Adenomyosis is defined as a benign invasion of the endometrium into the myometrium resulting in diffuse enlargement of the uterus, which is manifested microscopically by the presence of ectopic non-neoplastic endometrial glands and interstitium in the myometrium, surrounded by hyperplastic smooth muscle. I. Clinical manifestations and pathological features of adenomyosis 80% of patients with pathological diagnosis of adenomyosis are 40-50 years old. Excessive menstrual bleeding is the most common clinical symptom of adenomyosis, with an incidence of about 50% [2], and other symptoms include dysmenorrhea, uterine bleeding and infertility. Other symptoms include dysmenorrhea, uterine bleeding and infertility. During gynecological examination, a diffusely enlarged and tender uterus with tenderness can often be detected. However, these symptoms and signs are nonspecific and can be seen in other diseases, such as nonfunctional uterine bleeding, uterine fibroids and ectopic endometriosis, making clinical diagnosis difficult, with a false-negative rate of 75% and a false-positive rate of 35% [3]. The diagnostic criteria for the pathology of adenomyosis are mainly based on the depth of endometrial invasion into the uterus, and the domestic diagnostic criteria for ectopic endometrium are at least 2 mm above the endometrial myometrial junction (approximately equivalent to a depth of 10´10 one field of view diameter by light microscopy at low magnification), but the diagnostic criteria in various foreign pathology textbooks vary, and the depth of endometrial invasion into the myometrium is diagnosed from 0.5 to 4.0 mm [4]. The literature reports the incidence of adenomyosis in all hysterectomy specimens ranging from 5% to 70% [4].A recent study by Mcclausland et al [5] showed that endometrial invasion of the myometrium to a depth of just over 1 mm with hyperplastic hypertrophy of smooth muscle cells can lead to dysmenorrhea. The pathogenesis of adenomyosis is still under investigation [6,7] and includes inhibition of cell adhesion by ligandin, increased expression of chorionic gonadotropin (HCG) and luteinizing hormone (LH) receptors, hyperestrogenemia and myometrial weakness. Weakness of the myometrium due to injury explains, in part, the history of hysterectomy, dilation, curettage, and multiple births that are common in patients with adenomyosis. Treatment of adenomyosis The main treatments for adenomyosis are as follows: 1. Drug therapy: Drug therapy is effective in controlling the patient’s symptoms, however, because patients are often combined with extra-uterine endometriosis, there is a lack of clinical control studies and effectiveness assessment is difficult. 2.Hysterectomy: Hysterectomy is the treatment of choice for patients with severe symptoms, no significant effect of drug therapy, and no fertility requirements. 3, conservative surgery: treatment options to preserve the uterus include endometrial resection, laparoscopic myeloablative electrocoagulation or excision, which Wood reported [8] to be effective in 50% of patients, but there are no long-term follow-up results. This type of treatment is usually used in patients with focal lesions. The extent of the lesion should be defined prior to treatment with this type of procedure. Removal of part of the myometrium reduces the volume of the uterine cavity at the time of pregnancy in postoperative patients, and there is a risk of miscarriage, preterm delivery, and uterine rupture [8]. Scar tissue may contain lesions that are not easily detected, and scarring may also prevent uterine bleeding affecting the early diagnosis of endometrial cancer [5].Cooperman [9] reported a case of occult endometrial adenocarcinoma after endometrial resection in a patient without functional uterine bleeding. III. Imaging diagnosis of uterine adenomyosis Imaging can clarify the diagnosis of uterine adenomyosis, assess the extent of lesions and the depth of myometrial invasion, and can monitor the condition after conservative surgical treatment, which is of great significance for the treatment of uterine adenomyosis. There are four main non-invasive imaging tests as follows 1. Hysterosalpingography HSG [4]: HSG is one of the early diagnostic methods for adenomyosis and is characterized by multiple needle-like shadows in the uterus, about 1-4 mm long, extending from the endometrium to the myometrium and ending in a cystic shape. The presence of adenomyosis is also indicated by localized aggregation of contrast in the myometrium in a honeycomb pattern. However, if the lesion does not communicate with the uterine cavity, it is difficult to diagnose and therefore less sensitive. In addition, if the contrast agent is not needle-like or honeycomb-like, it is not specific, so HSG has been replaced by other imaging methods. 