The uterus: in vitro MR-anatomic correlation of normal and abnormal specimens

Uterine junctional zone and adenomyosis: comparison of MRI, transvaginal ultrasound and histology

The uterine junctional zone is the subendometrial area in the myometrium that contributes to peristalsis and aids in spermatozoa and blastocyst transport. Alterations in the appearance of the junctional zone on transvaginal sonography (TVS) or magnetic resonance imaging (MRI) are associated with adenomyosis. The lack of standardization of description of its appearance and ill-defined boundaries on both histology and imaging hamper understanding of the junctional zone and limit its role in the diagnosis of adenomyosis. The objectives of this review were to investigate the accordance in definition of the junctional zone across different diagnostic approaches and to examine how imaging findings can be linked to histological findings in the context of diagnosis of adenomyosis. A comprehensive literature review was conducted of articles describing the appearance on imaging and the histological structure of the uterine junctional zone. Our review suggests that the junctional zone is distinguished from the middle and outer myometrium by gradual changes in smooth-muscle cell density, extracellular space, connective tissue, water content and vascular properties. However, while the signal intensity from the junctional zone to the middle myometrium changes abruptly on MRI, the histopathological changes are gradual and its border may be difficult or impossible to distinguish on two-dimensional TVS. Moreover, the thickness of the junctional zone measured on MRI is larger than that measured on TVS. Thus, these two imaging modalities reflect this zone differently. Although a thickened junctional zone is often used to diagnose adenomyosis on MRI, the presence of adenomyosis can be described more accurately as interruptions of the junctional zone by endometrial tissue, which leads to direct signs on imaging such as subendometrial lines and buds on two- and three-dimensional TVS or bright foci on MRI. The histopathological criteria for diagnosis are based on enlargement of the uterus with severe adenomyosis, and might not reflect its early stages. Clinicians should be aware that findings on MRI cannot be extrapolated readily to ultrasound. An understanding of this is necessary when investigating the uterine junctional zone as a functional unit and the association between visualization of direct features of adenomyosis in the junctional zone and clinical symptoms. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Cyclic changes in T2* relaxometry of human uterus during the menstrual cycle using BOLD MR imaging

PURPOSE

To evaluate dynamic changes of T2* values within the endometrium, junctional zone and myometrium during the menstrual cycle using blood oxygen level-dependent (BOLD) magnetic resonance imaging.

METHOD

Volunteers underwent MRI scans on menstrual phase, ovulatory phase and luteal phase, including T2-weighted imaging and BOLD MR imaging. Multi-gradient-recalled echo (MGRE) sequence was used to obtain BOLD MR images. T2* values of different uterine layers, including endometrium, junctional zone and myometrium, on sagittal images were analyzed quantitatively.

RESULTS

Twenty-four subjects calculated T2* values successfully. The T2* values of each zonal structure during menstruation were significantly lower than those during ovulatory phase (P < 0.05) and luteal phase (P < 0.001). The T2* value of junctional zone was significantly lower than that of the myometrium over all three menstrual phases (P = 0.000, menstrual; P = 0.000, ovulatory; P = 0.001, luteal). The mean T2* value in endometrium during the ovulatory phase was the highest of the uterine zones over menstrual cycle. During menstrual phase, there was no statistical difference between endometrium and junctional zone (P > 0.05). Conversely, the comparison of the T2* values between endometrium and myometrium, junctional zone and myometrium both showed significant difference (P = 0.000). The mean T2* values within endometrium during ovulatory phase and luteal phase were significantly higher than those within junctional zone and myometrium (P < 0.05).

CONCLUSIONS

Cyclic changes of T2* values in each zonal structure of the uterus were revealed during the menstrual cycle by means of BOLD technique, which may be potentially beneficial in investigating dysmenorrhea, guiding assisted reproductive technologies and monitoring hypoxia in gynecological tumors.

