Reducing amount of contrast agent after compression of right brachial artery using a blood pressure cuff in computed tomography cerebrovascular angiography

Abstract

OBJECTIVE:

To invastgate feasibility of low-dose contrast agent in cerebral computed tomography angiography (CTA) to alleviate side effects.

METHOD:

Siemens’ Somatom Definition AS+CT scanner, Heine’s blood pressure monitor G7-M237 (BP cuff) and Ultravist contrast agent (370 mg Iodine/ml) are used. CTA is acquired using following scan parameters including slice thickness of 1mm, image acquisition parameters of 128×0.6 mm, pitch size of 0.8 mm, 175 effective mAs, 120 kVp tube voltage, scan delay time of 3 seconds, and the scan time of 4 seconds. This study is conducted by securing the IV route in the left antecubital vein before injection of contrast agent, wrapping BP cuff around the branchial artery of the opposite right arm after setting the pressure to 200 mmHg. Then, the injection rate of the contrast agent is fixed at 4.5 cc/sec and contrast agent was injected in three different amounts (70, 80, and 100 cc). Bp cuff is released from this moment when HU value reachs 100.

RESULT:

In this study, the mean HU values measured from common carotid artery are 412.45±5.89 when injecting 80cc contrast agent and using BP cuff and 399.64±5.51 when injecting 100 cc contrast agenet and not using BP cuff, respectively. In middle cerebral artery M1, the mean HU values are 325.23±38.29 when injecting 80cc contrast agent and using BP cuff and 325.00±30.63 when injecting 100cc contrast agent blood and not using pressure cuff, respectively. Difference of mean HU values is not statistically significant (p > 0.05) with and without using BP cuff.

CONCLUSION:

This study demonstrates that reducing amount of contrast agent is possible when the right brachial artery is compressed using BP cuff. Study results indicate that reducing 20% injection of contrast agent in CT cerebrovascular angiography can still yield comparable imaging results with conventional contrast angent usage, which implies that less side effects are expected with a contrast agent injection. Thus, this study can serve as a reference for potential reducing side effect during CT cerebrovascular angiography.

Keywords

Contrast agent right brachial artery blood pressure cuff computed tomography cerebrovascular angiography

1 Introduction

Computed tomography (CT) has bacome an essential tool for diagnostics on many clinical conditions with its mechanical and software develoments over the past decases. In addition, the number of examinations along with various methods are increasing explosively. Accordingly, computed tomography angiography (CTA) is an alternative to general angiography which has a high possibility of causing various complications [1]. The use of contrast agent in radiographic examinations has been rapidly increasing for diagnostic and therapeutic purposes over the past 30 years [2]. In 1969, Almen, developed the first hypotonic contrast agent such as metrizamide, which is new ionic and non-ionic hypotonic contrast agent [3]. This is the low osmotic contrast agent and is superior to those of the high osmotic contrast agent in terms of safety and angiography efficacy. However, although the incidence of side effects of non-ionic hypotonic contrast agent has been significantly reduced, the occurrence of side effects cannot be completely predicted or ruled out.

The types of contrast agent side effects can be greatly classified into two. One is related to the chemical toxicity of the contrast agent, the other produces adverse effects on body organs in proportion to the dose. It varies from mild hives, pruritus, vomiting, and nausea to cardiopulmonary arrest [4]. According to previous studies on the side effects of these contrast agent, these were high in patients with allergies, asthma, heart disease, and past drug side effects. For example, mild symptoms such as hives, itching, dizziness, and edema occurred, and severe side effects included dyspnea and cardiopulmonary arrest [3]. In addition, due to the high price of iodine-containing contrast agents as well as unexpected side effects, the use of contrast agent should be reduced while ensuring CTA [5]. The previous study was the majority of papers such as radiation exposure reduction due to scan parameters change such as tube current, tubes, and slices, etc. There were a number of discussions on the use of contrast agents of high drug side effects [5 –8]. According to previous paper, there was a research in studying the relationship between contrast injection speed and contrast agent amount [9]. However, there was nothing research to reduce the amount of contrast using this compression device module such as blood pressure cuff. By default, 2 cc/Kg is used when examining CT, for example, man of a weight of 70 kg should be used as 140 cc, but the contrast agent is too much. It causes serious side effects by contrast agent. Thus, it is universally enforced under cerebral CT angiography as 100cc of contrast agent.

