Clinical Radiology 69 (2014) e86ee92
Contents lists available at ScienceDirect
Clinical Radiology journal homepage: www.clinicalradiologyonline.net
An individualized contrast material injection protocol with respect to patient-related factors for dual-source CT coronary angiography X. Zhu a, e, Y. Zhu a, e, H. Xu a, Y. Wan b, K.S. Choo c, G. Yang d, L. Tang a, *, Y. Xu a, ** a
Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou College of Medicine, Chang Gung University, Taoyuan, Taiwan c Department of Radiology, Pusan National University Yangsan Hospital Beomeo-ri, Mulgeum-eup, Yangsan-si, Gyeongnam, Republic of Korea d Laboratory of Image Science & Technology, School of Computer Science and Engineering, Southeast University, 2 Sipailou, Nanjing, Jiangsu, China b
article in formation Article history: Received 13 April 2013 Received in revised form 11 August 2013 Accepted 20 September 2013
AIM: To optimize contrast media (CM) injection protocols by individually tailoring the dose to the patient’s body weight (BW), body mass index (BMI) and heart rate (HR) at dual-source computed tomography coronary angiography (DSCT-CA). MATERIALS AND METHODS: A total of 423 patients were prospectively enrolled and were randomly assigned to four groups. The control group received 80 ml CM at 5 ml/s. For the HRoptimized group, the injection duration was the same as the scan duration plus 8 s. In the Body-optimized group, the dose of CM was tailored to BW and BMI. In the HR þ Body-optimized group, CM protocols tailored to body size and scan duration were applied. Individual variability of arterial attenuation and incidence of arterial over-opacification (attenuation >500 HU) in the four groups were compared. Correlations between BW, BMI, HR, and arterial attenuations were evaluated in the four groups, respectively. RESULTS: Reduced individual variability of arterial attenuation and a significantly lower incidence of arterial over-opacification were found in the Body-optimized group and HR þ Body-optimized group. Arterial attenuation was inversely correlated with BW, BMI, and HR in the control group, inversely correlated with BW and BMI in the HR-optimized group, and inversely correlated with HR in the Body-optimized group. In the HR þ Body-optimized group, arterial attenuation was not significantly correlated with BW, BMI, or HR respectively. CONCLUSION: CM protocols individually tailored to BW, BMI, and HR can lead to reduced individual variability and a lower incidence of over-opacification of arterial attenuation, but also can reduce the influence of BW, BMI, and HR on arterial attenuations at DSCT-CA. Ó 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
* Guarantor and correspondent: L. Tang, The First Affiliated Hospital of Nanjing Medical University, Department of Radiology, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China. Tel.: þ86 14751830090, þ86 025 83718836 5194; fax: þ86 025 83732804. ** Guarantor and correspondent: Y. Xu, The First Affiliated Hospital of Nanjing Medical University, Department of Radiology, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China. Tel.: þ86 13951891760, þ86 025 83718836 5194; fax: þ86 025 83732804. E-mail addresses: [email protected] (L. Tang), [email protected] (Y. Xu). e Both authors contributed equally to this work. 0009-9260/$ e see front matter Ó 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.crad.2013.09.018
X. Zhu et al. / Clinical Radiology 69 (2014) e86ee92
Introduction With the rapid evolution of multidetector (MD) row computed tomography (CT) and the advent of MDCT machines capable of imaging the coronary arteries even in patients with fast-beating hearts, coronary CT angiography (CCTA) has become an accurate method for non-invasive detection of coronary artery disease.1,2 However, proper enhancement is essential for the entire diagnostic process and all diagnostic images for coronary arteries. The optimal parameters for contrast media (CM), such as total iodine dose, iodine concentration, and injection rate and duration, have been extensively studied,3e6 and the effects of arterial attenuation at CCTA on the accuracy of coronary stenosis detection also have been evaluated.7e9 Primary patient-related factors that affect the degree of arterial enhancement at CCTA include body weight (BW)10e12 and cardiac output (CO).12,13 The degree of arterial enhancement correlates inversely with BW.10 The most commonly used scheme for adjusting the iodine dose to the BW is the use of a 1:1 linear scale (e.g., doubling the iodine mass when the patient’s body weight doubles).14 A previous study reported that coronary arterial enhancement increased with increasing body mass index (BMI) after the dose of CM was tailored to BW linearly.15 Further, only a few reports have been published on the use of BW-adapted injection protocols for CCTA.6,16 An additional important patient-related factor affecting the magnitude of CM enhancement is CO.12 It has been clinically observed that reduced CO results in delayed and increased arterial enhancement.13 Coronary arterial attenuation decreases with increased heart rate (HR) during dual-source CT coronary angiography (DSCT-CA), as CO increases with increasing HR.17 Also, the study of Tang et al.10 demonstrated that gender and age had no significant influence on coronary attenuation during DSCT-CA. However, to the authors’ knowledge, few data have been reported regarding the adjustment of the CM injection protocol according to BW, BMI, and HR during DSCT-CA. It was hypothesized that an individually optimized protocol with respect to the patient’s BW, BMI, and HR for DSCT-CA would increase the accuracy of diagnosis, as coronary attenuation would be improved due to decreased standard deviation of attenuation values in the coronary arteries irrespective of the patient’s body size and cardiac function parameters. The purpose of the present prospective study was to optimize the CM injection protocol to the individual so that the dose was adapted to BW and BMI, and the duration of the injection was tailored to the scan time.
Materials and methods
e87
undergoing DSCT-CA for evaluation of suspected coronary arterial disease were prospectively enrolled. Contraindications for CT in all patients were renal insufficiency and previous allergic reactions to iodinated CM. Exclusion criteria were previous coronary stent placement, bypass surgery, congenital and valvular heart diseases, and heart failure. Before the examination, a 20 G venous access was placed in a right antecubital vein. No extra b-blockade was administered to any patient prior to DSCT-CA examination unless the patient’s HR was >100 beats/min. The study protocol was approved by the local ethics committee and all participating patients gave written informed consent.
Imaging parameters All patients were examined with a first-generation of DSCT System (Somatom Definition; Siemens Medical Systems, Erlangen, Germany) with retrospective electrocardiograph (ECG) gating. Bolus tracking was used to trigger data acquisition by placing a region of interest (ROI) over the descending aorta and setting the trigger threshold to 100 HU. Scanning was performed in a craniocaudal direction covering the region from the aortic root above the ostium of the left coronary artery to the diaphragm in one breath-hold. CT parameters were as follows: 32 0.6 mm detector collimation, equalling a section acquisition of 64 0.6 mm using the flying focal spot technique; pitch adapted to the heart rate (0.2e0.5); 330 ms rotation time; 380 mAs tube currentetime product and 120 kV tube voltage. Scan time was determined by the pitch and scanning range before scanning.
CM injection protocols High-concentration CM (iopromide, 370 mg iodine/ml; Ultravist, Bayer Schering Pharma, Berlin, Germany), followed by a chaser bolus of 40 ml saline at the same rate, were administered with a mechanical power injector under automatic pressure monitoring (Dual Shot, MedRad, Indianola, IN, USA). All 423 patients were randomly assigned to one of four CM injection protocols. In the control group (n ¼ 112), a fixed iodine dose and fixed injection duration was applied without any adjustment to BW, BMI, or HR. In the HRoptimized group (n ¼ 101), CM injection duration was tailored to HR according to scan time. In the Bodyoptimized group (n ¼ 107), the CM dose was adjusted to BW and BMI. In the HR þ Body-optimized group (n ¼ 103), the CM dose was tailored to BW and BMI and the injection duration was adjusted to HR according to scan time. Detailed information regarding the four CM injection protocols is shown in Table 1.
