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Radiomics and artificial intelligence have the potential to become a valuable tool in clinical applications. Frequently, radiomic analyses through machine learning methods present issues caused by high dimensionality and multicollinearity, and redundant radiomic features are usually removed based on correlation analysis. We assessed the effect of preprocessing—in terms of voxel size resampling, discretization, and filtering—on correlation-based dimensionality reduction in radiomic features from cardiac T1 and T2 maps of patients with hypertrophic cardiomyopathy. For different combinations of preprocessing parameters, we performed a dimensionality reduction of radiomic features based on either Pearson's or Spearman's correlation coefficient, followed by the computation of the stability index. With varying resampling voxel size and discretization bin width, for both T1 and T2 maps, Pearson's and Spearman's dimensionality reduction produced a slightly different percentage of remaining radiomic features, with a relatively high stability index. For different filters, the remaining features' stability was instead relatively low. Overall, the percentage of eliminated radiomic features through correlation-based dimensionality reduction was more dependent on resampling voxel size and discretization bin width for textural features than for shape or first-order features. Notably, correlation-based dimensionality reduction was less sensitive to preprocessing when considering radiomic features from T2 compared with T1 maps. [ABSTRACT FROM AUTHOR]

Radiomics is emerging as a promising and useful tool in cardiac magnetic resonance (CMR) imaging applications. Accordingly, the purpose of this study was to investigate, for the first time, the effect of image resampling/discretization and filtering on radiomic features estimation from quantitative CMR T1 and T2 mapping. Specifically, T1 and T2 maps of 26 patients with hypertrophic cardiomyopathy (HCM) were used to estimate 98 radiomic features for 7 different resampling voxel sizes (at fixed bin width), 9 different bin widths (at fixed resampling voxel size), and 7 different spatial filters (at fixed resampling voxel size/bin width). While we found a remarkable dependence of myocardial radiomic features from T1 and T2 mapping on image filters, many radiomic features showed a limited sensitivity to resampling voxel size/bin width, in terms of intraclass correlation coefficient (> 0.75) and coefficient of variation (< 30%). The estimate of most textural radiomic features showed a linear significant (p < 0.05) correlation with resampling voxel size/bin width. Overall, radiomic features from T2 maps have proven to be less sensitive to image preprocessing than those from T1 maps, especially when varying bin width. Our results might corroborate the potential of radiomics from T1/T2 mapping in HCM and hopefully in other myocardial diseases. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of image preprocessing on radiomic features estimation from computed tomography (CT) imaging of locally advanced rectal cancer (LARC). CT images of 20 patients with LARC were used to estimate 105 radiomic features of 7 classes (shape, first-order, GLCM, GLDM, GLRLM, GLSZM, and NGTDM). Radiomic features were estimated for 6 different isotropic resampling voxel sizes, using 10 interpolation algorithms (at fixed bin width) and 6 different bin widths (at fixed interpolation algorithm). The intraclass correlation coefficient (ICC) and the coefficient of variation (CV) were calculated to assess the variability in radiomic features estimation due to preprocessing. A repeated measures correlation analysis was performed to assess any linear correlation between radiomic feature estimate and resampling voxel size or bin width. Reproducibility of radiomic feature estimate, when assessed through ICC analysis, was nominally excellent (ICC > 0.9) for shape features, good (0.75 < ICC ≤ 0.9) or moderate (0.5 < ICC ≤ 0.75) for first-order features, and moderate or poor (0 ≤ ICC ≤ 0.5) for textural features. A number of radiomic features characterized by good or excellent reproducibility in terms of ICC showed however median CV values greater than 15%. For most textural features, a significant (p < 0.05) correlation between their estimate and resampling voxel size or bin width was found. In CT imaging of patients with LARC, the estimate of textural features, as well as of first-order features to a lesser extent, is appreciably biased by preprocessing. Accordingly, this should be taken into account when planning clinical or research studies, as well as when comparing results from different studies and performing multicenter studies. [ABSTRACT FROM AUTHOR]