In this study, we want to suggest a way to reduce the amount of contrast agent using blood pressure cuff (BP cuff) during the conventional contrast agent examination. We is to determine the decrease of contrast agent to the common carotid arteries (CCA) and middle cerebral arteries (MCA) after reducing the injection amount of the contrast agent and compressing right brachial artery under CT cerebrovascular angiography [10].

2 Materials and method

2.1 Study subjects

The subjects of this study were those who underwent CT cerebrovascular angiography among outpatients who visited Pusan National University Yangsan Hospital from July 2020 to December 2020. The subjects of this study were 80 patients, 47 males, and 33 females. The average age was 54.6 years old. In addition, the number of samples using 70cc, 80cc, 100cc contrast agent were 25, 27, and 28 patients. This study was divided into three groups considering the radiation exposure of the patients. The contrast agent amount of each group was injected into 70, 80, and 100 cc, as shown in Table 1.

Table 1
Three group classification according to the amount of contrast agent

Amounts of contrast agent Group I (70cc) Group II (80cc) Group III (100cc)

Patients (n) 25 27 28

Amounts of contrast agent	Group I (70cc)	Group II (80cc)	Group III (100cc)
Patients (n)	25	27	28

2.2 Research method

In this study, CT images were acquired using Siemens’ somatom definition AS + CT equipment. During the CT imaging scanning, Heine’s blood pressure monitor G7-M237 (namely, BP cuff) was used. Meanwhile, Ultravist (370 mg Iodine/ml) was used as the contrast agent used. Table 1 shows the scan parameters and protocol for CT cerebrovascular angiography.

2.2.1 CT image parameters

Slice thickness was set to 1 mm, image acquisition parameters were set to 128×0.6 mm, pitch was set to 0.8 mm, effective mAs was set to 175 mAs, tube voltage to 120 kVp, and scan delay time to 3 seconds, and the scan time to 4 seconds, as shown in Table 2.

Table 2
CT Image parameters

Slice thickness 1 mm

Acuisition 128^*0.6 mm

Pitch 0.8 mm

Effective mAs 175 mAs

Tube voltage 120 kVp

Scan delay time 3 sec

Scan time 4 sec

The patient scan time was determined by the Care Bolus 4D used in computed tomography cerebrovascular angiography. This was set to 100 of HU value at Region of Interest (ROI) of the left ventricle. The scan starts to obtain an arterial phase after 3 seconds from this moment that the HU value is reached 100. And then, X-ray emits and it takes 4 seconds that time.

2.2.2 Method of inspection

Figure 1(b) shows wrapping BP cuff around the branchial artery of right arm and securing the IV route in the left antecubital vein before injection of the contrast agent. The pressure BP cuff was set to 200 mmHg. And then, we inject the contrast agent. The injection rate of the contrast medium was fixed at 4.5 cc/sec. The BP cuff is released from this moment that the HU value is reached 100.

Fig. 1

(a) G7-M237 (BP cuff) (b) preparation: wrapping BP cuff around the branchial artery of the right, securing the IV route in the left antecubital vein.

2.2.3 Measurement of ROI region

We measured HU value against 70 cc, 80 cc and 100 cc (contrast agent) in CCA and MCA M1 by compressing the right brachial arm or without compression of the right brachial. All HU value is the average value measured on both sides of CCA and MCA M1, as shown in Fig. 2.

