正电子发射计算机断层显像计算机断层扫描在系统性血管炎诊断及病情评估中的应用

系统性血管炎临床表现复杂,对于缺乏特征性表现者的诊断和病情严重程度评估,临床医生面临巨大的挑战。现有影像学检查手段对系统性血管炎的早期、活动性病变敏感性较低。正电子发射计算机断层显像与计算机断层扫描技术(positron emission tomographycomputed tomography,PETCT)对系统性血管炎中巨细胞动脉炎风湿性多肌痛、大动脉炎等大血管炎的诊断具有比较高的敏感新和特异性,特别是在疾病的早期和活动期,而对于中小血管受累的系统性血管炎并无太大帮助。通过PETCT可以全面了解系统性血管炎的解剖和功能定位,弥补其他影像学检查的不足。应注意在PETCT上系统性血管炎与其他血管疾病的鉴别。PETCT检查在系统性血管炎疗效评估中的作用尚有待进一步研究。     

Role of Positron Emission Tomography in Assessing Disease Activity in Ulcerative Colitis: Comparison with Biomarkers

Digestive Diseases and Sciences - Disease activity in ulcerative colitis (UC) is best assessed clinically by Mayo score. 18-Fluorodeoxyglucose positron emission tomography-computerized tomography...     

Positron Emission Tomography in the Study of Hepatic Encephalopathy

Positron-emission tomography (PET) is a quantitative technique that produces images of biological or physiological processes. The nature of the image depends on the tracer used: common tracers used to study HE include ¹⁸F-fluordeoxyglucose, a marker of glucose metabolism; ¹⁵O-water, a marker of cerebral blood flow; and ¹³N-ammonia, a marker of ammonia metabolism. Combined blood flow and ammonia metabolism studies can be used to calculate the permeability surface area product for ammonia at the blood brain barrier. To take full advantage of PET, the data should be analyzed using one of the several sophisticated image processing and analysis techniques that are available. Thus, PET is an ideal technique to evaluate ammonia metabolism and, because of a close linkage of blood flow and glucose metabolism with neural activity, to investigate the neural response to drugs and other treatments and to examine neural systems that mediate specific tasks that are impaired in patients with HE.     

Positron Emission Tomography in the Study of Hepatic Encephalopathy

Positron emission tomography (PET) is a powerful and versatile tool for the investigation of hepatic encephalopathy (HE). This nuclear medicine imaging technique produces quantitative images of the distribution of a radiopharmaceutical at one or more times after its administration. Thus, PET images can be used as data in mathematical models of physiologically important processes, including cerebral blood flow, an index of neural activity, or glucose and ammonia metabolism. Using PET, we have demonstrated abnormalities in all of these processes in patients, even though many had only minimal HE. In HE patients we have found increases in the cerebral ammonia metabolic rate, because of hyperammonemia and an increase in the permeability of the blood–brain barrier to ammonia and abnormal patterns of blood flow and glucose metabolism. In a recent collaborative study, alterations in the resting glucose metabolic rate were found to have significant correlations with a variety of neuropsychological tests used to detect mild HE including Trailmaking A and B, symbol-digit, and other tests. Activation techniques have not yet been applied to map sites affected by HE, but recent data using the paced serial auditory addition test and an auditory continuous performance task have proven to be sensitive indicators in minimally impaired patients. The full potential of PET to evaluate neurotransmitter function is as yet unrealized.     

Parametric Imaging of Biologic Activity of Atherosclerosis Using Dynamic Whole-Body Positron Emission Tomography

BackgroundFor molecular imaging of atherosclerotic vessel wall activity, tracer kinetic analysis may yield improved contrast versus blood, more robust quantitative parameters, and more reliable characterization of systems biology.ObjectivesThe authors introduce a novel dynamic whole-body positron emission tomography (PET) protocol that is enabled by rapid continuous camera table motion, followed by reconstruction of parametric data sets using voxel-based Patlak graphical analysis.MethodsTwenty-five subjects were prospectively enrolled and underwent dynamic PET up to 90 minutes after injection of 2-[¹⁸F]fluoro-2-deoxy-D-glucose (FDG). Two sets of images were generated: 1) the established standard of static standardized uptake value (SUV) images; and 2) parametric images of the metabolic rate of FDG (MR_FDG) using the Patlak plot–derived influx rate. Arterial wall signal was measured and compared using the volume-of-interest technique, and its association with hematopoietic and lymphoid organ signal and atherosclerotic risk factors was explored.ResultsParametric MR_FDG images provided excellent arterial wall visualization, with elimination of blood-pool activity, and enhanced focus detectability and reader confidence. Target-to-background ratio (TBR) from MR_FDG images was significantly higher compared with SUV images (2.6 ± 0.8 vs 1.4 ± 0.2; P < 0.0001), confirming improved arterial wall contrast. On MR_FDG images, arterial wall signal showed improved correlation with hematopoietic and lymphoid organ activity (spleen P = 0.0009; lymph nodes P = 0.0055; and bone marrow P = 0.0202) and increased with the number of atherosclerotic risk factors (r = 0.49; P = 0.0138), where signal from SUV images (SUV_max P = 0.9754; TBR_max P = 0.8760) did not.ConclusionsAbsolute quantification of MR_FDG is feasible for arterial wall using dynamic whole-body PET imaging. Parametric images provide superior arterial wall contrast, and they might be better suited to explore the relationship between arterial wall activity, systemic organ networks, and cardiovascular risk. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of arterial wall disease.     

