Imaging of gynecologic malignancies with FDG PET–CT: case examples,physiolocic activity,and pitfalls

The utilization of 2-[fluorine 18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in combination with computed tomography (CT) in the assessment of gynecologic malignancies has been rapidly growing in recent years; however, its role in clinical practice has yet to be established. A number of pitfalls are commonly encountered, including normal physiologic activity in bowel loops and blood vessels, or focal retained activity in ureters and urinary bladder. Increased uptake has also been reported in many benign pelvic processes and in premenopausal patients; endometrial activity changes cyclically, whereas increased ovarian uptake may be functional. FDG PET–CT has an emerging role in staging nodal disease and in the evaluation of local recurrence or peritoneal spread of gynecologic malignancies and is also useful in monitoring response to therapy and in long-term follow-up. FDG PET–CT is most suitable in patients with high tumor markers and negative or uncertain conventional imaging data. Patient preparation, proper scanning protocol, combined assessment of PET and CT data, and the evaluation of conventional imaging findings are essential to define disease and to avoid diagnostic pitfalls.     

PET-CT detection of abdominal recurrence of ovarian cancer: radiologic–surgical correlation

The diagnosis of recurrent ovarian cancer can be difficult on cross-sectional imaging, and variable sensitivities and specificities have been reported for positron emission tomography (PET). Combined functional and anatomic imaging with PET plus computed tomography (CT) potentially allows for improved detection of tumor masses. We investigated the sensitivity, specificity, and accuracy of PET-CT for the diagnosis of recurrent ovarian cancer. Sixteen women with previously treated ovarian cancer underwent imaging on a combined PET-CT scanner followed by surgery to assess for possible recurrent disease. The fused PET-CT images were retrospectively reviewed for recurrent disease, and the results of PET-CT were compared with the operative notes. Eleven of the 16 patients had recurrent disease at surgery. The sensitivity, specificity, and accuracy of PET-CT for disease detection on a per-patient basis were 72.7%, 40%, and 62.5%, respectively. For cases of malignant adenopathy (n = 7), 100% were detected on PET-CT. For peritoneal lesions no larger than 1 cm (n = 23), 13% were detected on PET-CT. For peritoneal lesions larger than 1 cm (n = 8), 50% were detected on PET-CT. The sensitivity of PET-CT for recurrent ovarian cancer is moderate in patients with low volume disease. A trial involving a larger number of patients with a spectrum of disease volumes is necessary to determine the impact of PET-CT in clinical practice.     

State-of-the-art imaging of peritoneal carcinomatosis

Imaging studies are essential in the evaluation of patients with suspected or known peritoneal malignancy. Despite major advances in imaging technology in the last few years, the early and adequate detection of a peritoneal dissemination remains challenging because of the great variety in size, morphology and location of the peritoneal lesions. New therapeutic approaches in peritoneal-based neoplasms combining cytoreductive surgery and peritonectomy with hyperthermic intraoperative chemotherapy (HIPEC) suggest improved long-term survival, provided that a complete (macroscopic) cytoreduction is achieved. The preoperative radiological assessment of the extent and distribution of peritoneal involvement plays a vital role in the patient selection process. Despite its known limited accuracy in detecting small peritoneal lesions and the involvement of the small bowel/mesentery, contrast-enhanced MDCT remains the standard imaging modality in the assessment of peritoneal carcinomatosis. MRI, especially with diffusion-weighted images, and FDG-PET/CT are promising methods for the evaluation of peritoneal carcinomatosis with superior results in recent studies, but still have a limited role in selected cases because of high costs and limited availability. Generally, to obtain the most precise readings of peritoneal carcinomatosis, an optimized examination protocol and dedicated radiologists with a deep knowledge of peritoneal pathways and variable morphologies of peritoneal disease are required.     

