Ruud van Heeswijk

Keywords: Contrast mechanisms: Relaxometry, Image acquisition: Quantification, Transferable skills: Reproducible research

Parametric mapping (also known as qMRI, compositional MRI, T1/T2 mapping, etc.) has made critical diagnostic contributions in most subspecialties of radiology because it provides compositional information on the tissue, but it is not always clear what is needed in new technologies. After an introduction on common sources of bias and variance of the relaxation parameters, we will discuss how to validate new mapping techniques. This includes how to quantify metrics such as accuracy, precision, reproducibility, sensitivity, and specificity through numerical simulations, phantoms, animal models, healthy volunteers, and patient cohorts.

Kelly Jarvis

Keywords: Contrast mechanisms: Flow

Blood flow imaging is widely used for the assessment of cardiovascular health. Methods for 2D flow imaging have become routine in the clinical workflow while the use of 4D flow MRI is gaining prevalence worldwide. This educational talk will review the fundamentals of 2D flow imaging as well as 4D flow MRI. The focus will be on key aspects of integrating these techniques into the clinical workflow. Topics such as selection of acquisition parameters and considerations for data analysis will be covered. Future directions such as real-time 2D flow imaging will also be discussed.

Harrison Kim

Keywords: Contrast mechanisms: Perfusion

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) assesses tissue perfusion, which is crucial for diagnosing various diseases. Quantitative analysis improves accuracy but faces challenges due to inter/intra-scanner variability. Proposed solutions include using phantoms with known contrast-agent concentrations. The Point-of-care Portable Perfusion Phantom (P4) addresses this, reducing measurement variations across scanners. Challenges remain in peripheral device portability, but efforts are underway. Despite advancements, ensuring clinical advantage outweighs costs is crucial for effective implementation.

Mariam Andersson

Keywords: Contrast mechanisms: Diffusion, Contrast mechanisms: Microstructure

Diffusion MRI can provide clinically valuable information regarding the microstructural composition of tissue. There exist many signal representations and models that provide different interpretations of tissue structure of components. However, their validation is necessary to ensure their sensitivity and specificity to the underlying anatomy of interest. This lecture aims to outline the key points to consider when evaluating diffusion MRI techniques and outcome measures, and to present recent advancements in MRI validation techniques, including: novel tissue imaging modalities, Monte Carlo simulations on numerical phantoms, and physical phantoms.

Michael Middleton

Keywords: Body: Liver, Contrast mechanisms: Fat

This talk will summarize the Draft QIBA PDFF Conformance Statement for liver MRI-PDFF which focuses on chemical-shift-encoded PDFF biomarker validation on conventional MRI scanners for clinical care. We will also use that document as a starting point to discuss validation of new MRI-PDFF techniques on conventional scanners, as well as novel new techniques such as low cost, portable, point-of-care MR-based liver PDFF assessment based on diffusion. We will also briefly discuss other opportunities to qualify and validate PDFF biomarkers, including in the context of drug development clinical trials, and in particular with regard to the FDA Biomarker Qualification Program (BQP).

Hongjiang Wei

Keywords: Contrast mechanisms: Susceptibility

QSM and subvoxel QSM methods have facilitated the quantification of brain iron and myelin in neuroimaging research. These quantitative imaging techniques offer valuable insights into neurodegenerative diseases such as Parkinson's and the potential for studying tissue subvoxel susceptibilities outside of the brain. However, accurately quantifying susceptibility values and distinguishing between different sources of susceptibility pose significant challenges that necessitate robust modeling and analysis techniques. Validating susceptibility measurements against histological or other reference standards and establishing standardized protocols for data acquisition, processing, and validation are crucial steps to ensure the reliability and reproducibility of results across various studies.

Jae Mo Park

Keywords: Contrast mechanisms: Hyperpolarization, Contrast mechanisms: Molecular Imaging, Contrast mechanisms: Hyperpolarized MR (Non-Gas)

Applying hyperpolarized (HP) probes to in vivo investigation requires strategic planning and proper interpretation, based on comprehensive understanding of physiology, MR acquisition methods, and chemical properties. This lecture aims to provide general guidance on experimental design, including sample preparation, physiological modulation, hardware selection, MR acquisition, and data analysis, for applying HP probes to evaluate in vivo performance. This evaluation is based on the chemical properties of the probe and the physiological/metabolic targets to be measured.

Yen-Yu Ian Shih

Keywords: Contrast mechanisms: fMRI

fMRI contrast often reflects changes in CBV, CBF, and oxygen metabolism, influenced by complex neuronal inputs and microcircuitry activities. Validating these contrasts involves comparing ground truth to fMRI's indirect measurements, with the understanding that fMRI indicates activity events in brain areas with limited insights into the underlying neuronal processes. This lecture discusses literature that contributes to fMRI's specificity and reproducibility improvements and highlights two animal studies: one examines the impact of often-overlooked vasoactive neurochemicals on fMRI readings, and the other explores an fMRI contrast for measuring neuronal activity, along with nuances in its acquisition and analysis that could introduce artifacts.