Myocardial <Superscript>123</Superscript>I-metaiodobenzylguanidine imaging in hypertension and left ventricular hypertrophy

Sympathetic nervous system plays a pivotal role in essential hypertension and in the development of left ventricular hypertrophy. Moreover, cardiac sympathetic dys-regulation has been demonstrated as a key con-causal factor in the genesis and progression of pathologic conditions such as congestive heart failure and ischemic heart disease to which hypertension predisposes as a risk factor. However, despite its fundamental role in cardiac pathophysiology, the evaluation of cardiac sympathetic nervous system has never gained a wide clinical application, remaining mostly a research tool. In this context, nuclear imaging techniques are the only modalities to allow the direct evaluation of cardiac sympathetic nervous integrity, giving the chance to obtain objective measures of the sympathetic tone. This review, while summarizing the general profile of currently available tests for autonomic evaluation, focuses on ¹²³I-metaiodobenzylguanidine nuclear imaging as a preferential tool to assess cardiac sympathetic status. Specifically, the review discusses the available evidence on cardiac ¹²³I-metaiodobenzylguanidine scintigraphy in arterial hypertension and left ventricular hypertrophy and its diagnostic and prognostic potential in congestive heart failure and ischemic heart disease.     

MR imaging of pulmonary arterial hypertension and pulmonary emboli

Intraluminal signal in the pulmonary arteries on spin-echo, ECG-gated MR images is limited to the diastolic phase of the cardiac cycle in normal subjects. Initial experience has indicated that signal persisting during systole may be characteristic of slow blood flow associated with pulmonary arterial hypertension (PAH) or of thrombotic material secondary to pulmonary embolism. This study analyzes our cumulative experience (31 patients) with multiphasic, double spin-echo MR for assessing PAH and/or suspected pulmonary embolism. In PAH, the abnormal systolic signal showed an intensity increase from first to second echo. This pattern was observed in 92% of PAH patients, including 100% of patients with pulmonary systolic pressures greater than or equal to 80 mm Hg and 60% of patients with pressures less than 80 mm Hg. At any focus in the pulmonary arteries, such signal disappeared at some phase of the cardiac cycle. In patients with pulmonary embolism, signal from thrombus was fixed throughout the cardiac cycle and showed little or no increase in relative intensity change from first- to second-echo image. Using this guideline, MR made six confirmed positive and four confirmed negative diagnoses of proximal pulmonary embolism, while it failed to identify thrombus in the one patient with a peripheral pulmonary embolism. Intraluminal signal in the pulmonary arteries caused by PAH or pulmonary embolism can be differentiated in most instances using multiphasic, double spin-echo, ECG-gated MR. However, at its current stage of development, the procedure does not appear to be useful for the evaluation of peripheral pulmonary embolism.     