18F-FDG PET-CT在多浆膜腔积液探查肿瘤原发灶中的价值

目的 探讨18F脱氧葡萄糖正电子发射体层摄影术（18 F-FDG PET-CT）全身显像在可疑恶性肿瘤所致多浆膜腔积液中的应用价值.方法 回顾性分析2006年6月至2013年6月期间84例以多浆膜腔积液为首发症状临床可疑恶性肿瘤患者的PET CT显像资料,并将显像结果与病理及临床随访结果进行对比分析.结果 84例患者中有62例经病理及临床随访证实为恶性.84例多浆膜腔积液患者中胸水＋腹水42例,胸水＋心包积液30例,腹水＋心包积液6例,胸水＋腹水＋心包积液6例,胸水合并腹水以卵巢癌、腹膜癌及肺癌多见,胸水合并心包积液以肺癌多见.62例恶性肿瘤患者中通过PET-CT检查明确原发灶49例,检出率为79.0％.有19例最终排除恶性肿瘤诊断,另3例未能明确诊断.以病理及临床随访诊断结果为标准,通过绘制ROC曲线SUVmax取3.6为截断值时SUV-max用于诊断多浆膜腔积液患者的可疑原发灶良恶性的准确度最高,敏感性为90.3％,特异性为81.8％,阳性预测值93.1％,阴性预测值65.2％.结论 18F-FDG PET-CT全身显像在不明原因多浆膜腔积液中有重要价值,尤其是可疑恶性肿瘤者,能在定性诊断的基础上明确定位并准确分期,指导治疗.     

PET组合融合成像在分化型甲状腺癌复发和转移中的应用进展

甲状腺癌是最常见的内分泌系统恶性肿瘤之一，其中分化型甲状腺癌约占甲状腺癌发病率的90%以上，预后良好。但中国甲状腺癌患者5年相对生存率与一些发达国家差距较大。早期、准确地发现复发性疾病并应用适当的治疗策略，可改善复发性疾病患者的预后。因此，早期发现这些病人的复发和转移是至关重要的。随着诊断技术从系统向分子水平的过渡，多模态分子成像的作用越来越重要。PET能提供肿瘤细胞的功能学信息，而CT、MRI则能提供肿瘤的解剖学信息。功能成像技术和解剖学成像技术相结合能够实现优势互补，对于疾病复发和转移的诊断意义重大。随着近年来PET-CT在分化型甲状腺癌诊断、分期、疗效及预后评估上都较常规影像学检查更具优势，而PET-MRI是继PET-CT之后又一项优秀的多模态成像技术，因其软组织高分辨率和多序列多参数成像特性，所发挥的作用也愈发重要。因此，本文就PET-CT和PET-MRI在分化型甲状腺癌术后复发/转移中临床应用及未来前景进行综述。      

^18F—FDG PET—CT对胆囊癌的诊断价值

目的 探讨^18F-FDG PET—CT在胆囊癌诊断、分期、术后再分期中的应用价值。方法 通过半定量方法对6例胆囊癌病人的^18F-FDG PET—CT影像资料图像进行回顾性分析。结果 3例病人经^18F-FDG PET—CT明确诊断且无远处转移,经临床病理证实为胆囊腺癌;3例胆囊癌术后病人^18F-FDG PET—CT均发现常规影像学方法未发现的转移病灶。结论 ^18F-FDG PET—CT对胆囊癌的诊断有一定的价值,对胆囊癌术后再分期有常规影像学检查无可比拟的作用。     

Staging of colon cancer: whole-body MRI vs. whole-body PET-CT—initial clinical experience

Background  To assess the accuracy of whole-body MR imaging (WB-MRI) in comparison with whole-body [18^F]-2-fluoro-2-deoxy-d-glucose (FDG) PET-CT in staging patients with diagnosed colorectal carcinoma (CRC). Methods  Twenty consecutive patients with previously diagnosed CRC underwent WB-MRI (3T) and PET-CT for staging of lymph node (N) and distant metastases (M). Evaluation was done according to the American Joint Committee on Cancer Staging Criteria. MR images were evaluated by two radiologists while PET-CT images by one radiologist and one nuclear medicine physician. Histology and/or a clinical follow-up of 3–6 months served as standard of reference. Results  Lymph node involvement was determined in 10/20 cases as N-positive in WB-MRI and in 15/20 in PET-CT. M-stage was evaluated for liver metastases (27 lesions in 15 patients with WB-MRI, 23/15 patients with PET-CT), lung (19/5 patients with WB-MRI, 25/7 patients with PET-CT), and bone (9/3 patients with WB-MRI, 9/3 patients with PET-CT). Two patients showed peritoneal implants and three patients demonstrated local recurrence at the surgery site on both modalities. No brain metastases were found. Conclusions  WB-MRI is a feasible method for examining colon cancer patients but cannot displace the present role of PET-CT.     

