Load independence of radionuclide diastolic filling measurements in acute coronary occlusion

Background  

An accurate noninvasive method for measuring the effects of pharmacologic agents on active relaxation of the left ventricle would provide a valuable tool for monitoring the treatment of diastolic heart failure related to coronary artery disease.     

放射性核素显像在心力衰竭中的应用

放射性核素显像在测定心室功能,评价心力衰竭的严重程度,了解心肌血流灌注、心肌活力及心脏交感神经功能,鉴别心力衰竭的病因,判断预后,指导临床治疗和评估疗效等多方面都有重要的临床价值。     

Multigated radionuclide study of the total artificial heart

A permanent total artificial heart, the Jarvik-7, was implanted into a 61-year-old male with a severe cardiomyopathy. Gated radionuclide studies were performed in the patient both prior to surgery and following implantation. Preoperative gated radionuclide cardiac studies revealed marked left ventricular enlargement, severe hypokinesis and a left ventricular ejection fraction of 10%. The right ventricle was moderately enlarged with a 27% ejection fraction. Following implantation of the Jarvik-7 artificial heart, gated cardiac studies were performed with a computer gated by a signal from the heart controller. The left ventricular ejection fraction was 69% and the right ventricular ejection fraction was 62%. This compared to a theoretical ejection fraction of 74% for each ventricle based on chamber anatomy. There was excellent ventricular emptying. Phase analysis showed uniform diaphragm motion. The use of gated cardiac studies in humans may prove helpful in evaluating mechanical problems with the artificial heart, such as malfunction of the diaphragm, before they become clinically apparent.     

Diagnostic accuracy of antimyosin scintigraphy in suspected myocarditis

Background  

Radiolabeled antibody specific for cardiac myosin administered intravenously has been used to define noninvasively regions of myocardial necrosis. Inflammatory heart disorders such as myocarditis and heart transplant rejection demonstrate diffuse and often faint myocardial uptake of antimyosin antibody. This study was undertaken to evaluate the reproducibility and diagnostic accuracy of antimyosin antibody imaging for the detection of patients with suspected myocarditis.     

Diagnostic utility of tomographic myocardial perfusion imaging with technetium 99m furifosmin (Q12) compared with thallium 201: Results of a phase III multicenter trial

Background  

Based on physical properties, ^99mTc-labeled perfusion agents offer several advantages over ²⁰¹Tl for myocardial perfusion imaging. The results of in vivo and experimental studies, along with preliminary experience in human subjects, have shown ^99mTc-labeled furifosmin to be a promising new perfusion tracer. The purpose of this study was to evaluate the safety of a new myocardial perfusion agent, ^99mTc-labeled furifosmin (Q12), and determine the concordance of furifosmin perfusion scintigraphy to ²⁰¹Tl imaging. In addition, we sought to determine the normalcy rate of myocardial scintigraphy with furifosmin.     

Myocardial perfusion imaging in pediatric cardiology

Myocardial perfusion imaging (MPI) is an important procedure in pediatric cardiology in terms of evaluating myocardial ischemia, infarction and damage associated with various congenital or acquired heart diseases, such as Kawasaki disease, anomalous origin of the left coronary artery from the pulmonary artery and complete transposition of the great arteries after arterial switch surgery. This type of imaging can detect myocardial damage in the morphological right ventricle when it functions as a systemic pumping chamber in patients with complex congenital heart diseases after intra-cardiac repair. Myocardial perfusion imaging can also evaluate myocardial damage associated with primary or secondary cardiomyopathy in children. The magnitude of increased right ventricular uptake on MPI is a useful noninvasive means of estimating right ventricular pressure overload due to congenital heart or pulmonary diseases. This article reviews myocardial perfusion tracers and pharmacological stress tests used to diagnose heart conditions in children, and the current clinical roles of MPI in pediatric cardiology.     