Image evaluation Patients Between September 2010 and January 2011, 423 patients referred to Department of Radiology, the First Affiliated Hospital of Nanjing Medical University (200 women, 223 men; mean age 61.5 11 years; age range 28e86 years)
A section thickness of 0.75 mm, section increment of 0.5 mm, field of view (FOV) of 22 22 cm, and medium softtissue reconstruction algorithm (B26f) were used for the reconstruction of transverse images of the best diastolic and systolic phases. Coronary arterial attenuations were the
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X. Zhu et al. / Clinical Radiology 69 (2014) e86ee92
Table 1 Contrast material (CM) protocols in four groups.
Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28) Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28) Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28) Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28)
Control group
HR-optimized group
Body-optimized group
HR þ Body-optimized group
Dose (ml)
Flow rate (ml/s)
Injection duration(s)
80
5
16
80
80/(Scan time þ8)
Scan time þ8
CM dose/16s
16
CM dose/(scan time þ8)
Scan time þ8
1.24 1.10 1.00 0.91 1.24 1.10 1.00 0.91
BW BW BW BW BW BW BW BW
(kg) (kg) (kg) (kg) (kg) (kg) (kg) (kg)
BMI, body mass index; HR, heart rate; BW, body weight.
average densities within the ROI placed in the centre of the ascending aorta (AA) and coronary arteries with nearly 75% of its lumen area measured in either the diastolic or systolic phase, depending on which phase had sharper vessel borders. Attenuation was measured in the AA above the coronary ostia, left main coronary artery (LM), and proximal segments of the right coronary artery (RCA), left anterior descending (LAD), and left circumflex coronary arteries (LCX). Measurements were made by two independent radiologists with 8 and 6 years of experience in diagnostic CT who were blinded to the patient’s clinical data during the scan. Averages of their measurements were applied in the following statistical analysis.
Statistics Patient-specific and CM injection parameters and arterial attenuations were compared using one-way analysis of variance (ANOVA) and post-hoc multiple comparison with StudenteNewmaneKeuls test (SNK test). Pearson correlation analysis was performed to assess the relationship between BW, BMI, HR, and arterial attenuation in the four groups, respectively. A P-value
Contents lists available at ScienceDirect
Clinical Radiology journal homepage: www.clinicalradiologyonline.net
An individualized contrast material injection protocol with respect to patient-related factors for dual-source CT coronary angiography X. Zhu a, e, Y. Zhu a, e, H. Xu a, Y. Wan b, K.S. Choo c, G. Yang d, L. Tang a, *, Y. Xu a, ** a
Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou College of Medicine, Chang Gung University, Taoyuan, Taiwan c Department of Radiology, Pusan National University Yangsan Hospital Beomeo-ri, Mulgeum-eup, Yangsan-si, Gyeongnam, Republic of Korea d Laboratory of Image Science & Technology, School of Computer Science and Engineering, Southeast University, 2 Sipailou, Nanjing, Jiangsu, China b
article in formation Article history: Received 13 April 2013 Received in revised form 11 August 2013 Accepted 20 September 2013
AIM: To optimize contrast media (CM) injection protocols by individually tailoring the dose to the patient’s body weight (BW), body mass index (BMI) and heart rate (HR) at dual-source computed tomography coronary angiography (DSCT-CA). MATERIALS AND METHODS: A total of 423 patients were prospectively enrolled and were randomly assigned to four groups. The control group received 80 ml CM at 5 ml/s. For the HRoptimized group, the injection duration was the same as the scan duration plus 8 s. In the Body-optimized group, the dose of CM was tailored to BW and BMI. In the HR þ Body-optimized group, CM protocols tailored to body size and scan duration were applied. Individual variability of arterial attenuation and incidence of arterial over-opacification (attenuation >500 HU) in the four groups were compared. Correlations between BW, BMI, HR, and arterial attenuations were evaluated in the four groups, respectively. RESULTS: Reduced individual variability of arterial attenuation and a significantly lower incidence of arterial over-opacification were found in the Body-optimized group and HR þ Body-optimized group. Arterial attenuation was inversely correlated with BW, BMI, and HR in the control group, inversely correlated with BW and BMI in the HR-optimized group, and inversely correlated with HR in the Body-optimized group. In the HR þ Body-optimized group, arterial attenuation was not significantly correlated with BW, BMI, or HR respectively. CONCLUSION: CM protocols individually tailored to BW, BMI, and HR can lead to reduced individual variability and a lower incidence of over-opacification of arterial attenuation, but also can reduce the influence of BW, BMI, and HR on arterial attenuations at DSCT-CA. Ó 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
