PET/MRI在胰腺肿瘤中的应用

PET/MRI是一种将PET和MRI融合的新型影像诊断技术,其整合了PET提供的人体生理代谢、分子信息和MRI提供的功能及解剖形态信息。相较于CT,MRI具有更高的软组织对比度,可多参数成像,且无辐射。PET/MRI在胰腺癌病灶检测、术前分期和预后评估方面优于PET/CT。~(68)Ga标记的生长抑素受体显像剂PET/MRI能够提高胰腺神经内分泌肿瘤的检测和诊断能力。新型显像剂的研发和应用能够提高胰腺肿瘤PET/MRI的特异性和精准性。就PET/MRI在胰腺癌的诊断、分期及疗效监测的应用价值及其对胰腺神经内分泌肿瘤的研究进展予以综述。     

PET/MR联合成像的应用

PET／MRI 双模态成像整合了 PET 提供的人体生理代谢、分子信息和 MRI 提供的功能及解剖形态信息,实现了 PET 及 MR 成像设备的优势互补,对神经、心血管、肿瘤等疾病的研究及临床诊断具有重要意义,是将功能性成像和解剖性图像相结合的一种成像,提供更多分子、形态与功能信息,已开始应用于临床诊疗和科研工作中。本文将从 PET／MRI 的发展,在肿瘤、心血管和神经系统成像等方面的临床应用进行综述,并探讨其面临的挑战和前景。     

PET/MRI在肺癌中的潜在临床应用价值

PET/MRI作为新出现的融合影像技术,其临床应用价值尚未得到充分证实。与CT相比,MRI具有软组织对比分辨力高、无辐射、多参数成像、能够提供更多功能信息的优势,PET与MRI的融合对于肺癌的潜在应用价值可能要优于PET/CT。简述不同的PET/MRI系统的设计,并从肺结节的检出、鉴别诊断、TNM分期、预后/早期疗效评价/肿瘤复发4个方面介绍PET/MRI在肺癌中的潜在临床价值。     

基于3.0 T PET/MRI的肺癌扩散加权成像的体素匹配分析：利用反相位编码方法进行回波平面成像的畸变校正

正PET/MRI由于可以同时获取PET和MRI信息而在胸部肿瘤成像中备受关注。扩散加权成像(DWI)的几何畸变限制了基于体素的多模态影像分析。目的在肺肿瘤的基     

^18F-FDG PET/CT和PET/MR在恶性肿瘤中的应用价值相仿:2300余例患者的临床研究总结

^18F-脱氧葡萄糖(FDG) PET/CT已成为恶性肿瘤影像学评估的参考标准.PET/MR的优势在于通过多参数影像进一步提高对恶性肿瘤诊断的准确性和肿瘤特征的识别;也有学者探讨了^18F-FDG PET结合MRI提供的精细解剖信息是否提升了肿瘤分期和再分期的准确性.该文首先介绍了PET/MR的结构、成像参数和机器操作方面的内容,后综述现有文献,分析了PET/MR对于恶性肿瘤的评估是否具有增益价值.现有数据分析结果显示,PET/MR适用于大多数类型的恶性肿瘤,其效能与PET/CT相当.PET/MR的优势应用领域主要体现在对前列腺癌和骨转移肿瘤的诊断,非优势应用领域是肺内病变的评估.因此,当MRI仅用于提供病灶解剖结构时,PET/MR和PET/CT对于恶性肿瘤的诊断价值相当.如果检查费用经济可行、且检查流程规范,PET/MR可以代替PET/CT.MRI多参数成像的潜在价值需要更多的临床研究和探索.     

