PET imaging of musculoskeletal tumours with fluorine-18 α-methyltyrosine: comparison with fluorine-18 fluorodeoxyglucose PET

Fluorine-18 labelled !-methyltyrosine (FMT) was developed for positron emission tomography (PET) imaging, and its potential for clinical application in patients with brain tumours has been demonstrated. This is the first trial to compare FMT with ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) for the evaluation of musculoskeletal tumours. Seventy-five patients were examined with both FMT- and FDG-PET within a 2-week period. Imaging findings were visually inspected in conjunction with computed tomography and/or magnetic resonance imaging, and standardized uptake values (SUVs) for both FMT and FDG in lesions were also generated and compared with histological findings. A significant correlation between FMT and FDG SUVs was found for all lesions (r=0.769, P<0.0001), and mean values for malignant tumours were significantly higher than those for benign lesions in both FMT- and FDG-PET. The diagnostic sensitivities and specificities for malignancy were 72.7% and 84.9%, respectively, using FMT with a cut-off SUV of 1.2, and 72.7% and 66.0%, respectively, using FDG with a cut-off SUV of 1.9. The resultant accuracy with FMT was 81.3%, higher than that for FDG (68.0%), and the difference with respect to specificity was significant (L²cal=5.0625, P<0.05). On the other hand, while a significant correlation was found between malignant tumour grade and SUV with both FMT- (A=0.656) and FDG-PET (A=0.815), only the latter demonstrated significant differences among grades I, II and III. FMT and FDG for PET appear equally effective at detecting musculoskeletal tumours. In evaluating musculoskeletal tumours, FMT may be superior to FDG in the differentiation between benign and malignant tumours, while FDG may be the better choice for non-invasive malignancy grading.     

¹¹C-choline and F-18 FDG PET/CT images of hemangioblastoma

We present the F-18 FDG and 11C-choline PET/CT images obtained in 2 cases of hemangioblastoma. Hemangioblastoma is a highly vascular benign tumor that typically arises in the cerebellum or spine. The characteristic findings of a hemangioblastoma on both CT and MR include a peripherally located cerebellar lesion with a central cystic region and a peripherally enhanced nodule. In both patients, the uptake in the lesion was relatively low on the F-18 FDG PET/CT images and relatively high on the 11C-choline PET/CT images.     

Can multimodality imaging using 18F-FDG/18F-FLT PET/CT benefit the diagnosis and management of patients with pulmonary lesions?

Purpose

Dual-tracer, ¹⁸F-fluorodeoxyglucose and ¹⁸F-fluorodeoxythymidine (¹⁸F-FDG/¹⁸F-FLT), dual-modality (positron emission tomography and computed tomography, PET/CT) imaging was used in a clinical trial on differentiation of pulmonary nodules. The aims of this trial were to investigate if multimodality imaging is of advantage and to what extent it could benefit the patients in real clinical settings.

Methods

Seventy-three subjects in whom it was difficult to establish the diagnosis and determine management of their pulmonary lesions were prospectively enrolled in this clinical trial. All subjects underwent ¹⁸F-FDG and ¹⁸F-FLT PET/CT imaging sequentially. The images were interpreted with different strategies as either individual or combined modalities. The pathological or clinical evidence during a follow-up period of more than 22?months served as the standard of truth. The diagnostic performance of each interpretation and their impact on clinical decision making was investigated.

Results

¹⁸F-FLT/¹⁸F-FDG PET/CT was proven to be of clinical value in improving the diagnostic confidence in 28 lung tumours, 18 tuberculoses and 27 other benign lesions. The ratio between maximum standardized uptake values of ¹⁸F-FLT and ¹⁸F-FDG was found to be of great potential in separating the three subgroups of patients. The advantage could only be obtained with the full use of the multimodality interpretation. Multimodality imaging induced substantial change in clinical management in 31.5% of the study subjects and partial change in another 12.3%.

Conclusion

Multimodality imaging using ¹⁸F-FDG/¹⁸F-FLT PET/CT provided the best diagnostic efficacy and the opportunity for better management in this group of clinically challenging patients with pulmonary lesions.     

