Voxel-wise body composition analysis using image registration of a three-slice CT imaging protocol: methodology and proof-of-concept studies.

BACKGROUND: Computed tomography (CT) is an imaging modality commonly used for studies of internal body structures and very useful for detailed studies of body composition. The aim of this study was to develop and evaluate a fully automatic image registration framework for inter-subject CT slice registration. The aim was also to use the results, in a set of proof-of-concept studies, for voxel-wise statistical body composition analysis (Imiomics) of correlations between imaging and non-imaging data. METHODS: The current study utilized three single-slice CT images of the liver, abdomen, and thigh from two large cohort studies, SCAPIS and IGT. The image registration method developed and evaluated used both CT images together with image-derived tissue and organ segmentation masks. To evaluate the performance of the registration method, a set of baseline 3-single-slice CT images (from 2780 subjects including 8285 slices) from the SCAPIS and IGT cohorts were registered. Vector magnitude and intensity magnitude error indicating inverse consistency were used for evaluation. Image registration results were further used for voxel-wise analysis of associations between the CT images (as represented by tissue volume from Hounsfield unit and Jacobian determinant) and various explicit measurements of various tissues, fat depots, and organs collected in both cohort studies. RESULTS: Our findings demonstrated that the key organs and anatomical structures were registered appropriately. The evaluation parameters of inverse consistency, such as vector magnitude and intensity magnitude error, were on average less than 3 mm and 50 Hounsfield units. The registration followed by Imiomics analysis enabled the examination of associations between various explicit measurements (liver, spleen, abdominal muscle, visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), thigh SAT, intermuscular adipose tissue (IMAT), and thigh muscle) and the voxel-wise image information. CONCLUSION: The developed and evaluated framework allows accurate image registrations of the collected three single-slice CT images and enables detailed voxel-wise studies of associations between body composition and associated diseases and risk factors.

Strategies to Improve the Clinical Outcomes for Direct-to-Consumer Pharmacogenomic Tests.

Direct-to-consumer genetic tests (DTC-GT) have become a bridge between marketing and traditional healthcare services. After earning FDA endorsement for such facilities, several fast-developing companies started to compete in the related area. Pharmacogenomic (PGx) tests have been introduced as potentially one of the main medical services of such companies. Most of the individuals will be interested in finding out about the phenotypic consequences of their genetic variants and molecular risk factors against diverse medicines they take or will take later. Direct-to-consumer pharmacogenomic tests (DTC-PT) is still in its young age, however it is expected to expand rapidly through the industry in the future. The result of PGx tests could be considered as the main road toward the implementation of personalized and precision medicine in the clinic. This narrative critical review study provides a descriptive overview on DTC-GT, then focuses on DTC-PT, and also introduces and suggests the potential approaches for improving the clinical related outcomes of such tests on healthcare systems.

Effects of neurohormonal antagonists on blood pressure in patients with heart failure with reduced ejection fraction (HFrEF): a systematic review protocol.

BACKGROUND: Several cardiovascular pathologies cause heart failure. Heart failure with reduced ejection fraction (HFrEF) is deteriorated by neurohormonal activation, so neurohormonal antagonists are recommended in HFrEF patients. They improve morbidity, mortality, and quality of life and reduce hospital admissions. Heart failure treatment guidelines recommend achieving target doses of those drugs. However, many clinicians prescribe suboptimal doses for the fear of inducing hypotension. The aim of this systematic review and meta-analysis is to understand whether it is still beneficial to uptitrate the doses of those drugs even if the patient is at the risk of developing hypotension. METHODS: The primary outcome is symptomatic or asymptomatic hypotension in patients on neurohormonal antagonist drugs for HFrEF. Secondary outcomes are blood pressure reduction, New Yok Heart Association functional class deterioration, non-fatal cardiovascular events, cardiovascular mortality, all-cause mortality, heart failure hospitalizations, and adverse events. Randomized controlled trials involving adults with HFrEF will be included. Comprehensive literature search will be done in MEDLINE, Scopus, Web of Science, WHO Global Index Medicus, and the Cochrane Central Register of Controlled Trials. MEDLINE will be searched first using controlled vocabulary and free text terms and then adapted to other databases. Linear and nonlinear dose-response meta-analyses will be conducted. Publication bias and statistical heterogeneity will be tested by Egger's regression and Cochran's Q tests, respectively. Sensitivity, subgroup, and meta-regression analyses will be performed. Grading of Recommendations Assessment, Development and Evaluation approach will be used to judge the quality of evidence. DISCUSSION: This systematic review and meta-analysis will provide information about the risk of hypotension in patients on neurohormonal antagonist drugs for HFrEF. The results will be published in a peer-reviewed journal. The implications for further research will be discussed. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019140307.