To compare test bolus and bolus-tracking techniques for intravenous contrast material administration at 16-detector row computed tomographic (CT) coronary angiography.
This study had institutional review board approval, and patients gave informed consent. Thirty-eight patients (mean age, 60 years; three women) were randomized into two groups according to bolus timing technique: group 1 (20-mL test bolus with 100-mL main bolus) and group 2 (bolus tracking with 100-mL main bolus). All patients underwent electrocardiography-gated 16-detector row CT coronary angiography with 12 detectors (collimation, 0.75 mm; rotation time, 420 msec). In group 1, test bolus peak attenuation was used as a delay, while in group 2, a +100-HU threshold in ascending aorta triggered angiographic acquisition, with an additional 4-second delay for patient instruction. Attenuation was measured in the longitudinal direction throughout the examination in three main vessels: ascending aorta (region of interest [ROI] 1), descending aorta (ROI 2), and main pulmonary artery (ROI 3). Mean attenuation and slope of bolus geometry curve were calculated in each patient and ROI. Attenuation at origin of coronary arteries was measured. Student t test was used to compare results.
Mean scan delay was 6 seconds longer in group 2 (P < .05). Average attenuation values were 306.6 HU +/- 44.0 (standard deviation) and 328.2 HU +/- 58.6 (P > .05) in ROI 1, 291.6 HU +/- 45.1 and 326.4 HU +/- 62.6 (P > .05) in ROI 2, and 354.7 HU +/- 78.0 and 305.3 HU +/- 71.4 (P < .05) in ROI 3 for groups 1 and 2, respectively. Average slope values were 5.8 and -0.8 (P < .05) in ROI 1, 7.7 and 0.7 (P < .05) in ROI 2, and -1.0 and -13.3 (P < .05) in ROI 3 for groups 1 and 2, respectively. Average attenuation values in left main, left anterior descending, and left circumflex arteries were higher in group 2 (P < .05); there were no differences (P > .05) between groups in right coronary artery.
Bolus-tracking yields more homogeneous enhancement than does the test bolus technique.
"Cademartiri et al. suggested that the bolus tracking technique yields more homogeneous enhancement than does the test bolus technique. Others, however, have found that with the use of appropriate timing, test bolus technique can yield similar results to bolus tracking. "
[Show abstract][Hide abstract] ABSTRACT: Multidetector computed tomography angiography (MDCTA) has become a well-established modality for limb angiography for a variety of indications. The technique of MDCTA depends on the scanner features including the number of detector rows, rotation speeds and single or dual source energy. Integral to a diagnostic quality CTA is the acquisition timing. Various techniques are available for determining the appropriate timing of scan acquisition which includes fixed delay, test bolus and the bolus tracking technique. The transit times of contrast from the aorta to the peripheral arteries shows a wide variability and is dependent upon the inter individual hemodynamic states. The bolus tracking technique is the most preferred one which allows reliable scan timing with acceptable contrast volume and radiation dose. Pitfalls with all these techniques are well described and we report one such technical pitfall in a case of left foot arteriovenous malformation (AVM) where the bolus tracking technique employed for scan triggering failed to initiate acquisition.
Indian Journal of Radiology and Imaging 05/2014; 24(2):125. DOI:10.4103/0971‑3026.134387
"The 40-mL group was found to have a lower mean venous attenuation and less residual CM in IJV on the ipsilateral side of injection than those of 50-mL group. Moreover, we attempted to decrease the amount of CM used for the test bolus to 5 mL, based on the faster rate of injection of 6 mL/s, which was significantly lower than those we found in the literature [14,31,15,32,33]. In our study, the average PME of a 5-mL test bolus was 176 HU at the bifurcation of the CCA. "
[Show abstract][Hide abstract] ABSTRACT: Our study aims to evaluate the image quality and feasibility of 128-slice dual-energy CTA (DE-CTA) for supra-aortic arteries using reduced amounts of contrast medium (CM).
A prospective study was performed in 54 patients receiving CTA of the head and neck with a 128-slice dual-source CT system. Patients were randomized into two groups with a volume of either 40 mL of CM (Group I) or 50 mL of CM (Group II). Arterial and venous enhancements were recorded for quantitative assessment. Qualitative assessments for images without bone removal (BR) were based on a) the visualization of the circle of Willis and b) streak artifacts due to residual CM in the subclavian or internal jugular veins ipsilateral to injection of CM. Qualitative assessment of dual-energy images using BR was based on the presence of bone remnants and vessel integrity. Quantitative data was compared using the Student t test. The χ(2) test was used for the qualitative measurements of streak artifacts in veins while the Mann-Whitney U test was used for the qualitative measurements of images with BR.
Arterial and venous attenuation was significantly higher in Group II (P=0.000). Image quality regarding the circle of Willis was excellent in both groups (3.90±0.30 for Group I and 4.00±0 for Group II) . Imaging of the internal jugular veins was scored higher in Group I (1.87±0.72) compared with Group II (1.48±0.51) (P=0.021). Within Group I using BR, mean scores for bone remnants did not differ significantly (P>0.05) but mean scores of vessel integrity (P<0.05) did.
Contrast-enhanced head and neck CTA is feasible using a scan protocol with low amounts of contrast medium (40 mL) on a 128-slice dual-energy CTA. The 40-mL protocol provides satisfactory image quality before and after dual-energy bone-removal post-processing.
PLoS ONE 11/2013; 8(11):e80939. DOI:10.1371/journal.pone.0080939 · 3.23 Impact Factor
"Johnson et al.7 also found no significant difference between the two different timing techniques, although the results were in relation to ECG-gated CT angiography of the chest. Cademartiri et al.8 compared contrast enhancement using both a bolus tracking and a test bolus protocol on a 16-slice multi-detector CT (MDCT) in coronary angiography. They concluded that bolus tracking yielded a more homogenous enhancement, although mean enhancement was higher for the test bolus group (354.7 ± 78 HU) than when bolus tracking was used (305.3 ± 71.4 HU). "
[Show abstract][Hide abstract] ABSTRACT: Introduction
Optimal arterial opacification is crucial in imaging the pulmonary arteries using CT. This poses the challenge of precisely timing data acquisition to coincide with the transit of the contrast bolus through the pulmonary vasculature. The aim of this study was to investigate if a change in CT pulmonary angiogram (CTPA) scanning protocol resulted in improved opacification of the pulmonary arteries. Comparison was made between the Smart Prep Protocol (SPP) and the Timing Bolus Protocol (TBP) for opacification in the pulmonary trunk.
A total of 160 CTPA examinations (80 using each protocol) performed between January 2010 and February 2011 were assessed retrospectively. Region of interest (ROI) measurements were taken and the average pixel value, standard deviation, maximum and minimum were recorded. For each of these variables a mean value was then calculated and compared for each protocol.
Minimum opacification of 200 HU was achieved in 98% of the TBP sample but only 90% the SPP sample (p = 0.0983). The average ROI measurement over the pulmonary trunk for the SPP was 329 ( 21) HU, while for the TBP it was 396 ( 22) HU (p = 0.0017). The TBP also recorded higher maximum (p = 0.0024) and minimum (p = 0.0039) levels of opacification.
Although results differ from previous studies, this study has found that a TBP resulted in significantly better opacification of the pulmonary trunk than the SPP.
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