Imaging proliferation in brain tumors with 18F-FLT PET: comparison with 18F-FDG.

3'-Deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) is a recently developed PET tracer to image tumor cell proliferation. We characterized (18)F-FLT PET of brain gliomas and compared (18)F-FLT with (18)F-FDG PET in side-by-side studies of the same patients. METHODS: Twenty-five patients with newly diagnosed or previously treated glioma underwent PET with (18)F-FLT and (18)F-FDG on consecutive days. Three stable patients in long-term remission were included as negative control subjects. Tracer kinetics in normal brain and tumor were measured. Uptake of (18)F-FLT and (18)F-FDG was quantified by the standardized uptake value (SUV) and the tumor-to-normal tissue (T/N) ratio. The accuracy of (18)F-FLT and (18)F-FDG PET in evaluating newly diagnosed and recurrent gliomas was compared. More than half of the patients underwent resection after the PET study and correlations between PET uptake and the Ki-67 proliferation index were examined. Patients were monitored for a mean of 15.4 mo (range, 12-20 mo). The predictive power of PET for tumor progression and survival was analyzed using Kaplan-Meier statistics. RESULTS: (18)F-FLT uptake in tumors was rapid, peaking at 5-10 min after injection and remaining stable up to 75 min. Hence, a 30-min scan beginning at 5 min after injection was sufficient for imaging. (18)F-FLT visualized all high-grade (grade III or IV) tumors. Grade II tumor did not show appreciable (18)F-FLT uptake and neither did the stable lesions. The absolute uptake of (18)F-FLT was low (maximum-pixel SUV [SUV(max)], 1.33) but image contrast was better than with (18)F-FDG (T/N ratio, 3.85 vs. 1.49). (18)F-FDG PET studies were negative in 5 patients with recurrent high-grade glioma who subsequently suffered tumor progression within 1-3 mo. (18)F-FLT SUV(max) correlated more strongly with Ki-67 index (r = 0.84; P < 0.0001) than (18)F-FDG SUV(max) (r = 0.51; P = 0.07). (18)F-FLT uptake also had more significant predictive power with respect to tumor progression and survival (P = 0.0005 and P = 0.001, respectively). CONCLUSION: Thirty-minute (18)F-FLT PET 5 min after injection was more sensitive than (18)F-FDG to image recurrent high-grade tumors, correlated better with Ki-67 values, and was a more powerful predictor of tumor progression and survival. Thus, (18)F-FLT appears to be a promising tracer as a surrogate marker of proliferation in high-grade gliomas.     

Comparison of 18F-FLT PET and 18F-FDG PET in esophageal cancer.

18F-FDG PET has gained acceptance for staging of esophageal cancer. However, FDG is not tumor specific and false-positive results may occur by accumulation of FDG in benign tissue. The tracer 18F-fluoro-3'-deoxy-3'-L-fluorothymidine (18F-FLT) might not have these drawbacks. The aim of this study was to investigate the feasibility of 18F-FLT PET for the detection and staging of esophageal cancer and to compare 18F-FLT PET with 18F-FDG PET. Furthermore, the correlation between 18F-FLT and 18F-FDG uptake and proliferation of the tumor was investigated. METHODS: Ten patients with biopsy-proven cancer of the esophagus or gastroesophageal junction were staged with CT, endoscopic ultrasonography, and ultrasound of the neck. In addition, all patients underwent a whole-body 18F-FLT PET and 18F-FDG PET. Standardized uptake values were compared with proliferation expressed by Ki-67 positivity. RESULTS: 18F-FDG PET was able to detect all esophageal cancers, whereas 18F-FLT PET visualized the tumor in 8 of 10 patients. Both 18F-FDG PET and 18F-FLT PET detected lymph node metastases in 2 of 8 patients. 18F-FDG PET detected 1 cervical lymph node that was missed on 18F-FLT PET, whereas 18F-FDG PET showed uptake in benign lesions in 2 patients. The uptake of 18F-FDG (median standardized uptake value [SUV(mean)], 6.0) was significantly higher than 18F-FLT (median SUV(mean), 3.4). Neither 18F-FDG maximum SUV (SUV(max)) nor 18F-FLT SUV(max) correlated with Ki-67 expression in the linear regression analysis. CONCLUSION: In this study, uptake of 18F-FDG in esophageal cancer is significantly higher compared with 18F-FLT uptake. 18F-FLT scans show more false-negative findings and fewer false-positive findings than do 18F-FDG scans. Uptake of 18F-FDG or 18F-FLT did not correlate with proliferation.     