肺动脉高压病人左右心室心肌灌注储备与右心室功能及肺血流动力学之间的相关性

目的应用腺苷负荷MR心肌灌注成像评价肺动脉高压(PAH)病人右心室(RV)与左心室(LV)间心肌灌注储备与心室功能及肺血流动力学的关系。材料与方法本研究符     

特发性肺动脉高压与先天性心脏病相关肺动脉高压患者右心室心肌葡萄糖代谢的比较研究

目的 比较分析特发性肺动脉高压（IPAH）与先天性心脏病相关肺动脉高压（PAH-CHD）患者右心室心肌葡萄糖代谢的差异。 方法 选取2016年11月至2018年12月在中国医学科学院北京协和医学院阜外医院确诊的26例IPAH患者（IPAH组）[女性17例、男性9例,年龄（28.23±8.92）岁] 和16例PAH-CHD患者（PAH-CHD组） [女性10例、男性6例,年龄（29.19±10.62）岁]。所有患者均行动态18F-FDG PET心肌代谢显像,根据Patlak法计算得出右心室和左心室心肌葡萄糖利用率（rMGU）。显像后1周内患者接受右心导管检查,测定血流动力学指标。采用独立样本t检验比较2组的rMGU等指标;采用Pearson相关分析对2组患者右心室的rMGU与平均肺动脉压力（mPAP）或肺血管阻力的相关性进行分析。 结果 IPAH组与PAH-CHD组患者mPAP之间的差异无统计学意义 [（59.85±16.46） mm Hg 对（69.75±18.93） mm Hg,t=1.79,P=0.81]（1 mm Hg=0.133 kPa）。动态18F-FDG PET心肌代谢显像测得的2组患者右心室rMGU[（0.095±0.074） μmol·g−1·min−1 对（0.135±0.165） μmol·g−1·min−1]与左心室rMGU[（0.057±0.065） μmol·g−1·min−1 对（0.070±0.047） μmol·g−1·min−1] 之间的差异均无统计学意义（t=1.07, P=0.29;t=0.77,P=0.49）。IPAH组患者右心室的rMGU与mPAP存在正相关（r=0.420,P=0.033）,但PAH-CHD组患者右心室的rMGU与mPAP无相关性（r=0.016,P=0.953）。 结论 mPAP无差异的IPAH和 PAH-CHD患者右心室心肌葡萄糖代谢水平无明显差异。     

动态肺灌注显像评价特发性肺动脉高压的临床研究

目的 探讨动态PPI用于IPAH的临床应用价值.方法 2009年7月至2010年12月间20例经右心导管及肺动脉造影检查确诊为IPAH的连续病例和10名健康对照者,接受动态PPI.以双肺为ROI,得到时间-放射性曲线,计算显像剂从进入肺内到肺内放射性分布达到平衡的肺平衡时间(LET).组间比较采用t检验,LET与右心导管测得的血流动力学参数进行Pearson相关分析.结果 IPAH患者LET平均为(33.9 ±15.5)s,而健康对照组仅为(14.4±3.7)s,IPAH患者LET明显延长(t=5.340,P＜0.001).LET与mPAP、全肺阻力(TPR)间具有直线相关性(分别为r=0.566,P＜0.01和r=0.688,P＜0.05),与CI呈直线负相关(r=-0.480,P＜0.05).结论 动态PPI对于无创性评估IPAH血流动力学变化程度及右心功能具有一定的应用价值.     

Correlation between chest film and angiographic assessment of left ventricular size.

In 76 adult males quantitative angiographic measurements of left ventricular size were compared to 12 plain chest film measurements of heart size and shape. Of the 18 normal cases, only Rigler's B measurement correlated with left ventricular volume (r = .64). However, this correlation was not statistically significant. Of the 58 patients with isolated aortic valve disease, 19 had increased left ventricular mass (hypertrophy) and 39 had both increased left ventricular end-diastolic volume and mass (hypertrophy and dilatation). In the hypertrophy group, plain film heart volume was the most sensitive detector of an enlarged left ventricle (21% false negative rate) and correlated with left ventricular end-diastolic volume (r = .62). Using stepwise discriminant analysis, the combination of heart volume, leftness of the heart, apex position, and roundness of the left ventricle decreased the false negative rate to 5%. In the hypertrophy and dilatation group, plain film heart volume had the highest correlation with left ventricular volume and mass (r = .66) and a false negative rate of 8%. No single variable or combination of variables could usefully discriminate between the hypertrophy and hypertrophy and dilatation groups. These data support the conclusion that plain film heart volume is the best single measurement for detecting left ventricular enlargement.     

Interventricular septal configuration at mr imaging and pulmonary arterial pressure in pulmonary hypertension

