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Rapid determination of vertebral fat fraction over a large range of vertebral bodies
Author(s) -
Martin Jarad,
Nicholson Geoffrey,
Cowin Gary,
Ilente Clare,
Wong Winnie,
Kennedy Dominic
Publication year - 2014
Publication title -
journal of medical imaging and radiation oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.31
H-Index - 43
eISSN - 1754-9485
pISSN - 1754-9477
DOI - 10.1111/1754-9485.12143
Subject(s) - medicine , nuclear medicine , vertebra , sagittal plane , dual energy , bone mineral , anatomy , osteoporosis
Vertebral body fat fraction ( FF ) has been found to vary between lumbar vertebrae using magnetic resonance spectroscopy ( MRS ). We aim to more quickly assess a larger number of adjacent vertebrae using a single T 2‐weighted iterative decomposition of water and fat with echo asymmetry and least‐squares estimation ( IDEAL ) sequence. Methods Five men had dual‐energy X‐ray absorptometry ( DEXA ) and 1.5‐ T MR scans performed. MRS was performed at L 3, and a sagittal IDEAL sequence was also performed, resulting in separate fat‐only and water‐only readings from T 10 to S 2. For the IDEAL measurements, two independent observers followed a set reading protocol, with five observations each per vertebra. I ntra‐ and interobserver variability were assessed as deviations from the mean within and between observers, respectively. Results For FF measurements there was limited intra‐observer variation, with observers being on average within 3.4% of the pooled mean value. Similarly, there was good interobserver agreement, with an average variation of 2.1%. All men showed a reduction in FF of 1.6–7% between L 5 and S 1. Otherwise, there was a trend of increasing FF moving inferiorly from T 10 to S 2. This averaged 2.7% per vertebra (range 1.1–3.8%) and may not have been dependent on MRS ‐measured FF at the L 3 level. There was poor correlation between MRS ‐measured FF at L 2–4 and bone mineral density measured using DEXA ( R 2 = 0.06). Conclusion IDEAL measurements are generally reproducible between observers following a set protocol. There appears to be a gradient in FF moving from T 10 to S 2, with S 1 showing a consistent decrease. This variation may better describe overall marrow function than a single‐vertebra reading.