多层螺旋CT与M型超声心动图评估左室功能的对照研究

目的：用多层螺旋CT（multi-detector row computed tomography,MRCT）测量并评估左室功能的各项参数,并与M型超声心动图测量得到的结果进行比较。方法：62位冠心病或可疑患有冠心病的患者（男性40人、女性22人,平均年龄64.2±11.1岁）在24h内接受回顾性心电门控16通道MRCT心脏增强扫描及心脏M型超声心动图检查。在GEAW4.1CT工作站上测量出每位患者的左室舒张末期容积（LVEDV）、左室收缩末期容积（LVESV）并根据公式（LVEDV-LVESV）/LVEDV×100%计算出左室射血分数（LVEF）,并用简单直线回归分别分析MRCT测量所得参数与M型超声心动图测得结果的相关性。结果：16层CT测得的LVEDV为125.4±62.1ml、LVESV为52.8±59.3ml、LVEF为62.9±13.4%,与M型超声心动图测量结果（Teichholz校正公式法）有很好的相关性〔LVEDV为112.8±49.7ml（r=0.826,P〈0.001）、LVESV为45.9±47.0ml（r=0.960,P〈0.001）、LVEF为64.8±13.9%（r=0.916,P〈O．001）]。结论：回顾性心电门控MRCT心脏增强扫描可以应用于临床心功能的评估诊断。     

Voxel-based morphometric comparison between early- and late-onset mild Alzheimer's disease and assessment of diagnostic performance of z score images

BACKGROUND AND PURPOSE: Voxel-based morphometry (VBM), used for detecting brain atrophy, permits comparison of local gray matter concentration at every voxel in an image between two groups. We sought to delineate the specific patterns of cerebral gray matter loss with regard to onset of Alzheimer's disease (AD) by using MR imaging and VBM and to evaluate the diagnostic performance of VBM with Z score images. METHODS: Two groups of 30 patients with mild AD of different ages of onset were examined. Mean ages in the early- and late-onset groups were 60.2 +/- 5.2 and 71.5 +/- 2.6 years, respectively. Control subjects were aged-matched healthy volunteers. Regions of gray matter loss in early- and late-onset AD were examined with VBM. Diagnostic performance of Z score images obtained with the VBM method was evaluated in patients and control subjects by calculating the area under the receiver operating characteristic curve (A(z)). RESULTS: Both AD groups had significantly reduced gray matter in the bilateral medial temporal regions. In addition, the early-onset group had more severe gray matter loss in the bilateral parietal and posterior cingulate cortices and precuneus region. No difference was noted in diagnostic performance of Z score images between the early- (A(z) = 0.9435) and late-onset (A(z) = 0.9018) groups. CONCLUSION: Differences were noted in the patterns of regional gray matter loss in patients with early-onset AD versus those with late-onset AD. Parietotemporal and posterior cingulate gray matter loss was found in early-onset AD but not in late-onset AD. Z score images obtained with VBM had a great diagnostic performance for mild AD and can be applied for detecting mild AD in clinical examinations.     

A comparison of MRI and echocardiography in hypertrophic cardiomyopathy.

This study compares MRI and echocardiography as imaging modalities in hypertrophic cardiomyopathy, with particular reference to measurement of left ventricular wall thickness and mass. 10 subjects underwent echocardiography and MRI. Contiguous 10 mm short axis 35 degrees flip angle cine gradient recalled echo MR images were acquired from the apex to the base of the left ventricle at 1.5 tesla. Standard M-mode and cross-sectional echocardiographic views of the left ventricle were obtained. Excellent agreement between measurements occurred with MRI and M-mode echocardiographic assessment of the thickness of the anterior interventricular septum (95% limits of agreement -1.5 to +1.5 mm). Other comparisons of MRI vs M-mode echocardiographic measurements had the following limits of agreement: posterior free wall -3.3 to +2.9 mm; end-diastolic dimension -5 to +8 mm, left ventricular mass -291 to +55.5 g. Comparing MRI with cross-sectional echocardiographic measurements, the limits of agreement were: anterior interventricular septum -2.4 to +1.7 mm, posterior interventricular septum -2.4 to +2.9 mm, posterior free wall -3.4 to +2.5 mm, anterior free wall -2.4 to +1.7 mm, end-diastolic dimension -4.1 to +8 mm. MRI estimates of LVM in systole vs diastole showed good agreement with 95% limits of agreement of -20 to +17 g, with excellent interobserver variability in diastole (-9 to +5 g) and in systole (-7 to +12 g). In conclusion, MRI is superior to echocardiography for the quantification of ventricular mass in the abnormal left ventricle because it does not make invalid geometrical assumptions. Comparisons of wall thickness show greater discrepancy with increasing distance from the echocardiographic transducer. This study suggests that sequential echocardiography could rationalize the need for MRI in left ventricular hypertrophy. A change in anterior septal thickness of > or = 3 mm on echocardiography merits a further MRI study.     

