CT angiography quality is affected by many factors related to temporal, spatial, and contrast resolution. Contrast resolution is affected by the quality of contrast enhancement, which relates to the iodine delivery rate and scan timing. Iodine delivery rate can be increased by using higher concentration contrast agents or higher infusion rates. Multiple studies have shown that the contrast infusion rate directly affects the arterial enhancement level and image quality [7, 8]. Not all patients can tolerate high-contrast infusion rates, however, owing to the quality of their venous access. Accordingly, IV catheter selection and the IV contrast infusion rate are tailored to the individual patient’s vein quality [9, 10].
In our study, we are focus on proper IV catheter selection during CCTA as in our experience it is important for patients and image quality with few types of research in this subject. One of the basic components of good venous access is the IV catheter. CCTA requires good peripheral venous access which in turn depends on a good-sized vein and large bore IV catheter to allow a high flow of contrast and the saline chaser. Regularly, a 18 g IV catheter is used to allow infusion of contrast at ≥ 5 mL/s. A right antecubital vein is preferred access to avoid streak artifacts that may affect image quality if a left vein is used [3, 11, 12].
A new peripheral IV catheter ( BD-Nexiva closed IV catheter) is intended for use with a power injection system. One important goal of the design was to create a small (22 G and 24 G) peripheral IV catheter device capable of safely delivering power injection flow rates. The catheter system has increased pressure capability in addition to diffuser holes in the catheter tip which improves catheter stability and decreases tip jet velocity compared to a standard IV catheter. Furthermore, the diffuser holes reduce system pressure at the tip of the catheter during open-flow conditions [13, 14].
In our study we found that successful catheter placement on the first attempt was 51/54 patients at the first trial and 3/54 after 2nd trial for 22-gauge fenestrated catheter however no cases from the first trial, 25/54 after 2nd trial and 29/54 after 3rd trial for 18-gauge non-fenestrated catheter. Also, no cases of contrast extravasation with 22-gauge fenestrated catheter however 23 cases with an 18-gauge non-fenestrated catheter and these agree with Johnson et al. [9] that also provides evidence that the presence of fenestrations reduces the risk of venous rupture and extravasation by directing flow from a single end hole to across multiple side holes and the end hole, thus enabling a higher contrast infusion rate.
In our study, mean vascular attenuations of the left main coronary artery, LV cavity, and descending aorta were higher in the 22-gauge fenestrated than in the 18-gauge non-fenestrated catheter (Fig. 3). In our study, mean vascular attenuations of the ascending aorta were not different. This finding can be explained by the use of bolus tracking for cardiac MDCT and fenestrated catheter. We used ascending aorta for bolus tracking method and short scan delay. Therefore, mean vascular attenuation of the ascending aorta was not statistically different despite the shorter time to peak enhancement in the fenestrated catheter and all this agrees with Kim et al. [15].
A number of studies have shown that the contrast infusion rate directly affects the arterial enhancement level and image quality for vascular imaging [16,17,18]. Therefore, we speculate that a fenestrated catheter will be a useful method for cardiac MDCT especially in patients with poor quality of venous access.
Our study has a limitation that it was a retrospective study with a small sample size; however, our patient group size is still considerable because there are few investigations comparing fenestrated and non-fenestrated peripheral venous catheters for CCTA.
In this study, we report our experience of the closed IV catheter during CCTA regarding, mean vascular attenuation as well as patient’s feedback. The small diameter 22-gauge fenestrated catheter which allows an injection rate of > 6 m/s is the most cheerful advantage perceived by the patients. Mean vascular attenuations were higher and in this small size made puncture less painful, reduced the trials of insertion (usually single, rarely twice trials), easier, faster insertion, and almost complication-free, e.g., perforation, contrast extravasation or contamination and this agree with Tamura et al. [19].