Assessment of myocardial perfusion by dynamic O-15-labeled water PET imaging: Validation of a new fast factor analysis

Background  Factor analysis (FA) is an established method for separating myocardium from blood pool by use of oxygen 15-labeled water and positron emission tomography for analyzing myocardial blood flow (MBF). Conventional FA methods generating images from sinograms (sinoFA) are time-consuming, whereas FA can be performed on the reconstructed images (reconFA) in a fraction of time. We validated the MBF values obtained by reconFA versus sinoFA. Methods and Results  In 23 volunteers (mean age, 26.6±3.4 years) MBF was calculated from sinoFA and reconFA and blindly reanalyzed 1 month later by the same observer. Intraobserver agreement and reconFA-versus-sinoFA agreement were assessed according to Bland and Altman (BA). Reproducibility proved excellent for global sinoFA (r=0.968; P<.001; BA limits, −0.617 to 0.676 mL·min⁻¹·g⁻¹) and slightly superior for reconFA (r=0.979; P<.001; BA limits, −0.538 to 0.558 mL·min⁻¹·g⁻¹), with wider limits of agreement for segmental MBF from sinoFA (r=0.777; P<.001; BA limits, −1.676 to 1.656 mL·min⁻¹·g⁻¹) and reconFA (r=0.844; P<.001; BA limits, −1.999 to 1.992 mL·min⁻¹·g⁻¹). In addition, sinoFA and reconFA showed excellent correlation (r=0.975, P<.001) and agreement (BA limits, −0.528 to 0.648 mL·min⁻¹·g⁻¹) for global and segmental values (r=0.955; P<.001; BA limits, −1.371 to 1.491 mL·min⁻¹·g⁻¹). Conclusions  Use of reconFA allows rapid and reliable quantitative MBF assessment with O-15-labeled water. This study was supported by a grant from the Swiss National Science Foundation (professorship grant PP00A-114706).     

Attenuation correction of myocardial SPECT perfusion images with low-dose CT: evaluation of the method by comparison with perfusion PET.

In cardiac SPECT, specificity is significantly affected by artifacts due to photon absorption. As the success of attenuation correction depends mainly on high-quality attenuation maps, SPECT low-dose CT devices are promising. We wanted to evaluate the usefulness of a SPECT low-dose CT device in myocardial perfusion scintigraphy. For the evaluation of attenuation correction systems, primarily comparisons with coronary angiography are used. Because the comparison of a method showing myocardial perfusion with an investigation displaying the morphology of vessels yields some difficulties, we chose perfusion PET with (13)N-ammonia as the reference method. METHODS: We prospectively analyzed 23 patients (6 women, 17 men) with known or suspected coronary artery disease. Rest studies and studies under pharmacologic stress with adenosine were performed. After simultaneous injection of (13)N-ammonia and (99m)Tc-sestamibi, a dynamic PET acquisition was started. The SPECT study was performed about 2 h later. Based on 20-segment polar maps, SPECT with and without attenuation correction was compared with PET-derived perfusion values and ammonia uptake values. The PET uptake images were also smoothed to adjust their resolution to the resolution of the SPECT images. RESULTS: The concordance of SPECT and PET studies was improved after attenuation correction. The main effect was seen in the inferior wall. Especially in the apex and anterolateral wall, there were differences between SPECT and PET studies not attributable to attenuation artifacts. Because these differences diminished after smoothing of the PET studies, they might be due to partial-volume effects caused by the inferior resolution of the SPECT images. CONCLUSION: The x-ray-derived attenuation correction leads to SPECT images that represent myocardial perfusion more accurately than nonattenuation-corrected SPECT images. The benefit of the method is seen primarily in the inferior wall. The low resolution of the SPECT system may lead to artifacts due to partial-volume effects. This phenomenon must be considered when perfusion PET is used as a reference method to investigate the effect of attenuation correction.     

Combined evaluation of regional coronary artery calcium and myocardial perfusion by 82Rb PET/CT in predicting lesion-related outcome

European Journal of Nuclear Medicine and Molecular Imaging - Cardiac imaging with positron emission tomography/computed tomography (PET/CT) allows measurement of coronary artery calcium (CAC),...     

