Currently, positron emission tomography (PET) is the standard imaging modality in neuro-oncology for gliomas and metastatic lesions. The experience of PET application in meningiomas, the most frequent primary CNS neoplasms, is much less, and the interpretation of the study results has a number of differences. The aim of the study was to evaluate the possibility and peculiarities of PET application in meningiomas based on our own clinical experience and literature review. The study included 70 patients with 77 meningiomas who underwent PET/CT with C-11-methionine. The mean age at the time of examination was 57.4 years (19-86 years). The main evaluation parameter, the tumor-to-brain ratio (TBR) of C-11-methionine (C-11-MET) averaged 3.13 (1.00- 10.66). Meningiomas were characterized by high C-11-MET TBR, with 89.6% of cases having TBR greater than 1.5. In histologically verified WHO grade 1, 2, and 3 meningiomas, the median TBR was 4.06 [3.04, 4.57], 2.32 [2.12, 3.69], and 4.29 [2.60, 5.10] and did not differ significantly between groups. Meanwhile, in histologically unresectable slow- growing or non-growing incidental meningiomas, TBR of C-11-MET was significantly lower than in WHO grade 1 and 3 meningiomas. There was no significant difference in the accumulation index between irradiated meningiomas with tumor growth control (3.81 [2.97, 3.98]) and recurrence (3.62 [2.60, 4.30]). When irradiated and non-irradiated meningiomas of WHO grade 1, 2 and 3, as well as the combined group of grade 1-3 tumors were compared, no significant differences in C-11-MET TBR were found. The use of PET/CT in meningiomas has a number of important features. Meningiomas are characterized by high TBR of C-11-MET. According to our data PET/CT with C-11-MET does not allow differentiating between meningiomas of different degrees of malignancy - 1, 2 or 3 according to WHO. With effective radiotherapy, meningiomas show partial reduction of TBR or remain stable. Even with prolonged growth control after radiation treatment, meningiomas may still have high TBR of C-11-MET. When comparing growing and stable meningiomas, irradiated and non-irradiated tumors, no significant differences in TBR of( 11)C-MET are found.

Mutations of isocitrate dehydrogenase (IDH) have important prognostic significance for patients with glial brain tumor. The method of proton MR spectroscopy makes it possible to non-invasively determine the metabolic properties of the tumor tissue at the preoperative stage. The aim of this work was to study the possibility of determining the IDH status, by using magnetic resonance spectroscopy (MRS) to detect the 2-hydroxyglutarate (2HG), a metabolic product of the IDH enzyme. We examined 33 patients with glial tumors varying degrees of malignancy (Gr. 2–4), followed by identification of IDH mutations. IDH mutation identified in 20 cases, according to proton magnetic resonance spectroscopy, was confirmed by immunohistochemistry. Peak of 2HG did not detect in 13 cases on the MR spectrum, and the analysis for IDH did not reveal mutations. Using of proton magnetic resonance spectroscopy showed a high sensitivity of this technique in predicting the mutational status of glial brain tumors, which makes this method an important in preoperative diagnostics.

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_FLAIR, V_PET and V_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_PET=24.3 cm3, Se 67%, Sp 60%, AUC 0.65; V_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_PET=8.06 cm3, Se 91%, Sp 35%, AUC 0.66; V_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.

