18F-FDG PET显像在头颈部肿瘤中的应用

目的 探讨^18F-脱氧葡萄糖（FDG）PET显像在头颈部肿瘤中的应用.方法 39例头颈部肿瘤患者,共行56次^18F-FDG PET检查.图像分析采用视觉和半定量（标准摄取值,SUV）方法.结果 ①5例治疗前患者,PET显像使3例改变了分期;34例治疗后患者中,PET显像发现6例头颈部有残存或复发灶,11例淋巴结转移,4例肺部转移,3例骨转移.②22例PET显像阳性患者中,20例经手术病理检查或随访证实,2例假阳性;17例PET显像为阴性的患者均得到随访证实.PET显像用于头颈部肿瘤病情监测的灵敏度为100%,特异性为89.5%,准确性为94.9%.③21例患者有近期CT或MRI检查结果,其中6例PET显像发现了CT或MRI未发现的局部复发病灶和转移淋巴结.6例患者CT或MRI提示有肿瘤复发或转移,但PET显像结果阴性,并经随访证实.④9例患者多次进行PET检查随访,其中5例病灶消失,3例病情进展,1例无变化.结论 ^18F-FDG PET显像可较准确地发现头颈部肿瘤的残存、转移和复发病灶,并为肿瘤分期提供重要依据,但应与炎症鉴别.     

18F-FDG PET显像对胰腺良恶性病变鉴别诊断的作用

目的探讨18F-脱氧葡萄糖(FDG) PET显像对胰腺良恶性病变鉴别诊断的价值.方法临床疑胰腺病变患者30例,其中胰腺恶性肿瘤20例胰腺癌15例,胰腺癌切除术后复发3例,低恶性胰岛细胞瘤、癌肉瘤各1例;胰腺良性病变10例,均为慢性胰腺炎,其中3例并假性囊肿形成.除8例慢性胰腺炎为临床、放射学随访3～12个月外,余均由组织病理学检查证实.静脉注射18F-FDG 222～296 MBq 1 h后行PET显像.测定肿瘤体积和标准摄取值(SUV),并与PET检查前2周内CT(25例)、MRI(8例)结果对照.结果 20例胰腺恶性肿瘤中19例肿瘤明显摄取18F-FDG,平均SUV 4.91±3.65.10例慢性胰腺炎中9例病灶轻度或无摄取18F-FDG,平均SUV 1.70±1.12(t=2.69,P=0.012).4例肿瘤病灶直径≤3 cm,SUV 2.75±0.63;6例3.1～5 cm,SUV 4.59±3.06;10例>5 cm,SUV 5.46±2.29(χ2=9.02,P=0.011).1例PET假阳性为慢性胰腺炎并假性囊肿,SUV 4.82;1例PET假阴性为胰头癌术后复发,病灶SUV 2.1.以SUV 2.5为胰腺良恶性病变的判断阈值,18F-FDG PET显像诊断胰腺癌灵敏度、特异性和准确性分别为95.0%、90.0%、93.3%,明显高于CT(75.0%、55.6%、68.0%,χ2=5.89,P=0.015).结论 18F-FDG PET显像诊断胰腺癌灵敏度、特异性较高,尤其适于胰腺癌术前分期和术后复发、转移的探查.     

