18F-FET与18F-FDG PET显像对照研究

目的探讨O（2-[^18F]氟代乙基）-L-酪氨酸（^18F—FET）对肿瘤的探测能力。方法2例脑瘤患者，用于了解^18F—FETPET显像的全身分布情况。经病理检查或手术证实的其他部位肿瘤患者12例（肺癌6例，胰腺癌、神经内分泌肿瘤各2例，肾上腺皮质癌、鼻咽癌各1例），均有近期CT检查，少数行MRI或全身骨显像检查，1周内分别行^18F—FET与^18F-脱氧萄萄糖（FDG）PET显像。结果①^18F—FET主要经泌尿及胆道系统排泄，骨骼、软组织及心、肝等仅轻度摄取，标准摄取值（SUV）0．38—1．64，肠道、胰腺基本不显影。②12例肿瘤患者^18F—FDGPET显像共检出110个病灶，^18F—FET仅检出15个，病灶的SUV也明显低于^18F—FDG。^18F—FET不仅对一些^18F—FDG代谢活性高的孤立病灶显示不清，对小病灶的检出率也明显低于^18F—FDG。结论^18F—FETPET显像对肺癌、胰腺癌、肾上腺皮质癌等的探测能力明显低于^18F—FDG。     

Early tumor response to Hsp90 therapy using HER2 PET: comparison with 18F-FDG PET.

We compared (68)Ga-DOTA-F(ab')(2)-herceptin (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N',N'-tetraacetic acid [HER2 PET]) and (18)F-FDG PET for imaging of tumor response to the heat shock protein 90 (Hsp90) inhibitor 17-allylamino-17-demethoxygeldanamycin (17AAG). METHODS: Mice bearing BT474 breast tumor xenografts were scanned with (18)F-FDG PET and HER2 PET before and after 17AAG treatment and then biweekly for up to 3 wk. RESULTS: Within 24 h after treatment, a significant decrease in HER2 was measured by HER2 PET, whereas (18)F-FDG PET uptake, a measure of glycolysis, was unchanged. Marked growth inhibition occurred in treated tumors but became evident only by 11 d after treatment. Thus, Her2 downregulation occurs independently of changes in glycolysis after 17AAG therapy, and Her2 reduction more accurately predicts subsequent tumor growth inhibition. CONCLUSION: HER2 PET is an earlier predictor of tumor response to 17AAG therapy than (18)F-FDG PET.     

18F-FDOPA PET imaging of brain tumors: comparison study with 18F-FDG PET and evaluation of diagnostic accuracy.

We evaluated the amino acid and glucose metabolism of brain tumors by using PET with 3,4-dihydroxy-6-(18)F-fluoro-l-phenylalanine ((18)F-FDOPA) and (18)F-FDG. METHODS: Eighty-one patients undergoing evaluation for brain tumors were studied. Initially, 30 patients underwent PET with (18)F-FDOPA and (18)F-FDG within the same week. Tracer kinetics in normal brain and tumor tissues were estimated. PET uptake was quantified by use of standardized uptake values and the ratio of tumor uptake to normal hemispheric tissue uptake (T/N). In addition, PET uptake with (18)F-FDOPA was quantified by use of ratios of tumor uptake to striatum uptake (T/S) and of tumor uptake to white matter uptake. The accuracies of (18)F-FDOPA and (18)F-FDG PET were determined by comparing imaging data with histologic findings and findings of clinical follow-up of up to 31 mo (mean, 20 mo). To further validate the accuracy of (18)F-FDOPA PET, (18)F-FDOPA PET was performed with an additional 51 patients undergoing brain tumor evaluation. RESULTS: Tracer uptake in tumors on (18)F-FDOPA scans was rapid, peaking at approximately 15 min after intravenous injection. Tumor uptake could be distinguished from that of the striatum by the difference in peak times. Both high-grade and low-grade tumors were well visualized with (18)F-FDOPA. The sensitivity for identifying tumors was substantially higher with (18)F-FDOPA PET than with (18)F-FDG PET at comparable specificities, as determined by simple visual inspection, especially for the assessment of low-grade tumors. Using receiver-operating-characteristic curve analysis, we found the optimal threshold for (18)F-FDOPA to be a T/S of greater than 1.0 (sensitivity, 96%; specificity, 100%) or a T/N of greater than 1.3 (sensitivity, 96%; specificity, 86%). The high diagnostic accuracy of (18)F-FDOPA PET at these thresholds was confirmed with the additional 51 patients (a total of 81 patients: sensitivity, 98%; specificity, 86%; positive predictive value, 95%; negative predictive value, 95%). No significant difference in tumor uptake on (18)F-FDOPA scans was seen between low-grade and high-grade tumors (P = 0.40) or between contrast-enhancing and nonenhancing tumors (P = 0.97). Radiation necrosis was generally distinguishable from tumors on (18)F-FDOPA scans (P < 0.00001). CONCLUSION: (18)F-FDOPA PET was more accurate than (18)F-FDG PET for imaging of low-grade tumors and evaluating recurrent tumors. (18)F-FDOPA PET may prove especially useful for imaging of recurrent low-grade tumors and for distinguishing tumor recurrence from radiation necrosis.     