The role of FDG-PET imaging in the management of lymphoma

Positron emission tomography (PET) imaging using [F-18]fluorodeoxyglucose (FDG) has become a useful imaging modality in the staging and treatment evaluation algorithm for lymphoma, providing unique metabolic information. Increased FDG uptake in lymphoma tumor masses is a function of increased anaerobic metabolism and longer residence time of FDG in malignant cells relative to most normal tissues. The information provided by FDG-PET appears to result in greater sensitivity compared to anatomic imaging modalities, particularly computed tomography (CT). Over several decades CT has been the principal imaging modality for the staging and restaging of lymphoma, although it can have significant shortcomings stemming from its sized-based criteria, particularly in the post-therapy setting. Gallium-67 (Ga-67) scintigraphy has played an important role in monitoring response to therapy; however, the sensitivity of Ga-67 depends on histologic subtype of lymphoma, size, and location of disease. Published results suggest that FDG-PET is superior to Ga-67 imaging and equal or superior to CT for the detection of nodal and extranodal lymphoma at initial staging. Furthermore, persistent FDG uptake during and after chemotherapy has a high sensitivity and specificity for prediction of subsequent relapse. While in some cases FDG-PET imaging can yield findings that prompt a change in treatment strategy, prospective studies are necessary to better establish the ability of routine FDG-PET imaging to impact therapeutic outcomes for patients with lymphoma.     

Positron emission tomography-computed tomography protocol considerations for head and neck cancer imaging

Positron emission tomographic-computed tomographic (PET-CT) imaging of patients with primary head and neck cancers has become an established approach for staging and restaging, as well as radiation therapy planning. The inherent co-registration of PET and CT images made possible by the integrated PET-CT scanner is particularly valuable in head and neck cancer imaging due to the complex and closely situated anatomy in this part of the body, the varied sources of physiologic and benign 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) tracer uptake that occurs in the neck, and the varied and complex posttreatment appearance of the neck. Careful optimization of both the CT and the PET portion of the examination is essential to insure the most accurate and clinically valuable interpretation of these examinations.     

18F-FDG Cardiac Studies for Identifying Ischemic Memory

Myocardial ischemia is associated with profound changes in substrate utilization by the myocardium for energy production. This change occurs with the onset of ischemia, but persists much longer, perhaps for several hours or even days after an episode of myocardial ischemia, which is termed ischemic memory. Recently, radiolabeled glucose analogue (Fluorine-18 labeled deoxyglucose, ¹⁸FDG) and free acid analogue (??-methyl-p-¹²³I-iodophenyl-pentadecanoic acid, ¹²³I-BMIPP) have been investigated to detect myocardial ischemia in stable coronary artery disease (CAD) or suspected acute coronary syndrome (ACS). These studies demonstrate that BMIPP imaging holds promise for evaluation of patients with suspected ACS in the emergency department. Exercise ¹⁸FDG imaging offers several potential advantages over conventional stress-rest perfusion imaging for the detection of CAD. Furthermore, ischemia-induced ¹⁸FDG uptake may persist for several to 24?hours in patients with stress-induced myocardial ischemia. Therefore, ¹⁸FDG may also be a useful memory marker in detection of antecedent myocardial ischemia in suspected ACS. However, some important issues about ¹⁸FDG ischemic imaging need to be further investigated. In this article the advances of myocardial ischemic imaging with ¹⁸FDG are reviewed. Several unresolved issues and the perspective of this modality are also discussed.     

The Role of Radionuclide Imaging in Congenital Heart Disease

Purpose of Review

Congenital heart disease is a growing healthcare issue since the majority of children who underwent surgical repair are now surviving into adult life. However, these patients are generally fixed but not cured and many will go on to develop significant morbidity as adults. The purpose of this review is to discuss the utility of radionuclide imaging in the management of these patients with a focus on the longer-term follow-up into adult life.

Recent Findings

Radionuclide imaging is a relatively niche tool in the management of congenital heart disease patients and many of the techniques have been around for decades. What is new is the application of techniques such as fluorodeoxyglucose (FDG) imaging for endocarditis and device infection using anatomic colocalization by MR-PET or PET-CT. There is also growing interest in the quantitative assessment of coronary blood flow with tracers such as rubidium that are available without the need for a cyclotron on site. This is likely to be very useful in the management of patients with coronary anomalies or surgically re-implanted coronary arteries.