弥漫性分布不均匀相位图对病毒性心肌炎的诊断价值

为了探讨弥漫性分布不均匀相位图对病毒性心肌炎的诊断价值，对病毒性心肌炎３２例、缺血性心脏病４１例、扩张型心肌病２１例和正常人３２例进行了门控心血池显像检查。结查发现：病毒性心肌炎的弥漫性分布不均匀相位图阳性率为８４．４％，明显高于缺血性心脏病组１２．２％、扩张型心肌病组４７．６％和正常对照组９．４％（Ｐ＜０．０１），也明显高于ＬＶＥＦ（３４．４％，Ｐ＜０．０１）。提示弥漫性分布不均匀相位图是诊断病毒性心肌炎有价值的指标。     

^99mTc-MIBI门控心肌SPECT进行心功能研究的方法学探讨

应用~(99m)Tc-MIBI对30例心脏患者进行首次通过(First Pass)及门控心肌断层(SPECT)显像,利用门控心肌断层显像在观察心肌血流灌注变化的同时可得到心动周期内不同时刻的心室腔变化图像,使患者接受一次注射采集可同时获得心肌灌注评价与心功能评价成为可能,提高了心肌断层的临床应用价值。文章中将门控心肌断层显像所得左室心腔面积收缩分数(CFLVA)与首次通过法所得EF值应用统计学方法进行了相关与回归分析,从而验证了此方法的可行性。     

Clinical characteristics and referral pattern of patients with left ventricular dysfunction and significant coronary artery disease undergoing radionuclide imaging

BACKGROUND: Many observational studies that predict patient outcomes have examined the use of myocardial perfusion imaging results. However, a referral pattern for radionuclide testing could bias these analyses and should be determined. These patients may also differ with regard to the extent of coronary artery disease (CAD). All of these differences must be incorporated into proper outcomes examinations. We sought to identify the nuclear perfusion imaging referral pattern for patients with left ventricular (LV) dysfunction and significant CAD. METHODS AND RESULTS: Patients with LV dysfunction and CAD (n = 2951) meeting our inclusion criteria were compared by receipt or absence of radionuclide perfusion testing within 6 months before or after angiography. Pearson chi2 and Kruskal-Wallis analyses were used to examine differences in baseline characteristics and catheterization results, whereas logistic regression modeling was applied to predict nuclear imaging referral before and after catheterization. Precatheterization nuclear cohort patients were more likely to be minority patients (odds ratio [OR], 1.34; P =.0083) with previous cardiac revascularization (OR, 2.27; P =.0001), Charlson comorbidity index greater than 1 (OR, 1.146; P =.0091), and heart failure symptoms (OR, 1.62; P =.0001) than those without imaging. They were less likely to have a myocardial infarction (OR, 0.464; P =.0001). After catheterization, the nuclear patients were more likely to have had congestive heart failure (OR, 1.452; P =.0019), a myocardial infarction (OR, 1.353; P =.0371), an ejection fraction lower than 30% (OR, 1.058; P =.0002), and prior revascularization (OR, 1.880; P =.0001). In addition, they had fewer diseased vessels (OR, 0.731; P =.0001). CONCLUSIONS: Bias exists in nuclear referral for patients with LV dysfunction and significant CAD and must be considered when interpreting observational studies on this topic.     

Detection of deep venous thrombosis by DMP 444, a platelet IIb/IIIa antagonist: A preliminary report

BACKGROUND: We report a method for detection of deep venous thrombosis with a technetium 99m-labeled peptide (DMP 444). The N-methyl-arginine-glycine-aspartic acid sequence on DMP 444 binds the glycoprotein IIb/IIIa receptor on activated platelets (inhibition constant [IC50] for fibrinogen binding = 6 nmol/L). METHODS: DMP 444 (23 to 27 mCi) was injected into 11 patients with clinical suspicion of deep venous thrombosis, diagnostic confirmation by ultrasound, and a positive D-dimer test result. Planar images in the anterior and posterior projections were obtained at 10 to 40 minutes, 50 to 80 minutes, and 120 to 150 minutes after injection. RESULTS: No clinically significant adverse effects were noted after DMP 444 administration. One patient (excluded from the analysis) withdrew consent, so image acquisition was not complete. By 10 to 40 minutes after injection, 8 of 10 patients demonstrated an area of increased activity that was clearly related to the abnormality noted on ultrasound. Most patients were taking warfarin (Coumadin) and heparin (n = 8) or heparin (n = 1) and warfarin (n = 1) alone at the time of the imaging. The average time from onset of symptoms to injection of DMP 444 was 5 days (range 1 to 18 days). CONCLUSION: These preliminary human studies indicate that DMP 444 is safe and may be of value in the diagnosis of deep venous thrombosis.     