PET/CT of skull base meningiomas using 2-18F-fluoro-L-tyrosine: initial report.

Precise delineation of the shape of skull base meningiomas is critical for their treatment and follow-up but is often difficult using conventional imaging such as CT and MRI. We report our results with PET/CT and 2-(18)F-fluoro-L-tyrosine ((18)F-TYR), a marker of amino acid transport, as part of the yearly follow-up of irradiated patients. METHODS: Eleven patients (mean age, 56.5 y) with skull base meningiomas (n=13 lesions) previously irradiated were included. All patients received 300 MBq of (18)F-TYR and were imaged after 30 min of uptake, using a dedicated PET/CT system. The images were first visually examined, and regions of interest (ROI) were then placed over the transaxial PET slice showing the highest uptake. Another ROI was placed over the normal parietal cortex. Tumor-to-cortex activity ratios were obtained by dividing the maximum pixel value in the tumor ROI by the maximum pixel value in the cortex ROI. The PET/CT images were compared with the MR images obtained as part of routine follow-up. RESULTS: Accumulation of the tracer was higher in all meningiomas than in the surrounding tissue. The tumor-to-cortex activity ratio was 2.53 +/- 0.35 (range, 1.3-6). Nonneoplastic tissue such as hyperemic cavernous sinus did not take up the radionuclide and was therefore easily distinguished from the meningioma. The (18)F-TYR anomalies completely overlapped with the MR image in 54% of the tumors, extended beyond the MRI lesion in 38% of the tumors, and were smaller in 8% of the tumors. CONCLUSION: Meningiomas of the skull base are clearly visualized using (18)F-TYR PET/CT, even after irradiation. In addition to MRI, (18)F-TYR PET/CT images may contribute to the evaluation, delineation, and follow-up of these tumors.     

Whole-body (18)F-FDG PET identifies high-risk myeloma.

