Non-Enhanced 3D MR Angiography of the Lower Extremity using ECG-Gated TSE Imaging with Non-Selective Refocusing Pulses – Initial Experience

Zusammenfassung

Ziel: Im Rahmen dieser Studie sollte eine kontrastmittelfreie 3-D-Turbo-Spin-Echo(TSE)-MR-Angiografie mit nicht selektiven Refokussierungspulsen (NATIVE SPACE MRA) zur Darstellung der Becken- und Beinarterien evaluiert werden. Material und Methoden: Bei 8 gesunden Probanden und 3 Patienten mit peripherer arterieller Verschlusskrankheit (pAVK) wurde eine 3-Etagen-Bildgebung (Becken-, Oberschenkel- und Unterschenkelarterien) an einem 1,5 T MRT durchgeführt. Bei allen gesunden Probanden wurden 4 Untersuchungsprotokolle mit folgenden Parametern angefertigt: S 1: Bildakquisition mit jedem Herzschlag (RR = 1), Spoiler-Gradient von 25 % (SG = 25 %); S 2: RR = 1, SG = 0 %; S 3: RR = 2, SG = 25 % S 4: RR = 2, SG = 0 %. Die subjektive Bildqualität (4-Punkte-Skala; 4 = exzellent, 1 = nicht diagnostisch) und das relative SNR wurden ermittelt. Zudem wurde das Ausmaß der mittels SPACE MRA dargestellten Stenosen bei 3 pAVK-Patienten evaluiert. Ergebnisse: Die mittlere subjektive Bildqualität der Beckenarterien wurde für alle Untersuchungsprotokolle signifikant schlechter als für die Ober- und Unterschenkelarterien bewertet (p < 0,0001). Für die Beckenarterien war die subjektive Bildqualität für das Protokoll S 1 signifikant schlechter als für S 3 und S 4 (p < 0,01). Hingegen war für die Ober- und Unterschenkelarterien die subjektive Bildqualität für Protokoll S 2 signifikant schlechter als für S 3 und S 4 (p < 0,01). Die relative SNR war für die Protokolle S 3 und S 4 für alle Regionen signifikant höher als für S 1 und S 2 (p < 0,0001). Mittels SPACE MRA konnten bei 3 pAVK-Patienten 7 signifikante Stenosen dargestellt werden. Schlussfolgerung: Die EKG-getriggerte SPACE MRA ist eine vielversprechende Untersuchungstechnik zur kontrastmittelfreien Darstellung der Becken- und Beinarterien.

Abstract

Purpose: To evaluate non-enhanced 3D MR angiography using turbo spin echo (TSE) imaging with non-selective refocusing pulses (NATIVE SPACE MRA) for the visualization of the arteries of the lower extremity. Materials and Methods: Three-station imaging (iliac arteries, femoral arteries, arteries of the lower leg) was performed in 8 healthy volunteers and 3 patients with peripheral artery disease (PAD) using a 1.5 T MR scanner. In 8 healthy volunteers, 4 different acquisition schemes were performed with the following imaging parameters: S 1: acquisition with every heartbeat (RR = 1), spoiler gradient of 25 % (SG = 25 %); S 2: RR = 1, SG = 0 %; S 3: RR = 2, SG = 25 %; S 4: RR = 2, SG = 0 %. The subjective image quality on a 4-point-scale (4 = excellent to 1 = not diagnostic) and relative SNR were assessed. In 3 patients with peripheral artery disease (PAD), SPACE MRA was performed for assessment of stenosis. Results: The mean subjective image quality was significantly lower for the iliac arteries compared to the femoral arteries and arteries of the lower leg (p < 0.0001). The subjective image quality for acquisition scheme S 1 was significantly lower than the image quality for S 3 and S 4 for the iliac arteries (p < 0.01), while the subjective image quality for acquisition scheme S 2 was significantly lower than S 3 and S 4 for the femoral arteries and the arteries of the lower leg (p < 0.01). The relative SNR was significantly higher for acquisition schemes S 3 and S 4 as compared to S 1 and S 2 (p < 0.0001) for all regions. SPACE MRA disclosed 7 significant stenoses in 3 PAD patients. Conclusion: ECG-gated SPACE MRA is a promising imaging technique for non-enhanced assessment of the arteries of the lower extremity.

Key words

arteries - extremities - pelvis - MR-angiography

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