德国图宾根大学放射线学系潜伏期成像和成像技术实验室主任伯尔尼.J.皮 奇利尔副教授说，“在美国核医学协会年会上，我们展示了{sg}同时利用正电子放射断层扫描和磁共振技术拍摄的人脑图像。正电子放射断层扫描和磁共振使用相同 的测量法是成像技术领域的一次巨大飞跃。正电子放射断层扫描和磁共振技术具有成为神经研究、特定癌症、心脏病和逐步形成的干细胞xx成像方式选择之一的潜 力。我们期望正电子放射断层扫描和磁共振技术能开启了解各种神经紊乱，比如阿尔茨海默病、帕金森病、xx症、抑郁症和精神分裂证等疾病病理学和发病过程的 大门。”
皮 奇利尔指出来自田纳西州大学、德国图宾根大学和西门子医疗解决方案公司的研究人员可能会共同合作进行这一激动人心的研究。他说，“同时使用正电子放射断层 扫描和磁共振成像技术的可行性使我们看到了新兴分子成像技术的发展前景。我们研究所取得的数据证明正电子放射断层扫描和磁共振扫描甚至可以实现正电子放射 断层扫描、功能性磁共振和光谱学多功能成像。正电子放射断层扫描和磁共振技术是一种能对异常软组织进行对比，结合磁共振的高特异性与正电子放射断层扫描在 评估生理和新陈代谢状态方面{zy1}灵敏性的成像技术。”
综合或者混合技术，比如正电子放射断层扫描和电子计算机体层成像及单光子发射计算机断层成像和电子计算机体层成像技术，是将两种成像方法合成在一个机器上，从而能够进行连续进行2次扫描(一种扫描后接着进行另外一种扫描)。皮奇利尔说，“正电子放射断层扫描和磁共振机器由西门子公司开发，于2006年 开始销售，可同时进行磁共振和正电子放射断层扫描，由于有相同的成像容量，因此可拍摄出更佳的图像。正电子放射断层扫描和磁共振系统可同时对人体组织和细 胞的剖析、功能和生物化学情况进行检测，从而使研究人员可以以一种方式将磁共振和正电子放射断层扫描数据联系起来，这在以前是不可的。磁共振和正电子放射 断层扫描成像在获取同步数据方面不会被削弱。正电子放射断层扫描和磁共振技术拍摄的大脑数据显示其成像质量可比表现{zy1}的成像系统，没有任何大的失真问 题。”
皮 奇利尔对正电子放射断层扫描和磁共振系统的一些未来可能应用前景进行了阐述。正电子放射断层扫描目前虽能够区分出早期阿尔茨海默病所引发的轻微感知损伤， 但是却无法确定因萎缩症引发的大脑减损量。他说，“通过结合磁共振和正电子放射断层扫描技术，临床医生们可以能够更加合理地确定感知损伤和萎缩症。此外， 将磁共振和正电子放射断层扫描合成技术与新兴神经生物标志技术结合在一起拥有改善状况评估的巨大应用前景。同时对于心脏病人而言，该技术可帮助医生研究如 何在心脏病后抢救可挽救大脑组织。”
正电子放射断层扫描成像技术使用了非常少量的放射线材料以瞄准特定的器官、骨骼或者组织。注入放射性示踪剂(比如氟代脱氧葡萄糖)， 然后使用与计算机相连的特定类型照相机进行探测，为医生提供xx的人体被照射区域图像及人体生物学功能分子图像。核磁共振成像使用无线电波和强磁场拍摄人 体内部器官和组织的清晰和详细图像。功能性核磁共振成像是一种利用磁共振成像检测大脑活跃部分快速和微小的新陈代谢变化的方法。光谱分析技术用于检测人体 生物化学要素。
西门子正电子放射断层扫描和磁共振成像技术是一种非商用专门对大脑进行正电子放射断层扫描的原型机，该原型机中嵌入了商用3T核磁共振扫描仪。原型机是大脑正电子放射断层专用扫描，采用了下一代雪崩光电二极管探测技术。雪崩光电二极管探测技术使正电子放射断层扫描器不受磁场影响，从而能提供{zy1}的正电子放射断层扫描结果。
A First: Simultaneous PET/MR Images Of The Brain Debut, Increase Molecular Imaging Capabilities
— The world's first PET/MR images of the human brain--taken simultaneously by positron emission tomography (PET) imaging and magnetic resonance (MR)--debuted during the 54th Annual Meeting of SNM, the world's largest society for molecular imaging and nuclear medicine professionals, June 2--6 in Washington, D.C.
