Optimization of image quality in pulmonary CT angiography with low dose of contrast material (original) (raw)
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Minimizing contrast media dose in CT pulmonary angiography with high-pitch technique
The British Journal of Radiology, 2020
Objectives: To perform CT pulmonary angiography (CTPA) using a minimal amount of iodinated contrast media. Methods: 47 patients (25 females) with mean age 69 years (range 41–82 years) referred for contrast-enhanced chest CT were prospectively included in this Phase IV clinical drug trial. All participants underwent a study specific CTPA in addition to the chest CT. The participants received 80 mg I/kg body weight Iohexol contrast media using a preparatory saline bolus, a dual flow contrast/saline bolus and a saline flush, and a scanner protocol with 80 kVp dual source high-pitch mode. Three readers independently assessed the image quality on the 3-point scale non-diagnostic, adequate or good-excellent image quality. Additionally, the pulmonary arterial contrast opacification was measured. Results: On average, the patients received 16.8 ml Iohexol 350 mg I/mL (range 12–20 ml). Mean patient weight was 71 kg (range 50–85 kg). Identically for all readers, pulmonary embolism (PE) was det...
Japanese Journal of Radiology, 2014
The aim of this study was to assess the effectiveness of the modified test-bolus (mTB) method in computed tomography pulmonary angiography (CTPA). Materials and methods 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 j statistics were used. The significance level was 0.05. Results 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). Conclusion 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. Keywords CT-angiography Á Embolism/thrombosis Á Arteries Á Contrast agents Abbreviations BT Bolus-tracking CT Computed tomography CTDI Computed tomography dose index CTPA Computed tomography pulmonary angiography DLP Dose-length product ED Effective dose mTB Modified test-bolus PTT Pulmonary transit time ROI Region of interest t cont Contrast delivery time TCP aorta Time of contrast peak in the aorta TCP pulm Time of contrast peak in the pulmonary trunk t delay Scan delay time TB Test-bolus t scan Scanning time This study was presented as an electronic poster (LL-ERS-MO3A) at the meeting of the Radiological Society of North America (RSNA) in November 2012.
La radiologia medica
Objectives To retrospectively compare semi-qualitative and quantitative CT pulmonary angiography (CTPAs) image metrics testing diagnostic performance between protocols performed by 20 or 40 ml of contrast medium (CM) in patients with suspected pulmonary embolism (PE). Methods A total of 102 CTPAs performed by 20 ml (ultra-low volume: ULV) and 74 CTPAs performed by 40 ml (low volume: LV) protocol for the diagnosis of clinically suspected PE performed between October 2012 and September 2013 were retrieved. High-concentration CM (Iomeprol 400 mgI/ml) was injected at 3 ml/s (iodine delivery rate 1.2 mgI/s). Two radiologists (blinded and independent) semi-qualitatively scored vascular enhancement and image noise according to a fivepoint visual scoring system. Quantitative analysis was performed by regions of interest quantifying densitometric parameters, such as central and peripheral pulmonary arteries vascular contrast enhancement (CE, threshold for diagnostic CE ≥ 250 HU), and metrics for image noise. Continuous variables were compared by the Student's t test between groups if normally distributed while categorical variables were analyzed with the Chi-squared test. Interobserver agreement was calculated by the weighted kappa test; correlation coefficients were calculated using Pearson's correlation tests. Results The semi-qualitative scores for central and peripheral pulmonary arteries vascular CE were sufficient by ULV, yet inferior than LV (p < 0.001). Semi-qualitative image noise was comparable between ULV and LV, and the interobserver agreement was only fair for quality of peripheral vessels. Agreement on nondiagnostic semi-qualitative parameters was seen in 9/102 (8.8%) ULV CTPAs, in particular associated with massive PE (2/9), pleuro-pulmonary abnormalities (5/9) or without major abnormalities (2/9). Quantitative analysis showed that mean CE was lower in ULV group (p < 0.001), though greater than the diagnostic threshold of 250 HU in both groups. Conclusions Diagnostic vascular CE (> 250 HU) was obtained in both 20 ml and 40 ml CTPAs. CTPA by 20 ml of CM rendered diagnostic CE for the assessment of pulmonary arteries in patients with clinical suspicion of acute PE. Decreased image quality was mostly associated with massive PE or concomitant pleuro-parenchymal abnormalities.