The relationship between clinical stage,prognosis and myocardial damage in patients with Duchenne-type muscular dystrophy: five-year follow-up study

The evaluation of myocardial damage by [123I] 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) imaging, which represents free fatty acid metabolism, has not been reported in patients with Duchenne-type muscular dystrophy (DMD). To date, the relationship between clinical stage, prognosis and myocardial damage has not been evaluated by radionuclear cardiac imaging. The main goal of this study was to elucidate the relationship of quantitative indices of myocardial damage obtained by radionuclear cardiac imaging ([201Tl] and [123I] BMIPP) to clinical stage and incidence of severe cardiac events in patients with Duchenne-type muscular dystrophy (DMD). METHODS: The study population consisted of 28 male patients with DMD. The average age at the beginning of observation was 19.1 +/- 7.4 yrs. Nuclear tomographic imaging was performed using [201Tl] and [123I] BMIPP. The mid-ventricular short axial slices were classified into four anatomical regions, and the normalized count data in these areas (TL, BM) were obtained. The endpoint was the occurrence of heart failure during the follow up period. RESULTS: Thirteen cases of heart failure occurred during the 5-year follow-up period, including three cases with cardiac death due to congestive heart failure. Clinical staging correlated directly with TL (p = 0.0118) and BM (p = 0.0401) in the whole left ventricle. In regional TL analysis, an association was observed only in the septum (p = 0.0151), and in the anterior (p = 0.0361) region. The only discrepancy between the tracer parameters (TL - BM) in the septum was observed with the radionuclear cardiac values, which exhibited a relationship with cardiac events (p = 0.0124). This discordance, TL < BM, was contrary to that usually observed in patients with ischemic heart disease. CONCLUSION: The septum is the critical area of significance for cardiac events and outcome in patients with DMD. The uptake of [201Tl] in this area was representative of the clinical stage, and TL-BM correlated well with the prognosis.     

Delayed 99mTc-labeled erythrocyte scintigraphy in patients with lower gastrointestinal tract hemorrhage: effect of positive findings on clinical management

RATIONALE AND OBJECTIVES: This study was performed to determine whether the results of delayed technetium 99m (99mTc)-labeled erythrocyte scintigraphy for lower gastrointestinal tract hemorrhage resulted in different clinical management and outcome from that in cases in which the results of initial scintigraphy were negative or equivocal. MATERIALS AND METHODS: The authors retrospectively reviewed all 398 99mTc-labeled erythrocyte scintigraphic studies obtained emergently for lower gastrointestinal tract hemorrhage at their institution between January 1, 1994, and December 7, 2001. Of 67 patients who underwent delayed studies, 37 had positive findings (average delay, 18.4 hours; range, 6-25 hours) and 30 had negative findings (average delay, 20.1 hours; range, 8-26 hours). Clinical management and outcome were compared between these two groups with respect to duration of hospitalization, volume of blood transfusion, mortality, and the percentage who were treated conservatively or referred for angiography, endoscopy, and/or surgery. RESULTS: Patients with positive delayed studies were referred more frequently for angiography than those with negative studies (35% vs 0%, P < .01). There were no significant differences between patients with positive findings and patients with negative findings with respect to mortality (8% vs 0%, P < .32), transfusion requirements (5.6 vs 3.2 units, P < .20), hospitalization (9.5 vs 6.1 days, P < .11), the percentage treated conservatively (35% vs 37%, P < .90), or the percentages referred for endoscopy (49% vs 60%, P < .50) or for surgery (24% vs 17%, P < .64). CONCLUSION: Positive findings at delayed scintigraphy resulted in increased referrals for angiography but had no other effect on clinical course or outcome of lower gastrointestinal tract hemorrhage.     