18-FDG PET/CT在肝癌治疗后AFP升高患者中的应用

目的 探讨18F-脱氧葡萄糖(FDG)PET/CT检测肝癌治疗后甲胎蛋白(AFP)升高患者肿瘤复发和(或)转移病灶的价值.方法 原发性肝细胞癌治疗后血清AFP升高患者123例,皆行全身18F-FDG PET/CT显像.所有图像经图像融合后,进行PET/CT融合图像、PET图像和CT图像帧对帧对比分析.肿瘤复发和(或)转移病灶根据病理检查结果、多种影像学诊断及临床随访而确诊.随访时间均>6个月.采用SPSS 11.5软件进行统计学处理,进行X2检验.结果 123例患者中,明确诊断肿瘤复发和(或)转移者111例.18F-FDG PET显像诊断肿瘤复发和(或)转移78例,其灵敏度为70.3%(78/111);18F.FDG PET/CT显像诊断肿瘤复发和(或)转移97例,灵敏度提高至87.4%(97/111,χ2=9.744,P=0.002).18F.FDG PET/CT诊断肝癌复发和转移的特异性、准确性、阳性预测值和阴性预测值分别为83.3%(10/12)、87.0%(107/123)、98.0%(97/99)和41.7%(10/24).9例高分化肝细胞癌患者均确诊为肿瘤复发和(或)转移,18F-FDG PET/CT显像诊断其肿瘤复发和(或)转移5例,灵敏度(5/9)明显低于总体灵敏度(87.4%;χ2=6.616,P=0.01).结论 18F-FDG PET/CT显像在检测原发性肝癌治疗后AFP升高患者肿瘤复发和(或)转移病灶中有较好的应用价值,但高分化肝细胞癌可能出现假阴性.     

~(18)F-氟脱氧葡萄糖PET/CT用于触诊表现阴性的头颈部鳞状细胞癌的前瞻性研究

正摘要目的评价18F-氟脱氧葡萄糖(FDG)正电子发射体层成像(PET)/CT与CT/MRI在触诊表现阴性的头颈部鳞状细胞癌病人的颈部隐匿性转移中的诊断应用。方法此项前     

^18FDG-PET和^99mTc-MDP骨扫描检测骨转移瘤价值的比较

目的:评价18FDG-PET恶性肿瘤骨转移的作用及与99mTc-MDP-ECT 比较.材料和方法: 经病理证实为恶性肿瘤患者51 例及非肿瘤性疾病5例在本科同时接受18F-FDG-PET和99mTc-MDP-ECT检查(时间间隔不超过2周).骨转移的诊断由病理、X线或CT/MRI、随访超过1年综合决定.结果:99mTc-MDP和18FDG-PET 对骨转移瘤诊断的灵敏度、特异性、准确率率分别为93.7%、93.7%,97.5%、50%,90.8%、62.5%.99mTc-MDP和18FDG-PET均为阳性15例,其中证实骨转移为14例,假阳性1例;均为阴性例数为20例.21例不相符的结果中20例99mTc-MDP-ECT 阳性而18F-FDG-PET 为阴性.18F-FDG-PET和99mTc-MDP-ECT假阴性各1例.均诊断为多发骨转移的12例患者中99mTc-MDP-ECT发现的骨转移病灶数多于18F-FDG-PET.结论:18F-FDG-PET 与99mTc-MDP骨扫描相比较对肿瘤骨转移的探测有较高的特异性,但敏感性较低.     

恶性肿瘤术后复发18F-FDG-PET评价

 目的 评价18F-FDG-PET(氟代脱氧葡萄糖正电子发射断层扫描)对恶性肿瘤术后复发的探测能力。方法 10例恶性肿瘤术后患者均经18F-FDG-PET成像,分析所得图像。(1)目视法：将所得结果定为阳性、阴性;(2)半定量方法：选定ROI(感兴趣区)进行SUV(标准摄取值)测定,以SUV＞2.5为阳性;(3)复习同期(2周内)CT／MRI资料。所有结果均与手术病理及临床随访(5～6月)结果对照。结果10例患者中,FDG-PET准确探测4／4例恶性肿瘤术后复发,5／6例阴性,假阳性1例。敏感性、特异性和准确性分别为100％,83.3％和90％。5／10例患者改变了治疗方案。而临床表现评估中其敏感性、特异性和准确性分别为75％,83.3％和80％,CT／MRI评估中其敏感性、特异性和准确性分别为25％,50％和40％。结论 FDG-PET对恶性肿瘤术后复发具有很好的探测能力。     

FDG-PET/增强CT作为头颈部鳞状细胞癌治疗后评估工具:FDG-PET/平扫及增强CT比较

正摘要目的评估静脉注射18F-脱氧葡萄糖(FDG)增强PET/CT对怀疑复发头颈部鳞状细胞癌(HNSCC)的准确性。材料与方法 170例治疗过的HNSCC病人行PET/CT,包括平扫和增强CT,以诊断可能的复发。PET/增强CT(PET/ce CT),PET/平扫CT(PET/nc CT)和ce CT对原位、局部复发、远处转移、总复发和第2原发癌进行评价。参考标准包括组织病理     