PET/CT和MRI在多发性骨髓瘤中的应用与进展

多发性骨髓瘤（MM）是一种恶性B细胞肿瘤,其主要累及骨髓,部分也可出现髓外浸润。影像学检查是全面评估MM不可或缺的手段,X射线与CT对病灶的检出率低、定量能力差。PET/CT与MRI对MM的评估具有较大的价值,特别是18F-FDG及其他新型分子探针,全身扩散加权成像、动态增强MRI及水脂分离等MRI新技术。笔者就PET/CT及MRI在MM中的应用与进展进行综述。     

孤立性肺结节的影像学诊断和处理

胸部CT,尤其HRCT作为检测和诊断肺结节的首选方法,主要通过形态学评价肺结节,但其也具有一定的局限性。近年来,随着MDCT广泛应用,利用计算机辅助CT三维体积测量技术能较准确地评价结节倍增时间,并且动态增强CT、CT灌注成像也可提供较优良的功能性成像,为进一步准确诊断肺结节提供了更多手段。动态增强MRI及磁共振扩散加权成像也初步应用于肺结节的检测、定性和分期。PET/CT是反映肺结节代谢水平的功能性成像技术,主要应用于肿瘤分期。从形态学和功能性方面对CT、MRI、PET/CT等技术诊断肺结节的优缺点进行综述。     

68Ga/18F标记PSMA在非前列腺癌肿瘤诊疗中的应用进展

前列腺特异性膜抗原(prostate-specific membrane antigen,PSMA)最早在前列腺癌细胞中发现,是前列腺癌诊疗的重要靶点。⁶⁸Ga/¹⁸F-PSMA正电子发射体层成像(positron emission tomography,PET)/计算机体层成像(computed tomography,CT)或PET/磁共振成像(magnetic resonance imaging,MRI)在前列腺癌的诊疗中发挥着重要作用。随着研究和应用的不断深入和拓展,研究者发现肝癌、肺癌、肾癌等其他实体肿瘤均摄取⁶⁸Ga/¹⁸F-PSMA,因此,⁶⁸Ga/¹⁸F-PSMA PET/CT在这些肿瘤诊疗中的价值也逐渐体现出来。本文就⁶⁸Ga/¹⁸F-PSMA PET/CT或PET/MRI在非前列腺癌肿瘤诊疗中的应用进行述评。     

PET/MRI改善癌症患儿管理

一体化PET/MRI通过一站式成像提供肿瘤解剖学及功能评估, 且与18F-FDG PET/CT相比其辐射暴露量减少80%, 因此对癌症患儿的分期与再分期具有显著临床价值。该文回顾了18F-FDG PET/MRI在小儿肿瘤中的临床应用, 尤其关注PET/MRI在患儿管理中的价值。来自4个不同机构的PET/MRI应用先行者分享了他们对PET/MRI技术在癌症患儿评估中特殊优势的见解。文章作者讨论了全身PET/MRI在评估某些解剖区域(如软组织和骨髓)中的价值以及儿童特殊的PET/MRI影像学特征, 并强调了全身PET/MRI如何通过在不失去诊断准确性的同时减少所需放射学检查次数(因此减少辐射暴露), 改善淋巴瘤、肉瘤和神经纤维瘤病患儿的临床管理。文章论述了PET/MRI如何帮助区分恶性肿瘤与感染性或炎性疾病;另外, 简要探讨了PET/MRI用于接受免疫治疗的患儿疗效评估以及对不同诊疗一体化药物评估的未来研究方向。从儿童应用中所获得的经验也可拓展至成人患者的评估中。     

18F-FDG PET/CT与18F-FDG PET/MRI在卵巢癌临床应用中的进展

卵巢癌是妇科恶性肿瘤中病死率最高的肿瘤。18F-FDG PET/CT在卵巢癌的诊断、分期、疗效及预后的评估上优于常规影像技术,可以指导临床采取有针对性的治疗方案,以获得更好的治疗效果。PET/MRI是最近几年继PET/CT后投入临床应用的另外一种多模态影像技术,因其多序列成像、软组织分辨率较高和辐射剂量较低,对卵巢癌的诊治具有独特的优势。笔者对18F-FDG PET/CT和18F-FDG PET/MRI在卵巢癌中的临床应用进行综述。     