A comparative regional analysis of coronary atherosclerosis and calcium score on multislice CT versus myocardial perfusion on SPECT.

For the noninvasive evaluation of coronary artery disease (CAD), both multislice CT and gated SPECT are available. How these 2 modalities relate, however, is yet unclear. The purpose of this study was to perform a head-to-head comparison of the results of multislice CT and gated SPECT on a regional basis (per vessel distribution territory) in patients with known or suspected CAD. METHODS: One hundred forty patients underwent both multislice CT for coronary calcium scoring and coronary angiography and gated SPECT for myocardial perfusion imaging. The coronary calcium score was determined for each coronary artery. Coronary arteries on multislice CT angiography were classified as having no CAD, insignificant stenosis (<50% luminal narrowing), significant stenosis, or total or subtotal occlusion (>/=90% luminal narrowing). Gated SPECT findings were classified as normal or abnormal (reversible or fixed defects) and were allocated to the territory of one of the various coronary arteries. RESULTS: In coronary arteries with a calcium score of 10 or less, the corresponding myocardial perfusion was normal in 87% (n = 194/224). In coronary arteries with extensive calcifications (score > 400), the percentage of vascular territories with normal myocardial perfusion was lower, 54% (n = 13/24). Similarly, in most of the normal coronary arteries on multislice CT angiography, the corresponding myocardial perfusion was normal on SPECT (156/175, or 89%). In contrast, the percentage of normal SPECT findings was significantly lower in coronary arteries with obstructive lesions (59%) or with total or subtotal occlusions (8%) (P < 0.01). Nonetheless, only 48% of vascular territories with normal perfusion corresponded to normal coronary arteries on multislice CT angiography, whereas insignificant and significant stenoses were present in, respectively, 40% and 12% of corresponding coronary arteries. CONCLUSION: Although a relationship exists between the severity of CAD on multislice CT and myocardial perfusion abnormalities on SPECT, analysis on a regional basis showed only moderate agreement between observed atherosclerosis and abnormal perfusion. Accordingly, multislice CT and gated SPECT provide complementary rather than overlapping information, and further studies should address how these 2 modalities can be integrated to optimize patient management.     

Dipyridamole, cold pressor test, and demonstration of endothelial dysfunction: a PET study of myocardial perfusion in diabetes.

Much evidence suggests endothelial dysfunction to be present in non-insulin-dependent diabetes mellitus (NIDDM) and to be important for the development of myocardial ischemia. Endothelial function in the coronary vessels may be studied in various ways. We compared the effect of cold pressor testing (CPT) with that of dipyridamole, a pharmacologic vasodilator, on coronary blood flow (CBF) measured by PET in NIDDM patients and healthy volunteers. In addition, we studied the effect of acute angiotensin-converting enzyme (ACE) inhibition on the flow response. METHODS: Ten NIDDM patients and 10 control subjects participated. Myocardial perfusion was determined at baseline, during CPT, and after dipyridamole infusion by PET using intravenous (13)N-ammonia. RESULTS: Resting CBF was similar in NIDDM patients and in control subjects. CPT increased CBF by 20% in the control group, whereas no increase was observed in the patients. After dipyridamole infusion, CBF increased 2- to 3-fold in patients and 3- to 4-fold in control subjects. The increase and maximal CBF were significantly higher in control subjects than in patients. During ACE-inhibitor infusion, which had no influence on resting CBF in patients or control subjects (n = 5), CPT increased CBF by 14% in the NIDDM group. After dipyridamole, CBF increased 3- to 4-fold in both groups. The increase in CBF and maximal CBF in the 2 groups were not different during ACE-inhibitor infusion. CONCLUSION: In these NIDDM patients without evidence of epicardial coronary disease, endothelial dysfunction is strongly suggested by an impaired increase in CBF both to dipyridamole and to CPT. This dysfunction was reversed by infusion of an ACE inhibitor. Although ACE inhibition during CPT did induce significant increases in CBF in the patients, the changes during ACE inhibition were small compared with the dipyridamole response, and the absence of CBF increase during CPT in 3 of the 10 control subjects further limits the value of CPT for the study of coronary endothelial dysfunction.     