18F-FDGSPECT/CT显像在鼻咽癌治疗后EBV-DNA升高患者中的应用

目的:探讨18F-FDG SPECT/CT显像在检测鼻咽癌治疗后血清EBV-DNA升高患者,肿瘤复发和(或)转移病灶的价值.方法:鼻咽癌治疗后血清EBV-DNA升高患者45例,皆行全身18F-FDG SPECT/CT显像.所有图像经图像融合后,进行18F-FDG显像图像和CT图像帧对帧对比分析.肿瘤复发和(或)转移病灶根据病理检查结果、多种影像学诊断及临床随访而确诊.随访时间均＞6个月.采用SPSS 11.5软件进行统计学处理,进行x2检验.结果:45例患者中,明确诊断肿瘤复发和(或)转移者35例,单纯CT诊断肿瘤复发和(或)转移28例,其灵敏度为80.0％ (28/35);符合线路18F-FDG CT同机融合显像诊断肿瘤复发和(或)转移32例,灵敏度提高至91.4％ (32/35).结论:18F-FDG SPECT/CT在检测鼻咽癌治疗后EBV-DNA升高患者肿瘤复发和(或)转移病灶中有较好的应用价值.但角化型鼻咽癌可能出现假阴性.     

CT与MRI对鼻咽癌放疗后局部复发或残留的诊断

目的 探讨CT与MRI对鼻咽癌放疗后局部复发或残留的诊断价值。方法 收集125例放疗后4月～2年CT和/或MRI检查出现异常块影的鼻咽癌患者。73例行鼻咽部活检,活检阴性及未活检患者继续行CT或MRI随访。将CT、MRI结果与病理对比。结果 病理活检或CT、MRI随访复查证实55例(55/125,44.4％)为放疗后局部复发或残留,70例(70/125,55.6％)为放疗后改变。CT诊断鼻咽癌放疗后局部复发或残留的敏感性、特异性、准确性分别为54.8％、73.8％、65.8％;MRI诊断的敏感性、特异性、准确性分别为61.8％、83.7％、74.0％。结论 CT和MRI诊断鼻咽癌放疗后局部复发或残留的准确性相对均较低,MRI稍优于CT。     

18F氟代脱氧葡萄糖PET-CT在头颈部肿瘤中的应用价值

PET-CT能对恶性肿瘤病灶进行准确定位,在头颈部肿瘤的诊断、定位及指导临床治疗方面与单纯PET相比具有明显的优势.PET和CT优势互补,有助于进一步提高诊断及分期的准确性和可信度,有助于鉴别正常生理性摄取、炎症和恶性肿瘤,同时可以更好地指导临床精确放疗.18F-氟代脱氧葡萄糖(18F-FDG)PET-CT在大多数头颈部恶性肿瘤的诊断方面虽然有明显的优越性,但在甲状腺和腮腺病灶的良恶性鉴别、急性炎症与肿瘤的鉴别等方面仍有不足.     

Evaluation of recurrent squamous cell carcinoma of the head and neck with FDG positron emission tomography

PURPOSE: This study compared the effectiveness of fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT), magnetic resonance imaging (MRI), or both for the assessment of recurrent squamous cell carcinoma of the head and neck. The value of quantifying the standardized uptake values (SUV) to distinguish recurrent neoplasm from inflammatory lesions and normal structures was also evaluated. METHODS: Forty-three patients with head and neck cancer were examined with F-18 FDG PET at least 4 months after their last course of radiation therapy (mean, 11 months). The SUVs were measured in visually identified regions of abnormally increased activity and were compared with the values in normal mucosa, the base of the tongue, and the hard palate to determine if an optimal cutoff value exists for diagnosing recurrence of malignant lesions. The final diagnosis of recurrence was made based on biopsy or at least 6 months' clinical follow-up. RESULTS: FDG PET correctly detected recurrence in 20 of 22 patients who had 45 discrete lesions located in the field of the upper aerodigestive tract. Two false-negative and three false-positive results were identified. The accuracy of FDG PET was 88% (38 of 43 patients), compared with 66% (25 of 38 patients) for CT, MRI, or both. Although there was a significant difference of SUVs (P = 0.0036) between the recurrent lesions and normal structures, the optimal cutoff values were difficult to define. CONCLUSIONS: Visual analysis of FDG PET is significantly more accurate in the diagnosis of recurrent squamous cell cancer of the head and neck than are CT or MRI. However, single SUV quantification does not significantly enhance efficacy.     

