Biomedical subjects

Makiko Kouchi

Publications and source records attributed to Makiko Kouchi.

3 recordsLinked to original sources

PubMed2006

Analysis of skin movement with respect to flexional bone motion using MR images of a hand.

This study describes the methodology for analyzing skin movement with respect to the predefined flexional motion of the hand. The 3D in vivo geometric data were acquired through magnetic resonance (MR) scanning of multiple hands in various postures. Custom software was developed to segment MR images and to generate polygonal isosurfaces. A new bone coordinate system (BCS) was defined to describe the skin movement measured with the skin-surface markers. The BCS was defined by the surface registration technique, which could minimize the distance among the 3D polygonal surfaces of different postures. MR images of six subjects in the 3 postures were captured with skin-surface markers for the experiment. Skin movement on the second metacarpal bone, which was fixed during the flexional motion, ranged from 1.169 to 10.885 mm. While the distance of the skin movement varied from one subject to another, a common skin movement direction was observed among the six subjects. For the repeatability evaluation of the proposed method, the MR images of the same subject were independently processed 10 times by a trained operator. The standard deviation of the skin movement on the second metacarpal of the index finger with respect to the predefined flexional motion ranged from 0.45 to 0.74 mm.

Bone and Bones↗

PubMed2004

Analysis of 3D face forms for proper sizing and CAD of spectacle frames.

Three-dimensional morphological variations in the human face were analysed using digital models of the human face, and the usefulness of such analysis in designing industrial products was demonstrated by validating spectacle frame designs based on an original sizing system developed based on the analysis. A normalized model of the three-dimensional face form was made for each of 56 young adult Japanese males. The morphological distances between subjects were defined, and subjects were divided into four groups based on analysis of the distance matrix. A prototype spectacle frame was designed for the average form of each of the four groups. Tightening force of the prototype frames was adjusted using the materialized average forms with soft material placed at the nasal bridge and side of the head. Four prototype frames as well as a conventional frame were evaluated using sensory evaluation and physical measurement of the pressure and slip in 38 young adult male subjects. For each of the 38 subjects, prototype frames were ranked according to the morphological similarity of the subjects and the average form of the four groups: the frame designed for the average form of the group most similar to the subject was #1, the frame designed for the average form of the next most similar group was #2, and so on. For the groups with smaller or narrower faces, new frame #1 was most preferred and had the best overall fit, smallest slip sensation and largest pressure sensation. The groups with larger or wider faces preferred tighter frames than new frame #1, because they were concerned that the frames might slip, although the frames did not. Most of the subjects habitually wore spectacles, and the reason that groups with larger or wider faces preferred tighter frames was thought to be that they were accustomed to tighter fitting frames.

Adolescent↗

PubMed2003

Inter-generation differences in foot morphology: aging or secular change?

Inter-generation differences in foot dimensions were examined using ANCOVA to determine whether aging or secular change is the more important causal factor. In examining the results, bone size was assumed not to change after the end of linear growth, while foot arches were assumed to become flatter rather than higher if there were any changes in skeletal structure. Changes in overall body build according to age were examined using statistical data collected by the government through population-follow-up. Secular changes in foot length (FL) and foot breadth, diagonal (FB) as well as the changes with age in FB were examined using data measured at ages younger than 50 years. The effects of overall body build were examined using the body mass index (BMI). Compared to the 1970 group (birth year: 1960-78) of the same FL, the 1930 group (birth year: 1909-39) had larger foot circumferences, wider breadth measurements, higher dorsal arches and ball, and greater toe 5 angle, but had shorter fibular instep lengths and shorter 5th metatarsal bones. The 1930 groups tended to have larger FB than the 1970 group of the same foot circumference. No inter-generation differences were observed in the heights at the medial and lateral malleoli, toe 1 angle, or the relationship between FB and heel breadth. These findings are discussed in terms of the effects of weight increase after the end of linear growth, changes in skeletal structure, overall body build as young adults, socioeconomic status during the growth period, as well as differential growth rates of foot bones. The conclusions are 1) changes in foot length and longitudinal arches due to aging are negligible, 2) the large circumferences, breadths, and higher dorsal arches and ball of the 1930 group for their foot length are better explained by their robust bones than by the increase in soft tissue after the end of linear growth, and 3) the larger FB of the 1930 group for their foot circumference is partly explained by their shorter fibular instep length. As a whole, factors affecting growth (secular change) are more important than changes after the end of growth (aging) in the inter-generation differences in foot morphology.

Adolescent↗