Dual-Energy CT muscle fat fraction as a new imaging biomarker of body composition and survival predictor in critically ill patients

Jennifer Erley; Kevin Roedl; Ann-Kathrin Ozga; Geraldine de Heer; Niklas Schubert; Julia Breckow; Christoph Burdelski; Enver Tahir; Stefan Kluge; Tobias B Huber; Jin Yamamura; Gerhard Adam; Isabel Molwitz

doi:10.1007/s00330-024-10779-4

Dual-Energy CT muscle fat fraction as a new imaging biomarker of body composition and survival predictor in critically ill patients

Eur Radiol. 2024 May 22. doi: 10.1007/s00330-024-10779-4. Online ahead of print.

Authors

Affiliations

¹ Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
² Department of Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
³ Institute of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
⁴ III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
⁵ Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
⁶ Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. i.molwitz@uke.de.

PMID: 38777903
DOI: 10.1007/s00330-024-10779-4

Abstract

Objective: To analyze changes in the muscular fat fraction (FF) during immobilization at the intensive care unit (ICU) using dual-energy CT (DECT) and evaluate the predictive value of the DECT FF as a new imaging biomarker for morbidity and survival.

Methods: Immobilized ICU patients (n = 81, 43.2% female, 60.3 ± 12.7 years) were included, who received two dual-source DECT scans (CT1, CT2) within a minimum interval of 10 days between 11/2019 and 09/2022. The DECT FF was quantified for the posterior paraspinal muscle by two radiologists using material decomposition. The skeletal muscle index (SMI), muscle radiodensity attenuation (MRA), subcutaneous-/ visceral adipose tissue area (SAT, VAT), and waist circumference (WC) were assessed. Reasons for ICU admission, clinical scoring systems, therapeutic regimes, and in-hospital mortality were noted. Linear mixed models, Cox regression, and intraclass correlation coefficients were employed.

Results: Between CT1 and CT2 (median 21 days), the DECT FF increased (from 20.9% ± 12.0 to 27.0% ± 12.0, p = 0.001). The SMI decreased (35.7 cm²/m² ± 8.8 to 31.1 cm²/m² ± 7.6, p < 0.001) as did the MRA (29 HU ± 10 to 26 HU ± 11, p = 0.009). WC, SAT, and VAT did not change. In-hospital mortality was 61.5%. In multivariable analyses, only the change in DECT FF was associated with in-hospital mortality (hazard ratio (HR) 9.20 [1.78-47.71], p = 0.008), renal replacement therapy (HR 48.67 [9.18-258.09], p < 0.001), and tracheotomy at ICU (HR 37.22 [5.66-245.02], p < 0.001). Inter-observer reproducibility of DECT FF measurements was excellent (CT1: 0.98 [0.97; 0.99], CT2: 0.99 [0.96-0.99]).

Conclusion: The DECT FF appears to be suitable for detecting increasing myosteatosis. It seems to have predictive value as a new imaging biomarker for ICU patients.

Clinical relevance statement: The dual-energy CT muscular fat fraction appears to be a robust imaging biomarker to detect and monitor myosteatosis. It has potential for prognosticating, risk stratifying, and thereby guiding therapeutic nutritional regimes and physiotherapy in critically ill patients.

Key points: The dual-energy CT muscular fat fraction detects increasing myosteatosis caused by immobilization. Change in dual-energy CT muscular fat fraction was a predictor of in-hospital morbidity and mortality. Dual-energy CT muscular fat fraction had a predictive value superior to established CT body composition parameters.

Keywords: Body composition; Computed tomography; Critical illness; Myosteatosis; Spectral-CT.