The purpose of this study was to evaluate the clinical utility of whole-body PET with (18)F-FDG in patients with multiple myeloma and related monoclonal diseases. METHODS: Between July 1, 1996, and July 2000, 98 (18)F-FDG PET scans were obtained for 66 patients, with 25 patients having 2 or more scans. The results were compared with routine clinical and staging information, including CT and MRI scans, as indicated. Of the 66 patients, 16 had previously untreated active myeloma, 14 had monoclonal gammopathy of undetermined significance (MGUS), 10 had disease in remission, and 26 had relapsing disease. RESULTS: Negative whole-body (18)F-FDG PET findings reliably predicted stable MGUS. Of the 14 MGUS patients with follow-up of 3-43+ mo, myeloma has developed in only 1 (7%), at 8 mo. Conversely, the 16 previously untreated patients with active myeloma all had focal or diffusely positive scan findings. Four (25%) of 16 previously untreated patients with positive (18)F-FDG PET findings had negative full radiologic surveys. Another 4 (25%) of 16 patients had focal extramedullary disease. This was confirmed by biopsy or other imaging techniques. Extramedullary uptake also occurred in 6 (23%) of 26 patients with relapse. This extramedullary uptake was a very poor prognostic factor both before treatment and at relapse. For example, median survival was 7 mo for patients with disease relapse. Persistent positive (18)F-FDG PET findings after induction therapy predicted early relapse. In 13 (81%) of 16 patients with relapsing disease, new sites of disease were identified. The (18)F-FDG PET results were especially helpful in identifying focal recurrent disease in patients with nonsecretory or hyposecretory disease amenable to local irradiation therapy, which was used in 6 patients. CONCLUSION: Whole-body (18)F-FDG PET provides important prognostic information, which is clinically useful and complementary to conventional methods of evaluating plasma cell disorders. (18)F-FDG PET is a unique tool for evaluation of nonsecretory myeloma. Residual or recurrent disease after therapy, especially extramedullary disease, is a poor prognostic factor.     

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。     

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.     

Whole-body 18F-FDG PET in recurrent or metastatic nasopharyngeal carcinoma.

The aim of this retrospective study was to evaluate the sensitivity and prognostic significance of whole-body (18)F-FDG PET for nasopharyngeal carcinoma (NPC) patients for whom there was a suspicion of recurrence or metastasis by conventional radiologic or clinical findings during their follow-up examinations. METHODS: Whole-body (18)F-FDG PET examinations were performed on 64 Taiwanese NPC patients (14 female, 50 male; mean age +/- SD, 45.8 +/- 13.0 y; age range, 16-75 y) 4-70 mo (mean +/- SD, 14.1 +/- 13.5 mo) after radiotherapy or induction chemotherapy followed by concurrent chemoradiotherapy from February 1997 to May 2001. The accuracy of (18)F-FDG PET detection for each patient was determined by the histopathologic results or other clinical evidence. RESULTS: The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of (18)F-FDG PET images in the diagnosis of NPC recurrence or metastases and secondary primary cancers were 92%, 90%, 92%, 90%, and 91%, respectively. Furthermore, the presence of (18)F-FDG hypermetabolism was highly correlated with the survival time of NPC patients. CONCLUSION: Whole-body (18)F-FDG PET is a sensitive follow-up diagnostic tool for the evaluation of NPC recurrences and metastases. It is also an effective prognostic indicator for NPC patients. To determine the optimized utilization of (18)F-FDG PET in the follow-up for NPC patients, further cost-effectiveness analysis of (18)F-FDG PET in combination with conventional management is necessary.     

18F-FLT PET for visualization of laryngeal cancer: comparison with 18F-FDG PET.