Nitroimidazoles for imaging hypoxic myocardium

A series of radiopharmaceuticals that incorporate nitroimidazole moieties have been synthesized to detect decreased local tissue pO2. In contrast to agents that localize in proportion to perfusion, these agents concentrate in hypoxic tissue. Myocardium with an intracellular pO2<3 mm Hg (about 25% of normal), which has lost its contractile ability but has maintained its ability to catabolize glucose, can be localized with this imaging technique. When a nitroimidazole enters a viable cell, the molecule undergoes a series of reactions: Initially, the molecule gains a single electron by an enzymatic process in the cytoplasm to form a potentially reactive species, then in the presence of adequate intracellular oxygen levels the molecule is reoxidized. These reactions are repeated until the intact molecule diffuses back out of the cell. In myocytes with reduced oxygen concentration, the reoxidation does not take place, the reactive species appears to undergo additional reduction reactions and remains in the cell. The association of the reduced nitroimidazole and other cellular elements is not irreversible, since these agents clear from hypoxic tissue with a half-life of 4 to 8 hours. In one of the first nitroimidazoles used for in vivo imaging, fluoromisonidazole was the radiopharmaceutical. Two major problems with fluoromisonidazole are its relatively low concentration within the lesion and the need to wait several hours to permit clearance of the agent from the normoxic background tissue (contrast between lesion and background typically<2∶1 at about 90 minutes after injection). Even with high resolution positron emission tomography imaging, this combination of circumstances makes successful evaluation of hypoxic lesions a challenge. The development of single photon agents with longer physical half-lives and comparable biologic properties offer a greater opportunity for successful imaging. In 1992 technetium 99m-labeled nitroimidazoles were described that had in vivo kinetics that were potentially suitable for detection of hypoxic myocardium. Laboratory studies showed preferential binding of these agents to hypoxic myocytes and isolated hearts in vitro and to ischemic myocardial tissue in laboratory animals. Patient studies are planned to determine whether the promise of these agents in laboratory studies can be realized in clinical practice.     

心脏磁共振在体示踪移植细胞的可行性研究

目的：寻找一种能够对移植细胞进行在体示踪的标记方法,为移植细胞存留、迁移提供重要观察手段。方法：从中华小型猪髂骨处抽取骨髓,体外培养扩增骨髓间充质干细胞（MSCs）。将SPIO和MSCs共同孵育培养36h。普鲁士蓝染色评价细胞的标记效率;通过MTT比色实验评价SPIO对细胞生长能力的影响;台盼蓝染色检验标记后细胞的活性;使用Costar Transwell方法评价铁离子对细胞迁移能力的影响;用细胞分化诱导液培养标记后的细胞评价其向成脂肪细胞和成骨细胞的分化能力。在体内实验中将SPIO标记或未标记的自体MSCs注射到心肌内,通过心脏磁共振检查对移植细胞进行在体示踪观察,取材动物心脏行病理检查观察移植细胞的存活、存留。结果：MSCs经铁离子标记后普鲁士蓝染色阳性率在98%以上,可见蓝色颗粒位于细胞浆内,标记细胞电镜切片可见高密度铁颗粒位于细胞浆内。随着培养液中SPIO浓度的增加细胞增殖能力没有明显改变;标记后98%的细胞保持活性;SPIO标记后的细胞保持原有的形态,可继续培养、传代;SDF-1和VEGF诱导的迁移实验发现标记细胞迁移能力没有降低;铁离子标记后细胞仍可向成脂肪细胞和成骨细胞分化。注射到心肌内的SPIO标记的MSCs可通过心脏磁共振检查进行在体示踪,动态观察显示SPIO标记细胞在磁共振图像上表现为低信号,并且在移植后4周仍可成像。病理学检查可以看到移植细胞呈普鲁士蓝染色阳性,并和影像学有很好的一致性。结论：临床使用的SPIO磁共振对比剂可以安全、有效地标记MSCs,心脏磁共振检查可以实现SPIO标记的移植细胞的在体示踪。     

Optimizing the method to calculate right ventricular ejection fraction from first-pass data acquired with a multicrystal camera

Background  

The advantage of radionuclide angiographic techniques used to measure right ventricular ejection fraction (RVEF) is geometry independence, but the weakness is right atrial (RA) overlap. To minimize the effect of RA counts on right ventricular time activity curve (TAC), two regions of interest (ROI), one drawn for the end-diastolic image and one for the end-systolic image, are used for the calculation of RVEF from equilibrium gated blood pool scans (GBPS) and from gated first-pass studies with an Anger camera. A multicrystal camera offers both temporal separation of the bolus to the right side of the heart and good count statistics; therefore first-pass studies performed on a multicrystal camera theoretically should yield the most accurate measurements of RVEF, but few studies have been performed to validate RVEF against a reliable gold standard.     

