Uptake Of 11C-methionine Research Articles

11C-Methionine uptake in meningiomas after stereotactic radiotherapy

Objective11C-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.MethodsThis 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.ResultsMedian (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].ConclusionsOur 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.

Maximum standardized uptake value in 11C-methionine positron emission tomography may predict the prognosis of patients with oral squamous cell carcinoma.

The present study aimed to elucidate the correlation between the uptake of 11C-methionine (MET) by a primary tumor and the survival of patients with oral squamous cell carcinoma (OSCC). This study enrolled 31 patients who underwent radical surgery for OSCC. The patients underwent pretreatment MET-positron emission tomography (PET) scanning. We analyzed correlations between the maximum standardized uptake value (SUVmax) of MET-PET in a primary tumor and the clinicopathological features. Further, we compared overall survival (OS), disease-specific survival (DSS), and loco-regional recurrence (LRR) rates between the two groups according to SUVmax of MET-PET. SUVmax of MET-PET in a primary tumor was higher in patients with advanced T-classification and advanced clinical stage, with significant differences (P = 0.001 and P = 0.016, respectively). The patients with SUVmax of MET-PET ≥ 4.4 showed significantly lower DSS rates and higher LRR rates than those with SUVmax of < 4.4 (P = 0.015 and P = 0.016, respectively). SUVmax of MET-PET and OS rates showed no significant correlation (P = 0.073). The present study revealed that SUVmax of MET-PET may predict clinical outcomes and prognosis in patients with OSCC who underwent radical surgery.

Loss of methylthioadenosine phosphorylase immunoreactivity correlates with poor prognosis and elevated uptake of 11C-methionine in IDH-mutant astrocytoma.

The proximate localization of MTAP, which encodes methylthioadenosine phosphorylase, and CDKN2A/B on Chromosome 9q21 has allowed the loss of MTAP expression as a surrogate for homozygous deletion of CDKN2A/B. This study aimed to determine whether MTAP status correlates with clinical outcomes and 11C-methionine uptake in astrocytomas with IDH mutations. We conducted immunohistochemistry for MTAP in 30 patients with astrocytoma, IDH-mutant who underwent 11C-methionine positron emission tomography scans prior to surgical resection. The tumor-to-normal (T/N) ratio of 11C-methionine uptake was calculated using the mean standardized uptake value (SUV) for tumor and normal brain tissues. Cox regression analysis was used for multivariate survival analysis. Among IDH-mutant astrocytomas, 26.7% (8/30) exhibited the loss of cytoplasmic MTAP expression, whereas 73.3% (22/30) tumors retained MTAP expression. The median progression-free survival (PFS) was significantly shorter in patients with MTAP loss than those with MTAP retention (1.88years vs. 6.80years, p = 0.003). The median overall survival (OS) was also shorter in patients with MTAP loss than in MTAP-retaining counterparts (5.23years vs. 10.69years, p = 0.019). Multivariate analysis identified MTAP status (hazard ratio (HR), 0.081) and extent of resection (HR, 0.104) as independent prognostic factors for PFS. Astrocytomas lacking cytoplasmic MTAP expression showed a significantly higher median T/N ratio for 11C-methionine uptake than tumors retaining MTAP (2.12 vs. 1.65, p = 0.012). Our study revealed that the loss of MTAP expression correlates with poor prognosis and an elevated T/N ratio of 11C-methionine uptake in astrocytoma, IDH-mutant.

