6± 11)岁 ,分别行1 8F FDGPET显像及UCG检查。结果　PET显像检出坏死心肌 2 6 9个节段 ,UCG发现室壁节段运动异常2 15个节段 (检出率 79 9% )。PET显像检测心肌梗死面有无心肌存活与UCG观察室壁运动情况显著相关 (χ2 =4 9 5 3,P <0 0 0 1)。UCG室壁运动轻微异常的节段与PET显像示有部分心肌存活相关 ;而UCG室壁运动消失及矛盾运动的节段 ,与PET显像示心肌无存活相关 (χ2 =4 7 9,P <0 0 0 1)。同时PET显像在UCG室壁矛盾运动节段检出部分节段有心肌存活 (u =3 6 8,P <0 0 1)。结论　常规UCG检查观察心脏室壁运动可以初步筛选梗死累及部位的心肌存活情况 ;对UCG发现大面积室壁运动消失甚至室壁矛盾运动的患者 ,应行心肌PET显像。     

13N-NH3 PET显像诊断星形细胞瘤

目的　探讨13 N NH3 PET显像诊断星形细胞瘤的可行性。方法　 7例星形细胞瘤患者 ,包括术前星形细胞瘤 3例 ,术后复发 2例 ,术后放疗后脑损伤或坏死 2例。 7例中 6例在 2d内完成13 N NH3 和18F 脱氧葡萄糖 (FDG)PET显像 ,1例仅行13 N NH3 显像。采用对称感兴趣区 (ROI)方法分析肿瘤与正常脑白质 (T WM)的13 N NH3 、18F FDG的摄取比值。结果　 3例术前星形细胞瘤和 2例术后复发肿瘤病灶均明显摄取13 N NH3 ,T WM平均为 1 82± 0 2 1,其中 1例术后病理检查为星形细胞瘤Ⅰ级患者 ,18F FDGPET显像示局部病变区放射性分布明显减低 ,T WM为 0 97,相应位置13 N NH3 显像呈高代谢 ,T WM为 1 98。 2例术后放疗后脑损伤或坏死患者13 N NH3 及18F FDGPET显像均示局部病变区为放射性分布缺损或明显减低。结论　星形细胞瘤摄取13 N NH3 ;13 N NH3 PET显像对星形细胞瘤术前诊断、术后放疗后肿瘤复发及放射性脑坏死或损伤的鉴别诊断有一定价值     

201Tl SPECT心肌显像在激光心肌再血管化治疗中的应用

目的　评价2 0 1 TlSPECT心肌显像在激光心肌再血管化 (TMLR)治疗缺血性心脏病中的价值。方法　 19例心肌梗死病人均行TMLR治疗 ,经左第 5肋间 ,前外侧切口 ,显露心脏 ,使用高能量 (80 0W)CO2 心脏激光治疗仪于心脏跳动中作心肌打孔 ,经食管超声监测打孔情况 ,打孔部位在左心室游离壁 ,平均打孔前壁 (8 3± 2 9)个 ,侧壁 (6 9± 2 5 )个 ,下壁 (5 4± 2 0 )个 ,心尖 (5 3± 4 4)个。在TMLR治疗前 ,均行潘生丁负荷试验 (ST) “再分布”(RD) 硝酸甘油 (NTG)介入 再注射 (NTG RI) 2 0 1 TlSPECT心肌显像。潘生丁剂量按体重 0 7mg kg ,4min内慢速静脉推注 ,注射完 2min后 ,静脉注射2 0 1 Tl 111MBq ,10min后行SPECT心肌显像 ,“再分布”显像于 3～ 4h后进行。继而舌下含服硝酸甘油 0 6mg ,静脉再注射2 0 1 Tl37MBq,10min后行第 3次SPECT显像。TMLR治疗后随访 3个月显像17例 ,6个月显像 11例 ,1a显像 5例。结果　 19例病人共有 5 6个心肌灌注异常节段 ,随机选取 45个节段行TMLR治疗。其中术后 18个节段心肌血流灌注有改善 ,治疗有效率为 40 %。术前RD NTG RI2 0 1 TlSPECT心肌显像有显著再分布的 18个节段 ,术后 77 8% (14个 )节段心肌灌注改善。术前2 0 1 TlSPECTRD心肌显像图上有显著再分布的     