动态心电图诊断变异性心绞痛的价值

目的探讨24 h动态心电图对变异性心绞痛诱发缺血性J波的临床意义。方法回顾性分析15例在动态心电图检测中发生变异性心绞痛诱发缺血性J波,对缺血性J波进行分析。结果缺血性J波发生的导联与冠状动脉病变血管基本相符;变异性心绞痛发作时伴有心律失常,以室性心律失常多见。15例均捕捉到与临床症状相关的一过性J波与ST段抬高伴对应导联ST段压低改变。结论变异性心绞痛合并缺血性J波是心肌严重缺血时伴发的一种超急性期心电图改变,可诱发恶性室性心律失常等, 应高度重视。24 h动态心电图可记录变异性心绞痛发作过程,对变异性心绞痛合并缺血性J波的诊断可以早期发现高危人群。     

Quantitation in echocardiography

Imaging of the heart is the predominant approach to cardiovascular diagnosis in current practice. Of the wide variety of cardiac imaging techniques available, echocardiography is one of the most widely used. Standard methods of quantitation of M-mode and two-dimensional echocardiograms yield reproducible, accurate measurements of cardiac chamber, wall, and great vessel dimensions. Qualitative analysis of valvular appearance and motion permits the diagnosis of a wide variety of valvular disorders. Doppler echocardiography yields information on blood flow velocity and pattern in the heart and great vessels. Evolving methods of quantitation in echocardiography include computerized image enhancement, computer-assisted border detection, analysis of regional left ventricular contraction, three-dimensional reconstruction, contrast-enhanced echocardiography, ultrasound myocardial tissue characterization, and intraoperative echocardiography. Echocardiography is a dynamic, evolving discipline with the potential of defining cardiac structure, function, blood flow dynamics, myocardial perfusion, and tissue characteristics. Thus, ultrasonography will continue to be of major importance in the diagnosis of cardiac disease.     

Fetal echocardiography

In recent years, fetal echocardiography has greatly improved in that most major structural heart defects are detectable from 18 weeks on. Fetal M-mode mapping has also enabled us to detect and diagnose fetal arrhythmias as well as follow their treatment. More recently, pulsed Doppler and color-flow mapping have facilitated the dynamic study of blood flow in the cardiovascular system. Fetal echocardiography has now become a sophisticated modality, but is a crucial one to master because most fetuses that have congenital heart defects are not necessarily at any high risk. Evaluation of the fetal heart, therefore, is a recommended part of the routine fetal structural survey.     

Enlargement of the right heart in the endurance athlete: a two-dimensional echocardiographic study

M-mode echocardiographic studies of endurance-trained athletes have provided conflicting data for right ventricular (RV) dimensions and no data for right atrial (RA) size. Since two-dimensional echocardiography provides a more accurate measurement of the RV and RA, it was employed together with M-mode echocardiography to evaluate 12 male endurance athletes and 12 sedentary controls matched for body size and age. All subjects were screened by history, physical examination, ECG, and maximal exercise testing. RV and RA areas were planimetered in the apical four-chamber view while displaying maximal chamber sizes. Athletes had significantly greater left ventricular (LV) wall thickness (P less than 0.01), LV area (P less than 0.001), and left atrial (LA) area (P less than 0.01). They also had greater RV area (P less than 0.01), RV wall thickness (P less than or equal to 0.05), and RA area (P less than or equal to 0.01). Maintained proportionality of the cardiac chamber dimensions in the athletes was shown by similar ratios of right-to-left ventricular areas, right-to-left atrial areas, and right-to-left ventricular wall thicknesses in both groups. The symmetry of the greater athlete's heart differs from most pathological conditions which have heterogeneous effects on specific cardiac chambers.     

