39 research outputs found
In silico approach for the definition of radiomirnomic signatures for breast cancer differential diagnosis
No full textPersonalized medicine relies on the integration and consideration of specific characteristics of the patient, such as tumor phenotypic and genotypic profiling. BACKGROUND: Radiogenomics aim to integrate phenotypes from tumor imaging data with genomic data to discover genetic mechanisms underlying tumor development and phenotype. METHODS: We describe a computational approach that correlates phenotype from magnetic resonance imaging (MRI) of breast cancer (BC) lesions with microRNAs (miRNAs), mRNAs, and regulatory networks, developing a radiomiRNomic map. We validated our approach to the relationships between MRI and miRNA expression data derived from BC patients. We obtained 16 radiomic features quantifying the tumor phenotype. We integrated the features with miRNAs regulating a network of pathways specific for a distinct BC subtype. RESULTS: We found six miRNAs correlated with imaging features in Luminal A (miR-1537, -205, -335, -337, -452, and -99a), seven miRNAs (miR-142, -155, -190, -190b, -1910, -3617, and -429) in HER2+, and two miRNAs (miR-135b and -365-2) in Basal subtype. We demonstrate that the combination of correlated miRNAs and imaging features have better classification power of Luminal A versus the different BC subtypes than using miRNAs or imaging alone. CONCLUSION: Our computational approach could be used to identify new radiomiRNomic profiles of multi-omics biomarkers for BC differential diagnosis and prognosis
Metabolic impact of partial volume correction of [18F]FDG PET-CT oncological studies on the assessment of tumor response to treatment
No full textThe aim of this work is to evaluate the metabolic impact of Partial Volume Correction (PVC) on the measurement of the Standard Uptake Value (SUV) from [18F]FDG PET-CT oncological studies for treatment monitoring purpose
Prognostic Value of 18 F-Fluorocholine PET Parameters in Metastatic Castrate-Resistant Prostate Cancer Patients Treated with Docetaxel
No full textBackground and Aim. The availability of new treatments for metastatic castrate-resistant prostate cancer (mCRPC) patients increases the need for reliable biomarkers to help clinicians to choose the better sequence strategy. The aim of the present retrospective and observational work is to investigate the prognostic value of 18 F-fluorocholine ( 18 F-FCH) positron emission tomography (PET) parameters in mCRPC. Materials and Methods. Between March 2013 and August 2016, 29 patients with mCRPC were included. They all received three-weekly docetaxel after androgen deprivation therapy, and they underwent 18 F-FCH PET/computed tomography (CT) before and after the therapy. Semi-quantitative indices such as maximum standardized uptake value (SUV max ), mean standardized uptake value (SUV mean ) with partial volume effect (PVC-SUV) correction, metabolically active tumour volume (MATV), and total lesion activity (TLA) with partial volume effect (PVC-TLA) correction were measured both in pre-treatment and post-treatment 18 F-FCH PET/CT scans for each lesion. Whole-body indices were calculated as sum of values measured for each lesion (SSUV max , SPVC-SUV, SMATV, and STLA). Progression-free survival (PFS) and overall survival (OS) were considered as clinical endpoints. Univariate and multivariate hazard ratios for whole-body 18 F-FCH PET indices were performed, and p<0.05 was considered as significant. Results. Cox regression analysis showed a statistically significant correlation between PFS, SMATV, and STLA. No correlations between OS and 18 F-FCH PET parameters were defined probably due to the small sample size. Conclusions. Semi-quantitative indices such as SMATV and STLA at baseline have a prognostic role in patients treated with docetaxel for mCRPC, suggesting a potential role of 18 F-FCH PET/CT imaging in clinical decision-making
Prognostic Value of 18 F-Fluorocholine PET Parameters in Metastatic Castrate-Resistant Prostate Cancer Patients Treated with Docetaxel
