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Abstract Background Glioblastoma (GBM) is the most common and aggressive primary brain cancer. The treatment of GBM consists of a combination of surgery and subsequent oncological therapy, i.e., radiotherapy, chemotherapy, or their combination. If postoperative oncological therapy involves irradiation, magnetic resonance imaging (MRI) is used for radiotherapy treatment planning. Unfortunately, in some cases, a very early worsening (progression) or return (recurrence) of the disease is observed several weeks after the surgery and is called rapid early progression (REP). Radiotherapy planning is currently based on MRI for target volumes definitions in many radiotherapy facilities. However, patients with REP may benefit from targeting radiotherapy with other imaging modalities. The purpose of the presented clinical trial is to evaluate the utility of 11C-methionine in optimizing radiotherapy for glioblastoma patients with REP. Methods This study is a nonrandomized, open-label, parallel-setting, prospective, monocentric clinical trial. The main aim of this study was to refine the diagnosis in patients with GBM with REP and to optimize subsequent radiotherapy planning. Glioblastoma patients who develop REP within approximately 6 weeks after surgery will undergo 11C-methionine positron emission tomography (PET/CT) examinations. Target volumes for radiotherapy are defined using both standard planning T1-weighted contrast-enhanced MRI and PET/CT. The primary outcome is progression-free survival defined using RANO criteria and compared to a historical cohort with REP treated without PET/CT optimization of radiotherapy. Discussion PET is one of the most modern methods of molecular imaging. 11C-Methionine is an example of a radiolabelled (carbon 11) amino acid commonly used in the diagnosis of brain tumors and in the evaluation of response to treatment. Optimized radiotherapy may also have the potential to cover those regions with a high risk of subsequent progression, which would not be identified using standard-of-care MRI for radiotherapy planning. This is one of the first study focused on radiotherapy optimization for subgroup of patinets with REP. Trial Registration NCT05608395, registered on 8.11.2022 in clinicaltrials.gov; EudraCT Number: 2020–000640-64, registered on 26.5.2020 in clinicaltrialsregister.eu. Protocol ID: MOU-2020–01, version 3.2, date 18.09.2020.

Objective: 11C-Methionine positron emission tomography (MET-PET) is used for stereotactic radiotherapy planning in meningioma patients. The role of MET-PET during subsequent follow-up (FU) is unclear. We analyzed the uptake of 11C-Methionine before and after stereotactic radiotherapy (SRT) in patients with a complex meningioma and investigated if there was a difference between patients with progressive disease (PD) and stable disease (SD) during FU. Methods: This retrospective study investigates 62 MET-PETs in 29 complex meningioma patients. Standardized uptake value (SUV)max and SUVpeak tumor-to-normal ratios (T/N-ratios) were calculated, comparing the tumor region with both the mirroring intracranial area and the right frontal gray matter. The difference in 11C-Methionine uptake pre- and post-SRT was analyzed, as well as the change in uptake between PD or SD. Results: Median (IQR) FU duration was 67 months (50.5–91.0). The uptake of 11C-Methionine in meningiomas remained increased after SRT. Neither a statistically significant difference between MET-PETs before and after SRT was encountered, nor a significant difference in one of the four T/N-ratios between patients with SD versus PD with median (IQR) SUVmax T/NR front 2.65 (2.13–3.68) vs 2.97 (1.55–3.54) [p = 0.66]; SUVmax T/Nmirror 2.92 (2.19–3.71) vs 2.95 (1.74–3.60) [p = 0.61]; SUVpeak T/NR front 2.35 (1.64–3.40) vs 2.25 (1.44–3.74) [p = 0.80]; SUVpeak T/Nmirror 2.38 (1.91–3.36) vs 2.35 (1.56–3.72) [p = 0.95]. Conclusions: Our data do not support use of MET-PET during FU of complex intracranial meningiomas after SRT. MET-PET could not differentiate between progressive or stable disease. [ABSTRACT FROM AUTHOR]

Positron emission tomography combined with computed tomography (PET/CT) is currently the standard imaging method in neuro-oncology for gliomas and metastatic lesions. There is much less experience with the use of PET/CT in meningioma, the most common primary tumor of the central nervous system, and there are some differences in how results are interpreted. The aim of the present work was to assess the potential for and features of the use of PET/CT to determine the degree of malignancy of meningioma, its prevalence, responses to radiotherapy, and diagnosis of relapse and/or post-radiation changes based on our own clinical experience and review of the literature. The study included 70 patients with 77 meningiomas who underwent 11C-methionine PET/CT. Mean age at investigation was 57.4 years (range 19–86 years). The main parameter evaluated, the tumor/normal ratio (T/N) of 11C-methionine (11C-MET) in tumors, averaged 3.13 (1.00–10.66). Meningiomas had high 11C-MET T/N, with values of >1.5 in 89.6% of cases. In histologically verified malignancy grade 1, 2, and 3 meningiomas (WHO scale), median T/N values were 4.06 [3.04; 4.57], 2.32 [2.12; 3.69], and 4.29 [2.60; 5.10] respectively, with no significant between-group differences. At the same time, non-growing or slowly growing histologically unverified meningiomas, i.e., incidentally discovered, had significantly lower 11C-MET T/N than grade 1 and 3 meningiomas. There was no significant difference in T/N between irradiated meningiomas with controls for tumor growth (3.81 [2.97, 3.98]) and relapse (3.62 [2.60, 4.30]). Comparison of irradiated and non-irradiated grade 1, 2, and 3 meningiomas, as well as the combined group of grade 1–3 tumors, revealed no significant differences in 11C-MET T/N. The use of PET/CT for meningiomas has a number of important characteristics. Meningiomas had high 11C-MET T/N. Our data indicate that 11C-MET PET/CT does not distinguish between meningiomas with different degrees of malignancy, i.e., WHO grades 1, 2, and 3. 11C-MET T/N in meningiomas remains stably high or shows a slight decrease in cases with effective radiotherapy and long-term local control. Comparison of growing and non-growing meningiomas revealed no significant differences in 11C-MET T/N between irradiated and non-irradiated tumors. [ABSTRACT FROM AUTHOR]