18F-FLT PET/CT与18F-FDG PET/CT在鼻咽癌诊断和分期中的应用比较

目的 通过与18F-FDG PET/CT显像对比,探讨18 F-FLT PET/CT检测鼻咽癌原发灶和颈部淋巴结转移灶的可行性.方法 12例初治且经病理确诊的鼻咽癌患者(年龄22～62岁)自愿进入该前瞻性临床研究.每位患者先行18F-FDG PET/CT检查,次日行18F-FLF PET/CT检查.至少有2位核医学科和放射科医师阅片,比较18F-FDG PET/CT和18F-FLT PET/CT图像,采用ROI技术计算鼻咽肿瘤、颈部淋巴结转移灶、正常组织对18F-FDG、18F-FLT的SUVmax、SUVmean和MTV.采用非参数Wilcoxon秩和检验比较组间摄取和MTV差异.结果 12例鼻咽癌患者病灶均明显摄取18F-FLT.18F-FLT PET/CT和18F-FDG PET/CT均可准确诊断该组病例,二者对原发灶和淋巴结转移灶的检测结果无明显差别.鼻咽癌病灶的18F-FDG和18F-FLT SUVmax分别为10.7±5.8和6.0±2.4,SUVmean分别为5.8±3.0和3.6±1.5;SUVmax和SUVmean组间差异均有统计学意义(Z=-2.589和-2.353,P均＜0.05),而 MTV在18F-FDG和8F-FLT PET/CT 2种显像方法之问的差异无统计学意义(15.9±9.2和18.1±11.1;Z=-0.786,P＞0.05).6例有颈部淋巴结转移灶患者的SUVmax、SUVmean和MTV在2种显像方法间差异均无统计学意义(8.5±6.2比6.4±2.5、5.3±4.2比3.8±1.4、6.5 ±4.8比6.0±4.4;Z=-0.734、-0.734和-0.674,P均＞0.05).18F-FLT在颞叶摄取(SUVmax 0.7±0.3)明显低于18F-FDG(SUVmax 8.3±2.7;Z=-3.062,P＜0.01),其对于原发灶颅内浸润显示较18F-FDG更清晰.结论 18F-FLT PET/CT在鼻咽癌原发灶和淋巴结转移灶的诊断效能与18F-FDG PET/CT相当,对于显示原发灶的颅底附近侵犯更有利,其临床应用值得进一步研究.     

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。     

18F-FDG PET/CT探测恶性肿瘤软组织转移

笔者对11例患者16处软组织转移瘤(原发灶均经病理检查证实,软组织转移灶均经临床或病理检查证实)的PET/CT、临床资料进行回顾性分析,以提高对PET/CT在软组织转移瘤中价值的认识.     

结核病的18F-FDG PET/CT诊断辨析

结核病可以发生于全身多个脏器,且有多种多样的影像学表现,因此结核病与其他全身性疾病（尤其是肿瘤性疾病）的鉴别较为困难。18F-FDG PET/CT在全身性疾病的诊断中有一定优势,但工作中仍需结合患者的临床表现、实验室检查、病灶的CT征象及18F-FDG浓聚程度等信息进行辨析。笔者选取了临床实践中误诊的3个病例,分别为肠结核、肺结核和骨结核,分别从临床特征及18F-FDG PET/CT影像学表现等方面进行鉴别诊断,梳理诊断思路,以期为临床诊断提供帮助。     

18F-FDG PET/CT显像中的脂肪摄取

单纯PET图像难以区分脂肪或肌肉组织摄取^18F-脱氧葡萄糖（FDG）及是否为病理性摄取，CT特异性脂肪密度为其定性诊断提供了有力的佐证。现将本院在^18F-FDG PET/CT检查中的12例脂肪摄取病例报道如下。     

