Pharmacokinetics of contrast media: experimental results in dog and man with CT implications.

The pharmacokinetics of contrast media such as sodium iocarmate, sodium ioxithalamate, metrizamide, sodium/meglumine diatrizoate, and sodium ioxaglate (a recently introduced medium: a hexaiodinated monoacid dimer) was compared in 25 dogs. A biphasic phenomenon was observed due to the rapid diffusion of contrast media from plasma into tissue (interstitium) followed by slow urinary excretion. A bicompartmental analysis was performed in dogs for each agent, showing that the tissue distribution of ioxithalamate is higher than that of other media. Sodium/meglumine ioxithalamate, sodium iocarmate, and sodium/meglumine ioxaglate were also compared in 20 human subjects. The diffusion and excretion phases observed in man appear to be slower than in the dog. Significant variations of iodine plasma concentration from one patient to another were recorded for the same medium and at the same interval after injection. Significant differences were observed between ioxithalamate and iocarmate or ioxaglate plasma concentrations due to the greater tissue diffusibility of ioxithalamate. The mechanisms affecting contrast media diffusibility are discussed: osmolarity, liposolubility, protein binding, and molecular size. Variations in contrast medium concentration in plasma noted in different patients with the same medium are explained by variations in tissue distribution, contrast medium volume, patient age, and patient hydration. Some computed tomographic (CT) implications of these pharmacokinetic studies are discussed. The need for highly diffusible media in routine CT and for less diffusible media in CT angiography is emphasized.

[The value of computerized tomography in the exploration and surveillance of diencephalic tumours (4 cases) (author's transl)]. / La tomodensitométrie dans l'exploration et la surveillance des tumeurs diencéphaliques. 4 cas.

Computerized tomography has transformed the protocol of exploration and surveillance of diencephalic tumours. It gives information concerning their structure, extension and all associated pathology. In addition, the examination is non-traumatic for the patient which in most cases makes it possible to avoid classical neuroradiological procedures with contrast medium, and may be repeated in order to observe the course of these tumours after radiotherapy. Four cases are reported to illustrate the different contributions of CT scanning.

[Comparison of CT, scintigraphy, and angiography in the topographic and pathological diagnosis of 300 supratentorial tumors (author's transl)]. / Comparaison des tomodensitométrie, cinégammagraphie, et angiographie dans les diagnostics topographique et histologique pré-opératoires de 300 tumeurs intracrániennes sus-tentorielles.

The results of CT, scintigraphy (CSS), and angiography in 300 supratentorial cerebral tumors were compared with regard to the topographic and pathological diagnosis proposed in the initial reports. CT elucidated the topography in 98% of the cases and the pathology in variable percentages, depending on the type of tumor. The use of scintigraphy provided a high accuracy of pathological diagnosis. Except for meningiomas, arteriography was less accurate than the two other methods of examination. A radiological management of supratentorial cerebral tumors is proposed based on clinical and CT data.