CONTRAST-ENHANCED MAGNETIC-RESONANCE ANGIOGRAPHY OF PERIPHERAL VESSELS - DIFFERENT CONTRAST AGENT APPLICATIONS AND SEQUENCE STRATEGIES - A REVIEW

In this article the relation between contrast medium (CM) application and sequence parameters will be discussed with respect to clinical use of the contrast-enhanced magnetic resonance angiography (CE-MRA) in t he peripheral vessel region. The adjustment of the sequence parameters , the CM application timing and the bolus geometry is necessary for an effective use of CE-MRA. Investigation protocols for several vascular regions differ mainly corresponding to varying fields of view and sla b thickness. Restrictions of increasing the measurement time are expec ted in peripherally localized vessels if fast arteriovenous transit ti me occurs, The vessel contrast depends from (1) optimal CM bolus timin g and (2) bolus geometry defined by the parameters of the intravenous bolus injection (flow rate, dose and NaCl hush volume), Our study resu lts have shown that the bolus remains compact but also shorter if a hi gher how rate is being applied at equal dose. The enlargement of the N aCl hush volume has evidently caused an increased intraarterial CM con centration and a slightly bolus lengthening, The exact timing regimen requires an automated mechanical CM injection pump. In most countries, a total dose of 0.3 mmol/kg Gd is allowed for application during one investigation. Therefore, obtaining an angiogram of the entire iliac a nd leg region this total dose must be separated, 0.1 mmol/kg for each of the three measurements can be recommended. Otherwise, using this lo wer CM dose results in less spatial resolution. At least a dosage of 0 .2 mmol/kg Gd is necessary to achieve a higher spatial resolution, The calculation of CM dosage should be also related to the dedicated vess el region of interest than to the body weight only.