Evaluation of the association of arterial blood inflow by the Doppler with the stiffness of the penile tunica albuginea by the 2D share wave elastography.
Poster No.: C-3245
Congress: ECR 2019
Type: Scientific Exhibit
Authors: O. Dynnyk, Y. Miroshnykov, S. Kerus, I. Natalenko; Kyiv/UA Keywords: Genital / Reproductive system male, Vascular, Elastography,
Ultrasound-Spectral Doppler, Ultrasound, Technology
assessment, Diagnostic procedure, Connective tissue disorders, Haemodynamics / Flow dynamics
DOI: 10.26044/ecr2019/C-3245
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Aims and objectives
An erection is a multifactorial and phased mechanism in the biomechanical sense. It is known that for the beginning, development and maintenance of an adequate erection, a necessary condition is a good blood inflow from the deep cavernous arteries through arterioles into the cavernous venous sinuses and the cessation outflow due to the veno- occlusive mechanism [1,2]. The three factors in erection are the most important: arterial inflow, relaxation of the smooth muscles of the trabeculae of the corpus cavernosus (CC) and rigidity of the tunica albuginea of the CC (TA CC). TA is a support for compression and occlusion of the subtunical veins.
Doppler studies of arterial blood flow during the development of erection today already have clear criteria for normal and pathological conditions. These are indicators of erection: an increase in peak systolic velocity (PSV), a decrease in end diastolic velocity (EDV) up to complete cessation of blood flow to diastole, or even often reverse the reverse flow of blood into diastole (diastolic return). These changes in velocity are reflected in the resistance index (RI). RI becomes close to 1 or even greater than 1 in the phase of a rigid erection, In healthy subjects, Doppler curves clearly correspond to the five phases of erection [3,4,5].
Doppler showed an insufficient increase in PSV and a decrease in EDV with ED (in other words, an insufficient increase in resistance to blood flow, RI) with vasculogenic ED. RI did not reach the desired value # 1. This also indicated an inadequate veno-occlusive mechanism []. Two situations are possible here: either TA CC was too malleable due to collagenopathy and its rigidity is insufficient to compress subtunial veins or arterial inflow and relaxation of trabeculae are insufficient for the development of pressure and compression of subtunial veins to TA [6,7] .
It was interesting to assess the relationship between the blood Doppler data, which characterizes the blood flow, and the 2 dimension share wave elastography (2D-SWE) data, which characterize the stiffness of cavernous sructures (TA and cavernosal tissue - CT CC), as important players in achieving erection [8].
The aim was to evaluate the effect of arterial blood flow by the Doppler on the stiffness of the TA CC by the 2D-SWE.
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Methods and materials
The evaluation stiffness of the TA was performed for 26 subjects: with normal erection ( age 25-67 years) and 168 patients with ED (age 22-74 years) according to the International erectile index. For all of these healthy subjects and patients we had provide by #-mode navigation of the Doppler modes (Color Doppler Mapping and Pulse Doppler modes). Navigation of the region of interest (ROI) and simple volume (SV) with real-time (RT) 2D-SWE was also performed on routine US equipment by Soneus P7 (Ultrasign, Ukraine) with linear broadband probe 5-12 MHz, aperture 38 mm.
To prevent the effect of precompression by the US probe on the artifact of increasing the stiffness of cavernous structures, a "gel pillow" and a rubber nozzle bandage were used.
Simultanesly the doppler and RT 2D-SWE were performed at rest and 10 minutes after pharmacologically induced erection by intracavernous injection of 10 µg PG E1.
The probe was applied in the proximal part of the CC and oriented longitudinally along the axis of the right and left CC.