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

Currently, positron emission tomography (PET) is the standard imaging modality in neuro-oncology for gliomas and metastatic lesions. The experience of PET application in meningiomas, the most frequent primary CNS neoplasms, is much less, and the interpretation of the study results has a number of differences. The aim of the study was to evaluate the possibility and peculiarities of PET application in meningiomas based on our own clinical experience and literature review. The study included 70 patients with 77 meningiomas who underwent PET/CT with 11C-methionine. The mean age at the time of examination was 57.4 years (19–86 years). The main evaluation parameter, the tumor-to-brain ratio (TBR) of 11C-methionine (11C–MET) averaged 3.13 (1.00–10.66). Meningiomas were characterized by high 11C–MET TBR, with 89.6% of cases having TBR greater than 1.5. In histologically verified WHO grade 1, 2, and 3 meningiomas, the median TBR was 4.06 [3.04, 4.57], 2.32 [2.12, 3.69], and 4.29 [2.60, 5.10] and did not differ significantly between groups. Meanwhile, in histologically unresectable slow-growing or non-growing incidental meningiomas, TBR of 11C–MET was significantly lower than in WHO grade 1 and 3 meningiomas. There was no significant difference in the accumulation index between irradiated meningiomas with tumor growth control (3.81 [2.97, 3.98]) and recurrence (3.62 [2.60, 4.30]). When irradiated and non-irradiated meningiomas of WHO grade 1, 2 and 3, as well as the combined group of grade 1–3 tumors were compared, no significant differences in 11C–MET TBR were found. The use of PET/CT in meningiomas has a number of important features. Meningiomas are characterized by high TBR of 11C–MET. According to our data PET/CT with 11C–MET does not allow differentiating between meningiomas of different degrees of malignancy – 1, 2 or 3 according to WHO. With effective radiotherapy, meningiomas show partial reduction of TBR or remain stable. Even with prolonged growth control after radiation treatment, meningiomas may still have high TBR of 11C–MET. When comparing growing and stable meningiomas, irradiated and non-irradiated tumors, no significant differences in TBR of 11C–MET are found.

To study 11C-methionine (MET) metabolism in gliomas using CNS tumor biobank imaging data.

Glioblastoma (GB) is an extremely heterogeneous tumor, which is caused by genomic instability, high growth rate, and neovascularization. Molecular and genetic characteristics of GB play a major role in the prognosis of the disease, which is reflected in the new WHO classification of CNS tumors from 2021. Purpose of this research is comparison MRI parameters (ADC CBF), metabolic activity on 11C-MET PET/СT with glioblastoma genetic profile. 40 patients (age 55±12 years, sex M/F = 31/9) with newly diagnosed GB were examined by MRI with assessment of diffusion parameters (ADCmin) and ASL perfusion (CBFmax) and 11С-МЕТ PET/CT with the calculation of tumor to normal index (METmax). Since these VOI (1cm3) did not always coincide, it was decided to measure all parameters in each VOI on all image maps (PMOD automatic contour transfer). A total of 9 measurements were obtained for each patient: METmax, METcbf, METadc; ADCmin, ADCmet, ADCcbf; CBFmax, CBFmet, CBFadc. Comparative and correlation analysis was carried out both in the total GB group and separately in the groups MGMT+/and EGFR+/and different Ki67 levels (cut-off 20%). In results 45% of patients had CBFmax, ADCmin and METmax mismatch. Significant correlations were found in the METmax VOI between METmaxADCmet (Rs = -0.37) and METcbfADCcbf (Rs = -0.05). CBFmax and CBFmet correlated with Ki67 (Rs = 0.38 and Rs = 0.48, respectively) and increased in Ki67 20% GB group. GB genetic subgroup analysis showed: MGMT+ had significantly higher ADCmin1.01 (10-3 mm2/sec), Se = 78%, Sp = 74%, AUC = 0.77, it means that cells were more tightly packed. In METmax VOI, METmax was negatively correlated with ADCmet (Rs = -0.72) and CBFmet was positively correlated with Ki-67 (Rs = 0.89); EGFR+ tumors had significantly higher METmax 3.29 (Se = 88%, Sp = 70%, AUC = 0.82), that was negatively correlated with ADCmet (Rs = -0.85). In case when Ki67 20% GB demonstrated significantly higher CBFmax 108.177ml/100/min (Se = 70%, Sp = 94%, AUC 0.75) and a strong negative correlation between METmax and ADCmet, (Rs = -0,65) in METmax VOI. Our study shown that CBFmax, ADCmin and METmax localization coincide in 45% of cases, which proves the presence of variety in the structure and functional activity of different areas of GB. The correlation of MGMT methylation and ADC (ADCmin 1.01 (10-3 mm2/sec), Se = 78%, Sp = 74%, AUC = 0.77) confirms the recent studies results of this tumor subtype lower needs of the new membranes construction, that’s due to the inhibition of the mechanism of the DNA repair system. EGFR amplification presence in our patient sample was associated with a significant higher MET metabolism (МЕTmax 3.29, Se = 88%, Sp = 70%, AUC = 0.82) and correlated with height level of Ki67 (Rs = -0.85), confirming the fact of GB cells amino acids increased consumption for membrane synthesis. The obtained correlations MET with ADC and the absence of those with CBF, confirms the dependence glioma methionine metabolism of the new cell membranes building, rather than on neovascularization. Revealed mismatch of MRI and PET/CT parameters confirmed GB structure heterogeneity phenomenon, as well as their significant differences in various genetic status GB subgroups.