The Role of 18F Fluorodeoxyglucose Positron Emission Tomography Scanning in the Diagnosis and Management of Systemic Vasculitis

Primary systemic vasculitis is a group of heterogeneous disorders, characterized by inflammation of blood vessels causing end organ damage from ischemia, aneurysm formation or dissection. Delay in the early diagnosis owing to non‐specific symptoms, lack of definitive serological tests, limited availability of biopsy and standard imaging tests pose significant challenge in the management of these diseases. 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning is being increasingly used in the management of systemic vasculitis, especially the large vessel vasculitides: giant cell arteritis (GCA) and Takayasu arteritis (TAK). FDG‐PET involves detection of positron rays emitted by FDG, a fluorinated glucose analogue which is avidly taken up by metabolically active inflammatory cells in the walls of involved blood vessels. 18F‐FDG‐PET scan, especially when combined with computed tomography or magnetic resonance imaging (MRI) can give information about active inflammation as well as structural damage associated with vasculitis. In patients with GCA, FDG‐PET has acceptable sensitivity and specificity for the early diagnosis in non‐cranial GCA, cranial GCA with negative biopsy, assessment of immediate response to treatment, predicting prognosis, but has limited value in serial follow‐up and prediction of relapses. In TAK, FDG‐PET can be useful for early diagnosis and probably for serial assessment of disease activity. FDG‐PET has a limited role in medium and small vessel vasculitis.     

Positron Emission Tomography Combined With Computed Tomography as an Integral Component in Evaluation of Primary Cardiac Lymphoma

We present a case of primary cardiac lymphoma (PCL) that was initially manifest through syncopal episodes. In the diagnostic evaluation, positron emission tomography combined with computed tomography (PET‐CT) made a significant contribution—beyond that which would have been possible if only conventional imaging modalities such as magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE) were utilized—and played a major role in follow‐up. Copyright © 2010 Wiley Periodicals, Inc.     

18F-Sodium Fluoride Positron Emission Tomography and Computed Tomography in Acute Aortic Syndrome

BackgroundAcute aortic syndrome is associated with aortic medial degeneration. ¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) detects microscopic tissue calcification as a marker of disease activity.ObjectivesIn a proof-of-concept study, this investigation aimed to establish whether ¹⁸F-NaF PET combined with computed tomography (CT) angiography could identify aortic medial disease activity in patients with acute aortic syndrome.MethodsPatients with aortic dissection or intramural hematomas and control subjects underwent ¹⁸F-NaF PET/CT angiography of the aorta. Aortic ¹⁸F-NaF uptake was measured at the most diseased segment, and the maximum value was corrected for background blood pool activity (maximum tissue-to-background ratio [TBR_max]). Radiotracer uptake was compared with change in aortic size and major adverse aortic events (aortic rupture, aorta-related death, or aortic repair) over 45 ± 13 months.ResultsAortic ¹⁸F-NaF uptake co-localized with histologically defined regions of microcalcification and elastin disruption. Compared with control subjects, patients with acute aortic syndrome had increased ¹⁸F-NaF uptake (TBR_max: 1.36 ± 0.39 [n = 20] vs 2.02 ± 0.42 [n = 47] respectively; P < 0.001) with enhanced uptake at the site of intimal disruption (+27.5%; P < 0.001). ¹⁸F-NaF uptake in the false lumen was associated with aortic growth (+7.1 mm/year; P = 0.011), and uptake in the outer aortic wall was associated with major adverse aortic events (HR: 8.5 [95% CI: 1.4-50.4]; P = 0.019).ConclusionsIn patients with acute aortic syndrome, ¹⁸F-NaF uptake was enhanced at sites of disease activity and was associated with aortic growth and clinical events. ¹⁸F-NaF PET/CT holds promise as a noninvasive marker of disease severity and future risk in patients with acute aortic syndrome. (¹⁸F Sodium Fluoride PET/CT in Acute Aortic Syndrome [FAASt]; NCT03647566)     

Positron Emission Tomography in the Evaluation of Pulmonary Nodules Among Patients Living in a Coccidioidal Endemic Region

Background

Within a coccidioidal endemic region, pulmonary nodules due to coccidioidomycosis are common. Uptake of ¹⁸fluorodeoxyglucose (¹⁸FDG) by positron emission tomography with computed axial tomography (PET/CT) has been used to assess whether pulmonary nodules are malignant but inflammatory lesions can be positive. The purpose of this study was to compare by PET/CT the ¹⁸FDG uptake in pulmonary nodules likely due to coccidioidomycosis to that of nodules shown to be malignant among patients living in a coccidioidal endemic region.