PET/MRI of the thorax,abdomen and retroperitoneum: Benefits of the breathing-synchronized scanning

Hybrid imaging using various radiopharmaceuticals is currently essential not only in detection and therapy response monitoring of tumors, but also in assessment of inflammatory or systemic diseases. Combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) is still relatively new method with great prospects of comprehensive assessment using anatomical and multiple functional information. However, benefits of PET/MRI in thorax, abdomen and retroperitoneum are not completely defined. Breathing movements affect imaging of thoracic, abdominal and retroperitoneal organs and pathological structures using PET and MRI. Fast MRI sequences are performed using breath-hold technique; however, acquisition of longer sequences and PET scanning need to be breathing-synchronized. Review article summarizes concrete PET/MRI protocols and importance of concrete MRI sequences and radiopharmaceuticals in different pathological lesions with focus on benefit of breathing-synchronized techniques.     

Value of retrospective image fusion of F-FDG PET and MRI for preoperative staging of head and neck cancer: Comparison with PET/CT and contrast-enhanced neck MRI

Purpose

To assess the clinical value of retrospective image fusion of neck MRI and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET for locoregional extension and nodal staging of neck cancer.

Materials and methods

Thirty patients with carcinoma of the oral cavity or hypopharynx underwent PET/CT and contrast-enhanced neck MRI for initial staging before surgery including primary tumor resection and neck dissection. Diagnostic performance of PET/CT, MRI, and retrospective image fusion of PET and MRI (fused PET/MRI) for assessment of the extent of the primary tumor (T stage) and metastasis to regional lymph nodes (N stage) was evaluated.

Results

Accuracy for T status was 87% for fused PET/MRI and 90% for MRI, thus proving significantly superior to PET/CT, which had an accuracy of 67% (p = 0.041 and p = 0.023, respectively). Accuracy for N status was 77% for both fused PET/MRI and PET/CT, being superior to MRI, which had an accuracy of 63%, although the difference was not significant (p = 0.13). On a per-level basis, the sensitivity, specificity and accuracy for detection of nodal metastasis were 77%, 96% and 93% for both fused PET/MRI and PET/CT, compared with 49%, 99% and 91% for MRI, respectively. The differences for sensitivity (p = 0.0026) and accuracy (p = 0.041) were significant.

Conclusion

Fused PET/MRI combining the individual advantages of MRI and PET is a valuable technique for assessment of staging neck cancer.     

18F-FDG PET/MRI在胰腺癌中的临床应用及新进展

胰腺癌是一种恶性程度高、易转移、进展快、预后差的恶性肿瘤,早期诊断、准确分期和及时的疗效评估对胰腺癌患者至关重要。一体化的PET/MRI作为一种新型的多模态成像技术,集合了MRI对软组织分辨率高、多序列、多参数和PET代谢显像的高灵敏度等优势,在胰腺癌患者的肿瘤分期、疗效评估、预后预测、复发监测等方面具有潜在的应用价值。因此,笔者就18F-氟脱氧葡萄糖（FDG）PET/MRI的优势及其在胰腺癌中的临床应用及新进展进行综述。     

Intracranial meningiomas

Summary Fifty patients with intracranial meningiomas underwent plain and contrast-enhanced examinations with CT and MRI. Each of the MR studies consisted of three plain (T1, proton density and T2-weighted) and a post-contrast series (0.1 mmol Gd-DTPA/kg body weight). All techniques (plain CT, plain MRI, contrastenhanced CT, contrast-enhanced MRI) proved to be highly efficient as regards tumour detection: depending on the technique, an intracranial lesion was demonstrated in 47–50 cases. The image contrast was assessed as good or excellent in 21 cases having plain CT and in 33 cases having plain MRI, but in 46 and 50 of the contrast-enhanced CT and MRI studies respectively. Adequate tumour delineation was achieved in 18 cases with plain CT, in 35 cases with plain MRI and in 46 and 50 cases of the contrast-enhanced CT and MRI examinations. The contrast-enhanced studies proved to be superior to the plain CT and MRI studies as regards image contrast and tumor delineation. Because of the methodological advantages of the MRI technique, contrast-enhanced MRI was judged to be slightly superior to contrast-enhanced CT.     

