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Biomedical subjects

K K Wheatley

Publications and source records attributed to K K Wheatley.

6 recordsLinked to original sources
PubMed1986

Magnetic resonance imaging in childhood intracranial masses.

Magnetic Resonance Imaging (MRI) was compared with computerized tomography (CT) in 40 pediatric and adolescent patients with intracranial mass lesions as part of an ongoing project to determine the potential of MRI as a primary and definitive imaging modality. Multiplanar, multisequence MRI surpassed CT in providing mass localization, extent of involvement, and delineating the relationship to adjacent vital structures. Further development of MRI is encouraged to overcome current inconsistencies in pathologic characterization in order for this new technology to be employed not only as a primary screening modality but also as a definitive diagnostic test.

Adolescent↗
PubMed1984

Biomechanics of femur fractures secondary to gunshot wounds.

Nonlethal gunshot wounds to the femur produce four classical types of fractures. The 'drill-hole,' incomplete, and 'butterfly' fractures have been described in both clinical and experimental settings. The remote spiral fracture, sometimes attributed to the fall on the femur after wounding, is unique to the weight-loaded femur. A mathematical model relying on the beam in bending and the mechanics of a cylindrical shell is offered. An experimental method utilizing an apparatus (the 'osteoclast') designed to apply torsion, bending, or combined forces to cadaveric long bones is discussed. Femur failure proximal or distal to the impact site of a projectile is a function of stress risers operating at relatively great distances. Predictable primary and secondary peak moment locations for fracture are illustrated.

Adult↗
PubMed1984

Technical artifacts in magnetic resonance imaging.

Various artifacts of Magnetic Resonance Imaging (MRI) typically associated with currently available imaging techniques such as projection reconstruction and two-dimensional fourier transform (2D-FT) are described and illustrated. Examples of MRI artifacts were obtained with an imaging unit with a super conducting magnet operated at .15 Tesla and .27 Tesla with corresponding proton resonance frequency of 6.4 MHz and 11.25 MHz. The .15 Tesla images were obtained using projection reconstruction and the .27 Tesla using the 2D-FT method. Instrument related artifacts include those due to direct current (DC), projection, gradient offset, active shimming, phase encoding, and pulse sequencing. Other often encountered artifacts are related to the patient. These include those due to motion, ferromagnetic effect, and tissue contents. The cause of these artifacts and how (if possible) they may be eliminated or minimized is discussed.

Diagnostic Errors↗
PubMedDate not supplied

Development of the lateral eye of American horseshoe crabs: visual field and dioptric array.

We used a precision two-circle goniometer mounted to the stage of a compound microscope to determine the optical alignment and to measure the entrance aperture diameter of individual cuticular cones in the dioptric array of the lateral eye of juvenile horseshoe crabs in order to learn about the development of the visual field. Our results show that the extent of the visual field of juvenile horseshoe crabs with prosomal lengths about 20% of adult size (14-21 mm) is about 70% that of the visual field of adult horseshoe crabs (prosomal lengths: 100+ mm). The visual field of such juvenile animals covers between 77 and 85 deg vertically and 140 and 145 deg horizontally. Assuming that the dioptric array is uniform and square packed, the average interommatidial angle of the juvenile animals is between 5.6 and 6.0 deg as compared to 4.6 deg for an adult animal. The diameter of the entrance aperture of individual cuticular cones increases markedly with increasing animal size. In addition, we noted a statistically significant trend for entrance aperture diameters to increase from anterior to posterior within the eye for animals of all sizes. There may be a slight trend for entrance aperture diameters to increase from dorsal to ventral within the eye. Our results indicate that the extent of the visual field and the resolution of the lateral eye approach adult values in advance of animals' reaching sexual maturity.

Animals↗