CT Image Quality for CT Pulmonary Embolism (CT PE) and Chest CT Aorta Acquired with Power Injection via an Arm Port Ryan Verity 1, David Leswick 2 MD FRCPC, Brent Burbridge 2 MD FRCPC, Rhonda Bryce 3 MD, Hyun Lim PhD 3 1 – College of Medicine, University of Saskatchewan 2 – Medical Imaging, College of Medicine, University of Saskatchewan 3 – Clinical Research Support Unit, College of Medicine, University of Saskatchewan

Disclosures  No conflicts of interests to declare

Acknowledgements  We offer many thanks to the following groups/people: Our statistical support team, Dr. Bryce & Dr. Lim U of S Medical Students Hager Haggag and Christine Roh, for their help in designing the data collection form The local CT technologists for their technical support with the software analysis and data collection  I would like to thank Dr. Leswick & Dr. Burbridge for their support, guidance and mentorship with this project

Introduction  Haggag et al. 1 investigated CT image quality of mixed phase chest CT scans acquired with power injection via an arm port.  Image quality in the chest CT was equivalent between injection via port line versus injection via peripheral iv.  During this phase of enhancement, contrast had already cleared from brachiocephalic vessels and SVC.  Therefore, it was proposed that when imaging sooner after injection, port line injection may result in improved image quality compared to IV injection. 1) Haggag, H., Roh, C., Chan, I. Y., Burbridge, B., & Leswick, D. (2015). Quality of Computed Tomography Images Acquired With Power Injection of an Arm Port. Canadian Association of Radiologists Journal.

Hypothesis  Our objective was to determine if image quality of CT pulmonary embolism (CT PE) and aortic phase (CT Ao) studies would differ between injection of contrast via an arm port versus a peripheral arm intravenous (IV).  We hypothesized that injection via arm ports would produce better quality images because of decreased streak artifact from highly concentrated iodinated contrast in the brachiocephalic veins and SVC during traditional IV injection.

Methods  Retrospective review of 105 patients who had a power injectable, totally implanted, arm port (TIVAD) at our facility between December 2013 and June  The power injectable port used was the Angiodynamics, Smart Port ® CT Mini (Angiodynamics, Queensbury, NY, USA).  Inclusion criteria were all CT PE and Ao studies at any site in the province with contrast injection via the power injectable arm ports and thin (1.00 mm) axial standard algorithm images available for image analysis.  6 patients (3 PE, 3 Ao) were identified, as were 6 control subjects.  Image quality was assessed on General Electric Advantage Workstation software, version 4.1 (GE Healthcare, Chicago, USA).

Methods: Objective Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were calculated 2 : SNR structure = SI structure /BN CNR structure = (SI structure -SI muscle )/BN 4 sites were assessed for PE studies: main pulmonary artery (MPA), right pulmonary artery (RPA), right upper lobe pulmonary artery (RUL), and left lower lobe pulmonary artery (LLL). 2 sites were assessed for Ao studies: aortic arch and ascending Aorta (AA). 2) Heyer, C. M., Mohr, P. S., Lemburg, S. P., Peters, S. A., & Nicolas, V. (2007). Image quality and radiation exposure at pulmonary CT angiography with 100-or 120-kvp protocol: prospective randomized study 1. Radiology, 245(2),

Methods: Objective Regions of interest (ROI) used for objective assessment were positioned to include adequate cross-sectional area within structures (SI) and air (BN).

Methods: Subjective  Assessment was based on the following 3 factors, with each factor receiving a score of 1-4.  A score of 1 or 2 was considered inadequate, and a score of 3 or 4 was considered adequate Contrast OpacificationStreak (Regional) ArtifactDiagnostic Confidence 1Non-Diagnostic 2Poor 3Moderate 4Good (Well opacified)Good (No artifact)Excellent

Results Representative images acquired from both the arm port and peripheral iv injections.

Results: Objective Injection via arm port produces similar or improved mean SNR and CNR values for sites of assessment.

Results: Subjective Number of adequate assessment points (N=18) in both the arm port and the peripheral IV group.

Results: Subjective  Percentage of adequate scores (3 or 4): Contrast Opacificaiton: 78% Port versus 55% IV Streak Artifact: 78% Port versus 55% IV Diagnostic Confidence: 72% Port versus 55% IV  On subjective assessment, all port scores were higher or equal to IV scores.

Discussions & Limitations  This was a exploratory study to investigate image quality of contrast injection via a modified technique.  Injection via arm ports appear to generate similar or higher quality images on both subjective and objective assessment of both CT PE and Aortic phase imaging of the chest.  Limited sample size complicated statistical analysis. Limited sample size because relatively few patients have these power injectable port lines, with CT PE and aorta exams relatively uncommon in this population. Sample size further limited by only assessing studies with thin images archived on PACS.

Conclusions This exploratory study promotes further investigation of power injection via totally implanted devices for when they should be utilized for imaging studies. If a patient has a power injectable port in place, it is reasonable to use it for the injection of contrast for CT PE and CT Ao studies.