10268-NI-13 T2-FLAIR MISMATCH SIGN CORRELATES WITH11C-METHIONINE UPTAKE IN LOWER-GRADE DIFFUSE GLIOMAS

Abstract PURPOSE The T2-FLAIR mismatch sign is recognized as an imaging finding highly suggestive of IDH-mutant astrocytomas. This study was designed to determine whether the T2-FLAIR mismatch sign correlates with uptake of 11C-methionine in lower-grade gliomas. METHODS We included 78 histopathologically verified lower-grade gliomas (grade 2: 31 cases, grade 3: 47 cases) in this study. 78 patients underwent 11C-methionine positron emission tomography (MET-PET) scans and magnetic resonance (MR) imaging scans prior to histological diagnosis. The tumor-to-normal ratio (T/N) of 11C-methionine uptake was calculated by dividing the maximum standardized uptake value (SUV) for the tumor by the mean SUV of the normal brain. MR imaging scans were evaluated for the presence of the T2-FLAIR mismatch sign by three independent reviewers. We compared molecular status, the T2-FLAIR mismatch sign and 11C-methionine uptake among patients with different lower-grade glioma molecular types. RESULTS The 78 lower-grade gliomas were assigned to one of three molecular groups: Group A (IDH-mutant and 1p/19q non-codeleted, n=22), Group O (IDH-mutant and 1p/19q codeleted, n=20), and Group W (IDH wildtype, n=36). T2-FLAIR mismatch was found in 16 cases (20.5%) that were comprised of 8 (36.4%), 0 (0%), 8 (22.2%) cases in the molecular group A, O and W, respectively. The median T/N ratio of MET-PET in tumors with T2-FLAIR mismatch was 1.50, which was significantly lower than that of tumors without T2-FLAIR mismatch (1.83, p&amp;lt;0.001, Mann-Whitney U test). In the Groups A and W (excluding Group O), the median T/N ratio on MET-PET in groups A and W (but not group O) with T2-FLAIR mismatch was 1.50, which was significantly lower than that of tumors without T2-FLAIR mismatch (1.81, p=0.002, Mann-Whitney U test). CONCLUSION The T2-FLAIR mismatch sign correlated with lower 11C-methionine uptake in lower grade gliomas.

NIMG-65. METHYLTHIOADENOSINE PHOSPHORYLASE STATUS CORRELATES WITH CLINICAL OUTCOME AND11C-METHIONINE UPTAKE IN ASTROCYTOMA, IDH-MUTANT

Abstract PURPOSE Methylthioadenosine phosphorylase (MTAP) immuno histochemistry staining has been proposed as a surrogate of Cyclin-dependent kinase inhibitor 2A homozygous deletion (CDKN2A HD) in various types of tumors. This study was designed to determine whether MTAP status correlates with clinical outcome and uptake of 11C-methionine in astrocytoma, IDH-mutant. METHODS We conducted a MTAP immunohistochemistry staining of 30 astrocytoma, IDH-mutant patients who underwent 11C-methionine positron emission tomography scans prior to surgical resection from 2000 to 2020. The tumor-to-normal (T/N) ratio of 11C-methionine uptake was calculated by dividing the mean standardized uptake value (SUV) for the tumor by the mean SUV of the normal brain. RESULTS Eight (26.7%) of the thirty astrocytoma, IDH-mutant patients exhibited loss of cytoplasmic MTAP expression, which is accompanied with a poor prognosis. The median progression free survival (PFS) in astrocytoma, IDH-mutant patients with loss of MTAP was 1.88 years and significantly shorter than that of those with MTAP retention (6.80 years, p = 0.003). The median Overall survival in astrocytoma, IDH-mutant patients with loss of MTAP was 5.23 years, again significantly shorter than that of those with MTAP retention (10.69 years, p = 0.0191). Multivariate analysis revealed that MTAP status was an independent prognostic marker for PFS in astrocytoma, IDH-mutant patients. The median T/N ratio in tumors with loss of cytoplasmic MTAP expression was 2.12 (IQR 1.92-2.50), i.e., significantly higher than that of tumors with MTAP retention (1.65, IQR 1.23-1.94, p = 0.0116, U test). Thirteen (59.1%) of twenty-two patients with MTAP retention recurred and nine patients underwent a second surgery after radiation treatment with or without chemotherapy. Three (33.3%) of the nine recurrent patients showed loss of MTAP immunoreactivity, suggesting a role for this loss in tumor progression. CONCLUSION Our study showed MTAP status to correlate with clinical outcome and T/N ratio of 11C-methionine in astrocytoma, IDH-mutant patients.

T2-FLAIR mismatch sign correlates with 11C-methionine uptake in lower-grade diffuse gliomas.