~(201)Tl再注射心肌显像和再注射后延迟显像检测心肌存活的对比研究

为了解２０１Ｔｌ再注射及再注射后延迟显像对心肌存活的检测能力，对６２例心肌梗塞患者进行了２０１Ｔｌ运动、３～５小时再分布、２０１Ｔｌ再注射后１６～３５分钟及再注射后１２～１９小时延迟心肌断层显像。１５例患者于显像后行经皮冠状动脉腔内成形术（ＰＴＣＡ），并于ＰＴＣＡ后重复运动再分布心肌显像。结果：６２例患者运动再分布显像共有１２６个不可逆缺损节段，其中４８个节段再注射后１６～３５分钟出现放射性填充，心肌存活检出率为３８１％（４８／１２６）；５１个节段再注射后延迟显像出现再分布，心肌存活检出率为４０５％（５１／１２６）。两种显像方案的检出率差异无显著性（χ２＝０１６，Ｐ＞００５），但两者结合６２个节段示有放射性填充，心肌存活检出率可提高到４９２％（６２／１２６）。１５例患者ＰＴＣＡ前共检出１７个心肌存活节段，术后１２个节段２０１Ｔｌ灌注改善，阳性预测率为７０６％；ＰＴＣＡ前检出１１个梗塞节段，术后９个节段２０１Ｔｌ摄取无改善，阴性预测率为８１８％。结果表明：２０１Ｔｌ再注射与延迟显像心肌存活检出率无明显差别，但两者联合应用可提高检出率。     

心脏X综合征双嘧达莫负荷心肌201Tl SPECT显像分析

目的 观察心脏X综合征患者的双嘧达莫负荷心肌201TI SPECT显像特点,分析其表现机制.方法 选取临床符合心脏X综合征诊断标准的患者29例,按体质量0.56 mg/kg予双嘧达莫,于4 min内静脉注射,10及240 min后分别进行双嘧达莫负荷心肌201T1 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.结果 所有29例患者的双嘧达莫负荷201T1图像(10 min)均显示左室心肌放射性分布正常.延迟(240 min)显像时有25例(86.2%)患者(共200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34个节段:前壁6个(17.6%)、下壁10个(29.4%)、前间壁4个(11.8%)、心尖部11个(32.4%)、前侧壁3个(8.8%).后间壁、后侧壁和后壁无放射性分布异常;其余4例(13.8%)患者延迟显像则为放射性分布正常.结论 双嘧达莫负荷心肌201T1 SPECT显像的"反向再分布"现象对于心脏X综合征的诊断具有一定的临床意义.     

大剂量硝酸甘油介入~(99m)Tc-MIBI心肌SPECT判定存活心肌的研究

目的：探讨大剂量硝酸甘油介入（大剂量硝充法）99mTc-MIBI心肌SPECT对存活心肌判定的价值。材料和方法：对44例大剂量硝充组和31例小剂量硝充组的心肌梗塞患者均行静息和硝充法心肌显像。采用9节段评分法对两次显像进行了比较。其中两组中分别有18例和17例于冠脉血管再通术（PTCA或CABG）后半年内再次复查了静息心肌显像并与术前比较。结果：大剂量硝充组静息心肌显像灌注异常节段为154个，硝充后有77个节段呈现了再分布，总再分布率为50．0％（77／154）；小剂量硝充组静息心肌显像灌注异常节段为110个，硝充后有35个节段呈现了再分布，总再分布率为31．8％（35／110）。大剂量和小剂量组中18例和17例PTCA和CABG患者术后静息心肌显像与硝充法心肌显像比较阳性符合率分别为85．7％和68．8％．预测准确率为对71．9％和50．9％。结论：大剂量硝酸甘油介入99Tc-MIBI心肌SPECT具有较高的存活心肌检出率和预测准确性。     

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。     

Evaluation of myocardial viability following acute myocardial infarctic using201Tl SPECT after thallium-glucose-insulin infusion —Comparison with18F-FDG positron emission tomography—

