Keywords: Data Processing, MR Value

Motivation: Quantifying clinical MRI utilization is essential to identifying opportunities to improve workflow and efficiency and contribute to better patient access and increased value.

Goal(s): We aim to demonstrate the benefits of analytics tools to measure utilization and guide protocol optimization.

Approach: An advanced analytics methodology was developed to identify workflow improvements and measure the impact of protocol interventions.

Results: We quantified the impact of three interventions: 1) MR enterography protocol modification, 2) focused protocols for hepatocellular carcinoma surveillance, and 3) improved communication strategies for oblique image prescription for rectal cancer staging. All interventions were shown to improve MRI workflow and reduce exam time.

Impact: It is currently challenging to quantify the utilization of clinical MRI exams. Through the use of analytics tools to characterize MR exam utilization, opportunities for improvement can be identified. Such tools are essential to improve the value of MRI.

Keywords: Segmentation, Segmentation

Motivation: MRI-based brain volumetry is a valuable  tool to assess human brain development and brain disorders. However, insuring repeatability and reproducibility is essential for a larger dissemination.

Goal(s): Our goal was to compare the repeatability/reproducibility in volume measurements by different popular software tools.

Approach: We performed T2w scans and repeated T1w scans for 82 subjects on two 3T scanners. We computed the volume within- and between-scanner variabilities.

Results: Improved masking helps reduce variability in Freesurfer’s volume measurements. Synthseg and vol2Brain give better volume repeatability/reproducibility compared to Freesurfer.

Impact: Our results provide quantification of the effects on repeatability/reproducibility from different software enabling clinicians and researchers to make an informed choice for data processing.
 

Keywords: Visualization, Neuroscience, QA/QC

Motivation: Reliable neuroimaging pipelines require the implementation of robust QA/QC protocols.

Goal(s): Demonstrating a comprehensive QA/QC checkpoint on ‘unprocessed’ data of a mid-size dataset with MRIQC.

Approach: We employ MRIQC in the visual assessment and training of automatic QC to identify data that must be excluded or flagged within the ‘Human Connectome PHantom’ (HCPh) project.

Results: We developed a QA/QC protocol for unprocessed data within the HCPh project with MRIQC, comprehensively describing predefined exclusion criteria. We then demonstrate the application of the protocol to the corresponding data and report the outcomes.

Impact: We demonstrate how to streamline QA in a neuroimaging workflow, establishing robust QA/QC protocols with MRIQC. This approach adds to the tooling available to improve neuroimaging analyses, ensuring more accurate and reproducible results.

Keywords: Data Processing, Data Processing, Diffusion MRI, harmonization, fixel-based analysis, multisite

Motivation: Although multi-site DWI with large sample size has high statistical power and is sensitive to the subtle microstructural tissue changes, different models or protocols-induced measurement biases affect the reliability and reproducibility of the study. Therefore, harmonization is necessary to improve this issue.

Goal(s): The goal of our study is to evaluate the effectiveness of ComBat harmonization in mitigating measurement biases in FBA measures.

Approach: Our study utilized a traveling-subject DWI dataset, while various FBA measures were calculated and subsequently harmonized using the ComBat method.

Results: Our findings demonstrated that ComBat harmonization could effectively mitigate site, model, and protocol-induced measurement biases in FBA measures.

Impact: A significant contribution of this study is the seamless integration of ComBat into the fixel-based framework, which may enhance the reliability and reproducibility of multi-site research, offering a valuable tool for investigating microstructural tissue changes in the large-scale, multi-site studies.

Keywords: Data Processing, Brain

Motivation: The quantitative MRI community uses various acquisition approaches to extract the same quantitative maps while continuously working to find the agreement between them.

Goal(s): Our goal was to examine the agreement between the outcomes of two acquisition approaches, variable flip angle and MP2RAGE.

Approach: We produced a postprocessing method that generated qMRI maps from both acquisition approaches and controlled the similarities between the maps.

Results: Our new approach produced strong correlations between qMRI maps acquired with different sequences, emphasizing the agreement and consistency between them.

