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Biomedical subjects

Lisa M F Thain

Publications and source records attributed to Lisa M F Thain.

5 recordsLinked to original sources
PubMed2004

High-resolution MRI and micro-CT in an ex vivo rabbit anterior cruciate ligament transection model of osteoarthritis.

OBJECTIVE: The aim of this study was to investigate the potential of using non-invasive, multi-modality imaging techniques to quantify disease progression in a rabbit model of experimentally induced osteoarthritis (OA). METHODS: High-resolution 4-T magnetic resonance imaging (MRI) and micro-computed tomography (micro-CT) techniques were implemented and validated in an ex vivo rabbit anterior cruciate ligament transection (ACLT) model of OA. A three-dimensional (3-D) rigid body registration technique was executed and evaluated to allow combined MR-CT analysis in co-registered image volumes of the knee. RESULTS: The 3-D MRI and micro-CT data formats made it possible to quantify cartilage damage, joint-space, and osseous changes in the rabbit ACLT model of OA. Spoiled gradient-recalled echo and fast-spin echo (FSE) sequences were jointly used to evaluate femorotibial cartilage and determine the sensitivity (78.3%) and specificity (95.3%) of 4-T MRI to detect clinically significant cartilage lesions. Overall precision error of the micro-CT technique for analysis of joint-space, volumetric bone mineral density (vBMD), and bone volume fraction (BV/TV) was 1.8%, 1.2%, and 2.0%, respectively. Co-registration of the 3-D data sets was achieved to within 0.36 mm for completed intermodality registrations, 0.22 mm for extrapolated intramodality registrations, and 0.50mm for extrapolated intermodality registrations. CONCLUSIONS: These results indicate that high-resolution 4-T MRI and micro-CT can be used to accurately quantify cartilage damage and calcified tissue changes in the rabbit ACLT model of OA. In addition, image volumes can be successfully co-registered to facilitate a comprehensive multi-modality examination of localized changes in both soft tissue and bone within the rabbit femorotibial joint.

Animals↗
PubMed2004

Ex vivo characterization of articular cartilage and bone lesions in a rabbit ACL transection model of osteoarthritis using MRI and micro-CT.

OBJECTIVE: To characterize the rabbit anterior cruciate ligament transection (ACLT) model of osteoarthritis (OA) at various stages of disease using high-resolution 3-D medical imaging systems, which, in turn, will facilitate future longitudinal studies evaluating disease progression and response to therapy in live animals. METHODS: Degenerative changes in femorotibial cartilage, volumetric bone mineral density (vBMD), bone volume fraction (BV/TV), and osteophyte volume were characterized ex vivo using 4-T magnetic resonance imaging (MRI) and micro-computed tomography (micro-CT) at 4, 8, and 12 weeks post-ACLT. These changes were subsequently correlated to macroscopic joint evaluation. RESULTS: Macroscopic assessment demonstrated progressive cartilage degeneration post-surgery, which was significantly correlated to MRI evaluation (r=0.82, P<0.0001). Linear regression analysis indicated that vBMD and BV/TV are linearly related such that as vBMD increases, BV/TV increases (P<0.0001). Micro-CT revealed bone loss at 4 and 8 weeks post-ACLT, but recovery to control values at 12 weeks post-ACLT. Volumetric BMD was not strongly correlated with macroscopic assessment of articular cartilage degeneration (r=-0.35, P<0.0001). Quantitative measurement of osteophyte volume demonstrated a statistically significant difference (with respect to control groups) at both 8 and 12 weeks post-ACLT, but not at 4 weeks post-ACLT. CONCLUSIONS: The rabbit ACLT model of OA demonstrates progressive cartilage degeneration and intermediate bone changes at 4, 8, and 12 weeks post-surgery. Cartilage and bone lesions were characterized ex vivo using 4-T MRI and micro-CT, and MRI assessment of cartilage degeneration was correlated to macroscopic grading.

Animals↗
PubMed2002

Sonography of peripheral nerves: technique, anatomy, and pathology.

Sonography provides a unique method for evaluating peripheral nerves because of its high spatial resolution, its ability to follow structures over long distances in a limb, and its dynamic nature that allows movement of patient and transducer. When combined with the wide availability and relatively low cost, sonography is an excellent modality for peripheral nerve assessment. The authors review the techniques used in assessment of peripheral nerves, the relevant anatomy, and common pathologic processes.

Journal Article↗
PubMed2002

Posterior ankle arthroscopy: an anatomic study.

BACKGROUND: Ankle arthroscopy has generally been performed with use of anterior portals with the patient in the supine position. Little has been published on ankle arthroscopy performed with use of posterior portals, particularly with the patient in the prone position. The purpose of the present study was to evaluate the relative safety and efficacy of ankle arthroscopy with use of posterior portals with the limb in the prone position. METHODS: Thirteen fresh-frozen cadaver specimens were used. Posterolateral and posteromedial portals were established. Arthroscopy was performed, and the extent of the talar dome that could be visualized was marked. Four-millimeter plastic cannulae were filled with oil and were placed in the portals for use as reference landmarks on magnetic resonance imaging studies. The proximity of the portal cannulae to the adjacent structures was measured on standard magnetic resonance images and then during careful dissection. The distances measured by dissection were compared with the measurements made on magnetic resonance images. RESULTS: An average of 54% (range, 42% to 73%) of the talar dome could be visualized. The average distance between a cannula and adjacent anatomic structures after dissection was 3.2 mm (range, 0 to 8.9 mm) to the sural nerve, 4.8 mm (range, 0 to 11.0 mm) to the small saphenous vein, 6.4 mm (range, 0 to 16.2 mm) to the tibial nerve, 9.6 mm (range, 2.4 to 20.1 mm) to the posterior tibial artery, 17 mm (range, 19 to 31 mm) to the medial calcaneal nerve, and 2.7 mm (range, 0 to 11.2 mm) to the flexor hallucis longus tendon. The magnetic resonance images demonstrated very similar distances except in the case of the distance between the posteromedial cannula and the tibial nerve, which often was difficult to specifically identify on magnetic resonance imaging studies. CONCLUSIONS: The findings of the present cadaveric study suggest that, with the patient in the prone position, arthroscopic equipment may be introduced into the posterior aspect of the ankle without gross injury to the posterior neurovascular structures. Limited clinical trials should be carried out to confirm this finding.

Ankle Injuries↗