The T2-FLAIR mismatch sign is recognized as an imaging finding highly suggestive of IDH-mutant astrocytomas. This study was designed to determine whether the T2-FLAIR mismatch sign correlates with uptake of 11C-methionine in lower-grade gliomas. We included 78 histopathologically verified lower-grade gliomas (grade 2: 31 cases, grade 3: 47 cases) in this study. 78 patients underwent 11C-methionine positron emission tomography (MET-PET) scans and magnetic resonance (MR) imaging scans prior to histological diagnosis. The tumor-to-normal ratio (T/N) of 11C-methionine uptake was calculated by dividing the maximum standardized uptake value (SUV) for the tumor by the mean SUV of the normal brain. MR imaging scans were evaluated for the presence of the T2-FLAIR mismatch sign by three independent reviewers. We compared molecular status, the T2-FLAIR mismatch sign and 11C-methionine uptake among patients with different lower-grade glioma molecular types. The 78 lower-grade gliomas were assigned to one of three molecular groups: Group A (IDH-mutant and 1p/19q non-codeleted, n = 22), Group O (IDH-mutant and 1p/19q codeleted, n = 20), and Group W (IDH wildtype, n = 36). T2-FLAIR mismatch was found in 16 cases (20.5%) that were comprised of 8 (36.4%), 0 (0%), 8 (22.2%) cases in the molecular group A, O and W, respectively. The median T/N ratio of MET-PET in tumors with T2-FLAIR mismatch was 1.50, which was significantly lower than that of tumors without T2-FLAIR mismatch (1.83, p < 0.001, Mann-Whitney U test). In the Groups A and W (excluding Group O), the median T/N ratio on MET-PET in groups A and W (but not group O) with T2-FLAIR mismatch was 1.50, which was significantly lower than that of tumors without T2-FLAIR mismatch (1.81, p = 0.002, Mann-Whitney U test). The T2-FLAIR mismatch sign correlated with lower 11C-methionine uptake in lower grade gliomas.

NI-1 METHYLTHIOADENOSINE PHOSPHOLYLASE STATUS CORRELATES WITH PROGNOSIS AND METHIONINE UPTAKE IN IDH MUTANT ASTROCYTOMA

Abstract Purpose Methylthioadenosine phosphorylase (MTAP) immunohistochemistry staining has been proposed as a surrogate of Cyclin-dependent kinase inhibitor 2A homozygous deletion (CDKN2A HD) in various type of tumors. This study was designed to determine whether MTAP status correlates with clinical outcome and uptake of 11C-methionine in astrocytoma with IDH mutations. Methods We conducted a MTAP immunohistochemistry staining of 30 IDH-mutant astrocytoma patients who underwent 11C-methionine positron emission tomography scans prior to surgical resection from 2000 to 2020. The tumor-to-normal ratio (T/N) of 11C-methionine uptake was calculated by dividing the mean standardized uptake value (SUV) for the tumor by the mean SUV of the normal brain. Results Eight of the thirty astrocytomas harboring IDH mutations exhibited loss of cytoplasmic MTAP expression, which is accompanied with a poor prognosis. The median progression free survival (PFS) in IDH-mutant astrocytoma patients with loss of MTAP was 1.88 years, significantly shorter than that of those with MTAP retention (6.80 years, p=0.003). The median Overall survival (OS) in IDH-mutant astrocytoma patients with loss of MTAP was 5.23 years, again significantly shorter than that of those with MTAP retention (p=0.0191). Multivariate analysis revealed MTAP status to be an independent prognostic marker for PFS in IDH-mutant astrocytoma patients. The median T/N ratio in tumors with loss of cytoplasmic MTAP expression was 2.12 (IQR 1.92-2.50), i.e., significantly higher than that of tumors with MTAP retention (1.65, IQR 1.23-1.94, p=0.0116, U test). Conclusion Our study showed MTAP status to correlate with clinical outcome and T/N ratio of astrocytoma patients with IDH mutations.

Localization of TSH-secreting pituitary adenoma using 11C-methionine image subtraction