Diagnostic accuracy of FDG PET imaging for the detection of recurrent or metastatic gynecologic cancer

PURPOSE: This study evaluated the diagnostic role and accuracy of positron emission tomography (PET) using 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) for the detection of tumor foci in patients with suspected recurrent or metastatic lesions of gynecologic cancers. MATERIALS AND METHODS: FDG PET imaging was performed on 51 patients with a previous history of gynecologic cancer who were referred for a clinical suspicion of recurrent disease. PET acquisition was started 50-60 min after the intravenous injection of 5-6 MBq/kg FDG in all patients. The PET images were interpreted visually, and tracer uptake was quantitated as the standardized uptake value adjusted to body weight (SUV) in the lesions showing FDG uptake. The accuracy of the PET results was assessed by a consensual verdict based on histology, cytology, other imaging and clinical follow-up. RESULTS: FDG PET correctly diagnosed 33 of 36 patients with recurrent disease and 12 of 15 patients without recurrence. On patient-based analysis, the sensitivity, specificity and accuracy of FDG PET were 91.7%, 80.0% and 88.2%, respectively, depending on the selected scheme for visual scoring of the lesions. The area index in receiver-operating characteristic analysis was 0.95 for patient detection. Malignant lesions accumulated significantly more FDG than the benign ones (the mean SUVs were 3.7 +/- 1.9 and 1.6 +/- 1.1, respectively, p = 0.004). The sensitivity and specificity in correct identification of tumor recurrence or metastases using a threshold SUV 1.9 were 88.8% and 66.7% in contrast to the visual analysis (sensitivity 96.4%, specificity 50%) on a lesion-based analysis. The partial volume effect of SUV in a few small lesions and the presence of bone lesions in which FDG uptake was relatively low might be the reason for the lower sensitivity in SUV analysis. FDG PET was valuable when CT/MRI was negative or inconclusive, and in patients with elevated tumor marker levels as well as with normal tumor marker levels when recurrence was suspected clinically. However, PET failed to visualize some small metastatic lesions in lung and bone, and showed falsely high FDG uptake in some benign lesions. CONCLUSION: The results indicated that FDG PET is a reliable and accurate diagnostic method for detecting recurrent or metastatic gynecologic cancer particularly lymph node metastases. Although the sensitivity of PET for detecting small metastases was relatively limited, the overall sensitivity of FDG PET was significantly higher than morphologic imaging.     

Inverse correlation between tumor perfusion and glucose uptake in human head and neck tumors

RATIONALE AND OBJECTIVES: We sought to determine the relationship between tumor blood flow and glucose uptake in head and neck tumors using perfusion computed tomography (PCT) and fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET). MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for this study. Sixteen patients (mean age, 67 years; age range, 36-89 years) who had known or suspected head and neck tumors (15 malignant tumors and one schwannoma) underwent PCT and FDG PET examinations. Tumor area was measured on conventional CT images. The PCT data were postprocessed using maximum slope method analysis, and standardized uptake value (SUV) was measured on FDG PET. RESULTS: Mean arterial perfusion of the tumors was 61.56 mL/min/100 mL (range 22.17-102.7 mL/min/100 mL), and mean FDG SUV was 7.48 (range 2.74-17.1). A significant negative correlation between arterial perfusion and FDG SUV was found for malignant tumors (r = -0.538, P = .04, n = 15). CONCLUSION: There was an inverse relationship between arterial perfusion and glucose uptake of head and neck malignant tumors, suggesting that the malignant tumors may depend on anaerobic glycolysis.     