The feasibility of (18)F-3'-fluoro-3'-deoxy-L-thymidine PET (FLT PET) for detecting laryngeal cancer was investigated and compared with (18)F-FDG PET. METHODS: Eleven patients diagnosed with or strongly suspected of having recurrent laryngeal cancer and 10 patients with histologically proven primary laryngeal cancer underwent attenuation-corrected (18)F-FLT PET imaging 60 min after injection of a median of 213 MBq (range, 175-400 MBq) (18)F-FLT and attenuation-corrected (18)F-FDG PET imaging 90 min after injection of a median of 340 MBq (range, 165-650 MBq) (18)F-FDG. All patients were staged by endoscopy and CT according to the Union Internationale Contre la Cancer TNM staging system. All patients underwent biopsy of the laryngeal area after imaging. Lesions seen on (18)F-FDG PET and (18)F-FLT PET were compared with histopathologic results. Mean SUVs, maximum SUVs, and tumor-to-nontumor (TNT) ratios were calculated for (18)F-FLT and (18)F-FDG. Wilcoxon nonparametric testing was used for comparison of (18)F-FDG with (18)F-FLT uptake. The Spearman correlation coefficient was used to correlate mean SUVs, maximum SUVs, and TNT ratios of (18)F-FDG PET and (18)F-FLT PET. Two-tailed P values < 0.05 were considered significant. RESULTS: (18)F-FDG PET and (18)F-FLT PET detected laryngeal cancer correctly in 15 of 17 patients. One lesion judged as positive on (18)F-FDG PET turned out to be normal tissue. Of 2 lesions judged as positive on (18)F-FLT PET, 1 turned out to be inflammation and the other to be normal tissue. Maximum SUVs were 3.3 (range, 1.9-8.5) for (18)F-FDG and 1.6 (range, 1.0-5.7) for (18)F-FLT (P < 0.001). Mean SUVs were 2.7 (range, 1.5-6.5) for (18)F-FDG and 1.2 (range, 0.8-3.8) for (18)F-FLT (P < 0.001). TNT was 1.9 (range, 1.3-4.7) for (18)F-FDG and 1.5 (range, 1.1-3.5) for (18)F-FLT (P < 0.05). CONCLUSION: The numbers of laryngeal cancers detected with (18)F-FLT PET and (18)F-FDG PET were equal. In laryngeal cancer, the uptake of (18)F-FDG is higher than that of (18)F-FLT.     

Whole-body hybrid PET with 18F-FDG in the staging of non-Hodgkin's lymphoma.

PET with a double-head gamma camera (hybrid PET) is a new approach to tumor imaging with 18F-FDG. This study was conducted to clarify the feasibility of whole-body FDG hybrid PET in the staging of non-Hodgkin's lymphoma (NHL) in comparison with PET with a dedicated camera (dedicated PET) and to compare the results of both FDG studies with those of CT and 67Ga scanning as conventional imaging studies (CIS). METHODS: Thirty patients with NHL were prospectively evaluated. The results of the imaging studies regarding detection of the sites involved and staging were compared with each other and with those of the reference standard based on the final overall clinical evaluation. RESULTS: Of the total of 206 sites, whole-body FDG hybrid PET and dedicated PET detected 159 sites (77.2%) and 179 sites (86.9%), respectively. Eighteen of the 20 sites missed by hybrid PET alone consisted of lesions < 1.5 cm. Both FDG studies provided concordant staging results in all but 2 patients. CIS, on the other hand, detected 164 (79.6%) of the 206 sites, 137 of which were also detected by hybrid PET. Hybrid PET detected an additional 22 sites not found by CIS, whereas CIS detected 27 additional sites. Hybrid PET and CIS provided concordant staging results in 19 patients. Hybrid PET correctly staged NHL in 5 additional patients, whereas CIS correctly staged NHL in only 1 additional patient. CONCLUSION: Whole-body FDG hybrid PET appeared to be an accurate method of staging NHL. Despite its poorer image quality compared with dedicated PET, hybrid PET provided NHL staging results comparable with those of dedicated PET. Hybrid PET also yielded results comparable with those of CIS. However, whole-body FDG hybrid PET is currently inadequate as a single modality for staging NHL and is complementary to CT.     

The usefulness of 18F-FDG PET/MRI fusion image in diagnosing pancreatic tumor: comparison with 18F-FDG PET/CT

Purpose

This study aimed at demonstrating the feasibility of retrospectively fused ¹⁸F FDG-PET and MRI (PET/MRI fusion image) in diagnosing pancreatic tumor, in particular differentiating malignant tumor from benign lesions. In addition, we evaluated additional findings characterizing pancreatic lesions by FDG-PET/MRI fusion image.