PET for evaluation of differential myocardial perfusion dynamics after VEGF gene therapy and laser therapy in end-stage coronary artery disease.

The purpose of this study was to appraise the value of PET in the assessment of the effect of supposedly proangiogenic new therapies such as gene therapy with vascular endothelial growth factor (VEGF) gene and endomyocardial laser therapy. METHODS: Thirty-five patients with end-stage coronary artery disease and class III (Canadian Cardiovascular Society) angina were included. Myocardial ischemia was evaluated with dipyridamole PET scanning and exercise tolerance with bicycle ergometry. Ten patients were treated with naked plasmid DNA encoding for human VEGF165 (VEGF) and 12 patients were treated with laser therapy (direct myocardial revascularization [DMR]) using an electromechanical mapping system. Thirteen patients were treated with standard medical therapy (control). RESULTS: In both active treatment groups, angina was reduced in most subjects, except in 2 VEGF and 5 DMR patients. In the control group, no improvement in anginal classification was found, except in 3 subjects. On the PET scan, solely in the VEGF group, the stress perfusion was significantly improved (from 57 +/- 33 to 81 +/- 55 mL/min/100 g; P = 0.031). Furthermore, in the VEGF group, the number of ischemic segments was reduced from 274 +/- 41 to 234 +/- 48 segments (P = 0.004) but not in the DMR group (from 209 +/- 43 to 215 +/- 52 segments) or in the control group (from 218 +/- 18 to 213 +/- 28 segments). Bicycle exercise duration showed slight nonsignificant changes in the VEGF group (from 3.6 +/- 2.0 to 4.6 +/- 2.1 min), in the DMR group (from 5.1 +/- 1.5 to 4.7 +/- 1.3 min), and in the control group (from 3.3 +/- 1.8 to 3.5 +/- 2.3 min). CONCLUSION: PET showed that intramyocardial gene therapy with the human VEGF165 gene in contrast to laser DMR treatment effectively reduces myocardial ischemia.     

Diastolic dysfunction in patients with systemic sclerosis detected by gated myocardial perfusion SPECT: an early sign of cardiac involvement.

Diagnosis of cardiac involvement is important for the management of patients with systemic sclerosis (SSc). This study was undertaken to determine the significance of gated myocardial perfusion SPECT in patients with SSc and whether diastolic function measured by gated SPECT is an early sign of cardiac complications. METHODS: Thirty-four patients with SSc and 16 control patients were studied using exercise nongated and resting gated myocardial perfusion SPECT. The SSc was classified by the modified Rodnan total skin score (TSS) into high-TSS (score > or = 10; n = 18) and low-TSS (score < 10; n = 16) groups. Gated SPECT was performed using 99mTc-methoxyisobutylisonitrile with 16 frames per cardiac cycle and quantitatively analyzed by QGS software and Fourier filtering of the volume curve. The parameters of ejection fraction (EF), peak filling rate (PFR), one-third mean filling rate, and time to PFR (TPFR) were calculated. RESULTS: A slight perfusion abnormality was observed in four and five patients in the low-TSS and high-TSS groups, respectively (not statistically significant). A decreased resting EF less than 55% was found in no and two patients in the low-TSS and high-TSS groups, respectively. TPFR was 166 +/- 22, 168 +/- 38, and 216 +/- 82 ms (P = 0.05, high-TSS group versus low-TSS group; P = 0.04, control group versus high-TSS group) and TPFR/R-R interval was 0.18 +/- 0.02, 0.19 +/- 0.04, and 0.26 +/- 0.09 (P = 0.01, high-TSS group versus low-TSS group; P = 0.005, control group versus high-TSS group) for the control, low-TSS, and high-TSS groups, respectively. CONCLUSION: Diastolic function can be evaluated by gated myocardial perfusion SPECT. Significant diastolic abnormalities were shown even in patients with normal perfusion and systolic function and were related to the severity of SSc.     

