{"title":"Assessing the Impact of Imaging Parameters on MRI Measurement of Kidney T<sub>2</sub>.","authors":"Alexander J Daniel, Susan T Francis","doi":"10.1002/jmri.70127","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>T<sub>2</sub>-mapping has promise to evaluate kidney pathophysiology. Prior studies show a large variance in kidney T<sub>2</sub>, likely due to the differing acquisition sequences.</p><p><strong>Purpose: </strong>To compare four T<sub>2</sub>-mapping sequences to investigate kidney T<sub>2</sub>.</p><p><strong>Study type: </strong>Phantom and prospective in vivo assessments.</p><p><strong>Participants: </strong>ISMRM/NIST and QASPER phantoms; 8 healthy volunteers (4 female, 30 ± 8 years).</p><p><strong>Field strength/sequence: </strong>3 T, spin echo-echo planar imaging (SE-EPI), multi-echo-spin echo (ME-SE), Gradient and Spin Echo (GraSE) vendor-provided sequences, and custom T<sub>2</sub>-prepared EPI, Dual-echo B<sub>0</sub>-mapping and DREAM B<sub>1</sub>-mapping.</p><p><strong>Assessment: </strong>T<sub>2</sub>-mapping accuracy in the ISMRM/NIST phantom in the presence of B<sub>0</sub> frequency offset and B<sub>1</sub> <sup>+</sup> by scaling of flip angles, and in the QASPER phantom in the presence of diffusion by altering pump rate compared to being turned off. Participants underwent a single 45-min exam to collect four T<sub>2</sub>-mapping sequences, B<sub>0</sub> and B<sub>1</sub> maps. In vivo T<sub>2</sub> values compared across sequences and the influence of B<sub>0</sub> and B<sub>1</sub> <sup>+</sup> was evaluated.</p><p><strong>Statistical tests: </strong>Shapiro-Wilk, Wilcoxon signed-rank, Student's t-test, Coefficient of Variation, Pearson's correlation coefficient, linear mixed effect model. p < 0.05 considered statistically significant.</p><p><strong>Results: </strong>SE-EPI, ME-SE, GraSE, and T<sub>2</sub>-prepared EPI had a mean absolute scaled error of 0.52, 0.52, 0.36, and 0.27 over the kidney T<sub>2</sub> range of the ISMRM/NIST phantom. GraSE was most robust to perturbations in B<sub>0</sub>/B<sub>1</sub> <sup>+</sup>. In the QASPER phantom, SE-EPI was highly sensitive to diffusion leading to T<sub>2</sub> shortening (66%), while multi-echo sequences had lower diffusion sensitivity ordered by shortest echo spacing (ME-SE 81%, T<sub>2</sub>-prepared EPI 90%, GraSE 95% reduction in T<sub>2</sub>). In vivo, SE-EPI measured T<sub>2</sub> was significantly lower than multi-echo sequences, and SE-EPI and T<sub>2</sub>-preparation had a -0.52 ± 0.08 and -0.57 ± 0.06 ms/% dependence on B<sub>1</sub> <sup>+</sup>.</p><p><strong>Data conclusion: </strong>To reduce B<sub>0</sub>, B<sub>1</sub> <sup>+</sup>, and diffusion sensitivity for kidney T<sub>2</sub>-mapping, a multi-echo sequence spanning echo times up to the kidney T<sub>2</sub> (~140 ms at 3 T) is recommended. Collecting data with different echo spacings can isolate the diffusion-related T<sub>2</sub> component.</p><p><strong>Evidence level: </strong>2.</p><p><strong>Technical efficacy: </strong>Stage 1.</p>","PeriodicalId":16140,"journal":{"name":"Journal of Magnetic Resonance Imaging","volume":" ","pages":""},"PeriodicalIF":3.5000,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Magnetic Resonance Imaging","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1002/jmri.70127","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}
引用次数: 0
Abstract
Background: T2-mapping has promise to evaluate kidney pathophysiology. Prior studies show a large variance in kidney T2, likely due to the differing acquisition sequences.
Purpose: To compare four T2-mapping sequences to investigate kidney T2.
Study type: Phantom and prospective in vivo assessments.
Field strength/sequence: 3 T, spin echo-echo planar imaging (SE-EPI), multi-echo-spin echo (ME-SE), Gradient and Spin Echo (GraSE) vendor-provided sequences, and custom T2-prepared EPI, Dual-echo B0-mapping and DREAM B1-mapping.
Assessment: T2-mapping accuracy in the ISMRM/NIST phantom in the presence of B0 frequency offset and B1+ by scaling of flip angles, and in the QASPER phantom in the presence of diffusion by altering pump rate compared to being turned off. Participants underwent a single 45-min exam to collect four T2-mapping sequences, B0 and B1 maps. In vivo T2 values compared across sequences and the influence of B0 and B1+ was evaluated.
Statistical tests: Shapiro-Wilk, Wilcoxon signed-rank, Student's t-test, Coefficient of Variation, Pearson's correlation coefficient, linear mixed effect model. p < 0.05 considered statistically significant.
Results: SE-EPI, ME-SE, GraSE, and T2-prepared EPI had a mean absolute scaled error of 0.52, 0.52, 0.36, and 0.27 over the kidney T2 range of the ISMRM/NIST phantom. GraSE was most robust to perturbations in B0/B1+. In the QASPER phantom, SE-EPI was highly sensitive to diffusion leading to T2 shortening (66%), while multi-echo sequences had lower diffusion sensitivity ordered by shortest echo spacing (ME-SE 81%, T2-prepared EPI 90%, GraSE 95% reduction in T2). In vivo, SE-EPI measured T2 was significantly lower than multi-echo sequences, and SE-EPI and T2-preparation had a -0.52 ± 0.08 and -0.57 ± 0.06 ms/% dependence on B1+.
Data conclusion: To reduce B0, B1+, and diffusion sensitivity for kidney T2-mapping, a multi-echo sequence spanning echo times up to the kidney T2 (~140 ms at 3 T) is recommended. Collecting data with different echo spacings can isolate the diffusion-related T2 component.
期刊介绍：
The Journal of Magnetic Resonance Imaging (JMRI) is an international journal devoted to the timely publication of basic and clinical research, educational and review articles, and other information related to the diagnostic applications of magnetic resonance.
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