The biomechanical interaction between the residual limb and the prosthetic socket determines the quality of fit of the socket in lower limb prosthetics. An understanding of this interaction and the development of quantitative measures to predict the quality of fit of the socket are important for optimal socket design. Finite-element modeling is used widely for biomechanical modeling of the limb/socket interaction and requires information on the internal and external geometry of the residual limb. Volumetric imaging methods such as X-ray computed tomography, magnetic resonance imaging, and ultrasound have been used to obtain residual limb shape information. Of these modalities, ultrasound has been introduced most recently and its development for visualization in prosthetics is the least mature. This paper reviews ultrasound image acquisition and processing methods as they have been applied in lower limb prosthetics.

Ultrasound imaging in lower limb prosthetics

Purpose
To introduce and validate an unsupervised muscle and fat quantification algorithm based on joint analysis of water-suppressed (WS), fat-suppressed (FS) and water-and-fat (non-suppressed) volumetric MR images of the mid-thigh region.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/jmri.22842

Automated quantification of muscle and fat in the thigh from water-, fat-, and nonsuppressed MR images

Segmentation of fat and muscle from MR images of the thigh by a possibilistic clustering algorithm.

Muscle characterisation by NMR imaging and spectroscopic techniques

Fat and water fractions were quantified at high field using a chemical shift-selective inversion recovery (CSS-IR) sequence to address the major difficulties encountered at high field by phase-sensitive techniques used for fat/water discrimination. Water- and fat-suppressed images were perfectly registered, which is a prerequisite for quantification. Immunity of the inversion pulse to B1 field modulations and off-resonance effects was tested for two adiabatic inversion pulses, with hyperbolic secant and asymmetric hyper-pulse waveforms. Taking into account adiabaticity, immunity to off-resonance, radiofrequency power requirements, and specific absorption rate, the former was chosen. A close correlation was found between fat content measured by CSS-IR at 4.7 T (R2= 0.97, P < 0.001) and 9.4 T (R2= 0.99, P < 0.05) and that measured by Soxhlet extraction. Different sources of bias (lowsignal-to-noise ratio, magnetization transfer effect) are discussed. J. Magn. Reson. Imaging 2000;12:488–496. © 2000 Wiley-Liss, Inc.

Imaging of water and fat fractions in high‐field MRI with multiple slice chemical shift‐selective inversion recovery

A fully automatic method for the segmentation of muscle, subcutaneous and inter-muscular fat from MR images of the thigh is presented. The process is rather robust, able to recognize men from women and thus to characterize patients affected by Gushing's disease.

Automatic muscle/fat quantification on MR images

The calculation of accurate T1 parametric image is performed by collecting a series of spin-echo images with different T1 weightings (variable repetition times) This relaxation time must be estimated by non-linear fitting for each pixel The aim of this work is to propose an efficient algorithm, based on Newton-Raphson principle, which reduces calculation time by three in comparison with the traditional Newton-Raphson one >

E. Erbland

Papers

Automatic muscle/fat quantification on MR images

An efficient Newton-Raphson algorithm for T1 parametric image estimation with MR spin-echo acquisitions