Quantitative analysis of regional motion and thickening by gated myocardial perfusion SPECT: normal heterogeneity and criteria for abnormality.

Quantitation of regional myocardial function is valuable in patients with coronary artery disease. This study assessed normal heterogeneity and developed and validated normal limits for quantitative regional motion and thickening by gated myocardial perfusion SPECT. METHODS: Patients underwent rest (201)Tl/exercise (99m)Tc-sestamibi gated SPECT. Reference values of motion and thickening for 20 myocardial segments were obtained in 105 patients with <5% likelihood of coronary disease (low-likelihood group). Criteria for abnormality of motion and thickening were defined for each segment, using receiver operator characteristic analysis, in 101 patients with coronary disease (training group). Semiquantitative visual interpretation was used as the gold standard. These criteria were prospectively validated in 100 patients (validation group). Criteria for grading motion and thickening abnormalities by severity levels were also defined and validated. RESULTS: Normal thickening decreased substantially along the longitudinal axis of the left ventricle, from 69% +/- 13% at the apex to 25% +/- 11% at the basal segments, whereas normal motion varied within the same ventricular plane. Validation of the criteria for abnormality yielded high accuracy in the detection of motion abnormalities (sensitivity, 88%; specificity, 92%) and thickening abnormalities (sensitivity, 87%; specificity, 89%). Quantitative motion and thickening segmental scores showed good agreement with visual scores. CONCLUSION: Normal regional myocardial contraction by gated myocardial perfusion SPECT is characterized by a substantial apex-to-base decline in thickening and by circumferential heterogeneity in endocardial motion. The assignment of segment-specific threshold values for defining motion and thickening abnormalities provided reasonably accurate identification and grading of regional myocardial dysfunction.     

门控心肌灌注断层显像相位分析评价健康人左室心肌收缩同步性

目的 应用美国Cedars-Sinai定量门控心肌断层显像(QGS)软件的相位分析技术定量分析健康人左室心肌收缩同步性.方法 对74名健康人[男41名,女33名,平均年龄(60±13)岁]进行运动-静息99Tcm-MIBI G-MPI.应用QGS软件对重建后的静息图像进行自动分析,获得左室心肌收缩同步性参数:相位直方图带宽(BW)和相位标准差(SD),比较不同性别及年龄组(＜60岁组,36名;≥60岁组,38名)间左室心肌收缩同步性的差别.测量左室17个节段的起始相位角度,确定左室心肌最早收缩部位,简单随机抽样选择40名受检者评价QGS软件相位分析技术在同一操作者和不同操作者间的重复性.数据分析采用两样本t检验和直线相关分析.结果 74名受检者左室BW和SD值分别为(37.22±11.71)°和(11.84±5.39)°.男性和女性BW及SD值差异均无统计学意义[BW:(36.00±9.70)°和(38.73±13.84)°;SD:(11.88±5.56)°和(11.79±5.26)°;t=0.96和-0.07,均P＞0.05).年龄≥60岁组较年龄＜60岁组BW宽[(39.95±12.65)°和(34.33±10.00)°;t=-2.11,P＜0.05];但2年龄组间SD差异无统计学意义[(11.18±4.31)°和(12.54±6.33)°;t=1.08,P＞0.05].74名受检者中,54名(73％)左室心肌收缩从基底部向心尖部扩散,仅20名(27％)由心尖部向基底部扩散.同一操作者2次操作及2名操作者间相位分析结果均相关(r=0.867～0.906,均P＜0.001).结论 健康人左室心肌收缩同步性良好,不同性别间无明显差异,年龄＜60岁者心肌收缩同步性较≥60岁者更好.QGS心脏相位分析软件是可定量评价左室心肌收缩同步性的工具,且重复性好.     

