OTI Scan 1000 Ultrasound Tomography System –
OTI, Canada
Tests Performed with the OTI Scan 1000:
A-Scan/Biometry
The A-scan/Biometry mode of the OTI Scan 1000 Ultrasound Tomography System measures the axial length of an eye. This measurement is taken to determine the power of an intraocular lens (IOL) needed in cataract surgery. Anesthetic drops are necessary since the probe touches the cornea. Examination under anesthesia is required in the pediatric age group.
2D B-Scan Ultrasonography Utilizing a 12 MHz or a 20 MHz (high resolution) B-scan probe attached to the OTI Scan 1000 Ultrasound Tomography System, the B-scan mode images the internal structures of the eye, especially when fundus view is blocked by corneal opacity, cataract or vitreous hemorrhage. It is also used for evaluation of the eye and orbit following traumatic injuries, especially when foreign bodies are involved. This test is also important in ocular or orbital tumor studies, where serial measurements can be taken to observe growth patterns, or where tumor recurrence can be monitored in treated cases.
The ultrasound images generated may be in regular still format or short dynamic video clips. Dynamic video clips are important in evaluating the structure of a lesion, examining the nature of tissue movement, and checking for the presence of internal
vascularity. Again, utmost patient cooperation is needed, and examination under anesthesia is ideal in the pediatric age group.
Case 1. This is a serial follow-up of choroidal melanoma after plaque therapy showing tumor height and base
measurements:
A. previous study (high resolution views)
B. subsequent study (magnified high resolution views). Note decrease in tumor height on vertical views.
Case 2. This is a serial follow-up of choroidal melanoma after plaque therapy showing tumor height and base
measurements:
A. previous study (high resolution views)
B. subsequent study (magnified high resolution views). Note decrease in tumor height on vertical and transverse views.
This is vitreous hemorrhage with posterior vitreous detachment
demonstrating wave-like, undulating aftermovement.
This is a dislocated cataract floating in the vitreous.
This is posterior vitreous detachment with
open funnel retinal detachment. The vitreous exhibits wave-like,
undulating aftermovement, while the retina displays shaky, jiggly
aftermovement.
This is a bi-lobed, dome-shaped serous choroidal detachment showing no
aftermovement
This is a tri-lobed, dome-shaped kissing type of hemorrhagic choroidal
detachment associated with retinal detachment. Blood moves within the
choroid, but there is no movement of the choroid and retina.
3D B-Scan Ultrasonography Aside from its regular A-scan/Biometry and 2D B-scan capabilities, the OTI Scan 1000 Ultrasound Tomography System performs 3-dimensional tomographic imaging of the eye and orbit. Ninety-seven serial 2D B-scans rotating 360 degrees around the central axis of the eye produce an interactive volumetric 3D image block of the eye, enabling clinicians to view internal structures of the eye and orbit in perspectives never before possible with 2D B-scan
ultrasonography.
Optic nerve sheath diameter study using posterior coronal view obtained by 3D
ultrasonography.
3D ultrasound imaging allows volumetric and topographic reconstruction of the vitreous, retina,
choroid, sclera, and orbital structures. Volumetric reconstruction is valuable in tumor growth assessment, while topographic mapping provides a more comprehensive quantitative description of the surface and marginal parameters responsible for volumetric changes.
Volumetric
Estimation and Topographic Reconstruction of Optic Disc
In either 2D or 3D format, regular ultrasound images are not easy to comprehend as they consist solely of piecemeal profiles and cross-sections. Surface rendering of 3D ultrasound images is a novel way of imaging ophthalmic pathologies in vivo, revealing valuable topographic information in ways more familiar and recognizable to the untrained eye, where surfaces can be perceived and their approximate relationships in three dimensions can be presented (e.g. to determine the contour and size of tumors, to ascertain the shape and relative configurations of tissues and structures in the eye). It may have a useful role in ophthalmology if it can enhance understanding of 3D ultrasound images by the viewer, referring physicians and patients.
Surface rendering example of choroidal melanoma with retinal detachment inferiorly. A radioactive plaque is placed on the sclera centered on the
lesion:
A. 3D ultrasound anteronasal view
B. surface rendered 3D ultrasound anteronasal view
C-E. surface rendered anterior coronal views of the mass
F. 3D ultrasound posteronasal view
G. surface rendered 3D ultrasound posteronasal view
H. surface rendered view of the radioactive plaque behind the eyeball.
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