Article

Dual-energy CT angiography of the lungs: comparison of test bolus and bolus tracking techniques for the determination of scan delay.

Department of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, D-68167 Mannheim, Germany.
European journal of radiology (Impact Factor: 2.65). 01/2012; 81(1):132-8. DOI: 10.1016/j.ejrad.2010.06.023
Source: PubMed

ABSTRACT To prospectively compare test bolus and bolus tracking for the determination of scan delay of pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism.
60 consecutive patients referred for CTA for exclusion of PE were randomized either into a test bolus group or into a bolus tracking group. All exams were performed on a 64-channel dual source CT scanner. A standard single-acquisition dual-energy CTA was performed after injection of 100ml Iomeprol 400 followed by a saline chaser of 4 ml/s. The scan delay was determined using either test bolus (n=30) or bolus tracking (n=30). Test bolus was performed using an additional 20 ml Iomeprol 400 injected with a rate of 4 ml/s during acquisition of a series of dynamic low-dose monitoring scans followed by injection of a saline bolus of 20 ml using the same flow rate. For DECT angiography of the lungs 100ml Iomeprol 400 was injected with an injection rate of 4 ml/s followed by a saline chaser of 20 ml using the same flow rate. Attenuation profiles of different vascular segments (pulmonary arteries, pulmonary parenchyma, aorta, all 4 heart chambers) were measured to evaluate the timing techniques. Overall image quality of dual-energy "perfusion" maps and virtual 120 kV CTA images was evaluated by two radiologists regarding the present of artifacts.
In all patients an adequate and homogeneous contrast enhancement of more than 400 Hounsfield units (HU) was achieved in the different vascular districts. No statistically significant difference between test bolus and bolus tracking was found regarding vessel attenuation or overall image quality.
A homogeneous opacification of the different vascular territories and the pulmonary parenchyma as well as a sufficient image quality can be achieved with either bolus tracking or test bolus techniques.

0 Bookmarks
 · 
366 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the feasibility of dual-energy computed tomography (DECT) in differentiating malignant from benign mediastinal tumors. We prospectively enrolled 25 patients (14 males; mean age: 56.7 years) who had suspected mediastinal tumors on chest radiography or non-contrast chest computed tomography (CT). All patients underwent a two-phase DECT using gemstone spectral imaging (GSI) mode (GE HD750). For the quantitative analysis, two investigators measured the following parameters of the tumors in the early and the delayed phases: CT attenuation value in Hounsfield units (HU) and iodine concentration (mg/ml). Pathological results were used for a final diagnosis. Statistical analyses were performed using the Fisher's exact test and the Mann-Whitney t-test. 10 patients (40%) had benign pathology, while 15 (60%) had malignant pathology. The iodine concentration measurements were significantly different between benign and malignant tumors both in the early phase (1.38mg/ml vs. 2.41mg/ml, p=0.001) and in the delayed phase (1.52mg/ml vs. 2.84mg/ml, p=0.001), while mean attenuation values were not significantly different in both phases (57.8HU vs. 69.1HU, p=0.067 and 67.4HU vs. 78.4HU, p=0.086, respectively). Dual-energy CT using a quantitative analytic methodology can be used to differentiate between benign and malignant mediastinal tumors.
    European journal of radiology 06/2013; · 2.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: RATIONALE AND OBJECTIVES: To prospectively compare four contrast material injection protocols for dual-energy computed tomography (CT) pulmonary angiography (DE-CTPA) in patients with suspected pulmonary embolism (PE). MATERIALS AND METHODS: One hundred twenty consecutive patients were randomized to contrast material injection protocols defined by different iodine concentrations and iodine delivery rates (IDRs): (A) 80 mL iopromide 370/4 mL/sec = IDR 1.4 gI/sec; (B) 80 mL iopromide 370 at 3 mL/sec = IDR 1.1 gI/sec; (C) 98 mL iopromide 300 at 4.9 mL/sec = IDR 1.4 gI/sec; and (D) 98 mL iopromide 300 at 3.7 mL/sec = IDR 1.1 gI/sec. Attenuation values were measured in the inflow tract (subclavian vein-superior vena cava-right atrium), target tract (right ventricle-pulmonary trunk-pulmonary arteries), and outflow tract (left atrium-left ventricle-ascending aorta). Two readers assessed subjective image quality of CTPA images and iodine perfusion maps. The number of artifacts due to hyperdense contrast material on iodine perfusion maps was recorded. RESULTS: Target tract attenuation was highest for protocol A with 374 ± 98 Hounsfield units (HU) (highly concentrated contrast material/high IDR). This was significant compared to protocols B and D (P = .0118, P = .0427) but not compared to protocol C (P = .3395). No significant difference in target tract attenuation was found between protocols B (309 ± 80 HU), protocol C (352 ± 119 HU), and D (325 ± 74 HU). CTPA and iodine perfusion map image quality for protocol A was rated significantly higher compared to all other protocols (median score = 5/4; P < .0001 for both) with moderate interreader agreement (κ = 0.58/0.47). Protocols A and B displayed increased artifacts on iodine perfusion maps compared to protocols C and D (3 versus 2). CONCLUSION: Despite increased artifacts on iodine perfusion maps, highly concentrated iodinated contrast material combined with high flow rates provides improved diagnostic image quality and has the highest target-tract attenuation for DE-CTPA protocols.
    Academic radiology 06/2013; · 2.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to assess the effectiveness of the modified test-bolus (mTB) method in computed tomography pulmonary angiography (CTPA). The Institutional Review Board approved this retrospective study. We reviewed 24 patients (nine men, 15 women; age range, 21-88 years) in whom CTPA was performed either by Bolus-Tracking (BT) (n = 12) or mTB (n = 12) methods. Pulmonary transit time (PTT) was used to determine scan delay time and contrast volume in the mTB group. The contrast volume, radiation dose, quantitative measures, and qualitative scores of enhancement were compared. The chi-squared test, Mann-Whitney U test, and κ statistics were used. The significance level was 0.05. The effective dose (P = 0.028) and contrast volume (P < 0.001) was significantly lower in the mTB group than those in the BT group. The difference in the quantitative measures and qualitative scores of enhancement between groups was statistically insignificant (P = 0.729, P = 0.635, respectively). Significantly fewer artefacts were observed in the mTB group (P = 0.024). By taking into account PTT, mTB appears to be a promising method for tailoring CTPA to the patient with the use of less contrast material and resulting in fewer artifacts.
    Japanese journal of radiology 01/2014; · 0.73 Impact Factor

Full-text

View
174 Downloads
Available from
May 20, 2014