The future of contemporary neuroimaging does not solely lie in novel image-capturing technologies, but also in better methods for extraction of useful information from these images. Scientists see great promise in radiomics, i.e. the methodology for analysis of multiple features in medical image. However, there are certain issues in this field impairing reproducibility of results. One such issue is no standards in establishing the regions of interest.OBJECTIVE:To introduce a standardized method for identification of regions of interest when analyzing MR images using radiomics; to test the hypothesis that this approach is effective for distinguishing different histological types of gliomas.MATERIAL AND METHODS:We analyzed preoperative MR data in 83 adults with various gliomas (WHO classification, 2016), i.e. oligodendroglioma, anaplastic oligodendroglioma, anaplastic astrocytoma, and glioblastoma. Radiomic features were computed for T1, T1-enhanced, T2 and T2-FLAIR modalities in four standardized volumetric regions of interest by 356 voxels (46.93 mm3): 1) contrast enhancement; 2) edema-infiltration; 3) area adjacent to edema-infiltration; 4) reference area in contralateral hemisphere. Subsequently, mathematical models were trained to classify MR-images of glioma depending on histological type and quantitative features.RESULTS:Mean accuracy of differential diagnosis of 4 histological types of gliomas in experiments with machine learning was 81.6%, mean accuracy of identification of tumor types - from 94.1% to 99.5%. The best results were obtained using support vector machines and random forest model.CONCLUSION:In a pilot study, the proposed standardization of regions of interest demonstrated high effectiveness for MR-based differential diagnosis of oligodendroglioma, anaplastic oligodendroglioma, anaplastic astrocytoma and glioblastoma. There are grounds for applying and improving this methodology in further studies.

Modern methodology of PET/CT quantitative analysis in patients with glioblastomas is not strictly standardized in clinic settings and does not exclude the influence of the human factor.Methods of radiomics may facilitate unification, and improve objectivity and efficiency of the medical image analysis.The aim of the study is to evaluate the potential of radiomics in the analysis of PET/CT glioblastoma images identifying the relationship between the radiomic features and the 11 С-methionine tumor-to-normal brain uptake ratio (TNR) determined by an expert in routine.Materials and Methods.PET/CT data (2018-2020) from 40 patients (average age was 55±12 years; 77.5% were males) with a histologically confirmed diagnosis of "glioblastoma" were included in the analysis.TNR was calculated as a ratio of the standardized uptake value of 11 C-methionine measured in the tumor and intact tissue.Calculation of radiomic features for each PET was performed in the specified volumetric region of interest, capturing the tumor with the surrounding tissues.The relationship between TNR and the radiomic features was determined using the linear regression model.Predictors were included in the model following correlation analysis and LASSO regularization.The experiment with machine learning was repeated 300 times, splitting the training (70%) and test (30%) subsets randomly.The model quality metrics and predictor significance obtained in 300 tests were summarized.Results.Of 412 PET/CT radiomic parameters significantly correlated with TNR (p<0.05), the regularization procedure left no more than 30 in each model (the median number of predictors was 9 [7; 13]).The experiment has demonstrated a non-random linear correlation (the Spearman correlation coefficient was 0.58 [0.43; 0.74]) between TNR and separate radiomic features, primarily fractal dimensions, characterizing the geometrical properties of the image. Conclusion.Radiomics enabled an objective determination of PET/CT image texture features reflecting the biological activity of glioblastomas.Despite the existing limitations in the application, the first results provide a good perspective of these methods in neurooncology.

