The Image Biomarker Standardization Initiative validated consensus-based reference values for 169 radiomics features, thus enabling calibration and verification of radiomics software. Key results: • research teams found agreement for calculation of 169 radiomics features derived from a digital phantom and a human lung cancer on CT scan. • Of these 169 candidate radiomics features, good to excellent reproducibility was achieved for 167 radiomics features using MRI, 18F-FDG PET and CT images obtained in 51 patients with soft-tissue sarcoma.

The recent introduction of high-resolution molecular imaging technology is considered by many experts as a major breakthrough that will potentially lead to a revolutionary paradigm shift in health care and revolutionize clinical practice. This paper intends to balance the capabilities of the two major molecular imaging modalities used in nuclear medicine, namely positron emission tomography (PET) and single photon emission computed tomography (SPECT). The motivations are many-fold: (1) to gain a better understanding of the strengths and limitations of the two imaging modalities in the context of recent and ongoing developments in hardware and software design; (2) to emphasize that certain issues, historically and commonly thought as limitations of one technology, may now instead be viewed as challenges that can be addressed; (3) to point out that current state of the art PET and SPECT scanners can (greatly) benefit from improvements in innovative image reconstruction algorithms; and (4) to identify important areas of research in PET and SPECT imaging that will be instrumental to further improvements in the two modalities. Both technologies are poised to advance molecular imaging and have a direct impact on clinical and research practice to influence the future of molecular medicine.

Importance Midlife vascular risk factors have been associated with late-life dementia; whether these risk factors directly contribute to brain amyloid deposition is less well understood. Objective To determine if midlife vascular risk factors are associated with late-life brain amyloid deposition, measured using florbetapir positron emission tomography (PET). Design, Setting, and Participants Prospective cohort study in 3 U.S. communities (Washington County, MD; Forsyth County, NC; and Jackson, MS). 346 participants without dementia in the Atherosclerosis Risk in Communities (ARIC)-PET Amyloid Imaging Study; evaluation of vascular risk factors and markers since 1987-1989, with florbetapir PET scans (2011-2013). Exposures Vascular risk factors at ARIC baseline (ages 45-64) were evaluated in multivariable models including age, sex, race, APOE genotype, and educational level. Outcome Standardized Uptake Value Ratios (SUVR) were calculated from PET scans; a mean global cortical SUVR was calculated. Elevated florbetapir (defined at SUVR>1.2) was the dependent variable. Results In 322 participants without dementia and with nonmissing midlife vascular risk factors at baseline (43% black, 58% female, mean age 52), SUVR (positive in 164 (50.9%) of participants) was measured >20 years later (median followup 23.5; IQR 23.0-24.3) when participants were 67-88 (mean 76 y). Elevated body mass index midlife (BMI) was associated with elevated SUVR (OR 2.06, 95% CI 1.16, 3.65). At baseline, 65 participants had no vascular risk factors, 123 had one, and 134 had two or more; a higher number of midlife risk factors was associated with elevated amyloid SUVR at followup, 30.8% (n=20), 50.4% (n=62), and 61.2% (n=82), respectively. In adjusted models, compared to 0 midlife vascular risk factors, the odds ratio for elevated SUVR associated with 1 vascular risk factor was 1.88 (95% CI 0.95-3.72) and was 2.88 (95% CI 1.46-5.69) for 2 or more vascular risk factors No significant race by risk factor interactions were found. Late-life vascular risk factors were not associated with late-life brain amyloid: (2 or more late-life vascular risk factors compared to 0: OR 1.66, 95% CI 0.75-3.69). Conclusions and Relevance An increasing number of midlife vascular risk factors was significantly associated with elevated amyloid SUVR; this association was not significant for late-life risk factors. These findings are consistent with a role of vascular disease in the development of Alzheimer’s Disease.

In this paper, the authors review the field of resolution modeling in positron emission tomography (PET) image reconstruction, also referred to as point-spread-function modeling. The review includes theoretical analysis of the resolution modeling framework as well as an overview of various approaches in the literature. It also discusses potential advantages gained via this approach, as discussed with reference to various metrics and tasks, including lesion detection observer studies. Furthermore, attention is paid to issues arising from this approach including the pervasive problem of edge artifacts, as well as explanation and potential remedies for this phenomenon. Furthermore, the authors emphasize limitations encountered in the context of quantitative PET imaging, wherein increased intervoxel correlations due to resolution modeling can lead to significant loss of precision (reproducibility) for small regions of interest, which can be a considerable pitfall depending on the task of interest.