Comparsion with myocardial perfusion MRI and myocardial perfusion SPECT in the diagnostic performance of coronary artery disease: a meta-analysis

We compared the diagnostic abilities of stress myocardial perfusion MRI (myocardial perfusion MRI) and myocardial perfusion SPECT, using a meta-analysis method. We investigated the diagnostic abilities of MRI and SPECT in similar subject groups in reports written in English or Japanese. The reports to be used for analysis were selected according to a "screening standard," which was established in advance. After consolidating the data from the selected reports, we compared (1) the integrated odds ratio, (2) the point estimation values of sensibility/specificity, and (3) the summary ROC curve. For the analysis, six reports were selected (subjects: 153, coronary-artery target sites: 447). Meta-analysis revealed that the diagnostic ability of myocardial perfusion MRI was superior to that of myocardial perfusion SPECT regarding each of the parameters (1)-(3). This is considered to be supportive evidence of the usefulness of myocardial perfusion MRI.     

Cardiac imaging and safety evaluation of BMS747158, a novel PET myocardial perfusion imaging agent,in chronic myocardial compromised rabbits

Background  

BMS747158 labeled with ¹⁸F is being developed for PET myocardial perfusion imaging. Imaging studies showed clear detection of necrotic tissue in acute myocardial infarcted (MI) animals and a good safety profile in normal animals. This study evaluated BMS747158 imaging and cardiovascular safety in a rabbit model of chronic MI with cardiac compromise.     

Automatic quantification of myocardial perfusion stress-rest change: a new measure of ischemia.

In myocardial perfusion SPECT (MPS), ischemia is typically quantified as the difference between stress and rest defect sizes obtained by separate comparisons with stress and rest normal limits. Such an approach is not optimal because images are not compared directly with each other and a complex set of stress and rest normal limits is required. METHODS: We developed a fully automatic technique to quantify stress-rest change. We applied it to 204 patients whose SPECT images were acquired using a same-day dual-isotope (99m)Tc/(201)Tl protocol and on whom coronary angiography had been performed. A 10-parameter registration of rest and stress images was performed by an iterative search of best translational, rotational, scaling, and optimal stress-rest count normalization parameters. Identical stress-rest 3-dimensional left ventricle (LV) contours were automatically derived from stress images. Integrated deficit counts (normalized rest-stress) within the LV volume were derived from registered image pairs. A global measure of ischemia (ISCH) was calculated as the ratio of the total deficit stress LV counts to the total rest LV counts. RESULTS: Registration and derivation of quantitative measures were fully automatic. The average processing time was <40 s on a 2-GHz processor. When compared for prediction of stenosis, the area under the receiver operating characteristic curve (0.88 +/- 0.03) was significantly better for ISCH than that obtained by existing quantitative approaches, which use reference databases (0.80-0.82 +/- 0.03). The normalized stress-rest change could be visualized and localized directly on raw patient images using overlay display. CONCLUSION: Automatic stress-rest MPS image registration allows a direct estimation of ischemia from SPECT that does not require comparisons with normal limits.     

Typical chest pain and normal coronary angiogram: cardiac risk factor analysis versus PET for detection of microvascular disease.

Angiography of patients with typical chest pain reveals normal epicardial coronary arteries in about 20%. Coronary flow reserve (CFR) determination is an elaborate, but helpful, task, as only the evidence of microvascular disease enables appropriate therapy. We prospectively evaluated the incidence of a dysfunctional microcirculation and searched for predictive parameters of a reduced CFR. METHODS: In 79 consecutive patients (52 females, 27 males) with typical angina and a normal angiogram and 10 control subjects (6 females, 4 males), CFR was measured by 13N-ammonia rest/dipyridamole PET and correlated with clinical parameters individually and summarized as the number of risk factors (NRF) using an elaborated cardiac risk factor score. RESULTS: Sixty-five percent of patients had a reduced CFR (CFR < 2.5). CFR correlated with NRF (r = 0.55, P < 0.001), systolic blood pressure (r = 0.46, P < 0.001), interventricular septal thickness (r = 0.33, P < 0.01), and age (r = 0.25, P = 0.02). Eighty-five percent of patients with a high risk factor score (NRF > or = 5) had a reduced CFR. In contrast, 100% of our patients with a low risk factor score (NRF < 2) presented a normal CFR. In total, 55% of our patients could be allocated to either one of these groups. CONCLUSION: In about two thirds of patients, anginal pain can be explained by a reduced CFR. Risk factors have a cumulative negative effect on CFR. A clinical cardiac risk factor analysis enables estimation of individual probability of microvascular dysfunction in a significant proportion of these patients. However, CFR measurements are recommended for those with an intermediate NRF.     