BackgroundPituitary adenomas (PA) affect ~ 1:1200 of the population and can cause a wide range of symptoms due to hormone over-secretion, loss of normal pituitary gland function and/or compression of visual pathways, resulting in significantly impaired quality of life. Surgery is potentially curative if the location of the adenoma can be determined. However, standard structural (anatomical) imaging, in the form of MRI, is unable to locate all tumors, especially microadenomas (< 1 cm diameter). In such cases, functional imaging [11C-methionine PET/CT (Met-PET)] can facilitate tumor detection, although may be inconclusive when the adenoma is less metabolically active. We, therefore, explored whether subtraction imaging, comparing findings between two Met-PET scans with medical therapy-induced suppression of tumor activity in the intervening period, could increase confidence in adenoma localization. In addition, we assessed whether normalization to a reference region improved consistency of pituitary gland signal in healthy volunteers who underwent two Met-PET scans without medical suppression.ResultsWe found that the mean percentage differences in maximum pituitary uptake between two Met-PET scans in healthy volunteers were 2.4% for (SUVr) [cerebellum], 8.8% for SUVr [pons], 5.2% for SUVr [gray matter] and 23.1% for the SUVbw [no region]. Laterality, as measured by contrast–noise ratio (CNR), indicated the correct location of the adenoma in all three image types with mean CNR values of 6.2, 8.1 and 11.1 for SUVbw, SUVbwSub and SUVrSub [cerebellum], respectively. Subtraction imaging improved CNR in 60% and 100% of patients when using images generated from SUVbw [no region] and SUVr [cerebellum] scans compared to standard clinical SUVbw imaging.ConclusionsMet-PET scans should be normalized to the cerebellum to minimize the effects of physiological variation in pituitary gland uptake of 11C-methionine, especially when comparing serial imaging. Subtraction imaging following endocrine suppression of tumor function improved lateralization of PA when compared with single time point clinical Met-PET but, importantly, only if the images were normalized to the cerebellum prior to subtraction.

Usefulness of positron emission tomography for differentiating gliomas according to the 2016 World Health Organization classification of tumors of the central nervous system.

Positron emission tomography (PET) is important in the noninvasive diagnostic imaging of gliomas. There are many PET studies on glioma diagnosis based on the 2007 WHO classification; however, there are no studies on glioma diagnosis using the new classification (the 2016 WHO classification). Here, the authors investigated the relationship between uptake of 11C-methionine (MET), 11C-choline (CHO), and 18F-fluorodeoxyglucose (FDG) on PET imaging and isocitrate dehydrogenase (IDH) status (wild-type [IDH-wt] or mutant [IDH-mut]) in astrocytic and oligodendroglial tumors according to the 2016 WHO classification. In total, 105 patients with newly diagnosed cerebral gliomas (6 diffuse astrocytomas [DAs] with IDH-wt, 6 DAs with IDH-mut, 7 anaplastic astrocytomas [AAs] with IDH-wt, 24 AAs with IDH-mut, 26 glioblastomas [GBMs] with IDH-wt, 5 GBMs with IDH-mut, 19 oligodendrogliomas [ODs], and 12 anaplastic oligodendrogliomas [AOs]) were included. All OD and AO patients had both IDH-mut and 1p/19q codeletion. The maximum standardized uptake value (SUV) of the tumor/mean SUV of normal cortex (T/N) ratios for MET, CHO, and FDG were calculated, and the mean T/N ratios of DA, AA, and GBM with IDH-wt and IDH-mut were compared. The diagnostic accuracy for distinguishing gliomas with IDH-wt from those with IDH-mut was assessed using receiver operating characteristic (ROC) curve analysis of the mean T/N ratios for the 3 PET tracers. There were significant differences in the mean T/N ratios for all 3 PET tracers between the IDH-wt and IDH-mut groups of all histological classifications (p < 0.001). Among the 27 gliomas with mean T/N ratios higher than the cutoff values for all 3 PET tracers, 23 (85.2%) were classified into the IDH-wt group using ROC analysis. In DA, there were no significant differences in the T/N ratios for MET, CHO, and FDG between the IDH-wt and IDH-mut groups. In AA, the mean T/N ratios of all 3 PET tracers in the IDH-wt group were significantly higher than those in the IDH-mut group (p < 0.01). In GBM, the mean T/N ratio in the IDH-wt group was significantly higher than that in the IDH-mut group for both MET (p = 0.034) and CHO (p = 0.01). However, there was no significant difference in the ratio for FDG. PET imaging using MET, CHO, and FDG was suggested to be informative for preoperatively differentiating gliomas according to the 2016 WHO classification, particularly for differentiating IDH-wt and IDH-mut tumors.

18F-Fluciclovine (18F-FACBC) PET imaging of recurrent brain tumors

PurposeThe 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.MethodsTwenty-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.Results18F-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.ConclusionTumor 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.

Evaluation of 11C-Methionine PET and Anatomic MRI Associations in Diffuse Intrinsic Pontine Glioma.

