弥散成像和血流灌注成像磁共振检查对早期脑梗死溶栓治疗的意义

功能MR弥散加权成像(DWI)和血流灌注成像(PWI)磁共振技术的应用可诊断早期脑梗死,结合DWI和PWI可以确定缺血半暗带和血流灌注情况;DWI和PWI可以为溶栓治疗提供较直观的影像学诊断资料。     

核素心肌灌注显像血流定量技术在冠状动脉微血管功能障碍中的应用进展

冠状动脉微血管功能障碍(CMD)广泛存在于包括冠心病在内的多种心血管疾病中。核素心肌灌注显像血流定量技术,包括正电子发射断层成像(PET)和单光子发射计算机断层成像(SPECT),可无创测定心肌血流量和冠状动脉血流储备用于CMD的评估。现就PET和SPECT血流定量分析在CMD中的应用进展进行综述。     

下肢缺血的影像学评估及新进展

下肢缺血的诊断和治疗依赖于精确的影像学评估。传统影像学评估主要包括双相超声、动脉内数字减影血管造影、计算机断层扫描血管造影和磁共振血管造影。它们都主要针对肢体缺血病变的血管解剖结构进行评估。近年来一些针对缺血区域血流灌注情况评估的影像学方法逐渐被应用在外周动脉疾病的诊断和指导治疗中,包括激光多普勒血流仪、高光谱成像、吲哚氰绿血管造影等。改善的传统成像技术与新兴的灌注影像学方法为下肢缺血的诊断和治疗提供了新的思路,两者结合具有重要的临床价值。     

灌注成像在烟雾病中的应用

烟雾病是一种少见的慢性进行性脑血管闭塞性疾病,主要累及颈内动脉末段以及大脑前动脉和大脑中动脉起始段.传统血管造影结果与烟雾病的临床表现及转归常存在差异,而灌注成像则可提供重要的血流动力学信息.目前,CT灌注成像和磁共振灌注成像已广泛应用于临床.文章对这两种影像学技术在烟雾病中的应用进行了综述.     

磁共振在溶栓治疗中的应用

磁共振弥散加权成像和血流灌注成像不仅可以超早期诊断脑梗塞,明确缺血部位、缺血范围,估计缺血半暗带的大小和鉴别短暂性脑缺血发作;特殊磁共振序列还可以确诊早期颅内出血。有助于溶栓对象的筛选和预后的判断,为溶栓治疗提供直观的影像学依据。     

功能磁共振成像技术在急性缺血性卒中的临床应用进展

功能磁共振成像技术、弥散加权成像和灌注加权成像能超早期明确急性缺血性卒中的诊断、判断缺血半暗带的大小及动态观察病情进展，为临床溶栓治疗提供了直观的影像学依据。     

脑灌注成像检查及其在缺血性脑血管病诊疗中的应用

<正>缺血性脑血管病的重要发病机制在于血流中断所引起的脑组织缺血。传统的CT和MRI检查仅能显示已经发生梗死的脑组织,而不能显示梗死前脑组织的一段时间长短不等的缺血状态。脑灌注成像检查作为一项正在普及的检查手段,可以及时的捕捉到脑梗死前的这段缺血时期,从而对指导临床诊疗有着深远的影响。1脑灌注成像检查方法简介多种影像学技术可以定量及半定量评估局部脑灌注。其基本原理是:利用影像学方法追踪示踪剂或造影剂浓度变化。临床常用的技术包括:正电子发射断层显像(PET),单     

肝硬化门静脉高压CT和磁共振成像的表现及研究进展

门静脉高压是肝硬化最常见的并发症。无创的影像学在肝硬化肝实质评估、侧枝循环评价及食管胃底静脉曲张破裂出血评价方面具有重要价值。CT和磁共振成像(MRI)均可反映肝脏形态学、肝实质密度和信号以及血流动力学的变化,对疾病诊断和预后评估有重要的补充价值。CT和磁共振(MR)功能成像如灌注加权成像、MR弹性成像、MR弥散加权成像等,可提供量化的信息,对肝纤维化及早期肝硬化的诊断有潜在的临床应用价值。CT血管成像和MR血管成像,特别是非增强MR血管成像,可显示门静脉分支情况,有助于评估食管胃底静脉曲张破裂风险,发现早期预警指标。综合运用CT及MRI技术,深入研究其临床应用潜力,可以更好的发挥影像学在肝硬化门静脉高压诊断、病情评估及预后判断中的作用。     