Imaging proliferation in lung tumors with PET: 18F-FLT versus 18F-FDG.

Recently, the thymidine analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) was suggested for imaging tumoral proliferation. In this prospective study, we examined whether (18)F-FLT better determines proliferative activity in newly diagnosed lung nodules than does (18)F-FDG. METHODS: Twenty-six patients with pulmonary nodules on chest CT were examined with PET and the tracers (18)F-FDG and (18)F-FLT. Tumoral uptake was determined by calculation of standardized uptake value (SUV). Within 2 wk, patients underwent resective surgery or had core biopsy. Proliferative activity was estimated by counting nuclei stained with the Ki-67-specific monoclonal antibody MIB-1 per total number of nuclei in representative tissue specimens. The correlation between the percentage of proliferating cells and the SUVs for (18)F-FLT and (18)F-FDG was determined using linear regression analysis. RESULTS: Eighteen patients had malignant tumors (13 with non-small cell lung cancer [NSCLC], 1 with small cell lung cancer, and 4 with pulmonary metastases from extrapulmonary tumors); 8 had benign lesions. In all visible lesions, mean (18)F-FDG uptake was 4.1 (median, 4.4; SD, 3.0; range, 1.0-10.6), and mean (18)F-FLT uptake was 1.8 (median, 1.2; SD, 2.0; range, 0.8-6.4). Statistical analysis revealed a significantly higher uptake of (18)F-FDG than of (18)F-FLT (Mann-Whitney U test, P < 0.05). (18)F-FLT SUV correlated better with proliferation index (P < 0.0001; r = 0.92) than did (18)F-FDG SUV (P < 0.001; r = 0.59). With the exception of 1 carcinoma in situ, all malignant tumors showed increased (18)F-FDG PET uptake. (18)F-FLT PET was false-negative in the carcinoma in situ, in another NSCLC with a low proliferation index, and in a patient with lung metastases from colorectal cancer. Increased (18)F-FLT uptake was related exclusively to malignant tumors. By contrast, (18)F-FDG PET was false-positive in 4 of 8 patients with benign lesions. CONCLUSION: (18)F-FLT uptake correlates better with proliferation of lung tumors than does uptake of (18)F-FDG and might be more useful as a selective biomarker for tumor proliferation.     

Imaging gastric cancer with PET and the radiotracers 18F-FLT and 18F-FDG: a comparative analysis.

In this pilot study, we evaluated 3'-deoxy-3'-(18)F-fluorothymidine (FLT) PET for the detection of gastric cancer and compared the diagnostic accuracy with that of (18)F-FDG PET. METHODS: Forty-five patients (31 male and 14 female) with histologically proven locally advanced gastric cancer underwent attenuation-corrected whole-body (18)F-FLT PET and (18)F-FDG PET/CT (low-dose CT). (18)F-FLT emission images were acquired on a full-ring PET scanner 45 min after the injection of 270-340 MBq of (18)F-FLT. (18)F-FDG PET/CT was performed 60 min after the injection of 300-370 MBq of (18)F-FDG. Mean standardized uptake values for (18)F-FLT and (18)F-FDG were calculated using circular ROIs (diameter, 1.5 cm) in the primary tumor manifestation site, in a reference segment of the liver, and in the bone marrow and were compared on a lesion-by-lesion basis. RESULTS: According to the Lauren classification, 15 tumors (33%) were of the intestinal subtype and 30 (67%) of the nonintestinal subtype. (18)F-FLT PET images showed high contrast for the primary tumor and proliferating bone marrow. In all patients (45/45), focal (18)F-FLT uptake could be detected in the primary tumor. In contrast, 14 primary tumors were negative for (18)F-FDG uptake, with lesional (18)F-FDG uptake lower than or similar to background activity. The mean standardized uptake value for (18)F-FLT in malignant primaries was 6.0 +/- 2.5 (range, 2.4-12.7). In the subgroup of (18)F-FDG-positive patients, the mean value for (18)F-FDG was 8.4 +/- 4.1 (range, 3.8/19.0), versus 6.8 +/- 2.6 for (18)F-FLT (Wilcoxon test: P = 0.03). Comparison of mean (18)F-FLT and (18)F-FDG uptake in tumors with signet ring cells revealed no statistically significant difference between the tracers (6.2 +/- 2.1 for (18)F-FLT vs. 6.4 +/- 2.8 for (18)F-FDG; Wilcoxon test: P = 0.94). CONCLUSION: The results of this study indicate that imaging gastric cancer with the proliferation marker (18)F-FLT is feasible. (18)F-FLT PET was more sensitive than (18)F-FDG PET, especially in tumors frequently presenting without or with low (18)F-FDG uptake, and may improve early evaluation of response to neoadjuvant treatment.     

