PET／CT—功能与解剖结构的同机图像融合

PET/CT为近几年出现的一种新技术,将PET与CT安装在同一机架上,一次扫描可获得PET与CT的融合图像,对定位诊断肿瘤、指导肿瘤放疗计划、选择活检部位及监测疗效等具有重要价值,同时,CT提供了一种PET衰减校正的方法,本文简要介绍PET/CT的结构设计与性能、优势及目前尚存在的技术问题。     

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/CT在儿科恶性肿瘤中的应用进展

自PET/CT进入临床以来,主要应用于成人肿瘤的良恶性鉴别、原发灶寻找、临床分期和再分期、疗效评估、指导手术和放化疗计划以及预测生存期等方面,在儿童中的应用相对较少。从国内外相关的文献来看,PET/CT在国内儿科肿瘤诊断中的应用与国外有一定的差距。究其原因,主要与医用放射性核素知识的普及程度低,以及临床对PET/CT在儿科恶性肿瘤中的应用认知度不够相关,以致国内儿科PET/CT工作开展少,缺乏经验,从而形成一种恶性循环。该文主要从以上两方面分别进行阐述,希望促进PET/CT在儿科恶性肿瘤中的应用。     

18F-氟脱氧葡萄糖PET/CT在胰腺癌放疗中的应用

18F-氟脱氧葡萄糖PET/CT在胰腺癌的放疗中具有重要的应用价值。PET/CT较常规影像学检查能提高胰腺癌放疗前的诊断及分期准确性。在放疗过程中,以PET/CT检查为基础的靶区勾画能够准确地覆盖肿瘤组织及保护周围正常组织,同时可以按照其所提示的肿瘤代谢活性调整放疗计划。PET/CT还能够进行放疗的疗效评估及预后评判。相信随着研究的进展,18F-氟脱氧葡萄糖PET/CT将在胰腺癌放疗中发挥越来越重要的作用。     

18F-FDG PET/CT在宫颈癌诊治中的临床价值

宫颈癌是常见的女性恶性肿瘤,其诊治是一项系统的工程。阴道镜活检是诊断金标准,而临床表现、触诊、CT、MRI、超声、PET/CT以及血肿瘤指标等都可辅助宫颈癌的诊断、分期以及预后监测。PET/CT利用氟代脱氧葡萄糖(¹⁸F-FDG)为示踪剂,观察机体对示踪剂的摄取活动来对病灶进行判断,是一项结构与功能显像相结合的新型检查手段。PET/CT对宫颈癌的诊治有较高的价值,已经越来越多的应用到临床中,尤其是对淋巴结及远处器官转移的诊断。     

淋巴瘤18F－FDG PET/CT影像组学的应用及研究进展

18F-FDG PET/CT是诊断淋巴瘤最重要的检查方法之一, 其在淋巴瘤的诊断分期、疗效评估、预后预测及临床决策等方面发挥着重要作用。影像组学是一种利用复杂的生物信息学方法从医学图像中提取定量信息来表征肿瘤异质性的技术。18F-FDG PET/CT影像组学方法已应用于量化肿瘤内异质性, 在淋巴瘤的研究颇具潜力和价值。该文就18F-FDG PET/CT影像组学在淋巴瘤的应用及研究进展进行综述。     

^11G—MET PET在脑肿瘤中的应用

^11G-NET（^11G-蛋氨酸）是目前用于肿瘤PET最多的氨基酸类显像剂之一，它能反映体内氨基酸的转运、肿瘤氨基酸的代谢及蛋白质的合成。^11G-MET PET能用于脑肿瘤的诊断、区分肿瘤复发及放射性坏死，早期评价治疗效果，尤其对肿瘤周边组织及低度恶性肿瘤的诊断要优于^18F-FDG PET、CT和MRI。     

恶性淋巴瘤的多模态显像研究进展

医学影像学技术在肿瘤的临床分期、再分期、疗效评价甚至预后判断中发挥着重要作用,多模态影像技术（如PET/CT和PET/MR）近年来发展的非常迅速。18F-FDG PET/CT已广泛用于亲和18F-FDG的恶性淋巴瘤的初始分期以及疗效评估,治疗期间使用18F-FDG PET/CT评估治疗反应的价值尚不确定,初步的研究认为PET/MR应用于淋巴瘤的分期是可行的。笔者就多模态显像PET/CT、PET/MR在淋巴瘤中的研究现状及进展进行综述。     

