Evaluating Outcome Prediction via Baseline, End-of-Treatment, and Delta Radiomics on PET-CT Images of Primary Mediastinal Large B-Cell Lymphoma.

OBJECTIVES: Accurate outcome prediction is important for making informed clinical decisions in cancer treatment. In this study, we assessed the feasibility of using changes in radiomic features over time (Delta radiomics: absolute and relative) following chemotherapy, to predict relapse/progression and time to progression (TTP) of primary mediastinal large B-cell lymphoma (PMBCL) patients. MATERIAL AND METHODS: Given the lack of standard staging PET scans until 2011, only 31 out of 103 PMBCL patients in our retrospective study had both pre-treatment and end-of-treatment (EoT) scans. Consequently, our radiomics analysis focused on these 31 patients who underwent [18F]FDG PET-CT scans before and after R-CHOP chemotherapy. Expert manual lesion segmentation was conducted on their scans for delta radiomics analysis, along with an additional 19 EoT scans, totaling 50 segmented scans for single time point analysis. Radiomics features (on PET and CT), along with maximum and mean standardized uptake values (SUVmax and SUVmean), total metabolic tumor volume (TMTV), tumor dissemination (Dmax), total lesion glycolysis (TLG), and the area under the curve of cumulative standardized uptake value-volume histogram (AUC-CSH) were calculated. We additionally applied longitudinal analysis using radial mean intensity (RIM) changes. For prediction of relapse/progression, we utilized the individual coefficient approximation for risk estimation (ICARE) and machine learning (ML) techniques (K-Nearest Neighbor (KNN), Linear Discriminant Analysis (LDA), and Random Forest (RF)) including sequential feature selection (SFS) following correlation analysis for feature selection. For TTP, ICARE and CoxNet approaches were utilized. In all models, we used nested cross-validation (CV) (with 10 outer folds and 5 repetitions, along with 5 inner folds and 20 repetitions) after balancing the dataset using Synthetic Minority Oversampling TEchnique (SMOTE). RESULTS: To predict relapse/progression using Delta radiomics between the baseline (staging) and EoT scans, the best performances in terms of accuracy and F1 score (F1 score is the harmonic mean of precision and recall, where precision is the ratio of true positives to the sum of true positives and false positives, and recall is the ratio of true positives to the sum of true positives and false negatives) were achieved with ICARE (accuracy = 0.81 ± 0.15, F1 = 0.77 ± 0.18), RF (accuracy = 0.89 ± 0.04, F1 = 0.87 ± 0.04), and LDA (accuracy = 0.89 ± 0.03, F1 = 0.89 ± 0.03), that are higher compared to the predictive power achieved by using only EoT radiomics features. For the second category of our analysis, TTP prediction, the best performer was CoxNet (LASSO feature selection) with c-index = 0.67 ± 0.06 when using baseline + Delta features (inclusion of both baseline and Delta features). The TTP results via Delta radiomics were comparable to the use of radiomics features extracted from EoT scans for TTP analysis (c-index = 0.68 ± 0.09) using CoxNet (with SFS). The performance of Deauville Score (DS) for TTP was c-index = 0.66 ± 0.09 for n = 50 and 0.67 ± 03 for n = 31 cases when using EoT scans with no significant differences compared to the radiomics signature from either EoT scans or baseline + Delta features (p-value> 0.05). CONCLUSION: This work demonstrates the potential of Delta radiomics and the importance of using EoT scans to predict progression and TTP from PMBCL [18F]FDG PET-CT scans.

Development of scalable lymphatic system in the 4D XCAT phantom: Application to quantitative evaluation of lymphoma PET segmentations.

BACKGROUND: Digital anthropomorphic phantoms, such as the 4D extended cardiac-torso (XCAT) phantom, are actively used to develop, optimize, and evaluate a variety of imaging applications, allowing for realistic patient modeling and knowledge of ground truth. The XCAT phantom defines the activity and attenuation for a simulated patient, which includes a complete set of organs, muscle, bone, and soft tissue, while also accounting for cardiac and respiratory motion. However, the XCAT phantom does not currently include the lymphatic system, critical for evaluating medical imaging tasks such as sentinel node detection, node density measurement, and radiation dosimetry. PURPOSE: In this study, we aimed to develop a scalable lymphatic system in the XCAT phantom, to facilitate improved research of the lymphatic system in medical imaging. Using this scalable lymphatic system, we modeled the lymph node conglomerate pathology that is characteristically observed in primary mediastinal B-cell lymphoma (PMBCL). As an extended application, we evaluated positron emission tomography (PET) image quantification of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of these simulated lymphomas, though the phantoms may be applied to other imaging modalities and study design paradigms (e.g., image quality, detection). METHODS: A template model for the lymphatic system was developed based on anatomical data from the Visible Human Project of the National Library of Medicine. The segmented nodes and vessels were fit with non-uniform rational basis spline surfaces, and multichannel large deformation diffeomorphic metric mapping was used to propagate the template to different XCAT anatomies. To model conglomerates observed in PMBCL, lymph nodes were enlarged, converged within the mediastinum, and tracer concentration was increased. We used the phantoms as inputs to a PET simulation tool, which generated images using ordered subsets expectation maximization reconstruction with 2-8 mm Gaussian filters. Fixed thresholding (FT) and gradient segmentation were used to determine MTV and TLG. Percent bias (%Bias) and coefficient of variation (COV) were computed as measures of accuracy and precision, respectively, for each MTV and TLG measurement. RESULTS: Using the methodology described above, we introduced a scalable lymphatic system in the XCAT phantom, which allows for the radioactivity and attenuation ground truth to be generated in 116 ± 2.5 s using a 2.3 GHz processor. Within the Rhinoceros interface, lymph node anatomy and function were modified to create a cohort of 10 phantoms with lymph node conglomerates. Using the lymphoma phantoms to evaluate PET quantification of MTV, mean %Bias values were -9.3%, -41.3%, and 20.9%, while COV values were 4.08%, 7.6%, and 3.4% using 25% FT, 40% FT, and gradient segmentations, respectively. Comparatively for TLG, mean %Bias values were -27.4%, -45.8%, and -16.0%, while COV values were 1.9%, 5.7%, and 1.4%, for the 25% FT, 40% FT, and gradient segmentations, respectively. CONCLUSIONS: In this work, we upgraded the XCAT phantom to include a lymphatic system, comprised of a network of 276 scalable lymph nodes and corresponding vessels. As an application, we created a cohort of phantoms with lymph node conglomerates to evaluate lymphoma quantification in PET imaging, which highlights an important application of this work.