Positron emission tomographic imaging with<Superscript>11</Superscript>C-choline in differential diagnosis of head and neck tumors: comparison with<Superscript>18</Superscript>F-FDG PET

The aim of this study was to evaluate the clinical value of positron emission tomography (PET) with¹¹C-labeled choline (CHOL) for the differential diagnosis of malignant head and neck tumors from benign lesions as compared with¹⁸F-fluorodeoxyglucose PET.Methods: We studied 45 patients (28 males, 17 females, age range, 29-84 years) with suspected lesions in the head and neck region using both CHOL and FDG PET within a 2-week period on each patient. All patients fasted for at least 6 hours for both the CHOL and FDG studies. PET imaging was performed 5 min and 50-60 min after intravenous injection of CHOL and FDG, respectively. After data acquisition, PET images were corrected for attenuation, and the reconstructed images were analyzed by visual interpretation. Then, the standardized uptake value (SUV) was calculated for semiquantitative evaluation of tumor tracer uptake. Finally the results of PET scans were compared with the histological diagnoses from surgical specimens or biopsies.Results: With CHOL PET, malignant tumors were correctly detected in 24 (96%) of 25 patients, and benign lesions in 14 (70%) of 20 patients with an accuracy of 84.4%. With FDG PET, malignancy was correctly diagnosed in 23 (92%) of 25 patients, and benign lesions in 13 (65%) of 20 patients resulting an accuracy of 80%. A significant positive correlation between CHOL and FDG SUVs was found for all lesions (r = 0.677, p = 0.004, n = 45). Malignant tumors showed significantly higher tracer accumulation than the benign lesions in both CHOL and FDG studies (5.69 ± 1.61, n = 25 vs. 2.98 ± 2.13, n = 20, p < 0.0001; 9.21 ± 4.23, n = 25 vs. 3.60 ± 2.57, n = 20, p < 0.0001). The cutoff SUV for differentiating malignant and benign lesions was 3.5 for CHOL and 3.9 for FDG. CHOL showed slightly better differentiation between malignant and benign lesions than FDG although some overlap existed on both studies. But the difference was not statistically significant.Conclusion: The results of this study indicate that CHOL PET may be feasible clinically for head and neck tumor imaging. PET imaging with CHOL seems to be able to detect malignant head and neck tumors as effectively as FDG PET. The advantages of CHOL PET were shorter examination period and low uptake in the muscle. However, both CHOL and FDG have some limitations in the evaluation of salivary gland lesions.     

Correlation between serum CEA level and metabolic volume as determined by FDG PET in postoperative patients with recurrent colorectal cancer

To determine the correlation between serum CEA level and the metabolic volume by FDG PET in postoperative patients with recurrent colorectal cancer, FDG PET was performed in 29 consecutive patients with recurrent or metastatic colorectal cancer whose CEA levels were higher than 5 ng/ml. A whole body emission scan was performed 60 minutes after injecting 370-555 MBq of F-18 FDG. "PET volume" and "PET metabolic volume" of tumors were measured on FDG PET images. Based on an isocontour plot of tumor mass at 2.5 SUV (standardized uptake value), the metabolically active tumor "PET volume" was calculated. "PET metabolic volume" was obtained by multiplying the "PET volume" by the mean SUV of the tumor. All recurrent or metastatic lesions were single or multiple lesions of measurable size (axial diameter > 1 cm, minimum "PET volume" 3.5 cm3), and were verified by operation or by other imaging modalities (CT or MRI). There was a linear associations between "PET volume" and serum CEA level. Further regression analysis by least squares showed a highly significant model with an equation of volume = 41.2 + 0.471 x CEA (r2 = 0.629). However, no such association was found between "PET metabolic volume" and serum CEA level according to the residual normality test. In conclusion, "PET volume" measured by FDG PET and serum CEA level in colorectal cancer are significantly correlated. Tumor volume determined by FDG PET can be used as an effective marker of tumor burden in postoperative patients with colorectal carcinoma.     