Fig. 2

Region of measurement point (a) CCA bifurcation, (b) MCA M1 portio.

In order to measre HU value, we determined ROI of CCA and MCA M1, as shown in Fig. 2. The HU values were measured at CCA bifurcation and MCA M1, as shown in Fig. 2 (a), (b). Two ROIs of Fig. 2 (a) indicate the right CCA and the left CCA before being branched to the inner diameter and external main artery, and two ROIs of Fig. 2 (b) are the most central of the lower right and left of the critical cerebral artery on the left.

Since the difference in measurement position between researchers may occur, we performed intra-class correlation coefficient to evaluate the measurement value reliability of two researchers. The measured value between the two researchers was almost matched because Intra-class correlation coefficient (0.926) was high.

2.3 Statistical analysis

For statistical analysis of the data, SPSS version 26.0 was used, each contrast agent injection amount and BP cuff use were used as independent variables, and the HU (Hounsfield Unit) values of both common carotid arteries (CCA) and middle cerebral arteries (MCA) were used as dependent variables, and the mean and standard deviation were presented as descriptive statistics. The paired-sample T-test, which is a statistical method of parametric testing, was performed to determine that there was statistical significance at the 95% confidence interval (p-value < 0.05).

3 Result

According to Table 3, after 70cc injection, the mean HU value before compression of the brachial arm was 359.12±4.82 and 376.48±5.03 after compression for CCA. After 80cc injection, the mean HU value before compression of the brachial arm was 396.59±5.50 and 412.45±5.89 after compression for CCA. After 100cc injection, the mean HU value before compression in the brachial arm was 399.64±5.51 and 414.06±5.94 after compression for CCA.

Table 3
Paired-sample t-test of both CCA HU value according to the use of BP cuff or not according to the use of contrast agent 70, 80, 100cc (N = 80)

Contrast agent Usage (cc) BP cuff use or not Both CCA (HU) p-value

70 use 376.48±5.03 p < 0.023^*

not 359.12±4.82

80 use 412.45±5.89 p < 0.025^*

not 396.59±5.50

100 use 414.06±5.94 p < 0.019^*

not 399.64±5.51

Contrast agent Usage (cc)	BP cuff use or not	Both CCA (HU)	p-value
70	use	376.48±5.03	p < 0.023^*
	not	359.12±4.82
80	use	412.45±5.89	p < 0.025^*
	not	396.59±5.50
100	use	414.06±5.94	p < 0.019^*
	not	399.64±5.51

(0.05 < p^*, 0.001 < p^**).

The result of measuring mean HU value of 70cc (contrast agent) was 376.48 when BP cuff was used, and 359.12 without use of BP cuff for both CCA. The differenec was approximately 17.36 HU value. In the case of 80 cc (contrast agent), the mean HU value was 412.45 when BP buff was used, and 396.59 without use of BP cuff for both CCA. The differenec was approximately 15.86 HU value. In the case of 100 cc (contrast agent), the mean HU value was 414.06 when Bp buff was used, and 399.64 without use of BP cuff for both CCA. The differenec was approximately 14.42 HU value. All values were statistically significant (p < 0.05) for both CCA.

As shown in Table 4, after 70cc injection, the mean HU value for M1 region of MCA was 238.03±50.56 before compression of the brachial arm and 277.90±38.00 after compression. After 80cc injection, the mean HU value was 297.64±34.19 before compression and 325.23±38.29 after compression for the M1 region of MCA. And after 100cc injection, the mean HU value for the M1 region of MCA was 325.00±30.63 before compression and 342.29±32.62 after compression.

Table 4

Paired-sample t-test of both middl cerebral artery M1 HU value according to the use of BP cuff or not according to the use of contrast agent 70, 80, 100cc (N = 80)

Contrast agent Usage (cc)	BP cuff use or not	Both MCA M1 (HU)	p-value
70	use	277.90±38.00	p < 0.029^*
	not	238.03±50.56
80	use	325.23±38.29	p < 0.033^*
	not	297.64±34.19
100	use	342.29±32.62	p < 0.041^*
	not	325.00±30.63

(0.05 < p^*, 0.001 < p^**).