Radioembolization is a valuable therapeutic option in patients with unresectable intrahepatic cholangiocarcinoma. The essential implementation of the absorbed dose calculation methods should take into account also the specific tumor radiosensitivity, expressed by the α parameter. Purpose of this study was to retrospectively calculate it in a series of patients with unresectable intrahepatic cholangiocarcinoma submitted to radioembolization. Twenty-one therapeutic procedures in 15 patients were analysed. Tumor absorbed doses were calculated processing the post-therapeutic 90Y-PET/CT images and the pre-treatment contrast-enhanced CT scans. Tumor absorbed dose and pre- and post-treatment tumor volumes were used to calculate α and α3D parameters (dividing targeted liver in n voxels of the same volume with specific voxel absorbed dose). A tumor volume reduction was observed after treatment. The median of tumor average absorbed dose was 93 Gy (95% CI 81–119) and its correlation with the residual tumor mass was statistically significant. The median of α and α3D parameters was 0.005 Gy−1 (95% CI 0.004–0.008) and 0.007 Gy−1 (95% CI 0.005–0.015), respectively. Multivariate analysis showed tumor volume and tumor absorbed dose as significant predictors of the time to tumor progression. The knowledge of radiobiological parameters gives the possibility to decide the administered activity in order to improve the outcome of the treatment. [ABSTRACT FROM AUTHOR]

Given the inherent characteristics of nonlinearity and nonstationarity of iterative reconstruction algorithms in computed tomography (CT) imaging, this study aimed to perform, for the first time, a voxel-based characterization of noise properties in CT imaging with the ASiR-V and ASiR algorithms as compared with conventional filtered back projection (FBP). Multiple repeated scans of the Catphan-504 phantom were carried out. CT images were reconstructed using FBP and ASiR/ASiR-V with different blending levels of reconstruction (20%, 40%, 60%, 80%, 100%). Noise maps and their nonuniformity index (NUI) were obtained according to the approach proposed by the report of AAPM TG-233. For the homogeneous CTP486 module, ASiR-V/ASiR allowed a noise reduction of up to 63.7%/52.9% relative to FBP. While the noise reduction values of ASiR-V-/ASiR-reconstructed images ranged up to 33.8%/39.9% and 31.2%/35.5% for air and Teflon contrast objects, respectively, these values were approximately 60%/50% for other contrast objects (PMP, LDPE, polystyrene, acrylic, Delrin). Moreover, for all contrast objects but air and Teflon, ASiR-V showed a greater noise reduction potential than ASiR when the blending level was ≥40%. While noise maps of the homogenous CTP486 module showed only a slight spatial variation of noise (NUI < 5.2%) for all reconstruction algorithms, the NUI values of iterative-reconstructed images of the nonhomogeneous CTP404 module increased nonlinearly with blending level and were 19%/15% and 6.7% for pure ASiR-V/ASiR and FBP, respectively. Overall, these results confirm the potential of ASiR-V and ASiR in reducing noise as compared with conventional FBP, suggesting, however, that the use of pure ASiR-V or ASiR might be suboptimal for specific clinical applications. [ABSTRACT FROM AUTHOR]

