Sequential positron emission tomography using [18F]fluorodeoxyglucose for monitoring response to chemotherapy in metastatic breast cancer.

PURPOSE: To evaluate the clinical value of positron emission tomography (PET) for monitoring chemotherapy in metastatic breast cancer. EXPERIMENTAL DESIGN: Twenty patients with hormonorefractory or hormonoreceptor-negative multimetastatic breast cancer were prospectively included. PET studies were done at baseline, at day 21 after the first cycle and at day 21 after the third cycle of chemotherapy. Metabolic response was defined based on visual and various modes of standardized uptake value (SUV) analysis of sequential PET studies. RESULTS: After one cycle, PET indicated a partial response in 12 patients, stable disease in 7 patients, and progressive disease in 1 patient, according to the visual analysis. After three cycles, PET showed a complete response in 5 patients, partial response in 11 patients, stable disease in 3 patients, and progressive disease in 1 patient. Seventy-five percent of the patients showing a metabolic response on visual analysis effectively responded to the treatment. The average SUV decreased on both the second and the third PET study, but only changes measured after three cycles of chemotherapy predicted the clinical response to chemotherapy and the overall survival. All methods for calculating the SUV (normalized for body weight, body surface area, or lean body mass) provided similar results. CONCLUSION: Semiquantitative analysis of [18F]fluorodeoxyglucose-PET studies done after three cycles of chemotherapy is useful for monitoring the response to chemotherapy in metastatic breast cancer.     

Evaluation of good clinical response to neoadjuvant chemotherapy in primary breast cancer using [18F]-fluorodeoxyglucose positron emission tomography

To determine whether [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) can predict complete pathological response (pCR) in patients achieving a good clinical response to neoadjuvant chemotherapy for primary breast cancer, 10 patients underwent FDG PET scanning prior to definitive breast surgery. Scan reports were compared with histopathological findings. No abnormal uptake at the primary tumour site was visualised in any patient. 9 of the 10 patients had residual invasive carcinoma at operation, ranging from 2 to 20 mm in maximum dimension. One patient achieved a complete pathological response. Of the 5 patients who underwent axillary surgery, no axillary FDG uptake was seen preoperatively although 3 of the 5 were histologically node-positive. FDG PET did not reliably identify residual disease in this series of good clinical responders to neoadjuvant chemotherapy, and its discriminatory power as a tool to predict complete pathological response therefore appears to be inadequate for clinical use in this setting.     

^18F—FDG PET／CT对乳腺癌新辅助化疗疗效预测的价值

目的探讨18F-FDG PET/CT评估乳腺癌新辅助化疗疗效的价值.方法 34例初治乳腺癌患者,采用标准CAF方案化疗2～4个周期,平均3.64周期,于治疗前、第一周期及第二周期化疗结束时共行84例次PET/CT检查,比较最大标准摄取值 (maximal standard uptake value, SUVmax)的变化.化疗结束后行手术,以病理结果作为PET/CT预测疗效的金标准,分为大体残留病变(gross residual disease, GRD)和微小残留病变(minimal residual disease, MRD)两组.采用第一周期化疗后SUVmax是否降到基础值的52%作为评估MRD和GRD的标准.结果第一周期化疗结束后GRD组和MRD组的SUVmax变化差异有显著性,SUVmax比值预测病理反应的准确性为89.0%,预测GRD组和MRD组特异性分别为83.0%和90.0%.结论 18F-FDG PET/CT在第一周期化疗结束后即可准确鉴别出化疗有效的病例,从而避免对新辅助化疗无效者的过度治疗,支持有效者继续化疗.     

18F-Fluorodeoxyglucose positron emission tomography optimizes neoadjuvant chemotherapy for primary breast cancer to achieve pathological complete response

Background

To assess the usefulness of positron emission tomography combined with computed tomography using ¹⁸F-fluorodeoxyglucose (FDG PET/CT) for optimizing chemotherapy during neoadjuvant chemotherapy for primary breast cancer.

Methods

One hundred and eight patients (110 tumors) with breast cancer (??2?cm, stages II and III) received neoadjuvant chemotherapy consisting of an anthracycline-based regimen and taxane. The maximal value of the baseline standardized uptake value (SUV) and the change in SUV after four cycles of an anthracycline-based regimen relative to baseline SUV were assessed for predicting pathological complete response (pCR) after sequential taxane.