Imaging of proliferation with 18F-FLT PET/CT versus 18F-FDG PET/CT in non-small-cell lung cancer

Purpose  

To compare the diagnostic efficacies of ¹⁸F-FLT and ¹⁸F-FDG PET/CT in non-small-cell lung cancer (NSCLC), focusing on the correlation between FLT and FDG tumour uptake and tumour cell proliferation as indicated by the cyclin D1 labelling index.     

肺癌18F-FLT PET和18F-FDG PET的临床对比研究

目的 探讨18F-FLT PET在肺癌诊断和肿瘤增殖检测方面的应用价值.方法 对2005年9月-2008年10月解放军总医院收治的36例(男27例,女9例,年龄38～74岁)胸部CT疑似肺癌患者进行18F-FLT PET扫描,对同期收治的42例(男29例,女13例,年龄37～75岁)胸部CT疑似肺癌患者进行18F-FD...     

18F-FDG和18F-FLT PET/CT在肺部良恶性肿瘤鉴别诊断中的价值

目的:分析18F-FDG(18F-脱氧葡萄糖)和18F-FLT(18F-胸腺嘧啶)两种显像剂的PET/CT检查在肺部肿瘤中的不同影像学表现,提高PET/CT在肺部良恶性肿瘤鉴别诊断中价值,从而为临床治疗方案的选择提供可靠依据。方法:收集肺肿瘤患者55例为研究对象,其中男性33例,女性22例,年龄17～82岁,28例为肺内孤立肿块,其余为2～3个肿块,肿块大小0.6～11.0cm,所有患者均行肺部18 F-FDG和18 F-FLT PET/CT检查,分析18 F-FDG和18 F-FLT标准摄取值(SUV)与肺肿瘤患者的年龄、肿块大小及病理类型等相互关系和统计学意义。结果:18 F-FDG和18 F-FLT PET/CT的SUV与肺肿瘤患者的年龄、肿块大小均无统计学差异(P>0.05),18 F-FDG PET/CT的SUV与患者的病理类型亦无统计学差异(P>0.05),而18F-FLT PET/CT的SUV与患者的病理类型有统计学差异(P<0.05)。结论:肺肿瘤患者的肿块病理类型是影响18F-FLT PET/CT的SUV的重要因素,18F-FLT PET/CT的SUV在肺部良恶性肿瘤鉴别诊断中具有重要的价值。     

18F-FDG和18F-FLT PET对肿瘤放化疗疗效评价的实验研究

PET可从分子水平观察细胞生物学行为。目前,临床上最常用的葡萄糖代谢显像剂是18F-FDG,而最常用的细胞增殖显像剂是3’-脱氧-3’-18F-氟胸腺嘧啶(18F-FLT)。这两种显像剂在肿瘤的诊断和分期方面已有深入广泛的研究,而在治疗后疗效评价方面的研究近年也很受重视,特别是肿瘤在放化疗前后对18F-FDG和18F-...     