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Results
The stiffness of TA ## significantly increased due to its tension with normal erection (healthy subjects): from the initial state 18,12±8,01 kPa to135,3±14,17 kPa (p<0,001 ) in the right ## and from 18,24±7,57 kPa to139,1±11,61 kPa (p<0,001 ) in the left ##. At the same time, #T ## stiffness significantly decreased in healthy subjects from the initial state 15,11±6,24 kPa to 7,8± 3,99 kPa (p<0,001 ) in the right ## and from 14,58±4,58 kPa to 7,94± 3,31 kPa (p<0,001 ) in the left ##.
In our opinion, the decrease in CT CC stiffness during normal erection is due to the relaxation of the smooth muscles of trabeculae under the action of nitric oxide and the parasympathetic nervous system, as well as due to an increase in the share of fluid inside the CC. As it is known, the liquid does not possess elasticity and does not generate shear waves [8, 9]. Fig. 1, 2, 3, 4.
The stiffness of TA ## in the group with ED not so significantly increased due to erection:
from the initial state 14,03±1,32 kPa to 32,14± 7,89 kPa (p<0,001 ) in the right ## and from 14,20±7,57 kPa to 31,77±7,75 kPa (p<0,001 ) in the left ##. In the group with ED, the rigidity of the TA also increased, but did not reach the threshold of 100 kPa.
At the same time, #T ## stiffness in the group with ED not so significantly decreased from the initial state 11,92±1,11 kPa to 8,7± 3,16 kPa (p<0,001 ) in the right ## and from 12,30±8,68 kPa to 8,68± 2,93 kPa (p<0,05 ) in the left ##. Fig. 5, 6, 7.
A correlation analysis of the stiffness of the TA CC according to RT 2D-SWE and PSV according to the Doppler data in the combined group of healthy subjects and patients with ED was carried out.
There was found positive medium correlation of peak systolic velocity (PSV) in the cavernous artery (CA) with stiffness of the TA right CC (r=0, 32; #<0,001) and similar PSV in the CA with stiffness of the TA left CC (r=0, 30; #<0,001). The negative medium correlation was unreliable of end diastolic velocity (EDV) in the CA with stiffness of the TA right CC (r = - 0,38; #<0,09) and similar EDV in the CA with stiffness of the TA left CC (r = - 0,39; #<0,18). Effective erection was achieved when the stiffness of TA CC exceeded 125 kPa or more. Fig.8.
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Images for this section:
Fig. 1: RT 2D-SWE. High stiffness of the TA CC during normal erection.
© Institute of Elastography - Kyiv/UA
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Fig. 2: RT 2D-SWE. The middle stiffness of the subtunical layers of the CT CC during normal erection. Compression point of subtunical veins due to veno-occlusion mechanism.
© Institute of Elastography - Kyiv/UA
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Fig. 3: RT 2D-SWE. Low stiffness of the central layers of the CT CC during normal erection.
© Institute of Elastography - Kyiv/UA
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Fig. 4: Doppler. Absence of diastolic blood flow during normal erection.
© Institute of Elastography - Kyiv/UA
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Fig. 5: RT 2D-SWE. Low (subthreshold) stiffness of the TA CC in patient with ED .
© Institute of Elastography - Kyiv/UA
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Fig. 6: RT 2D-SWE. Low stiffness of the central layers of the CT CC in patient with ED.
© Institute of Elastography - Kyiv/UA
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Fig. 7: Doppler. Persistence of diastolic blood flow in violation of the veno-occlusal mechanism in patient with ED.
© Institute of Elastography - Kyiv/UA
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Fig. 8: Correlation of the stiffness of the TA CC according to the RT 2D-SWE data and PSV according to the Doppler data in the combined group of healthy subjects and patients with ED.
© Institute of Elastography - Kyiv/UA
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Conclusion
Doppler blood flow assessment during erection plays an important role in determining the cause of ED. ED occurs when an ineffective interaction of several factors: increased arterial inflow, smooth muscle relaxation trabeculae of the #T CC, mechanical tension of the TA ## and reduction of venous outflow by veno-occlusive mechanism.