OBJECTIVE AND METHODS: The aim of this study was to evaluate myocardial viability in patients after acute myocardial infarction (AMI). We compared 201Tl SPECT after 201Tl with GIK (10% glucose 250 ml, insulin 5 U and KCl 10 mEq) infusion (GIK-201Tl) with resting 201Tl and 99mTc-pyrophosphate (PYP) dual SPECT, positron emission computed tomography (PET) using 18F-fluorodeoxyglucose (18F-FDG) in 21 patients with their first AMI, who all underwent successful reperfusion. GIK-201Tl SPECT, 201Tl and 99mTc-PYP dual SPECT were done within 10 days after admission and 18F-FDG-PET was performed at 3 weeks. GIK-201Tl SPECT was obtained after 30 min of GIK-201Tl infusion. 18F-FDG (370 MBq) was injected intravenously after oral glucose (1 g/ kg) loading, and then PET was obtained. PET and SPECT images were divided into 20 segments. Regional tracer uptake was scored using a 4-point scoring system (3 = normal to 0 = defect), and summed to a regional uptake score (RUS). Regional area means the infarcted area in which 99mTc-PYP accumulated. The number of decreased uptake segments (ES) was then determined. The infarcted area was defined as the area of 99mTc-PYP uptake. RESULTS: The ESs for the GIK-201Tl and 18F-FDG-PET images were significantly lower than the number of 99mTc-PYP uptake segments. The RUS for GIK-201Tl was higher than that for resting-201Tl imaging and similar to those for 18F-FDG-PET. CONCLUSIONS: In the detection of myocardial viability following AMI, GIK-201Tl imaging is useful with findings similar to those of 18F-FDG-PET.     

Metabolic activity in the areas of new fill-in after thallium-201 reinjection: comparison with positron emission tomography using fluorine-18-deoxyglucose

Reinjection of thallium-201 after recording the 3-hr delayed scan often demonstrates improvement in areas of persistent abnormalities. To determine the metabolic activity of these areas, the changes seen on stress/redistribution/reinjection thallium SPECT were compared with PET using fluorine-18-fluorodeoxyglucose (FDG) in 18 patients with coronary artery disease. Of 48 segments showing no redistribution on the delayed scan, the reinjection scan identified new fill-in in 20 segments (42%), all of which demonstrated FDG uptake. In contrast, only 7 of the 28 segments (25%) showing no fill-in after reinjection were PET viable (p less than 0.01). Eleven patients had coronary bypass graft surgery after the radionuclide study. The majority of the segments showing redistribution (87%) and new fill-in after reinjection (65%) improved in wall motion, whereas only eight segments (25%) without new fill-in improved after surgery. Of those without new fill-in, two segments showing PET ischemia improved in wall motion, whereas the remaining six segments showing PET scar did not improve after surgery. Thus, the segments showing new fill-in after reinjection are PET viable myocardium. However, reinjection thallium imaging still underestimates the extent of tissue viability compared to PET imaging.     

Determination of Myocardial Viability with ECG-Gated Fluorodeoxyglucose F-18 Positron Emission Tomography

OBJECTIVE: We hypothesize that ECG-gated positron emission tomography (PET) using Fluorodeoxyglucose F-18 (FDG) alone can determine myocardial viability by identifying dysfunctional myocardium with preserved glucose metabolism. We compared the contraction-metabolism pattern of gated FDG PET with the perfusion-metabolism pattern of conventional PET using N-13 ammonia (NH(3)) as a perfusion agent and FDG as a glucose metabolism agent in 21 consecutive patients with chronic coronary artery disease with left ventricular dysfunction (mean ejection fraction 23.6 +/- 7.7%).METHODS: The left ventricle was divided into 17 segments. Uptakes of NH(3) and FDG were scored from absent (0) to normal (4), and wall motion was scored from dyskinesia (-1) to normal (3). Scores were determined by the visual interpretation of the majority of 3 blinded expert readers. Viable myocardium was defined by normal or mildly reduced uptakes of both NH(3) and FDG, perfusion-metabolism mismatch on NH(3)-FDG PET, or normal to mildly reduced uptake of FDG with regional dysfunction on gated FDG PET.RESULTS: Gated FDG PET identified 184 segments as viable, all of which were determined as viable by NH(3)-FDG PET. Among 125 segments identified as nonviable by NH(3)-FDG PET, 76 segments were determined as nonviable by NH(3)-FDG PET. The results provided a positive and negative predictive value of gated FDG PET for the determination of myocardial viability to be 100% and 60.8%, respectively.CONCLUSIONS: Gated FDG PET has a high positive predictive value (100%) for the identification of viable myocardium.     