Glioblastoma (GB) is characterized by a high degree of heterogeneity in its development in space and time, which is due to genomic instability, high growth rates in individual regions, and heterogeneous neovascularization. The molecular genetic features of GB play an important role in the prognosis of the disease, which is reflected in the new (2021) WHO classification of central nervous system tumors. The aim of the present work was to compare MRI data on blood flow and diffusion parameters and PET/CT data on tumor tissue metabolism with the genetic profiles of GB. The study included 40 patients (age 55 ± 12 years, male:female = 31:9) with first diagnoses of GB who underwent evaluation of MRI parameters (apparent diffusion coefficient (ADC), cerebral blood flow velocity (CBF), ASL perfusion data) and PET/CT to acquire the methionine (MET) uptake index. All these volumetric profiles (VOI – 1 cm3) were automatically transferred using software (PMOD) to all map images and compared with each other; a total of nine parameters were obtained: METmax, METcbf, METadc, ADCmin, ADCmet, ADCcbf, CBFmax, CBFmet, and CBFadc. Comparative and correlation analysis of parameters was carried out, both in the overall GB group and separately in genetically different subgroups (MGMT+/– and EGFR+/–) and in groups defined by Ki67 level. The study showed that the locations of zones with high values for blood flow, cell density, and amino acid metabolism coincided in only 45% of cases, demonstrating the occurrence of differences in the structure and functional activity of GB areas. Data on the relationship between methylation of the MGMT gene promoter and ADC (ADCmin > 1.01 (10–3 mm2/sec), Se = 78%, Sp = 74%, AUC = 0.77) confirmed results reported by other authors showing that this genetic subtype of GB has lower requirements for the construction of new membranes, due to inhibition of the mechanisms if the DNA repair system. Detection of amplification of the EGFR gene in our cohort was associated with a significant increase in MET metabolism (METmax > 3.29, Se = 88%, Sp = 70%, AUC = 0.82) and correlated with a higher Ki67 index [Rs = –0.85], confirming the fact of an increase in the consumption of amino acids by GB cells for membrane synthesis. The correlations between the MET uptake index and ADC and the absence of such with CBF parameters confirm the relationship of methionine metabolism in gliomas with the processes of building new cell membranes and not with neovascularization. The phenomenon of heterogeneity in the structure of GB was confirmed on the basis of differences found in the locations of the zones in which the standard MRI and PET/CT parameters had their maximum values, as well as significant differences between them in groups of patients with GB with different molecular genetic profiles. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma (GBM) is the most common and aggressive primary brain cancer. The treatment of GBM consists of a combination of surgery and subsequent oncological therapy, i.e., radiotherapy, chemotherapy, or their combination. If postoperative oncological therapy involves irradiation, magnetic resonance imaging (MRI) is used for radiotherapy treatment planning. Unfortunately, in some cases, a very early worsening (progression) or return (recurrence) of the disease is observed several weeks after the surgery and is called rapid early progression (REP). Radiotherapy planning is currently based on MRI for target volumes definitions in many radiotherapy facilities. However, patients with REP may benefit from targeting radiotherapy with other imaging modalities. The purpose of the presented clinical trial is to evaluate the utility of 11C-methionine in optimizing radiotherapy for glioblastoma patients with REP. Methods: This study is a nonrandomized, open-label, parallel-setting, prospective, monocentric clinical trial. The main aim of this study was to refine the diagnosis in patients with GBM with REP and to optimize subsequent radiotherapy planning. Glioblastoma patients who develop REP within approximately 6 weeks after surgery will undergo 11C-methionine positron emission tomography (PET/CT) examinations. Target volumes for radiotherapy are defined using both standard planning T1-weighted contrast-enhanced MRI and PET/CT. The primary outcome is progression-free survival defined using RANO criteria and compared to a historical cohort with REP treated without PET/CT optimization of radiotherapy. Discussion: PET is one of the most modern methods of molecular imaging. 11C-Methionine is an example of a radiolabelled (carbon 11) amino acid commonly used in the diagnosis of brain tumors and in the evaluation of response to treatment. Optimized radiotherapy may also have the potential to cover those regions with a high risk of subsequent progression, which would not be identified using standard-of-care MRI for radiotherapy planning. This is one of the first study focused on radiotherapy optimization for subgroup of patinets with REP. Trial Registration: NCT05608395, registered on 8.11.2022 in clinicaltrials.gov; EudraCT Number: 2020–000640-64, registered on 26.5.2020 in clinicaltrialsregister.eu. Protocol ID: MOU-2020–01, version 3.2, date 18.09.2020. [ABSTRACT FROM AUTHOR]

Objective: To investigate differences in uptake regions between methyl-11C-L-methionine positron emission tomography (11C-MET PET) and gadolinium (Gd)-enhanced magnetic resonance imaging (MRI), and their impact on dose distribution, including changing of the threshold for tumor boundaries. Methods: Twenty consecutive patients with grade 3 or 4 glioma who had recurrence after postoperative radiotherapy (RT) between April 2016 and October 2017 were examined. The study was performed using simulation with the assumption that all patients received RT. The clinical target volume (CTV) was contoured using the Gd-enhanced region (CTV(Gd)), the tumor/normal tissue (T/N) ratios of 11C-MET PET of 1.3 and 2.0 (CTV (T/N 1.3), CTV (T/N 2.0)), and the PET-edge method (CTV(P-E)) for stereotactic RT planning. Differences among CTVs were evaluated. The brain dose at each CTV and the dose at each CTV defined by 11C-MET PET using MRI as the reference were evaluated. Results: The Jaccard index (JI) for concordance of CTV (Gd) with CTVs using 11C-MET PET was highest for CTV (T/N 2.0), with a value of 0.7. In a comparison of pixel values of MRI and PET, the correlation coefficient for cases with higher JI was significantly greater than that for lower JI cases (0.37 vs. 0.20, P = 0.007). D50% of the brain in RT planning using each CTV differed significantly (P = 0.03) and that using CTV (T/N 1.3) were higher than with use of CTV (Gd). V90% and V95% for each CTV differed in a simulation study for actual treatment using CTV (Gd) (P = 1.0 × 10–7 and 3.0 × 10–9, respectively) and those using CTV (T/N 1.3) and CTV (P-E) were lower than with CTV (Gd). Conclusions: The region of 11C-MET accumulation is not necessarily consistent with and larger than the Gd-enhanced region. A change of the tumor boundary using 11C-MET PET can cause significant changes in doses to the brain and the CTV. [ABSTRACT FROM AUTHOR]

Objective: To investigate the potential of whole-body digital 11C-methionine (MET) PET/CT imaging for simultaneous evaluation of thoracic cancer patients suspected of local recurrence (LR) after stereotactic radiosurgery (SRS) for brain metastasis. Methods: A total of 45 lung or breast cancer patients suspected of LR after SRS were investigated using brain and whole-body MET-PET/CT scans. We compared the tumor-to-normal ratio (TNR) and maximum standardized uptake values (SUVmax) between patients with LR and radiation necrosis (RN) and performed receiver operating characteristic (ROC) analyses. We also investigated associations among extracranial recurrence, intracranial recurrence, primary site, and initial treatment type. Results: A total of 44 LR and 14 RN lesions were analyzed. In the ROC analyses for differentiating LR from RN, TNR showed higher area under the curve (AUC) (0.82) than SUVmax (0.79), and the cutoff TNR value (2.12) was higher than current cutoff values of conventional PET systems. The whole-body scans detected extracranial recurrences in 31.1% of the patients. Recurrence rates were not significantly correlated with existence of intracranial recurrence or primary site, but patients who underwent non-surgical treatment (consisting of stage III/ IV patients according to the Union for International Cancer Control TNM classification or small-cell lung cancer patients) showed significantly higher recurrence than the surgically treated patients (68.8% vs. 10.3%, p = 0.0001). Conclusion: In digital MET-PET/CT imaging, TNR was a more useful parameter to differentiate LR from RN than SUVmax, and the cutoff value was higher than those with conventional PET systems. Additional whole-body scans could detect extracranial recurrence and would be especially useful for advanced thoracic cancer patients who underwent non-surgical treatment. [ABSTRACT FROM AUTHOR]