2, Transabdominal sonography TAS [4]: TAS probe frequency is usually in 3.5~5.0MHz, which can comprehensively observe the uterus and its surrounding tissues and organs, with a longer imaging range and slightly poorer spatial resolution. The main manifestations of TAS in adenomyosis are irregularly sized cystic cavities of 5-7 mm with a honeycomb shape, loss of normal myometrial parenchymal echogenicity, hypoechogenicity of the myometrium, and an enlarged uterus with increased thickness of the posterior wall visible within the myometrium. However, these signs are non-specific, and it is difficult to diagnose adenomyosis based on these signs alone, and it is difficult to distinguish whether adenomyosis is combined with uterine fibroids by TAS, so the diagnostic value is limited. Transvaginal sonography TVS: TVS has made great progress compared with TAS. The 5.0-9.0MHz probe frequency has improved the spatial resolution and reduced the artifacts often found in transabdominal ultrasound. It is currently the initial and most commonly used diagnostic imaging method for patients with suspected adenomyosis. The literature reports [1] that TVS has a sensitivity of 80%-89%, a specificity of 50%-96%, and an overall accuracy of 68%-89%. The most common ultrasound signs of uterine adenomyosis are widened endometrial halo, interrupted continuity, uneven echogenicity of the myometrium, poorly defined hypoechoic areas, and small cyst-like echogenicity. The normal myometrium is divided into three layers in TVS: outer, middle and inner [4], the middle layer has the strongest moderate echogenicity among the three, the outer layer is richer in arcuate arteriovenous plexus and shows moderate to low echogenicity with a narrower range, the inner layer is mainly composed of longitudinal and circular smooth muscle fibers with lower echogenicity than the middle and outer layers, the inner layer is often referred to as the endometrial halo in sonograms, Kunz et al [11] reported that the endometrial halo in healthy women The width (unilateral) was (3.5+1.1) mm, and in patients with adenomyosis the width was (6.5+2.5) mm, where the mean width was (5.2+1.5) mm in patients aged <31 years and (6.8+2.5) mm in patients aged ³31 years, the exact pathological basis for thickening of the inner muscular layer is still unclear. The pathological basis of hypoechoic myofibrohypoplasia is smooth muscle hyperplasia around ectopic endothelial tissue [10], while inhomogeneous echogenic areas in the myofibrohypoplasia may be hyperechoic generated by ectopic endothelial tissue against a hypoechoic background of smooth muscle, which is small in most cases but occasionally exceeds 5 mm in diameter and presents as a hyperechoic nodule. Ectopic endometrial nodules are most often located within the inner myometrium and are occasionally seen extending from the endometrium into the myometrium in a finger-like or striated pattern, manifesting as an interrupted continuity of the endometrial halo, especially during the secretory phase of the menstrual cycle. Ectopic cystic glands dilated in the myometrium or vesicles formed by bleeding are the histopathological basis of small cysts in the myometrium of TVS, a sign present in about 50% of patients with adenomyosis, the lesions are usually 2-4 mm in diameter, as the basal layer is mostly unresponsive to hormonal changes and periodic bleeding is rare, but in rare cases ectopic endothelial bleeding can be extensive, leading to hematomas in the myometrium, called cystic adenomyosis [ 12]. In addition, there are several ultrasound signs such as uterine contour changes, occupancy effects and uterine enlargement, but the sensitivity and specificity of these signs in isolation for the diagnosis of adenomyosis is low [4]. Application of color Doppler ultrasound in TVS: In 1998 Chang et al [13] reported the use of color Doppler ultrasound in differentiating uterine fibroids from limited adenomyosis. It was shown that among all 78 patients with symptomatic and intrauterine nodules on ultrasound, 79% of limited adenomyosis and 82% of fibroids were detected using morphologic criteria; color Doppler ultrasound detected scattered arterial flow signals within the lesion in 88% of limited adenomyosis, whereas 87% of patients with fibroids showed peripheral flow signals around the lesion. The use of color Doppler ultrasound can help to more accurately differentiate uterine fibroids from limited adenomyosis. 