Metastatic Adamantinoma of the Femur on FDG PET/CT: Atypical Presentation of a Rare Disease.

ABSTRACT: Adamantinomas are rare malignant primary bone tumors, which typically arise in young patients, are generally low-grade tumors, and classically arise from the anterior tibial diaphysis. We present the case of a 70-year-old woman who underwent repeat imaging with FDG PET for a pathologically proven case of femoral adamantinoma who experienced a relatively rapid development of metastatic disease with an atypical distribution of lesions.

Dissolved Mn(III) in water treatment works: Prevalence and significance.

Dissolved Mn(III) has been identified at all stages throughout a Water Treatment Works (WTW) receiving inflow from a peaty upland catchment in NE England. Ninety percent of the influent total manganese into the WTW is particulate Mn, in the form of Mn oxide (>0.2 µm). Approximately 9% (mean value, n = 22, range of 0-100%) of the dissolved (<0.2 µm) influent Mn is present as dissolved Mn(III). Mn(III) concentrations are highest (mean of 49% of total dissolved Mn; n = 26, range of 17-89%) within the WTW where water comes into contact with the organic-rich sludges which are produced as waste products in the WTW. These Mn(III)-containing wastewaters are recirculated to the head of the works and constitute a large input of Mn(III) into the WTW. This is the first report of Mn(III) being identified in a WTW. The ability of Mn(III) to act as both an oxidant and a reductant is of interest to the water industry. Understanding the formation and removal of Mn(III) within may help reduce Mn oxide deposits in pipe networks. Further understanding how the ratio of Mn(III) to Mn(II) can be used to optimise dissolved Mn removal would save the water industry significant money in reducing discoloration 'events' at the customers' tap.

Predictive Accuracy of Chest Radiographs in Diagnosing Tachypneic Children.

OBJECTIVE: To test the predictive accuracy and reporting reproducibility of digital chest radiographs under low-resource conditions. METHODS: One hundred thirty four tachypneic children who presented to two Indian hospitals were enrolled. Based on review of 16 variables recorded in the Emergency Room (ER) by a senior pediatrician, children were given one of the four clinical diagnoses: pneumonia, wheezy disease, mixed and non-respiratory. Every child also had a digital CXR. It was interpreted by ER physician, pediatrician and two independent radiologists. All used the same standardized interpretation system (one or more of: normal, minor patches, major patches, hyperinflation, lobar change, pleural effusion). RESULTS: The 10 % of CXRs showing pleural effusions reliably predicted pneumonia and disease severity. For all other CXR findings, the correlation between CXR interpretation and clinical diagnosis was moderate to poor. Apart from pleural effusions, inter-observer agreements between interpretations made by ER physician, pediatrician and radiologist were also poor (kappa <0.4). CONCLUSIONS: With the exception of pleural effusions, CXR findings, interpreted by a radiologist, had moderate to poor power to predict respiratory diagnosis or disease severity defined by a pediatrician. Value of CXRs was further reduced by poor inter-observer agreement. When investigating tachypneic children under low-resource conditions, CXRs should be used with a clear understanding of their limitations.

Radiological prevalence of superior and posterior semicircular canal dehiscence in children.

OBJECTIVE: Establishing the prevalence of semicircular canal dehiscence in a pediatric population using temporal bone CT imaging. STUDY DESIGN: Retrospective analysis of all temporal bone CT scans during a 5-year period (2007-2012). METHODS: CT scan images were reformatted in the plane of the canals and assessed by two independent reviewers with a third to resolve disagreement. Detailed chart review was performed for those found to have dehiscence. Superior and posterior canals were classified as "dehiscent", "possibly dehiscent", "thin" or "normal" for each case. RESULTS: 649 temporal bones were assessed from 334 children (under 18 years of age). The prevalence rate of superior canal dehiscence (SCD) was 1.7% (3.3% of individuals). Posterior canal dehiscence (PCD) was present in 1.2% (2.1% of individuals). There were no cases of bilateral SCD, and one case of bilateral PCD. Age under 3 years was associated with a higher prevalence of thinning but not dehiscence. Congenital inner ear malformation was not related to a higher probability of dehiscence. The superior petrosal sinus was associated with the SCD in three cases (27.3%). Retrospective chart review highlighted possible vestibular symptoms in 3/11 patients with SCD (27.3%). CONCLUSIONS: This forms the largest pediatric study of canal dehiscence to date. This study's prevalence rate is significantly lower than previous reports. The identified association with overlying venous structures may reflect the etiological process involved. The occurrence in children supports the hypothesis of a congenital predisposition for development of canal dehiscence syndrome.