Obviously, the increase of the CC stiffness provides a rigid erection. But the dynamics of erection and the distribution of stiffness into the cavernous structures themselves have not yet been sufficiently studied. According to our data, based on the use of an innovative method of US real-time 2-dimensional shear wave elastography (RT 2D-SWE) penile structures, this distribution of stiffness is of a gradient and reciprocal nature. We showed the dynamics of the stiffness of TA CC and the cavernosal tissue of CC itself (CT CC) during normal erection. We observed reciprocal mutual relations of stiffness of the TA and CT CC. When the stiffness TA CC increased 2.5-3 times, then the CT CC stiffness decreased in the centropetal direction during an adequate erection. We have proposed a scheme of the concentric layers around deep cavernosal artery for the stiffness gradient of the CT CC during erection: the most rigid were the subtunical layers [8, 10, 11, 12].
We believe that Doppler registration in diastole of arresting and / or reversing arterial blood flow in cavernous arteries during normal erection may find an explanation in the mechanical properties of the CT CC and TA CC. It is known that the speed and direction of blood in vessels in general and in arteries in particular corresponds to the pressure gradient []. In the case of a normal erection, there comes a moment in diastole, when blood pressure in the cavernous arteries is balanced with pressure in the venous cavernas. Doppler demonstrates the absence of blood movement in diastole. Negative diastolic blood flow (reverse) occurs, in our opinion, at the time of complete occlusion of the subtural veins. Excessive portions of blood enter the caverns during systole and elastically stretch the TC CC and AT CC. 2D SWE registers high rigidity TA. After completion of the systole the pressure in the aorta decreases and the elastic forces of the cavernous tissue (trabeculae) and TA CC elastically contract and thereby create a centropetal pressure gradient [8, 13].
Excessive portions of blood that have entered the caverns in systole are forced back into the cavernous arteries during diastole. Naturally, the decisive condition for the registration of blood reverse in the cavernous arteries is the biomechanical viability of a rigid TA CC.
Fig. 9, 10, 11, 12.
In the case of vasculogenic ED, the doppler cannot register reversal of diastolic blood flow to, since there are no conditions for the flow of excess blood through the arteries and the realization of the veno-occlusive mechanism. Anterograde blood leakage occurs through the veins, which reflects the Doppler in the form of prolonged anterograde diastolic blood flow [12, 13, 14] .
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Conclusion. The Doppler PSV (arterial inflow) correlates with stiffness of the TA CC that provides a normal erection. Increasing the stiffness of TA CC and decreasing the stiffness of CT CC are the 2D-SWE general indicators of effective erection.
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Images for this section:
Fig. 9: RT 2D-SWE. High stiffness of the TA CC during normal erection.
© Institute of Elastography - Kyiv/UA
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Fig. 10: RT 2D-SWE. The middle stiffness of the subtunical layers of the CT CC during normal erection. Compression point of subtunical veins due to veno-occlusion mechanism.
© Institute of Elastography - Kyiv/UA
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Fig. 11: RT 2D-SWE. Low stiffness of the central layers of the CT CC during normal erection.
© Institute of Elastography - Kyiv/UA
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Fig. 12: Doppler. Reverse of diastolic blood flow during normal erection.
© Institute of Elastography - Kyiv/UA
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Personal information
Dynnyk Oleh; MD, PhD, Radiologist,
Institute of Elastography, Kyiv.
e-mail: [email protected] Cell number: +380503319635.
Miroshnykov Yaroslav O., MD, PhD, Andrologist, urologist.
Family Medicine Institute Plus, Kyiv.
e-mail: [email protected] Cell number: +380675023864.
Kerus Sergiy V., MD, Radiologist.
Family Medicine Institute Plus, Kyiv.
e-mail: [email protected]
Cell number: +380502900159.
Natalenko Ihor L., MD, Radiologist, urologist.
Family Medicine Institute Plus, Kyiv.
e-mail: [email protected] Cell number: +380633270622.
Page 19 of 21
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