Summary

Radionuclide imaging has specific but rather limited application to congenital heart disease at the current time. With the development of new molecular imaging agents, low-dose protocols, and the wider availability of hybrid imaging modalities, we suggest that the ground is prepared for a resurgence of interest in the application of these techniques to the population of patients living with congenital heart disease.

     

Best Practices in PET/CT: Consensus on Performance of Positron Emission Tomography–Computed Tomography

Positron emission tomography-computed tomography (PET-CT) using the glucose metabolism tracer 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) has become a widespread and preferred imaging modality for evaluating most cancers. Since commercial PET-CT scanners became available in 2001, there has been rapid dissemination of this hybrid imaging modality and PET-CT scanners have largely replaced stand-alone PET scanners. How PET-CT scans are performed and applied to cancer management has varied considerably, in part reflecting the varied background of the practice settings and training experience of the physicians performing and interpreting the PET-CT studies. Combined PET/CT with FDG has become the gold standard in oncologic imaging by accurately defining anatomy and function of many tumors. From April 2-4, 2008, a focus group composed of physicians and technologists from different practice settings and training backgrounds entitled "Best Practices in PET/CT Symposium" was held in Sonoma, California. The symposium focused on optimization of PET-CT protocols but also included other pertinent topics related to PET-CT imaging in oncology. This article summarizes areas of consensus reached by the group regarding many of the discussion topics. The summary consensus covered in this article is meant to provide direction for future discussions on how to improve the application of this hybrid modality to patient care.     

Role of PET/PET CT in the staging and restaging of thoracic oesophageal cancer and gastro-oesophageal cancer: a literature review

Background Current evidence for the use of FDG PET/PET-CT in staging thoracic oesophageal and GOJ cancer is reviewed. Methods PubMed, Medline, Embase (1988–November 2006) and the Cochrane database identifed studies in which FDG PET and PET CT were used for the assessment of thoracic and GOJ cancer. Results Conventional assessment remains the mainstay for evaluating the primary site. EUS is used for assessing the primary site, but when EUS is incomplete or not tolerated FDG PET CT is invaluable. The major of advantage of FDG PET CT lies in the ability to detect metastatic disease beyond the celiac axis. There is growing evidence to show that FDG PET CT is useful for assessment of treatment response. FDG PET CT will also detect other occult primary cancers. Conclusions The contribution of FDG PET CT to the investigation of patients with primary thoracic oesophageal and GOJ cancer has resulted in improved staging, so providing the ability to optimise treatment.     

^18F—FDG PET—CT显像在肾癌原发灶及转移灶诊断中的价值

[目的]探讨18F-FDG PET-CT显像在肾癌原发灶及转移病灶诊断中的价值.[方法]回顾性分析35例临床诊断为肾癌患者的全身18F-FDG PET-CT及病理结果,比较PET-CT与增强CT两者对肾癌及转移病灶的诊断价值.[结果]35例中,经原发灶手术病理证实为肾癌30例.其余5例因18F-FDG PET-CT显像发现远处转移未行原发灶手术治疗,仅取转移部位病检确诊,分别行DSA肿瘤栓塞术、免疫治疗及靶向药物治疗.18F-FDG PET-CT检查阳性29例,敏感度82.9% ,CT平扫加增强检查阳性33例,敏感度94.3%,转移病灶共16处, 腹膜后淋巴结转移3处,肺转移3处,肾静脉癌栓形成1处,骨转移2处,肝转移1处,肾上腺、右侧锁骨上淋巴结、纵隔淋巴结、双肺门淋巴结转移1处,右侧胸壁转移1处,软组织转移1处,而CT平扫加增强仅发现1处下腔静脉癌栓形成,1处肝转移.[结论]18F-FDG PET-CT对诊断原发性肾癌的敏感性不如CT,但对远处转移的诊断优于CT,对肾癌的分期及治疗方案的选择有重要意义.     