Purpose: Distinguishing between primary central nervous system lymphoma (PCNSL) and isocitrate dehydrogenase (IDH)-wildtype glioblastoma is important for therapeutic decision-making. This study aimed to compare the performance of 11C-methionine (MET) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for distinguishing between these two major malignant brain tumors. Methods: We retrospectively conducted qualitative and semiquantitative analyses of pre-treatment MET and FDG PET/computed tomography (CT) images of 22 patients with PCNSL and 64 patients with IDH-wildtype glioblastoma. For semiquantitative analysis, we calculated the tumor-to-normal tissue (T/N) ratio by dividing the maximum standardized uptake value (SUV) for the tumor (T) by the average SUV for the normal tissue (N). For performance evaluation, we employed receiver operating characteristic curve analysis and calculated the areas under the curve (AUC) values. Results: In the qualitative analysis, all PCNSLs and IDH-wildtype glioblastomas were MET-positive, while 95% and 84% of PCNSLs and IDH-wildtype glioblastomas, respectively, were FDG-positive. Eleven patients were excluded from the FDG PET/CT semiquantitative analysis because of hyperglycemia. There was no difference in MET T/N ratio between PCNSL and IDH-wildtype glioblastoma (p = 0.37). FDG T/N ratio was significantly higher in PCNSL than in IDH-wildtype glioblastoma (p < 0.001). The AUC value for distinguishing PCNSL from IDH-wildtype glioblastoma was significantly higher for the FDG T/N ratio (0.871) than for the MET T/N ratio (0.565) (p = 0.0027). Conclusion: MET PET could detect both PCNSL and IDH-wildtype glioblastoma, but unlike FDG PET, it could not distinguish between these two major malignant brain tumors. [ABSTRACT FROM AUTHOR]

Background and purpose: The volume of excised tumor in contrast‐enhanced areas evaluated via magnetic resonance imaging is known to have a strong influence on the survival of patients with glioblastoma (GBM). In this study, we investigated the effect of tumor resection on the survival of patients with GBM in the 11C‐methionine (MET) accumulation area using MET‐positron emission tomography (MET‐PET). Methods: A total of 26 patients (median age, 69 years; 15 males) who had undergone tumor resection and MET‐PET before and after surgery, after being newly diagnosed with GBM, were included in the study. MET‐PET before and after tumor resection were compared. The association between the decrease in the maximum standardized uptake value (SUV) of the tumor divided by the normal cortical mean SUV (%; ΔT/N), the MET extent of resection (MET‐EOR) from the % reduction in the MET accumulation area (%), and residual MET accumulation area (in cm3; MET‐residual tumor volume [RTV]), as well as the survival time of patients with GBM, were evaluated via univariate analysis. Results: ΔT/N were positively associated with survival (hazard ratio [HR], 0.98 [95% confidence interval (CI), 0.97–0.99], p =.02). MET‐RTV revealed a negative association with survival (HR, 1.02 [95% CI, 1.01–1.04], p =.04). Additionally, MET‐EOR showed a strong trend with survival (HR, 0.99 [95% CI, 0.97–1.01], p =.06). Conclusions: Surgical resection of MET‐accumulated areas in GBM significantly prolongs the survival of patients with GBM. However, a prospective large‐scale multicenter study is needed to confirm our findings. [ABSTRACT FROM AUTHOR]

Abstract Background and purpose The volume of excised tumor in contrast‐enhanced areas evaluated via magnetic resonance imaging is known to have a strong influence on the survival of patients with glioblastoma (GBM). In this study, we investigated the effect of tumor resection on the survival of patients with GBM in the 11C‐methionine (MET) accumulation area using MET‐positron emission tomography (MET‐PET). Methods A total of 26 patients (median age, 69 years; 15 males) who had undergone tumor resection and MET‐PET before and after surgery, after being newly diagnosed with GBM, were included in the study. MET‐PET before and after tumor resection were compared. The association between the decrease in the maximum standardized uptake value (SUV) of the tumor divided by the normal cortical mean SUV (%; ΔT/N), the MET extent of resection (MET‐EOR) from the % reduction in the MET accumulation area (%), and residual MET accumulation area (in cm3; MET‐residual tumor volume [RTV]), as well as the survival time of patients with GBM, were evaluated via univariate analysis. Results ΔT/N were positively associated with survival (hazard ratio [HR], 0.98 [95% confidence interval (CI), 0.97–0.99], p = .02). MET‐RTV revealed a negative association with survival (HR, 1.02 [95% CI, 1.01–1.04], p = .04). Additionally, MET‐EOR showed a strong trend with survival (HR, 0.99 [95% CI, 0.97–1.01], p = .06). Conclusions Surgical resection of MET‐accumulated areas in GBM significantly prolongs the survival of patients with GBM. However, a prospective large‐scale multicenter study is needed to confirm our findings.

Multiple myeloma (MM) is the second most common haematological malignancy and remains incurable despite therapeutic advances. 18F-FDG (FDG) PET/CT is a relevant tool MM for staging and it is the reference imaging technique for treatment evaluation. However, it has limitations, and investigation of other PET tracers is required. Preliminary results with L-methyl-[11C]- methionine (MET), suggest higher sensitivity than 18F-FDG. This study aimed to compare the diagnostic accuracy and prognostic value of 1FDG and MET in MM patients. We prospectively compared FDG and MET PET/CT for assessment of bone disease and extramedullary disease (EMD) in a series of 52 consecutive patients (8 smoldering MM, 18 newly diagnosed MM and 26 relapsed MM patients). Bone marrow (BM) uptake patterns and the detection of focal lesions (FLs) and EMD were compared. Furthermore, FDG PET parameters with known MM prognostic value were explored for both tracers, as well as total lesion MET uptake (TLMU). Median patient age was 61 years (range, 37–83 years), 54% were male, 13% of them were in stage ISS (International Staging System) III, and 31% had high-risk cytogenetics. FDG PET/CT did not detect active disease in 6 patients, while they were shown to be positive by MET PET/CT. Additionally, MET PET/CT identified a higher number of FLs than FDG in more than half of the patients (63%). For prognostication we focussed on the relapsed cohort, due to the low number of progressions in the two other cohorts. Upon using FDG PET/CT in relapsed patients, the presence of more than 3 FLs (HR 4.61, p = 0.056), more than 10 FLs (HR 5.65, p = 0.013), total metabolic tumor volume (TMTV) p50 (HR 4.91, p = 0.049) or TMTV p75 (HR 5.32, p = 0.016) were associated with adverse prognosis. In MET PET/CT analysis, TMTV p50 (HR 4.71, p = 0.056), TMTV p75 (HR 6.27, p = 0.007), TLMU p50 (HR 8.8, p = 0.04) and TLMU p75 (HR 6.3, p = 0.007) adversely affected PFS. This study confirmed the diagnostic and prognostic value of FDG in MM. In addition, it highlights that MET has higher sensitivity than FDG PET/CT for detection of myeloma lesions, including FLs. Moreover, we show, for the first time, the prognostic value of TMTV and TLMU MET PET/CT in the imaging evaluation of MM patients. [ABSTRACT FROM AUTHOR]