4, magnetic resonance imaging MRI: MRI has high soft tissue resolution, image standardization, and repeatability. Some studies have shown that the sensitivity and specificity of MRI for the diagnosis of adenomyosis is 86% to 100%, and the total accuracy is 85% to 90%. [14,[15] MRI of uterine adenomyosis is characterized by diffuse or focal widening of the binding zone, focal high-signal areas within the binding zone on T2-weighted images, and linear streaks extending from the endometrium to the periphery. Normal pelvic MRI sagittal T2-weighted images clearly show the endometrial band structure and the low signal intensity band around the endometrium, called the Junctional zone (JZ). The width of the junctional zone varies widely in the normal population, ranging from 2 to 8 mm [16]. The width of the binding zone used by various authors to diagnose adenomyosis varies from 5 to 12 mm [1].Kang et al [17] found that 8 of 20 normal clinical volunteers with uterine MRI findings had at least one or more binding zone widths greater than 5 mm.A retrospective study by Reinhold [14] showed that if a binding zone width of 5 mm is used as a diagnostic criterion In a retrospective study by Reinhold [14], the sensitivity was 100%, but the specificity was only 31%, but the sensitivity was 93% and the specificity was 91% if 12 mm was used as the diagnostic criterion.Kang et al [17], in their clinical work, experienced that if the maximum band thickness was >12 mm, adenomyosis was highly suspected; if the band width was £8 mm, adenomyosis was basically excluded; and when the band The diagnosis of adenomyosis can also be made when the thickness of the band is between 8 and 12 mm, if there are other signs such as local widening of the band, unclear boundaries of the band, and focal high signal on T1 or T2-weighted images. It has been reported [18,19] that in 50-88% of patients with adenomyosis, focal high signal may be present in the low signal region on T2-weighted images, and the histopathological basis of such focal changes is ectopic endometrial glands, cystic dilated ectopic endometrial glands and their hemorrhagic remains. On T1-weighted images of MRI, ectopic endometrial glands have equal signal intensity to the surrounding myometrium and only occasionally show focal high signal corresponding to small areas of hemorrhage, making T2-weighted images of MRI more valuable for the diagnosis of adenomyosis. In some patients, T2-weighted images may show high-signal linear streaks extending from the endometrium to the myometrium. These streaks may represent direct invasion of the basal endometrium into the myometrium, and it has been reported [14] that T2-weighted images perpendicular to the long axis of the uterus are more useful for visualizing myometrial lesions and can be used as one of the routine examination cross-sections in patients with suspected adenomyosis. When ectopic endometrial glandular bleeding is more diffuse, adenomyosis evolves into the rarer cystic adenomyosis. MRI of cystic adenomyosis is characterized by a high-signal cystic lesion on T2-weighted images with a low-signal intensity area in the cystic wall. Adenomyosis lesions do not have an occupying effect on the endometrial or plasma surface, and the lesion contours are mostly oval, often distributed along the long axis of the uterus, with a clear demarcation between the normal and the myometrial layers of the lesion. However, it is worth noting that the MRI presentation of adenomyoma completely overlaps with that of uterine fibroids. However, the specificity of the diagnosis of TVS varies widely, probably due to the following reasons: the operator-dependent nature of ultrasonography, which varies greatly from operator to operator; the superiority of diagnosis based on real-time sonograms over stored static images; and the choice of study subjects, which can be attributed to the fact that the diagnosis of adenomyoma is based on a wide range of factors. The selection of study subjects, such as those with multiple cases of limited adenomyosis, is usually not as specific; the quality of diagnostic equipment is also relevant. Because of the low cost and high prevalence of TVS examination, TVS is the first choice for initial screening when clinical adenomyosis is suspected, and MRI can be selected to clarify the diagnosis in cases with atypical TVS lesions or those who decide to undergo conservative surgical treatment, and pre- and post-operative MRI comparisons are performed for patients treated with conservative surgery.