The usefulness of 123I-BMIPP myocardial SPECT in diagnosis for silent myocardial ischemia induced by vasospasm

This study was designed to evaluate the clinical usefulness of 123I-BMIPP myocardial SPECT in patients with silent myocardial ischemia induced by vasospasm. Ultrasonic echocardiography (UCG), Holter electrocardiogram recording (Holter ECG), exercise 201Tl myocardial SPECT (EX-Tl) and rest 123I-BMIPP myocardial SPECT (BMIPP) were performed in 8 patients with asymptomatic vasospasm without history of myocardial infarction. The sensitivity of each modality in detecting coronary artery spasm was 37.5% (3 of 8 cases) for UCG, 37.5% (3 of 8 cases) in Holter ECG, 25.0% (2 of 8 cases) in Ex-Tl, 62.5% (5 of 8 cases) on initial BMIPP images and 75.0% (6 of 8 cases) on delayed BMIPP images. Severity of regional left ventricular wall motion abnormality in UCG correlated with the severity of regionally decreased tracer uptake in BMIPP. The washout rate of BMIPP was 18.7 +/- 2.4 in normal controls, 32.4 +/- 5.9 in asymptomatic vasospasm, and 38.2 +/- 4.0 in asymptomatic vasospasm with abnormal left ventricular wall motion. It was suggested that 123I-BMIPP myocardial SPECT might be useful for assessing asymptomatic vasospasm.     

Spin-echo M-mode NMR imaging.

A nuclear magnetic resonance (NMR) imaging and display method for the observation of the continuous motion of objects is presented. By modifying a line scan technique, the spin-density distribution along a line is displayed in succession. Although spatial information is limited to only one dimension, the motion of the object is recorded at intervals of 55 ms by using a commercially available NMR imaging system. In a phantom study, this method yielded accurate velocity measurements along a single axis. When the method was applied to the human chest, an image analogous to that of M-mode echocardiography was obtained. This method, which can be called spin-echo M-mode NMR imaging, approaches the functional analysis of cardiac wall motion in regions where echocardiography is not possible. The effects of respiratory motion on the left ventricular wall were recorded in addition to its intrinsic contractile motion in an image obtained along a line parallel to the cranio-caudal axis of the body. The advantages of this method to assess cardiac wall motion in a patient with an arrhythmia were also demonstrated.     

双源CT虚拟平扫在头部检查的初步应用

目的 探讨双源CT双能量头部虚拟平扫(VNC)的图像质量和临床应用价值.方法 对62例临床怀疑脑血管病变的患者,使用双源CT进行头部常规平扫(CNC)和双能量CTA检查,利用双能量软件得到VNC图像.比较CNC和VNC图像灰质、白质、脑脊液、高密度出血性和低密度缺血性病变的CT值,使用4分法对图像质量进行主观评价,比较两组图像的噪声、辐射剂量和病变检出率,使用配对t检验、Wilcoxon符号秩检验和χ2检验(McNemar检验和Kappa检验)进行统计分析.结果 CNC与VNC图像灰质、白质、脑脊液、高密度病变及低密度病变的CT值分别为[(43.3±1.5)和(33.2±1.3)HU,t=46.98]、[(32.9±1.3)和(28.8±1.6)HU,t=16.28]、[(9.0±1.4)和(5.3±1.9)HU,t=12.41]、[(62.8±10.0)和(51.3±11.5)HU,Z=-4.37]、[(20.7±4.7)和(18.0±6.9)HU,t=3.84],差异均有统计学意义(P值均＜0.01).VNC图像噪声[(1.63±0.34)HU]大于CNC图像[(0.99±0.18)HU](Z=-6.41,P＜0.01).VNC图像有效剂量[(0.53±0.08)mSv]低于CNC[(1.37±0.23)mSv](Z=-6.45,P＜0.01).CNC和VNC图像噪声、颅底伪影、灰白质对比、高密度和低密度病变显示的主观评分分别为(3.9±0.3)和(2.7±0.5)分、(3.7±0.5)和(2.4±0.9)分、(3.3±0.6)和(1.3±0.5)分、(4.0±0.0)和(3.0±0.4)分、(3.9±0.3)和(3.2±0.8)分,VNC图像噪声与颅底伪影的评分较CNC图像低(Z值分别为-6.84、-6.15,P值均＜0.01),灰白质对比、高密度和低密度病变显示低于CNC图像(Z值分别为-7.01、-4.52和-3.12,P值均＜0.01).在个体水平,VNC图像显示高密度出血性病变29例,无假阳性和假阴性病例,敏感性、特异性、阳性预测值和阴性预测值均为100.0%(29/29、33/33、29/29、33/33),与CNC一致(P＞0.05,Kappa值=1.000);VNC图像显示低密度缺血性病变22例,假阳性1例,假阴性2例,敏感性、特异性、阳性预测值和阴性预测值分别为91.3%(21/23)、97.4%(38/39)、95.5%(21/22)和95.0%(38/40),与CNC图像(23例)差异无统计学意义(χ2=0.00,P＞0.05,Kappa值=0.895).在病灶水平,VNC图像显示出血灶53个,假阴性4个,无假阳性,敏感性、特异性、阳性预测值和阴性预测值分别为93.0%(53/57)、100.0%(38/38)、100.0%(53/53)和90.5%(38/42),VNC图像对出血灶的显示率与CNC差异无统计学意义(χ2=2.25,P＞0.05,Kappa值=0.914);VNC图像显示低密度病灶38个,假阳性2个,假阴性13个,敏感性、特异性、阳性预测值和阴性预测值分别为73.5%(36/49)、96.4%(53/55)、94.7%(36/38)和80.3%(53/66),VNC图像对低密度病灶的显示率低于CNC(χ2=6.67,P＜0.01,Kappa值=0.707).结论 与CNC相比,头部VNC辐射剂量低,但图像质量下降,对出血性病变具有替代CNC的潜在使用价值,对缺血性病变也有一定的参考价值.