High incidence of chest malignancy detected by FDG PET in patients suspected of recurrent squamous cell carcinoma of the upper aerodigestive tract

OBJECTIVE: To determine the incidence of chest neoplasms detected by FDG PET in patients with previously treated squamous cell head and neck cancer (HNC), being evaluated for possible recurrent disease. METHODS: This is a retrospective review of 41 patients (M = 29, F = 12: average age = 58 years) with previously treated HNC who underwent FDG PET of the neck and chest as part of routine evaluation for locoregional and/or distant recurrence. Thirty-four of 41 patients had advanced stage III or IV HNC. All FDG PET studies were reviewed by dedicated nuclear medicine physicians, including evaluation for abnormal uptake in the chest. The chest FDG findings were correlated with serial chest radiographs or chest CT. The occurrence rate of incidental chest malignancy was determined and based on characteristic imaging findings, biopsy, and/or clinical course. RESULTS: Twelve of 41 patients had abnormal FDG uptake in the lungs and/or mediastinum. Ten of 12 patients were found to have neoplasms that could represent either metastases or a new lung primary. Five of these 10 were unsuspected neoplasms prior to FDG PET. The other 2/12 FDG PET scans in the chest were false positive. There was one false-negative FDG PET, with subsequent PET and CT demonstrating pulmonary metastases. Overall, there was a 27% incidence of chest malignancies in patients with advanced HNC being evaluated for possible recurrence. CONCLUSION: Our study demonstrated a chest malignancy in 1 out of 4 patients with advanced HNC being evaluated for locoregional and/or distant spread. Fifty percent were unsuspected prior to FDG PET. This result suggests that FDG PET of the lungs should be routinely included in the evaluation of high-risk patients.     

Comparative benefits and limitations of 18F-FDG PET and CT-MRI in documented or suspected recurrent cervical cancer

Purpose The purpose of this study was to assess the comparative benefits and limitations of ¹⁸F-fluorodeoxyglucose (FDG) PET and CT-MRI in documented or suspected recurrence of cervical cancer after primary treatment. Methods Three patient groups were enrolled. Group A patients had biopsy-documented recurrent or persistent cervical cancer. Group B patients had suspicion of recurrent tumour on CT-MRI without biopsy proof and were potentially curable. Group C patients were in complete remission after previous definitive treatment for histologically confirmed cervical carcinoma but had elevated serum squamous cell carcinoma antigen (tumour marker) levels despite negative CT-MRI. Clinical management decisions were recorded with CT-MRI alone and with additional FDG PET. Discordances and concordances between CT-MRI and FDG PET results were identified and related to final diagnosis as based on histopathology or follow-up. Results A total of 150 patients (ten regions per patient) were eligible for analysis, with 58 in group A, 52 in group B and 40 in group C. For the 149 discordant regions, 126 (84.6%) had final diagnoses. Of these final diagnoses, there was additional benefit from FDG PET over CT-MRI in 73.8% (93/126), with FDG PET correcting false negatives (FNs) on CT-MRI in 74.2% (69/93) and correcting false positives (FPs) on CT-MRI in 25.8% (24/93). Among lesions confirmed by FDG PET, 75.4% (52/69) were extra-pelvic. There was additional benefit of CT-MRI compared with FDG PET in 26.2% (33/126): in nine (27.3%) CT-MRI results were shown to be true positive (TP) whereas FDG PET yielded FN results, while in 24 (72.7%) CT-MRI corrected FP results on FDG PET. Among the nine FNs on FDG PET that were identified by CT-MRI, four were extra-pelvic. Among the FPs on FDG PET that were excluded by CT-MRI, 79.2% (19/24) were extra-pelvic. Conclusion For recurrent cervical cancer, the benefits of FDG PET exceed those of CT-MRI owing to the ability of FDG PET to identify extra-pelvic metastases and its higher sensitivity and specificity.     

