The Difference of Contrast Effects of Myelography in Normal Dogs: Comparison of Iohexol (180mgI/ml), Iohexol (240mgI/ml) and Iotrolan (240mgI/ml)

Abstract

ABSTRACT. The contrast effects of three different contrast media preparations (iohexol 180 mgI/ml, iohexol 240 mgI/ml and iotrolan 240 mgI/ml) in conventional and CT myelography were compared. Three beagle dogs were used and the study employed a cross-over method (total of 9) for each contrast media. The result of CT myelography showed that the contrast effect of iohexol (180 mgI/ml), which had low viscosity, was highest in cranial sites, and the contrast effect of high-viscosity iotrolan (240 mgI/ml) was highest in caudal sites 5 min after injection of the contrast media preparations. This shows that the diffusion of contrast media preparations in the subarachnoid space is influenced by viscosity. The results of conventional myelography also showed that the diffusion of contrast media preparations is influenced by viscosity. Therefore, it is important to identify the location of spinal lesions in veterinary practice, and low viscosity contrast medium preparation with wide spread contrast effects is considered suitable for myelography. KEY WORDS: CT, iohexol, iotrolan, myelography, viscosity.J. Vet. Med. Sci. 70 (7): [659][660][661][662][663] 2008 Myelography is the radiographic examination of the spinal cord following injection of contrast medium into the subarachnoid space. Not only the existence but also the location of spinal lesions can be diagnosed by myelography. [5,12] In veterinary science, it is very important to identify the location of a spinal lesion because determination of the clinical lesion is difficult by neurological examination alone. Myelograms used to be taken after the injection of contrast medium but recently the use of computed tomography (CT) has become widespread when diagnosing spinal diseases. In Japan, iohexol and iotrolan are approved by the Ministry of Health, Labor, and Welfare as contrast media for myelography. Contrast media preparations with high iodine concentrations are often also used for myelography in small animal practice [2,3,6,9,10], however, high-iodineconcentration contrast media preparations often give insufficient contrast effects because of their limited diffusion. The concentration of iodine and the viscosity of contrast media preparations vary, and therefore, the contrast effects can differ [10]. The contrast resolution of CT is different from that of conventional radiography [4], so selection of contrast media preparations for myelography should be considered carefully. In this study, the contrast effects of three different contrast media preparations were examined by conventional and CT myelography. MATERIALS AND METHODS Contrast media preparations:Iohexol 180 mgI/ml (Omnipaque ® 180, Daiichi Sankyo Company Limited, Tokyo, Japan), iohexol 240 mgI/ml (Omnipaque ® 240) and iotrolan 240 mgI/ml (Isovist ® Inj. 240, Bayer Yakuhin, Limited, Osaka, Japan) were used in this study. The molecular weight of iohexol is 821.4 (monomeric), and iotrolan is 1626.24 (dimeric). Viscosity (at 37°C) of iohexol 180 mgI/ ml is 2.0 mPa⋅s, iohexol 240 mgI/ml is 3.3 mPa⋅s, and iotr...

Comparison of the diagnosis of intervertebral disc herniation in dogs by CT before and after contrast enhancement of the subarachnoid space

“…The dogs were placed in a dorsal recumbent position during the initial scans of the T3 to L7 vertebrae, depending on the results of the neurological examination. A lumbar puncture was then performed percutaneously through the L5 to L6 interarcuate foramen, and the prewarmed contrast medium, iohexol (Omnipaque 180; Daiichi Sankyo) was administered at a dose of 0·45 ml/kg to each dog (Shimizu and others 2008). After rolling the dog, it was scanned again.…”

Diagnostic Imaging in Intervertebral Disc Disease

“…In order to achieve a diagnostic myelographic study, several technical aspects are important. Non-ionic, iodinated, watersoluble contrast agents such as iohexol, iopamiron, or iotrolan, with concentrations ranging from 180 to 240 mg/ml, ideally at body temperature, should be used (42). Injection sites can be either the cerebellomedullary cistern or lumbar region, although lumbar myelography is superior, especially for investigating the thoracolumbar region (21,43).…”

Incidence of and risk factors for seizures after myelography performed with iohexol in dogs: 503 cases (2002–2004)

“…11,12 Because of the high risk of postmyelographic seizures with the use of metrizamide, second-generation nonionic contrast agents such as iopamidol and iohexol were introduced, followed more recently by newer contrast agents such as iotrolan and iomeprol. 5,[13][14][15] Among all contrast media for myelography in dogs, iohexol appears to be the most commonly used. As for its predecessor, metrizamide, the use of iohexol for myelography is associated with seizures.…”