Stability of gold bead tissue markers

Abstract

Significant soft tissue features in the orbit and elsewhere are not resolved by MRI or any other imaging method. We describe a new method that uses tiny ( approximately 0.1 mm diameter) gold beads as markers to visualize movements of such tissues with high spatial resolution ( approximately 100 microm) and moderate temporal resolution ( approximately 100 ms). We describe bead fabrication, implantation, imaging, and image processing to extract three-dimensional bead coordinates. We then present results of an experiment to determine the stability of gold bead tissue markers (GBTMs) over time in normally moving orbital tissues. Most beads (76%) implanted in sclera, muscle, tendon, and connective tissue were highly stable over the 6-month measurement period. Beads that were judged unstable drifted only a few 100 microm. Bead flows with gaze suggested that posterior Tenon's capsule moves with the globe, that the lateral rectus belly may sideslip, producing "bridle forces," and that the posterior medial rectus pulley sling moves freely anteriorly and posteriorly, but hardly vertically, as required by the "coordinated active pulley" hypothesis. The GBTM method seems applicable to study such short time course phenomena as extraocular muscle (EOM) and connective tissue movement as a function of gaze and such long time course phenomena as myopic eye growth.

Physically-based modeling and simulation of extraocular muscles

“…Extraocular muscle deformation as a function of gaze and time is an important parameter in studying extraocular mechanics [Miller et al, 2006]. We validate the dynamic EOM deformation of our model by comparing simulation to the in vivo EOM motion data.…”

Longitudinal strain estimation in incompressible cylindrical tissues from magnetic resonance imaging

“…However, measuring EOM deformation is challenging. Miller et al [17] implanted gold beads in the orbits of monkeys and tracked these markers using CT imaging. Clearly, this technique cannot be used on human subjects.…”

“…Dye lines of elastin stain were applied on the gastrocnemius tendon-muscle unit for measuring longitudinal strain [14]. Markers have been attached to the surfaces of tendon and muscle [15], [16], [4] or implanted in extraocular muscles [17]. The surface markers are limited to the study of cadaver tissues or superficial live tissues.…”

It seemed like a good idea at the time: A brief history of Journal of Vision

“…Among these were "Are faces are processed like words?" (Martelli, Majaj, & Pelli, 2005), "Gold Beads Show Previously Unseen Parts of the Eye" (Miller, Rossi, Wiesmair, Alexander, & Gallo, 2006), "Virtual Forest Used to Measure Navigation Skills" (Fortenbaugh, Hicks, Hao, & Turano, 2006), "Are Angry Women More Like Men" (Hess, Adams, Grammer, & Kleck, 2009), "Can We Learn to See" (Schwiedrzik, Singer, & Melloni, 2009).…”