The role of positron emission tomography/CT imaging in head and neck cancer patients after radical chemoradiotherapy

Objectives

Positron emission tomography with CT (PET/CT) scanning is increasingly being used in head and neck cancer to assess response after radical concomitant chemoradiotherapy. The purpose of this study was to assess the use of PET/CT following chemoradiotherapy at our institution.

Methods

All patients receiving radical chemoradiotherapy for head and neck cancer over a 9-year period were retrospectively identified. Outcome data including local control and overall survival were collected for all patients. The negative predictive value of PET/CT for local recurrence was calculated. Of those with a reported positive PET/CT scan the maximum standardised uptake values were compared with the incidence of local recurrence.

Results

92 patients were identified having a post-treatment PET/CT from a total of 301 patients receiving radical concomitant chemoradiotherapy. Median time from completion of chemoradiotherapy to PET/CT scan was 3 (range 2–8) months. Median follow-up in surviving patients was 19 and 25 months in the PET/CT and non-PET/CT groups, respectively. The negative predictive value for local recurrence was 91.8%. The median maximum standardised uptake values were 10.2 (range 3.1–33) and 6.89 (range 3.1–30) in those with local recurrence and with no local recurrence, respectively.

Conclusions

Post-chemoradiotherapy PET/CT may aid subsequent management decisions. Patients with a negative PET/CT scan after radical chemoradiotherapy have a 91.8% chance of remaining free of local recurrence 19 months post-treatment. A higher maximum standardised uptake value on the post-chemoradiotherapy PET/CT may predict subsequent local recurrence and warrants further investigation.

Advances in knowledge

Post-chemoradiotherapy PET/CT imaging aids subsequent management decisions.A large population of patients with head and neck squamous cell carcinomas are currently treated with radical concomitant chemoradiotherapy (CRT) in preference to surgery to achieve similar cure rates with less morbidity. There remains significant controversy and variation in practice over what constitutes optimal management of the post-CRT neck. Some centres offer all patients with node-positive disease a neck dissection, whereas others are now using positron emission tomography (PET) CT imaging to assess the post-CRT neck with a view to avoiding neck dissection in those who have had a complete radiological response.There is evidence that some patients being treated with definitive CRT will benefit from a post-CRT selective neck dissection through early resection of residual disease [1]. However, a large proportion of patients will have a complete pathological response post CRT [2], and if these patients can be accurately identified radiologically, unnecessary neck dissections may be avoided.The 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) standardised uptake value (SUV) is not well studied as a marker for assessing response and risk of recurrence after radical CRT. Pre-CRT mean FDG-SUV levels have previously been considered as a possible predictor of response, with conflicting results: 1 prospective study of 88 patients has shown that an increasing pre-treatment mean FDG-SUV of the primary tumour was associated with decreased disease-free survival [3]. Conversely, a similar study involving 77 patients has failed to show that the mean FDG-SUV is predictive of response to CRT [4]. A meta-analysis considering the role of PET/CT in assessing prognosis for head and neck cancer has recently been published. This confirms that FDG uptake, as measured by the SUV, is valuable for predicting long-term survival in head and neck cancer. High FDG uptake may be useful for identifying patients requiring more aggressive treatment [5]. Difficulties regarding the interpretation of FDG uptake post-CRT have been well documented as a result of potential false positives due to post-treatment inflammation or infection [6].The purpose of this study was to assess the role of PET/CT following CRT at our institution in predicting local recurrence. The use of the maximum FDG-SUV (SUV_max) on the post-CRT PET/CT as a predictor of subsequent local recurrence was also evaluated.     

