Computational Toolkit for Normalizing the Impact of CT Acquisition and Reconstruction on Quantitative Image Features - Quantitative image features (QIFs) such as radiomic and deep features hold enormous potential to improve the
detection, diagnosis, and treatment assessment of a wide range of diseases. Generated from clinically acquired
Computed Tomography (CT) scans, QIFs represent small pixel-wise changes that may be early indicators of
disease progression. However, detecting these changes is complicated by variations in how CT scans are
acquired and reconstructed. Ensuring repeatable and reproducible QIFs is necessary for developing predictive
models that achieve consistent performance across different clinical settings. This project's premise is that QIFs
are sensitive to CT parameters such as radiation dose level, slice thickness, reconstruction kernel, and
reconstruction method. The combined interactions among these parameters result in unique image conditions,
each yielding its own QIF value. Moreover, some clinical tasks and algorithms are more sensitive to differences
in QIF values than others. We hypothesize that a systematic, task-dependent framework to characterize the
impact of variability in CT parameters and effectively mitigate them will result in more consistent QIF values and
the performance of prediction models. Three interrelated innovations will be pursued in this work: 1) a novel
framework for characterizing the impact of different acquisition and reconstruction parameters on QIFs
and ML models using patient scans with known clinical outcomes in multiple domains; 2) a systematic
approach for selecting an optimal mitigation technique and evaluating the impact of normalization; and
3) an open-source software toolkit that formalizes the process of CT normalization, addressing real-
world use cases developed by academic and industry collaborators. In Aim 1, we will evaluate how multiple
CT parameters influence QIF values and model performance. Utilizing metrics of agreement and a heat map-
based visualization, we will determine under which image acquisition and reconstruction conditions the QIFs and
model performance are consistent. In Aim 2, we will assess and enhance normalization techniques for mitigating
the impact of differences in acquisition and reconstruction, targeting the set of imaging conditions that are most
relevant to a clinical task. In Aim 3, we will engage a spectrum of external stakeholders to guide the development
and adoption of a software toolkit called CT-NORM. Three distinct clinical domains will drive our efforts: lung
nodule detection (which relies on identifying small regions of high contrast differences to identify nodules),
interstitial lung disease quantification (which depends on characterizing texture differences), and ischemic core
assessment (which relies on detecting low contrast differences in brain tissue). CT-NORM will provide the
scientific community with an approach and a unified toolkit to characterize and mitigate the impact of
reconstruction and acquisition parameters on QIFs and prediction model performance. By addressing critical
sources of variability, we will improve the process of generating QIFs and facilitate the discovery of precise and
reproducible imaging phenotypes of disease.