Results

Tumors with pCR had significantly higher baseline SUV (9.3?±?3.7 SD) compared to those with non-pCR (7.2?±?3.8 SD) (p?=?0.02), but there was a considerable overlap between two groups. On PET scan after four cycles of chemotherapy, thirty-three patients (33.7%) with a 72.1% or greater reduction in SUV were considered as responders and the performance in predicting pCR had a sensitivity of 88.9% and specificity of 78.7%.

Conclusion

The baseline SUV could not be a useful indicator for predicting pCR due to the wide range in sensitivity. On the other hand, a relative change in SUV after completion of an anthracycline-based regimen could be useful for predicting pCR.     

18F]fluorodeoxyglucose uptake by positron emission tomography predicts outcome of non-small-cell lung cancer.

PURPOSE: To determine whether the standardized uptake value (SUV) of [(18)F]fluorodeoxyglucose uptake by positron emission tomography could be a prognostic factor for non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: One hundred sixty-two patients with stage I to IIIb NSCLC were analyzed. Overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and local-regional control (LRC) were calculated by the Kaplan-Meier method and evaluated with the log-rank test. The prognostic significance was assessed by univariate and multivariate analyses. RESULTS: There were 93 patients treated with surgery and 69 patients treated with radiotherapy. A cutoff of 5 for the SUV for the primary tumor showed the best discriminative value. The SUV for the primary tumor was a significant predictor of OS (P = .02) in both groups. Low SUVs ( 5.0; surgery group, P = .02; radiotherapy group, P = .0005). Low SUVs ( 5.0; stage I or II, P = .02; stage IIIa or IIIb, P = .004). However, using the same cutoff point of 5, the SUV for regional lymph nodes was not a significant indicator for DFS (P = .19), LRC (P = .97), or DMFS (P = .17). The multivariate analysis showed that the SUV for the primary tumor was a significant prognostic factor for OS (P = .03) and DFS (P = .001). CONCLUSION: The SUV of the primary tumor was the strongest prognostic factor among the patients treated by curative surgery or radiotherapy.     

Preoperative 18[F]-fluorodeoxyglucose positron emission tomography/computed tomography predicts early recurrence after pancreatic cancer resection

Background  

An important step in deciding the treatment strategy for pancreatic cancer is to preoperatively predict the possibility of early recurrence. We reviewed whether 18[F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) before pancreatic cancer resection could predict tumor recurrence in the early postoperative period.     

Role of 2-[18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the early assessment of response to chemotherapy in metastatic breast cancer patients

We investigated the role of 2-[18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the early evaluation of response to chemotherapy in metastatic breast cancer patients. Breast cancer patients who received an epirubicin/paclitaxel--containing regimen as first-line treatment for metastatic disease were included in this study. A PET study was performed within 1 week before the start of treatment, at day 8 after the first course, and at the end of the planned program of chemotherapy. Tumor response was determined clinically and radiographically every 2 courses of treatment. Thirteen patients with metastatic breast cancer who were referred for treatment protocols with gemcitabine/epirubicin/paclitaxel or epirubicin/paclitaxel chemotherapy regimens were included in this study. All metastatic sites were easily visualized on the baseline FDG-PET images, obtained 50 to 60 minutes after tracer injection. Nine patients who completed the planned courses of chemotherapy and the FDG-PET studies were available for analysis. In the six patients who achieved a response to treatment, median glucose standard uptake value (SUV) (semiquantitative analysis) was 7.65 (range, 3.4-12.3) at baseline, 5.7 (range, 2.8-7.6) at day 8 after the first course, and 1.2 (range, 0.99-1.3) at the end of the 6 planned courses of chemotherapy. Three patients who obtained a stable disease as best response had no significant decrease in tumor glucose SUV compared to baseline levels. Qualitative visual analysis in the six responding patients showed a decrease in delineation of tumor mass from background activity soon after the first course, while the nonresponding patients had no significant modification from basal levels. Semiquantitative FDG-PET scanning of metastatic breast cancer sites showed a rapid and significant decrease in tumor glucose metabolism soon after the first course of treatment in patients who achieved a response to first-line chemotherapy. On the contrary, no significant decrease was observed in nonresponding patients.     