The role of metabolic imaging in the diagnosis, treatment, and response assessment of diffuse intrinsic pontine glioma (DIPG) is poorly defined. We investigated the uptake of 11C-methionine in pediatric patients with newly diagnosed DIPG and evaluated the associations of 11C-methionine PET metrics with conventional MRI indices and survival outcomes. Methods: Twenty-two patients with newly diagnosed DIPG were prospectively enrolled on an institutional review board-approved investigational study of 11C-methionine PET. All patients underwent baseline 11C-methionine PET/CT, and initial treatment-response scans after chemotherapy or radiation therapy were obtained for 17 patients. Typical and atypical DIPGs were assessed clinically and radiographically and defined by multidisciplinary consensus. Three-dimensional regions of interest, reviewed by consensus between a nuclear medicine physician and a radiation oncologist, were delineated after coregistration of PET and MR images. Associations of 11C-methionine uptake intensity and uniformity with survival, along with associations between 11C-methionine uptake and conventional MRI tumor indices over time, were evaluated. 11C-methionine PET voxel values within regions of interest were assessed as threshold values across proportions of the study population, and 11C-methionine uptake at baseline was assessed relative to MRI-defined tumor progression. Results:11C-methionine uptake above that of uninvolved brain tissue was observed in 18 of 22 baseline scans (82%) and 15 of 17 initial response scans (88%). 11C-methionine avidity within MRI-defined tumor was limited in extent, with 11 of 18 positive baseline 11C-methionine PET scans (61%) showing less than 25% 11C-methionine-avid tumor. The increase in total tumor volume with 11C-methionine PET was relatively limited (17.2%; interquartile range, 6.53%-38.90%), as was the extent of 11C-methionine uptake beyond the MRI-defined tumor (2.2%; interquartile range, 0.55%-10.88%). Although baseline 11C-methionine PET intensity and uniformity metrics did not correlate with survival outcomes, initial 11C-methionine avidity overlapped with recurrent tumor in 100% of cases. A clinical diagnosis of atypical DIPG was associated with borderline significantly prolonged progression-free survival (P = 0.07), yet 11C-methionine PET indices at diagnosis did not differ significantly between atypical and typical DIPGs. Conclusion: Most newly diagnosed DIPGs are successfully visualized by 11C-methionine PET. Baseline 11C-methionine uptake delineates regions at increased risk for recurrence, yet intensity and uniformity metrics did not correlate with treatment outcomes in children with DIPG in this study.

Stereotactic image-based histological analysis reveals a correlation between 11C-methionine uptake and MGMT promoter methylation in non-enhancing gliomas.

Gliomas are genetically and histopathologically heterogeneous. Intratumoral heterogeneity in the MGMT promoter methylation status is an important clinical biomarker of glioblastoma. A higher uptake of 11C-methionine in positron-emission tomography (PET) reportedly reflects increased MGMT promoter methylation; however, non-stereotactic comparison of MGMT methylation and 11C-methionine PET images may not be accurate. The present study examined the correlation between 11C-methionine uptake and MGMT promoter methylation in non-enhancing gliomas using stereotactic image-based histological analysis. Data were collected from 9 patients with newly diagnosed non-enhancing glioma who underwent magnetic resonance imaging and 11C-methionine PET during pre-surgical examination. Clinical data were also collected from 3 patients during repeat surgery. The correlation between 11C-methionine uptake and MGMT methylation or cell density was analyzed using histological specimens obtained by multiple stereotactic sampling and an exact local comparison of 11C-methionine PET images and histological specimens was made. A total of 31 stereotactic sample sites were identified. In newly diagnosed cases, the tumor to normal uptake (T/N) ratio revealed a significant positive correlation with MGMT methylation (R=0.54, P=0.009) and a marginal correlation with cell density (R=0.42, P=0.05). In recurrent cases, the T/N ratio demonstrated no correlation with MGMT methylation (R=0.01, P=0.97) or cell density (R=0.15, P=0.70). An increased uptake of 11C-methionine in PET may reflect increased MGMT promoter methylation according to stereotactic image-based histological analysis. 11C-methionine PET could therefore be a useful tool for detecting regional MGMT promoter methylation in non-enhancing primary glioma.