肺神经内分泌肿瘤的CT与18F-FDG PET/CT显像特征的分析

目的 探讨肺神经内分泌肿瘤（PNETs）的CT与18F-氟脱氧葡萄糖（FDG）PET/CT显像特征,比较单纯PET/CT与基于PET/CT联合增强CT及高分辨率CT多模态显像的诊断准确率。 方法 回顾性分析2010年1月至2019年5月于西南医科大学附属医院经组织病理学检查确诊的44例PNETs患者的临床资料和CT、PET/CT影像学资料,其中男性34例、女性10例,年龄14~78（57.3±10.0）岁。将PNETs患者分为类癌组（8例）、大细胞神经内分泌癌（LCNEC）组（15例）和小细胞肺癌（SCLC）组（21例）。分析所有患者的CT与PET/CT表现,观察PNETs各亚型的CT与PET/CT显像特征。采用受试者工作特征（ROC）曲线分析计算最大标准化摄取值（SUV_max）的诊断效能及临界值。以组织病理学检查结果为“金标准”,比较单纯PET/CT与基于PET/CT联合增强CT及高分辨率CT多模态显像的诊断准确率。计量资料的多组间比较采用单因素方差分析,两组间比较采用最小显著差异法;计数资料的比较采用χ2检验和Fisher确切概率法。 结果 类癌组患者的发病年龄低于LCNEC组与SCLC组患者[（46.62±8.09）岁对（61.47±8.03）岁对（58.52±9.39）岁],且差异有统计学意义（F=6.186,P=0.004）;在性别、吸烟史等方面与LCNEC组和SCLC组患者的差异均无统计学意义（χ2=1.220、4.539;均P>0.05）。类癌组、LCNEC组、SCLC组患者在肿瘤部位、有无分叶征、阻塞性肺炎或肺不张、纵隔淋巴结转移、肺门淋巴结转移、纵隔及肺门淋巴结同时转移、远处转移、周围血管侵犯等方面的差异均有统计学意义（χ2=6.662~9.877,均P<0.05）;而在肿瘤最大径、肿瘤形态、密度、强化程度、有无钙化、毛刺征、有无坏死和囊变、胸腔积液、支气管侵犯和胸膜增厚等方面的差异均无统计学意义（F=0.370,χ2=0.298~8.472;均P>0.05）。LCNEC组和SCLC组的SUV_max显著高于类癌组（13.79±3.06对9.51±2.49对4.52±1.77）,且差异有统计学意义（F=32.43,P<0.01）;鉴别LCNEC和SCLC的SUV_max临界值为12.25,曲线下面积为0.860（95%CI:0.729~0.991,P<0.01）,灵敏度为80.00%,特异度为81.00%。单纯PET/CT与基于PET/CT联合增强CT及高分辨率CT多模态显像诊断PNETs的准确率分别为65.91%（29/44）和87.80%（36/41）,且差异有统计学意义（χ2=5.655,P=0.017）。 结论 PNETs的CT与PET/CT显像具有一定特征性,PET/CT联合增强CT及高分辨率CT多模态显像可提高PNETs的诊断准确率。     