Background: In the current clinical practice, radiometabolic therapy of Graves' disease is based on the administration of an amount of 131I-iodide defined according to two different modalities: administration of a fixed activity (up to a maximum of 555 MBq allowed by many national legislations on an outpatient basis) or an 131I-iodide activity individually defined so as to reach the certain fixed values of target thyroid-absorbed dose. The aim of this study was to prove the effectiveness of a personalized approach to cure Graves' disease based on the administration of a 131I activity defined according to the desired "optimal final thyroid mass." According to this model, one can predict the thyroid-absorbed dose following the administration of an activity as a function of the desired reduction of the baseline, pre-treatment mass of the gland. Methods: A total of 217 patients with Graves' disease were included in this study. They were randomly divided into five groups, of which four groups were divided based on fixed thyroid-absorbed dose value of 100 (Group A, n = 29), 200 (Group B, n = 25), 300 (Group C, n = 51), and 400 (Group D, n = 25), respectively, whereas patients of the final thyroid mass (mf) (Group V, n = 87) received a 131I activity calculated based on the desired "optimal" final thyroid mass according to the so-called "volume algorithm" approach. Results: At the 1-year follow-up, therapeutic success (i.e., a state of either hypothyroidism or euthyroidism) was achieved in 48% of patients in Group A (100 Gy), 64% in Group B (200 Gy), 78% in Group C (300 Gy), 96% in Group D (400 Gy), and 92% in Group V (mf). A significantly higher proportion of patients were was cured in Groups D and V (mf) than in Groups A, B, and C (P < 0.01). There was no statistical difference in cure rates between Groups D and V (mf). The median thyroid-absorbed dose was 407 Gy for Group D (400 Gy), significantly higher than 296 Gy for Group V (mf) (P < 0.001) and also significantly greater than the administered 131I activity (494 vs. 345 MBq, P < 0.001). Conclusions: This study indicates that the most effective thyroid-absorbed dose to be delivered for the radiometabolic therapy of patients with Graves' disease should not be based on a fixed dose but rather should be personalized. The new method based on thyroid mass reduction allows the optimization of 131I-iodide therapy for Graves' disease on an individual basis, achieving a high therapeutic efficacy while at the same time avoiding the administration of unjustified greater activities of 131I. [ABSTRACT FROM AUTHOR]

Purpose: To retrospectively compare early response to yttrium-90 radioembolization (Y90) according to volumetric iodine uptake (VIU) changes, Response Evaluation Criteria In Solid Tumor 1.1 (RECIST 1.1) and modified RECIST (mRECIST) in patients with intermediate-advanced hepatocellular carcinoma (HCC) and to explore their association with survival.Materials and Methods: Twenty-four patients treated with Y90 and evaluated with dual-energy computed tomography before and 6 weeks after treatment were included. VIU was measured on late arterial phase spectral images; 6-week VIU response was defined as: complete response (CR, absence of enhancing tumor), partial response (PR, ≥ 15% VIU reduction), progressive disease (PD, ≥ 10% VIU increase) and stable disease (criteria of CR/PR/PD not met). RECIST 1.1 and mRECIST were evaluated at 6 weeks and 6 months. Responders included CR and PR. Overall survival (OS) was evaluated by Kaplan-Meier analysis and compared by Cox regression analysis.Results: High intraobserver and interobserver agreements were observed in VIU measurements (k > 0.98). VIU identified a higher number of responders (18 patients, 75%), compared to RECIST 1.1 (12.5% at 6 weeks and 23.8% at 6 months) and mRECIST (29.2% at 6 weeks and 61.9% at 6 months). There was no significant correlation between OS and RECIST 1.1 (P = 0.45 at 6 weeks; P = 0.21 at 6 months) or mRECIST (P = 0.38 at 6 weeks; P = 0.79 at 6 months); median OS was significantly higher in VIU responders (17.2 months) compared to non-responders (7.4 months) (P = 0.0022; HR 8.85; 95% CI 1.29-88.1).Conclusion: VIU is highly reproducible; as opposite to mRECIST and RECIST 1.1, early VIU response correlates with OS after Y90 in intermediate-advanced HCC patients. [ABSTRACT FROM AUTHOR]