The aim of this study was to evaluate average 11 C-methionine uptake for grade II (anaplastic) gliomas in a large cohort, as well as relations between MRI and PET characteristics and their unfluence on overall and progression-free survival. Materials and methods . The study was based upon 78 patients with supratentorial tumors, among them 48 with anaplastic astrocytoma (AA) and 30 with anaplastic oligodendroglioma (AO). ALL patients underwent PET-CT with 11 C-methionine and MRI study (Т1, Т2, Т2-FLAIR, DWI и 3D Т1+Gd regimes). Tumor removal was performed in 71 cases, stereotactic biopsy in 8 patients. Tumor specimen were assessed by neuropatomorphologists and IDH1-status and 1p/19q co-deletion were evaluated. Study results . AA IDH − tumors demonstrated statistically significant bigger metabolic volume and radiotracer uptake comparing with AA IDH + . Moreover, AA IDH − characterized by higher fractional MET uptake. The smallest tumors (by MRI) were AOs, meanwhile their fractional contrast enhancement was higher than for AAs. AOs were also known as tumors with minimal difference between MRI and PET-CT volume. MET uptake decreased in a row АА IDH − – АОД – AA IDH + , but the difference has not reached statistical significance. For wild-type AAs metabolic volume correlated with OS and PFS, meanwhile for IDH-mutant AAs tumor volume (measured by MRI) correlated only with PFS. Conclusion . Present study based on the largest cohort of patients with anaplastic gliomas who underwent both MRI and PET with 11 C-methionine. It turned out, that unlike grade II oligodendogliomas, AOs do not always demonstrate higher than their astrocytic counterparts MET uptake levels.

The most important objective of modern neuroimaging is comparison of data on genotype and phenotype of brain gliomas. Radiogenomics as a new branch of science is devoted to searching for such relationships based on MRI and PET/CT parameters. The 2021 WHO classification of tumors of the central nervous system poses the most important tasks for physicians in assessment of biological behavior of tumors and their response to combined treatment. The review demonstrates the possibilities and prospects of preoperative MRI and PET/CT with amino acids in assessing the genetic profile of brain gliomas.

OBJECTIVE:To evaluate the possibilities of dynamic preoperative 11C-methionine (MET) PET/CT in differential diagnosis of various types of brain gliomas in adults.MATERIAL AND METHODS:The study included 74 patients aged 48±14 years with supratentorial gliomas: Grade IV - glioblastoma (GB, n=33), Grade III - anaplastic oligodendroglioma (AOD, n=10) and anaplastic astrocytoma (AA, n=12), Grade II - diffuse astrocytoma (DA, n=13) and oligodendroglioma (OD, n=6). All patients underwent standard MRI and dynamic MET PET/CT within 20 minutes after intravenous injection of radiopharmaceutical. Then, we compared MRI and PET/CT data and comprehensively analyzed the early stages of time-activity curve using 2 parameters: the first pass peak (FPP) and the first peak of maximum uptake (Pmax).RESULTS:We have significantly distinguished high-grade tumors (GB and AA+AOD) and certain benign gliomas (DA and OD) (p<0.05). AUC was over 0.7 and 0.8 for FPP and Pmax in differential diagnosis of various gliomas, respectively. We found that difficulties in differential diagnosis of gliomas arise mainly if oligodendrogliomas are included in the control group.CONCLUSION:Dynamic PET/CT with analysis of FPP and Pmax increases specificity of differential diagnosis of various gliomas compared to standard static imaging. These data are valuable for choice of optimal treatment strategy, as well as fundamental research of metabolic processes and vascularization of various tumors.