Abstract：

Objective To investigate image quality and clinical value of dual-source dual energy virtual non-contrast (VNC) CT of the head. Methods Sixty-two patients suspected of cerebrovascular diseases underwent conventional non-contrast (CNC) CT and dual energy CTA examination of the head with dual-source CT. Virtual non-contrast images were reconstructed using dual energy software. The CT values of gray matter, white matter, cerebrospinal fluid, hyperdense hemorrhagic lesion and hypodense ischemic lesion were compared between CNC and VNC images. A four-score scale was used to assess image quality subjectively. Image noise, radiation dosage and detection rate were compared between CNC and VNC images. Paired t test, Wilcoxon signed ranks test and Chi-square test (McNemar test and Kappa test) were used. Results The CT value on CNC and VNC images, were (43. 3 ± 1.5) and (33. 2 ± 1.3) HU for gray matter (t = 46.98, P ＜ 0. 01), (32. 9 ± 1.3) and (28.8 ± 1.6) HU for white matter(t = 16. 28, P ＜0.01), (9.0 ± 1.4) and (5.3 ± 1.9) HU for cerebrospinal fluid (t=12.41, P＜0.01),(62.8 ±10.0) and (51.3 ± 11.5) HU for hyperdense lesion (Z = -4.37, P ＜ 0.01), (20.7 ±4.7) and (18.0 ±6. 9) HU for hypodense lesion (t = 3. 84, P ＜ 0. 01), respectively. VNC images[(1.63 ±0.34) HU]had more noise than CNC images[(0.99±0.18) HU](Z= -6.41, P＜0.01). VNC [(0. 53 ± 0. 08) mSv]had less effective dose than CNC[(1.37 ± 0. 23) mSy](Z= - 6. 45, P ＜ 0. 01).In subjective assessment, VNC images had more noise (2. 7 ± 0. 5 for VNC and 3.9 ± 0. 3 for CNC,Z = -6. 84, P ＜ 0. 01) and skull base-related artifacts (2. 4 ± 0. 9 for VNC and 3.7 ± 0. 5 for CNC,Z = -6. 15, P ＜0. 01) than CNC images. The gray/white matter contrast (1.3 ± 0. 5 for VNC and 3.3 ±0. 6 for CNC, Z = - 7. 01, P ＜ 0. 01), hyperdense lesion display (3.0 ± 0. 4 for VNC and 4. 0 ± 0. 0 for CNC,Z = -4. 52, P ＜ 0. 01) and hypodense lesion display (3.2 ± 0. 8 for VNC and 3.9 ± 0. 3 for CNC,Z= -3. 12, P ＜0. 01) on VNC images were lower than those on CNC images. In per-patient analysis,29 cases of hyperdense lesion (hemorrhage) were found on VNC images without misdiagnosis. The sensitivity, specificity, positive predictive value and negative predictive value were all 100. 0% (29/29,33/33, 29/29, 33/33). VNC images had the same detection rate of hyperdense lesions as CNC images (P ＞0. 05, Kappa = 1. 000) at per-patient level. Twenty-two patients with hypodense ischemic lesions were found on VNC images with one false positive case and two false negative cases. The sensitivity,specificity, positive predictive value and negative predictive value were 91.3% (21/23), 97.4%(38/39), 95.5% (21/22) and 95.0% (38/40) respectively. No statistical difference was found in detecting hypodense lesions between VNC and CNC images (χ2 = 0. 00, P ＞ 0. 05, Kappa = 0. 895). In per-lesion analysis, 53 hemorrhage lesions were found on VNC images with false negative results of four lesions and no false positive result. The sensitivity, specificity, positive predictive value and negative predictive value were 93.0% (53/57), 100. 0% (38/38), 100. 0% (53/53) and 90. 5% (38/42)respectively. There was no significant difference in detection rate of hyperdense lesion between VNC and CNC images (χ2 =2. 25, P ＞0. 05, Kappa =0. 914). Thirty-eight hypodense lesions were found on VNC images with 2 false positive lesions and 13 false negative lesions. The sensitivity, specificity, positive predictive value and negative predictive value were 73.5% (36/49), 96.4% (53/55), 94. 7% (36/38)and 80. 3% (53/66) respectively. The detection rate of hypodense lesion on VNC images was lower than that on CNC images (χ2 = 6. 67 ,P ＜ 0.01, Kappa = 0. 707). Conclusion Compared with CNC images,head VNC images have reduced image quality and radiation dosage. VNC images can replace CNC images potentially in detecting intracranial hemorrhage and provide information for ischemic cerebrovascular diseases to some extent.     