99Tcm-MIBI心肌灌注显像对代谢综合征患者并发冠心病的评价

目的 探讨核素心肌灌注显像对代谢综合征患者并发冠心病的诊断价值.方法 回顾性分析251例[男179例,女72例,年龄(59±10)岁]代谢综合征患者99Tcm-甲氧基异丁基异腈(MIBI)心肌灌注显像的结果,与冠状动脉造影进行比较,计算99Tc-MIBI心肌灌注显像诊断冠心病的灵敏度、特异性和准确性.结果 在251例代谢综合征患者中,163例(65%)患者冠状动脉造影示有狭窄病变,99Tcm-MIBI心肌灌注显像检出心肌缺血或心肌梗死116例;88例冠状动脉造影阴性患者中,82例心肌灌注显像结果正常;99Tcm-MIBI心肌灌注显像诊断冠心病的灵敏度为71%(116/163),特异性为93%(82/88),阳性预测值为95%(116/122),阴性预测值为64%(82/129),准确性为79%(198/251).诊断单支、双支和三支冠状动脉病变患者的灵敏度分别为58%(36/61),61%(22/36)和87%(57/66).结论 99Tcm-MIBI心肌灌注显像对检测代谢综合征患者有无并发冠心病有重要的应用价值.     

Left ventricular early myocardial dysfunction after chronic misuse of anabolic androgenic steroids: a Doppler myocardial and strain imaging analysis

Background

Anabolic androgenic steroids (AAS) are sometimes used by power athletes to improve performance by increasing muscle mass and strength. Recent bioptical data have shown that in athletes under the pharmacological effects of AAS, a focal increase in myocardial collagen content might occur as a repair mechanism against myocardial damage.

Objective

To investigate the potential underlying left ventricular myocardial dysfunction after chronic misuse of AAS in athletes by use of Doppler myocardial imaging (DMI) and strain rate imaging (SRI).

Methods

Standard Doppler echocardiography, DMI, SRI and ECG treadmill test were undertaken by 45 bodybuilders, including 20 athletes misusing AAS for at least 5 years (users), by 25 anabolic‐free bodybuilders (non‐users) and by 25 age‐matched healthy sedentary controls, all men. The mean (SD) number of weeks of AAS use per year was 31.3 (6.4) in users, compared with 8.9 (3.8) years in non‐users, and the mean weekly dosage of AAS was 525.4 (90.7) mg.

Results

The groups were matched for age. Systolic blood pressure was higher in athletes (145 (9) vs 130 (5) mm Hg) than in controls. Left ventricular mass index did not significantly differ between the two groups of athletes. In particular, both users and non‐users showed increased wall thickness and relative wall thickness compared with controls, whereas left ventricular ejection fraction, left ventricular end‐diastolic diameter and transmitral Doppler indexes were comparable for the three groups. Colour DMI analysis showed significantly lower myocardial early: myocardial atrial diastolic wave ratios in users at the level of the basal interventricular septum (IVS) and left ventricular lateral wall (p<0.01), in comparison with both non‐users and controls. In addition, in users, peak systolic left ventricular strain rate and strain were both reduced in the middle IVS (both p<0.001) and in the left ventricular lateral free wall (both p<0.01). By stepwise forward multivariate analyses, the sum of the left ventricular wall thickness (β coefficient = −0.32, p<0.01), the number of weeks of AAS use per year (β = −0.42, p<0.001) and the weekly dosage of AAS (β = −0.48, p<0.001) were the only independent determinants of middle IVS strain rate. In addition, impaired left ventricular strain in users was associated with a reduced performance during physical effort (p<0.001).

