Construction And Characteristics Of3D Digitized Model Of Uterine Leiomyoma Arterial Network

Uterine leiomyoma, the most common benign, solid, pelvic tumors in women, occur in20%-40%of women in their reproductive years. Increased menstrual flow caused by leiomyomas, infertility and oppression symptoms seriously affect the patient’s health. Uterine artery embolization (uterine artery embolization, UAE), as a new method of uterine leiomyomas treatment, became more and more porpular for its minimal invasion, reduced intraoperative blood loss and duration of surgery, short hospital stay and rapid recovery. UAE reported in the literature for more than90%of patients with uterine leiomyomas, menstruation, pelvic pain and related symptoms mass effective. Compared with hysterectomy and myomectomy, uterine artery embolisation (UAE) has substantial merits such as minimal invasion, reduced intraoperative blood loss and duration of surgery, short hospital stay and rapid recovery.Efficacy of UAE has been affirmed, however, not all patients had good effect, there was still a small portion of patients had bad efficacy or recurrence in a short time after UAE. In addition the biological characteristics of the tumor, distribution of embolic agents and degree of embolization, both closely related to the vascular network of leiomyoma, affect efficacy of UAE. As we all know, the blood supply of uterine leiomyoma is the foundation of the UAE, some researchers have demonstrated that the type of blood supply and blood flow in uterine leiomyoma is associated with clinical efficacy of UAE.In recent treatment, detailed information of blood supply to leiomyomas before UAE is lack, leading the uneven distribution of embolic agents and incomplete thrombosis. But in the current UAE, due to leiomyomas could not clear the blood supply before surgery, either choice or assignment of cases embolic agents are often based on clinical experience, there is a big subjectivity and arbitrariness, affecting the efficacy of further improved. If the UAE before surgery that is able to clear the blood supply leiomyomas:uterine artery origin, the vascular supply and vascularity of uterine leiomyoma, making appropriate preoperative plans, will be beneficial to the safety and effectiveness of the UAE. Therefore, the study of characteristics of uterine leiomyoma arterial network is necessary.The study was divided into three parts, Part One:On the basis of pre-built network of pelvic arteries above, based on CT angiography (CT angiography, CTA) original dataset initially built in vivo3D digitized model of uterine leiomyoma vascular network and observe the characteristics of the model, in order to further increase the sample constructed to provide research-based in vivo uterine leiomyomas arterial vascular network digital three-dimensional models. Part Two:to build the body of3D digitized model of uterine leiomyoma vascular network refinement process to identify the myometrium and leiomyoma vascular blood vessels, blood supply and analyze the characteristics of different types of uterine leiomyomas model. Part Three:uterine leiomyomas arterial vascular network digital three-dimensional model based on analysis of the source of leiomyomas feeding artery, blood type, blood richness, provide vascular anatomical basis for guidance UAE, cases selection, a reasonable allocation of surgical procedures and intraoperative embolization agent predict the efficacy.Part One Preliminary construction of3D digitized model of uterine leiomyoma arterial network[Objective]Application CTA scanning technology and digital three-dimensional reconstruction techniques to explore the construct of uterine leiomyomas in vivo3D digitized model of uterine leiomyoma arterial network, compare the model with the DSA images.[Methods]From September2011to December2011,20patients diagnosed uterine leiomyoma were confirmed with ultrasound, with strong desire to retain uterus and/or fear for surgery were eligible for our study. All patients received pelvis dual-source CTA scan at the Nan fang Hospital of Southern Medical University. Mimics software through via automatic positioning images, organize pictures, the interpolation processing, the threshold growth to build3D digitized model of uterine leiomyoma arterial network, observed characteristics of the model, CTA datasets constructed explore the construct of uterine leiomyomas in vivo arterial vascular network digital three-dimensional model approach. Select the appropriate model construction methods. UAE surgery patients collected digital subtraction angiography (DSA) images, construct DSA arteries in vivo uterine leiomyomas digital three-dimensional network model and UAE-based intraoperative angiography by comparing image data sets verify the feasibility of construction methods, and compare the model with DSA images in UAE.