Assessment of global and regional left ventricular function and volumes with 64-slice MSCT: A comparison with 2D echocardiography

Background  In patients with coronary artery disease (CAD), LV function and volumes are important parameters for long-term prognosis. Multislice computed tomography (MSCT) allows noninvasive assessment of the coronary arteries, but the accuracy of 64-slice MSCT for the assessment of left ventricular (LV) volumes and function is unknown. Methods and Results  A head-to-head comparison between 64-slice MSCT and 2-dimensional (2D) echocardiography was performed in 40 patients with known or suspected CAD. The LV end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV) were determined and the LV ejection fraction (LVEF) was derived. Regional wall motion was assessed visually using a 17-segment model. A 3-point scoring system was used to assign to each segment a wall motion score: 1 = normokinesia, 2 = hypokinesia, 3 = akinesia or dyskinesia. Two-dimensional echocardiography served as the gold standard. MSCT agreed well with 2D echocardiography for assessment of LVEDV (r = 0.97; p < .0001) and LVESV (r = 0.98; p < .0001). An excellent correlation between MSCT and 2D echocardiography was shown for the evaluation of LVEF (r = 0.91; p < .0001). Agreement for the assessment of regional wall motion was excellent (96%, κ = 0.82). Conclusions  An accurate assessment of global and regional LV function and volumes is feasible with 64-slice MSCT. This work was supported by The Netherlands Heart Foundation, The Hague, The Netherlands, grant numbers 2002B105 (J.D.S.) and 2001D032 (J.W.J.).     

Left ventricular mass index measured by quantitative gated myocardial SPECT with<Superscript>99m</Superscript>Tc-tetrofosmin: a comparison with echocardiography

OBJECTIVE: Left ventricular mass is an important determinant of diagnosis and prognosis in patients with heart disease. The aim of the present study was to validate measurement of the left ventricular mass index (LVMI) by quantitative gated myocardial SPECT (QGS) with 99mTc-tetrofosmin by comparing it with echocardiography. METHODS: QGS and M-mode echocardiography (Echo) were performed within one month of each other in 179 patients. M-mode echocardiography was carried out according to Devereux's method. QGS images were acquired one hour after injection of 99Tc-tetrofosmin at rest. Myocardial volume was defined as the volume between the endocardial and epicardial surface in the end-diastolic phase. LVMI (g/m2) was defined as myocardial volume divided by myocardial specific density and corrected for body surface area. QGS LVMI measurements were performed twice by the same observer and independently by two different observers. Regional hypoperfusion in the group of patients with old myocardial infarction (n = 26) was evaluated semiquantitatively on the basis of the total defect score on the resting 99mTc-tetrofosmin SPECT images. RESULTS: Among the patients as a whole QGS LVMI was significantly correlated with Echo LVMI (r = 0.96, p < 0.001). Intra-observer and inter-observer analyses showed significant reproducibility (r = 0.99 and r = 0.98, respectively, p < 0.001). In the patients with old myocardial infarction, but QGS LVMI was significantly lower than Echo LVMI (p < 0.001), and the magnitude of the underestimation was closely related to the severity of the perfusion defect on the resting SPECT images. CONCLUSIONS: Measurements of LVMI by 99mTc-tetrofosmin QGS are reproducible and consistent with echocardiograpic estimates. Underestimation in patients with severe perfusion defects must be taken into consideration.     