"Here at SNM's Annual Meeting, we are showing the first simultaneously acquired PET/MR images of the human brain," noted Bernd J. Pichler, associate professor and head of the Laboratory for Preclinical Imaging and Imaging Technology in the Department of Radiology at the University of Tuebingen in Germany. "PET/MR, acquired in one measurement, presents a tremendous leap forward in imaging capabilities. PET/MR--acquired in one measurement--has the potential to become the imaging modality of choice for neurological studies, certain forms of cancer, stroke and the emerging study of stem cell therapy," he added. "We expect that PET/MR will open new doors in understanding the pathologies and progression of various neurological disorders like Alzheimer's, Parkinson's, epilepsy, depression and schizophrenia," he emphasized.
"The feasibility of simultaneous PET/MR imaging in humans opens new potentials in the emerging field of molecular imaging. Our data prove that the PET/MR scanner allows even multifunctional imaging with PET, functional MRI (fMRI) and spectroscopy," said Pichler, indicating this exciting work was made possible by a collaborative effort of researchers from the universities of Tennessee and Tuebingen (in Germany) and Siemens Medical Solutions. "PET/MR is an imaging technique that brings the exceptional soft tissue contrast and high specificity of MR together with PET's excellent sensitivity in assessing physiological and metabolic state," he added.
Combined or hybrid technologies--such as PET/CT and SPECT/CT--incorporate both imaging modalities into one machine but conduct the two scans sequentially (one after the other), explained Pichler. "This PET/MR machine--developed by Siemens and which debuted last year--acquires MR and PET scans at the same time, for the same imaging volume and, therefore, produces a higher degree of registration," he said. "The PET/MR system allows simultaneous measurement of anatomy, functionality and biochemistry of the body's tissues and cells, enabling researchers to correlate MR and PET data in a way not previously possible before," Pichler noted. "Neither the MR nor the PET imaging performance was degraded by synchronous data acquisition. The PET/MR data of the human brain revealed image qualities comparable to stand-alone systems without any significant distortions," he said.
Pichler explained some of the future possibilities with this PET/MR system. PET currently can differentiate mild cognitive impairment from early-stage Alzheimer's, but it cannot determine reduced brain volume caused by atrophy. "By combining MR and PET, clinicians may be able to make a more sound determination of both cognitive impairment and atrophy. Furthermore, combining PET/MR and new emerging neurological biomarkers has great potential to strengthen the assessment of the condition," said Pichler. Similarly, in stroke patients, the technology holds the promise of allowing doctors to study which brain tissues might be salvageable after a stroke.
PET imaging uses very small amounts of radioactive materials that are targeted to specific organs, bones or tissues. Radiotracers (such as FDG) are injected and then detected by a special type of camera that works with computers to provide precise pictures of the area of the body being imaged and molecular images of the body's biological functions. MRI uses radio waves and a strong magnetic field to provide clear and detailed pictures of internal organs and tissues. Functional MRI (fMRI) is a procedure that uses MR imaging to measure the quick, tiny metabolic changes that take place in an active part of the brain. Spectroscopy is a procedure that examines the biochemical constituents of a body part.
Siemens' PET/MR is a non-commercially available prototype dedicated brain PET scanner that is inserted into a commercial 3T MRI scanner. The prototype dedicated brain PET scanner uses a next-generation Avalanche Photodiode Detector technology. APD technology renders the PET scanner impervious to magnetic fields while providing excellent PET results.
Article: Scientific Paper 152: H. Schlemmer, B.J. Pichler and C.D. Claussen, Department of Radiology, University of Tuebingen, Tuebingen, Germany; K. Wienhard, W. Heiss, Max-Planck-Institute for Brain Research, Cologne, Germany; M. Schmand, Siemens Medical Solutions, Knoxville, Tenn.; and C. Nahmias and D. Townsend, Department of Cancer Imaging and Tracer Development, University of Tennessee Medical Center, Knoxville, "Simultaneous MR/PET for Brain Imaging: First Patient Scans," SNM's 54th Annual
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