Dasom Kim

Electron Tomography and Synapse Study

Electron tomography (ET) is a useful tool to investigate threedimensional (3D) details based on virtual slices of relative thick specimen. A single electron transmission microscopic image is to ET what single X-ray image is to computed X-ray tomography (Rhyu & Park, 2008). As computed X-ray tomographic image shows cross sectional information of the body without real sectioning in hospital, we can get virtual cross sectional image of relative thick specimen up to resolution 2.4 A recently (Scout et al., 2012). Not only technical upgrade of ET, but sophisticated analyses of various specimens are main interest of electron tomographic studies (Frey et al., 2006; Mun et al., 2008; Jou et al., 2013). By using relative thick specimen and very thin virtual slice up to 1 nm, ET is a useful tool dissecting very small structures and relatively large structures at the same time. PRINCIPLES OF ELECTRON TOMOGRAPHY

A Method of Radial Nerve Length Measurement Based on Cadaveric Investigation.

OBJECTIVE To determine the most reliable method to measure the length of the radial nerve during a nerve conduction study (NCS). DESIGN Cadaveric investigation. SETTING A practical anatomy research laboratory in a university. PARTICIPANTS Fresh cadavers (N=10), with 1 cadaver for study design and 9 for data. INTERVENTIONS Design of measurement methods using cadaver dissection and comparison of the measured values to the true length in 18 arms of 9 cadavers. MAIN OUTCOME MEASURES Four points (A, B, C, D) were determined: (A) proximal stimulation point in NCS; (B) point at the elbow crease; (C) point in the midforearm; and (D) distal stimulation point 5cm above the extensor indicis. The true length of the radial nerve between the stimulus points (points A and D) in NCS was compared with the measured values by summation of the straight line segments between those points with various combinations. The difference in root mean square error (RMSE) of the distance measured by each method compared with the true length was calculated to determine the best measurement method. RESULTS The closest distance to the true length (28.7±2.8cm) in the cadaveric investigation was obtained using the summation of straight line segments between points A, B, and D (A-B-D, RMSE=.72cm), followed by the A-B-C-D distance (RMSE=.87cm) and the A-D distance (RMSE=1.38cm) methods, in sequence. The former 2 distance measurements were relatively closer to the true length than the latter measurement method. CONCLUSIONS Multiple segmentation measurement methods reflected the course of the radial nerve better than a single linear measurement method. We suggest that the distance measured using a stopover point near the lateral epicondyle between 2 stimulus points (A-B-D distance) is closer to the true length of the nerve.

Effects of body size on cranial capacity in Korean youth

Cranial capacity is an important parameter in the fields of evolutionary biology and anthropology and is closely related to brain size. Owing to modern imaging technologies such as computed tomography and magnetic resonance imaging (MRI), the exact measurement of cranial capacity is possible. Our group has reported the effects of body size on brain size in Korean youths based on MRI volumetry. However, the effects of body size on cranial capacity and related analyses have not yet been reported in a Korean population. In this study, we constructed three-dimensional models of the intracranial cavities of young Koreans and calculated the volumes. We evaluated the relations of stature and body weight with cranial capacity and analyzed the correlation of cranial capacity with brain volume. Stepwise linear regression showed that body height is a key parameter contributing to cranial capacity, which is expressed by the following equation: (intracranial capacity, cm3) = (11.440 × body height) – 420.03, R2 = 0.51. The correlation between intracranial cavity volume and brain volume was strong (r = 0.89), which allowed us to calculate an equation for brain volume based on intracranial cavity volume.

Optimal Placement of Needle Electromyography in Extensor Indicis: A Cadaveric Study

Objective To identify the center of extensor indicis (EI) muscle through cadaver dissection and compare the accuracy of different techniques for needle electromyography (EMG) electrode insertion. Methods Eighteen upper limbs of 10 adult cadavers were dissected. The center of trigonal EI muscle was defined as the point where the three medians of the triangle intersect. Three different needle electrode insertion techniques were introduced: M1, 2.5 cm above the lower border of ulnar styloid process (USP), lateral aspect of the ulna; M2, 2 finger breadths (FB) proximal to USP, lateral aspect of the ulna; and M3, distal fourth of the forearm, lateral aspect of the ulna. The distance from USP to the center (X) parallel to the line between radial head to USP, and from medial border of ulna to the center (Y) were measured. The distances between 3 different points (M1– M3) and the center were measured (marked as D1, D2, and D3, respectively). Results The median value of X was 48.3 mm and that of Y was 7.2 mm. The median values of D1, D2 and D3 were 23.3 mm, 13.3 mm and 9.0 mm, respectively. Conclusion The center of EI muscle is located approximately 4.8 cm proximal to USP level and 7.2 mm lateral to the medial border of the ulna. Among the three methods, the technique placing the needle electrode at distal fourth of the forearm and lateral to the radial side of the ulna bone (M3) is the most accurate and closest to the center of the EI muscle.