胆管癌的18F-FDG PET/CT诊断价值

目的 总结胆管癌18F-FDG PET/CT显像表现,提高胆管癌的诊断准确性.方法 回顾经病理或临床综合手段证实的53例胆道疾病的18F-FDG PET/CT表现,分析PET/CT诊断胆管癌的敏感性、特异性和准确性.结果 肝内胆管癌14例、近段胆管癌18例、中远段胆总管癌15例、胆管炎性病变或伴结石6例.肝内转移9例,腹腔及腹膜后淋巴结转移15例,椎体等远处转移3例.PET/CT诊断胆管癌的敏感性为95.7％、特异性为83.3％、准确性为94.3％.结论 18F-FDG PET/CT在胆管癌的诊断与鉴别诊断、分期、检测疗效及预后等具有独特的应用价值.     

核医学18F-FDG PET/CT报告书写规范

随着正电子发射计算机断层显像/计算机断层显像(positron emission tomography/computed tomography, PET/CT)临床应用的增加,氟-18标记氟代脱氧葡萄糖(flurodeoxyglucose,18F-FDG)PET/CT的诊断作用得到了临床的广泛认可.18F-FDG PE...     

Role of 18F-FDG PET/CT for detection of recurrence and metastases in renal cell carcinoma—are we underusing PET/CT?

PURPOSEThe aim of this study was to compare ¹⁸F-fluorodeoxyglucose positron emission tomography–computed tomography (¹⁸F-FDG PET/CT) scan with computed tomography (CT) scan for detecting recurrence and metastasis in renal cell carcinoma patients.METHODSThis retrospective study included patients from October 2013 to April 2017. Contrast-enhanced CT and PET/CT scans were compared and correlated with histopathology or/and follow-up studies.RESULTSSeventy-six patients, 60 males, were included. Lesions included primary renal, recurrent renal fossa lesions, lymph nodes, and distant metastatic lesions. Of 176 malignant lesions, CT detected 157 lesions; of which, 154 were true positive. Twenty-two false-negative lesions showed abnormal FDG uptake. CT scan had positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity, and accuracy of 98.0%, 37.1%, 87.5%, 81.2%, and 86.9%, respectively. All 176 lesions were PET/CT-positive. PET/CT had PPV, NPV, sensitivity, specificity, and accuracy of 100% each. The specificity and NPV of PET/CT were superior (P < .05). CONCLUSIONPET/CT appears more accurate than CT scan for detecting metastasis and recurrence in renal cell carcinoma patients.

Main points

• Positron emission tomography–computed tomography (PET/CT) has a significantly higher specificity and negative predictive value than CT scan for detection of metastasis and recurrence in patients with renal cell carcinoma.
• PET/CT scan is a better imaging technique compared to CT scan for follow-up imaging.

Renal cell carcinoma (RCC) is the most common solid kidney cancer. The incidence in Asian population is 1.1-6.0/100 000. World over, the 5-year survival rate is 68.4%.¹Localized RCC patients treated surgically usually have favorable outcomes. However, about 20%-40% patients later develop distant metastases. The main aim of postoperative follow-up is early detection of local recurrence and/or distant metastases. Post-surgery follow-up imaging is commonly done with conventional imaging modalities (CIM), mainly computerized tomography (CT) scan. These have certain limitations in assessing local recurrence due to postoperative changes such as fibrosis, adjacent organs occupying the space of the renal fossa, the presence of surgical clips causing metallic artifacts, and other such changes.About one-fourth of the patients are found to be metastatic at initial presentation, with very few (<5%) having single-site metastasis.²¹⁸F-fluorodeoxyglucose positron emission tomography–computed tomography scan (¹⁸F-FDG PET/CT) provides both anatomical details and functional information. PET/CT has better specificity (83%-100%) and sensitivity (80%-100%) as compared with CT scan or PET scan alone.^2-5 PET/CT is particularly useful for detection of involvement of lymph nodes. These are often not identified on CT scan (even though they are involved), which uses the 1 cm size criteria. CT interpretation of the renal fossa (post-nephrectomy) is difficult due to post-treatment changes. However, the metabolic activity of the tumor is not affected by these factors. Therefore, PET/CT can identify renal bed recurrence earlier and better than CT scan.³During the initial staging of RCC, contrast-enhanced CT scan of the chest, abdomen, and pelvis is the modality of choice. However, PET/CT scan images the whole body (head to toe) along with a contrast-enhanced CT examination in one procedure non-invasively. Since PET/CT relies on changes in metabolic activity of tissues, early detection of pathological areas is possible even before anatomic changes are apparent.³In cases with impaired renal function, a regional abdomino pelvic magnetic resonance imaging (MRI) is the preferred imaging choice due to its high soft-tissue resolution as many lesions can be missed on a non-contrast CT scan. Now in such cases, whole-body PET/CT scan can also be performed with non-contrast CT. Current guidelines do not recommend PET/CT as the initial diagnostic imaging modality of choice in RCC. However, studies have shown PET/CT to be better than conventional imaging like CT for detecting local recurrence and distant metastases.² Detection of distant metastases and accurate restaging of RCC are important because this can lead to changes in the treatment plan.We conducted this study to compare CT scan with PET/CT for detecting recurrence and metastasis in RCC patients.     