Methods

We analyzed retrospectively 119 patients: 96 cancers and 23 benign lesions. FDG-PET/MRI fusion images (PET/T1 WI or PET/T2WI) were made by dedicated software using 1.5 Tesla (T) MRI image and FDG-PET images. These images were interpreted by two well-trained radiologists without knowledge of clinical information and compared with FDG-PET/CT images. We compared the differential diagnostic capability between PET/CT and FDG-PET/MRI fusion image. In addition, we evaluated additional findings such as tumor structure and tumor invasion.

Results

FDG-PET/MRI fusion image significantly improved accuracy compared with that of PET/CT (96.6 vs. 86.6 %). As additional finding, dilatation of main pancreatic duct was noted in 65.9 % of solid types and in 22.6 % of cystic types, on PET/MRI-T2 fusion image. Similarly, encasement of adjacent vessels was noted in 43.1 % of solid types and in 6.5 % of cystic types. Particularly in cystic types, intra-tumor structures such as mural nodule (35.4 %) or intra-cystic septum (74.2 %) were detected additionally. Besides, PET/MRI-T2 fusion image could detect extra benign cystic lesions (9.1 % in solid type and 9.7 % in cystic type) that were not noted by PET/CT.

Conclusions

In diagnosing pancreatic lesions, FDG-PET/MRI fusion image was useful in differentiating pancreatic cancer from benign lesions. Furthermore, it was helpful in evaluating relationship between lesions and surrounding tissues as well as in detecting extra benign cysts.     

Grading of brain glioma with 1-11C-acetate PET: comparison with 18F-FDG PET

The objective of this study is to reevaluate the clinical significance of 1-11C-acetate (ACE) positron emission tomography (PET) in patients with brain glioma, in comparison with 18F-fluorodeoxyglucose (FDG) PET. METHODS: Ten patients with histologically proven glioma were included in this study. They underwent PET examination with both FDG and ACE on separate days. For ACE PET, 20-min data acquisition was performed just after the administration of 740 MBq of ACE; 10-20-min data were used for the analysis. FDG PET data acquisition for 10 min started 60 min postinjection of 370 MBq of FDG, approximately. Both reconstructed images were converted to standardized uptake value (SUV) images for patient body weight and injected dose. Regions of interest were placed on the tumor and the contralateral cerebral cortex, and SUV and tumor-to-cortex ratio (T/C) were calculated; these values were compared between high- and low-grade gliomas. RESULTS: SUV and T/C of ACE PET showed significant difference (SUV: 2.63+/-0.46 vs. 1.85+/-0.56, P=.03; T/C: 2.36+/-0.63 vs. 1.14+/-0.36, P=.02). In contrast, FDG PET revealed no significant difference in SUV or T/C between high- and low-grade gliomas (SUV: 7.13+/-4.31 vs. 4.71+/-1.27, P=.31; T/C: 0.98+/-0.55 vs. 0.62+/-0.09, P=.22). CONCLUSION: This preliminary study revealed that ACE PET is a promising tracer for the grading of brain glioma.     

FDG肿瘤显像相关分子机制研究进展

18F-FDG(18F-氟代脱氧葡萄糖)PET显像是依靠不同组织对18F-FDG的吸收差异来完成的,18F-FDG在肿瘤中的摄取增高与肿瘤的代谢及增殖情况、病理分级、分化程度、细胞的增生活性、倍增时间等生物学特性密切相关。进一步研究FDG吸收机制,将有助于对肿瘤的生物学特性更深一步的了解。     

