There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The analysis of medical images has been woven into the fabric of the pattern analysis and machine intelligence (PAMI) community since the earliest days of these Transactions. Initially, the efforts in this area were seen as applying pattern analysis and computer vision techniques to another interesting dataset. However, over the last two to three decades, the unique nature of the problems presented within this area of study have led to the development of a new discipline in its own right. Examples of these include: the types of image information that are acquired, the fully three-dimensional image data, the nonrigid nature of object motion and deformation, and the statistical variation of both the underlying normal and abnormal ground truth. In this paper, we look at progress in the field over the last 20 years and suggest some of the challenges that remain for the years to come.

https://hal.inria.fr/inria-00615100/document

Medical image analysis: progress over two decades and the challenges ahead

The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm

https://www.lfb.lv/files/ESVS-AAA-guidelines.pdf

Management of abdominal aortic aneurysms clinical practice guidelines of the European society for vascular surgery.

Magnetic resonance elastography: Non-invasive mapping of tissue elasticity

MR elastography (MRE) images the intrinsic mechanical properties of soft tissues; e.g., the shear modulus, μ. The μ of the plantar soft tissues is important in understanding the mechanisms whereby the forces induced during normal motion produce ulcers that lead to amputation in diabetic feet. We compared the compliance of the heel fat pad to compressive forces and to shearing forces. The design of prosthetics to protect the foot depends on the proper understanding of the mechanisms inducing damage. 
	In the heel fat pads of six normal subjects, between 25 and 65 years of age, the μ for deformation perpendicular to the direction of weight bearing is similar but not identical to that determined for deformation along the weight bearing axis. The average difference between μ along the weight bearing axis and μ perpendicular to the weight bearing axis, is well correlated with age (Correlation Coefficient = 0.789). The p-value for the data being random was 0.0347 indicating that the observed difference is not likely to be random. The p-value for control points is 0.8989, indicating a random process. 
	The results are suggestive that the high compressive forces imposed during walking damage the heel fat pads over time resulting in softening to compression preferentially over shearing. It is important to validate the observed effect with larger numbers of subjects, and better controls including measures of activity, and to understand if diseases like diabetes increase the observed damage.

MR elastographic methods for the evaluation of plantar fat pads: Preliminary comparison of the shear modulus for shearing deformation and compressive deformation in normal subjects

The viscosity index of multigrade lubricants

An abdominal aortic aneurysm (AAA) is an abnormal, localized enlargement of the aorta. If untreated, a AAA will continue to enlarge in size and eventually rupture. Currently, AAA diameter is used as the principal indicator of impending rupture. However, this method it is not totally reliable. In an effort to improve the estimation of rupture risk, some researchers are currently studying the mechanical wall stresses of AAAs using patient-specific medical imaging techniques and finite element modeling [1,2]. The accuracy of these models depends significantly on the constitutive law used to describe the mechanical properties of the AAA tissue. To date, only isotropic constitutive laws have been used in these models.Copyright © 2002 by ASME

Mechanical Properties Characterization of Abdominal Aortic Aneurysm Tissue Using Biaxial Testing

Gouge features on metal-on-metal hip bearings can result from high stresses during rim contact

Most of the tibial bearings for knee prostheses are made from ultra-high molecular weight polyethylene (UHMWPE). The longevity of those bearings is less than ten years in many cases, owing to tribological failure. In total knee replacements, the polymer bearings are subjected to oscillatory rolling/sliding contact; sliding wear and contact fatigue can both be important modes of knee bearing failure under these conditions. This research applied accelerated testing techniques to assess the tribological behavior of several different UHMWPE tibial bearing materials. Accelerated aging of bearing material was done to simulate, within a few weeks, the long-term changes that previously have been documented in joint prosthesis bearings in use for 5 to 10 years or more. Cyclic wear and contact fatigue tests were carried out using two tribotesters, a knee simulator and a rolling/sliding contact tester, in order to determine the performance of unaged and aged bearing material. The relative merits of both types of model experiments were examined in this test program. Gravimetric and volumetric methods for measuring wear accurately in the tests were also evaluated. A large, established archive of joint bearings explanted from patients was used to confirm that the surface failure mechanisms observed in the laboratory were similar to clinical wear mechanisms.

Francis E. Kennedy

Papers

MR elastographic methods for the evaluation of plantar fat pads: Preliminary comparison of the shear modulus for shearing deformation and compressive deformation in normal subjects

The viscosity index of multigrade lubricants

Mechanical Properties Characterization of Abdominal Aortic Aneurysm Tissue Using Biaxial Testing

Gouge features on metal-on-metal hip bearings can result from high stresses during rim contact

Tribotesting of tibial bearings of knee prostheses