Detection of gastric cancer using <Superscript>18</Superscript>F-FLT PET: comparison with <Superscript>18</Superscript>F-FDG PET

Purpose  We prospectively investigated the feasibility of 3′-deoxy-3′-¹⁸F-fluorothymidine (FLT) positron emission tomography (PET) for the detection of gastric cancer, in comparison with 2-deoxy-2-¹⁸F-fluoro-d-glucose (FDG) PET, and determined the degree of correlation between the two radiotracers and proliferative activity as indicated by Ki-67 index. Methods  A total of 21 patients with newly diagnosed advanced gastric cancer were examined with FLT PET and FDG PET. Tumour lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated. Results  For detection of advanced gastric cancer, the sensitivities of FLT PET and FDG PET were 95.2% and 95.0%, respectively. The mean (±SD) SUV for FLT (7.0 ± 3.3) was significantly lower than that for FDG (9.4 ± 6.3 p < 0.05). The mean FLT SUV and FDG SUV in nonintestinal tumours were higher than in intestinal tumours, although the difference was not statistically significant. The mean (±SD) FLT SUV in poorly differentiated tumours (8.5 ± 3.5) was significantly higher than that in well and moderately differentiated tumours (5.3 ± 2.1; p < 0.04). The mean FDG SUV in poorly differentiated tumours was higher than in well and moderately differentiated tumours, although the difference was not statistically significant. There was no significant correlation between Ki-67 index and either FLT SUV or FDG SUV. Conclusion  FLT PET showed as high a sensitivity as FDG PET for the detection of gastric cancer, although uptake of FLT in gastric cancer was significantly lower than that of FDG.     

~(18)F-FDG和~(18)F-FLT PET显像SUV在肺结块诊断中的价值

目的:探讨18F-氟氏脱氧葡萄糖(18F-FDG)和18F-氟氏胸腺嘧啶(18F-FLT)PET显像诊断肺结块的影响因素,以提高PET/CT对肺结块的诊断价值。方法:选择肺结块患者55例为研究对象,其中28例为肺内孤立结块,其余为2～3个结块,结块大小0.6～11.0cm。所有患者均行肺部18 F-FDG和18 F-FLT PET/CT检查,检查结果按不同性别、年龄、结块大小及病理类型进行分组,以各组18F-FDG和18F-FLT显像标准摄取值(SUV)的均数为界定标准,分析SUV与肺结块患者的性别、年龄、结块大小及病理类型等相互关系。结果:55例肺结块患者,不同性别、年龄、结块大小患者的18 F-FDG和18F-FLT显像SUV差异均无统计学意义(P>0.05),不同病理类型患者的18 F-FDG显像SUV差异无统计学意义(P>0.05),而不同病理类型患者的18F-FLT显像SUV差异有统计学意义(P<0.05)。结论:肺结块患者结块的病理类型是影响18F-FLT显像SUV的重要因素,18F-FLT PET/CT显像SUV鉴别诊断肺结块良恶性具有重要的价值和意义。     

18F-FDG和18F-FLT PET/CT不同诊断方法在肺部单发结节中的临床价值分析

目的：探讨18F-FDG和18F-胸腺嘧啶核苷（FLT）PET/CT不同的诊断方法对肺部单发结节的诊断价值。方法对40例发现肺部单发结节的患者行18F-FDG和18F-FLT PET/CT显像,所有病例均经病理或密切随访确诊,应用受试者工作特征（ROC）曲线比较18F-FDG SUVmax、18F-FLT SUVmax、18F-FLT SUVmax/同层面椎体SUVmax对肺部恶性肿瘤的诊断价值;18F-FDG和18F-FLT PET/CT两种显像结果均行视觉分析和半定量分析,比较不同诊断方法的诊断效能。结果18F-FDG SUVmax、18F-FLT SUVmax及18F-FLT SUVmax/同层面椎体SUVmaxROC曲线下面积分别为0.687、0.821和0.817。以18F-FDG SUVmax>2.5、18F-FLT SUVmax>2.0为恶性诊断标准、18F-FDG PET/CT视觉分析评分法、18F-FLT PET/CT视觉分析评分法4种方法诊断肺癌的灵敏度、特异度和准确率分别为88.2%、73.9%和80.0%;58.8%、82.6%和72.5%;94.1%、91.3%和92.5%;88.2%、65.2%和75.0%。结论18F-FLT SUVmax及18F-FLT SUVmax/同层面椎体SUVmax单独诊断肺部恶性肿瘤的价值较18F-FDG SUVmax高,且前两者可替换使用。18F-FDG PET/CT视觉评分法在肺部单发结节良恶性的诊断中效能最佳。     

The value of SUV in 18F-FDG and 18F-FLT PET imaging for diagnosing pulmonary nodules