Optimal timing for initial and redistribution technetium 99m-N-NOET image acquisition

BACKGROUND: Bis (N-ethoxy, N-ethyl dithiocarbamato) nitrido technetium-99m (V) (Tc-99m-N-NOET) is a new Tc-99m-labeled myocardial perfusion imaging agent that redistributes. We sought to determine the optimal timing for acquiring initial and delayed images to maximize sensitivity for the detection of coronary stenoses. METHODS: Twelve anesthetized dogs with critical stenoses of the left anterior descending coronary artery were infused with adenosine (250 microg/kg/min) or MRE-0470, an adenosine A2a agonist (0.6 microg/kg/min x 10 minutes), and Tc-99m-N-NOET (8 mCi; 296 MBq) was injected intravenously at peak flow. Myocardial and lung Tc-99m-N-NOET activities were determined by serial quantitative imaging and arterial blood sampling was performed over 2 hours. RESULTS: Left anterior descending/left circumflex artery defect count ratios showed rapid redistribution during the first 10 minutes after Tc-99m-N-NOET injection (0.66 +/- 0.02 at 2 minutes to 0.73 +/- 0.01 at 10 minutes; P < .01). Redistribution was nearly complete by 120 minutes (defect ratio = 0.87 +/- 0.03; P < or = .01 vs 2 minutes). Lung activity fell significantly during the first 10 minutes from a heart/lung activity ratio of 1.07 +/- 0.05 (2 minutes) to 1.44 +/- 0.09 (10 minutes; P < or = .01). CONCLUSION: Initial stress Tc-99m-N-NOET images should be acquired within 10 minutes after injection, whereas delayed images can be obtained as early as 2 hours later. Lung activity clears rapidly, permitting acquisition of good-quality poststress cardiac images. These Tc-99m-N-NOET uptake and redistribution kinetics after vasodilator stress provide important information for designing clinical imaging protocols for optimal identification of inducible ischemia.     

Burden of myocardial damage in cardiac allograft rejection: Scintigraphic evidence of myocardial injury and histologic evidence of myocyte necrosis and apoptosis

BACKGROUND: Because myocardial damage determines morbidity and outcomes in heart transplant rejection, assessment of total burden of myocardial damage is highly desirable. In addition to myocyte necrosis, programmed cell death, or apoptosis, has recently been shown to contribute to cardiac allograft rejection. In the present study, we noninvasively determined myocardial damage by antimyosin scintigraphy and compared it with necrotic and apoptotic myocardial damage in endomyocardial biopsy (EMB) specimens. METHODS AND RESULTS: Forty scintigraphic and histologic studies were simultaneously performed. Of these, 19 patients had no EMB evidence of allograft rejection (group I, International Society of Heart and Lung Transplantation [ISHLT] grade 0/4), 12 had mild rejection (group II, ISHLT grades 1A and 1B), and 9 had evidence of moderate allograft rejection (group III, ISHLT grades 2, 3A, and 3B). None of the biopsies demonstrated severe allograft rejection (ISHLT grade 4/4). The severity of global myocyte damage in 40 patients was assessed by antimyosin scintigraphy. Endomyocardial biopsies were performed in these patients within 48 hours of imaging study; biopsy specimens were characterized for presence of myocyte necrosis and apoptosis. Evidence of myocyte necrosis was observed in 9 (23%) of 40 EMB specimens. Nineteen EMB specimens of group I had no inflammation and no myocyte necrosis, 12 of group II specimens showed interstitial mononuclear cell infiltration (only) but no myocyte necrosis, and all 9 of group III specimens had evidence of cellular infiltration and myocyte damage. Myocyte necrosis was assessed by hematoxylin-eosin and trichrome staining of EMB specimens. On the other hand, apoptosis of myocytes, as assessed by TUNEL staining of DNA fragments, was seen in 22 (55%) of the 40 biopsy specimens: 47%, 58%, and 67% in groups I, II and III, respectively. Abnormal antimyosin scan findings, indicating presence of myocardial damage, were observed in 9 of the 19 patients in group I and in all patients in groups II and III. Although positive antimyosin scan results in group III patients are concordant with the presence of histologic myocardial necrosis, myocardial uptake of antimyosin antibodies in groups I and II (no apparent myocyte damage at light microscopic examination) could reflect either sampling error of the biopsy or ongoing apoptotic myocyte damage. CONCLUSIONS: Apoptosis of myocytes is frequently observed during cardiac allograft rejection. The presence of apoptotic myocytes in the absence of histologic rejection activity in patients with antimyosin uptake suggests that apoptosis could be an additional mechanism of transplant-associated myocardial damage.     