Abstract Background The present study tested the possible utility of fractal analysis from l-[methyl-11C]-methionine (MET) uptake in patients with newly diagnosed gliomas for differentiating glioma, especially in relation to isocitrate dehydrogenase 1 (IDH1) mutation status, and as compared with the conventional standardized uptake value (SUV) parameters. Methods Investigations of MET PET/CT were performed retrospectively in 47 patients with newly diagnosed glioma. Tumors were divided into three groups: lower grade glioma (IDH1-mutant diffuse astrocytoma and IDH1-mutant anaplastic astrocytoma), higher grade glioma (IDH1-wildtype diffuse astrocytoma and IDH1-wildtype anaplastic astrocytoma), and glioblastoma. The fractal dimension for tumor, maximum SUV (SUVmax) for tumor (T) and mean SUV for normal contralateral hemisphere (N) were calculated, and the tumor-to-normal (T/N) ratio was determined. Metabolic tumor volume (MTV) and total lesion MET uptake (TLMU) were also measured. Results There were significant differences in SUVmax (p = 0.006) and T/N ratio (p = 0.02) between lower grade glioma and glioblastoma. There were no significant differences among any of the three groups in MTV or TLMU. Significant differences were obtained in the fractal dimension between lower grade glioma and higher grade glioma (p = 0.006) and glioblastoma (p

Abstract Background This study aimed to assess the clinical usefulness of 13N-ammonia and 11C- Methionine (MET) positron emission tomography (PET)/ computed tomography (CT) in the differentiation of residual/recurrent pituitary adenoma (RPA) from the pituitary gland remnant (PGR) after trans-sphenoidal adenomectomy. Methods Between June 2012 and December 2019, a total of 19 patients with a history of trans-sphenoidal adenomectomy before PET/CT scans and histological confirmation of RPA after additional surgery in our hospital were enrolled in this study. Images were interpreted by visual evaluation and semi-quantitative analysis. In semi-quantitative analysis, the maximum standard uptake value (SUVmax) of the target and gray matter was measured and the target uptake/gray matter uptake (T/G) ratio was calculated. Results The T/G ratios of 13N-ammonia were significantly higher in PGR than RPA (1.58 ± 0.69 vs 0.63 ± 1.37, P

Abstract Background The amount of signal decreases when the acquisition duration is shortened. However, it is not clear how this affects the quantitative values. This study aims to clarify the effect of acquisition time shortening in brain tumor PET/CT using 11C-methionine on the quantitative values. Method This study was a retrospective analysis of 30 patients who underwent clinical 11C-methionine PET/CT examination. PET images were acquired in list mode for 10 min. PET images of acquisition duration from 1 to 10 min with 1-min step were reconstructed. We examined the effect on the quantitative values of acquisition duration. We placed a volume of interest to include the entire tumor and regions of interest in the shape of a large crescent in the contralateral hemisphere in 5 contiguous axial slices as normal tissue. Quantitative values examined were maximum, peak, and mean standardized uptake values (SUVmax, SUVpeak, SUVmean), metabolic tumor volume (MTV), and maximum tumor to normal tissue ratio (TNRmax), with each duration compared to that with 10 min. Results SUVmax, MTV, and TNRmax showed the highest values due to the effects of statistical noise when the acquisition time was 1 min. These values were stable when the acquisition duration was > 6 min. SUVpeak and SUVmean showed mostly consistent values regardless of duration. Conclusions SUVmax, MTV, and TNRmax are affected by acquisition time. If the acquisition duration was > 6 min, the fluctuation could be suppressed within 5% in these quantitative values. However, SUVpeak was suggested to be a robust index regardless of the acquisition duration.

A 70-year-old man with a tumor in the nasal and paranasal space, was pathologically diagnosed with an alveolar rhabdomyosarcoma, with right cervical lymph node metastasis. Magnetic resonance imaging revealed a primary tumor in the nasal and paranasal sinuses, with associated intracranial infiltration. 11C-methionine positron emission tomography/computed tomography (PET/CT) revealed increased uptake in the primary tumor and right cervical lymph node metastasis. 18F-fluorodeoxyglucose PET/CT also revealed increased uptake in the primary tumor and right cervical lymph node. However, the physiological brain uptake overlapped with the primary tumor uptake. Our case suggests the usefulness of 11C-methionine PET/CT for accurately assessing the extent of alveolar rhabdomyosarcoma, especially in cases with intracranial infiltration or those approximating the brain. [ABSTRACT FROM AUTHOR]

PurposeThe great spatial and temporal resolution of positron emission tomography might provide the answer for patients with primary hyperparathyroidism (pHPT) and non-localized parathyroid glands. We performed a systematic review of the evidence regarding all investigated tracers.MethodsA study was considered eligible when the following criteria were met: (1) adults ≥17 years old with non-familial pHPT, (2) evaluation of at least one PET isotope, and (3) post-surgical and pathological diagnosis as the gold standard. Performance was expressed in sensitivity and PPV.ResultsTwenty-four papers were included subdivided by radiopharmaceutical: 14 studies investigated L-[11C]Methionine (11C-MET), one [11C]2-hydroxy-N,N,N-trimethylethanamium (11C-CH), six 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG), one 6-[18F] fluoro-L-DOPA (18F-DOPA), and three N-[(18F)Fluoromethyl]-2-hydroxy-N,N-dimethylethanaminium (18F-FCH). The 14 studies investigating MET included a total of 327 patients with 364 lesions. Sensitivity for the detection of a lesion in the correct quadrant had a pooled estimate of 69 % (95 % CI 60-78 %). Heterogeneity was overall high with I2 of 51 % (p = 0.01) for all 14 studies. Pooled PPV ranged from 91 to 100 % with a pooled estimate of 98 % (95 % CI 96-100 %). Of the other investigated tracers, 18-FCH seems the most promising with high diagnostic performance.ConclusionsThe results of our meta-analysis show that 11C-MET PET has an overall good sensitivity and PPV and may be considered a reliable second-line imaging modality to enable minimally invasive parathyroidectomy. Our literature review suggests that 18F-FCH PET may produce even greater accuracy and should be further investigated using both low-dose CT and MRI for anatomical correlation.