[Results]In this study, CTA true representation at all levels of abdominal and pelvic arteries. Uterus and uterine leiomyoma vascular network were displayed clearly in3D digitized model of uterine leiomyoma vascular network based on CTA datasets, location and size of the leiomyoma could be identified exactly. Adjusting the density of the vascular network by changing threshold, the blood perfusion process could be simulated in some degree, vascular network of leiomyoma and different levels of uterine arteries branches such as arcuate artery and spiral arteries could be distinguished. The model could be revolved in any angle and adjusted the size, the branches and origins of arteries could be observed in three-dimensional space.When the patients underwent UAE, intraoperative angiography DSA observation shows that two-dimensional images of them were consistent with DSA.[Conclusion]Computer-based three-dimensional reconstruction of CT imaging data sets can build the ideal uterine leiomyomas in vivo3D digitized model of uterine leiomyoma arterial network, CT angiography was a reliable tool to construct model.Part Two Post-processing of3D digitized model of uterine leiomyoma arterial network[Objective]Uterine leiomyomas arterial vascular network digital three-dimensional model refinement processing CT angiography (CTA) to build three-dimensional reconstruction techniques to analyze the characteristics of uterine leiomyomas and uterine blood vessels, and the effects of different types of uterine leiomyomas vascular network.[Methods]From December2011to September2012,72consecutive patients, diagnosed uterine leiomyoma were confirmed with ultrasound, with strong desire to retain uterus and/or fear for surgery were eligible for our study. All the patients received pelvis dual-source CTA scan at the Nan fang Hospital of Southern Medical University. The patients’age ranged from22to54(mean40.3±6.4) years.69patients had a history of pregnancy, among them,7patients had a history of cesarean section. Other patients had no history of pelvic surgery.39patients underwent UAE, and33patients underwent myomectomy. All patients signed informed consent before CTA scan. Ethical approval for the study was obtained from the ethics committee of Nan fang Hospital of Southern Medical University.CTA data collection and model construction methods were the same as Part I. The CT images were firstly segmented using segmentation tools, such as threshold, region growing, boolean operation, edit mask, et al. to extract different tissues. The uterine leiomyoma vascular network of interest was isolated by setting appropriate gray level thresholds (100-150Hu) according to the display of the uterine artery to obtain the vascular rim. Once the whole uterine leiomyoma vascular network profile was obtained, a surface rendering technique was used with a reconstructed interval of1mm to rapidly reconstruct the3D vascular network. Meanwhile, a volume rendering technique was employed to visualize the3D vascular network without any segmentation.[Results]Characteristics of uterus and uterine leiomyoma vascular networkUterus was supplied by bilateral uterine arteries, uterine arteries of leiomyoma patients got enlarged, accompanied by tortuous branches. Two major branches, the intramuscular uterine branch and the cervicovaginal branch, originated from the uterine artery. The intramuscular uterine artery branched into arcuate arteries while ascending along the uterine body and the arcuate arteries underwent further subdivisions as they traveled to form the spiral arteries. The intramuscular uterine artery had branches to the fundus of the uterus, the ovary and the oviduct as it traveled towards the uterine horn, supplying blood for the uterine body, the ovary and the oviduct. The cervicovaginal artery was smaller than the intramuscular uterine artery and branched to supply mainly the cervix and a little the vagina. The blood supply of the uterine artery was ipsilateral with few small communicating branches between the two sides of the spiral arteries.Uterine leiomyoma vascular network had no communicating branches compared to that of the uterus, feeding artery of uterine leiomyoma, which was significantly thicker than the arcuate artery, originated from for the intramuscular uterine branch. Feeding artery formed outer layer of uterine leiomyoma at surface of the leiomyoma. The vascularity of leiomyoma was characterized as two layers of vascular net. The superficial thick layer spherically surrounded the surface of leiomyoma, with no highly structured vasculature. With dense capillary network, the other vascular layer, was found inside the leiomyoma.Characteristics of different types of leiomyomaVascular network of different types of uterine leiomyoma has their own characteristics.Intramural leiomyoma The hemispherical uterine leiomyoma vascular network is protruding from the surface of the uterine, but not dissociate from the uterine vascular network, contour of leiomyoma could be distinguished. Sometimes the normal myometrium vasculature was pushed aside by large intramural leiomyoma, becoming non-dominant vasculature. The siphon effect of blood flow could be observed.Subserosal leiomyoma Uterine leiomyoma vascular network dissociated from that of uterus, connected to the uterus through the feeding artery. Contour and size of the leiomyoma were showed clearly. There was a special type of uterine leiomyoma vascular network in nine cases of subserosal leiomyoma. The radialized feeding arteries extended into the leiomyoma, Distal vasculature was relatively sparse.Submucosal leiomyoma Uterine leiomyoma vascular network was surrounded by that of uterus, with rich blood supply. Only enlarged uterine vascular network could be observed, leiomyoma was unclear. Contour of leiomyoma could be identified clearly after transparency of the model was adjusted by using Mimics10.01software.Multiple leiomyomas vascular network had corresponding appearance according to the position of the leiomyoma.