No full textBackground and Aim. The availability of new treatments for metastatic castrate-resistant prostate cancer (mCRPC) patients increases the need for reliable biomarkers to help clinicians to choose the better sequence strategy. The aim of the present retrospective and observational work is to investigate the prognostic value of F-18-fluorocholine (F-18-FCH) positron emission tomography (PET) parameters in mCRPC. Materials and Methods. Between March 2013 and August 2016, 29 patients with mCRPC were included. They all received three-weekly docetaxel after androgen deprivation therapy, and they underwent F-18-FCH PET/computed tomography (CT) before and after the therapy. Semi-quantitative indices such as maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean) with partial volume effect (PVC-SUV) correction, metabolically active tumour volume (MATV), and total lesion activity (TLA) with partial volume effect (PVC-TLA) correction were measured both in pre-treatment and post-treatment F-18-FCH PET/CT scans for each lesion. Whole-body indices were calculated as sum of values measured for each lesion (SSUVmax, SPVC-SUV, SMATV, and STLA). Progression-free survival (PFS) and overall survival (OS) were considered as clinical endpoints. Univariate and multivariate hazard ratios for whole-body F-18-FCH PET indices were performed, and p<0.05 was considered as significant. Results. Cox regression analysis showed a statistically significant correlation between PFS, SMATV, and STLA. No correlations between OS and F-18-FCH PET parameters were defined probably due to the small sample size. Conclusions. Semi-quantitative indices such as SMATV and STLA at baseline have a prognostic role in patients treated with docetaxel for mCRPC, suggesting a potential role of F-18-FCH PET/CT imaging in clinical decision-making
Study of reliability of TLDs for the photon dose mapping in reactor neutron fields for BNCT
No full textPhoton dose measurements in radiation fields having the proper characteristics for boron neutron capture therapy (BNCT) present several troubles. The thermal neutron flux is very high and produces a significant contribution to the response of most dosimeters. The consistency of
photon dose measurements with CaF2:Tm and LiF:Mg, Ti thermoluminescent dosimeters has been studied. A method is described for obtaining the gamma dose with TLD-700 and some results are presented to test its reliability
Gel dosimetry measurements and Monte Carlo modeling for external radiotherapy photon beams : comparison with a treatment planning system dose distribution
No full textGel dosimetry has proved to be a useful support to determine absorbed dose distributions in radiotherapy as well as to validate treatment plans. Gel dosimetry allows dose imaging and is particularly helpful for non-uniform dose distribution measurements, as may occur when multiple-field irradiation techniques are employed. In this work we report gel-dosimetry measurements and Monte Carlo (PENELOPE®) calculations for the dose distribution inside a tissue-equivalent phantom exposed to a typical multiple-field irradiation. Irradiations were performed with a 10 MV photon beam from a Varian® Clinac 18 accelerator. The employed dosimeters consisted of layers of Fricke Xylenol Orange radiochromic gel. The method for absorbed dose imaging was based on analysis of visible light transmittance, usually detected by means of a CCD camera. With the aim of finding a simple method for light transmittance image acquisition, a commercial flatbed-like scanner was employed. The experimental and simulated dose distributions have been compared with those calculated with a commercially available treatment planning system, showing a reasonable agreement
Response to chemotherapy in gastric adenocarcinoma with diffusion-weighted MRI and 18F-FDG-PET/CT: Correlation of apparent diffusion coefficient and partial volume corrected standardized uptake value with histological tumor regression grade