* Guarantor and correspondent: L. Tang, The First Affiliated Hospital of Nanjing Medical University, Department of Radiology, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China. Tel.: þ86 14751830090, þ86 025 83718836 5194; fax: þ86 025 83732804. ** Guarantor and correspondent: Y. Xu, The First Affiliated Hospital of Nanjing Medical University, Department of Radiology, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China. Tel.: þ86 13951891760, þ86 025 83718836 5194; fax: þ86 025 83732804. E-mail addresses: [email protected] (L. Tang), [email protected] (Y. Xu). e Both authors contributed equally to this work. 0009-9260/$ e see front matter Ó 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.crad.2013.09.018
X. Zhu et al. / Clinical Radiology 69 (2014) e86ee92
Introduction With the rapid evolution of multidetector (MD) row computed tomography (CT) and the advent of MDCT machines capable of imaging the coronary arteries even in patients with fast-beating hearts, coronary CT angiography (CCTA) has become an accurate method for non-invasive detection of coronary artery disease.1,2 However, proper enhancement is essential for the entire diagnostic process and all diagnostic images for coronary arteries. The optimal parameters for contrast media (CM), such as total iodine dose, iodine concentration, and injection rate and duration, have been extensively studied,3e6 and the effects of arterial attenuation at CCTA on the accuracy of coronary stenosis detection also have been evaluated.7e9 Primary patient-related factors that affect the degree of arterial enhancement at CCTA include body weight (BW)10e12 and cardiac output (CO).12,13 The degree of arterial enhancement correlates inversely with BW.10 The most commonly used scheme for adjusting the iodine dose to the BW is the use of a 1:1 linear scale (e.g., doubling the iodine mass when the patient’s body weight doubles).14 A previous study reported that coronary arterial enhancement increased with increasing body mass index (BMI) after the dose of CM was tailored to BW linearly.15 Further, only a few reports have been published on the use of BW-adapted injection protocols for CCTA.6,16 An additional important patient-related factor affecting the magnitude of CM enhancement is CO.12 It has been clinically observed that reduced CO results in delayed and increased arterial enhancement.13 Coronary arterial attenuation decreases with increased heart rate (HR) during dual-source CT coronary angiography (DSCT-CA), as CO increases with increasing HR.17 Also, the study of Tang et al.10 demonstrated that gender and age had no significant influence on coronary attenuation during DSCT-CA. However, to the authors’ knowledge, few data have been reported regarding the adjustment of the CM injection protocol according to BW, BMI, and HR during DSCT-CA. It was hypothesized that an individually optimized protocol with respect to the patient’s BW, BMI, and HR for DSCT-CA would increase the accuracy of diagnosis, as coronary attenuation would be improved due to decreased standard deviation of attenuation values in the coronary arteries irrespective of the patient’s body size and cardiac function parameters. The purpose of the present prospective study was to optimize the CM injection protocol to the individual so that the dose was adapted to BW and BMI, and the duration of the injection was tailored to the scan time.
Materials and methods
e87
undergoing DSCT-CA for evaluation of suspected coronary arterial disease were prospectively enrolled. Contraindications for CT in all patients were renal insufficiency and previous allergic reactions to iodinated CM. Exclusion criteria were previous coronary stent placement, bypass surgery, congenital and valvular heart diseases, and heart failure. Before the examination, a 20 G venous access was placed in a right antecubital vein. No extra b-blockade was administered to any patient prior to DSCT-CA examination unless the patient’s HR was >100 beats/min. The study protocol was approved by the local ethics committee and all participating patients gave written informed consent.
