Comparison of Two Magnetic Resonance Imaging Contrast Agents Using a Dedicated Veterinary Low-Field Magnet
*M. E. Herrtage, J. Sales, E. A. Baines
The clinical utility of intravenous magnetic resonance (MR) contrast agent administration for improving lesion detection and differential diagnosis is well recognised in human medicine. Most of the MR contrast agents contain gadolinium chelates and a number are commercially available. The purpose of this study was to compare the results from using two different gadolinium-based contrast agents in the diagnosis and assessment of MR images of the head of dogs and cats.
Twenty-seven patients were referred to the Queen's Veterinary School for investigation of a variety of conditions affecting the nasal cavity or brain. MR imaging of the head was performed in each patient under general anaesthesia using a dedicated, low-field MRI unit (Vet-MR®, Esaote) incorporating an open 0.2 Tesla permanent magnet. In each case, the head was placed in a dual phased array coil (143mm x 158mm). T1-weighted, T2-weighted and proton density weighted images of the nasal chambers and paranasal sinuses and/or cranium were acquired in dorsal, transverse and sagittal planes.
T1-weighted images were also acquired immediately following intravenous administration of an MR contrast agent. Nineteen patients received 0.2 mmol/kg gadoteridol (ProHance®, Bracco) and eight patients received 0.1 mmol/kg gadobenate dimeglumine (MultiHance®, Bracco). The images were compared qualitatively for overall image quality, image contrast and degree of enhancement. Safety was evaluated in all patients by means of pre- and post-dose monitoring.
Of the nineteen patients receiving gadoteridol, 15 were dogs and 4 were cats. Thirteen had lesions affecting the brain and six had lesions affecting the nasal cavity. The eight cases which received gadobenate dimeglumine included 6 dogs and 3 cats, of which 5 had brain lesions and 3 had lesions affecting the nasal cavity. Contrast enhancement of the nasal mucosa and of enhancing brain lesions was consistently better following gadobenate dimeglumine administration than with gadoteridol.
Blood pressure, heart rate and respiratory rate did not alter in any of the patients following the administration of the contrast agent apart from one patient where there was a transient increase in heart rate following administration of gadoteridol.
Gadobenate dimeglumine produced improved image contrast and better lesion enhancement at half the dose rate of gadoteridol. Gadobenate dimeglumine administration provided a time-efficient and cost-effective improvement in diagnosis.