肾上腺淋巴瘤CT及18F-FDG PET/CT主要特征分析

 目的 探讨肾上腺淋巴瘤的CT及¹⁸F-FDG PET/CT影像学征象,以提高对该病的诊断水平。方法 回顾性分析经手术病理证实10例肾上腺淋巴瘤的临床、影像及病理资料,均行CT平扫及增强扫描及¹⁸F-FDG PET/CT检查,观察和比较肿瘤发生的一般资料(年龄、性别),MSCT表现(部位、最大径、形态、密度、边界、强化方式、腹膜后淋巴结等情况,并计算各期强化率)和计算病灶SUVmax。结果 原发性肾上腺淋巴瘤7例,继发性肾上腺淋巴瘤3例;双侧病灶者7例,单侧病灶者3例,共计17侧病灶;肿瘤最大径不等,平均5.6 cm;肿块呈椭圆形共13侧,三角形3侧,1侧呈结节状增生;13侧边界清晰,4侧边界模糊;病灶平扫CT值平均40.4 Hu;动脉期平均强化率为24.28%;静脉期平均强化率37.46%;大部分(14/17)CT平扫及(13/17)增强密度较均匀一致,动脉期呈轻中度强化,门脉期呈进行性强化;2例发现腹膜后淋巴结肿大。均表现为¹⁸F-FDG高摄取,SUVmax为8.7～23.5,平均值为12.5。结论 肾上腺淋巴瘤CT表现具有一定特征,PET/CT 可准确显示肿瘤累及的范围和淋巴结,在诊断和治疗中具有重要的价值。     

Usefulness of 18F-FDG PET/CT for the Evaluation of Bone Marrow Involvement in Patients with High-Grade Non-Hodgkin’s Lymphoma

Purpose

To assess the usefulness of ¹⁸F-fluorodeoxyglucose PET/CT in the detection of bone marrow (BM) involvement of high-grade non-Hodgkin’s lymphoma (NHL).

Methods

One hundred twenty patients with newly diagnosed diffuse large B-cell lymphoma or peripheral T-cell lymphoma between January 2007 and June 2011, who received BM trephine biopsy and ¹⁸F-FDG PET/CT before chemotherapy, were included in this retrospective study. We reviewed their ¹⁸F-FDG PET/CT images and bone marrow biopsy (BMB) results. After reviewing the images, we reviewed the medical records and radiological findings of interesting patients.

Results

There were 23 ¹⁸F-FDG PET/CT scans in which the marrow was considered to be abnormal (either positive or equivocal), and 97 ¹⁸F-FDG PET/CT scans were regarded as having negative FDG uptake. Of 120 patients, 100 (83.3 %) had a concordant result of BM interpretation between ¹⁸F-FDG PET/CT and BMB, and the remaining 20 patients had discordant results. Among 23 patients with either positive or equivocal ¹⁸F-FDG PET/CT scans, 1 of 12 patients with ‘positive’ ¹⁸F-FDG PET/CT had a lymphomatous involvement on BMB. In contrast, 10 of 11 patients with ‘equivocal’ BM hypermetabolism were reported as having positive involvement by BMB. Patients with abnormal ¹⁸F-FDG PET/CT had significantly higher mSUV_highest than those with normal FDG-PET/CT.