目的:探讨18F-氟氏脱氧葡萄糖(18F-FDG)和18F-氟氏胸腺嘧啶(18F-FLT)PET显像诊断肺结块的影响因素,以提高PET/CT对肺结块的诊断价值.方法:选择肺结块患者55例为研究对象,其中28例为肺内孤立结块,其余为2～3个结块,结块大小0.6～11.0 cm.所有患者均行肺部18F-FDG和18F-FLT PET/CT检查.检查结果按不同性别、年龄、结块大小及病理类型进行分组,以各组18F-FDG和18F-FLT显像标准摄取值(SUV)的均数为界定标准.分析SUV与肺结块患者的性别、年龄、结块大小及病理类型等相互关系.结果:55例肺结块患者,不同性别、年龄、结块大小患者的18F-FDG和18F-FLT显像SUV差异均无统计学意义(P>0.05),不同病理类型患者的18F-FDG显像SUV差异无统计学意义(P>0.05),而不同病理类型患者的18F-FLT显像SUV差异有统计学意义(P<0.05).结论:肺结块患者结块的病理类型是影响18F-FLT显像SUV的重要因素,18F-FLT PET/CT显像SUV鉴别诊断肺结块良恶性具有重要的价值和意义.     

18F-FDG符合线路显像检测甲状腺癌转移灶的价值

目的　比较18F 脱氧葡萄糖 (FDG)双探头符合线路SPECT(DHCI)与PET显像检测甲状腺癌转移病灶的价值。方法　 2 6例甲状腺癌患者在同 1天分别进行了18F FDGPET和18F FDGDHCI显像 ,患者均已行甲状腺切除术和131I治疗。肿瘤转移病灶大小由计算机自动勾边在PET显像图中测定。结果　 2 6例甲状腺癌患者中 ,18F FDGPET共发现 12 6个肿瘤转移病灶 ,其中18F FDGDHCI检测到 92个 (73 % ) ,CT发现 76个 (6 0 % ) ,18F FDGDHCI的病灶检测率明显高于CT(P <0 0 5 )。根据病灶部位分析 ,18F FDGDHCI与PET对转移病灶检测的符合率在头颈部为 6 8% ,胸部为 83% ,而在骨转移病灶的符合率仅为 5 2 % (P <0 0 1)。根据病灶大小分析 ,当肿瘤转移病灶大于 1 5cm时 ,18F FDGDHCI与PET结果的一致率达 98% ;而在 1～ 1 5cm的病灶检测中 ,18F FDGDHCI仅能发现 5 6 % ;当病灶小于 1cm时 ,18F FDGDHCI则难以发现 ,而PET发现的病灶最小直径为 0 7cm。结论　当肿瘤转移病灶的直径大于 1 5cm时 ,18F FDGDHCI与PET具有相似的诊断准确性。     

^18F-FLT和^18F-FDG PET显像早期评估荷肺腺癌小鼠放疗疗效

目的:比较18F-FLT和18F-FDG早期评估荷肺腺癌小鼠放疗疗效.材料和方法:24只T739荷肺腺癌小鼠随机分为18F-FLT和18F-FDG两组,各组再分为对照组和放疗组.放疗组接受20Gy的X线放射治疗后2天,各组小鼠经尾静脉注入18F-FLT和18F-FDG60min后行PET显像并井形探测仪测量活性分布.肿瘤增殖判定采用免疫组织化学方法测定PCNA.结果:放疗后肿瘤18F-FLT摄取较对照组明显降低(0.37±0.12%和1.25±0.19%,P<0.01),而18F-FDG摄取变化不明显.PET显像18F-FLTSUVmax值低于对照组,18F-FDG摄取变化不明显.肿瘤18F-FLT摄取与PCNA指数显著相关(r=0.8805),18F-FDG摄取与PCNA无相关性.结论:放疗后18F-FLT摄取降低较18F-FDG明显,与PCNA指数显著相关,因而18F-FLT是一种监测肿瘤治疗疗效的有前途的示踪剂.     