Anal carcinoma: FDG PET/CT in staging, response evaluation, and follow-up

The role of FDG PET/CT in anal cancer is becoming increasingly important. At the time of initial staging, FDG PET/CT can detect the primary site of disease more frequently than CT, is sensitive for nodal and metastatic spread and alters staging in a significant number of patients. Indeed, the NCCN guidelines for anal cancer published in April 2012 recommend FDG PET/CT for therapy planning. Metabolic activity of primary anal cancer at presentation is a potential biomarker for predicting prognosis, treatment response and survival. More intensely FDG-avid primary malignancy is associated with a higher incidence of disease spread. Metabolic response following chemoradiotherapy is associated with improved survival. The aim of this paper is to provide an up-to-date pictorial review of FDG PET/CT in anal cancer at the time of staging and to illustrate its utility for determining response to therapy and detecting recurrent disease.     

Comparison of [18F]Fluorodeoxyglucose Positron Emission Tomography and Contrast-Enhanced Ultrasound for Evaluation of Hepatic Alveolar Echinococcosis Activity

The mean gray-scale ratio of the infiltrating zone of a lesion to the surrounding normal liver tissue was evaluated on the basis of contrast enhancement of the infiltration and proliferation zones of a hepatic alveolar echinococcosis lesion. The results were compared with the maximum standardized uptake value (SUVmax) of [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG PET-CT), and the application of contrast-enhanced ultrasound in evaluating hepatic alveolar echinococcosis activity is discussed. The 36 patients with hepatic alveolar echinococcosis recruited underwent contrast-enhanced ultrasound and [¹⁸F]FDG PET-CT. A total of 39 lesions were found in the 36 patients. The results indicated that in 87.2% of the cases, the two methods yielded the same diagnosis, whereas in 12.8% of cases, the diagnoses obtained with the two methods were inconsistent. The statistical results revealed that contrast-enhanced ultrasound and [¹⁸F]FDG PET-CT have good inter-rater reliability in determining the activity of hepatic alveolar echinococcosis (κ?=?0.756, p < 0.01).     

~(18)F-FDG PET-CT显像对恶性淋巴瘤诊断和分期中的临床应用价值

目的探讨18F-FDG PET-CT显像在恶性淋巴瘤诊断、疗效评价及临床分期中的应用价值。方法对30例疑诊为淋巴瘤并进行18F-FDG PET-CT显像28例经病理证实为淋巴瘤,其中HD6例,NHL22例。图像分析采用视图分析及测量病灶平均标准摄取值方法相结合。结果 30例疑诊淋巴瘤患者中,14例治疗前行PET-CT检查,11例确诊为淋巴瘤,2例假阳性,1例假阴性;5例手术治疗后,2例术后复发及转移;11例放疗/化疗的患者,4例复发,4例见局部有病灶残存,3例未见异常;5例患者于治疗前及放化疗后检查,4例肿瘤明显受抑制1。8F-FDG PET-CT诊断符合率为93.3%。检测淋巴瘤病灶敏感性为89.4%。特异性为95.5%。结论 18F-FDG PET-CT显像对淋巴瘤病灶有较高的敏感性、特异性,有助于临床更准确的分期从而指导治疗。     

Radiologic Responses in Cynomolgus Macaques for Assessing Tuberculosis Chemotherapy Regimens

Trials to test new drugs currently in development against tuberculosis in humans are impractical. All animal models to prioritize new regimens are imperfect, but nonhuman primates (NHPs) infected with Mycobacterium tuberculosis develop active tuberculosis (TB) disease with a full spectrum of lesion types seen in humans. Serial 2-deoxy-2-[¹⁸F]-fluoro-d-glucose (FDG) positron emission tomography (PET) with computed tomography (CT) imaging was performed on cynomolgus macaques during infection and chemotherapy with individual agents or the four-drug combination therapy most widely used globally. The size and metabolic activity of lung granulomas varied among animals and even within a single animal during development of disease. Individual granulomas within untreated animals had highly local and independent outcomes, some progressing in size and FDG uptake, while others waned, illustrating the highly dynamic nature of active TB. At necropsy, even untreated animals were found to have a proportion of sterile lesions consistent with the dynamics of this infection. A more marked reduction in overall metabolic activity in the lungs (decreased FDG uptake) was associated with effective treatment. A reduction in the size of individual lesions correlated with a lower bacterial burden at necropsy. Isoniazid treatment was associated with a transient increase in metabolic activity in individual lesions, whereas a net reduction occurred in most lesions from rifampin-treated animals. Quadruple-drug therapy resulted in the highest decrease in FDG uptake. The findings of PET-CT imaging may provide an important early correlate of the efficacy of novel combinations of new drugs that can be directly translated to human clinical trials.