Abstract Background The molecular features of isocitrate dehydrogenase (IDH) mutation and chromosome 1p and 19q (1p/19q) codeletion status have pivotal role for differentiating gliomas and have been integrated in the World Health Organization (WHO) classification in 2016. Positron emission tomography (PET) with 3′-deoxy-3′-[18F]fluorothymidine (FLT) has been used to evaluate tumour grade and proliferative activity and compared with l-[methyl-11C]-methionine (MET) in glioma patients. Herein, we evaluated tracer uptakes of MET-PET/CT and FLT-PET/CT for differentiating glioma based on the 2016 WHO classification especially in relation to IDH1 mutation status. Methods In total, 81 patients with newly diagnosed supratentorial glioma were enrolled in this study. They underwent PET/CT studies with MET and FLT before surgery. The molecular features and histopathological diagnosis based on the 2016 WHO classification were determined using surgical specimens. The ratios of the maximum standardized uptake value (SUV) of the tumours to the mean SUV of the contralateral cortex (T/N ratios) were calculated on MET-PET/CT and FLT-PET/CT images. Results The mean T/N ratios of MET-PET/CT and FLT-PET/CT in IDH1-wildtype tumours were significantly higher than those in IDH1-mutant tumours (P < 0.001 and P < 0.001, respectively). Receiver operating characteristic analysis for differentiating IDH1 mutation status showed that the area under the curve of the FLT T/N ratio was significantly larger than that of the MET T/N ratio (P < 0.01). The mean T/N ratio of FLT-PET/CT in IDH1-wildtype tumours was significantly higher than that in IDH1-mutant tumours among grade II and III gliomas (P = 0.005), but this was not the case for MET-PET/CT. Both MET-PET/CT and FLT-PET/CT were able to distinguish between grade II and III gliomas in IDH1-mutant tumours (P = 0.002 and P < 0.001, respectively), but only FLT-PET/CT was able to distinguish between grade III and IV gliomas in IDH1-wildtype tumours (P = 0.029). Conclusion This study showed that FLT-PET/CT can be used to determine the IDH1 mutation status and evaluate glioma grade more accurately than MET-PET/CT. FLT-PET/CT can improve glioma differentiation based on the 2016 WHO classification, but caution must be paid for tumours without contrast enhancement and further studies should be conducted with more cases.

Background: The present study tested the possible utility of fractal analysis from l-[methyl-11C]-methionine (MET) uptake in patients with newly diagnosed gliomas for differentiating glioma, especially in relation to isocitrate dehydrogenase 1 (IDH1) mutation status, and as compared with the conventional standardized uptake value (SUV) parameters. Methods: Investigations of MET PET/CT were performed retrospectively in 47 patients with newly diagnosed glioma. Tumors were divided into three groups: lower grade glioma (IDH1-mutant diffuse astrocytoma and IDH1-mutant anaplastic astrocytoma), higher grade glioma (IDH1-wildtype diffuse astrocytoma and IDH1-wildtype anaplastic astrocytoma), and glioblastoma. The fractal dimension for tumor, maximum SUV (SUVmax) for tumor (T) and mean SUV for normal contralateral hemisphere (N) were calculated, and the tumor-to-normal (T/N) ratio was determined. Metabolic tumor volume (MTV) and total lesion MET uptake (TLMU) were also measured. Results: There were significant differences in SUVmax (p = 0.006) and T/N ratio (p = 0.02) between lower grade glioma and glioblastoma. There were no significant differences among any of the three groups in MTV or TLMU. Significant differences were obtained in the fractal dimension between lower grade glioma and higher grade glioma (p = 0.006) and glioblastoma (p < 0.001). Conclusions: The results of this preliminary study in a small patient population suggest that the fractal dimension using MET PET in patients with newly diagnosed gliomas is useful for differentiating glioma, especially in relation to IDH1 mutation status, which has not been possible with SUV parameters. [ABSTRACT FROM AUTHOR]

Background: This study aimed to assess the clinical usefulness of 13N-ammonia and 11C- Methionine (MET) positron emission tomography (PET)/ computed tomography (CT) in the differentiation of residual/recurrent pituitary adenoma (RPA) from the pituitary gland remnant (PGR) after trans-sphenoidal adenomectomy.Methods: Between June 2012 and December 2019, a total of 19 patients with a history of trans-sphenoidal adenomectomy before PET/CT scans and histological confirmation of RPA after additional surgery in our hospital were enrolled in this study. Images were interpreted by visual evaluation and semi-quantitative analysis. In semi-quantitative analysis, the maximum standard uptake value (SUVmax) of the target and gray matter was measured and the target uptake/gray matter uptake (T/G) ratio was calculated.Results: The T/G ratios of 13N-ammonia were significantly higher in PGR than RPA (1.58 ± 0.69 vs 0.63 ± 1.37, P < 0.001), whereas the T/G ratios of 11C-MET were obviously lower in PGR than RPA (0.78 ± 0.35 vs 2.17 ± 0.54, P < 0.001). Using the canonical discriminant analysis, we calculated the predicted accuracy of RPA (100%), PGR (92.9%), and the overall predicted accuracy (96.43%).Conclusions: The combination of 13N-ammonia and 11C-MET PET/CT is valuable in the differentiation of RPA from PGR after trans-sphenoidal adenomectomy. [ABSTRACT FROM AUTHOR]

Some studies have assessed the expression of dopaminergic dopamine 2 (D2)/3 receptors in prolactinomas and nonfunctioning pituitary adenomas (NFPA) by positron emission tomography/computed tomography (PET/CT) with 11C-raclopride, proving that this modality can be useful to predict the response to treatment with dopamine agonists. However, the use of 11C-labeled radiotracers is limited, as it requires a cyclotron in the PET center. 18F-fallypride is a radiotracer that has proven useful in assessing the expression of D2/3 receptors. As it is labeled with 18F, it can be produced and transported to distant PET centers. There are no studies on the usefulness of 18F-fallypride for the evaluation of patients with prolactinomas and NFPA. The aim of this study was to describe the first case series of patients with prolactinomas and NFPA studied with 18F-fallypride and 11C-methionine PET/CT to reveal D2/3 expression and amino acid (AA) metabolism. 18F-fallypride and 11C-methionine uptake were assessed in a case series of six patients, five with prolactinomas and one with a NFPA, and compared with clinical presentation and follow-up at 6-18 months. All patients presented with macroadenomas, with a wide range of AA metabolism, as revealed by 11C-methionine PET/CT. 18F-fallypride PET/CT identified low to moderate/high D2/3 expression in the tumors. The patient that presented low expression of D2/3 in the tumor and high AA metabolism showed a poor response to DA therapy. 18F-fallypride was able to reveal D2/3 receptor expression in prolactinomas and NFPA, with the advantage of been a more accessible radiotracer in comparison with previous 11C labeled analogs. [ABSTRACT FROM AUTHOR]