Impact: Our approach provides high agreement between different qMRI acquisition strategies, that may allow harmonization between different scanners and MR protocols and enable the usage of multiple datasets for research purposes.

Keywords: Data Processing, Phantoms

Motivation: The motivation came to acknowledge the aid for sequence standardization and to assess other site-related differences.

Goal(s): We aim to consider the SNR differences to improve comparability between sites in structural analysis of brain data.

Approach: We describe preliminary MRI phantom data from a longitudinal, multi-site MS study, illustrating an approach to sequence standardization and assessing site-related differences.

Results: Scan-rescan data were collected on three 3T MRI systems, using study specific, previously optimized sequences. Signal-to-noise ratio (SNR) was measured on a 16 x 16 grid structure within the phantom. Imaging voxels within the grid where algorithmically identified and SNR assessed in each cube.

Impact: Large between-site differences in SNR and spatial variability were observed, while longitudinal data showed good consistency in mean SNR and spatial appearance. These differences underscore the need for correction to improve between-site comparability.

Keywords: Software Tools, Software Tools

Motivation: Available online reading tools were not readily extendable for our comparative and inter-rater radiological assessment of an ultra-fast MRI protocol for dementia diagnosis.

Goal(s): We sought to develop a review tool  to enable scalable, geographically-distributed review of imaging protocols for diagnostic use.

Approach: We designed a web-based review tool and evaluated it for our needs, whilst ensuring flexibility for use across MRI studies.

Results: We developed the Extendable Review Tool using popular technologies to ease configuration for future studies.  We tested the tool using a dementia-specific questionnaire to compare ultra-fast and standard of care MRI scans across a range of contrasts.

Impact: Our Extendable Review Tool is customisable for any MRI-based study where geographically-distributed clinical reading of a set of images is needed. As an extendable and flexible web-based tool it has potential to aid a broad range of studies.

Keywords: Phantoms, MR Value, Quality Assurance

Motivation: Combining data from multiple sites is necessary in order to reach large sample sizes. This can be challenging, especially with portable ultra-low field (ULF) systems where conditions can vary.

Goal(s): To characterise image quality across multiple sites using ULF-MRI for future data harmonization.

Approach: Acquisition of QA scans across sites with centralised analysis for cross-sectional and longitudinal assessment. SNR and T2w contrast were calculated

Results: SNR was consistent within site, but some variation between sites. Image contrast was consistent, but extra care should be taken with software updates.

Impact: Quality assurance is essential for portable ultra-low field MRI. Our results demonstrate that SNR and contrast are useful metrics for image quality characterisation. This paves the way for harmonization of in vivo data in global studies using ultra-low field MRI.

Keywords: Phantoms, New Devices, Precision & Accuracy, Field Camera, Virtual Phantom

Motivation: Quality assurance (QA) of quantities derived from MRI requires elaborate phantoms. Instead, we send modulated RF signals into the scanner representing any initial test object (previous “Virtual Phantom ViP”) avoiding physical phantom difficulties.

Goal(s): Proof-of-principle of a novel step for QA of derived quantities, by combining two previous methods: a Field Camera (FC) to govern ViP. 

Approach: QA compares outputs from the unmodified scanner against the initial object. Tests evaluated the prototype technically, plus a derived QA example: myocardial bloodflow by first-pass contrast-enhanced myocardial perfusion.

Results: Phase stability without phase-locking to scanner was marginal, while first demonstrating FC+ViP QA of a derived quantity.

Impact: Quality assurance of derived quantities can require elaborate physical phantoms. Instead, we demonstrate novel field camera governance of the unmodified scanner's virtual phantom acquisition, reconstruction and analysis. We call for vendor cooperation in a new standardised inexpensive quality control interface.

Keywords: Software Tools, Data Analysis, Data Processing, Software Tools, Heart

Motivation: There is no uniform standard for the value of myocardial strain of different software vendors.

Goal(s): The study utilizes cardiac magnetic resonance feature tracking technique to assess the differences in myocardial strain parameters among healthy individuals of different age groups while employing two distinct vendor software tools. 