DIAGNOSTIC UTILITY OF PET/CT WITH 11C-METHIONINE IN PATIENTS WITH LYMPHOMAS

Aim: to study the role of combined positron emission and computed tomography (PET/CT) with 11C-methionine in the diagnosis of patients with different types of lymphoma. Material and methods. Uptake of 11C-methionine and 18F-FDG was studied with PeT/CT in 24 patients with histologically verified lymphoma. All patients underwent studies with both radiopharmaceuticals. A total of 48 studies were performed. Results. All 24 patients had abnormal sites of pathological uptake of 11C-methionine and 18F-FDG. Regions of abnormal sites of metabolic activity were coinciding in examinations with both radiopharmaceuticals. The average uptake rate of 18F-FDG and 11C-methionine were 9,45 ± 1,3 and 6,7 ± 0,4, (p = 0,05) respectively. In patients with Hodgkin's lymphoma (HL) and aggressive non-Hodgkin's lymphoma (NHL) in comparison with indolent NHL patients the metabolic activity of the pathological focuses in examinations with both radiopharmaceuticals had a significant difference in the accumulation rate, depending on the degree of malignancy-p = 0,01 and p = 0,001, respectively. The sensitivity and specificity of PET/CT with 11C-methionine was 94,4% and 83,3%, respectively. The threshold value of SUVmax &gt; 5,6 (p &lt;0,0001), allows to differentiate lymphomas according to the degree of malignancy. Conclusion. Most sites of tumor involvement in patients with HL and NHL well visualized using 11C-metnionine PET/ CT. All tumor sites had a different level of metabolic activity, higher in patients with aggressive NHL and HL. However it's utility in the abdomen is limited by uptake in normal structures.

ATRX status correlates with 11C-methionine uptake in WHO grade II and III gliomas with IDH1 mutations.

Recent studies on gliomas have shown frequent alterations in the alpha-thalassemia/mental retardation syndrome X-linked gene (ATRX). This study was designed to determine whether ATRX status correlates with uptake of 11C-methionine in WHO grades II and III gliomas. Sixty-two patients underwent 11C-methionine positron emission tomography scans prior to histological diagnosis. The tumor-to-normal ratio (T/N) of 11C-methionine uptake was calculated by dividing the maximum standardized uptake value (SUV) for the tumor by the mean SUV of the normal brain. After surgery, tumor samples were subjected to immunohistochemistry for ATRX and IDH1-R132H followed by IDH1/2 sequencing. Twenty-seven of the sixty-two patients were found to have the IDH mutation. Nine of the twenty-seven gliomas harboring IDH mutations exhibited loss of nuclear ATRX expression, which is accompanied with an astrocytic tumor lineage and a poor prognosis. The mean T/N ratio in tumors with loss of nuclear ATRX expression was 2.20 ± 0.53, i.e., significantly lower than that of tumors with ATRX retention (3.28 ± 1.32, p = 0.0171, U test). Our study showed ATRX status to correlate with the T/N ratio and the outcomes of WHO grade II and III glioma patients with the IDH1 mutation. Our data provide new information on the biology and imaging characteristics of gliomas.

11C-Methionine PET of Myocardial Inflammation in a Rat Model of Experimental Autoimmune Myocarditis.

Autoimmune myocarditis was induced by immunizing Lewis rats twice with porcine cardiac myosin and Freund complete adjuvant. Control animals were treated with adjuvant alone. Dual-tracer autoradiography was performed to assess 14C-methionine uptake and to compare the distributions of 14C-methionine versus 18F-FDG. Hematoxylin and eosin staining and anti-CD68 macrophage staining were performed for histologic analysis. Additionally, cardiac 11C-methionine PET was performed to evaluate the feasibility of in vivo imaging. 18F-FDG PET was also conducted to compare the in vivo uptake of 11C-methionine and 18F-FDG. Multiple focal cardiac inflammatory lesions were histologically identified in myosin-immunized rats, whereas no cardiac lesions were observed in the controls. Autoradiographic images clearly showed a high-density accumulation of 14C-methionine in inflammatory lesions of EAM rats, whereas no significant uptake was observed in the control animals. 14C-methionine uptake was significantly higher in inflammatory lesions than in remote noninflammatory areas and control rat hearts. The distribution of 14C-methionine correlated well with that of 18F-FDG and with macrophage density. The contrast between inflammatory and noninflammatory areas was higher for 18F-FDG than for 14C-methionine (3.45 ± 0.68 vs. 2.07 ± 0.21, respectively; P < 0.05). In the PET imaging study, the regional 11C-methionine uptake (percentage injected dose per cubic centimeter) observed in EAM rats was significantly higher than the values obtained for control animals (0.64 ± 0.09 vs. 0.28 ± 0.02, respectively; P < 0.001). A good positive correlation between 11C-methionine and 18F-FDG uptake was found. In a rat model of autoimmune myocarditis, we demonstrated the colocalization of radiolabeled methionine accumulation with 18F-FDG uptake in histologically proven inflammatory lesions. These data suggest that 11C-methionine might represent a promising candidate for the noninvasive detection and monitoring of myocarditis.