The result of measuring the both MCA MI HU value of 70cc (contrast agent) was 277.90 when BP buff was used, and 238 without use of BP cuff for both MCA M1. The differenec was approximately 39.87 HU value. In the case of 80 cc (contrast agent), the mean HU was 325 when BP buff was used, and 297.64 without use of BP cuff. The differenec was approximately 27.59 HU value. In the case of 100 cc (contrast agent), the mean HU value was 342.29 when BP buff was used, and 325.00 without use of BP cuff. The differenec was approximately 14.42 HU value. Like CCA, all values were statistically significant (p < 0.05) for both MCA M1.

Since blood flows with sufficient contrast agent is supplied due to the wide cross-sectional area of CCA’s blood vessels, 3D Reconstruction of the CT image was implemented in contrast agent (80 cc) during the scan time. Thus, there was little difference between contrast agent (100 cc) and contrast agent (80 cc) at experimental result. In MCA M1, the cross-sectional area of the blood vessels was less than the CCA, so that other experimental results were shown when compared CCA. Based on the results of the MCA M1, we compared contrast agent (80 cc) with contrast agent (100 cc).

As shown in Table 5, as a result of measuring CCA HU value of contrast agent (80 cc), it was 412.45±5.89 when BP cuff was used. This was a difference of 13 HU value (399.64±5.51) when 100cc BP cuff was not used. It was not statistically significant (p > 0.05). With BP cuff (contrast agent 80 cc), we can get a much better 3D Reconstruction of the CT image than when we have not used BP cuff (contrast agent 100cc) and the amount of the contrast agent (20 cc) is reduced.

Table 5

Paired-sample t-test of both common carotid artery HU value according to the use of BP cuff or not according to the use of contrast agent 80 and 100cc (N = 80)

Contrast agent Usage (cc)	BP cuff use or not	Both CCA (HU)	p-value
80	use	412.45±5.89	p > 0.890
100	not	399.64±5.51

(0.05 < p^*, 0.001 < p^**).

As shown in Table 6, as a result of measuring the both MCA M1 HU value contrast agent (80cc), it was 325.23±38.2 9 when BP cuff was used. This was similar to HU value (325.00±30.63) when 100 cc BP cuff was not used. It was not statistically significant (p > 0.05). Unlike CCA, there was little difference between the two HU values.

Table 6

Paired-sample t-test of both middl cerebral artery M1 HU value according to the use of BP cuff or not according to the use of contrast agent 80 and 100cc (N = 80)

Contrast agent usage(cc)	BP cuff use or not	Both MCA M1 (HU)	p-value
80	use	325.23±38.29	p > 0.993
100	not	325.00±30.63

(0.05 < p^*, 0.001 < p^**).

Figure 3 shows 3D reconstruction of the CT image of CCA and MCA M1 after administering 80cc contrast agent using BP cuff. Particularly, the brain aneurysms and vascular arterials in the brain vascular area are well visible to the MCA M1 region.

Fig. 3

3D reconstruction of the CT image of CCA and MCA M1 after administering 80cc contrast agent using BP cuff (a) Maximun intensity projection (b) Volume rendering technique in CT cerebrovascular angiography.

Generally, the amount of contrast agent (100 cc) is administered to implement the 3D reconstruction of the CT image well when BP cuff was not used [5]. In this study, we compared contrast agent (80 cc) when BP cuff was used and contrast agent (100 cc) when not used. Because HU value (80cc contrast agent) when BP buff was used was similar to HU value (100 cc contrast agent) when BP buff was not used.

