Comparison of a Standard and a High-Concentration Contrast Medium Protocol for MDCT Angiography of the Lower Limb Arteries

Abstract

Purpose: To prospectively compare a compact bolus (CB) injection protocol using high-iodine concentration contrast medium with a standard bolus (SB) injection protocol at equi-iodine doses for run-off computed tomographic angiography (CTA).

Materials and Methods: 64 patients with suspected peripheral arterial disease who underwent 40 or 64-slice run-off CTA were included in this IRB-approved study. Patients were randomized to undergo the CB protocol (32 patients, iomeprol 400mgI/mL, 100 mL, 4 mL/sec) or the SB protocol (32 patients, iomeprol 300mgI/mL, 134 mL, 4 mL/sec). Luminal contrast density (CD) values were measured and arterial opacification (AO) was scored (5-point scale). Cases of venous overlay or bolus overriding were documented.

Results: Overall arterial CD was significantly higher with the compact bolus (CB: 279 ± 57HU, SB: 234 ± 32HU, p = 0.0017). Segmental CD was significantly higher (p< 0.05) in 7 of 16 evaluated segments. Patency-based comparison revealed superior AO in vessels with relevant (50 – 99 %) stenoses (CB: 4.54 vs. SB: 4.18, p = 0.04). Contrast bolus overriding without pathological reasons, i. e., acute occlusions, was noted in one patient in each group. Venous overlay was observed less frequently in the CB group (CB vs. SB: 12 vs. 19 patients, n. s.; 29 of 64 legs [45 %] vs. 44 of 64 legs [69 %], p = 0.01).

Conclusion: At equi-iodine doses, the CB protocol led to a quantitatively and qualitatively higher arterial opacification compared to the SB protocol. Therefore, a CB protocol should be favored for run-off CTA.

Zusammenfassung

Ziel: Zielsetzung war der prospektive Vergleich eines Kompaktbolus(CB)-Injektionsprotokolls unter Verwendung eines Kontrastmittels mit hoher Jodkonzentration mit einem Standardbolus(SB)-Injektionsprotokoll bei konstanter Gesamtjoddosis bei der CT-Angiografie der Becken- und Bein-Arterien.

Material und Methoden: In die Studie wurden 64 Patienten eingeschlossen, die eine 40- oder 64-Zeilen-CT-Angiografie der Becken- und Bein-Arterien bei Verdacht auf Vorliegen einer peripheren arteriellen Verschlusskrankheit erhielten. Die Patienten wurden auf 2 Gruppen randomisiert und entweder mit Protokoll CB (32 Patienten, Iomeprol 400 mg Jod/ml, 100 ml, 4 ml/s) oder dem Protokoll SB (32 Patienten, Iomeprol 300 mg Jod/ml, 134 ml, 4 ml/s) untersucht. Die luminale Kontrastdichte (CD) wurde gemessen und das arterielle Enhancement (AO) auf einer 5-Punkte-Skala bewertet. Venöse Überlagerungen und ein Überholen des Kontrastmittelbolus wurden dokumentiert.

Ergebnisse: Die gemittelte arterielle CD war unter Verwendung des CB Protokolls signifikant höher (CB:279 ± 57HE, SB: 234 ± 32HE, p = 0,0017). In 7 von 16 arteriellen Segmenten war die arterielle CD ebenfalls signifikant höher (p < 0,05), darüber hinaus wurde in Gefäßen mit hämodynamisch relevanten Stenosen (Stenosegrad 50 – 99 %) das arterielle Enhancement (AO) unter Verwendung des CB Protokolls im Mittel besser bewertet (CB: 4,54 vs. SB: 4,18, p = 0,04). Ein Überholen des Kontrastmittelbolus ohne Vorliegen eines pathologischen Grundes (z. B. akuter Verschluss) wurde bei je einem Patienten pro Gruppe beobachtet. Eine venöse Überlagerung trat in der CB-Gruppe seltener auf (CB vs. SB: 12 vs. 19 Patienten, n. s.; 29 von 64 Beinen [45 %] vs. 44 von 64 Beinen [69 %], p= 0,01).

Schlussfolgerung: Ein kompakter, hochdichter Kontrastmittelbolus (CB) führte im Vergleich zum Standardprotokoll (SB) bei gleicher Gesamtjoddosis zu einer quantitativ und qualitativ höheren Gefäßkontrastierung im Rahmen der CT-Angiografie der Becken- und Bein-Arterien und sollte daher vorzugsweise eingesetzt werden.

Key words

extremities - vascular - CT angiography

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