PURPOSE: To investigate whether a relationship exists between septum shape and systolic pulmonary arterial pressure (PAP) in patients with pulmonary hypertension. MATERIALS AND METHODS: Study protocol was approved by institutional ethics review committee; all patients gave informed consent. Right-sided heart catheterization with vasodilator testing was performed in 39 adult subjects suspected of having pulmonary hypertension. There were 11 men and 28 women, aged 21-75 years (mean, 46 years). Only two patients showed favorable response to vasodilators, defined by a decrease in PAP of more than 20%. Synchronous right- and left-ventricular pressure measurements and four-chamber magnetic resonance (MR) imaging were used to identify timing of maximal leftward ventricular septal bowing within cardiac cycle. Septal bowing was evaluated with MR, measured on short-axis cine heart images, and expressed as curvature (reciprocal of radius). Curvature was quantified on one image (the one that showed the most severe distortion of normal septal shape). The relationship between systolic PAP and septal curvature was tested with linear regression analysis. P <.05 was considered to indicate a statistically significant difference. RESULTS: Of 39 subjects, 37 had pulmonary hypertension. Maximal distortion of normal septal shape was found during right ventricular relaxation phase. Systolic PAP was proportional to septal curvature: r=0.77 (P < .001), slope=-114.7, and intercept=67.2. In the two vasodilator responsive subjects, a significant reduction of leftward ventricular septal bowing was observed in response to reduction of right ventricular pressure. CONCLUSION: In 37 patients with pulmonary hypertension, systolic PAP higher than 67 mm Hg may be expected when leftward curvature is observed.     

Central thrombi in pulmonary arterial hypertension detected by MR imaging

Differentiation of thrombi from slow flow in the pulmonary arteries, sometimes observed in the presence of pulmonary arterial hypertension, can be equivocal. Magnetic resonance (MR) imaging was performed in a patient with chronic pulmonary thromboembolism and pulmonary arterial hypertension using an electrocardiographically gated technique that allowed visualization of the pulmonary arteries at the end of diastole and multiple times during systole. These images were compared with those of a patient with primary pulmonary hypertension and those of healthy subjects. Thrombi were discrete structures, seen throughout the cardiac cycle on both the first and second spin-echo images, and decreased in signal intensity on the second image. Slow flow increased in signal intensity and changed in structure during the cardiac cycle and was seen best on the second image. MR may play an important role in excluding large central thrombi as the cause of pulmonary arterial hypertension. It is a noninvasive method for defining pulmonary arterial wall thickness and for direct visualization of chronic pulmonary thrombus.     

123I-MIBG myocardial imaging in hypertensive patients: Abnormality progresses with left ventricular hypertrophy

Twenty-seven patients with essential hypertension were prospectively studied with¹²³I-labeled metaiodobenzyl-guanidine (¹²³I-MIBG) to assess the presence and location of impaired sympathetic innervation in hypertrophied myocardium. Thirteen patients had left ventricular hypertrophy on echocardiography, and 14 had normal echocardiograms. The wash-out ratio of¹²³I-MIBG in these two groups did not differ significantly (35.3 ± 6.1 and 35.4 ± 5.1) but was higher than in control subjects (29.4 ± 6.7). The delayed heart-to-mediastinum count ratio was lower in the patients with hypertrophy than in the patients without hypertrophy (1.93 ± 0.28 and 2.22 ± 0.21; p < 0.05) and the control subjects (1.93 ± 0.28 and 2.33 ± 0.25; p < 0.05). On SPECT imaging, abnormalities in segmental uptake were frequent at the posterior and postero-lateral wall in both groups, although the hypertrophic group had more significant impairment. Our results lead to the hypothesis that hypertension in more advanced stages may be associated not only with hypertrophic changes but also with more advanced regional impairment of cardiac sympathetic innervation.     

Glomerular filtration rate and the kinetics of 123I-metaiodobenzylguanidine

We have recently reported evidence that the calcium antagonist nifedipine can improve the tumour retention of ¹³¹I-metaiodobenzylguanidine (¹³¹I-MIBG) in patients with malignant phaeochromocytoma. During studies of the pharmacological modification of tumour MIBG kinetics, it is important to distinguish clearly between a direct effect on MIBG cellular retention by a pharmaceutical, and secondary effects due, for example, to a change in glomerular filtration rate (GFR). In order to provide the fundamental kinetic data required for the numerical modelling of the effect of nifedipine on tumour MIBG kinetics, we have investigated the influence of GFR on MIBG plasma and renal kinetics. The ¹²³I-MIBG plasma curve and MIBG renal plasma clearance rate were studied in ten patients, ranging from subjects without biochemical or scintigraphic evidence of phaeochromocytoma to individuals with widely disseminated metastatic disease. GFR was measured using the ^99mTc-DTPA plasma clearance method. In four cases, the studies were repeated with the patients taking oral nifedipine. Statistically significant correlations were found between GFR and the MIBG plasma concentration, MIBG renal plasma clearance rate and the early (0 to 5 min) renal excretion of MIBG. The data permit the evaluation of the plasma integral during the first few min following bolus injection, a quantity important in the numerical modelling of tumour kinetics. GFR was found to have a major influence on whole-body MIBG kinetics, but there was also evidence of the effect of the metastatic tumour burden.     

