Skeletal muscle fat quantification by dual-energy computed tomography in comparison with 3T MR imaging

I Molwitz,A-K Ozga,C Ozden,G Adam,D Koehler,J Yamamura,M Leiderer,R Fischer,E Tahir,R Mcdonough

doi:10.1007/s00330-021-07820-1

I Molwitz, A-K Ozga + Show 8 more

Open Access

https://doi.org/10.1007/s00330-021-07820-1

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Abstract

ObjectivesTo quantify the proportion of fat within the skeletal muscle as a measure of muscle quality using dual-energy CT (DECT) and to validate this methodology with MRI.MethodsTwenty-one patients with abdominal contrast-enhanced DECT scans (100 kV/Sn 150 kV) underwent abdominal 3-T MRI. The fat fraction (DECT-FF), determined by material decomposition, and HU values on virtual non-contrast-enhanced (VNC) DECT images were measured in 126 regions of interest (≥ 6 cm2) within the posterior paraspinal muscle. For validation, the MR-based fat fraction (MR-FF) was assessed by chemical shift relaxometry. Patients were categorized into groups of high or low skeletal muscle mean radiation attenuation (SMRA) and classified as either sarcopenic or non-sarcopenic, according to the skeletal muscle index (SMI) and cut-off values from non-contrast-enhanced single-energy CT. Spearman’s and intraclass correlation, Bland-Altman analysis, and mixed linear models were employed.ResultsThe correlation was excellent between DECT-FF and MR-FF (r = 0.91), DECT VNC HU and MR-FF (r = - 0.90), and DECT-FF and DECT VNC HU (r = − 0.98). Intraclass correlation between DECT-FF and MR-FF was good (r = 0.83 [95% CI 0.71–0.90]), with a mean difference of - 0.15% (SD 3.32 [95% CI 6.35 to − 6.66]). Categorization using the SMRA yielded an eightfold difference in DECT VNC HU values between both groups (5 HU [95% CI 23–11], 42 HU [95% CI 33–56], p = 0.05). No significant relationship between DECT-FF and SMI-based classifications was observed.ConclusionsFat quantification within the skeletal muscle using DECT is both feasible and reliable. DECT muscle analysis offers a new approach to determine muscle quality, which is important for the diagnosis and therapeutic monitoring of sarcopenia, as a comorbidity associated with poor clinical outcome.Key Points• Dual-energy CT (DECT) material decomposition and virtual non-contrast-enhanced DECT HU values assess muscle fat reliably.• Virtual non-contrast-enhanced dual-energy CT HU values allow to differentiate between high and low native skeletal muscle mean radiation attenuation in contrast-enhanced DECT scans.• Measuring muscle fat by dual-energy computed tomography is a new approach for the determination of muscle quality, an important parameter for the diagnostic confirmation of sarcopenia as a comorbidity associated with poor clinical outcome.

Highlights

Sarcopenia is associated with a lower life expectancy [1, 2] and poorer prognosis in cancer patients [3]
Measuring muscle fat by dual-energy computed tomography is a new approach for the determination of muscle quality, an important parameter for the diagnostic confirmation of sarcopenia as a comorbidity associated with poor clinical outcome
While muscle strength can be measured clinically e.g. by the handgrip test, muscle quantity can be assessed by bioelectrical impedance analysis (BIA), dual-energy absorptiometry (DXA), computed tomography (CT), or magnetic resonance imaging (MRI) [7]

Summary

Introduction

Sarcopenia is associated with a lower life expectancy [1, 2] and poorer prognosis in cancer patients [3]. It is associated with increased rates of complication in patients requiring surgery or following trauma [4] and leads to longer hospitalization stays [4, 5]. While muscle strength can be measured clinically e.g. by the handgrip test, muscle quantity can be assessed by bioelectrical impedance analysis (BIA), dual-energy absorptiometry (DXA), computed tomography (CT), or magnetic resonance imaging (MRI) [7]. Less routinely used in primary care, CT and MRI are considered to be the gold standard for the determination of muscle quantity [7, 11]

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