Diagnostic usefulness of FDG PET for pancreatic mass lesions

The purpose of this study was to investigate the feasibility of [18F]2-deoxy-2-fluoro-D-glucose (FDG) positron emission tomography (PET) in patients with a pancreatic mass by comparing the results with those of X-ray computed tomography (CT) and magnetic resonance (MR) imaging. METHODS: Eighty-six patients with pancreatic lesions, included 65 malignant tumors and 21 benign masses (55 masses were proven histologically and the others were diagnosed clinically), were studied. The diagnostic factors of CT and MR imaging were evaluated, and those of FDG PET were also evaluated for malignant and benign masses by visual interpretation and quantitative interpretation with the standardized uptake value (SUV) and SUVgluc which was designed to reduce the effects of a high blood sugar level. Visual interpretations were evaluated only in FDG PET images, and quantitative interpretations were evaluated by referring to CT and/or MR imaging. The correlation between SUV and the degree of histological differentiation in pancreatic ductal adenocarcinoma was investigated. RESULTS: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for CT imaging were 91, 62, 88, 68 and 84%, and for MR imaging 78, 70, 88, 54 and 76%, respectively. In visual interpretation of FDG PET images, the sensitivity, specificity, PPV, NPV and accuracy were 82, 81, 93, 59 and 81%, respectively. Significant differences between malignant and benign lesions existed in SUV and SUVgluc (p < 0.0001, each). With the cutoff value of SUV as 2.1 and SUVgluc as 2.2, the accuracy of diagnosis was maximal. With that cutoff value, the sensitivity, specificity, PPV, NPV and accuracy for SUV were 89, 76, 92, 70 and 86%, and for SUVgluc 91, 76, 92, 73 and 87%, respectively. The sensitivity and NPV of SUVgluc were higher than those of SUV, which suggests that SUVgluc may be more useful in reducing the number of overlooked malignant tumors. The specificity and PPV of FDG PET were superior to those of CT and MR imaging. There were no significant differences between the SUVs of moderately differentiated adenocarcinomas and those of well differentiated adenocarcinomas. CONCLUSION: To improve the diagnostic procedure for classifying masses, FDG PET with not only SUV but also SUV corrected by the blood sugar level is required in addition to morphological diagnosis by CT and/or MR imaging.     

F-18 FDG PET/CT in the management of thyroid cancer

PURPOSE: There are approximately 32,000 new cases of thyroid carcinoma annually in the United States. F-18 FDG PET/CT has an established role in cancer management, including thyroid cancer, usually in patients who are thyroglobulin (Tg) positive/iodine negative. We reviewed our experience with F-18 FDG PET/CT in thyroid cancer, with an emphasis on correlation with Tg, and maximum standardized uptake values (SUV). We also analyzed the role of thyroid stimulating hormone (TSH) on PET/CT results. MATERIALS AND METHODS: This is a retrospective study (January 2003 to December 2006) of 76 patients with differentiated thyroid cancer, who had F-18 FDG PET/CT scans. There were 44 women and 32 men, with age range of 20 to 81 years (average, 51.1 +/- 18.1). The administered doses of F-18 FDG ranged from 396 to 717 MBq (15.8-19.4 mCi) (average, 566 +/- 74.8) (15.3 +/- 2). Reinterpretation of the imaging studies for accuracy and data analysis from medical records were performed. RESULTS: A total of 98 PET/CT scans were analyzed (59 patients had 1 scan, 12 patients had 2, and 5 patients had 3). PET/CT was 88.6% sensitive (95% CI: 78.-94.3) and 89.3% specific (95% CI: 71.9-97.1). Mean Tg level was 1203 ng/mL (range, 0.5-28,357) in patients with positive PET/CT and 9.72 ng/mL (range, 0.5-123.0) in patients with negative PET/CT scans (P = 0.0389). Mean SUV max was 10.8 (range, 2.5-32) in the thyroid bed recurrence/residual disease and 7.53 (range, 2.5-26.2) in metastatic lesions (P = 0.0114). Mean SUV max in recurrent/residual disease in patients with TSH 30 mIU/L was 8.1 (range, 2.6-32) (P = 0.2994). CONCLUSION: F-18 FDG PET/CT had excellent sensitivity (88.6%) and specificity (89.3%) in this patient population. Metastatic lesions were reliably identified, but were less F-18 FDG avid than recurrence/residual disease in the thyroid bed. TSH levels at the time of PET/CT did not appear to impact the FDG uptake in the lesions or the ability to detect disease. In the setting of high or rising levels of Tg, our study confirms that it is indicated to include PET/CT in the management of patients with differentiated thyroid cancer.