Conclusions

¹⁸F-FDG PET/CT and BMB are complementary techniques in assessing the presence of BM involvement in patients with high-grade NHL. The increasing availability of ¹⁸F-FDG PET/CT will raise the need for additional biopsy for FDG-avid lesions, especially in patients with negative standard BMBs. ¹⁸F-FDG PET/CT can be useful as a decision-making tool for determining whether to perform a standard BMB or targeted biopsy to the FDG-avid lesion as an initial staging procedure. A direct bone biopsy for FDGpositive bone lesions should be included in staging guidelines in future. In ¹⁸F-FDG PET/CT-negative cases, BMB is still a powerful procedure, but BMB alone is insufficient for full evaluation of BM.     

False-Positive FDG PET Uptake−the Role of PET/CT

Positron emission tomography (PET) is a powerful molecular imaging technique for the human body-imaging applications currently available. As altered glucose metabolism is characteristic for many malignancies, FDG-PET is mostly used in oncology for staging and therapy control. Although PET is a sensitive tool for detecting malignancy, FDG uptake is not tumor specific. It can also be seen in healthy tissue or in benign disease as inflammation or posttraumatic repair and could be mistaken for cancer. The experienced nuclear medicine physician mostly manages to differentiate malignant from non-malignant FDG uptake, but some findings may remain ambiguous. In these cases, the difficulties in differentiating physiologic variants or benign causes of FDG uptake from tumor tissue can often be overcome by combined PET and CT (PET/CT) as anatomic information is added to the metabolic data. Thus, PET/CT improves the diagnostic accuracy compared to PET alone and helps to avoid unnecessary surgery/therapy. However, PET/CT involves other sources of artifacts that may occur when using CT for attenuation correction of PET or by patient motion caused by respiration or bowel movements.     

A Case of Meigs’ Syndrome: The 18F-FDG PET/CT Findings

The findings of an ovarian mass with marked ascites and pleural effusion are highly suggestive of malignancy, especially in a postmenopausal female with an elevated level of CA-125. However, benign conditions such as Meigs’ syndrome should be considered in the differential diagnosis if the primary mass shows benign features. ¹⁸F-FDG is known to be useful to differentiate between malignant and benign diseases, and this utility is also promising in the case of ovarian tumor. We present here a case of Meigs’ syndrome that was evaluated by ¹⁸F-FDG PET/CT, and this helped the preoperative diagnosis be made. ¹⁸F-FDG PET/CT is a promising modality to diagnose the pathological character of an ovarian tumor preoperatively, which can lead to a proper therapeutic plan.     

Castleman病18 F-FDG PET/CT显像一例

患者男，67岁，进食后觉中上腹部不适10d入院。无恶心、呕吐、无腹泻，腹部MRI颖胰头癌腹主动脉旁淋巴结转移及肝肾多发囊肿（图1a），否认肝炎，结核及糖尿病等病史。体格检查：体温36.7℃，呼吸18次/min，脉博78次/min,血压121/68mmHg（1mmHg=0.133kPa）,精神面容，营养中等。全身浅表淋巴结未及肿大，腹部未见胃肠型及肠蠕动波，     

18F-FDG PET/CT在前列腺癌中的应用进展

前列腺癌是临床常见的恶性肿瘤之一,在我国的发病率呈逐年上升趋势。18F-FDG是一种广谱的肿瘤非特异性显像剂,在多数肿瘤的临床应用中都具有重要价值。但临床实践表明,18F-FDG PET/CT显像在前列腺癌早期诊断中的价值是有限的。随着认识的深入,人们发现其在前列腺癌临床分期、疗效评价、预后评估等方面仍具有重要价值。笔者将对18F-FDG PET/CT在前列腺癌中的应用进展予以综述。