~(18)F-脱氧葡萄糖PET/CT与增强CT在胰腺癌鉴别诊断中应用价值

目的探讨~(18)F-脱氧葡萄糖(~(18)F-FDG)正电子发射计算机断层显像(PET)、增强CT在胰腺癌鉴别诊断中的应用价值。方法选取自2011年5月至2016年8月沈阳军区总医院收治的经B超、CT、核磁共振成像(MRI)以及临床综合资料证实为胰腺占位性病变的56例患者为研究对象。对所有56例患者行~(18)F-FDG PET/CT全身检查及增强CT检查。比较单纯~(18)F-FDG PET/CT、增强CT显像及两种显像方法联合应用对胰腺良恶性肿瘤诊断的灵敏度、特异度、阳性预测值、阴性预测值及准确率等,以及与最终诊断的一致性。结果本组56例胰腺病变患者中,胰腺癌38例,良性病变18例。~(18)F-FDG PET/CT对胰腺癌诊断的灵敏度、特异度、阳性预测值、阴性预测值及准确率分别为88.3%、80.2%、93.0%、82.7%及85.6%;增强CT诊断的灵敏度、特异度、阳性预测值、阴性预测值及准确率分别为74.1%、68.6%、80.9%、63.2%、72.6%,~(18)F-FDG PET/CT的诊断效能均高于增强CT。PET/CT联合增强CT对胰腺病变诊断的灵敏度为100.0%,特异度为90.9%,准确率为95.2%。~(18)F-FDG PET/CT与最终诊断具有较高的一致性(k=0.705),增强CT的诊断结果与最终诊断结果中度一致(k=0.409),两者联合具有极好的一致性(k=0.816)。结论~(18)F-FDG PET/CT对胰腺癌的诊断具有较高的灵敏度及特异性,~(18)F-FDG PET/CT联合增强CT可以明显提高诊断的灵敏度、特异性及准确率。     

Side-by-side reading of PET and CT scans in oncology: which patients might profit from integrated PET/CT?

Purpose Most early publications on integrated positron emission tomography/computed tomography (PET/CT) devices have reported the new scanner generation to be superior to conventional PET. However, few of these studies have analysed the situation where, in addition to PET, a current CT scan is available for side-by-side viewing. This fact is important, because combined PET/CT or a software-based fusion of the two modalities may improve diagnosis only in cases where side-by-side reading of PET and CT data does not lead to a definitive diagnosis. The aim of this study was to analyse which patients will profit from integrated PET/CT in terms of lesion characterization.Methods A total of 328 consecutively admitted patients referred for PET in whom a current CT scan was available were included in the study. The localization of all pathological PET lesions, as well as possible infiltration of adjacent anatomical structures, was assessed.Results Of 467 pathological lesions, 94.0% were correctly assessed with respect to localization and infiltration by either conventional PET alone (51.6%) or combined reading of PET and the already existing CT scans (42.4%). Hence, in only 6.0% of all lesions, affecting 6.7% of all patients, could evaluation have profited from integrated PET/CT.Conclusion We conclude that side-by-side viewing of PET and CT scans is essential, as in 42.4% of all cases, combined viewing was important for a correct diagnosis in our series. In up to 6.7% of patients, integrated PET/CT might have given additional information, so that in nearly 50% of patients some form of combined viewing of PET and CT data is needed for accurate lesion characterization.     

PET/CT with intravenous contrast can be used for PET attenuation correction in cancer patients

Purpose If the CT scan of a combined PET/CT study is performed as a full diagnostic quality CT scan including intravenous (IV) contrast agent, the quality of the joint PET/CT procedure is improved and a separate diagnostic CT scan can be avoided. CT with IV contrast can be used for PET attenuation correction, but this may result in a bias in the attenuation factors. The clinical significance of this bias has not been established. Our aim was to perform a prospective clinical study where each patient had CT performed with and without IV contrast agent to establish whether PET/CT with IV contrast can be used for PET attenuation without reducing the clinical value of the PET scan.Methods A uniform phantom study was used to document that the PET acquisition itself is not significantly influenced by the presence of IV contrast medium. Then, 19 patients referred to PET/CT with IV contrast underwent CT scans without, and then with contrast agent, followed by an ¹⁸F-fluorodeoxyglucose whole-body PET scan. The CT examinations were performed with identical parameters on a GE Discovery LS scanner. The PET data were reconstructed with attenuation correction based on the two CT data sets. A global comparison of standard uptake value (SUV) was performed, and SUVs in tumour, in non-tumour tissue and in the subclavian vein were calculated. Clinical evaluation of the number and location of lesions on all PET/CT scans was performed twice, blinded and in a different random order, by two independent nuclear medicine specialists.Results In all patients, the measured global SUV of PET images based on CT with IV contrast agent was higher than the global activity using non-contrast correction. The overall increase in the mean SUV (for two different conversion tables tested) was 4.5±2.3% and 1.6±0.5%, respectively. In 11/19 patients, focal uptake was identified corresponding to malignant tumours. Eight out of 11 tumours showed an increased SUV_max (2.9±3.1%) on the PET images reconstructed using IV contrast. The clinical evaluation performed by the two specialists comparing contrast and non-contrast CT attenuated PET images showed weighted kappa values of 0.92 (doctor A) and 0.82 (doctor B). No contrast-introduced artefacts were found.Conclusion This study demonstrates that CT scans with IV contrast agent can be used for attenuation correction of the PET data in combined modality PET/CT scanning, without changing the clinical diagnostic interpretation.     

