## 1 Introduction  
Ganglion cysts are common benign soft tissue tumors that are primarily encountered in the wrist. A history of trauma is elicited in at least 10% of cases and is considered a causative factor, although the pathogenesis remains unclear [1]. Patients with ganglion cysts may not feel pain, but appropriate treatment is required when the patient feels stiffness or experiences interference with the movement of their joints, and a high recurrence rate is reported even after surgical or non-surgical treatment [2]. Upon examination, the cystic structures of wrist ganglion cysts are usually 1-2 cm in size [3]. Statistically, more than half of wrist ganglion cysts are found in the dorsal component of the scapholunate ligament, but they can also be found in several other sites across the dorsal aspect of the wrist capsule [1, 3]. Microscopically, the pedicle contains a tortuous lumen, connecting the cyst to the underlying joint [4]. Moreover, the presence of a daughter cyst of a preliminary ganglion arising around the joint capsule is often seen. Usually, it can be easily diagnosed by clinical features or location, but it can also be clinically confused with other masses if it is accompanied by complications or when it occurs at an unusual site [5]. The ganglion adjacent to the radial artery near the radiocarbon joint may be pulsatile and that may cause a possible clinical misidentification as a pseudoaneurys [6]. There are non-surgical and surgical options for treating a ganglion cyst. Nonsurgical treatments of ganglion, including aspiration, steroid injection sclerotherapy, and hyaluron, are generally ineffective, although they do have lower complication rates. Open surgical excursions have a lower recurrence rate, but they have higher complication rates and longer recovery periods [7, 8]. The recurrence rate can be reduced when the pedicle of the ganglion is completely removed during surgery [8]. Therefore, it is helpful to plan surgery to accurately identify the location of the pedicle during imaging. Ultrasonography is, in general, an effective imaging method for evaluating a palpable soft tissue abnormality, for it has a strong ability to differentiate a solid mass from a cyst. Insoft tissue lesions, the locations are epidermis, dermis, subcutaneous fat layer, and muscle layer. It is important to recognize the exact location of the ganglion, as well as daughter cysts and the pedicle, before surgery [2]. In the treatment phase, ultrasonography also provides guidance for aspiration and injection [3; 9], as well as information regarding the exact location of the pedicle for surgery [8]. The most common reason for ganglion recurrence after surgery is that the pedicle connected to the joint is not completely removed [10]. However, the common complaint about using ultrasonography in diagnosis is its operator subjectivity in that the correctness of sonographic image analysis is largely dependent on the quality of the equipment and the operators' expertise [10]. For example, beginners easily misdiagnose the exact location of the ganglion and overlook the presence of the pedicle. To avoid such subjectivity, we need an automatic image segmentation and identification tool for anatomical landmarks in the image analysis [11]. It is a difficult problem since the input image may not have sufficient contrast between target object and the background or it contains speckle noise, which is an inherent property of ultrasound imaging modality [12]. In this paper, we propose an efficient automatic segmentation method with carefully designed contrast enhancement by fuzzy stretching. Only surgically confirmed ganglion cysts were included in this study. The purpose of this study is to determine the extent of the ganglion cysts, as well as the daughter cysts, and to find the pedicle accurately and automatically within the ultrasound image using an intelligent pixel clustering method. Unfortunately, there is no directly comparable research in this field other than our previous attempts.