Results: For both methods, the attenuation coefficients tend to slightlydecrease (10%) versus administration time. The relative backscattercoefficients show distinctly increased values (10 dB) with a slightlyincrease versus time. These changes are similar to the progression ofthe relevant blood parameters.Conclusions: The results of this study provide useful data about therelations between acoustical parameters, blood levels, and histology ofliver tissue.

OPHTHALMOLOGY

32821

Alternative scattering models for ultrasound parameter imagingof ocular tumorsMargolis R,*1 Rondeau MJ,1,2 Silverman RH,1,2 Folberg R,3 BoldtHC,4 Coleman DJ,1,2 Lizzi FL,5 1. Ophthalmology, WMC of CornellUniversity, New York, NY, 2. Dyson Vision Research Institute, NewYork, NY, 3. Pathology, University of Illinois, Chicago, IL, 4.Ophthalmology and Visual Sciences, University of Iowa, Iowa City,IA, and 5. Biomedical Engineering Directorate, Riverside ResearchInstitute, New York, NY

Objective: We have reported the use of ultrasound parameter imaging(UPI) of ocular melanoma for diagnosis and for clinical staging basedon correlation with extracellular matrix patterns that relate to tumorlethality. The theoretical scattering model underlying UPI is for cali-brated spectrum analysis with focused transducers assuming weakscattering and a spherical ACF to describe the backscatter constituents.In this study, we examine the use of alternate functions for describingscatterers given our histological understanding of 3-D tumor microar-chitecture.Methods: The Cornell-Iowa-Chicago digital RF and pathology data-base was used for this study. A cohort of 117 uveal malignant mela-noma cases with ultrasound scan section matched histology was repro-cessed to obtain UPIs for ellipsoidal and planar scattering functions.UPIs were compared with color-coded digital histology by observersand using image correlation techniques. Of particular interest were theeffects of various ACFs on the spatial distribution of acoustic concen-tration (CQ2) in the tumor periphery.Results: Statistically significant correlations were found between his-tologic and acoustic factors for all ACFs. An improvement in spatiallocalization was seen for ellipsoidal ACFs compared with the sphericalmodel. In the spherical model, correlation coefficients between histo-logic and acoustic parameters were not higher for corresponding zones(i.e., anterior histologic versus anterior acoustic patterns) than in non-corresponding spatial zones (i.e., anterior histologic versus posterioracoustic patterns). Better localization of extracellular matrix patternsallows for improvement in area under the ROC curve.Conclusions: Incorporating a priori knowledge about the tissue scat-tering structure can modify the diagnostic capacity of UPI. The ellip-soidal model may provide better detection of the spatial distribution ofscattering elements associated with high-risk extracellular matrix pat-terns in the tumor periphery.

32778

Three-dimensional high-frequency ultrasound and presbyopiaGuthoff R,*1 Stachs O,1 Martin H,2 Schmitz K,2 1. OphthalmologyDepartment, University of Rostock, Rostock, Germany, and 2.Institute for Biomedical Engineering, University of Rostock, Rostock,Germany

Objective: Presbyopia is the most common refractive disturbance. Theaim of this study was to investigate the benefit of 3D ultrasonic imaging

in combination with FEM calculations to simulate accommodativeprocesses. These experiments may provide further information aboutlens changes during accommodation and may lead to a better under-standing of the role of the lens and the ciliary body changes in theprogression of the presbyopia.Methods: A ultrasound-biomicroscope was extended to the third di-mension to visualize selected structures of the anterior segment of theeye from patients in different accommodation states.Results: The three-dimensional presentation allows an extraction of theciliary muscle from the ciliary body. We are able to distinguish and toanalyse the changes in the muscle contour in different accommodationstates. The calculation of the outer contours of the lens in accommo-dation and desaccommodation was performed using FEM with differ-ent boundary conditions. The change of optical power of the lens canbe computed.Conclusions: The 3D ultrasound biomicroscopy allows an assessmentof the individual ciliary muscle activity in consideration of the ciliaryprocesses. In combination with a contour analysis tool, we improvedthe muscle contour determination during different accommodationstates. These data form a basis for FEM simulations using ABAQUSincluding lens, zonular system, and ciliary body.

32457

Color Doppler flow imaging of orbital vesselsVoskoboynikova N,* Shanina E, Iliasov B, Chugunova I, Nelassov N,Ultrasound Diagnosis, Rostov Regional Medical Therapeutic andDiagnostic Center, Rostov-on-Don, Rostov Province, RussianFederation

Objective: The aim of this study was to evaluate the potential role ofcolor Doppler ultrasonography in the detection of orbital circulatoryabnormalities in glaucoma eyes with different degrees of optic nervedamage and intraocular pressure (IOP).Methods: The ophthalmic artery (OA), central retinal artery (CRA)and vein (CRV), short posterior ciliary artery (SPCA) of 42 patients (76eyes) with glaucoma and 20 control subjects were investigated by colorDoppler imaging (Acuson-Sequoia, Acuson-Aspen; 7.5–10 MHzprobe). Peak systolic and end-diastolic velocities were measured, andresistance index (RI) was calculated.Results: Significant increase of CRA resistance was found in allpatients with glaucoma compared with control group; furthermore, RIwas significantly greater in patients with high IOP than in normal andregulated pressure glaucoma patients (0.94�0.08; 0.78�0.06, respec-tively; p�0.05; control 0.63�0.09; p�0.05). Advanced glaucomatousoptic neuropathy showed significantly decreased peak systolic velocityin nasal SPCA (10�2 cm/s; control 16.2�2 cm/s; p�0.05) and in-creased RI in nasal and temporal SPCA (0.85�0.07; control0.64�0.06; p�0.05). However, patients with less visual field defectshad only significantly increased RI in SPCA (0.78�0.08). There wereno significant differences in SPCA velocity parameters between nor-mal- and high-pressure glaucomatous patients matched for similarvisual field defects. OA velocities and RI were without significantchanges. CRV had significantly increased blood velocity at the laminacribrosa level (18.9�3 cm/s) in patients with high IOP compared withnormal-pressure glaucoma eyes and normal controls (p�0.05).Conclusions: 1) Noninvasive assessment of blood flow in ocularvessels by color Doppler ultrasonography is a valuable method indiagnosis of vascular mechanism of optic neuropathy. 2) All glauco-matous patients had increased RI in CRA, but high-pressure glauco-matous eyes showed significantly greater RI than eyes with normalIOP. 3) Even patients with minimal glaucomatous optic nerve damagehad significantly increased RI in CRA and SPCA. 4) Hemodynamicchanges in CRV at the laminar level were associated with high IOP.

S98 Ultrasound in Medicine and Biology Volume 29, Number 5S, 2003