Combined use of MRI and PET to monitor response and assess residual disease for locally advanced breast cancer treated with neoadjuvant chemotherapy

RATIONALE AND OBJECTIVES: The purpose of the study was to evaluate the hypothesis that magnetic resonance imaging (MRI) and positron emission tomography (PET) are complementary and valuable in monitoring response and assessing residual disease of locally advanced breast cancer (LABC) treated with neoadjuvant chemotherapy. We sought to determine if the combination of the two modalities was more accurate than either alone and could provide better guidance in patient management. MATERIALS AND METHODS: Sixteen lesions in 15 women with LABC were evaluated with MRI, PET, and clinical breast examination (CBE) before and after neoadjuvant chemotherapy. The pre- and posttherapy maximal tumor sizes on MRI and CBE and standard uptake values (SUVs) on PET served as the measurements for clinical response classification and residual disease assessment. Pathologic assessment provided the reference for macroscopic and microscopic pathologic tumor response and residual disease. RESULTS: PET correctly predicted lack of pathologic response in five of six cases (83%); CBE predicted correctly in one of six (17%) cases, and MRI predicted correctly in zero of six cases. When PET predicted response, MRI defined the extent of macroscopic pathologic residual disease accurately in 9 of 10 cases (90%). When posttherapy MRI showed complete response (CR) in eight cases, macroscopic pathologic complete response (mCR) was observed in all eight cases (100%). CONCLUSION: Our study suggests that combined use of MRI and PET is complementary and offers advantages over CBE. PET was more accurate in predicting pathologic nonresponse. Complete response by MRI correlated well with macroscopic pathologic complete response.     

PET和PET/MRI在阿尔茨海默病中的应用

阿尔茨海默病(AD)是老年痴呆最常见的原因,AD的早期诊断有利于改善病人预后。PET和PET/MRI技术在AD的早期诊断和病情评估方面有重要的临床应用价值。现就~(18)F-FDG PET、淀粉样蛋白PET、Tau PET以及PET/MRI在AD方面的发展现状、优势和局限性,以及发展趋势的预测进行综述。     

Clinical application of PET/MRI in oncology

Hybrid imaging with integrated positron emission tomography (PET) and magnetic resonance imaging (MRI) combines the advantages of the high‐resolution anatomic data from MRI and functional imaging data from PET, and has the potential to improve the diagnostic evaluation of various types of cancers. The clinical oncologic applications of this newest hybrid imaging technology are evolving and substantial efforts are underway to define the role of PET/MRI in routine clinical use. The current published literature suggests that PET/MRI may play an important role in the evaluation of patients with certain types of malignancies, involving anatomic locations such as the pelvis and the liver. The purpose of this article is to review the current published PET/MRI literature in specific body oncologic applications. In addition, PET/MRI protocols and some of the technical issues of this hybrid imaging will be briefly discussed. J. Magn. Reson. Imaging 2016;44:265–276.     