Image Quality and Radiation Dose of Pulmonary CT Angiography Performed Using 100 and 120 kVp
American Journal of Roentgenology, 2012
P ulmonary CT angiography (CTA) performed with MDCT facilitates rapid and accurate diagnosis of pulmonary embolism (PE) [1]. The technique is widely accessible, is quick to perform, and has a high sensitivity (94-100%) and specificity (89-100%) for the diagnosis of acute PE [1, 2]. In addition, pulmonary CTA may show additional thoracic abnormalities in patients referred for exclusion of PE [1, 3]. Therefore, pulmonary CTA is widely accepted as the primary imaging modality for the investigation of patients with suspected PE. However, because PE is diagnosed in fewer than 10% of all pulmonary CTA examinations [1, 4, 5], there is increasing concern regarding the riskbenefit ratio for this examination particularly in younger patients and in women who are at higher risk of carcinogenesis from diagnostic
European Radiology
Objective To investigate the feasibility and image quality of high-pitch CT pulmonary angiography (CTPA) with reduced iodine volume in normal weight patients. Methods In total, 81 normal weight patients undergoing CTPA for suspected pulmonary arterial embolism were retrospectively included: 41 in high-pitch mode with 20 mL of contrast medium (CM); and 40 with normal pitch and 50 mL of CM. Subjective image quality was assessed and rated on a 3-point scale. For objective image quality, attenuation and noise values were measured in all pulmonary arteries from the trunk to segmental level. Contrast-to-noise ratio (CNR) was calculated. Radiation dose estimations were recorded. Results There were no statistically significant differences in patient and scan demographics between high-pitch and standard CTPA. Subjective image quality was rated good to excellent in over 90% of all exams with no significant group differences (p = 0.32). Median contrast opacification was lower in high-pitch CTP...
European Radiology, 2014
Objectives To find a threshold body weight (BW) below 100 kg above which computed tomography pulmonary angiography (CTPA) using reduced radiation and a reduced contrast material (CM) dose provides significantly impaired quality and diagnostic confidence compared with standard-dose CTPA. Methods In this prospectively randomised study of 501 patients with suspected pulmonary embolism and BW <100 kg, 246 were allocated into the low-dose group (80 kVp, 75 ml CM) and 255 into the normal-dose group (100 kVp, 100 ml CM). Contrast-to-noise ratio (CNR) in the pulmonary trunk was calculated. Two blinded chest radiologists independently evaluated subjective image quality and diagnostic confidence. Data were compared between the normal-dose and low-dose groups in five BW subgroups. Results Vessel attenuation did not differ between the normaldose and low-dose groups within each BW subgroup (P=1.0). The CNR was higher with the normal-dose compared with the low-dose protocol (P<0.006) in all BW subgroups except for the 90-99 kg subgroup (P=0.812). Subjective image quality and diagnostic confidence did not differ between CT protocols in all subgroups (P between 0.960 and 1.0). Conclusions Subjective image quality and diagnostic confidence with 80 kVp CTPA is not different from normal-dose protocol in any BW group up to 100 kg. Key Points • 80 kVp CTPA is safe in patients weighing <100 kg • Reduced radiation and iodine dose still provide high vessel attenuation • Image quality and diagnostic confidence with low-dose CTPA is good • Diagnostic confidence does not deteriorate in obese patients weighing <100 kg
Journal of Thoracic Imaging, 2014
The aim of the study was to compare the effects of different respiratory maneuvers in computed tomography pulmonary angiography for the diagnosis of pulmonary embolism (PE) on the contrast enhancement of pulmonary circulation and on the quality of lung window images. Materials and Methods: A retrospective analysis of 520 examinations, half obtained after deep inspiration followed by breathholding and half solely during breath-holding. Subjective quality analyses and objective measurements of pulmonary arterial enhancement and lung parenchyma attenuation were performed. Results: Elimination of deep inspiration reduced suboptimal opacification of the pulmonary artery (PA), from 7.3% to 2.7%, with 2.7% of the deep inspiration scans having attenuation values <150 Hounsfield units (HU). The prevalence of PE was similar between the groups (19% vs. 23%, respectively), with excellent interobserver diagnostic agreement (k = 0.89 to 0.91). Lung windows were compromised in 6.9% of the studies with respiratory pause, and these examinations had a higher attenuation of the lung parenchyma (median: À709.8 HU) compared with deep inspiration (À794.8 HU). A positive correlation between attenuation of the PA and the ascending aorta was observed (r = 0.40 to 0.56). Conclusions: Eliminating deep inspiration before image acquisition had opposite effects with the same magnitude: it caused a reduction in inadequate PA enhancement at the cost of an increased number of nondiagnostic lung images and did not compromise diagnostic consistency for PE.