The comparison of 2-18F-2-deoxyglucose and 15-(ortho-123I-phenyl)-pentadecanoic acid uptake in persisting defects on thallium-201 tomography in myocardial infarction

The myocardial uptake of glucose and fatty acids into 201Tl redistribution defects were studied in 32 patients with myocardial infarction by tomography using 2-18F-2-deoxyglucose (FDG) and 15-(ortho-123I-phenyl)-pentadecanoic acid (oPPA). A total of 1153 segments were analyzed, 408 (35%) of which showed a persistent thallium-defect in stress-redistribution images. Of the segments with a decreased 201Tl uptake in these redistribution tomograms, 50.5% had a decreased uptake of both FDG and oPPA; in 21.8% FDG as well as oPPA uptake was within normal range. Normal FDG uptake but decreased oPPA uptake was detected in 17.4%, whereas 10.3% of the segments had normal oPPA uptake but decreased FDG uptake (chi-square test, p less than 0.001). A significant correlation of FDG and oPPA uptake (r = 0.51) was found in the segments with persistent 201Tl defect. Thus, a substantial fraction of persistent thallium-defects after healed myocardial infarction exhibit FDG as well as oPPA uptake, probably due to residual fatty acid metabolism in partially ischemic regions.     

Comparison between rest technetium-99m-tetrofosmin and rest-redistribution thallium-201 SPECT in stable patients with healed myocardial infarction.

Resting (99m)Tc-tetrofosmin (TF) uptake was compared with thallium ((201)Tl) rest-redistribution (R-RD) uptake in patients with previous myocardial infarction (MI) and significant coronary artery disease (CAD) to assess the ability of TF to detect viable myocardium. We studied 30 patients (21 males and nine females, mean age 53.9+/-12.5 years) with prior MI and left ventricular dysfunction who had been referred for coronary revascularization procedures. Myocardial single photon emission computed tomography (SPECT) images were obtained 1 h after injection of 750 MBq of TF. Within 1 week of the TF study, R-RD (201)Tl SPECT imaging was performed after injection of 111 MBq of (201)Tl . Quantitative analysis was performed in 21 segments. Viability was defined as the presence of tracer uptake greater than 50% of the peak activity on baseline studies or after reversibility. There was significant correlation between the quantitative regional R-RD (201)Tl activity and the resting TF activity (r=0.88, P<0.001). Quantitative analysis showed that the uptake of the two tracers was comparable in normal segments as well as in segments with fixed (201)Tl defects. In contrast, in segments with reversible (201)Tl defects, TF uptake was significantly greater than resting (201)Tl uptake, but lower than R-RD (201)Tl uptake. There were 52 segments (47% of the severely reduced segments on TF images) that showed no viability with TF, but were viable on the redistribution (201)Tl studies. We conclude that quantitative resting TF SPECT underestimates the presence of viable myocardium compared with R-RD (201)Tl imaging on the basis of using 50% of the peak activity as the viability threshold.     

Clinical value of thallium-201 reinjection after delayed imaging in patient showing incomplete or no redistribution

To asses clinical value of Tl-201 (Tl) reinjection after delayed imaging, 30 patients who showed incomplete or no redistribution in stress-delayed Tl myocardial scintigraphy were studied. Of 76 myocardial segments with incomplete or no redistribution on the delayed images, 29 segments (38%) showed improvement of Tl uptake after Tl reinjection. Reinjection was considered effective in 24 segments (32%) where no or little redistribution were observed on the delayed images but improved after reinjection. The contrast ventriculography showed less wall motion abnormality in the segments with improvement after reinjection than that without improvement after reinjection (regional wall motion score: 2.55 +/- 0.50 vs. 0.59 +/- 0.97 p less than 0.01). History of myocardial infarction was also significantly less in the former (p less than 0.05). We conclude that Tl reinjection is useful in cases showing no or equivocal redistribution on the delayed images.     

