The effect of axial and abaxial release on meniscal displacement in the dog.

The meniscal release (MR) is used to minimize meniscal pathology after Tibial Plateau Leveling Osteotomy (TPLO) surgery. The purposes of this study were: (i) to describe meniscal orientation in a unaltered cadaveric canine stifle, a cruciate deficient stifle, TPLO repaired stifle with and without the MR using magnetic resonance imaging; (ii) to determine if the abaxial release is equivalent to the axial release in its ability to affect caudal pole displacement in a TPLO repaired stifle and (iii) to evaluate with MRI the effect of MR on the femorotibiol articular cartilage contact area in a TPLO repaired stifle. Briefly, cadaver limbs were placed into a jig designed to mimic a weight-bearing stance at 140 degrees and 90 degrees at the stifle. The limbs were sequentially evaluated from the unaltered state; after cranial cruciate ligament transection; after TPLO stabilization; and finally after a meniscal release. No significant difference was found between the intrameniscal area (IMA) of the abaxial and axial meniscal releases although there was an increase in the IMA after the meniscal release compared to the IMA in the normal, cranial cruciate ligament deficient stifle, and TPLO stabilized stifle. In the abaxial release, a meniscal remnant remained in situ and provided a space effect between the femur and the tibial plateau. This is in contrast to the axial meniscal release, where the entire caudal pole of the medial meniscus relocated caudolaterally and consequently permitted more direct femorotibial contact. Overall, however, there was evidence of caudal pole compression of the medial meniscus throughout the MRI series which was ameliorated by either of the MR procedures.

Contrast enhancement in magnetic resonance imaging using intravenous paramagnetic contrast media: a review.

Interest in magnetic resonance (MR) imaging as a major diagnostic tool in veterinary clinical medicine is increasing. Most MR studies are performed with the use of contrast enhancement via intravenous injection of paramagnetic gadolinium-containing contrast media. A vast number of publications are available regarding the use of contrast media in humans. The purpose of this paper is to assist practicing veterinary radiologists in understanding mechanisms of MR contrast enhancement. This paper reviews certain aspects of MR contrast enhancement, including physical, chemical and biologic characteristics of most common MR contrast media targeted primarily at the central nervous system (CNS). Authors also describe processes that explain changes in signal intensity on the MR images.

Computed axial tomography of the porcine nasal cavity and a morphometric comparison of the nasal turbinates with other visualization techniques.

A non-invasive imaging modality, computed tomography (CT), was used to visualize changes in nasal turbinates of anesthetized pigs over a 12-week observation period (pigs were 14 wk of age at study week 0). Normal, non-infected pigs were compared to pigs with mild challenge-induced atrophic rhinitis (AR) in order to detect subtle differences in morphology. To determine feasibility for time course studies in future experiments, morphometric quantitation at the level of the 2nd premolar (turbinate area ratio or TAR) in cross-section CT images at multiple timepoints was done. Additionally, at study termination, the TAR determined from CT images, magnetic resonance imaging (MRI), and wet tissue (WT), were compared to each other and to the standard subjective measure, visual scoring. There were no statistically significant differences between the control and AR groups at CT imaging dates of 0, 3, 6, 9, or 12 wk (P = 0.182). However, a statistically significant decrease in TAR measurements over time (P = 0.015) was observed in both groups, with lower mean values observed on Weeks 3 and 6 before rebounding to baseline values at study termination. At Week 12 (termination of the study), the TAR measurements derived from CT, MRI, and WT were not statistically different from one another (P = 0.220) and the treatment group-by-method interaction was not significant (P = 0.800). This provided evidence of equivalency of the techniques. Mean values for normal and infected groups were not significantly different based on either TAR imaging methods (P = 0.552) or visual scores (P = 0.088). Thus, the current study demonstrated that CT was an acceptable alternative imaging modality which could be used for quantitation of turbinate changes in snouts of live pigs to provide data comparable to tissue taken at necropsy. Computed tomographic imaging would allow non-invasive tracking of disease or treatment responses within individual animals over time. Morphometric analysis of the TAR was equivalent between the CT, MRI, and WT specimens.