18F-FLT和18F-FDG PET/CT对胸段食管癌淋巴结分期诊断的对比研究

目的 评价18F-脱氧胸苷（FLT）PET/CT对未经治疗的胸段食管癌淋巴结分期诊断的价值,并与18F-脱氧葡萄糖（FDG）PET/CT进行比较.方法 选择22例拟行手术治疗的胸段食管癌患者,术前行双显像剂PET/CT检查及淋巴结分期诊断,术后以病理学诊断为＂金标准＂,比较18F-FLT和18F-FDG PET/CT对胸段食管癌淋巴结分期的灵敏度、特异性、准确性、阳性预测值和阴性预测值.应用SPSS 13.0软件进行x2检验.结果 患者均行食管癌切除和淋巴结清扫术,病理检查结果显示16例患者存在淋巴结转移,N0期7例,N1期15例,M1a期6例（其中1例为N0M1a,另外5例为N1M1a）,全组均无M1b期.共检出424枚淋巴结,其中47枚为转移淋巴结.18F-FDG PET/CT诊断呈假阳性的淋巴结14枚,而18F-FLT诊断呈假阳性的淋巴结为3枚;18F-FDG假阴性的淋巴结8枚,18F-FLT假阴性的淋巴结12枚.18F-FLT PET/CT的诊断灵敏度、特异性、准确性、阴性预测值和阳性预测值分别为74.47%（35/47）、99.20%（374/377）、96.46%（409/424）、96.89%（374/386）和92.11%（35/38）,18F-FDG分别为82.98%（39/47）、96.29%（363/377）、94.81%（402/424）、97.84%（363/371）和73.58%（39/53）;两者比较的x2值分别为0.572,6.018,1.017,0.348,3.852,P值分别＞0.05,＜0.05、＞0.05、＞0.05和＞0.05.结论 18F-FLT对食管癌区域淋巴结的诊断灵敏度与18F-FDG显像接近,特异性高于18F-FDG,但仍存在一定的局限性.     

Evaluation of head and neck cancer with 18F-FDG PET: a comparison with conventional methods

The aim of this study was to evaluate the usefulness of ¹⁸F-FDG PET in the diagnosis and staging of primary and recurrent malignant head and neck tumours in comparison with conventional imaging methods [including ultrasonography, radiography, computed tomography (CT) and magnetic resonance imaging (MRI)], physical examination, panendoscopy and biopsies in clinical routine. A total of 54 patients (13 female, 41 male, age 61.3ᆠ years) were investigated retrospectively. Three groups were formed. In group I, ¹⁸F-FDG PET was performed in 15 patients to detect unknown primary cancers. In group II, 24 studies were obtained for preoperative staging of proven head and neck cancer. In group III, ¹⁸F-FDG PET was used in 15 patients to monitor tumour recurrence after radiotherapy and/or chemotherapy. In all patients, imaging was obtained at 70 min after the intravenous administration of 180 MBq ¹⁸F-FDG. In 11 of the 15 patients in group I, the primary cancer could be found with ¹⁸F-FDG, yielding a detection rate of 73.3%. In 4 of the 15 patients, CT findings were also suggestive of the primary cancer but were nonetheless equivocal. In these patients, ¹⁸F-FDG showed increased ¹⁸F-FDG uptake by the primary tumour, which was confirmed by histology. One patient had recurrence of breast carcinoma that could not be detected with ¹⁸F-FDG PET, but was detected by CT. In three cases, the primary cancer could not be found with any imaging method. Among the 24 patients in group II investigated for staging purposes, ¹⁸F-FDG PET detected a total of 13 local and three distant lymph node metastases, whereas the conventional imaging methods detected only nine local and one distant lymph node metastases. The results of ¹⁸F-FDG PET led to an upstaging in 5/24 (20.8%) patients. The conventional imaging methods were false positive in 5/24 (20.8%). There was one false positive result using ¹⁸F-FDG PET. Among the 15 patients of group III with suspected recurrence after radiotherapy and/or chemotherapy, ¹⁸F-FDG was true positive in 7/15 (46.6%) and true negative in 4/15 (26.6%). The conventional imaging methods were true positive in 5/15 (33.3%) and true negative in 4/15 (26.6%). One false negative (6.6%) and three false positive findings (20%) on ¹⁸F-FDG PET were due to inflamed tissue. The conventional imaging methods were false positive in three (20%) and false negative in three cases (20%). It is concluded that in comparison to conventional diagnostic methods, ¹⁸F-FDG PET provides additional and clinically relevant information in the detection of primary and metastatic carcinomas as well as in the early detection of recurrent or persistent head and neck cancer after radiotherapy and/or chemotherapy. ¹⁸F-FDG PET should therefore be performed early in clinical routine, usually before CT or MRI.     