Conclusions

Several years after chronic misuse of AAS, power athletes show a subclinical impairment of both systolic and diastolic myocardial function, strongly associated with mean dosage and duration of AAS use. The combined use of DMI and SRI may therefore be useful for the early identification of patients with more diffused cardiac involvement, and eventually for investigation of the reversibility of such myocardial effects after discontinuation of the drug.Haemodynamic overload due to long‐term training usually involves both left and right ventricles, inducing changes in cardiac structure such as increases in internal cavity diameters, wall thickness and mass, usually described as “athlete''s heart”.^1,2,3,4,5,6In competitive athletes, left ventricular hypertrophy often mimics pathological conditions, and the distinction may have important implications, particularly in adulthood when practising regular physical activity.Anabolic androgenic steroids (AAS) are sometimes used by power athletes to improve performance by increasing muscle mass and strength.^7,8,9,10,11 AAS stimulate cellular protein synthesis through androgenic receptors and promote the growth of all organs that have receptors similar to those of androgens.^{12,13,14,15,16} The effects of the chronic assumption of AAS on human performance and on cardiovascular structures are subjects of intense debate. Recent bioptical data have shown that in athletes under the pharmacological effects of AAS, a focal increase in myocardial collagen content might occur as a repair mechanism against myocardial damage.¹⁰Although standard Doppler echocardiography has been widely used to distinguish athlete''s heart from pathological left ventricular hypertrophy, few echocardiographic reports have defined changes in left ventricular morphology and function determined by chronic misuse of AAS.^{17,18,19,20,21,22,23,24}Doppler myocardial imaging (DMI) and strain rate imaging (SRI) extend Doppler applications beyond the analysis of cardiac blood flows into the measurement of regional myocardial function.^25,26,27,28 Our previous reports have documented the usefulness of such techniques in identifying training influence on left ventricular myocardial longitudinal function, and in detecting differences of myocardial function in different kinds of pathological left ventricular hypertrophy.^29,30,31,32 However, no data are presently available about the possible effects of AAS misuse on left ventricular regional myocardial function in power athletes.The aim of this study was to investigate the potential underlying left ventricular myocardial dysfunction after chronic misuse of AAS in athletes by DMI and SRI.     

Reduced coronary flow reserve in patients with primary hyperparathyroidism: a study by G-SPECT myocardial perfusion imaging

Purpose

The mechanisms underlying increased cardiovascular risk in primary hyperparathyroidism (pHPT) have not been fully defined. Recently, this issue has become the subject of renewed interest due to the increasing evidence that the endothelium and vascular wall are targets for parathyroid hormone (PTH). The aim of this study was to measure regional coronary flow reserve (CFR) to determine whether the vascular damage induced by pHPT extends to affect the coronary microvascular function.

Methods

A total of 22 pHPT patients without a history of coronary artery disease and 7 age-matched control subjects were recruited. Dipyridamole myocardial blood flow (MBF) was assessed using ^99mTc-sestamibi by measuring first-transit counts in the pulmonary artery and myocardial count rate from G-SPECT images. Baseline MBF was estimated 2 h later according to the same procedure. Regional CFR was defined as the ratio between dipyridamole and baseline MBF using a 17-segment left ventricular model.

Results

Three pHPT patients showed reversible perfusion defects and were excluded from the analysis. In the remaining 19, CFR was significantly lower with respect to the control subjects (1.88?±?0.64 vs. 3.36?±?0.66, respectively; p?<?0.01). Moreover, patients studied for more than 28 months from pHPT diagnosis showed lower CFR values than the others (1.42?±?0.18 vs. 2.25?±?0.64, respectively; p?<?0.01). Consequently, the time from diagnosis to the nuclear study showed a reasonable correlation with the degree of CFR impairment (Spearman’s rho ?0.667, p?<?0.02).

Conclusion

pHPT is associated with a significant dysfunction of the coronary microcirculation. This disorder might contribute to the high cardiovascular risk of conditions characterized by chronic elevations in serum PTH levels.