Application of positron emission tomography/computed tomography in radiation treatment planning for head and neck cancers

18-fluorodeoxygluocose positron emission tomography/computed tomography (¹⁸FDG-PET/CT) provides significant information in multiple settings in the management of head and neck cancers (HNC). This article seeks to define the additional benefit of PET/CT as related to radiation treatment planning for squamous cell carcinomas (SCCs) of the head and neck through a review of relevant literature. By helping further define both primary and nodal volumes, radiation treatment planning can be improved using PET/CT. Special attention is paid to the independent benefit of PET/CT in targeting mucosal primaries as well as in detecting nodal metastases. The utility of PET/CT is also explored for treatment planning in the setting of SCC of unknown primary as PET/CT may help define a mucosal target volume by guiding biopsies for examination under anesthesia thus changing the treatment paradigm and limiting the extent of therapy. Implications of the use of PET/CT for proper target delineation in patients with artifact from dental procedures are discussed and the impact of dental artifact on CT-based PET attenuation correction is assessed. Finally, comment is made upon the role of PET/CT in the high-risk post-operative setting, particularly in the context of radiation dose escalation. Real case examples are used in these settings to elucidate the practical benefits of PET/CT as related to radiation treatment planning in HNCs.     

FDG-PET/CT in restaging of patients with recurrent breast cancer: possible impact on staging and therapy

We aimed to compare the value of combined positron emission tomography (PET)/CT, PET+CT (viewed side by side), CT alone and PET alone concerning the rTNM stage and influence on therapy in patients with recurrent breast cancer. 44 patients with suspicion of recurrent breast cancer underwent whole-body [18F]-2-fluoro-2-deoxy-d-glucose (FDG)-PET/CT. Images of combined PET/CT, PET+CT, PET alone and CT alone were evaluated by four blinded reader teams. Diagnostic accuracies and influence on therapy were compared. Histology and a mean clinical follow up of 456 days served as the standard of reference. Differences between the staging procedures were tested for statistical significance by McNemar's test. Overall TNM tumour stage was correctly determined in 40/44 patients with PET/CT, in 38/44 with PET+CT, in 36/44 with PET alone and in 36/44 patients with CT alone. No statistically significant difference was detected between all tested imaging modalities. PET/CT changed the therapy in two patients compared with PET+CT, in four patients compared with PET alone and in five patients compared with CT alone. Combined PET/CT appeared to be more accurate in assessing the rTNM and showed a moderate impact on therapy over PET and CT. Minor improvements were noted when compared with PET+CT. Experienced readers might therefore be able to provide accurate staging results for further therapy from separately acquired studies.     

Dual-modality PET/CT instrumentation—Today and tomorrow

Positron emission tomography (PET) has proven to be a clinically valuable imaging modality, particularly for oncology staging and therapy follow-up. The introduction of combined PET/CT imaging has helped address challenging imaging situations when anatomical information on PET-only was inadequate for accurate lesion localization. After a decade of PET/CT these combined systems have matured technically. Today, whole-body oncology staging is available with PET/CT in 15 min, or less. This review details recent developments in combined PET/CT instrumentation and points to implications for major applications in clinical oncology.     