全身MRI与PET/CT在淋巴瘤骨髓浸润诊断及预后中的作用

淋巴瘤是一种血液系统恶性肿瘤。淋巴瘤骨髓浸润(BMI)使疾病分期上升至IV期, 是疾病进展、预后较差的标志。常规部位的骨髓活检(BMB)具有创伤性, 且检出率低。PET/CT与全身MRI的出现, 丰富了BMI的检测手段。PET/CT与全身MRI对于淋巴瘤, 尤其是侵袭性淋巴瘤BMI均具有较高的检出率, 二者孰高孰低, 尚未定论。对于红骨髓、良性骨髓病变(炎症等)、淋巴瘤BMI病灶以及肿瘤治疗后骨髓的变化与骨髓残留或复发病灶, 全身MRI很难区分, 而PET/CT却可以很好地鉴别这些病灶。但是, PET/CT存在电离辐射; 对于惰性淋巴瘤的BMI, 超出PET/CT分辨率的病灶, 可能出现假阴性; 某些情况会限制PET/CT的使用, 包括18F-FDG生理性摄取量可能发生改变的正常组织、18F-FDG摄取相关性炎症、高血糖或高胰岛素血症导致的18F-FDG分布的改变、肿瘤患者治疗后出现的骨髓活化等。然而, 这些情况可以使用全身MRI。因此, 全身MRI和PET/CT相辅相成, 优势互补, 但二者均不能代替BMB。对于常规BMB阴性, 但影像学提示阳性的患者, 在影像学引导下进行BMB, 可以提高BMI的检出率。另外, 全身MRI阳性的淋巴瘤BMI患者与全身MRI阴性的淋巴瘤BMI患者相比, 前者预后可能较差。     

Competitive advantage of PET/MRI

Multimodality imaging has made great strides in the imaging evaluation of patients with a variety of diseases. Positron emission tomography/computed tomography (PET/CT) is now established as the imaging modality of choice in many clinical conditions, particularly in oncology. While the initial development of combined PET/magnetic resonance imaging (PET/MRI) was in the preclinical arena, hybrid PET/MR scanners are now available for clinical use. PET/MRI combines the unique features of MRI including excellent soft tissue contrast, diffusion-weighted imaging, dynamic contrast-enhanced imaging, fMRI and other specialized sequences as well as MR spectroscopy with the quantitative physiologic information that is provided by PET. Most evidence for the potential clinical utility of PET/MRI is based on studies performed with side-by-side comparison or software-fused MRI and PET images. Data on distinctive utility of hybrid PET/MRI are rapidly emerging. There are potential competitive advantages of PET/MRI over PET/CT. In general, PET/MRI may be preferred over PET/CT where the unique features of MRI provide more robust imaging evaluation in certain clinical settings. The exact role and potential utility of simultaneous data acquisition in specific research and clinical settings will need to be defined. It may be that simultaneous PET/MRI will be best suited for clinical situations that are disease-specific, organ-specific, related to diseases of the children or in those patients undergoing repeated imaging for whom cumulative radiation dose must be kept as low as reasonably achievable. PET/MRI also offers interesting opportunities for use of dual modality probes. Upon clear definition of clinical utility, other important and practical issues related to business operational model, clinical workflow and reimbursement will also be resolved.     

PET, CT, and MRI in the evaluation of neuropsychiatric disorders: current applications

Positron emission tomography (PET) is emerging as a very useful clinical tool and is adding a great deal to our understanding of the pathophysiology of central nervous system (CNS) disorders. Although computed tomography (CT) and magnetic resonance imaging (MRI) have had a dramatic impact on patient management, there is often an important associated function abnormality which is best assessed by PET. In normal aging and in dementia, the CT and MRI brain changes of atrophy and white matter abnormalities are frequently nonspecific. PET has been more diagnostic, showing characteristic regional metabolic abnormalities. Evaluation of brain tumors such as astrocytomas with PET has demonstrated better correlation with histologic grade compared to CT. Unlike CT or MRI, PET can help to distinguish radiation necrosis from recurrent tumor, and can differentiate the extent of metabolically active tumor from surrounding edema. PET is useful in evaluating stroke patients, providing better prognostic information and demonstrating abnormalities sooner than CT. In epilepsy, PET appears to be superior to MRI in localizing seizure foci in patients with partial seizures. In head trauma patients, metabolic patterns are being described which will likely have an effect on patient management. The use of PET in schizophrenia has yielded very interesting results, with common patterns of metabolic abnormalities being demonstrated. CT and MRI in these patients have not been very useful. PET has also shown promise in movement disorders such as Huntington's disease. It is now clear that PET is already clinically useful and can provide valuable information unobtainable by CT and MRI. As new radioligands are developed, PET is certain to assume an even more important role in the future.