Molecular imaging of 1p/19q deletion in oligodendroglial tumours with 11C-methionine positron emission tomography

ObjectiveChromosome 1p/19q deletion is an established prognostic and predictive marker in the WHO grade III oligodendroglial tumours (OT). To estimate the genetic status preoperatively, the authors investigated the correlation between...

Use of 11C-methionine PET parametric response map for monitoring WT1 immunotherapy response in recurrent malignant glioma

Immunotherapy targeting the Wilms tumor 1 (WT1) gene product is a promising treatment modality for patients with malignant gliomas, and there have been reports of encouraging results. It has become clear, however, that Gd-enhanced MR imaging does not reflect prognosis, thereby necessitating a more robust imaging evaluation system for monitoring response to WT1 immunotherapy. To meet this demand, the authors performed a voxel-wise parametric response map (PRM) analysis of (11)C-methionine PET (MET-PET) in WT1 immunotherapy and compared the data with the overall survival after initiation of WT1 immunotherapy (OS(WT1)). Fourteen patients with recurrent malignant glioma were included in the study, and OS(WT1) was compared with: 1) volume and length change in the contrast area of the tumor on Gd-enhanced MR images; 2) change in maximum uptake of (11)C-methionine; and 3) a more detailed voxel-wise PRM analysis of MET-PET pre- and post-WT1 immunotherapy. The PRM analysis was able to identify the following 3 areas within the tumor core: 1) area with no change in (11)C-methionine uptake pre- and posttreatment; 2) area with increased (11)C-methionine uptake posttreatment (PRM(+MET)); and 3) area with decreased (11)C-methionine uptake posttreatment. While the results of Gd-enhanced MR imaging volumetric and conventional MET-PET analysis did not correlate with OS(WT1) (p = 0.270 for Gd-enhanced MR imaging length, p = 0.960 for Gd-enhanced MR imaging volume, and p = 0.110 for MET-PET), the percentage of PRM(+MET) area showed excellent correlation (p = 0.008) with OS(WT1). This study describes the limited value of Gd-enhanced MR imaging and highlights the potential of voxel-wise PRM analysis of MET-PET for monitoring treatment response in immunotherapy for malignant gliomas. Clinical trial registration no.: UMIN000002001.

Discrimination between low-grade oligodendrogliomas and diffuse astrocytoma with the aid of 11C-methionine positron emission tomography

The diagnostic usefulness of (11)C-methionine PET scans in gliomas is still controversial. The authors investigated the clinical significance of (11)C-methionine PET findings in preoperative diagnosis of histological type and grade. The tissue uptake of (11)C-methionine was assessed using PET in 70 patients with histologically confirmed intracerebral gliomas. The ratio of maximum standard uptake values in tumor areas to the mean standard uptake values in the contralateral normal brain tissue (tumor/normal tissue [T/N] ratio) was calculated and correlated with tumor type, histological grade, contrast enhancement on MR imaging, Ki 67 labeling index, and 1p/19q status. The T/N ratio was significantly increased as tumor grade advanced in astrocytic tumors (WHO Grade II vs Grade III, p = 0.0011; Grade III vs Grade IV, p = 0.0007). Among Grade II gliomas, the mean T/N ratio was significantly higher in oligodendroglial tumors than in diffuse astrocytomas (DAs) (p < 0.0001). All T/N ratios for oligodendroglial tumors were ≥ 1.46, and those for DA were consistently < 1.46, with the exception of 2 cases of gemistocytic astrocytoma. The Ki 67 labeling index significantly correlated with T/N ratio in astrocytic tumors, but not in oligodendrogliomas. Oligodendroglial tumors without 1p/19q deletion had a significantly higher T/N ratio than those with the codeletion. In combination with Gd-enhanced MR imaging, 67% of nonenhanced tumors with a T/N ratio of ≥ 1.46 were proved to be Grade II oligodendrogliomas. These results clearly show that (11)C-methionine PET T/N ratios in Grade II oligodendrogliomas were higher than those in DAs independently of their proliferative activity. This information contributes to preoperative differential diagnoses of histological type, especially in suspected low-grade gliomas.

