**3.2 Morphometry: longitudinal quantification**

The ultrasonographic vascular parameters were recorded before and after stenting or balloon injury every second week up to 8 weeks to evaluate the vessel structure. The imaging and measurements were performed at the injured and stented segments of the arteries as well as at the intact segments free from intervention situated distally and proximally of the lesion or stent, as controls (**Figure 2A**). The distal part of the abdominal aorta was also imaged and analysed (**Figure 2B**).

We report in **Figure 2A** the values of the diameters and wall thicknesses of the stented and balloon-injured iliac arteries obtained for each animal. We chose to present each animal data to visualise the individual variations. For instance, after balloon injury, the vessel diameter increased transiently up to 14 days at the site of the injury. However, for two animals the diameter returned to initial size while staying enlarged for the third animal. A transient vessel enlargement was also observed for the distal and proximal controls. Likewise, the aorta wall thickness followed three different evolutions from day 14 to day 60 when considering each animal separately, the aorta wall thickness increased consistently for one animal (that received 3.5/8 the stent), alternate phases of augmentation and diminution for the second one (stent 3/13), while it decreased for the last rabbit (stent 2.5/9) after a transient increase (**Figure 2B**).

For the iliac arteries, as presented in **Figure 2C**, we calculated the mean percentage changes both, the wall thickness and the CSA relative to the pre-intervention. We showed a change of the wall thickness at the site of the stent. At day 14, the wall

**187**

**Figure 2.**

*High-Resolution Ultrasound Imaging System for the Evaluation of the Vascular Response to Stent…*

thickness showed a 133 ± 13% increase as compared with pre-intervention. For the proximal control segments, the wall thickness was not significantly altered over time. In contrast, following balloon injury, the wall thickness remained constant, over time with a slight, but statistically significant, reduction (94 ± 1%, p = 0.01)

*Longitudinal evaluation of the vessel structure. (A) The longitudinal measurements of the wall thickness and the lumen diameter of the right and left iliac arteries performed in different segments: at the site of the intervention (i.e. stent placement for the right artery and balloon inflation for the left artery) and at the proximal and distal uninjured segments as controls. Each animal and the corresponding stent are indicated and* 

*represented by a colour line. (B) Structure and VTI measured at the distal abdominal aorta. (C) Percentages of change in the crosssectional area of the vessel and the wall thickness relative to day 0 (preintervention, grey line) represented according to the vessel segment. Each line represents a different time post-intervention (day 14, 28 and 42). The results are shown as the mean of three animals and SEM. \* p < 0.05* 

In parallel, we report a significant increase (150 ± 9%, p = 0.03) in the CSA in

In contrast, the lumen CSA transiently increased in the left artery. The maximal significant change was 192 ± 35% in the injured segment as compared to the proximal (131 ± 31%, p = 0.02) and distal (145 ± 31%, p = 0.006) controls at day 14. The

observed after 42 days in the proximal segment.

*vs. day 0 and p < 0.05 vs. distal and proximal control segments.*

lumen area returned then to initial values.

the stented segment. The CSA remained elevated over time.

*DOI: http://dx.doi.org/10.5772/intechopen.88656*

*High-Resolution Ultrasound Imaging System for the Evaluation of the Vascular Response to Stent… DOI: http://dx.doi.org/10.5772/intechopen.88656*

#### **Figure 2.**

*Animal Models in Medicine and Biology*

**2.1 Statistics**

**3. Results**

(**Figure 2B**).

transient increase (**Figure 2B**).

**3.1 Stent placement**

ness (including intimal, media and adventitia layers).

considered significantly different when p < 0.05.

**3.2 Morphometry: longitudinal quantification**

The Bersoft Image Analysis software (Bersoft Technology and Software; Lunenburg, Canada) was used to quantify the vessel diameter and the wall thick-

Values are presented as mean ± SEM. The percentage changes in wall thickness, cross-sectional area and blood flow were analysed using two-way ANOVA; Fisher's LSD multi-comparisons were performed for the different segments and for the time effect. Linear regression and the parametric Pearson test were computed in a two-tailed manner. Analyses were performed using Prism software. Values were

We report the results from three rabbits that received a Coroflex Blue Neo BMS. In concordance with the standard clinical procedure, each animal received a stent with an appropriate diameter defined under angiographic monitoring. The respective diameter (mm) and length (mm) of the stents were 2.5/9, 3/13 and 3.5/8. The stent positioning and contralateral balloon injury were proximal from the abdominal aortic bifurcation for the two animals and distal for one animal, as shown in **Figure 1**. The interventions were performed successfully without complication. All animals appeared healthy without significant weight loss. No infection, oedema

The ultrasonographic vascular parameters were recorded before and after stenting or balloon injury every second week up to 8 weeks to evaluate the vessel structure. The imaging and measurements were performed at the injured and stented segments of the arteries as well as at the intact segments free from intervention situated distally and proximally of the lesion or stent, as controls (**Figure 2A**). The distal part of the abdominal aorta was also imaged and analysed

We report in **Figure 2A** the values of the diameters and wall thicknesses of the stented and balloon-injured iliac arteries obtained for each animal. We chose to present each animal data to visualise the individual variations. For instance, after balloon injury, the vessel diameter increased transiently up to 14 days at the site of the injury. However, for two animals the diameter returned to initial size while staying enlarged for the third animal. A transient vessel enlargement was also observed for the distal and proximal controls. Likewise, the aorta wall thickness followed three different evolutions from day 14 to day 60 when considering each animal separately, the aorta wall thickness increased consistently for one animal (that received 3.5/8 the stent), alternate phases of augmentation and diminution for the second one (stent 3/13), while it decreased for the last rabbit (stent 2.5/9) after a

For the iliac arteries, as presented in **Figure 2C**, we calculated the mean percentage changes both, the wall thickness and the CSA relative to the pre-intervention. We showed a change of the wall thickness at the site of the stent. At day 14, the wall

or arterial thrombosis was encountered. The wound area was normal.

**186**

*Longitudinal evaluation of the vessel structure. (A) The longitudinal measurements of the wall thickness and the lumen diameter of the right and left iliac arteries performed in different segments: at the site of the intervention (i.e. stent placement for the right artery and balloon inflation for the left artery) and at the proximal and distal uninjured segments as controls. Each animal and the corresponding stent are indicated and represented by a colour line. (B) Structure and VTI measured at the distal abdominal aorta. (C) Percentages of change in the crosssectional area of the vessel and the wall thickness relative to day 0 (preintervention, grey line) represented according to the vessel segment. Each line represents a different time post-intervention (day 14, 28 and 42). The results are shown as the mean of three animals and SEM. \* p < 0.05 vs. day 0 and p < 0.05 vs. distal and proximal control segments.*

thickness showed a 133 ± 13% increase as compared with pre-intervention. For the proximal control segments, the wall thickness was not significantly altered over time.

In contrast, following balloon injury, the wall thickness remained constant, over time with a slight, but statistically significant, reduction (94 ± 1%, p = 0.01) observed after 42 days in the proximal segment.

In parallel, we report a significant increase (150 ± 9%, p = 0.03) in the CSA in the stented segment. The CSA remained elevated over time.

In contrast, the lumen CSA transiently increased in the left artery. The maximal significant change was 192 ± 35% in the injured segment as compared to the proximal (131 ± 31%, p = 0.02) and distal (145 ± 31%, p = 0.006) controls at day 14. The lumen area returned then to initial values.