脑出血后血肿周围半暗带的影像学

脑出血患者的预后和转归与血肿周围组织损伤和恢复密切相关。脑出血后的病理生理学机制十分复杂,血肿周围组织有局部血流改变,但是否存在与脑缺血类似的“半暗带”尚无定论。目前,这方面的研究主要集中在局部脑血流和代谢的影像学检测方面,常用的研究方法包括单光子发射体层摄影、功能磁共振成像、磁共振波谱分析、正电子发射体层摄影和CT灌注成像等。这些影像学技术的应用对于确定是否存在出血周围半暗带提供了有价值的方法,但还需要进一步的研究证实。     

磁共振功能成像定性和定量诊断肝脏占位性病变

磁共振功能成像技术对肝脏病变的检出、定性和疗效评估具有重要的应用价值。扩散加权成像可无创性地提高肝脏病灶的检出率,可在分子水平定量地鉴别病变的良恶性,并可检测肿瘤组织对治疗的效果;磁共振灌注成像能反映组织血流灌注情况,可应用于临床评价肿瘤新生血管的变化,其灌注参数可以作为监测肿瘤生物学特性和估计预后的重要定量指标;应用肝脏特异性对比剂的功能成像对肝脏病变的检出、定性和疗效评估同样显示出潜在的优势。由此可见,磁共振功能成像技术在肝脏占位性病变的早期诊断、鉴别诊断及疗效评估方面具有较大的优势和临床应用前景。     

Crossed Cerebellar Diaschisis: Three Case Reports Imaging Using a Tri-Modality PET/CT–MR System

Crossed cerebellar diaschisis (CCD) describes a depression of oxidative metabolism glucose and blood flow in the cerebellum secondary to a supratentorial lesion in the contralateral cerebral hemisphere. PET/MR has the potential to become a powerful tool for demonstrating and imaging intracranial lesions .We herein report 3 cases of CCD imaging using a tri-modality PET/CT–MR set-up for investigating the value of adding MRI rather than CT to PET in clinical routine.We describe 3 patients with CCD and neurological symptoms in conjunction with abnormal cerebral fluorodeoxyglucose (FDG) positron emission tomography/computed tomography-magnetic resonance imaging (PET/CT–MR) manifestations including arterial spin-labeling (ASL) and T2-weighted images. In all, ¹⁸FDG-PET/CT detected positive FDG uptake in supratentorial lesions, and hypometabolism with atrophy in the contralateral cerebellum. More than that, hybrid PET/MRI provided a more accurate anatomic localization and ASL indicated disruption of the cortico-ponto-cerebellar pathway.Using pathology or long-term clinical follow-up to confirm the PET and ASL findings, the supratentorial lesions of the 3 patients were respectively diagnosed with cerebral infarction, recurrent glioma, and metastasis.The reports emphasize the significance of multimodality radiological examinations. Multimodality imaging contributes to proper diagnosis, management, and follow-up of supratentorial lesions with CCD.     

Quantifying synovial inflammation:Emerging imaging techniques

Imaging techniques to assess synovial inflammation includes radiography, ultrasound, computed tomography, magnetic resonance imaging(MRI) and recently positron emission tomography. The ideal objective of imaging approaches are to quantify synovial inflammation by capturing features such as synovial hyperplasia, neo-angiogenesis and infiltration of immune cells in the synovium. This may enable clinicians to estimate response to therapy by measuring the improvement in the inflammatory signals at the level of synovium. Ultrasound can provide information regarding thickening of the synovial membrane and can reveal increased synovial blood flow using power Doppler technique. Bone marrow edema and synovial membrane thickness on MRI scan may serve as indicators for arthritis progression. Enhancement of the synovium on dynamic contrast MRI may closely mirror the inflammatory activity in the synovium. Diffusion tensor imaging is an advance MRI approach that evaluates the inflammation related to cell infiltration or aggregation in an inflamed synovium. In this review, we summarize the newer imaging techniques and their developments to evaluate synovial inflammation.     

Is endoscopic ultrasonography still the modality of choice in preoperative staging of gastric cancer?