Using positron emission tomography with [(18)F]FDG to predict tumor behavior in experimental colorectal cancer

This study investigates the relationship between FDG uptake as determined by positron emission tomography (PET) imaging and rates of tumor growth, cellular GLUT1 transporter density, and the activities of hexokinase and glucose-6-phosphatase in a solid tumor implant model. Five different human colorectal xenografts of different growth properties were implanted in athymic rats and evaluated by dynamic (18)F-FDG-PET. The phosphorylating and dephosphorylating activities of the key glycolytic enzymes, hexokinase and glucose-6-phosphatase, were measured in these tumor types by spectrophotometric assays and the expression of GLUT1 glucose transporter protein was determined by immunohistochemistry. Correlations among FDG accumulation, hexokinase activity, and tumor doubling time are reported in these colon xenografts. The results indicate that the activity of tumor hexokinase may be a marker of tumor growth rate that can be determined by (18)F-FDG-PET imaging. PET scanning may not only be a useful tool for staging patients for extent of disease, but may provide important prognostic information concerning the proliferative rates of malignancies.     

Correlation among [18F]fluorodeoxyglucose positron emission tomography/computed tomography, cancer antigen 27.29, and circulating tumor cell testing in metastatic breast cancer

Background: Tumor marker cancer antigen (CA) 27.29 and combined [18F]-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) scans are used to follow up response to treatment and disease progression in patients with metastatic breast cancer (MBC). Recently, circulating tumor cell testing (CTC) has been used in this context. It is not known if 1 of the 3 tests can be a surrogate for another. Patients and Methods: We analyzed a database of 35 patients with MBC. There were 173 time points (>/= 6 weeks apart) when >/= 2 of these tests were performed. Correlation among all the 3 tests was statistically analyzed. Results: Results of PET/CT scans were compared with CA 27.29 at 163 time points. There was a statistically significant correlation between both groups (P = .02); however, sensitivity of CA 27.29 to detect metastatic disease observed on PET/CT scan was 59%. The results of PET/CT scans were compared with CTC at 93 events, where there was a statistically significant correlation between both groups (P = .0002); however, sensitivity of CTC to detect metastatic disease shown on PET/CT scans was 55%. Cancer antigen 27.29 results were also compared to CTC at 100 events, where there was a statistically significant correlation between both groups (P = .0002). However, only 64% of patients with high CA 27.29 had abnormal CTC. Conclusion: Our data shows correlation among PET/CT scan, CA 27.29, and CTC. However, both CA 27.29 and CTC had poor sensitivity and negative predictive value to detect metastatic disease observed on PET/CT scan. Normal CA 27.29 testing or CTC has to be interpreted cautiously in patients with MBC.     

Positron emission tomography using [(18)F]-fluorodeoxy-D-glucose to predict the pathologic response of breast cancer to primary chemotherapy.

PURPOSE: To determine whether [(18)F]-fluorodeoxy-D-glucose ([(18)F]-FDG) positron emission tomography (PET) can predict the pathologic response of primary and metastatic breast cancer to chemotherapy. PATIENTS AND METHODS: Thirty patients with noninflammatory, large (> 3 cm), or locally advanced breast cancers received eight doses of primary chemotherapy. Dynamic PET imaging was performed immediately before the first, second, and fifth doses and after the last dose of treatment. Primary tumors and involved axillary lymph nodes were identified, and the [(18)F]-FDG uptake values were calculated (expressed as semiquantitative dose uptake ratio [DUR] and influx constant [K]). Pathologic response was determined after chemotherapy by evaluation of surgical resection specimens. RESULTS: Thirty-one primary breast lesions were identified. The mean pretreatment DUR values of the eight lesions that achieved a complete microscopic pathologic response were significantly (P =.037) higher than those from less responsive lesions. The mean reduction in DUR after the first pulse of chemotherapy was significantly greater in lesions that achieved a partial (P =.013), complete macroscopic (P =.003), or complete microscopic (P =.001) pathologic response. PET after a single pulse of chemotherapy was able to predict complete pathologic response with a sensitivity of 90% and a specificity of 74%. Eleven patients had pathologic evidence of lymph node metastases. Mean pretreatment DUR values in the metastatic lesions that responded did not differ significantly from those that failed to respond (P =.076). However, mean pretreatment K values were significantly higher in ultimately responsive cancers (P =.037). The mean change in DUR and K after the first pulse of chemotherapy was significantly greater in responding lesions (DUR, P =.038; K, P =.012). CONCLUSION: [(18)F]-FDG PET imaging of primary and metastatic breast cancer after a single pulse of chemotherapy may be of value in the prediction of pathologic treatment response.     