Correlation of microvascular fractal dimension with positron emission tomography [ 11C]-methionine uptake in glioblastoma multiforme: Preliminary findings

Neuroradiological and metabolic imaging is a fundamental diagnostic procedure in the assessment of patients with primary and metastatic brain tumors. The correlation between objective parameters capable of quantifying the neoplastic angioarchitecture and imaging data may improve our understanding of the underlying physiopathology and make it possible to evaluate treatment efficacy in brain tumors. Only a few studies have so far correlated the quantitative parameters measuring the neovascularity of brain tumors with the metabolic profiles measured by means of amino acid uptake in positron emission tomography (PET) scans. Fractal geometry offers new mathematical tools for the description and quantification of complex anatomical systems, including microvascularity. In this study, we evaluated the microvascular network complexity of six cases of human glioblastoma multiforme quantifying the surface fractal dimension on CD34 immunostained specimens. The microvascular fractal dimension was estimated by applying the box-counting algorithm. As the fractal dimension depends on the density, size and shape of the vessels, and their distribution pattern, we defined it as an index of the whole complexity of microvascular architecture and compared it with the uptake of 11C-methionine (MET) assessed by PET. The different fractal dimension values observed showed that the same histological category of brain tumor had different microvascular network architectures. Fractal dimension ranged between 1.19 and 1.77 (mean: 1.415 ± 0.225), and the uptake of 11C-methionine ranged between 1.30 and 5.30. A statistically significant direct correlation between the microvascular fractal dimension and the uptake of 11C-methionine ( p = 0.02) was found. Our preliminary findings indicate that that vascularity (estimated on the histologic specimens by means of the fractal dimension) and 11C-methionine uptake (assessed by PET) closely correlate in glioblastoma multiforme and that microvascular fractal dimension can be a useful parameter to objectively describe and quantify the geometrical complexity of the microangioarchitecture in glioblastoma multiforme.

Non-FDG PET in the practice of oncology

Fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) is utilized in more than 90% of cancers in staging, re-staging, assessing therapy response and during the follow-up. However, not all tumors show significant increase of metabolic activity on FDG-PET imaging. This is particularly true for prostate cancer, neuroendocrine tumors and hepatic tumors. In this review we have considered those already used for clinical applications such as 11C- and 18F-Choline, 11C-Methionine and 18F-FET, 18F-DOPA, 68Ga-DOTA-somatostatine analogues, 11C-Acetate and 18F-FLT. Choline presents a high affinity for malignant prostate tissue, even if low grade. Choline can be labeled with either 11C or 18F, the former being the preference due to lower urinary excretion and patients exposure. The latter is more useful for possible distribution to centers lacking in on-site cyclotron. Methionine is needed for protein synthesis and tumor cells require an external supply of methionine. These tracers have primarily been used for imaging of CNS neoplasms. The most appropriate indication is when conventional imaging procedures do not distinguish between edema, fibrosis or necrosis and disease relapse. In addition, the uptake of 11C-Methionine is proportional to the tumor grade and, therefore, the maximum small unilamellar vesicles (SUV) inside the brain mass before therapy is somehow considered a prognostic value. Neuroendocrine tumors (carcinoids, pheocromocytoma, neuroblastoma, medullary thyroid cancer, microcytoma, carotid glomus tumors, and melanoma) demonstrate an increased activity of L-DOPA decarboxylase, and hence they show a high uptake of 18FDOPA. For the study of NETs, 68Ga-DOTA-TOC/DOTA-NOC has been introduced as PET tracer. This compound for PET imaging has a high affinity for sst2 and sst5 and has been used in the detection of NETs in preliminary studies; 68Ga-DOTA-NOC PET is useful before metabolic radiotherapy in order to evaluate the biodistribution of the therapeutic compound; 18F-FLT is a specific marker of cell proliferation and the most important field of application of FLT is lung cancer. Other tracers are used in PET utilized as markers of hypoxia inside big neoplastic masses include 18F-MISO, 64Cu-ATSM, 18F-EF5, which highlight the presence of hypoxic areas are useful for patients that must be treated with radiotherapy.