ПЭТ/КТ С 11С-МЕТИОНИНОМ И 18F-ФТОРДЕЗОКСИГЛЮКОЗОЙ В ИЗУЧЕНИИ ГЕТЕРОГЕННОСТИ ГЛИОМ ГОЛОВНОГО МОЗГАВихрова Н

OBJECTIVE:To study energy metabolism in glial tumors using dynamic MR spectroscopy and 18F-FDG PET/CT.MATERIAL AND METHODS:The study included 19 patients (9 women and 10 men) with newly diagnosed supratentorial glial tumors WHO Grade I-IV (diffuse astrocytoma - 4 cases, oligodendroglioma - 4 cases, anaplastic astrocytoma - 5 cases, glioblastoma - 6 cases). All patients underwent examination and surgical treatment at the Burdenko Neurosurgery Center. Dynamic MR spectroscopy and 18F-FDG PET/CT were applied in each patient.RESULTS:We found multiple correlations between the ratio of bioorganic phosphate peaks and parameters of glucose uptake by tumor tissue. These relationships were more significant in patients with high-grade tumors: positive significant correlation between SUVtumor and PME/PCr ratio (RS=0.75, p=0.01), T/Nmix and βATP/Pi ratio (Rs=0.76, p=0.02), SUVpeaktumor and aATP/Pi ratio (RS=0.77, p=0.008). Moreover, there were negative correlations between SUVtumor and PCr/bATP ratio (RS= -0.66, p=0.05), T/Nmix and PDE/bATP ratio (RS= -0.83, p=0.006), SUVpeaktumor and PDE/aATP ratio (RS= -0.76, p=0.009).CONCLUSION:High-grade gliomas were characterized by higher glucose consumption, ATP release (intensification of energy metabolism) and faster cell membrane synthesis. These processes indicate enhanced proliferation of tumor cells (intensification of plastic metabolism).

Purpose. The aim of this prospective study, which included the analysis of data from 52 patients with primary brain gliomas, was to look for additional PET-CT biomarkers determined on the basis of the analysis of the first minute of dynamic PET scanning in order to increase the specificity and sensitivity of differential diagnosis of gliomas. 18F-FDG was administered simultaneously with the data collection began. Materials and methods. The study group included data of 52 patients, 27 men, 25 women, age 18-80 years, median 48 years + 12. Histologically, these were glioblastomas (n= 19), anaplastic astrocytomas (n=9), anaplastic oligodendrogliomas (n= 6), benign oligodendrogliomas (n= 6), and diffuse astrocytomas (n=9). Each patient underwent a standard brain MR- study (T2, T2-FLAIR, T1, 3D T1 with contrast enhancement). The selected patients then underwent PET-CT examination (Siemens Truepoint scanner, Siemens Medical Solutions, USA) with radiopharmaceutical 18F-FDG according to the dynamic protocol developed in the our department. Data collection started simultaneously with intravenous administration of radiotracer for the next 40 minutes. 34 frames of 6X10 sec, 6x20 sec, 6x30 sec, 4x60 sec and 12x150 sec were reconstructed. Results. Among the proposed new PET parameters, T/N60s (accumulation index averaged over the first 60 seconds after the administration of 18 F-FDG) turned out to be the most successful, which made it possible to statistically reliably separate glioblastomas from all other histological subtypes of gliomas. Thus, for glioblastomas, T/N60s = 1.6 ± 0.4, and for anaplastic oligodendrogliomas, it was 1.1 ± 0.2, p<0.01. Moreover, T/N60s made it possible to reliably differentiate not only Gr. II from gliomas Gr.III + Gr.IV, but also to differentiate glioblastomas from anaplastic astrocytomas (p<0.01) and glioblastomas from anaplastic and benign oligodendrogliomas (p<0.05 and p<0.01, respectively). All types of gliomas had an T/N60s>1.0, while its final accumulation could be lower than in intact tissue. A possible reason for this phenomenon may be tumor neoangiogenesis, which develops even in the case of low-grade gliomas. Conclusion. The use of the proposed technique for studying patients with brain gliomas and analyzing the data obtained with the new PET biomarkers significantly improves the quality of differential diagnosis of gliomas using 18F-FDG. It also allows reducing the study time for one patient without losing the specificity and sensitivity of diagnosis.