Early prediction of response to first-line chemotherapy by sequential [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography in patients with advanced colorectal cancer

Background: To evaluate [¹⁸F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), for early evaluation of response to palliative chemotherapy and for prediction of long-term outcome, in patients with metastatic colorectal cancer (mCRC).Patients and methods: In a randomized trial, patients with mCRC received irinotecan-based combination chemotherapy. FDG–PET was carried out before treatment and after two cycles in 51 patients at two centers. Visual changes in tumor FDG uptake and changes measured semi-automatically, as standard uptake values (SUVs), were compared with radiological response after four and eight cycles.Results: The mean baseline SUV for all tumor lesions per patient was higher in nonresponders than in responders (mean 7.4 versus 5.6, P = 0.02). There was a strong correlation between metabolic response (changes in SUV) and objective response (r = 0.57, P = 0.00001), with a sensitivity of 77% and a specificity of 76%. There was no significant correlation between metabolic response and time to progression (P = 0.5) or overall survival (P = 0.1).Conclusions: Although metabolic response assessed by FDG–PET reflects radiological tumor volume changes, the sensitivity and specificity are too low to support the routine use of PET in mCRC. Furthermore, PET failed to reflect long-term outcome and can, thus, not be used as surrogate end point for hard endpoint benefit.     

Posttherapy [18F] fluorodeoxyglucose positron emission tomography in carcinoma of the cervix: response and outcome.

PURPOSE: The aim of this study was to evaluate response to therapy using posttherapy molecular imaging with [(18)F] fluorodeoxyglucose (FDG), and to compare the response with patient outcome. PATIENTS AND METHODS: This was a retrospective medical record review of 152 patients with carcinoma of the cervix. All patients underwent a pre- and posttreatment whole-body positron emission tomography (PET) imaging scan with FDG. Patients were treated with external irradiation and intracavitary brachytherapy, and most received concurrent weekly cisplatin. Posttherapy whole-body FDG-PET was performed 1 to 12 months (mean, 3 months) after completion of treatment. RESULTS: The posttherapy PET did not show any abnormal FDG uptake in 114 patients, and their 5-year cause-specific survival estimate was 80%. There was persistent (in the irradiated region) abnormal FDG uptake in the cervix or lymph nodes in 20 patients. Their 5-year cause-specific survival estimate was 32%. New anatomic sites (in unirradiated regions) of abnormal FDG uptake were present in 18 patients, and none were alive at 5 years. A Cox proportional hazards model of survival outcome indicated that any abnormal posttherapy FDG uptake (persistent or new) was the most significant prognostic factor for developing metastatic disease and death from cervical cancer when compared with pretreatment- and treatment-related prognostic factors (P <.0001). CONCLUSION: Posttherapy abnormal FDG uptake (persistent or new) as detected by whole-body PET measures tumor response and might be predictive of tumor recurrence and death from cervical cancer. Prospective validation of these results is warranted.     

Thyroid metastasis from colorectal cancer: role of [18F]-fluoro-2-deoxy-D-glucose positron emission tomography

We present a patient with colon carcinoma metastatic to the thyroid. Review of the literature reveals only a few reports of metastatic colorectal carcinoma to the thyroid. Metastatic tumors of the thyroid are no longer considered rare. Unfortunately, they often remain undetected because only a small minority of patients present with a mass lesion or enlargement of the gland. This is further evidenced by the fact that most reports come from autopsy series. Establishing this diagnosis is important because metastatic deposits in the thyroid can sometimes cause respiratory compromise as well as thyrotoxicosis.     