Evaluation of head and neck cancer with 18F-FDG PET: a comparison with conventional methods

The aim of this study was to evaluate the usefulness of 18F-FDG PET in the diagnosis and staging of primary and recurrent malignant head and neck tumours in comparison with conventional imaging methods [including ultrasonography, radiography, computed tomography (CT) and magnetic resonance imaging (MRI)], physical examination, panendoscopy and biopsies in clinical routine. A total of 54 patients (13 female, 41 male, age 61.3+/-12 years) were investigated retrospectively. Three groups were formed. In group I, 18F-FDG PET was performed in 15 patients to detect unknown primary cancers. In group II, 24 studies were obtained for preoperative staging of proven head and neck cancer. In group III, 18F-FDG PET was used in 15 patients to monitor tumour recurrence after radiotherapy and/or chemotherapy. In all patients, imaging was obtained at 70 min after the intravenous administration of 180 MBq 18F-FDG. In 11 of the 15 patients in group I, the primary cancer could be found with 18F-FDG, yielding a detection rate of 73.3%. In 4 of the 15 patients, CT findings were also suggestive of the primary cancer but were nonetheless equivocal. In these patients, 18F-FDG showed increased 18F-FDG uptake by the primary tumour, which was confirmed by histology. One patient had recurrence of breast carcinoma that could not be detected with 18F-FDG PET, but was detected by CT. In three cases, the primary cancer could not be found with any imaging method. Among the 24 patients in group II investigated for staging purposes, 18F-FDG PET detected a total of 13 local and three distant lymph node metastases, whereas the conventional imaging methods detected only nine local and one distant lymph node metastases. The results of 18F-FDG PET led to an upstaging in 5/24 (20.8%) patients. The conventional imaging methods were false positive in 5/24 (20.8%). There was one false positive result using 18F-FDG PET. Among the 15 patients of group III with suspected recurrence after radiotherapy and/or chemotherapy, 18F-FDG was true positive in 7/15 (46.6%) and true negative in 4/15 (26.6%). The conventional imaging methods were true positive in 5/15 (33.3%) and true negative in 4/15 (26.6%). One false negative (6.6%) and three false positive findings (20%) on 18F-FDG PET were due to inflamed tissue. The conventional imaging methods were false positive in three (20%) and false negative in three cases (20%). It is concluded that in comparison to conventional diagnostic methods, 18F-FDG PET provides additional and clinically relevant information in the detection of primary and metastatic carcinomas as well as in the early detection of recurrent or persistent head and neck cancer after radiotherapy and/or chemotherapy. 18F-FDG PET should therefore be performed early in clinical routine, usually before CT or MRI.     

Detection of hepatocellular carcinoma using 11C-choline PET: comparison with 18F-FDG PET

The purpose of this study was to retrospectively investigate the feasibility of 11C-choline PET, compared with 18F-FDG PET, for the detection of hepatocellular carcinoma (HCC). METHODS: A total of 16 HCC lesions in 12 patients were examined with both 11C-choline PET and 18F-FDG PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding noncancerous liver tissue. For semiquantitative analysis, the tumor-to-liver (T/L) ratio was calculated by dividing the maximal standardized uptake value (SUV) in HCC lesions by the mean SUV in noncancerous liver tissue. RESULTS: 11C-choline PET showed a slightly higher detection rate than did 18F-FDG PET for detection of HCC (63% vs. 50%, respectively), although this difference was not statistically significant. 11C-choline PET had a better detection rate for moderately differentiated HCC lesions but not for those poorly differentiated (75% vs. 25%, respectively). In contrast, 18F-FDG PET exhibited the opposite behavior, with corresponding detection rates of 42% and 75%, respectively. The mean 11C-choline SUV and T/L ratio in moderately differentiated HCC lesions were higher than those in poorly differentiated HCC lesions. In contrast, the mean 18F-FDG SUV and T/L ratio in poorly differentiated HCC were higher than those in moderately differentiated HCC. These differences, however, were also not statistically significant. CONCLUSION: 11C-choline PET had a better detection rate for moderately differentiated HCC lesions but not for poorly differentiated HCC lesions, whereas 18F-FDG PET produced the opposite result. 11C-choline is a potential tracer to complement 18F-FDG in detection of HCC lesions.