Semiquantitative analysis of C-11 methionine PET may distinguish brain tumor recurrence from radiation necrosis even in small lesions (original) (raw)
Related papers
BMC Cancer
Background: On conventional diagnostic imaging, the features of radiation necrosis (RN) are similar to those of local recurrence (LR) of brain metastases (BM). 11 C-methionine positron emission tomography (MET-PET) is reportedly useful for making a differential diagnosis between LR and RN. In this prospective study, we aimed to investigate the diagnostic performance of MET-PET and the long-term results of subsequent patient management. Methods: The eligible subjects had enlarging contrast-enhanced lesions (>1 cm) on MR imaging after any form of radiotherapy for BM, suggesting LR or RN. However, it was difficult to differentiate LR from RN in these cases. From August 2013 to February 2017, MET-PET was performed for 37 lesions in 32 eligible patients. Tracer accumulation in the regions of interest was analysed as the standardised uptake value (SUV) and maximal lesion SUV/maximal normal tissue SUV ratios (LNR) were calculated. The cutoff value for LNR was provisionally set at 1.40. Salvage treatment strategies determined based on MET-PET diagnosis and treatment results were investigated. The diagnostic accuracy of MET-PET was evaluated by receiver operating characteristic (ROC) curve analysis. Results: The median interval from primary radiotherapy to MET-PET was 19 months and radiotherapy had been performed twice or more for 13 lesions. The MET-PET diagnoses were LR in 19 and RN in 18 lesions. The mean values and standard deviation of LNRs for each diagnostic category were 1.70 ± 0.30 and 1.09 ± 0.25, respectively. At the median follow-up time of 18 months, final diagnoses were confirmed histologically for 17 lesions and clinically for 20 lesions. ROC curve analysis indicated the optimal LNR cutoff value to be 1.40 (area under the curve: 0.84), and the sensitivity and specificity were 0.82 and 0.75, respectively. The median survival times of patient groups with LR and RN based on MET-PET diagnosis were 14.8 months and 35.1 months, respectively (P = 0.035, log-rank test). Conclusions: MET-PET showed apparently reliable diagnostic performance for distinguishing between LR and RN. The provisional LNR cutoff value of 1.4 in our institution was found to be appropriate. Limitations of diagnostic accuracy should be recognised in cases with LNR close to this cutoff value.
International Congress Series, 2004
Objectives: The purpose of the present study was to determine whether PET with 11C-methionine (MET) is valuable in distinguishing recurrent tumor from radiation necrosis. Methods: Twenty-one patients (27 lesions) with previously treated 10 primary or 11 metastatic brain tumor who presented focally enhanced mass lesion on postcontrast magnetic resonance imaging (MRI) images were studied with MET-PET. Uptake of MET was
PET imaging for differentiating recurrent brain tumor from radiation necrosis
Radiologic clinics of North America, 2005
The exact incidence of true radiation necrosis is largely unknown. It is probably much less frequent than indicated by MR or CT findings. Differentiating radiation necrosis from recurrent tumor is a diagnostic challenge, however, and has important implications for the patient's management. Even though the first results were published 20 years ago, the total number of case studies using FDG-PET in this indication remains limited. Several reports are also hampered by methodologic limitations. The technique has been largely criticized, notably in articles that themselves were not completely free of methodological flaws. Overall however, FDG-PET seems to be a valuable clinical tool. As a general rule, suspicious lesions on MR imaging that show increased FDG uptake (ie, uptake equal to or great than that in normal cortex) are likely to represent tumor recurrence. Sensitivity is an issue, especially but not exclusively with low-grade gliomas. Although false-positive results may occur,...
PET versus SPECT in distinguishing radiation necrosis from tumor recurrence in the brain
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1995
Two cases of postsurgical brain tumor evaluation in which MRI was inconclusive are discussed. Functional imaging techniques, such as FDG-PET and 201TI SPECT, were used in both cases for distinguishing radiation necrosis from tumor recurrence. These methods proved to be complimentary. For Patient 1, FDG-PET showed more limitations compared to 201TI SPECT. FDG-PET results on the other hand, were consistent with the final diagnosis and the SPECT image was false positive for tumor recurrence in Patient 2.