18F-FDG PET/CT的特点及其在肿瘤诊断中的应用

最近几年,具有高性能PET和CT的同机PET/CT已投入临床,其在肿瘤学中的应用呈迅速增长之势.加入高档CT的PET较之传统的PET在技术和临床方面具有明显优势.CT扫描一方面为PET提供了快速、准确的衰减校正数据,大大缩短采集时间,另一方面为PET图像提供了精确的解剖定位,使结果更加肯定,但引入CT的PET扫描也带来了一些技术上的新问题.PET/CT在头颈、腹盆肿瘤具有明显优势,即使在生理运动影响较大的胸部也取得了满意的效果.初步临床研究表明,PET/CT较之单独CT或PET在临床肿瘤学中具有明显优势,PET/CT融合显像对肿瘤患者和临床医生具有越来越重要的价值.     

The diagnostic value of PET/CT in recurrence and distant metastasis in breast cancer patients and impact on disease free survival

Aim of work

To detect the diagnostic value of PET/CT in breast cancer patients. We compared the performance of PET/CT with that of conventional imaging in detection of recurrence and distant metastasis and evaluated the impact PET/CT results have on disease free survival.

Materials and methods

We retrospectively studied 50 patients with breast cancer with clinical suspicion of recurrent or metastatic lesion and who underwent PET/CT and conventional imaging procedures. The imaging results were retrospectively compared with histopathology and clinical follow-up as a reference standard.

Results

PET/CT detected distant metastases with a sensitivity of 97% and a specificity of 93%. In contrast, the sensitivity and specificity of combined conventional imaging procedures were 75% and 73%, respectively, disease-free survival was significantly shorter in the 34 M1-PET/CT patients than in the 14 M0-PET/CT patients (log-rank P = 0.002) also PET/CT detected recurrence in 1 patient with equivocal mammographic findings.

Conclusion

In breast cancer, PET/CT is superior to conventional imaging procedures for detection of recurrence, distant metastases and PET/CT can be used to improve prediction of the clinical outcome of breast cancer patients.     

PET/CT: form and function

Functional imaging with positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of malignant disease, image-guided therapy planning, and treatment monitoring. PET with the labeled glucose analogue fluorine 18 fluorodeoxyglucose (FDG) is a relatively recent addition to the medical technology for imaging of cancer, and FDG PET complements the more conventional anatomic imaging modalities of computed tomography (CT) and magnetic resonance imaging. CT is complementary in the sense that it provides accurate localization of organs and lesions, while PET maps both normal and abnormal tissue function. When combined, the two modalities can help both identify and localize functional abnormalities. Attempts to align CT and PET data sets with fusion software are generally successful in the brain; other areas of the body is more challenging, owing to the increased number of degrees of freedom between the two data sets. These challenges have recently been addressed by the introduction of the combined PET/CT scanner, a hardware-oriented approach to image fusion. With such a device, accurately registered anatomic and functional images can be acquired for each patient in a single scanning session. Currently, over 800 combined PET/CT scanners are installed in medical institutions worldwide, many of them for the diagnosis and staging of malignant disease and increasingly for monitoring of the response to therapy. This review will describe some of the most recent technologic developments in PET/CT instrumentation and the clinical indications for which combined PET/CT has been shown to be more useful than PET and CT performed separately.     

Positron emission tomography/computed tomography for staging and restaging of head and neck cancer: comparison with positron emission tomography read together with contrast-enhanced computed tomography

This retrospective study aimed to describe the differences between image readings done with combined positron emission tomography/computed tomography (PET/CT) and PET read together with contrast-enhanced CT (ceCT) in patients with squamous cell carcinoma of the head and neck. In 46 patients, no differences were found between the two readings for assessing infiltration of adjacent structures (P=.63), transgression of the midline (P=.67), lymph node involvement (P=.32), and T- and N stage. PET/CT and PET read together with ceCT have comparable diagnostic yield.     

呼吸运动伪影的校正及其与肺部SUV的关系

ET/CT在疾病诊断和疗效评价上起着重要作用, 但是呼吸运动伪影给病变的诊断及治疗带来困扰, 临床有多种方法可以用来对呼吸运动伪影进行校正, 其中应用最广泛的是呼吸门控技术。其对呼吸运动伪影校正后可以明显提高肺部病变的最大标准化摄取值, 从而提高图像质量及诊断的准确性。