Objective—To assess the impact of cycles of freezing and thawing on magnetic resonance (MR) images (obtained by use of a 3-T magnet) of equine feet examined ex vivo.
Sample—9 forelimbs from 9 horse cadavers.
Procedures—9 forefeet underwent MR imaging first at ambient temperature within 12 hours after the horses' death and then after each freezing-thawing cycle. Three digits underwent freezing and thawing (at 4°C for 36 hours) 2 times, 3 digits underwent freezing and thawing (at 4°C for 36 hours) once and rescanning after 24 hours at ambient temperature, and 3 digits underwent freezing and thawing at ambient temperature for 24 hours once. Images of the digits obtained prior to freezing were subjectively compared with images obtained after freezing and thawing. Changes in the signal-to-noise ratio between examinations were assessed.
Results—Overall image quality was considered unchanged except for the hoof capsule. Quantitative analysis revealed signal-to-noise ratio changes in bone marrow, soft tissues, and hoof capsule induced with both thawing processes. The signal-to-noise ratio in the sy-novial recess of the distal interphalangeal joint significantly increased as a result of thawing at4°C.
Conclusions and Clinical Relevance—Although overall image quality was considered unchanged except for the hoof capsule, results suggested that changes induced in cadaver limbs following freezing and thawing, which are probably attributable both to modified and inhomogeneous temperature distribution and direct tissue damage, may alter the reliability of signal intensity in ex vivo MR examinations.
Objective—To determine radiographic, magnetic resonance
imaging (MRI), computed tomography (CT),
and rhinoscopic features of nasal aspergillosis in
Animals—15 client-owned dogs.
Procedure—All dogs had clinical signs of chronic
nasal disease; the diagnosis of nasal aspergillosis was
made on the basis of positive results for at least 2
diagnostic tests (serology, cytology, histology, or fungal
culture) and detection of typical intrasinusal and
intranasal fungal colonies and turbinate destruction
via rhinoscopy. Radiography, MRI, and CT were performed
under general anesthesia. Rhinoscopy was
repeated to evaluate lesions and initiate treatment.
Findings of radiography, MRI, CT, and rhinoscopy
Results—MRI and CT revealed lesions suggestive of
nasal aspergillosis more frequently than did radiography.
Computed tomography was the best technique for
detection of cortical bone lesions; the nature of abnormal
soft tissue, however, could not be identified.
Magnetic resonance imaging allowed evaluation of
lesions of the frontal bone and was especially useful for
differentiating between a thickened mucosa and secretions
or fungal colonies; however, fungal colonies could
not be differentiated from secretions. Rhinoscopy
allowed identification of the nature of intranasal and
intrasinusal soft tissue but was not as useful as CT and
MRI for defining the extent of lesions and provided no
information regarding bone lesions.
Conclusions and Clinical Relevance—The value of
CT and MRI for diagnosis of nasal aspergillosis was
similar and greater than that of radiography.
Rhinoscopy is necessary because it is the only technique
that allows direct visualization of fungal
colonies. (J Am Vet Med Assoc 2004;225:1703–1712)