Discovering Associations Between Acoustic Emission and Magnetic Resonance Imaging Biomarkers From 10 Osteoarthritic Knees.

Objective: Acoustic emission (AE) sensed from knee joints during weight-bearing movements greatly increases with joint deterioration, but the relationship between AE patterns and specific anatomical damage, as seen for example in magnetic resonance imaging (MRI), is unknown. This knowledge is essential to validate AE biomarkers for the evaluation of knee joints, and forms the objective of this exploratory work to associate knee AE and MRI.

Methods: A novel processing framework is proposed to enable direct correlation between static 3D MRI of knees and their dynamic 1D AE during sit-stand-sit movements.

Use of acoustic emission to identify novel candidate biomarkers for knee osteoarthritis (OA).

Our objective was to determine the efficacy and feasibility of a new approach for identifying candidate biomarkers for knee osteoarthritis (OA), based on selecting promising candidates from a range of high-frequency acoustic emission (AE) measurements generated during weight-bearing knee movement. Candidate AE biomarkers identified by this approach could then be validated in larger studies for use in future clinical trials and stratified medicine applications for this common health condition. A population cohort of participants with knee pain and a Kellgren-Lawrence (KL) score between 1-4 were recruited from local NHS primary and secondary care sites.

Acoustic emission and angular movement variations from early adulthood healthy knees to late adulthood osteoarthritic knees.

From sit-stand-sit movements performed by healthy and osteoarthritic knees in three different age bands, this paper presents the investigation of the relationship between joint angular movement measured using electro-goniometers and acoustic emission measured using piezoelectric sensors. By partitioning joint movement in each sit-stand-sit cycle into sub-movement phases based on ascending and descending as well as acceleration and deceleration, the statistical analysis reveals aged and osteoarthritic knees exhibiting increased asymmetry and more variable angular movement compared with young and age-matched healthy knees, particularly in the descending-deceleration phase. With further evidence of a clear difference in the number of acoustic emission events detected from different knee groups, the study suggests the descending-deceleration phase likely to be most informative for quantitative assessment of knee aging and condition.

Discovering differences in acoustic emission between healthy and osteoarthritic knees using a four-phase model of sit-stand-sit movements.

By performing repeated sit-stand-sit movements to create stress on knee joints, short transient bursts of high frequency acoustic emission (AE) released by the knee joints were acquired from two age matched groups consisting of healthy and osteoarthritic (OA) knees, and significant differences between these two groups were discovered from the signal analysis performed. The analysis is based on a four-phase model of sit-stand-sit movements and a two-feature descriptor of AE bursts. The four phases are derived from joint angle measurement during movement, and they consist of the ascending-acceleration and ascending-deceleration phases in the sit-to-stand movement, followed by the descending-acceleration and descending-deceleration phases in the stand-to-sit movement.

A computationally efficient method for automatic registration of orthogonal x-ray images with volumetric CT data.

The paper presents a computationally efficient 3D-2D image registration algorithm for automatic pre-treatment validation in radiotherapy. The novel aspects of the algorithm include (a) a hybrid cost function based on partial digitally reconstructed radiographs (DRRs) generated along projected anatomical contours and a level set term for similarity measurement; and (b) a fast search method based on parabola fitting and sensitivity-based search order. Using CT and orthogonal x-ray images from a skull and a pelvis phantom, the proposed algorithm is compared with the conventional ray-casting full DRR based registration method.