The treatment option for gastric cancer is usually based on preoperative staging by imaging modalities. Endoscopic ultrasonography (EUS) and computed tomography (CT) have been used as the diagnostic modality of choice in preoperative staging of gastric cancer. Magnetic resonance imaging (MRI) has been employed in several studies, and (¹⁸F) 2-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has emerged as a new promising imaging modality. The purpose of this article is to provide summarized information on preoperative staging using EUS, multi-detector row CT (MDCT), MRI and PET for gastric cancer. In T staging, both EUS and MDCT show high accuracy. MRI seemed to have better performance, but the number of MRI studies is limited. FDG-PET is not able to properly evaluate the depth of invasion. In N staging, the diagnostic accuracy of EUS, MDCT and MRI is not sufficient. In preoperative M staging, MDCT and FDG-PET showed similar diagnostic accuracies. FDG-PET/CT fusion could be expected to show better performance in the future. Physicians should keep in mind that each diagnostic modality has advantages and limitations and choose an appropriate diagnostic strategy tailored for each patient.     

Multimodality imaging in coronary artery disease – “The more the better?”

Multimodality imaging in coronary artery disease (CAD) comprises a combination of information from more than one imaging technique. These combinations, performed in a side-by-side or fusion mode, include computed tomography (CT) and single photon emission computed tomography (SPECT), positron emission tomography (PET) and CT, and PET with magnetic resonance imaging (MRI). Data thus obtained lead to either a summative or synergistic gain of information. For instance, morphology (coronary plaques/stenosis) can be depicted by coronary CT angiography, whereas functional aspects of CAD such as myocardial perfusion abnormalities or myocardial metabolism can be evaluated by the complementary technique in order to separate a hemodynamic significant coronary stenosis from a hemodynamic non-significant stenosis. Distinguishing these two entities has an important impact on patient management. Beyond the diagnostic yield, some of these combinations in multimodality imaging also have prognostic implications. In this article, we will describe different multimodality imaging approaches (CT/SPECT, PET/CT and PET/MRI) for evaluation of CAD in patients with suspected or known CAD and put them into the context of current knowledge.     

Positron emission tomography/computer tomography： Challenge to conventional imaging modalities in evaluating primary and metastatic liver malignancies

Computer tomography (CT) and magnetic resonance imaging (MRI),as conventional imaging modalities,are the preferred methodology for tumor,nodal and systemic metastasis (TNM) staging. However,all the noninvasive techniques in current use are not sufficiently able to identify primary tumors and even unable to define the extent of metastatic spread. In addition,relying exclusively on macromorphological characteristics to make a conclusion runs the risk of misdiagnosis due mainly to the intrinsic limitations of the imaging modalities themselves. Solely based on the macromorphological characteristics of cancer,one cannot give an appropriate assessment of the biological characteristics of tumors. Currently,positron emission tomography/computer tomography (PET/CT) are more and more widely available and their application with 18F-fluorodeoxyglucose (18F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumors,and monitoring the therapeutic efficacy in hepatic malignancies. Recently,investigators have measured glucose utilization in liver tumors using 18F-FDG,PET and PET/CT in order to establish diagnosis of tumors,assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. PET/ CT with 18F-FDG as a radiotracer may further enhance the hepatic malignancy diagnostic algorithm by accurate diagnosis,staging,restaging and evaluating its biological characteristics,which can benefit the patients suffering from hepatic metastases,hepatocellular carcinoma and cholangiocarcinoma.     

Thoracic positron emission tomography: 18F-fluorodeoxyglucose and beyond

Ongoing technologic and therapeutic advancements in medicine are now testing the limits of conventional anatomic imaging techniques. The ability to image physiology, rather than simply anatomy, is critical in the management of multiple disease processes, especially in oncology. Nuclear medicine has assumed a leading role in detecting, diagnosing, staging and assessing treatment response of various pathologic entities, and appears well positioned to do so into the future. When combined with computed tomography (CT) or magnetic resonance imaging (MRI), positron emission tomography (PET) has become the sine quo non technique of evaluating most solid tumors especially in the thorax. PET/CT serves as a key imaging modality in the initial evaluation of pulmonary nodules, often obviating the need for more invasive testing. PET/CT is essential to staging and restaging in bronchogenic carcinoma and offers key physiologic information with regard to treatment response. A more recent development, PET/MRI, shows promise in several specific lung cancer applications as well. Additional recent advancements in the field have allowed PET to expand beyond imaging with ¹⁸F-flurodeoxyglucose (FDG) alone, now with the ability to specifically image certain types of cell surface receptors. In the thorax this predominantly includes ⁶⁸Ga-DOTATATE which targets the somatostatin receptors abundantly expressed in neuroendocrine tumors, including bronchial carcinoid. This receptor targeted imaging technique permits targeting these tumors with therapeutic analogues such as ¹⁷⁷Lu labeled DOTATATE. Overall, the proper utilization of PET in the thorax has the ability to directly impact and improve patient care.     