Background: The amount of signal decreases when the acquisition duration is shortened. However, it is not clear how this affects the quantitative values. This study aims to clarify the effect of acquisition time shortening in brain tumor PET/CT using 11C-methionine on the quantitative values. Method: This study was a retrospective analysis of 30 patients who underwent clinical 11C-methionine PET/CT examination. PET images were acquired in list mode for 10 min. PET images of acquisition duration from 1 to 10 min with 1-min step were reconstructed. We examined the effect on the quantitative values of acquisition duration. We placed a volume of interest to include the entire tumor and regions of interest in the shape of a large crescent in the contralateral hemisphere in 5 contiguous axial slices as normal tissue. Quantitative values examined were maximum, peak, and mean standardized uptake values (SUVmax, SUVpeak, SUVmean), metabolic tumor volume (MTV), and maximum tumor to normal tissue ratio (TNRmax), with each duration compared to that with 10 min. Results: SUVmax, MTV, and TNRmax showed the highest values due to the effects of statistical noise when the acquisition time was 1 min. These values were stable when the acquisition duration was > 6 min. SUVpeak and SUVmean showed mostly consistent values regardless of duration. Conclusions: SUVmax, MTV, and TNRmax are affected by acquisition time. If the acquisition duration was > 6 min, the fluctuation could be suppressed within 5% in these quantitative values. However, SUVpeak was suggested to be a robust index regardless of the acquisition duration. [ABSTRACT FROM AUTHOR]

Intravascular lymphoma (IVL) is a rare and clinically devastating subtype of extranodal diffuse large B-cell lymphoma with a distinct presentation. Diagnostic difficulty derives from marked variability in clinical presentations and nonspecific laboratory and radiological findings, especially when central nervous system (CNS) symptoms are the only manifestation. Establishing the diagnosis premortem thus remains a major challenge. We describe a 70-year-old male with CNS IVL. He presented with acute onset of neurocognitive impairments. Diffusion-weighted magnetic resonance imaging (MRI) showed multiple high-intensity areas suggesting occlusive cerebrovascular disease due to emboli, but extensive investigations detected no embolic sources. Intracranial neoplasm was included in a differential diagnosis based on elevated serum lactate dehydrogenase and interleukin 2 receptor levels. Gadolinium-enhanced MRI or 18-fluorodeoxyglucose positron emission tomography (PET) failed to demonstrate specific findings leading to a definite diagnosis, while 11C-methionine PET (MET-PET) distinctively demonstrated an area of focally increased MET uptake in the frontal cortex, suggesting the extent of tumor infiltration. Stereotactic biopsy was conducted under MET-PET imaging guidance and immunohistological examinations confirmed the proliferation and aggregation of CD20-positive lymphoma cells within the lumina of small blood vessels. The findings of the present case first suggest that MET-PET may provide important information on the diagnosis of CNS IVL and on the selection of the optimal site for brain biopsy. Further investigation is necessary to clarify whether positive findings on MET-PET are truly specific and pathognomonic for CNS IVL.

Purpose: The aim of our study was to investigate the efficacy of 18F-Fluciclovine brain PET imaging in recurrent gliomas, and to compare the utility of these images to that of contrast enhanced magnetic resonance imaging (MRI) and to [11C-methyl]-L-methionine (11C-Methionine) PET imaging. We also sought to gain insight into the factors affecting the uptake of 18F-FACBC in both tumors and normal brain, and specifically to evaluate how the uptake in these tissues varied over an extended period of time post injection. Methods: Twenty-seven patients with recurrent or progressive primary brain tumor (based on clinical and MRI/CT data) were studied using dynamic 18F-Fluciclovine brain imaging for up to 4 h. Of these, 16 patients also had 11C-Methionine brain scans. Visual findings, semi-quantitative analyses and pharmacokinetic modeling of a subset of the 18F-Fluciclovine images was conducted. The information derived from these analyses were compared to data from 11C-Methionine and to contrast-enhanced MRI. Results: 18F-Fluciclovine was positive for all 27 patients, whereas contrast MRI was indeterminate for three patients. Tumor 18F-Fluciclovine SUVmax ranged from 1.5 to 10.5 (average: 4.5 ± 2.3), while 11C-Methionine's tumor SUVmax ranged from 2.2 to 10.2 (average: 5.0 ± 2.2). Image contrast was higher with 18F-Fluciclovine compared to 11C-Methionine (p < 0.0001). This was due to 18F-Fluciclovine's lower background in normal brain tissue (0.5 ± 0.2 compared to 1.3 ± 0.4 for 11C-Methionine). 18F-Fluciclovine uptake in both normal brain and tumors was well described by a simple one-compartment (three-parameter: Vb,k1,k2) model. Normal brain was found to approach transient equilibrium with a half-time that varied greatly, ranging from 1.5 to 8.3 h (mean 2.7 ± 2.3 h), and achieving a consistent final distribution volume averaging 1.4 ± 0.2 ml/cc. Tumors equilibrated more rapidly (t1/2ranging from 4 to 148 min, average 57 ± 51 min), with an average distribution volume of 3.2 ± 1.1 ml/cc. A qualitative comparison showed that the rate of normal brain uptake of 11C-Methionine was much faster than that of 18F-Fluciclovine. Conclusion: Tumor uptake of 18F-Fluciclovine correlated well with the established brain tumor imaging agent 11C-Methionine but provided significantly higher image contrast. 18F-Fluciclovine may be particularly useful when the contrast MRI is non-diagnostic. Based on the data gathered, we were unable to determine whether Fluciclovine uptake was due solely to recurrent tumor or if inflammation or other processes also contributed. [ABSTRACT FROM AUTHOR]

Background: The molecular features of isocitrate dehydrogenase (IDH) mutation and chromosome 1p and 19q (1p/19q) codeletion status have pivotal role for differentiating gliomas and have been integrated in the World Health Organization (WHO) classification in 2016. Positron emission tomography (PET) with 3′-deoxy-3′-[18F]fluorothymidine (FLT) has been used to evaluate tumour grade and proliferative activity and compared with l-[methyl-11C]-methionine (MET) in glioma patients. Herein, we evaluated tracer uptakes of MET-PET/CT and FLT-PET/CT for differentiating glioma based on the 2016 WHO classification especially in relation to IDH1 mutation status. Methods: In total, 81 patients with newly diagnosed supratentorial glioma were enrolled in this study. They underwent PET/CT studies with MET and FLT before surgery. The molecular features and histopathological diagnosis based on the 2016 WHO classification were determined using surgical specimens. The ratios of the maximum standardized uptake value (SUV) of the tumours to the mean SUV of the contralateral cortex (T/N ratios) were calculated on MET-PET/CT and FLT-PET/CT images. Results: The mean T/N ratios of MET-PET/CT and FLT-PET/CT in IDH1-wildtype tumours were significantly higher than those in IDH1-mutant tumours (P < 0.001 and P < 0.001, respectively). Receiver operating characteristic analysis for differentiating IDH1 mutation status showed that the area under the curve of the FLT T/N ratio was significantly larger than that of the MET T/N ratio (P < 0.01). The mean T/N ratio of FLT-PET/CT in IDH1-wildtype tumours was significantly higher than that in IDH1-mutant tumours among grade II and III gliomas (P = 0.005), but this was not the case for MET-PET/CT. Both MET-PET/CT and FLT-PET/CT were able to distinguish between grade II and III gliomas in IDH1-mutant tumours (P = 0.002 and P < 0.001, respectively), but only FLT-PET/CT was able to distinguish between grade III and IV gliomas in IDH1-wildtype tumours (P = 0.029). Conclusion: This study showed that FLT-PET/CT can be used to determine the IDH1 mutation status and evaluate glioma grade more accurately than MET-PET/CT. FLT-PET/CT can improve glioma differentiation based on the 2016 WHO classification, but caution must be paid for tumours without contrast enhancement and further studies should be conducted with more cases. [ABSTRACT FROM AUTHOR]