Breast imaging represents a relatively recent and promising field of application of quantitative diffusion-MRI techniques. In view of the importance of guaranteeing and assessing its reliability in clinical as well as research settings, the aim of this study was to specifically characterize how the main MR scanner system-related factors affect quantitative measurements in diffusion-MRI of the breast. In particular, phantom acquisitions were performed on three 1.5 T MR scanner systems by different manufacturers, all equipped with a dedicated multi-channel breast coil as well as acquisition sequences for diffusion-MRI of the breast. We assessed the accuracy, inter-scan and inter-scanner reproducibility of the mean apparent diffusion coefficient measured along the main orthogonal directions () as well as of diffusion-tensor imaging (DTI)-derived mean diffusivity (MD) measurements. Additionally, we estimated spatial non-uniformity of (NU) and MD (NUMD) maps. We showed that the signal-to-noise ratio as well as overall calibration of high strength diffusion gradients system in typical acquisition sequences for diffusion-MRI of the breast varied across MR scanner systems, introducing systematic bias in the measurements of diffusion indices. While and MD values were not appreciably different from each other, they substantially varied across MR scanner systems. The mean of the accuracies of measured and MD was in the range [−2.3%,11.9%], and the mean of the coefficients of variation for and MD measurements across MR scanner systems was 6.8%. The coefficient of variation for repeated measurements of both and MD was < 1%, while NU and NUMD values were <4%. Our results highlight that MR scanner system-related factors can substantially affect quantitative diffusion-MRI of the breast. Therefore, a specific quality control program for assessing and monitoring the performance of MR scanner systems for diffusion-MRI of the breast is highly recommended at every site, especially in multicenter and longitudinal studies. [ABSTRACT FROM AUTHOR]

Background: In the context of the coronavirus disease 2019 (COVID-19) pandemic, liver-directed therapies (LDTs) may offer minimally invasive integrative tools for tumor control. Among them, selective internal radiation therapy (SIRT) represents a safe, flexible and effective treatment. Purpose of this study is to present our experience with SIRT during the first wave of COVID-19 pandemic and provide an overview of the indications and challenges of SIRT in this scenario. Methods: We retrospectively analyzed the number of patients evaluated by Multidisciplinary Liver Tumor Board (MLTB) and who were undergoing LDTs between March and July 2020 and compared it with 2019. For patients treated with SIRT, clinical data, treatment details and the best radiological response were collected. Results: Compared to 2019, we observed a 27.5% reduction in the number of patients referred to MLTB and a 28.3% decrease in percutaneous ablations; transarterial chemoembolizations were stable, while SIRT increased by 64%. The majority of SIRT patients (75%) had primary tumors, mostly HCC. The best objective response and disease control rates were 56.7% and 72.2%, respectively. Conclusion: The first wave of the COVID-19 pandemic was characterized by an increased demand for SIRT, which represents a safe, flexible and effective treatment, whose manageability will further improve by simplifying the treatment workflow, developing user-friendly and reliable tools for personalized dosimetry and improving interdisciplinary communication. [ABSTRACT FROM AUTHOR]

CT scan images with metal artefacts may reduce the image quality and diagnosis of CT scan images. Metal Artefact Reduction (MAR) can effectively reduce artifacts caused by metal implants. ASIR-V plays a role in reducing noise and improving image quality. To prove the reduction of metal image artefacts and optimization of CT scan image quality after the application of MAR and ASIR-V (30,60,90) of Head and Neck CT Scan by finding the value of SNR, CNR, anatomical information and the level of metal artefact interference after metal artefact reduction. Quasi-type experimental research design with pre-post test only without control group design. The study sample was 15 CT scan images of head and neck with purposive sampling. SNR and CNR measurements were quantitatively analyzed using the Wilk test, followed by the Wilcoxon test. Anatomical information assessment was performed qualitatively by two radiologists and analyzed by kappa test. Anatomical information and the level of metal artefact interference with CT scan images were carried out by the Friedman test, followed by the Wilcoxon test. There is a difference in SNR Pvalue (p=0.000<0.05), CNR Pvalue (p=0.000>0.05), anatomical information Pvalue (p=0.000<0.05), level of metal artefacts Pvalue (p=0.000<0.05) after using MAR and ASIR V. The use of MAR and ASIR-V methods can reduce metal artefacts in images that contain artefacts with the use of MAR + ASIR-V 90% the most optimal. [ABSTRACT FROM AUTHOR]

The editorial presents that the European Journal of Nuclear Medicine and Molecular Imaging has made progress in 2006. The author presents that nuclear medicine leads the field of molecular imaging which is necessary for the proper diagnosis. The author points out the complexitiesinvolved in the process to ensure that only the best articles reach publication. The article also presents a list of people being acknowledged for their assistance in the review process.