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Biomedical subjects

A S Hall

Publications and source records attributed to A S Hall.

At least 91 records · Page 5Linked to original sources
PubMed1976

Preliminary study of the in vivo motion in the canine shoulder.

An instrumented spatial linkage was used to measure the total motion in a canine shoulder as the dog was engaged in a variety of activities, including walking on a level carousel track, as well as over a hurdle, up and down a step, and up and down a ramp placed on the same track. For each activity, the motion data were analyzed, using 2 procedures. First, the linkage data and the joint contour data were combined by computer, and the motion was represented by a series of sequential computer drawings showing the scapular and humeral articular surfaces in their proper relative positions for selected increments of time during the various activities described. As an alternate but approximate method for describing the relative humeral-scapular motion, rotations about 3 mutually perpendicular axes through the average center of the shoulder joint were determined.

Animals↗
PubMedDate not supplied

MR-guided biopsy of the breast after lumpectomy and radiation therapy using two methods of immobilization in the lateral decubitus position.

We describe two methods of breast immobilization using the lateral decubitus position to increase patient comfort and access to the axillary tail for MR-guided biopsy in the postsurgical or irradiated breast. The first method uses a compression device with good immobilization but poor patient tolerance. The second approach uses a thermoplastic mesh material to form a rigid exoskeleton around the breast: immobilization is adequate and patient acceptability is good. The latter method is preferred and requires formal evaluation in larger scale trials.

Biopsy, Needle↗
PubMedDate not supplied

Observations on the choice of reconstruction matrix in magnetic resonance imaging.

This paper points out a number of ways in which the choice of imaging matrix can affect the performance of a machine in Magnetic resonance imaging. It observes that, contrary to most other techniques, there are advantages in some instances both in sensitivity and detectability through the use of lower resolution images which may not be obtainable in higher resolution ones--although it is equally true that there are other circumstances where the reverse is true. Considerations of effects arising from field inhomogeneity, patient motion, susceptibility mapping, and fluid flow are used to illustrate the argument.

Abdomen↗
PubMedDate not supplied

Use of closely coupled receiver coils in MR imaging: practical aspects.

The use of closely coupled receiver coils in magnetic resonance (MR) imaging of the brain and body is described. Design considerations are outlined, aspects of the choice of materials are discussed, and clinical applications are illustrated. Closely coupled receiver coils can provide a useful improvement in MR image quality.

Abscess↗
PubMedDate not supplied

Assessment of brain perfusion with MR imaging.

A technique for assessing brain perfusion with magnetic resonance (MR) imaging is described. This technique uses two spin echo sequences that are identical except that the second is sensitised to blood flow by use of a pair of unipolar gradients on either side of the 180 degree pulse. Differences in phase between the two sequences are displayed with a sensitivity to flow rates of +/- 0.5, +/- 1, and +/- 2 mm/s per full scale (+/- pi radians) deflection. The technique was validated for measurement of flow at these rates with a water phantom. Ten patients with cerebrovascular disease, multiple sclerosis, cerebral tumor, periventricular leukomalacia, and meningitis were studied. Differences between grey and white matter were normally seen in adults. Infants displayed differences between central and peripheral regions of the brain. Abnormalities were seen in all clinical cases. The technique will require further validation but it appears to provide a totally noninvasive method for assessing brain perfusion.

Adult↗