Imaging parameters All patients were examined with a first-generation of DSCT System (Somatom Definition; Siemens Medical Systems, Erlangen, Germany) with retrospective electrocardiograph (ECG) gating. Bolus tracking was used to trigger data acquisition by placing a region of interest (ROI) over the descending aorta and setting the trigger threshold to 100 HU. Scanning was performed in a craniocaudal direction covering the region from the aortic root above the ostium of the left coronary artery to the diaphragm in one breath-hold. CT parameters were as follows: 32 0.6 mm detector collimation, equalling a section acquisition of 64 0.6 mm using the flying focal spot technique; pitch adapted to the heart rate (0.2e0.5); 330 ms rotation time; 380 mAs tube currentetime product and 120 kV tube voltage. Scan time was determined by the pitch and scanning range before scanning.
CM injection protocols High-concentration CM (iopromide, 370 mg iodine/ml; Ultravist, Bayer Schering Pharma, Berlin, Germany), followed by a chaser bolus of 40 ml saline at the same rate, were administered with a mechanical power injector under automatic pressure monitoring (Dual Shot, MedRad, Indianola, IN, USA). All 423 patients were randomly assigned to one of four CM injection protocols. In the control group (n ¼ 112), a fixed iodine dose and fixed injection duration was applied without any adjustment to BW, BMI, or HR. In the HRoptimized group (n ¼ 101), CM injection duration was tailored to HR according to scan time. In the Bodyoptimized group (n ¼ 107), the CM dose was adjusted to BW and BMI. In the HR þ Body-optimized group (n ¼ 103), the CM dose was tailored to BW and BMI and the injection duration was adjusted to HR according to scan time. Detailed information regarding the four CM injection protocols is shown in Table 1.
Image evaluation Patients Between September 2010 and January 2011, 423 patients referred to Department of Radiology, the First Affiliated Hospital of Nanjing Medical University (200 women, 223 men; mean age 61.5 11 years; age range 28e86 years)
A section thickness of 0.75 mm, section increment of 0.5 mm, field of view (FOV) of 22 22 cm, and medium softtissue reconstruction algorithm (B26f) were used for the reconstruction of transverse images of the best diastolic and systolic phases. Coronary arterial attenuations were the
e88
X. Zhu et al. / Clinical Radiology 69 (2014) e86ee92
Table 1 Contrast material (CM) protocols in four groups.
Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28) Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28) Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28) Underweight (BMI < 18.5) Normal (18.5 BMI < 24) Overweight (24 BMI < 28) Obesity (BMI 28)
Control group
HR-optimized group
Body-optimized group
HR þ Body-optimized group
Dose (ml)
Flow rate (ml/s)
Injection duration(s)
80
5
16
80
80/(Scan time þ8)
Scan time þ8
CM dose/16s
16
CM dose/(scan time þ8)
Scan time þ8
1.24 1.10 1.00 0.91 1.24 1.10 1.00 0.91
BW BW BW BW BW BW BW BW
(kg) (kg) (kg) (kg) (kg) (kg) (kg) (kg)
BMI, body mass index; HR, heart rate; BW, body weight.
average densities within the ROI placed in the centre of the ascending aorta (AA) and coronary arteries with nearly 75% of its lumen area measured in either the diastolic or systolic phase, depending on which phase had sharper vessel borders. Attenuation was measured in the AA above the coronary ostia, left main coronary artery (LM), and proximal segments of the right coronary artery (RCA), left anterior descending (LAD), and left circumflex coronary arteries (LCX). Measurements were made by two independent radiologists with 8 and 6 years of experience in diagnostic CT who were blinded to the patient’s clinical data during the scan. Averages of their measurements were applied in the following statistical analysis.
Statistics Patient-specific and CM injection parameters and arterial attenuations were compared using one-way analysis of variance (ANOVA) and post-hoc multiple comparison with StudenteNewmaneKeuls test (SNK test). Pearson correlation analysis was performed to assess the relationship between BW, BMI, HR, and arterial attenuation in the four groups, respectively. A P-value