Cardiac transplantations in dogs: evaluation with MR

To assess the potential of magnetic resonance (MR) imaging as an early predictor of cardiac transplant rejection, electrocardiogram-gated (ECG-gated) MR imaging was performed in 12 dogs with heterotopic cardiac transplants. Twenty-two examinations were performed in vivo, and ten postmortem examinations were performed immediately after the dogs were killed. Examinations were performed from 3 days to 14 weeks after transplantation. A 0.35-T superconducting magnet was used with the spin-echo pulse sequence. There was a significant increase (P less than .02 to P less than .001) in T2 relaxation times and intensity values for the transplanted hearts compared with native hearts at all time intervals after transplantation. T1 relaxation times of native and transplanted hearts showed no significant difference on the in vivo ECG-gated studies. However, T1 values calculated on post-mortem studies were significantly longer (P less than .005) in the transplanted compared with the native hearts. With longer pulse repetition and echo delay times, there was an increase in the contrast between the rejecting transplanted heart and the native heart. Thus, ECG-gated MR imaging using the spin-echo technique displays cardiac allograft rejection in vivo. The rejected myocardium in vivo is characterized by a prolonged T2 relaxation time.     

核医学显像评估生殖与性功能障碍

生殖道是一个复杂的解剖器官,它同时具有内分泌学和解剖学上的功能特征。核医学在检查生殖和性功能方面有一定价值,包括男性睾丸和阴茎海绵体的灌注情况,女性输卵管的传输情况及亚临床型精索静脉曲张。这些检查方法的成功应用证实了它们具有重要的临床实用价值。     

Nitrate-augmented myocardial imaging for assessment of myocardial viability

²⁰¹Tl myocardial perfusion imaging is presently done by several possible strategies. Stress/delayed redistribution, stress/redistribution/reinjection, and rest/redistribution imaging can be useful in the clinical assessment of myocardial viability. Unfortunately, the extent of myocardial viability may still be underestimated even by ²⁰¹Tl reinjection imaging, compared with ¹⁸F-fluorodeoxyglucose positron emission tomography. ^99mTc-labeled sestamibi imaging provides results similar to those of ²⁰¹Tl imaging in the detection of coronary artery disease, but several previous studies suggest that stress/rest ^99mTc-labeled sestamibi imaging significantly underestimates myocardial viability. Recently it has been reported that the administration of nitrates, before ²⁰¹Tl reinjection, improves detection of defect reversibility. Several studies also suggested that administration of nitrates before the injection of ^99mTc-labeled sestamibi significantly improved detection of reversibility with this agent, whereas additional studies showed further that this combination improves the predictive accuracy for recovery of left ventricular function and perfusion after coronary revascularization, compared with a standard rest ^99mTc-labeled sestamibi study. Nitrate administration before the injection of ²⁰¹Tl and ^99mTc-labeled sestamibi may thus be a potentially attractive alternative for the evaluation of myocardial viability. Although the available results are encouraging, further studies are needed to evaluate the clinical value of ²⁰¹Tl and ^99mTc-labeled sestamibi imaging, in combination with nitrates, for predicting recovery of left ventricular dysfunction.