18F-FDG PET对非小细胞肺癌预后预测价值的研究进展

目的:探讨18F-FDG PET对非小细胞肺癌预后的研究进展,指导临床中PET的应用.方法:应用计算机在PUBMED数据库检索2002～2007年有关18F-FDG PET对非小细胞肺癌预后的文章,并限定文献语种为英文,检索词fluorodeoxyglucose (FDG)、positron emmition tomography (PET)和non-small cell lung cancer和prognosis.同时,计算机检索中国期刊全文数据库2002～2007年的相关文章,检索词为PET和肺肿瘤,限定文章语言种类为中文.对选择的资料进行初审,选取和PDGPET以及与其非小细胞肺癌预后相关的文献,然后查找全文.排除标准:1)重复研究;2)个案报道.共收集到相关文献59篇,排除重复或类似的同一研究,最终纳入30篇符合标准的文献.结果:大部分研究证明,肺癌原发灶的18F-氟脱氧葡萄糖(18F-FDG)标准摄取值(standardized uptake value, SUV)与患者的预后相关,治疗前后SUV值高的患者预后相对SUV值低的患者对放化疗敏感性差;进一步的研究显示,其复发的概率相对高,预后较差.但是放疗前后SUV变化能否作为独立的预后因素尚存在争议.结论:PET在非小细胞肺癌的预后判断方面有重要意义.不仅可以广泛用于放化疗疗效评价,也可用于预测肺癌治疗后复发以及对患者生存期的预测.     

3'-deoxy-3'-[18F]fluorothymidine positron emission tomography is a sensitive method for imaging the response of BRAF-dependent tumors to MEK inhibition

Activating mutations of BRAF occur in approximately 7% of all human tumors and in the majority of melanomas. These tumors are very sensitive to pharmacologic inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), which causes loss of D-cyclin expression, hypophosphorylation of Rb, and G(1) arrest. Growth arrest is followed by differentiation or senescence and, in a subset of BRAF mutant tumors, by apoptosis. The former effects result in so-called "stable disease" and, in patients with cancer, can be difficult to distinguish from indolent tumor growth. The profound G(1) arrest induced by MEK inhibition in BRAF mutant tumors is associated with a marked decline in thymidine uptake and is therefore potentially detectable in vivo by noninvasive 3'-deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT) positron emission tomography (PET) imaging. In SKMEL-28 tumor xenografts, MEK inhibition completely inhibited tumor growth and induced differentiation with only modest tumor regression. MEK inhibition also resulted in a rapid decline in the [(18)F]FLT signal in V600E BRAF mutant SKMEL-28 xenografts but not in BRAF wild-type BT-474 xenografts. The data suggest that [(18)F]FLT PET can effectively image induction of G(1) arrest by MEK inhibitors in mutant BRAF tumors and may be a useful noninvasive method for assessing the early biological response to this class of drugs.     

18F]fluoro-deoxy-glucose positron emission tomography ([18F]FDG-PET) voxel intensity-based intensity-modulated radiation therapy (IMRT) for head and neck cancer.

BACKGROUND AND PURPOSE: Focused dose escalation may improve local control in head and neck cancer. Planning results of [(18)F]fluoro-deoxy-glucose positron emission tomography ([(18)F]FDG-PET) voxel intensity-based intensity-modulated radiation therapy (IMRT) were compared with those of PET contour-based IMRT. PATIENTS AND METHODS: PET contour-based IMRT aims to deliver a homogeneous boost dose to a PET-based subvolume of the planning target volume (PTV), called PTV(PET). The present PET voxel intensity-based planning study aims to prescribe the boost dose directly as a function of PET voxel intensity values, while leaving the dose distribution outside the PTV unchanged. Two escalation steps (2.5 and 3 Gy/fraction) were performed for 15 patients. RESULTS: PTV(PET) was irradiated with a homogeneous dose in the contour-based approach. In the voxel intensity-based approach, one or more sharp dose peaks were created inside the PTV, following the distribution of PET voxel intensity values. CONCLUSIONS: While PET voxel intensity-based IMRT had a large effect on the dose distribution within the PTV, only small effects were observed on the dose distribution outside this PTV and on the dose delivered to the organs at risk. Therefore both methods are alternatives for boosting subvolumes inside a selected PTV.     