Clinical Nuclear Medicine, 2012
With the availability of multiple positron emission tomography (PET) tracers for neurooncology, there is a need to define the appropriate tracer in a given clinical setting, and it is in this regard that we undertook this study to directly compare F-18 flurodeoxyglucose (FDG) PET and C-11 methionine (MET) PET for the evaluation of recurrence in primary brain tumors. Patients and Methods: Thirty-seven patients with a history of treated primary brain tumors referred for evaluation of recurrent disease were initially included in the study. Two patients had to be excluded because of insufficient follow-up. There were 23 males and 12 females, mean age: 33.7 Ϯ 16.4 years; range: 5 to 65 years. All patients underwent the MET and FDG study on the same day. Visual image interpretation was performed independently by 2 PET physicians for each tracer using the plain PET and fused PET/CT images; the FDG images were evaluated first. Images were analyzed semiquantitatively using tumor to normal contralateral cortex ratios (T/N). Each patient was followed up for a minimum of 18 months. Imaging results were compared with histopathology on tumor excision or biopsy in 14 patients and with clinical follow-up and MRI/MRS at the end of 18 months in 21 patients. Results: The final diagnosis was tumor recurrence in 24 patients and no recurrence/stable disease in 11 patients. On FDG, findings in 15/35 (42%) were suggestive of recurrent tumors. On MET, findings in 24/34 (70.5%) cases were suggestive of recurrent tumors. Spatially separated secondary lesions including intraventricular deposits were clearly delineated in 5 cases, 3 were glioblastoma multiforme (GBM) and 2 were anaplastic astrocytomas. One of the secondary lesions was missed on FDG PET. Using a cutoff for T/N ratio on FDG of Ͼ0.75 to differentiate recurrence from no recurrence, sensitivity of FDG was 81.2% (confidence interval ͓CI͔ ϭ 54.4%-96%), whereas specificity was 88.9% (CI ϭ 51.8%-99.7%). Area under the curve was 0.819 (CI ϭ 0.615-0.943), P ϭ 0.0003. Using a cutoff for T/N ratio of Ͼ1.9 to differentiate recurrence from no recurrence, sensitivity of MET was 94.7% (CI ϭ 74.0%-99.9%), whereas specificity was 88.89% (CI ϭ 51.8%-99.7%). Area under the curve was 0.942 (CI ϭ 0.785-0.995), P Ͻ 0.0001. Interobserver agreement, coefficient, for MET was 0.93, suggesting good interobserver agreement, whereas for FDG, it was fair (0.23). Conclusions: MET should be the radiotracer of choice in the evaluation of recurrence of primary brain tumors because the sensitivity for detection and delineation of the possible recurrent tumor, as well as secondary deposits, is higher with MET. MET-PET is an easier technique to interpret, irrespective of the glioma grade, with less interobserver variability and straightforward localization of tumorous accumulation.
Clinical Neurology and Neurosurgery, 2010
Purpose: The authors analyzed the characteristics of perfusion magnetic resonance imaging (MRI), 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and 11 C-methionine (MET) PET to compare the efficacies of these modalities in making the distinction between radiation necrosis and tumor recurrence of high-grade glioma. Patients and methods: Ten patients were evaluated with dynamic susceptibility contrast perfusion MRI, 11 C-MET PET and 18 F-FDG PET to visualize gadolinium-enhanced lesions during the post-radiation followup period. In the perfusion MRI, four regions of interest (ROIs) were identified and average values were calculated. A reference ROI of the same size was defined in the contralateral white matter to obtain the relative cerebral blood volume (rCBV). After coregistering the PET images with the MRI, we measured the maximum uptake values of the lesion and of the contralateral cerebral white matter as reference area to calculate the L max /R max ratio. Results: The rCBV was higher in the recurrence group than in the necrosis group (p = 0.010). There was no difference between groups in terms of the L max /R max ratio as derived from the 18 F-FDG and 11 C-MET PET. Conclusion: A quantitative rCBV as calculated from a perfusion MRI scan might be superior to the L max /R max ratio as derived from 18 F-FDG and 11 C-MET PET in order to distinguish a recurrence of high-grade glioma from radiation necrosis.
ACT-07 Clinical Trials of 11C-Methionine PET for brain tumors
Neuro-Oncology Advances, 2020
Background: Although 11C-Methionine (MET) PET has widely used, 11C-MET tracer has not been approved in Japan. We conducted multi-center prospective clinical trials using MET for drug approval in diagnosis of brain tumors[Methods] Two trials using 11C-MET PET were performed in Hokkaido University, Osaka University and Fukushima Medical University; 1) Diagnostic accuracy in differentiating tumor recurrence from radiation injury after radiotherapy in brain tumors, 2) The diagnostic efficacy in newly-diagnosed gliomas. 1) The patients with suspected brain tumor recurrence underwent MET and 18F-Fluorodeoxyglucose (FDG) PET. When the target lesion showed MET and/or FDG uptake, the patients underwent target resection for pathological confirmation. Positive prediction values of each tracer uptake were assessed as primary outcome measure, and the sensitivities and specificities of each PET exams were also assessed. 2) The patients with suspected gliomas underwent MET PET. Tissue samplings we...
Objective: [ 11 C] methionine (MET) positron-emission tomography (PET) is a useful diagnostic and therapeutic tool in neuro-oncology. The aim of this study was to evaluate the relationship between MET uptake and the histopathological grade in both primary brain tumours and brain metastases. A secondary goal was to assess the relationship between MET uptake and patients' survival after surgery. Methods: We reviewed a consecutive series of 43 PET studies performed at our institution. Out of the 43 patients studied, 35 harboured primary brain tumours (3 grade I, 12 grade II, 7 grade III and 13 grade IV) and 8 patients had brain metastases. We measured the tumour/cortex ratio (T/C ratio) on each PET study and we investigated the correlations among the tracer uptake, tumour grade, tumour type, MRI parameters and outcome. Results: The mean T/C ratio was 1.8 ± 0.9 for benign lesions and low grade gliomas (grade I and II) and 2.7 ± 1 for high grade gliomas (grade III and IV). In brain metastases it was 2.5 ± 0.7, with a significant difference in MET uptake between low and high grades gliomas (P = 0.03). There was no statistically significant difference among all different histologic types. We found that both contrast enhancement and perfusion studies correlate with MET uptake in brain tumours. Moreover, in Kaplan–Meier curves, the T/C ratio adversely affects long term survival in patients with brain tumours (P = 0.01). Conclusions: MET PET appears to be useful in diagnosis and evaluation of potential malignancy in brain tumours. MET uptake is also related with the overall survival in patients with brain tumours. Nevertheless, further studies are needed in order to define its possible clinical implications in identifying patients at high risk of tumour progression or resistance to therapy.