基于磁共振图像特征的脑胶质瘤MIB-1指数无创检测

目的探讨脑胶质瘤磁共振图像特征与MIB-1指数的关系。方法利用基本灰度信息、灰度共生矩阵、灰度-梯度共生矩阵、游程长度矩阵和闵可夫斯基泛函来构建磁共振图像肿瘤区域的原始特征集,进而分别利用基于顺序后退与k-最邻近的方法(SBS-KNN)和基于离散粒子群与支持向量机的方法(DPSO-SVM)对原始特征集进行优化,最后利用优化后的特征集进行分类。结果采用DPSO-SVM方法优化的特征集能有效地预测MIB-1指数的范围,在T1加权序列上准确率达到80.88%。结论磁共振图像特征与MIB-1指数密切相关。本文所提出的算法可以较好地预测出MIB-1指数的范围。     

Magnetization transfer effects in multislice RARE sequences.

Magnetization transfer effects are demonstrated to be significant in determining the signal intensity from brain tissues on images acquired with multislice rapid acquisition relaxation enhanced (RARE) sequences. We report studies designed to determine how the signal intensities vary with slice number or, equivalently, off-resonance power deposition. The results obtained in fat, gray matter, and white matter are similar in form to those reported in kidney tissues during classic magnetization transfer experiments (J. Eng, T. L. Ceckler, and R. S. Balaban, Magn. Reson. Med. 17, 304 (1991)). Of clinical significance to RARE practitioners is the increase of contrast-to-noise ratios between gray and white matter on proton density-weighted images with increasing slice number.     

Multi-detector computed tomography and 3-dimensional imaging in a multi-vendor picture archiving and communications systems (PACS) environment

RATIONALE AND OBJECTIVES: To show the impact of the introduction of multi-detector computed tomography (CT) on radiologic workflow and to demonstrate how this reflects on picture archiving and communications systems (PACS) requirements. MATERIALS AND METHODS: Production measurements were obtained from different CT scanners (first two single-slice CT scanners; from December 2001 single and 4-slice CT; from April 2002 single and 16-slice CT) in number of patients from the radiologic information system. Implications on our PACS were recorded in terms of images and studies stored. Furthermore, our PACS design was made so that optimal use of 3-dimensional imaging within the radiologic workflow was possible. Finally, the number of non-diagnosed studies were recorded every day since the start of the transition to a filmless radiology department. RESULTS: This PACS design achieved a high level of integration between simple viewing and advanced 3-dimensional imaging and is optimized for handling large amounts of data. Overall increase of patients scanned with CT from January 2002-December 2003 was 54%. The number of series increased by 286% from December 2001-April 2003 and by 130% from April 2002-December 2003. From January 2002-February 2003, the number of images per patient increased from 175 to 450 (157%). Non-diagnosed studies decreased from about 100-120 before to practically zero after PACS implementation. CONCLUSION: PACS significantly increases productivity because of availability of the images and elimination of certain manual tasks. These results show that although the amount of examinations increases significantly with the introduction of MDCT, simultaneous introduction of PACS and filmless operation allows radiologists to handle the growth in workload.     

Silent pericardial effusion in late pregnancy: A new entity

Of 123 healthy pregnant women examined systematically by M-mode and two-dimensional echocardiography at various stages of gestation, 46 were in their late pregnancy (32nd–38th week) of whom 19 (41.3%) showed unexpected signs of pericardial effusion on the echocardiogram. Following Horowitz’s criteria, the effusion was large in 2, moderate in 4, and small in 13 cases; in all women the condition was clinically silent. Clinical examination was normal in all but 3 women, in whom high blood pressure returned to normal after delivery. The ECG was usually normal (16 of 19 cases) or showed nonspecific ST-T changes. The entity appeared in late pregnancy (not before the 32nd week), was transient, and no longer could be seen within a month after delivery of a normal child. Cause of the effusion was attributed to excessive water and salt retention in those women with an abnormal echocardiogram who at this late stage of gestation had a mean weight gain significantly higher (P<0.03) than in others (13.60±4.28 vs 10.96±3.7 kg) — an observation not reported before in normal pregnancy. Since pericardial effusion cannot be detected by clinical examination or ECG, echocardiography affords a safe and reliable diagnostic approach.     