No full textPURPOSE:To assess whether changes in diffusion-weighted MRI (DW-MRI) and (18) F-fluoro-2-deoxyglucose positron emission tomography/computed tomography ((18) F-FDG PET/CT), correlate with treatment response to neoadjuvant therapy (NT), as expressed by tumor regression grade (TRG), from locally advanced gastric adenocarcinoma (GA).MATERIALS AND METHODS:Seventeen patients underwent both DW-MRI and (18) F-FDG-PET/CT scans before and after the end of NT. Apparent diffusion coefficient (ADC) and mean standardized uptake value (SUV) corrected for partial volume effect (PVC-SUVBW-mean ) were evaluated and compared with histopathological TRG.RESULTS:Pre- and post-NT and percentage changes for ADC and PVC-SUVBW-mean were assessed. Post-NT ADC and ΔADC showed a significant inverse correlation with TRG (r = -0.71; P = 0.0011 and r = -0.78; P = 0.00020, respectively) and significant differences in their mean values were found between responders (TRG 1-2-3) and nonresponders (TRG 4-5) (P = 0.0009; P = 0.000082, respectively). No correlations with TRG were found for pre-NT ADC and for all PVC-SUVBW-mean values as well as between ΔADC and Δ PVC-SUVBW-mean .CONCLUSION:DW-MRI seems more accurate than (18) F-FDG-PET/CT and ADC modifications may represent a reproducible tool to assess tumor response for GA.PurposeTo assess whether changes in diffusion-weighted MRI (DW-MRI) and 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT), correlate with treatment response to neoadjuvant therapy (NT), as expressed by tumor regression grade (TRG), from locally advanced gastric adenocarcinoma (GA).Materials and MethodsSeventeen patients underwent both DW-MRI and 18F-FDG-PET/CT scans before and after the end of NT. Apparent diffusion coefficient (ADC) and mean standardized uptake value (SUV) corrected for partial volume effect (PVC-SUVBW-mean) were evaluated and compared with histopathological TRG.ResultsPre- and post-NT and percentage changes for ADC and PVC-SUVBW-mean were assessed. Post-NT ADC and ΔADC showed a significant inverse correlation with TRG (r = −0.71; P = 0.0011 and r = −0.78; P = 0.00020, respectively) and significant differences in their mean values were found between responders (TRG 1–2-3) and nonresponders (TRG 4–5) (P = 0.0009; P = 0.000082, respectively). No correlations with TRG were found for pre-NT ADC and for all PVC-SUVBW-mean values as well as between ΔADC and Δ PVC-SUVBW-mean.ConclusionDW-MRI seems more accurate than 18F-FDG-PET/CT and ADC modifications may represent a reproducible tool to assess tumor response for G
Effects of functional type and angular configuration on reflectance anisotropy of aquatic vegetation in ultra-high resolution hyperspectral imagery
No full textImaging spectroscopy and lightweight unmanned aerial vehicles (UAVs) have revolutionized remote sensing of vegetation, by providing high spectral and spatial resolution data. Comprehensive wetland monitoring should be based on reliable mapping of biophysical aquatic vegetation parameters, which in turn requires low bias in measured spectra, e.g. minimization of reflectance anisotropy. This study aims to quantitatively investigate how sensor scan direction and solar zenith angle (SZA) affect vegetation spectra over two dominant aquatic plants, Phragmites australis and Nuphar lutea, representing different functional types (i.e. emergent and floating) with divergent canopy structure and affinity with water, using data collected with a hyperspectral (400–1000 nm range) push-broom sensor mounted on a UAV. Anisotropy factor (ANIF), mean reflectance scatterplots and regression analysis were used for assessing the magnitude of spectral anisotropy at both pseudo-leaf and canopy scales. Our findings showed more accentuated anisotropic behaviour in the visible than near-infrared domain at SZA < 60° as the scan direction approaches that of solar principal plane. The increase in reflectance in near-forward direction affects the spectra of floating-leaved N. lutea at both leaf and canopy scales, suggesting the presence of water (as a film over leaves or as canopy background) as a likely anisotropy driver. Backward hotspot is evident in canopy spectra of emergent P. australis, with driving mechanisms similar to terrestrial species (i.e. shadow-hiding). At SZA > 60°, reflectance anisotropy appears to be negligible, independent of functional type and scan direction. This research underscores the importance of considering sun-target-sensor geometry in remote sensing studies on aquatic vegetation
New positron emission tomography derived parameters as predictive factors for recurrence in resected stage I non-small cell lung cancer
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