| Over the past century, skin flap reconstruction has emerged as a preferred procedure to achieve soft tissue reconstruction. The recent development of perforator flaps, which provide adequate blood supply to reconstructed tissues and have significantly reduced donor site morbidity and functional loss, and enhanced the aesthetic outcome of the reconstructed recipient site, has made this approach very popular among plastic and reconstructive surgery and microvascular surgery. Despite the advances that have been made with perforator flaps, the surgical reconstruction procedure is still associated with occasional cases of incomplete revascularization due to poor pre-operative design and lack of knowledge about the vessels of donor and recipient site. These events result in severe necrosis and life-threatening immune responses, which can necessitate emergency amputation and affect the patient’s quality of life. Thus, surgeons face a critical challenge in how to carry out a detailed pre-operative evaluation of an individual perforator vessel, so as to best manipulate it to improve flap survival.Vascular morphology knowledge is the basis for plastic and microvascular operation. As early as1889, Calmanchot for the first time systematically described the originating cutaneous blood vessels and their territories on the2-D plane. In1936, Michel Salmon obtain substantially more detailed and clearer images of cutaneous vascular structures by using lead oxide-gelatin injections. In1986, Taylor further improved the technique;His definitive research in the field of originating arteries became known as "angiology" and was adopted widely as the "gold standard" in plastic surgery, so that it provided the foundation for the development and successful application of perforator flaps. With the rapid development of science and technology, cross-discipline, multi-disciplinary integration is the inevitable development of various disciplines and trends. Only relying on the traditional methods based on the anatomical dissection body has not objective, true and accurately display the individual blood flow characteristics of flap, can not meet modern clinical development. With high speed spiral CT, MRI and DSA data acquisition technology continues to progress and improvement, and a variety of corresponding dedicated imaging software development and application to various high-speed high-performance workstation,3-dimensional reconstruc-tion study on perforator vascular visualization of perforator flap has been gradually carried out, opened up new areas of vascular morphology from multi-planar, multi-angle, visualization, dynamic display of the three-dimensional anatomy of the flap. Lacking of adequate knowledge of perforator vascular morphology in the flap due to a late start, how to apply three-dimensional reconstruction technology to accurate quantification of the preoperative assessment of perforator vascular and then guide surgical incision, flap size, design the best surgical option has been become a new issues.While abroad, scholars have carried out applying three-dimensional CTA technology to preoperative appraising perforator vascular morphology, and confirmed that three-dimensional CTA technology for determining a location of a particular vessel is wearing a high-resolution, high sensitivity, high specificity of the new technology applied to the flap for the preoperative localization, but the technology is just started in recent years, the technology is continually being improved. Reviewing the existing relevant flap anatomical study of literature, there were lack of adequate understanding of morphology description of the perforator artery and location, pedicle length, axial, the blood area, and the anastomosis between adjacent blood vessels etc. Up to now, three-dimensional CTA can only locate where the perforator penetrates the adipofascial. It cannot determine the axiality of blood flow of the perforator after emerging from the muscle and the optimal perfusion territory in vivo. The research on the optimal perfusion area was also limited to specimens.As the variable and complex multidirectional flow pattern of perforator resulting from extensive vessels, great variation, difficult to location, and not easy to determine axial, there are some errors in perfusion size via three and four-dimensional CTA in specimens, comparing with that of surgical applications.With the development of interventional therapy, it expanded from a simple intervention to better treatment of nervous system vascular disease, heart diseases and movement disorders and other fields, and has made some successful experience. This topic,which based on combining the diagnosis of cerebrovascular disease with interventional therapy technology, investigated a new method of CTA using intrafemoral injection of contrast medium, instead of intravenous injection, to display the perfusion areas and the vascular anatomy of small perforators less than1.0mm in diameter in the lower extremities of live rabbits. The study makes the preoperative familiar with anatomical characteristics of individual perforator vascular, perfusion areas and blood flow characteristics as possible, to develop the best plastic surgery program, to design a more perfect preoperative planning, to provide a theoretical basis to achieve the true sense of the range of ideal blood supply transplantation in patients.Objective1. Explore the application of femoral artery cannulation technology in micro vascular imaging of perforator flap in vivo (live rabbit).2. Through the method of intrafemoral injection of contrast medium to explore the perforator mapping of three-dimensional reconstruction technology based CTA can clear, accurate and real reflection of perforator structure to quantitative research in vivo.3. Optimal perfusion areas of perforator vascular were quantitatively studied through four-dimensional reconstruction technology in vivo.4. Explore three and four-dimensional reconstruction technology based CTA whether can direct precise design of preoperative location and perforasome of perforator in vivo.Methods24New Zealand rabbits (16female,8male) weighing2.5-3.5kg were used. The rabbits were divided into two groups:anatomical experimental group (8rabbits) and CTA imaging group (16rabbits). In the anatomical group, the anatomy of the popliteal artery and its relation with adjacent structures were cleared by anatomic dissection in5rabbits. The perfusion zones of posterior thigh perforator were confirmed by microangiography in3rabbits. The remaining16rabbits were divided into two groups:first group of ten rabbits were divided into two equal groups (5rabbits, as experiment group, which underwent craniocaudal scanning by Siemens16-channel multidetector CT scanner after direct injection of iodine contrast through a microcatheter inserted into the femoral artery; another5rabbits, as control group, which underwent craniocaudal scanning by Siemens16-channel multidetector CT scanner after injection of iodine contrast through ear vein) to identify which administration method can clearly displayed the small perforator. Three-dimensional reconstruction images were recreated using maximum intensity projection (MIP) or the volume-rendering technique (VRT). The animals were evaluated daily for7days postoperatively, and behavior, hematoma, wound healing, inflammation, and suture loss were recorded. The second group of six rabbits went through the procedure twice:firstly, the animals were scanned as above mentioned, three and four-dimensional reconstructive images of the posterior thigh perforator were viewed using the dedicated workstation (AS128xCT), and then marked the location and perforasome size onto the posterior thigh skin base on the image data. Secondly, the perforator flap’s area measured with4D-CTA images was confirmed comparable to the microangiography data, and the results from the two methods were compared using statistical analysis.Results:Anatomical dissection showed that the posterior thigh perforator, which was consistently a musculocutaneous perforator, was always a single perforator artery supplying the posterior thigh skin. The diameters of the perforator artery and vein were0.3to0.4mm and0.4to0.5mm. The anatomical dissection confirmed the CTA mapping. All CTA images of the experimental group clearly showed that the posterior thigh perforators originated from the popliteal artery. Injection of contrast agent through the femoral artery, improved resolution of the CTA enabling perforator arteries with diameters in the range0.3-0.4mm to be visualized. However, the images of the control group indicated the course of the perforator in the muscle of only six legs (60%image). The images of remaining four legs did not display the perforator. The CTA-treated animals recovered without any complications. Four-dimensional CTA technique defined accurately and clearly location and perfusion territory of the perforators. The perforator flap’s area measured with4D-CTA images was confirmed comparable to the microangiography data, and the results from the two methods had no statistically significant difference.Conclusions:CTA using intra-arterial injection of contrast media enabled the visualization of small vessels less than1.0mm in diameter. This live animal model also showed the presence of vascular branches in the subdermis. The4D-CTA study accurately determined vascular territory and flow characteristics in vivo. The perforator location, axiality and perforasome study based on4D-CTA in animal model may help to advance preoperative design of perforator flaps for use in clinical practice and will be helpful for surgeons to achieve an optimal of perforator flap of lower limb in human patients. |
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