[Conclusion]3D digitized model of uterine leiomyoma vascular network based on CTA and reconstruction software is reliable, vascular network of uterus and uterine leiomyoma can be identified exactly by using of the model, it provides a useful reference for the preoperative evaluation and the teaching in clinical practice.Part Three Characteristics of3D digitized model of uterine leiomyoma arterial network[Objective]To investigate the characteristics of blood supply to the uterus and uterine leiomyoma by using of the3D digitized model of uterine leiomyoma arterial network based on the computed tomography angiography (CTA) data.[Methods]From December2009to October2013,151consecutive patients, diagnosed uterine leiomyoma were confirmed with ultrasound were eligible for our study. Patients with current pregnancy, endometrial hyperplasia, cervical, uterine, or ovarian carcinoma, pelvic inflammatory disease, and presence of any contraindications for angiography were excluded for CTA and UAE. All the patients received pelvis dual-source CTA scan at the Nan fang Hospital of Southern Medical University. The patients’age ranged from22to63(mean40.77±6.72) years. All patients signed informed consent before CTA scan. Ethical approval for the study was obtained from the ethics committee of Nan fang Hospital of Southern Medical University.CTA data collection and model construction methods were the same as Part Ⅱ. Based on3D digitized model of uterine leiomyoma arterial network, the vascular supply of uterine leiomyoma was categorised as one of four types:(1) Type Ⅰ (unilateral predominant);(2) Type Ⅱ (bilateral balanced);(3) Type Ⅲ (single unilateral uterine artery);(4) Type Ⅳ (single ovarian artery). The enhancement degree compared with the myometrium and vascular network of uterine leiomyoma during the DSA process was considered to be the determinant factor for the classification. We qualitatively assigned the vascularity of uterine leiomyoma to one of four grades:(1) Extremely hypervascular;(2) Hypervascular;(3) Isovascular;(4) Hypovascular.[Results]The vascular supply of uterine leiomyomaIn this study, all of uterine leiomyomas by uterine artery or ovarian artery, superior mesenteric artery was not found, bladder, arteries and other abnormal arterial blood supply to the leiomyoma. According to the blood supply of leiomyomas and bilateral sources of blood supply to the leiomyomas proportion of the blood supply will be divided into four types, except Type IV is entirely ovarian artery, the other three types are mainly in the uterine artery. In this study,14cases difficult to identify blood type. Identified107patients blood type, found that Type Ⅰ (unilateral predominant) accounted for up to49patients (45.79%), followed by type Ⅱ (bilateral balanced),47cases (43.39%), type Ⅲ (single unilateral uterine artery) and type Ⅳ (single ovarian artery) were7cases (5.54%) and4cases (3.74%).The vascularity of uterine leiomyomaAccording leiomyomas vascular density relative to normal myometrium divided into four types, which account for up to hypervascular type,47cases (38.84%) followed by Extremely hypervascular type,35cases (28.93%), Hypovascular and Isovascular type were21cases (17.36%) and18patients (14.88%). Lowering the threshold, the process vessels gradually dense, highly visible blood type, blood type rich in uterine leiomyomas uterine artery prior to arterial network developing the network, the general flow pattern, uterine leiomyomas artery network and uterine artery vascular network while developing, while in the non-rich blood type, uterine leiomyomas arterial vascular network developed after the uterus.[Conclusion]According to3D digitized model of uterine leiomyoma arterial network, The vascular supply and vascularity of uterine leiomyoma were analyzed before UAE. The vascular supply of uterine leiomyoma Type Ⅰ (unilateral predominant), type Ⅱ (bilateral balanced), type Ⅲ (single unilateral uterine artery) and type IV (single ovarian artery). The vascularity of uterine leiomyoma were divided into Extremely hypervascular type, hypervascular type, isovascular type and hypovascular. Inappropriate patients should be removed before UAE. Combined with the clinical efficacy of the different blood supply of the leiomyomas can be used to predict the efficacy after UAE. The model guides embolization agent distribution in the UAE and provides a new way for UAE standardized treatment.