Two-phase reconstruction for the assessment of left ventricular volume and function using retrospective ECG-gated MDCT: comparison with echocardiography

OBJECTIVE: The aims of our study were to investigate the clinical feasibility of a two-phase reconstruction method based on ECG to evaluate left ventricular (LV) volume and function using cardiac MDCT and to compare these results with those from echocardiography. SUBJECTS AND METHODS: The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction were measured using two different methods of cardiac MDCT in 19 patients who had undergone cardiac MDCT and echocardiography. The first was a two-phase reconstruction method based on retrospective ECG-triggering: The end-systolic phase was reconstructed when the reconstruction window was located halfway in the ascending T wave on ECG, and the end-diastolic phase was reconstructed when the reconstruction window was located at the starting point of the QRS complex on ECG. The second was a multiphase reconstruction method: 20 series of images were reconstructed at every 5% throughout the cardiac cycle. The LV volumes and function determined by the two reconstruction methods were compared. The results measured by cardiac MDCT were compared with those obtained by echocardiography. RESULTS: The LV end-diastolic and end-systolic volumes, stroke volume, and ejection fraction measured by the two-phase reconstruction method correlated well with those measured by the multiphase reconstruction method (r = 0.984, 0.978, 0.969, 0.969, respectively). There were no significant differences between the results of the two different reconstruction methods (p > 0.05). The LV volumes showed moderate to good correlation between cardiac MDCT and echocardiography (0.766 < r < 0.940). Ejection fraction measured by cardiac MDCT yielded a significant overestimation of 2.9% +/- 8.7% (mean +/- SD) compared with that measured by echocardiography. CONCLUSION: A two-phase reconstruction method on cardiac MDCT is relatively simple and can provide an objective standard for reconstructing the appropriate image sets for end-diastole and end-systole without the need to review serial preview images.     

Optimal scan time of oxygen-15-labeled water injection method for measurement of cerebral blood flow

We investigated the optimal scan time for obtaining the maximal signal-to-noise (S/N) ratio in cerebral blood flow (CBF) measured by PET imaging following 15O-water bolus injection. We performed sequential measurements with dynamic scans of six subjects injected at rest while listening to white noise. Each dynamic data set was edited into images corresponding to different scan times and were calibrated to CBF images by the table look-up method. For each scan time, we evaluated a pixel-by-pixel standard deviation of the CBF for sequential measurements. The S/N-ratio of CBF in the gray matter was 10.2 +/- 1.7 and 13.6 +/- 2.9 at a 40 and 120 sec scan time, respectively. The gain of the 120-sec over 40-sec scan time corresponds to an 80% increase in the number of trials to reach the same S/N-ratio in a stimulation-activation study. The simulation study supported the results, in which the maximal S/N-ratio of the CBF was demonstrated to be 90 and 120 sec at a CBF of 80 and 60 ml/100 ml/min, respectively. It is concluded that the optimal scan time of the 15O-water bolus injection method is in the interval from 90 to 120 sec.     

N-isopropyl-p-[123I]iodoamphetamine early dynamic image with ring-type emission CT in cerebrovascular disease

N-isopropyl-p-[123I]iodoamphetamine (IMP) SPECT was done in 14 patients with cerebrovascular disease. Immediately after injection of 3 mCi IMP, sequential 2 minutes SPECT images (dynamic images) were obtained for 15 minutes using a circular detector array emission tomographic system (Shimadzu SET-030W). Then standard SPECT images were obtained at 30 minutes (early images) and 5 hours (delayed images) using a rotating scintillation camera ECT system (GCA-601E, Toshiba). Two patients out of 14 studies showed discrepancy of the findings between dynamic images and early images; dynamic images revealed low uptake area though early images showed no defect. Possible mechanism of this phenomenon might be due to so called redistribution phenomenon occurred during obtaining early images. In conclusion, early dynamic images is useful in cases with slightly decreased cerebral blood flow.