МУЛЬТИВОКСЕЛЬНАЯ 3D МАГНИТНО-РЕЗОНАНСНАЯ СПЕКТРОСКОПИЯ И ПОЗИТРОННО-ЭМИССИОННАЯ ТОМОГРАФИЯ С 11

Purpose of the study is investigation of the possibilities of Positron Emission Tomography - Computed Tomography (PET-CT) with different radiopharmaceuticals in non-invasive differential diagnosis of primary high grade gliomas. 18 patients, 11 with glioblastoma (GB) and 7 with anaplastic astrocytoma (AA), were examined before surgery with magnetic resonance imaging (MRI) and PET-CT with 11С-methionine (MET) and 18F-fluorodeoxyglucose (FDG). The analysis was carried out according to the standardized uptake value (SUV) in the tumor and healthy brain tissue, and tumor to normal (T/N) ratio. AA and GB groups are significantly different in T/N ratio for 11C-MET (1,62 ± 0,71 in AA versus 3,97 ±1,04 in GB, p < 0,001), and for 18F-FDG (0,64 ± 0,11 in AA versus 1,25 ± 0,66 in GB, p = 0,02). Levels of accumulation of 11C-MET and 18F-FDG in intact brain tissue correlate with each other (value of R2 = 0,61). The areas of high accumulation of two radiopharmaceuticals in the tumor stroma do not coincide. Our study demonstrated that the accumulation of 18F-FDG and 11C-methionine in HGG significantly depends on tumor grade. To improve practical value of this study patients with anaplastic oligodendrogliomas (Gr III), which are metabolically similar to GB, must be added to the comparison group.

Background. Breast cancer is the second most common cancer worldwide. Despite significant advances in breast cancer treatment, more than 50 % of patients develop recurrence following completion of treatment. If there is a suspicion of disease progression, the differential diagnosis of metastatic tumor and non-metastatic lesion using the standard imaging methods can be difficult. A modern approach to the detection and assessment of the extension of recurrent disease is individual evaluation of the biological characteristics of the tumor, including determination of the status of estrogen receptors with the goal of adequate treatment. PET/CT with 18F-fluoroestradiol in patients with hormone-dependent breast cancer can be used to determine the expression of estrogen receptors (RE) in tumor tissue and assess the presence of receptor-positive metastases throughout the body in a single study. Case description. We report the cases of 55-year-old and 57-year-old women with hormone-dependent breast cancer after standard treatment (surgery, radiation therapy and hormone therapy). During hormone therapy, lung lesions were detected in both patients. To assess the activity of these lesions, 18F-fluoroestradiol PET/CT was used. In the first case, a low uptake of 18F-FDG was observed. In the other case, no18F-FDG uptake was found. Given that both patients had hormone-dependent breast cancer, it was decided to perform PET/CT with 18F-fluoroestradiol (18F-FES) to evaluate the expression of ER. In the first case, the 18F-FES uptake was detected in all lesions that indicated the evidence of metastases. Histological examination confirmed the evidence of metastatic tumor. In the second case, no uptake of 18FFES was detected in the foci and the patient was followed-up for 6 months. Computed tomography showed decrease in the size of lesions.Conclusion. The use of 18F-FES PET/CT can be an important diagnostic tool for detection of disease progression in patients with hormone-dependent breast cancer. In case of detection of positive foci on 18F-FES PET/CT scans, hormone therapy for breast cancer can be administered without invasive procedures for verifying the diagnosis.

Renal cell carcinoma (RCC) is the most common primary tumor of the renal parenchyma. Venous involvement is one of the most important anatomic characteristics of tumor. It is known that venous spread influences the survival of patients with RCC. Tumor thrombosis of IVC in patients with renal cell carcinoma has been reported in 4–10 %. The reference standard for RCC with tumor thrombus remains surgical resection. The structure of thrombus determines some technical difficulties in the management of tumor. Spongeous thrombus correlate with higher risk of thrombus detachment during surgery resulting in PE. Therefore determination of IVC thrombus consistency is very important part of preoperative radiologic assessment of tumor in patients with RCC.

Renal cell carcinoma (RCC) is the most common primary tumor of the kidney; it accounts for approximately 3% of newly diagnosed cancers. The incidence of venous extension to the inferior vena cava (IVC) and renal vein in RCC is markedly increased recently mostly due to the advances in diagnostic modalities. Knowledge of the tumoral stage and determination of tumor thrombus extension at the time of diagnosis is essential for prognosis and surgical planning. Nowadays abdominal ultrasound (US), computed tomography (CT) and magnetic resonance (MR) scanning techniques are used for the detection and staging of RCC. In this study, the accuracy of recent diagnostic tools in determination of IVC thrombus is outlined. Also the role of positron emission tomography (PET) scanning is briefly addressed.