Figure 4 shows the directional and speed of blood flow when BP Cuff is used. From Fig. 4, when BP Cuff is used, we knew that the direction of blood flow is generated and the blood flow rate increases. In order to implement CTA well, blood flow is an important factor. For checking how much effect when compressing the right upper arm with a BP cuff, head and neck blood flow of five adults was measured with an ultrasound Doppler mode, as shown in Fig. 4.

Fig. 4

Using ultrasound Doppler mode. None compression of CCA (a), and BP compression at right brachial artery of CCA (b) None compression of vertebra artey (c), and BP compression at right vertebra artery (d).

In a relaxed state, the blood flow velocity of the vertebral artery on the same side as the right carotid artery is measured using ultrasound Doppler mode and then the right brachial arm is compressed with a buff cuff at a pressure of 200 mmHg.

Generally, the mean artery blood flow velocity was 43 cm/sec [11]. The blood flow velocity by five research subjects selected was measured under 200 mmHg. When BP Cuff is used, the righ carotid blood flow velocity increased to 79.4 cm/sec and the right vertebral blood flow velocity increased to 60.3 cm/sec. But, left Arteries showed little increase in blood flow rate. So, Changes in blood flow velocity in the contralateral left carotid artery and vertebral artery were excluded from this experiment in this study.

4 Discussion

Recently, in the field of radiology, various examinations and even dynamic examinations of blood vessels and heart are being performed due to the development of CT imaging technology and the advanced equipment [12]. In accordance with this phenomenon, the range of options such as the type of contrast agent, injection amount, and injection speed is expanding according to the examination site. In particular, injection time and examination time of the contrast agent are very important in the examination method of blood vessels and heart [13]. However, with the development of imaging devices in the field of radiology, there are several types of contrast agent and they are used in large quantities. As a result, the probability of side effect of contrast agent was increased. Therefore, it is vital to explore ways in which contrast agent can be used at as low a dose as possible.

According to many reported study, the incidence of side effects of non-ionic contrast agent is significantly lower that of ionic contrast agent [14]. Nevertheless, side effects such as mild urticaria, vomiting, and nausea to severe cardiopulmonary arrest, occur suddenly and without warning by non-ionic contrast agent.

Side effects caused by contrast agent appears in various clinical forms, and the mechanism of occurrence is also complicated, so detailed investigation has not yet been made [15]. In addition, the risk factors for side effects known so far include a history of side effects of contrast agent, allergies, the age group of 20–50 years, asthma, women, and beta blocker users of heart disease patients, but the factors that can accurately predict it are not clear. However, death due to side effects frequently occurs. It is commonly known that many of these deaths are due to changes in the heart by contrast agent [15]. In order to minimize the side effects of these contrast agent, it can be said that an appropriate contrast agent injection amount is necessary [16].

In this study, we compared HU value of CCA and MCA M1 about the amount of three contrast agents. If a blood flow containing more contrast agent for a scan time should be supplied, HU value will be increasing and a better 3D Reconstruction of the CT image can be implemented. However, the side effects are serious as the amount of contrast agents increases. Generally, for reducing side effects in the medical field, the amount of contrast agent (100 cc) is administered to implement the better 3D reconstruction of the CT image when BP cuff is not used [5].

As a result, we determined contrast agent (100 cc) without pressing the BP cuff by reference value. We compared HU value (70, 80 cc and 100 cc contrast agent injection) depending on the use of BP cuff. In this study, the important region is MCA M1 and CCA is only an auxiliary data to show the flow of blood flow. The most important part of universal cerebral vascular angiography is anterior cerebral artery and middle cerebral artery because cerebral infarction and aneurysm occurs well. So, 3D Reconstruction of the CT image should be well implemented at MCA M1.

In clinical practice, 3D angiography in vertebra, neuropathy and brain vascular disease is an essential examination. Particularlly, the brain aneurysms and vascular arterials in the brain vascular area are well visible to the MCA M1 region. Since the average blood flow rate of MCA M1(60.3 cm/sec) is slower than the CCA (79.4 cm/sec), the HU values are lower than CCA.