CT肺动脉栓塞指数与右心功能及动脉血气分析指标的相关性研究

目的：通过CT肺动脉栓塞指数(PAOI)与右心功能参数及动脉血气分析指标的相关性研究,探讨 CT PAOI 评价肺栓塞(PE)病情严重程度的价值。方法整理本院进行CT肺动脉造影(CTPA)检查并确诊的70例 PE患者的 CT PAOI、右心功能参数及动脉血气分析指标,使用Spearman等级相关系数评价PAOI和右心室/左心室最大短轴直径比(RVd/LVd)、主肺动脉直径(MPAd)、上腔静脉直径(SVCd)、动脉氧分压(PaO2)、动脉二氧化碳分压(PaCO2)、血氧饱和度(SaO2)、肺泡-动脉氧分压差(P(A-a)O2)之间的相关性。结果 PAOI与PaO2呈负相关,相关系数为-0.442;PAOI与RVd/LVd、WPAd、SVCd及P(A-a)O2呈正相关,相关系数介于0.163~0.675之间;PAOI与 SaO2不相关。结论 CT PAOI可以用来评估PE的严重程度,但与患者临床病情严重程度不完全一致。     

Glomerular filtration rate and the kinetics of 123I-metaiodobenzylguanidine

We have recently reported evidence that the calcium antagonist nifedipine can improve the tumour retention of 131I-metaidobenzylguanidine (131I-MIBG) in patients with malignant phaeochromocytoma. During studies of the pharmacological modification of tumour MIBG kinetics, it is important to distinguish clearly between a direct effect on MIBG cellular retention by a pharmaceutical, and secondary effects due, for example, to a change in glomerular filtration rate (GFR). In order to provide the fundamental kinetic data required for the numerical modelling of the effect of nifedipine on tumour MIBG kinetics, we have investigated the influence of GFR on MIBG plasma and renal kinetics. The 123I-MIBG plasma curve and MIBG renal plasma clearance rate were studied in ten patients, ranging from subjects without biochemical or scintigraphic evidence of phaeochromocytoma to individuals with widely disseminated metastatic disease. GFR was measured using the 99mTc-DTPA plasma clearance method. In four cases, the studies were repeated with the patients taking oral nifedipine. Statistically significant correlations were found between GFR and the MIBG plasma concentration. MIBG renal plasma clearance rate and the early (0 to 5 min) renal excretion of MIBG. The data permit the evaluation of the plasma integral during the first few min following bolus injection, a quantity important in the numerical modelling of tumour kinetics. GFR was found to have a major influence on whole-body MIBG kinetics, but there was also evidence of the effect of the metastatic tumour burden.     

Computed tomographic pulmonary angiography in the assessment of severity of chronic thromboembolic pulmonary hypertension and right ventricular dysfunction

Purpose

The aim was to investigate the role of computed tomographic pulmonary angiography (CTPA) in the assessment of severity and right ventricular function in chronic thromboembolic pulmonary hypertension (CTEPH).

Materials and methods

Clinical and radiological data of 56 patients with CTEPH January 2006–October 2009 were retrospectively reviewed in the present study. All patients received CTPA with a 64-row CT using the retrospective ECG-Gated mode before digital subtraction pulmonary angiography and right-heart catheterization. CTPA findings including Right Ventricular diameter (RVd) and left ventricular diameter (LVd) were measured at the end diastole. CT Pulmonary Artery Obstruction Indexes including Qanadli Index and Mastora Index were used in the assessment of severity of pulmonary arterial obstruction. Hemodynamic parameters and pulmonary hypertension classification were evaluated by right-heart catheterization in all patients. Right ventricular function was measured with echocardiography in 49 patients.