18F-FDG显像对淋巴瘤分期及疗效评价的价值

目的探讨18F-脱氧葡萄糖(FDG)PET和PET/CT显像在淋巴瘤诊断、分期及疗效评价中的价值.方法 107例淋巴瘤或淋巴瘤疑似患者行18F-FDG PET或PET/CT显像,其中16例多次行PET或PET/CT显像.所有患者皆经病理学检查确诊,随访时间>6个月.结果淋巴瘤31例,PET显像阳性30例(96.8%),7例淋巴结转移癌及活动性淋巴结结核PET显像均为阳性,淋巴瘤与原发灶不明的淋巴结转移癌及活动性淋巴结结核难以鉴别.37%(10/27例)初诊淋巴瘤PET显像多发现恶性病灶而提高临床分期.16例淋巴瘤行多次PET显像,发现8例治疗后病灶消失,2例缓解,1例肿瘤复发,5例无瘤生存,皆与临床相符.53例淋巴瘤治疗后行PET显像,其中8例临床确认有肿瘤复发或明显残余,PET显像均为阳性;45例临床疗效为完全缓解(CR)和部分缓解(PR)的患者中,PET显像阳性者18例,3例肿瘤处于活跃状态,15例(非霍奇金淋巴瘤12例,霍奇金淋巴瘤3例)处于抑制状态,PET显像后改变了进一步临床治疗方案.结论 18F-FDG PET显像对检测淋巴瘤的体内分布及分期灵敏、准确、全面,但难以与活动性淋巴结结核、原发灶不明的淋巴结转移癌相鉴别.18F-FDG PET显像能灵敏、准确地检出淋巴瘤复发及残余病灶,对疗效评价及指导临床治疗有重要价值.     

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.     

18F-FDG PET显像诊断肾上腺肿瘤

目的　评价1 8F 脱氧葡萄糖 (FDG)PET显像对肾上腺肿瘤的诊断价值。方法　对 2 1例肾上腺肿瘤患者共 2 2个肾上腺病灶行1 8F FDGPET显像 ,对显像结果进行定性和半定量分析 ,并与CT和 (或 )MRI、针刺活组织检查、术后病理检查结果进行对比研究。结果　 9例肾上腺病灶处无明显FDG浓集 ,PET显像诊断为良性病变 ;12例病灶处FDG明显浓集 ,诊断为恶性病变。与病理检查结果比较 ,PET显像定性准确性为 10 0 % ,CT和 (或 )MRI为 6 4 %。良性病变与周围正常组织 (T N)放射性比值为 0 3～ 1 3,平均为 0 7,标准摄取值 (SUV)为 0 98～ 3 89,平均为 1 89;恶性病变T N比值为 3 1～15 1,平均为 6 9,SUV为 3 10～ 15 5 2 ,平均为 6 4 1,两组间差异均有显著性 (P均 <0 0 0 1)。病变性质与肿块大小无相关性。其中 4例PET显像发现了CT和 (或 )MRI未发现的局部淋巴结和远处转移灶12处。结论　1 8F FDGPET显像对肾上腺肿瘤定性诊断的准确性明显高于CT和 (或 )MRI。     

Whole-body 18F-FDG PET/CT in the presence of truncation artifacts.

We investigated the effect of CT truncation in whole-body (WB) PET/CT imaging of large patients, and we evaluated the efficacy of an extended field-of-view (eFOV) correction technique. METHODS: Two uniform phantoms simulating a "torso" and an "arms-up" setup were filled with (18)F-FDG/water. A third, nonuniform "body phantom was prepared with hot and cold lesions. All 3 phantoms were positioned in the center of the PET/CT gantry with >or=10% of their volume extending beyond the maximum CT FOV. An eFOV algorithm was used to estimate complete CT projections from nonlinear extrapolation of the truncated projections. CT-based attenuation correction (CT AC) of the phantom data was performed using CT images reconstructed from truncated and extended projections. For clinical validation, we processed truncated datasets from 10 PET/CT patients with and without eFOV correction. RESULTS: When using truncated CT images for CT AC, PET tracer distribution was suppressed outside the transverse CT FOV in phantom and patient studies. PET activity concentration in the truncated regions was only 10%-32% of the true value but increased to 84%-100% when using the extended CT images for CT AC. At the same time, the contour of phantoms and patients was recovered to the anatomically correct shape from the uncorrected emission images, and the apparent distortion of lesions near the maximum CT FOV was reduced. CONCLUSION: Truncation artifacts in WB PET/CT led to visual and quantitative distortions of the CT and attenuation-corrected PET images in the area of truncation. These artifacts can be corrected to improve the accuracy of PET/CT for diagnosis and therapy response evaluation.     