Assessment of myocardial viability by quantitative analysis of stress Tl-SPECT--comparison with FDG-PET

Stress Tl-201 tomography (SPECT) is widely used for evaluating myocardial viability. To assess its value, redistribution (RD) on SPECT was compared with metabolic imaging using FDG. Thirty patients with coronary artery disease underwent stress-3 hour Tl-201 SPECT and PET using N-13 ammonia and FDG. RD was classified into 4 grading, including complete RD (CR), incomplete RD (IR), persistent defect (PD) and additional minimal RD (MR) defined as no definite RD on visual analysis but faint RD with Bull's eye quantitative analysis (QNT). All but one segment with CR or IR were viable regions (normal or ischemic regions) by PET. Of 74 segments without RD on visual analysis, 31 segments (42%) had RD by QNT (MR). All of them were viable regions by PET. Thus, QNT identified 31 segments (63%) of the metabolically viable segments which the visual Tl-201 analysis did not show RD and classified as myocardial scar. However, even such QNT cannot detect ischemic myocardium in 18 segments (42%) containing metabolic activity on PET. These data indicate that QNT of RD on Tl-201 SPECT is considered as a valuable means for assessing myocardial ischemia.     

Value and limitation of myocardial fluorodeoxyglucose single photon emission computed tomography using ultra-high energy collimators for assessing myocardial viability

Single photon emission computed tomography (SPECT) using ultra-high energy collimators permits wide clinical application of (18)F-fluorodeoxyglucose (FDG) imaging without the use of expensive positron emission tomography (PET) cameras. This study was designed to evaluate the value of FDG SPECT using ultra-high energy collimators in assessing myocardial viability compared with FDG PET on a regional basis. We prospectively studied 33 patients with ischaemic heart disease. The patients were injected with 555 MBq of FDG under a hyperinsulinaemic glucose clamp, and FDG PET was performed 40 min later. FDG SPECT using ultra-high energy collimators was performed immediately after FDG PET. The images of the left ventricular myocardium were divided into nine segments and the regional defect score was assessed visually using a four-point scale (0=normal to 3=defect). Regional FDG uptake (%uptake) was quantitatively analysed using polar maps. In 297 segments of all the 33 patients, agreement between the defect scores based on FDG SPECT images and those based on FDG PET images was 70%, and agreement within one rank was 96% (kappa value=0.52). The %uptake based on FDG SPECT images significantly correlated with that based on FDG PET images (r=0.77, P<0.01). However, the defect scores in the inferior wall based on FDG SPECT images were higher (1.41+/-1.14) than those based on FDG PET images (1.06+/-1.12, P<0.01). When the viable region is defined as %uptake > or =50% in FDG PET studies, the optimal cut-off level of %uptake based on FDG SPECT images was 60% in the anterior wall, apex, septum and lateral wall (accuracies, 97%, 93%, 96% and 99%, respectively), and 45% in the inferior wall (accuracy, 99%). It is concluded that FDG SPECT using ultra-high energy collimators can be used for the assessment of myocardial viability as accurately as FDG PET. However, a slight difference was observed in the defect scores mainly due to attenuation in the inferior wall. Therefore, a slightly different cut-off level for assessing myocardial viability should be applied to the inferior wall when using FDG SPECT.     

F-18 fluoro deoxyglucose SPECT for assessment of myocardial viability

Identification of myocardial viability in hypokinetic segments is important in patients with ischemic cardiomyopathy because systolic dysfunction improves with revascularization. Positron emission tomography (PET) F-18 fluoro deoxyglucose (FDG) uptake has been demonstrated as an accurate indicator of metabolically active and thus viable myocardium. F-18 FDG single photon emission computed tomography (SPECT) has recently been introduced and offers a technically easier and less costly alternative to PET imaging for determination of myocardial viability. A body of literature demonstrates that F-18 FDG SPECT can reliably be performed with SPECT hardware equipped with 511-keV collimators, which provides an accurate assessment of myocardial viability. F-18 FDG SPECT offers data similar to those offered by F-18 FDG PET and compares favorably with other imaging modalities, including rest-redistribution and stress-reinjection thallium-201 myocardial perfusion imaging, gated technetium 99m SPECT, and low-dose dobutamine echocardiography.