Clinical Relevance of Ultrasound-based Intramuscular Fat Infiltration Assessment in Hospitalized Older Adults (FATUS-OLD) (FATUS-OLD)

Clinical Relevance of Matrix-based Ultrasound Assessment of Intramuscular Fat Infiltration in Hospitalized Older Adults (FATUS-OLD)

Sarcopenia in older adults is associated not only with loss of muscle mass but also with deterioration of muscle quality, particularly intramuscular fat infiltration. While muscle mass is commonly assessed, muscle quality remains insufficiently explored in routine clinical practice.

The FATUS-OLD study aims to evaluate the clinical relevance of a novel ultrasound-based multiparametric approach to assess intramuscular fat infiltration and muscle volume in hospitalized older adults undergoing rehabilitation. The main hypothesis is that higher intramuscular fat infiltration at baseline is associated with poorer recovery of physical performance at 6 months, independently of muscle volume.

This non-invasive, rapid, and radiation-free imaging approach could improve sarcopenia phenotyping and help identify new prognostic biomarkers for clinical follow-up and future interventional trials.

Study Overview

• Status: Not yet recruiting
• Conditions: Sarcopenia; Physical Performance Decline in Older Adults; Muscle Fat Infiltration

Detailed Description

FATUS-OLD is a prospective, monocentric, open-label, non-randomized observational study conducted at Nantes University Hospital. The study includes older adults aged 75 years and older hospitalized in a rehabilitation day-hospital program for gait or balance disorders.

Participants undergo ultrasound assessments of skeletal muscle using a CE-marked ultrasound device capable of measuring muscle volume and intramuscular fat infiltration through matrix-based analysis. Measurements are performed at baseline and during follow-up.

The primary objective is to assess the prognostic value of baseline intramuscular fat infiltration on physical performance recovery at 6 months, evaluated using the Short Physical Performance Battery (SPPB). Secondary objectives include the relationship between muscle volume, muscle quality, muscle strength, appendicular lean mass measured by bioelectrical impedance analysis, and clinically significant events such as falls, loss of independence, rehospitalization, and mortality.

The study is exploratory and aims to validate innovative ultrasound-derived biomarkers of muscle quality in a real-life geriatric population.

• Study Type: Observational
• Enrollment (Estimated): 115

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

All participants undergo standardized clinical assessments and ultrasound-based muscle evaluations as part of routine rehabilitation follow-up.

Description

Inclusion Criteria:

• Age ≥ 75 years
• Hospitalized in rehabilitation day-hospital program
• Written informed consent

Exclusion Criteria:

• Moderate to severe neurocognitive disorders
• Inability to comply with study procedures

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Observational cohort; All participants undergo standardized clinical assessments and ultrasound-based muscle evaluations as part of routine rehabilitation follow-up.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Short Physical Performance Battery (SPPB) score	Difference between SPPB score at baseline and at 6 months, used to evaluate recovery of physical performance in relation to baseline intramuscular fat infiltration.	Baseline to 6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Association between muscle volume and appendicular lean mass	Correlation between ultrasound-derived muscle volume (with and without correction for intramuscular fat infiltration) and appendicular lean mass measured by bioelectrical impedance analysis.	Baseline
Association between muscle volume and muscle strength	Relationship between muscle volume and maximal muscle strength for corresponding muscle groups, with and without correction for intramuscular fat infiltration.	Baseline and 6 months
Occurrence of clinically significant events	Incidence of falls, loss of independence, rehospitalization, cognitive decline, institutionalization, and mortality.	Up to 6 months

Collaborators and Investigators

• Sponsor: Nantes University Hospital
• Collaborators: AGENCE NATIONALE DE RECHERCHE

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): November 2, 2027

Study Registration Dates

• First Submitted: February 9, 2026
• First Submitted That Met QC Criteria: February 9, 2026
• First Posted (Actual): February 17, 2026

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 9, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Sarcopenia; Older adults; Ultrasound imaging; Physical performance; Muscle quality; Geriatric rehabilitation; Intramuscular fat
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Neuromuscular Manifestations; Pathological Conditions, Anatomical; Muscular Atrophy; Atrophy; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Sarcopenia
• Other Study ID Numbers: RC25_0301; 2025-A02297-42 (Other Identifier: ANSM)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No