Perceived Dark Rim Artifact in First-Pass Myocardial Perfusion Magnetic Resonance Imaging Due to Visual Illusion.
- 作者列表："Shin T","Nayak KS
OBJECTIVE:To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. MATERIALS AND METHODS:Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. RESULTS:k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. CONCLUSION:Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.
目的: 在对比增强的心肌灌注磁共振图像中，人类视觉错觉有助于心内膜下暗缘伪影。 材料和方法: 生成数值模型以模拟心脏中造影剂的第一次通过，并以常规灰度以及具有降低的亮度变化的色标渲染。从两个健康志愿者获得心脏灌注图像，并通过在数值研究中使用的相同灰度和色标显示。在k空间开窗之前和之后，通过垂直于边界的强度分布视觉和定量地分析左心室 (LV)-心肌边界。 结果: k空间开窗在体模图像中LV-心肌边界附近产生单调递减的信号强度，如在-1.07至-0.14范围内的板附近的负有限差值所证实。然而，暗带仍然出现，这是视觉错觉感知。在去除定量信号下降的k空间开窗后，在体内图像中感知到暗缘，表明感知到的暗缘是视觉错觉。由于LV和心肌之间的较大强度差异，在LV峰值增强时感知的暗缘比心肌峰值增强更强。在数字幻像和体内图像中，由于亮度变化减小，在彩色图中不可见虚幻的暗带。 结论: 视错觉是对比增强心肌灌注MRI中暗缘伪影的另一个潜在原因，如在缺乏定量强度欠摄时感知的虚幻缘所证明的。
METHODS::We present the case of a 61-year-old woman with a large tumoral infiltration extending from the pelvis throughout the inferior vena cava inferior to the right atrium, protruding into the right ventricle and right ventricular outflow tract. She had been treated 10 years before for low-grade endometrial stromal sarcoma by hysterectomy and adnexectomy followed by hormone- and radio-therapy. Due to cancer recurrence, she underwent peritonectomy, appendectomy, and resection of terminal ileum.
METHODS:AIMS:Significant platelet activation after long stented coronary segments has been associated with periprocedural microvascular impairment and myonecrosis. In long lesions treated either with an everolimus-eluting bioresorbable vascular scaffold (BVS) or an everolimus-eluting stent (EES), we aimed to investigate (a) procedure-related microvascular impairment, and (b) the relationship of platelet activation with microvascular function and related myonecrosis. METHODS AND RESULTS:Patients (n=66) undergoing elective percutaneous coronary intervention (PCI) in long lesions were randomised 1:1 to either BVS or EES. The primary endpoint was the difference between groups in changes of pressure-derived corrected index of microvascular resistance (cIMR) after PCI. Periprocedural myonecrosis was assessed by high-sensitivity cardiac troponin T (hs-cTnT), platelet reactivity by high-sensitivity adenosine diphosphate (hs-ADP)-induced platelet reactivity with the Multiplate Analyzer. Post-dilatation was more frequent in the BVS group, with consequent longer procedure time. A significant difference was observed between the two groups in the primary endpoint of ΔcIMR (p=0.04). hs-ADP was not different between the groups at different time points. hs-cTnT significantly increased after PCI, without difference between the groups. CONCLUSIONS:In long lesions, BVS implantation is associated with significant acute reduction in IMR as compared with EES, with no significant interaction with platelet reactivity or periprocedural myonecrosis.
METHODS:BACKGROUND:Aortopulmonary window is an uncommon congenital heart disease, with untreated cases not surviving beyond childhood. However, very rarely it can present in adult patients with features of pulmonary hypertension. Clinically these patients cannot be differentiated from other more common conditions with left to right shunt. Transthoracic echocardiography if performed meticulously, can depict the defect in aortopulmonary septum. RESULTS:We report a case of large unrepaired aortopulmonary window in a 23 years old patient, diagnosed on transthoracic echocardiography.