Abstract Background On conventional diagnostic imaging, the features of radiation necrosis (RN) are similar to those of local recurrence (LR) of brain metastases (BM). 11C–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 cut-off 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 cut-off 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 cut-off 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 cut-off value.

Objective – study of the diagnostic capabilities of MRI and PET/CT scanners and the available user programs for processing DICOM-images in the implementation of the preoperative planning of stereotactic interventions in patients with deep cerebral gliomas in terms of fusion the scans of a brain.Material and methods. 35 stereotactic surgeries (biopsies and treatment cryoablations) were preplanned and then conducted in patients with brain deep-seated tumors. Patients underwent MRI-scanning in stereotactic conditions and PET/CT scanning with the tumor-specific radiotracer 11C-methionine for stereotactic targeting in preoperative period. Stereotactic planning was conducted on fused MRI/PET images. A co-registration was carried out using a diagnostic workstation Philips and neuronavigation station Medtronic StealthStation S7.Results. A fusion of MRI and PET images using application software is a convenient tool for precise planning of target points and trajectories for insertion stereotactic cannula into a brain. On a fused image the PET-component enables to plan target areas for biopsy and selective ablation of the tumor, due to the ability of a radiotracer to accumulate selectively in the most malignant sites of a tumor. While MRI component, providing a clear anatomical visualization, allows the planning safe trajectories of stereotactic access out of eloquent areas, pathways of brain and intracerebral vessels, which reduces the risk of intraoperative complications. In addition, MRI provides imaging of fiducial markers for stereotactic calculations.Conclusion. High efficiency of preoperative planning on fused MRI/PET scans was demonstrated. The proposed planning method allows to increase the effectiveness of biopsies and to prevent the prolonged growth of brain glial tumors, even when their selective stereotactic ablation, as well as to ensure a low level of postoperative complications.

Objective(s): 18F-fluciclovine (trans-1-amino-3-[18F] fluorocyclobutanecarboxylic acid, [FACBC]) is an artificial amino acid radiotracer used for positron emission tomography (PET) studies, which is metabolically stable in vivo and has a long half-life. It has already been shown that FACBC-PET is useful for glioma imaging. However, there have been no reports evaluating the efficiency of FACBC-PET in the diagnosis of brain tumors in comparison with other PET tracers in clinical studies. The purpose of this study was to investigate the efficacy of FACBC-PET imaging in glioma diagnosis, compared to l-methyl-11C-methionine (MET)-PET.Methods: Six consecutive patients (four male, two female), who were clinically suspected of having high- or low-grade glioma, received both FACBC-PET and MET-PET within a two-week interval. T1-weighted, contrast-enhanced, T1-weighted, and fluid-attenuated inversion recovery magnetic resonance imaging was performed to assist with subsequent tissue resection. Visual findings and semi-quantitative analyses of FACBC and MET uptake, using standardized uptake values (SUVs) and lesion-to-contralateral normal brain tissue (LN) ratios, were evaluated to compare PET images.Results: SUVs for FACBC were lower than those for MET in the non-lesion cerebral cortex, brain stem, and cerebellar hemisphere. There was a weak positive correlation between FACBC and MET uptake in glioma tissue, although L/N ratios for FACBC were higher than those for MET in all the cases.Conclusion: FACBC-PET showed higher contrast than MET-PET by both visual and semi-quantitative analyses and may therefore provide better assessment for the detection of glioma. This study was registered as clinical trial (No. JapicCTI-132289).

Prognosis of IDH ( IDHwt ) wild-type gliomas is worse compared to IDH -mutant tumors regardless of histological criteria for glioblastoma. However, there is still uncertainty regarding favorable course of disease and predictors of long-term survival in IDHwt gliomas., Objective: To study the metabolic characteristics of IDH1wt diffuse astrocytomas using 11 C-methionine PET/CT and prognostic significance of PET-associated parameters for disease-free survival., Material and Methods: We analyzed 79 adults with IDH1wt diffuse gliomas. Quantitative analysis consisted of 11 C-methionine accumulation index and metabolic tumor volume. Kaplan-Meier and Cox analyses were used to determine prognostic significance of histological findings and PET parameters., Results: Glioblastoma and astrocytoma grade 2 or 3 were diagnosed in 41% and 59% of patients, respectively. Accumulation index significantly differed between astrocytomas grade 2 and 3 ( p =0.03). Significant predictors of disease-free survival were age, histological type of astrocytoma and tumor grade, contrast enhancement, PET-associated biomarkers (accumulation index and metabolic tumor volume) and compliance of metabolic pattern with glioblastoma syndrome ( p <0.05). Disease-free survival >24 months was established for age <41 years, maximum accumulation index <1.64, tumor accumulation index <1.39 and metabolic tumor volume <13.44 cm 3 . In multivariate Cox analysis, independent predictors of disease-free survival were age and PET syndrome of glioblastoma., Conclusion: Diffuse IDH1wt gliomas are a heterogeneous group differing in metabolic characteristics and prognosis. PET/CT with 11 C-methionine may be effective for stratifying patients into groups with unfavorable and favorable prognosis, as well as assessment of advisability of in-depth searching for IDH1 / IDH2 mutation.