It is a scan delay time that sends a bloodstream that contains contrast agents from left ventricle to carotid arteries. After that, the part required for 4 seconds is scanned. After that, the part required of cerebrovascular for 4 seconds is scanned. A blood flow containing sufficient contrast agent for a scan time should be supplied, if the amount of contrast agent is less than 100 cc, 3D Reconstruction of the CT image is not well implemented. Generally, the amount of contrast agent (100 cc) is administered to implement the 3D reconstruction of the CT image well when BP cuff was not used. However, using BP Cuff, 3D Reconstruction of the CT Image is well implemented because the blood flow containing sufficient contrast agents due to fast blood flow rate is supplied during the CT scan period.

In our result, we showed that use of BP cuff is always higher HU value in the same contrast agent. The blood flow containing more contrast agents due to fast blood flow rate is supplied using BP cuff. So, HU value increases when BP cuff is used. When BP cuff is used (contrast agent 70 cc), HU value of both MCA M1 was 277.90±38.00. 250HU value is within the range that does not cause a problem in the 3D reconstruction of the CT image [17]. With BP cuff (contrast agent 80 cc), we can get a much better 3D Reconstruction of the CT image than when we have used BP cuff (contrast agent 70 cc). When BP Cuff (100 cc contrast agent) is not used, the amount of contrast agent will reduce 20 cc.

In this study, we demonstrated that the reduction of amount of contrast agent when the right brachial artery was compressed using the BP cuff. In other words, this can reduce the side effects by using a small amount of contrast agent. This will be considered the basis research result for tentatively reducing the side effects. In addition, the amount of contrast agent may not be sufficient for CT cerebrovascular angiography of the results of this study when the amount of contrast agent is reduced by 30% or more.

5 Conclusion

In this study, the computed tomography brain angiography despite reducing the contrast agent by 20% was well implemented. However, the ratio of reducing the amount of contrast agent injection may be slightly different in the anatomical examination and the examination protocol for each part of the computed tomography apparatus. In the future, as in this study, various studies are needed to reduce the amount of contrast agent injected by increasing blood flow not only in CT cerebrovascular angiography, but also in other examination sites.

Footnotes

Acknowledgment

This work was supported by a Research Institute for Convergence of Biomedical Science and Technology (30-2021-006), Pusan National University Yang-san Hospital.

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Slice thickness	1 mm
Acuisition	128^*0.6 mm
Pitch	0.8 mm
Effective mAs	175 mAs
Tube voltage	120 kVp
Scan delay time	3 sec
Scan time	4 sec

Reducing amount of contrast agent after compression of right brachial artery using a blood pressure cuff in computed tomography cerebrovascular angiography

Abstract

OBJECTIVE:

METHOD:

RESULT:

CONCLUSION:

Keywords

1 Introduction

2 Materials and method

2.1 Study subjects

Table 1 Three group classification according to the amount of contrast agent Amounts of contrast agent Group I (70cc) Group II (80cc) Group III (100cc) Patients (n) 25 27 28

2.2.1 CT image parameters

Table 2 CT Image parameters Slice thickness 1 mm Acuisition 128*0.6 mm Pitch 0.8 mm Effective mAs 175 mAs Tube voltage 120 kVp Scan delay time 3 sec Scan time 4 sec

3 Result

5 Conclusion

Footnotes

Acknowledgment

References

Table 1
Three group classification according to the amount of contrast agent

Amounts of contrast agent Group I (70cc) Group II (80cc) Group III (100cc)

Patients (n) 25 27 28

Table 2
CT Image parameters

Slice thickness 1 mm

Acuisition 128^*0.6 mm

Pitch 0.8 mm

Effective mAs 175 mAs

Tube voltage 120 kVp

Scan delay time 3 sec

Scan time 4 sec