Role of advanced imaging techniques in the evaluation of oncological therapies in patients with colorectal liver metastases

In patients with colorectal liver metastasis (CRLMs) unsuitable for surgery, oncological treatments, such as chemotherapy and targeted agents, can be performed. Cross-sectional imaging [computed tomography (CT), magnetic resonance imaging (MRI), 18-fluorodexoyglucose positron emission tomography with CT/MRI] evaluates the response of CRLMs to therapy, using post-treatment lesion shrinkage as a qualitative imaging parameter. This point is critical because the risk of toxicity induced by oncological treatments is not always balanced by an effective response to them. Consequently, there is a pressing need to define biomarkers that can predict treatment responses and estimate the likelihood of drug resistance in individual patients. Advanced quantitative imaging (diffusion-weighted imaging, perfusion imaging, molecular imaging) allows the in vivo evaluation of specific biological tissue features described as quantitative parameters. Furthermore, radiomics can represent large amounts of numerical and statistical information buried inside cross-sectional images as quantitative parameters. As a result, parametric analysis (PA) translates the numerical data contained in the voxels of each image into quantitative parameters representative of peculiar neoplastic features such as perfusion, structural heterogeneity, cellularity, oxygenation, and glucose consumption. PA could be a potentially useful imaging marker for predicting CRLMs treatment response. This review describes the role of PA applied to cross-sectional imaging in predicting the response to oncological therapies in patients with CRLMs.     

Surveillance of patients after initial treatment of ovarian cancer

The surveillance of ovarian cancer patients after initial treatment is a challenging question in clinical practice. Serum CA 125 assay, physical examination, and imaging examinations have been employed with different time schedules for the follow-up of asymptomatic patients. Rising serum CA 125 levels may precede the clinical detection of relapse in 56-94% of cases with a median lead time of 3-5 months. An ongoing randomised phase III European trial is comparing the benefits of early administration of chemotherapy based on serum CA 125 assay alone versus delaying treatment until clinical or radiological detection of recurrent disease. Physical examination, with or without ultrasound, is very useful for the surveillance of these patients, since approximately 25-50% of relapses involve the pelvis. Additional radiological imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), are usually performed in asymptomatic patients with rising CA 125 levels as well as in patients with suspicious symptoms or signs. Integrated positron emission tomography (PET) and CT scanners (PET/CT) can identify recurrent disease in tissues that appear normal at CT imaging as well as metastatic lesions intimately associated with the bowel wall that are difficult to detect with CT or MRI, so that in most series PET/CT has a higher diagnostic reliability than that of conventional imaging techniques. Moreover, PET/CT can disclose unusual supra-diaphragmatic spreading of the disease and may be very helpful for treatment planning, especially for the selection of patients suitable for secondary surgical cytoreduction. A prospective, randomised trial of therapeutic interventions based on stratification by PET/CT disease status could elucidate the real impact of this diagnostic procedure in the management of patients with recurrent ovarian cancer.     

Molecular imaging of plaques in coronary arteries with PET and SPECT

Coronary artery disease remains a major cause of mortality. Presence of atherosclerotic plaques in the coronary artery is responsible for lu-men stenosis which is often used as an indicator for determining the severity of coronary artery disease. However, the degree of coronary lumen stenosis is not often related to compromising myocardial blood flow, as most of the cardiac events that are caused by atherosclerotic plaques are the result of vulnerable plaques which are prone to rupture. Thus, identification of vulnerable plaques in coronary arteries has become increas-ingly important to assist identify patients with high cardiovascular risks. Molecular imaging with use of positron emission tomography （PET） and single photon emission computed tomography （SPECT） has fulfilled this goal by providing functional information about plaque activity which enables accurate assessment of plaque stability. This review article provides an overview of diagnostic applications of molecular imaging tech-niques in the detection of plaques in coronary arteries with PET and SPECT. New radiopharmaceuticals used in the molecular imaging of coro-nary plaques and diagnostic applications of integrated PET/CT and PET/MRI in coronary plaques are also discussed.