Serum biochemical response to contrast media administration in anaesthetised dogs

Use of the bolus tracking technique for the tomographic evaluation of the uretero-vesicular junction in dogs and assessment of dose records

BACKGROUND

The aim of the work is the application of a bolus tracking technique for tomographic evaluation of the uretero-vesicular junction in dogs. Ten adult dogs (8-14 years) with variable body weight (2,8-32 kg) were enrolled in the prospective study. The patients were placed in sternal recumbency with a 10° elevated pelvis and the visualization of the uretero-vesicular junction was obtained with the bolus tracking technique after intravenous administration of non-ionic contrast medium. In the post-contrast late phase a region of interest was placed within the lumen of the distal ureters and the density values were monitored before starting the helical scan.

RESULTS

The uretero-vesicular junction was clearly visible in 100% of patients with the visualization of the endoluminal ureteral contrast enhancement and bladder washout. At the end of the tomographic study an evaluation of the dose records was performed and compared to human exposures reported in literature for the pelvic region. The effective dose estimated for each patient (37,5-138 mSv) proved to be elevated, when compared to those reported in human patients.

CONCLUSION

The bolus tracking technique could be applied for the visualization of the uretero-vesicular junction in non-pathological patients, placing the region of interest in the distal ureters. The high effective doses recorded in our study support the need of specific thresholds for veterinary patients, pointing out the attention for paediatric patient's exposure also in veterinary imaging.

Exclusion of a brain lesion: is intravenous contrast administration required after normal precontrast magnetic resonance imaging?

Background

No evidence‐based guidelines are available for the administration of gadolinium‐based contrast media to veterinary patients.

Objective

To investigate whether administration of intravenous (IV) contrast media alters the likelihood of identifying a brain lesion in dogs and cats.

Animals

Four hundred and eighty‐seven client‐owned animals referred for investigation of intracranial disease.

Methods

Two reviewers retrospectively analyzed precontrast transverse and sagittal T1‐weighted (T1W), T2‐weighted, and fluid‐attenuated inversion recovery low‐field MRI sequences from each patient for the presence of a clinically relevant brain lesion. All sequences subsequently were reviewed in the same manner with additional access to postcontrast T1W images.

Results

Of the 487 precontrast MRI studies, 312 were judged to be normal by 1 or both reviewers. Of these 312 studies, a previously undetected lesion was identified in only 6 cases (1.9%) based on changes observed on postcontrast sequences. Final diagnoses included meningoencephalitis of unknown origin (n = 1), feline infectious peritonitis (n = 1), and neoplasia (n = 2). All 4 of these cases had persistent neurological deficits suggestive of an underlying brain lesion. Contrast enhancement observed in the 2 other cases was considered falsely positive based on the results of further investigations.

Conclusions and Clinical Importance

In patients with normal neurological examination and normal precontrast MRI, the subsequent administration of IV gadolinium‐based contrast media is highly unlikely to disclose a previously unidentified lesion, calling into question the routine administration of contrast media to these patients. However, administration still should be considered in animals with persistent neurological deficits suggestive of an underlying inflammatory or neoplastic brain lesion.