Results

Qanadli Index and Mastora Index respectively were (37.93 ± 14.74)% and (30.92 ± 16.91)%, which showed a significant difference (Z = −5.983, P = 0.000) and a good correlation (r = 0.881, P = 0.000). Neither Qanadli nor Mastora Index correlated with pulmonary hypertension classification (r = −0.009, P = 0.920) or New York Heart Association heart function classification (r = −0.031, P = 0.756). Neither Qanadli nor Mastora Index correlated with any echocardiographic right ventricular parameters (P > 0.05), while RVd/LVd by CTPA correlated with echocardiographic right ventricular functional parameters (P < 0.05). Both Qanadli (r = −0.288, P = 0.006) and Mastora Index (r = −0.203, P = 0.032) demonstrated a weakly negative correlation with SPO₂. CTPA findings correlated with hemodynamic variables. Backward linear regression analysis revealed that the RVd/LVd, Right Ventricular Anterior Wall Thickness (RVAWT), Main Pulmonary Artery trunk diameter (MPAd) were shown to be independently associated with mean Pulmonary Artery Pressure (mPAP) levels (model: r² = 0.351, P = 0.025; RVd/LVd: beta = 11.812, P = 0.000; RVAWT: beta = 2.426, P = 0.000; MPAd: beta = 0.677, P = 0.003).

Conclusion

Computed tomographic pulmonary angiography is a valuable tool to evaluate hemodynamics, right ventricular function of CTEPH, but neither Qanadli Index nor Mastora Index can reflect pulmonary arterial obstruction in CTEPH accurately.     

速度向量成像与组织多普勒技术评价高血压患者左室舒张功能的一致性研究

目的：分析速度向量成像（VVI）与组织多普勒（TDI）两种技术在评价原发性高血压患者左室舒张功能中的诊断一致性,进而探讨VVI技术评价左室舒张功能的可行性。方法：原发性高血压患者101例,分别用速度向量成像和组织多普勒两种技术测量二尖瓣环前壁、下壁、侧壁、间隔4个位点的舒张期运动参数作为评价左室舒张功能的指标,并将两种检查方法的诊断结果进行Kappa一致性检验。结果：VVI速度指标与TDI速度指标的一致性较好（大部分位点Kappa值〉0.75）,VVI应变率指标与TDI速度指标的一致性一般（0.50〈Kappa值〈0.70）。结论：VVI技术在评价高血压患者左室舒张功能中与TDI具有良好的一致性,可作为评价左室舒张功能的一种新方法。     

Concentration of 123I-metaiodobenzylguanidine in left and right liver lobes. Findings indicate regional differences in function in the normal liver

PURPOSE: Normal radioactivity in the liver is often shown to be higher in the left lobe than in the right lobe at clinical examination by single photon emission computed tomography (SPECT) with 123I-metaiodobenzylguanidine (123I-MIBG). Our objective was to determine whether this represents a pathological condition. MATERIAL AND METHODS: The distribution of 123I-MIBG in the liver was retrospectively studied in clinical patients who had normal CT examinations of the liver and spleen. In the SPECT sections of 27 123I-MIBG examinations, we determined the activity ratios between the left and right lobes. The control group comprised 33 examinations with (111)In-pentetreotide (OctreoScan) and 23 examinations with 99mTc-antigranulocyte antibody. RESULTS: The mean activity ratio between left and right lobes for 123I-MIBG was 1.24, and for (111)In-pentetreotide 0.87. These figures differed significantly both from each other and from 1.00. The mean ratio for 99mTc-antibody at the early examinations was 0.99, and at the late examinations 0.95. These figures differed significantly from the values for 123I-MIBG and (111)In-pentetreotide. CONCLUSION: The increased concentration of 123I-MIBG in the left lobe of the liver compared to the right lobe is a normal finding. The reason for this cannot be explained. The difference in the way in which the left and right lobes deal with the three radiopharmaceuticals is a new finding and indicates a regional difference in liver function that has not been reported previously.