Objective: To study 11C-methionine (MET) metabolism in gliomas using CNS tumor biobank imaging data., Material and Methods: MRI and 11C-MET PET/CT were performed in 225 patients (49±14 years, M/F=84/101) according to standard protocols with analysis of 11C-MET accumulation index and volumetric parameters (V&#95;FLAIR, V&#95;PET and V&#95;PET/FLAIR). These results were compared with molecular genetic testing and 2-year overall survival., Results: We examined 225 patients with gliomas (97 glioblastomas, 70 astrocytomas, 58 oligodendrogliomas). Accumulation index and volume of 11C-MET in glioblastomas were significantly higher in the general group (AI=2.90, Se 69%, Sp 76%, AUC 0.76; V&#95;PET=24.3 cm 3 , Se 67%, Sp 60%, AUC 0.65; V&#95;PET/FLAIR 0.46, Se 60%, Sp 69%, AUC 0.67) and within the group of astrocytomas (AI=2.93, Se 68%, Sp 89%, AUC 0.84; V&#95;PET=8.06 cm 3 , Se 91%, Sp 35%, AUC 0.66; V&#95;PET/FLAIR 0.27, Se 77%, Sp 60%, AUC 0.71). The median 2-year overall survival in patients with glioblastomas was 13 months that was significantly lower compared to IDH «+» gliomas ( p <0.0001). There was a relationship between high accumulation index of 11C-MET and shorter overall survival in patients with glioblastomas. Significantly higher AI >3.59 (Se 89%, Sp 67%, AUC 0.79) was additionally obtained in subgroup of patients with glioblastomas >50 years ( n =34) for EGFR «+» tumors., Conclusion: We found variable 11C-MET metabolism in WHO 2021 gliomas and confirmed significant difference in metabolic activity and volume of 11C-MET accumulation in glioblastomas compared to IDH «+» gliomas. Moreover, we revealed the relationship between high accumulation index and shorter survival. Analysis of 11C-MET metabolism in patients over 50 years old revealed higher accumulation index in the EGFR «+» group. Further comparison of these imaging methods and assessment of other significant mutations are necessary to identify the anatomical and metabolic patterns of IDH «+» gliomas.

The aim of the review is to highlight articles published in 2017 in the Annals of Nuclear Medicine, an official peer-reviewed journal of the Japanese Society of Nuclear Medicine. Among all published manuscripts during the past year, we conducted a subjective selection of the most relevant topics. Fourteen fascinating articles are included in this review, ranging in topic from preclinical to clinical arenas. [ABSTRACT FROM AUTHOR]

The paper presents a case of a 52-year-old female patient with pleomorphic malignant fibrous histiocytoma/ undifferentiated pleomorphic sarcoma of the left atrium. One year after surgical resection of the primary tumor, microsurgical removal of the right parietal lobe metastatic tumor was performed. PET/CT with 11C-methionine and 18F-FDG performed 2 months after surgical resection of brain metastasis revealed local recurrence of sarcoma in the left atrium and left lateral ventricle metastases. This clinical case demonstrates high diagnostic accuracy of PET/CT with 18F-FDG and 11C-methionine in detecting local recurrence of cardiac undifferentiated sarcoma, however, PET/CT with 11C-methionine appears to be superior to PET/CT with18F-FDG in detecting brain metastasis.

A method of 11C-methionine synthesis using ‘bubbling’ method is presented. 11C-methionine was synthesized via 11C methylation from L-cysteine thiolactone (2 mg) in a 300 μL solution of 2:1:1 (v/v) 1 M NaOH, ethanol, and water at ambient temperature (85°C, 5 min). The radiochemical purity of radiotracer was higher than 99% and enantiomeric purity (L-11C-methionine) was 91.6 ± 0.4%. The final product met the requirements of European Pharmacopoeia monograph. The proposed 11C-methionine synthesis is a reliable tool for routine manufacturing in clinical applications and animal studies.

Objective: to study the possibilities of enhancing the efficiency of differential diagnosis of solitary lung masses by optimizing the quantitative analysis of positron emission tomography (PET) data when two radiopharmaceuticals (RP) (18F-fluorodeoxyglucose (18F-FDG) and 11C-methionine) are used alone and in combination.Material and methods. A comprehensive examination involving 18F-FDG and 11C-methionine PET was made in 116 patients with solitary lung masses of various genesis. A final diagnosis in the examinees was established from the results of postoperative material morphological analysis and/or laboratory tests and those of X-ray follow-up.Results. No 18F-FDG and 11C-methionine hyperfixation was found in patients with benign tumors and in the majority of patients with focal pneumofibrosis. At 18F-FDG and 11C-methionine PET, RP accumulation was recorded in all patients with lung cancer (LC) and in patients with inflammatory diseases. Three patients with 18F-FDG PET-negative typical carcinoid tumors were noted to have increased 11C-methionine uptake. At 11C-methionine PET, RP accumulation was recorded in the projection of formation in all the patients with LC and in 38 of the 42 patients with inflammatory diseases. Regardless of the used RP, the Standardized Uptake Value (SUV) was significantly lower in the patients with inflammatory diseases than in those with LC (p ≤ 0.05).Conclusions. When RP is used alone, the diagnostic efficiency of 11C-methionine PET in the differential diagnosis of lung tumors and inflammations is higher than that of 18F-FDG PET. At the same time, the highest informative value of PET is seen when 18FFDG and 11C-methionine are used in combination.

Objective: We evaluated the uptake of 2-deoxy-2-18F-fluoro-D-glucose (FDG) and L-[methyl-11C]-methionine (MET) in patients with newly diagnosed intracranial meningiomas and correlated the results with tumor proliferation.Methods: Data from 22 patients with newly diagnosed intracranial meningioma (12 grade I and 10 grade II) who underwent both FDG and MET brain PET/CT studies were retrospectively analyzed. The PET images were evaluated by a qualitative method and semiquantitative analysis using standardized uptake value (SUV) (SUVmax and SUVpeak) and tumor-to-reference tissue ratio (Tmax/N ratio and Tpeak/N ratio). Proliferative activity as indicated by the Ki-67 index was estimated in tissue specimens.Results: MET PET/CT showed a higher detection rate of meningioma than did FDG PET/CT (100 vs. 46%, respectively). The Tmax/N ratio and Tpeak/N ratio on MET PET/CT were significantly higher than those on FDG PET/CT (p < 0.001 and p < 0.001, respectively). There was a significant difference between grades I and II with respect to FDG SUVmax (p = 0.003), FDG SUVpeak (p = 0.003), FDG Tmax/N ratio (p = 0.02), FDG Tpeak/N ratio (p = 0.006), MET SUVmax (p = 0.002), MET SUVpeak (p = 0.002), MET Tmax/N ratio (p = 0.002), and MET Tpeak/N ratio (p = 0.002). There was a significant correlation between Ki-67 index and FDG PET/CT for SUVmax (p = 0.02), SUVpeak (p = 0.005), and Tpeak/N ratio (p = 0.05) and between Ki-67 index and MET PET/CT for SUVmax (p = 0.004), SUVpeak (p = 0.007), Tmax/N ratio (p = 0.002), and Tpeak/N ratio (p = 0.004).Conclusion: MET PET/CT showed a high sensitivity compared with FDG PET/CT for detection of newly diagnosed WHO grades I and II intracranial meningiomas. Both FDG and MET uptake were found to be useful for evaluating tumor proliferation in meningiomas. [ABSTRACT FROM AUTHOR]