Molecular diffusion and DNP enhancement in aqueous char suspensions.

The heterogeneous 1H dynamic nuclear polarization (DNP) effect is studied at low magnetic fields for a system consisting of several newly synthesized carbon chars suspended in water. By using Fourier Transform pulsed-field-gradient spin-echo NMR spectroscopy, several different self-diffusion coefficients have been observed in aqueous char suspensions, corresponding to regions of differing water mobility in the porous structure. Proton spin-lattice relaxation data generally confirm the results of molecular diffusion measurements. Through utilization of the Torrey model, the influence of "cage effects" on DNP enhancement in porous media is discussed. Results suggest that short-range nuclear-electronic interactions in pores have a dominant effect on DNP enhancement in char suspensions.

Computed tomography of the normal feline nasal cavity and paranasal sinuses.

Computed tomography (CT) images of the feline nasal cavity and paranasal sinuses were acquired from normal adult cats. Good resolution and anatomic detail were obtained from the CT images using soft tissue formatting. A description of normal feline nasal cavity and paranasal sinus anatomy using CT is presented.

Magnetic resonance imaging of the equine metacarpophalangeal joint: three-dimensional reconstruction and anatomic analysis.

Magnetic resonance imaging was used to examine the equine metacarpophalangeal joint. Thirty-two saggital images generated by partial volume imaging were transferred to a computer for three-dimensional reconstruction and analysis. All the tissues constituting the metacarpophalangeal joint were readily identified. The most significant increase finding regarded the soft tissues on the palmar aspect of the metacarpophalangeal joint and their interactions with the proximal sesamoid bones. The equine metacarpophalangeal joint has not previously been evaluated using 3-dimensional imaging software.

Correlation between anatomic features and low-field magnetic resonance imaging of the equine metacarpophalangeal joint.

OBJECTIVE: To expand our current knowledge and to establish limits of correlation between signal intensities of the magnetic resonance (MR) image and actual macroscopic and microscopic anatomic features of the imaged structures of the equine metacarpophalangeal joint (MCPJ). SAMPLE POPULATION: The right MCPJ was obtained from 4 adult horses that were euthanatized for reasons unrelated to the musculoskeletal system. PROCEDURE: The distal portion of the right forelimbs was collected from 4 equine cadavers. The bones were drilled to provide fixed reference points and examined by MR imaging. After imaging, the joints were sectioned for gross and histologic inspection. The MR images were aligned and correlated with digitized gross and histologic images to identify tissue types. RESULTS: Comparison of the images resulted in identification of different bone types, articular cartilage, and soft tissue structures of the equine MCPJ. CONCLUSION: Results provided relevant information regarding the appearance of the imaged tissues of the equine MCPJ. CLINICAL RELEVANCE: Although MR imaging does not have current clinical applications for equine practitioners, its wide acceptance as the imaging modality used for most human musculoskeletal derangements may aid in developing more realistic applications in equine medicine.

[Competitive interrelations between bilirubin and x-ray contrast agents in binding with human serum albumin]. / Issledovanie konkurentnykh vzaimootnoshenii mezhdu bilirubinom i rentgenokontrastnymi sredstvami pri ikh sviazyvanii s syvorotochnym al'buminom cheloveka.

It was shown that bilirubin can be a fluorescent probe for human serum albumin. Parameters of the interaction of bilirubin with albumin were determined. It was found that bilimin and iopanoate decrease affinity of bilirubin to strongly and poorly binding areas of human serum albumin, biliognost and endobil predominantly to its poorly binding sites, and iodamide and verografin exert no influence on binding of bilirubin with albumin. It is concluded that in the clinical practice it is necessary to take into consideration the possibility of an increase in the blood level of free bilirubin in patients during cholecystography with the use of contrast media.