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Portable Bedside Low-Field MRI for Assessment of Ventricular Size
Vinu Mathew1, Timothy R Lim1, Akhil Nair2
1From the Department of Medical Imaging (V.M., T.R.L., A.W.L., J.K., Y.A.C., A.B., S.M.), St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
Background And Purpose:
Low-field portable MRI (pMRI) has been shown to be a useful alternative neuroimaging tool in the emergency department (ED) and intensive care unit (ICU), potentially addressing challenges associated with the transport of critically ill patients. We aimed to evaluate the intermodality reliability between low-field pMRI and conventional neuroimaging (CN) for assessment of ventricular size and hydrocephalus.
Materials And Methods:
This retrospective study included all patients who underwent point-of-care 64 mT pMRI at a single tertiary hospital from March 30, 2022 to January 4, 2024, and had a follow-up CN, either CT or MRI, performed within 24 hours of the pMRI scan. Two raters independently evaluated pMRI for presence of hydrocephalus while blinded to CN. Bifrontal diameter, maximum skull, and Evans index were recorded. Interrater and intermodality agreement between pMRI and CN were evaluated by using the intraclass coefficient (ICC) and Cohen κ.
Results:
Fifty-six patients (mean age of 53.5 [±14.6] years, 61% men) were included in this study. Hydrocephalus was identified in 12 (21%) on pMRI and 13 (23%) on CN. Interrater agreement on pMRI was almost perfect for bifrontal diameter (ICC, 0.94; 95% CI, 0.89-0.97) and Evans index (ICC, 0.92; 95% CI, 0.86-0.95) and substantial for determination of hydrocephalus (κ = 0.72), all P < .01. Intermodality agreement between pMRI and CN was also near perfect for averaged measurements of bifrontal diameter (ICC, 0.94; 95% CI, 0.88-0.97), Evans index (ICC, 0.95; 95% CI, 0.92-0.97), and determination of hydrocephalus (κ = 0.95), all P < .01. Using CN as reference standard, pMRI had sensitivity and specificity of 92% (95% CI, 0.85-0.99) and 100% (95% CI, 1.0-1.0), respectively on qualitative visual assessment, and 80% (95% CI, 0.70-0.90) and 98% (95% CI, 0.94-1.0), respectively, on quantitative assessment by using an Evans index cutoff of 0.3.
Conclusions:
Low-field pMRI demonstrated excellent interrater agreement and strong concordance with CN in assessing ventricular size, highlighting its potential as an effective point-of-care tool for neurocritical care applications.
Insights
Low-field portable MRI (pMRI) shows high reliability for assessing ventricular size and hydrocephalus, agreeing well with conventional neuroimaging (CN). This makes pMRI a promising point-of-care tool for neurocritical care.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Low-field portable MRI (pMRI) offers a potential solution for neuroimaging in critical care settings, overcoming transport challenges.
- Conventional neuroimaging (CN) is the standard, but patient transport can be difficult.
Purpose of the Study:
- To evaluate the intermodality reliability between low-field pMRI and CN for assessing ventricular size and hydrocephalus.
- To determine the accuracy of pMRI in identifying hydrocephalus compared to standard methods.
Main Methods:
- Retrospective analysis of 56 patients undergoing point-of-care 64mT pMRI and subsequent CN within 24 hours.
- Two blinded raters independently assessed pMRI for hydrocephalus, measuring bifrontal diameter, maximum skull, and Evans index.
- Interrater and intermodality agreement were calculated using intraclass coefficient (ICC) and Cohen's kappa.
Main Results:
- pMRI demonstrated excellent interrater agreement for bifrontal diameter (ICC 0.94) and Evans index (ICC 0.92), and substantial agreement for hydrocephalus (κ = 0.72).
- Intermodality agreement between pMRI and CN was near perfect for bifrontal diameter (ICC 0.94), Evans index (ICC 0.95), and hydrocephalus determination (κ = 0.95).
- pMRI achieved high sensitivity (92%) and specificity (100%) for qualitative hydrocephalus assessment and good performance (80% sensitivity, 98% specificity) for quantitative assessment.
Conclusions:
- Low-field pMRI exhibits excellent interrater reliability and strong concordance with conventional neuroimaging for ventricular size and hydrocephalus assessment.
- pMRI is a viable and effective point-of-care tool for neurocritical care applications, enhancing diagnostic capabilities at the bedside.
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