Methods

We retrospectively reviewed patients who underwent a PET/CT at the Southern Arizona Veterans Affairs Health Care System between January 2008 and March 2012 who were subsequently found on biopsy to have pulmonary nodules that were coccidioidal or granulomatous or were due to malignancy.

Results

Among 245 diagnostic biopsies where the subject had a previous PET/CT, 15 (6.1 %) were either coccidioidal (n = 12) or granulomatous without an identified organism (n = 3). The median maximum standard unit of uptake (SUV_max) on PET/CT of coccidioidal or granulomatous lesions was 2.0 compared to 9.8 for malignant lesions (P < 0.001). The maximum diameter of the coccidioidal or granulomatous nodules was 2.1 cm compared to 3.0 cm for the malignant lesions (P = 0.009). On multivariable analysis, an elevated SUV_max was the only distinguishing feature between the malignant and the granulomatous lesions (OR 1.28, 95 % CI 1.05–1.55; P = 0.013).

Conclusions

Coccidioidal pulmonary nodules take up significantly less ¹⁸FDG than those due to malignancies, but there is considerable overlap between granulomatous and malignant lesions at lower SUV_max.     

Assessment of myocardial perfusion and viability by Positron Emission Tomography

An important evolution has taken place recently in the field of cardiovascular Positron Emission Tomography (PET) imaging. Being originally a highly versatile research tool that has contributed significantly to advance our understanding of cardiovascular physiology and pathophysiology, PET has gradually been incorporated into the clinical cardiac imaging portfolio contributing to diagnosis and management of patients investigated for coronary artery disease (CAD). PET myocardial perfusion imaging (MPI) has an average sensitivity and specificity around 90% for the detection of angiographically significant CAD and it is also a very accurate technique for prognostication of patients with suspected or known CAD. In clinical practice, Rubidium-82 (⁸²Rb) is the most widely used radiopharmaceutical for MPI that affords also accurate and reproducible quantification in absolute terms (ml/min/g) comparable to that obtained by cyclotron produced tracers such as Nitrogen-13 ammonia (¹³N-ammonia) and Oxygen-15 labeled water (¹⁵O-water). Quantification increases sensitivity for detection of multivessel CAD and it may also be helpful for detection of early stages of atherosclerosis or microvascular dysfunction. PET imaging combining perfusion with myocardial metabolism using ¹⁸F-Fluorodeoxyglucose (¹⁸F FDG), a glucose analog, is an accurate standard for assessment of myocardial hibernation and risk stratification of patients with left ventricular dysfunction of ischemic etiology. It is helpful for guiding management decisions regarding revascularization or medical treatment and predicting improvement of symptoms, exercise capacity and quality of life post-revascularization. The strengths of PET can be increased further with the introduction of hybrid scanners, which combine PET with computed tomography (PET/CT) or with magnetic resonance imaging (PET/MRI) offering integrated morphological, biological and physiological information and hence, comprehensive evaluation of the consequences of atherosclerosis in the coronary arteries and the myocardium.     

正电子发射断层扫描显像评价存活心肌的应用现状

随着冠状动脉血运重建术的广泛应用,如何选择适应证以及术后疗效的判断日益引起人们的高度重视,因此,存活心肌的检测,区分心肌损害的可逆性(冬眠心肌、顿抑心肌)和不可逆性(瘢痕组织),对冠状动脉的血运重建术具有决策和预后判断价值.目前,正电子发射断层扫描(PET)被认为是一种评价冠心病患者心肌存活独特、无创而敏感的方法.通过回顾近年来PET显像评价存活心肌的各种方法及对照研究,概述PET对估价存活心肌的价值和最新进展,并对其未来进行初步展望.     

正电子显像在心血管疾病中的研究现状和进展

正电子发射体层摄影术是一种无创性的探测生理性放射性核素在机体内分布的断层显像技术。正电子发射体层摄影术显像不仅广泛应用于肿瘤、神经精神系统等疾病的科学研究和临床工作,同时该技术也广泛应用于对各种心脏疾病的科学研究和临床实践中,如冠心病的诊断、冠心病严重程度的判断、存活心肌的检测、微血管疾病的评价和心脏交感神经功能的研究等。