Solid splenic masses: evaluation with 18F-FDG PET/CT.

Our objective was to assess the role of (18)F-FDG PET/CT in the evaluation of solid splenic masses in patients with a known malignancy and in incidentally found lesions in patients without known malignancy. METHODS: Two groups of patients were assessed: (a) 68 patients with known malignancy and a focal lesion on PET or a solid mass on CT portions of the PET/CT study; and (b) 20 patients with solid splenic masses on conventional imaging without known malignancy. The standard of reference was histology (n = 16) or imaging and clinical follow-up (n = 72). The lesion size, the presence of a single versus multiple splenic lesions, and the intensity of (18)F-FDG uptake expressed as a standardized uptake value (SUV) were recorded. The ratio of the SUV in the splenic lesion to the background normal splenic uptake was also calculated. These parameters were compared between benign and malignant lesions within each of the 2 groups of patients and between the 2 groups. RESULTS: The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of (18)F-FDG PET/CT in differentiating benign from malignant solid splenic lesions in patients with and without malignant disease were 100%, 100%, 100%, and 100% versus 100%, 83%, 80%, and 100%, respectively. In patients with known malignant disease, an SUV threshold of 2.3 correctly differentiated benign from malignant lesions with the sensitivity, specificity, PPV, and NPV of 100%, 100%, 100%, and 100%, respectively. In patients without known malignant disease, false-positive results were due to granulomatous diseases (n = 2). CONCLUSION: (18)F-FDG PET can reliably discriminate between benign and malignant solid splenic masses in patients with known (18)F-FDG-avid malignancy. It also appears to have a high NPV in patients with solid splenic masses, without known malignant disease. (18)F-FDG-avid splenic masses in patients without a known malignancy should be further evaluated as, in our series, 80% of them were malignant.     

Whole-body (18)F-FDG PET and conventional imaging for predicting outcome in previously treated breast cancer patients.

This study was conducted to determine the ability of (18)F-FDG PET and conventional imaging (CI) to predict the outcomes in breast cancer patients who have previously undergone primary treatment. METHODS: The study population consisted of 61 female patients (median age, 54 y; range, 32--91 y) who were reevaluated with (18)F-FDG PET and CI after treatment. The median interval between the last treatment and PET was 0.4 y (range, 0--16 y). PET was performed within 3 mo of CI (median interval, 25 d; range, 2--84 d). To determine the independent impact of PET on outcome, PET images were reinterpreted in a blind fashion. Availability of clinical information after PET scanning (21 plus minus 12 mo) was required for study inclusion. Study endpoints were clinical evidence of progression of disease or death. RESULTS: Of 61 patients, 19 (31.1%) had no clinical evidence and 38 (62.3%) had evidence of residual or recurrent disease by the end of follow-up. Four patients (6.6%) had died. The positive and negative predictive values (PPV and NPV, respectively) of PET were 93% and 84%, respectively. CI yielded a PPV of 85% and an NPV of 59%. The prognostic accuracy of single whole-body PET was superior to that of multiple procedures with CI (90% vs. 75%; P < 0.05). Kaplan--Meier estimates of disease-free survival in patients with negative PET findings compared with those with positive PET findings revealed a significant difference between the 2 curves (log-rank test = 0.001). Kaplan--Meier estimates of disease-free survival stratified by CI results showed a marginally significant difference between CI-positive and CI-negative patients (log-rank test = 0.04). CONCLUSION: FDG PET can be used to improve prediction of the clinical outcome of previously treated breast cancer patients relative to what is achievable through CI alone.