Reference Ranges, Diagnostic and Prognostic Utility of Native <scp>T1</scp> Mapping and Extracellular Volume for Cardiac Amyloidosis: A Meta‐Analysis

<jats:sec><jats:title>Background</jats:title><jats:p>Cardiac MRI is central to the evaluation of cardiac amyloidosis (CA). Native T<jats:sub>1</jats:sub> mapping and extracellular volume (ECV) are novel MR techniques with evolving utility in cardiovascular diseases, including CA.</jats:p></jats:sec><jats:sec><jats:title>Purpose</jats:title><jats:p>To perform a meta‐analysis of the diagnostic and prognostic data of native T<jats:sub>1</jats:sub> mapping and ECV techniques for assessing CA.</jats:p></jats:sec><jats:sec><jats:title>Study Type</jats:title><jats:p>Systematic review and meta‐analysis.</jats:p></jats:sec><jats:sec><jats:title>Population</jats:title><jats:p>In all, 3520 patients including 1539 with CA from 22 studies retrieved following systematic search of Pubmed, Cochrane, and Embase.</jats:p></jats:sec><jats:sec><jats:title>Field Strength/Sequence</jats:title><jats:p>1.5T or 3.0T/modified Look–Locker inversion recovery (MOLLI) or shortened MOLLI (shMOLLI) sequences.</jats:p></jats:sec><jats:sec><jats:title>Assessment</jats:title><jats:p>Meta‐analysis was performed for all CA and for light‐chain (AL) and transthyretin (ATTR) subtypes. Thresholds were calculated to classify native T<jats:sub>1</jats:sub> and ECV values as not suggestive, indeterminate, or suggestive of CA.</jats:p></jats:sec><jats:sec><jats:title>Statistical Analysis</jats:title><jats:p>Area under the receiver‐operating characteristic curves (AUCs) and hazards ratios (HRs) with 95% confidence intervals (95% CI) were pooled using random‐effects models and Open‐Meta(Analyst) software.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Six studies were diagnostic, 16 studies reported T<jats:sub>1</jats:sub> and ECV values to determine reference range, and six were prognostic. Pooled AUCs (95% CI) for diagnosing CA were 0.92 (0.89–0.96) for native T<jats:sub>1</jats:sub> mapping and 0.96 (0.93–1.00) for ECV, with similarly high detection rates for AL‐ and ATTR‐CA. Based on the pooled values of native T<jats:sub>1</jats:sub> and ECV in CA and control subjects, the thresholds that suggested the absence, indeterminate, or presence of CA were identified as <994 msec, 994–1073 msec, and >1073 msec, respectively, for native T<jats:sub>1</jats:sub> at 1.5T. Pooled HRs (95% CI) for predicting all‐cause mortality were 1.15 (1.08–1.22) for native T<jats:sub>1</jats:sub> mapping as a continuous parameter, 1.19 (1.01–1.40) for ECV as a continuous parameter, and 4.93 (2.64–9.20) for ECV as a binary threshold.</jats:p></jats:sec><jats:sec><jats:title>Data Conclusion</jats:title><jats:p>Native T<jats:sub>1</jats:sub> mapping and ECV had high diagnostic performance and predicted all‐cause mortality in CA.</jats:p></jats:sec><jats:sec><jats:title>Level of Evidence</jats:title><jats:p>1</jats:p></jats:sec><jats:sec><jats:title>Technical Efficacy Stage</jats:title><jats:p>2</jats:p></jats:sec>