Ultrasound and MRI Measurement of Quadriceps Femoris Muscle in Critically Ill Children (Echo-QF-IRM)

Comparison of Quadriceps Femoris Measurements in Critically Ill Children, Using Bedside Ultrasound and Magnetic Resonance Imaging

A vast majority of children admitted to paediatric intensive care (PICU) present with faltering growth during their admission. Muscle mass loss is an early, intense and frequent phenomenon in this setting, which is associated with impaired outcomes. Recent international guidelines recommend monitoring both nutritional status and muscle mass throughout hospital stay. Recent studies have used quadriceps femoris (QF) measurements as a surrogate for lean mass assessment, and monitored them with bedside ultrasound (QF thickness and QF cross sectional area). However, ultrasound cross sectional area inter-operator reproducibility has not been validated so far, and none of these ultrasound measurements has been validated against their gold standard i.e. magnetic resonance imaging measurements. This validation process should be conducted to allow interpreting ultrasound muscle measurements, prior to the implementation of ultrasound measurments into clinical practice. We hypothesise that ultrasound measurements of QF thickness and cross sectional area are reliable compared to the magnetic resonance imaging gold standard, and that QF cross sectional area has a reliable inter-operator reproducibility.

In sedated critically ill children, quadriceps femoris thickness and cross sectional area will be measured with thigh bedside ultrasound, performed by two trained operators consecutively. These two measurements will also be made at the exact same location on a magnetic resonance imaging transverse view of the thigh, to allow comparing them to ultrasound measurements.

intraclass correlation coefficient between ultrasound measurements and magnetic resonance imaging measurements

The mean of 4 measurements of quadriceps femoris thickness and the mean of 3 measurements of quadriceps femoris cross sectional area, performed by ultrasound, will be compared with the measurements means performed by magnetic resonance imaging

All ultrasound measurements will be made the same day than the magnetic resonance imaging, in a 6 hour-range prior or after the magnetic resonance imaging.

Inclusion Criteria: critically ill children from 0 to 17 years old magnetic resonance imaging planned for any medical reason sedated child for any medical reason absence of parental/patient refusal to participate to the study Exclusion Criteria: congenital neuromuscular disease no possible access to the thigh (e.g. dressing, drains, gypsum) anatomical anomaly of the limb, that would compromise localizing thigh landmarks (patella, groin) inability to obtain limb rest and/or thigh muscle decontraction risk induced by mobilization of the patient for ultrasound or magnetic resonance imaging purpose absence of social insurance