3'-deoxy-3'-[18F]fluorothymidine as a new marker for monitoring tumor response to antiproliferative therapy in vivo with positron emission tomography

3'-Deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT) has been proposed as a new marker for imaging tumor proliferation by positron emission tomography (PET). The uptake of [(18)F]FLT is regulated by cytosolic S-phase-specific thymidine kinase 1 (TK1). In this article, we have investigated the use of [(18)F]FLT to monitor the response of tumors to antiproliferative treatment in vivo. C3H/Hej mice bearing the radiation-induced fibrosarcoma 1 tumor were treated with 5-fluorouracil (5-FU; 165 mg/kg i.p.). Changes in tumor volume and biodistribution of [(18)F]FLT and 2-[(18)F]fluoro-2-deoxy-D-glucose ([(18)F]FDG) were measured in three groups of mice (n = 8-12/group): (a) untreated controls; (b) 24 h after 5-FU; and (c) 48 h after 5-FU. In addition, dynamic [(18)F]FLT-PET imaging was performed on a small animal scanner for 60 min. The metabolism of [(18)F]FLT in tumor, plasma, liver, and urine was determined chromatographically. Proliferation was determined by staining histological sections for proliferating cell nuclear antigen (PCNA). Tumor levels of TK1 protein and cofactor (ATP) were determined by Western blotting and bioluminescence, respectively. Tumor [(18)F]FLT uptake decreased after 5-FU treatment (47.8 +/- 7.0 and 27.1 +/- 3.7% for groups b and c, respectively, compared with group a; P < 0.001). The drug-induced reduction in tumor [(18)F]FLT uptake was significantly more pronounced than that of [(18)F]FDG. The PET image data confirmed lower tumor [(18)F]FLT retention in group c compared with group a, despite a trend toward higher radiotracer delivery for group c. Other than phosphorylation in tumors, [(18)F]FLT was found to be metabolically stable in vivo. The decrease in tumor [(18)F]FLT uptake correlated with the PCNA-labeling index (r = 0.71, P = 0.031) and tumor volume changes after 5-FU treatment (r = 0.58, P = 0.001). In this model system, the decrease in [(18)F]FLT uptake could be explained by changes in catalytic activity but not translation of TK1 protein. Compared with group a, TK1 levels were lower in group b (78.2 +/- 5.2%) but higher in group c (141.3 +/- 9.1%, P < 0.001). In contrast, a stepwise decrease in ATP levels was observed from group a to b to c (P < 0.001). In conclusion, we have demonstrated the ability to measure tumor response to antiproliferative treatment with [(18)F]FLT and PET. In our model system, the radiotracer uptake was correlated with PCNA-labeling index. The decrease in [(18)F]FLT uptake after 5-FU was more pronounced than that of [(18)F]FDG. [(18)F]FLT is, therefore, a promising marker for monitoring antiproliferative drug activity in oncology that warrants additional testing.     

Analysis and reproducibility of 3'-Deoxy-3'-[18F]fluorothymidine positron emission tomography imaging in patients with non-small cell lung cancer

PURPOSE: Imaging tumor proliferation with 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) and positron emission tomography is being developed with the goal of monitoring antineoplastic therapy. This study assessed the methods to measure FLT retention in patients with non-small cell lung cancer (NSCLC) to measure the reproducibility of this approach. EXPERIMENTAL DESIGN: Nine patients with NSCLC who were untreated or had progressed after previous therapy were imaged twice using FLT and positron emission tomography within 2 to 7 days. Reproducibility (that is, error) was measured as the percent difference between the two patient scans. Dynamic imaging was obtained during the first 60 min after injection. Activity in the blood was assessed from aortic images and the fraction of unmetabolized FLT was measured. Regions of interest were drawn on the plane with the highest activity and the adjacent planes to measure standardized uptake value (SUV(mean)) and kinetic variables of FLT flux. RESULTS: We found that the SUV(mean) obtained from 30 to 60 min had a mean error of 3.6% (range, 0.6-6.9%; SD, 2.3%) and the first and second scans were highly correlated (r(2) = 0.99; P < 0.0001). Using shorter imaging times from 25 to 30 min or from 55 to 60 min postinjection also resulted in small error rates; SUV(mean) mean errors were 8.4% and 5.7%, respectively. Compartmental and graphical kinetic analyses were also fairly reproducible (r(2) = 0.59; P = 0.0152 and r(2) = 0.58; P = 0.0175 respectively). CONCLUSION: FLT imaging of patients with NSCLC was quite reproducible with a worst case SUV(mean) error of 21% when using a short imaging time.