Approach: The study utilizes cardiac magnetic resonance feature tracking technique to assess myocardial strain parameters while employing two distinct vendor software tools. 

Results: The findings indicate variations in strain parameters across healthy individuals of varing age groups based on measurements obtained from CVI42 and Medis. Significant disparities in certain parameters are observed between the two suppliers. 

Impact: The normal reference values of myocardial strain from different suppliers can not be unified, and large samples and multi-center studies are needed in the future.

Keywords: Data Acquisition, MR Value, Protocol development

Motivation: MR protocol development in a clinical setting is essential for running an optimal MRI service within Radiology. However, there is no clear path to implementation.

Goal(s): The purpose of this study was to understand the varied nature of MR protocol development within the clinical setting in the UK.

Approach: We conducted a survey on MR protocol development, and approached MR Physicists, Radiographers and Radiologists within the UK. 

Results: Results highlighted the current lack of resources, particularly scanner and staff time. Respondents also highlighted the importance of implementing processes, enabling communication and disseminating results.

Impact: Establishing good practice in MRI protocol development can lead to major improvements within the radiological workflow, including efficiency and image quality gains for higher quality diagnosis and increased patient throughput. 

Keywords: Visualization, Tumor

Motivation: Change mapping techniques used in satellite imaging could be used for visualizing changes in longitudinal MRI.

Goal(s): To generate change maps to highlight tumor margins in longitudinal MRI scans of patients with brain metastasis.

Approach: We used the NYUMets public dataset. We adapted the VALE method used in satellite imaging to generate change saliency maps for patients with small brain metastasis by performing spatial and intensity registration over longitudinal MRI data.

Results: The change mapping technique made small tumors visually obvious, enhanced visualization of change in tumors and edema over time, and showed tumor boundaries that were not visible on T₁-post contrast images.

Impact: This work demonstrates that image processing techniques used in satellite imaging could be effectively used for tracking changes in longitudinal MRI. The proposed approach can lead to better treatment planning and patient progress monitoring due to its sensitivity to changes.

Keywords: Data Processing, Reproductive, longitudinal analyses; quantitative biomarkers

Motivation: Estimating longitudinal changes in imaging biomarkers is challenging due to the multiple sources of variation during acquisition that can influence the analysis of MRI data. 

Goal(s): To provide a robust estimate of longitudinal changes based on the comparison of cross-sectional imaging biomarkers from different time points.

Approach: We introduce RIMLA, a Reproducibility-Informed Method for Longitudinal Assessment that quantifies longitudinal imaging biomarker changes while accounting for the robustness of the underlying image processing algorithm. 

Results: As a first application, we show that RIMLA allows to identify multiple sclerosis lesion subtypes characterized by statistically significant enlargement or shrinkage over time. 

Impact: The here introduced Reproducibility-Informed Method for Longitudinal Assessment (RIMLA) allows to robustly detect small longitudinal changes in quantitative biomarkers. This increase in sensitivity can lead to better informed clinical decisions, for example during treatment monitoring or disease progression follow-ups.   

Keywords: Phantoms, Neuro, Phantom, diffusion, fat imaging

Motivation: Our multi-site studies require quality assurance for diffusion and proton density fat fraction (PDFF) imaging across vendors.

Goal(s): To establish DWI and PDFF protocols and analysis tools to evaluate reproducibility and reliability.

Approach: DWI and PDFF protocols were conducted on two 3T MRI systems (Philips and GE) on a diffusion phantom and a PDFF phantom. The measured ADC and PDFF values were compared across the scanners and also compared with the phantom reference values. Correlation coefficient and root-mean-square error (RMSE) were reported.

Results: High reproducibility and high accuracy were achieved across the MRI vendors as indicated by the correlation coefficients and RMSE.

Impact: Our results showed that quality assurance can be well maintained between the two MRI scanners, both DWI and PDFF measured on the two scanners at our institute are reliable and accurate, this has important implications for our future multi-site studies.