Carbon Dioxide-Contrasted Computed Tomography Angiography: High Pitch Protocols and Adapted Injection Parameters Improve Imaging Quality

T. Penzkofer; K. Slebocki; J. Grommes; P. Bruners; P. P. Isfort; N. Heussen; T. Schmitz-Rode; C. K. Kuhl; S. Langer; A. H. Mahnken

doi:10.1055/s-0032-1325603

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, Table of Contents

Rofo 2013; 185(2): 128-135
DOI: 10.1055/s-0032-1325603

Experimentielle Radiologie

Carbon Dioxide-Contrasted Computed Tomography Angiography: High Pitch Protocols and Adapted Injection Parameters Improve Imaging Quality

Kohlendioxid-kontrastierte computertomografische Angiografie: Protokolle mit hohem Pitch und angepassten Injektionsparametern verbessern die Bildqualität

Authors

T. Penzkofer

¹Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, Germany

²Surgical Planning Laboratory, Department of Radiology, Brigham and Women‘s Hospital, Harvard Medical School, Boston, USA

³Applied Medical Engineering, Helmholtz-Institute Aachen, RWTH Aachen University Hospital, Aachen, Germany
K. Slebocki

¹Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, Germany
J. Grommes

⁴European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, RWTH Aachen University Hospital, Aachen, Germany

⁵Department of Surgery, Maastricht University Medical Center, Maastricht, The Netherlands
P. Bruners

¹Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, Germany

³Applied Medical Engineering, Helmholtz-Institute Aachen, RWTH Aachen University Hospital, Aachen, Germany
P. P. Isfort

¹Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, Germany

³Applied Medical Engineering, Helmholtz-Institute Aachen, RWTH Aachen University Hospital, Aachen, Germany
N. Heussen

⁶Department of Medical Statistics, Medical Faculty, RWTH Aachen University, Aachen, Germany
T. Schmitz-Rode

³Applied Medical Engineering, Helmholtz-Institute Aachen, RWTH Aachen University Hospital, Aachen, Germany
C. K. Kuhl

¹Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, Germany
S. Langer

⁴European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, RWTH Aachen University Hospital, Aachen, Germany

⁵Department of Surgery, Maastricht University Medical Center, Maastricht, The Netherlands
A. H. Mahnken

¹Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Aachen, Germany

³Applied Medical Engineering, Helmholtz-Institute Aachen, RWTH Aachen University Hospital, Aachen, Germany

Abstract

Purpose: To systematically investigate the impact of image acquisition and contrast injection parameters for CO₂-enhanced CT angiography (CTA) of the aorto-iliac and peripheral arteries in a pig model using commercially available equipment. The aim was to establish an imaging protocol that is ready for use in human subjects.

Materials and Methods: Three domestic swine underwent CO₂-CTA with varying injection parameters: pitch (1.0, 3.0), injection pressure (0.7 bar, 1.0 bar, 1.3 bar) and scan delay (2 s, 4 s, 6 s). Objective (vessel diameter) and subjective (image quality) parameters and applied radiation doses were systematically evaluated. To ensure clinical applicability of the setting, only approved catheters/injectors and standard injection parameters were evaluated.

Results: The image quality scores were superior and the vessel diameter was larger with high pitch in comparison to standard pitch (diameters: 4.7 ± 2.0 mm vs. 3.6 ± 2.1 mm, p = 0.0040, scores: 2.6 ± 1.1 vs. 2.0 ± 1.1, p = 0.0038). High injection pressure (1.3 bar) improved the image quality as assessed by subjective and objective ratings (diameters: 3.6 ± 2.0 mm, 4.0 ± 2.1 mm and 4.6 ± 2.1 mm, for 0.7, 1.0 and 1.3 bar, p-values ≤ 0.0052, scores: 1.9 ± 1.1, 2.3 ± 1.1 and 2.7 ± 1.2, p-values ≤ 0.0017), the same was observed for a shorter injection delay (diameters: 3.5 ± 2.0 mm, 4.2 ± 2.1 mm and 4.8 ± 2.1 mm, for 6 s, 4 s, and 2 s, p ≤ 0.0022, scores: 1.9 ± 1.1, 2.3 ± 1.1 and 2.7 ± 1.1, p-values ≤ 0.0013). The dose length products were 239 ± 47 mGycm (high pitch) and 565 ± 63 mGycm (standard pitch, p-values < 0.0001).

Conclusion: A higher pitch, shorter delay and higher injection pressure improve image quality in CO₂-enhanced CTA. Since commercially available, clinically approved equipment was used. The protocol is now ready for use in human subjects.

Zusammenfassung

Ziel: Es sollen in einem klinisch zugelassenen Aufbau der Einfluss der Bildgebungs- und Injektionsparameter auf die computertomografische (CT) Kohlendioxid(CO₂)-kontrastierte Becken-Bein-Angiografie (CO₂-CTA) im Tiermodell untersucht werden. Ziel ist, ein Bildgebungsprotokoll zu etablieren, das für den Einsatz im Menschen geeignet ist.

Material und Methoden: In 3 Hausschweinen wurden CO₂-CTAs durchgeführt, wobei der Pitch (1,0, 3,0), der Injektionsdruck (0,7 bar, 1,0 bar, 1,3 bar) und die Scanverzögerung (2 s, 4 s, 6 s) systematisch variiert wurden. Objektive (Gefäßdurchmesser) und subjektive (Bildqualität) Kriterien sowie die applizierte Strahlendosis wurden evaluiert. Um eine klinische Einsetzbarkeit der entwickelten Protokolle zu gewährleisten, wurden nur zugelassene Interventionsmaterialien und Injektionsparameter untersucht.

Ergebnisse: Die Bildqualität war besser und die Gefäßdurchmesser größer, wenn Untersuchungsprotokolle mit hohem Pitch verwendet wurden (Durchmesser: 4,7 ± 2,0 mm gegenüber 3,6 ± 2,1 mm, p = 0,0040, Bildqualität (Skala von 1 – 4): 2,6 ± 1,1 vs. 2,0 ± 1,1, p = 0,0038). Höherer Injektionsdruck (1,3 bar) verbesserte ebenfalls die subjektiven und objektiven Bewertungsparameter (Gefäßdurchmesser: 3,6 ± 2,0 mm, 4,0 ± 2,1 mm und 4,6 ± 2,1 mm, jeweils für 0,7, 1,0 und 1,3 bar, p-Werte ≤ 0,0052, Bildqualität: 1,9 ± 1,1, 2,3 ± 1,1 und 2,7 ± 1,2, p-Werte ≤ 0,0017), ähnliches war für eine kürzere Scanverzögerung feststellbar (Durchmesser: 3,5 ± 2,0 mm, 4,2 ± 2,1 mm und 4,8 ± 2,1 mm, für 6 s, 4 s, und 2 s, p ≤ 0,0022, Bildqualität: 1,9 ± 1,1, 2,3 ± 1,1 und 2,7 ± 1,1, p-Werte ≤ 0,0013).

Schlussfolgerung: Höherer Pitch, kürzere Scanverzögerung und höherer Injektionsdruck verbessern die Bildqualität in der CO₂-CTA. Durch die Verwendung von zugelassenen Materialien ist das vorliegende Protokoll nun auf den Menschen übertragbar.

Key words

CT angiography - interventional procedures - vascular - experimental

Full Text

References

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