Classifying Adenomyosis: Progress and Challenges

Classically, the diagnosis of adenomyosis relied on histological examination of uteri following hysterectomy and classifications focused on the depth of endometrial invasion within the myometrium. There remain uncertainties around the cut-off point for the histological diagnosis. Imaging-based diagnosis enables recognition of the condition in women not undergoing surgery and facilitates the assessment of the extent of adenomyosis within the whole uterus, as well as of affections of the uterovesical pouch and of the pouch of Douglas. In this article, we explore the diagnostic uncertainties, the need to produce a classification of the condition and the challenges towards that goal. A distinction should be drawn between disease mapping and a classification that may link histological or image-based features with clinical characteristics, or with pathophysiology. An agreed system for reporting adenomyotic lesions may enable comparisons of research studies and thus contribute towards an informed classification. To this aim, we outline the features of the condition and explore the characteristics that are considered when producing a taxonomy. These include the latest proposal for subdivision of adenomyosis into an internal and an external variant. We also explore the uncertainties linked to classifying involvement of the uterovesical pouch, the pouch of Douglas and lesions in the outer myometrium. The limitations of currently available evidence suggest that agreement on a hypothesis to underpin a classification is unlikely at present. Therefore, current efforts will probably remain focused on disease mapping.

Diagnostic Accuracy of Transvaginal Ultrasound and Magnetic Resonance Imaging for Adenomyosis: Systematic Review and Meta-Analysis and Review of Sonographic Diagnostic Criteria

We aim to first systematically review and perform a meta-analysis of the diagnostic accuracy of transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI) and, second, to evaluate the accuracy of various sonographic diagnostic criteria for adenomyosis. A search of PubMed and Embase yielded 32 eligible studies. In diagnosing adenomyosis, the diagnostic performance of TVUS was found to be high and comparable to the performance of MRI. Of the eight sonographic criteria, only five were assessable. The best individual criterion was echogenic subendometrial lines and buds. Limited data exist for the various sonographic criteria, and further studies are required to compare their performance.

Perfusion of the uterine junctional zone in nulliparous and primiparous women assessed by DCE-MRI, as a function of menstrual cycle and hormonal contraception

PURPOSE

To evaluate the perfusion parameters of inner and outer myometrium in healthy nulliparous and primiparous women who are and who are not currently using hormonal contraceptives by means of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

MATERIAL AND METHODS

We performed pelvic 1.5T DCE-MRI on 98 women: 18 nulliparous non-users, 30 nulliparous users, 12 primiparous non-users and 38 primiparous users of hormonal contraception (mean age respectively 26.4, 25.8, 30.23 and 28.18years). The nulliparous non-users underwent DCE-MRI investigations during their follicular, ovulatory and luteal phase. Perfusion parameters (iAUC/volume, Ktrans, Kep and Ve) were assessed in the anterior and posterior junctional zone (JZ), outer myometrium and cervix.

RESULTS

In nulliparous non-users, the mean Ktrans and iAUC/volume showed a decrease from follicular to luteal phase (0.82 vs 0.55min^-1 for Ktrans, p=0/027 and 1.28 vs 0.68 for iAUC/volume, p<0.001). The anterior JZ demonstrated lower Ktrans (p=0.050) and higher Kep (p=0.012), in nulliparous non-users, lower Ktrans in nulliparous users (p<0.001) and lower Ve in primiparous users (p=0.012) than the anterior outer myometrium. Ktrans at the anterior and posterior JZ wall in nulliparous users was lower than in non-users (p=0.001 and p=0.013) and Ve at the anterior JZ wall in primiparous users was lower than in non-users (p=0.044).

CONCLUSION

This study provides data on normal perfusion parameters of inner and outer myometrium, which may be potentially useful in assisted reproductive therapy.

MR appearance of normal uterine endometrium considering menstrual cycle: differentiation with benign and malignant endometrial lesions

Background The thickness and signal intensity (SI) of normal uterine endometrium on T2-weighted (T2W) imaging changes depend on the menstrual cycle phase. Cases of normal endometrium that appear similar to endometrial lesions sometimes occur, and may result in misdiagnosis. Purpose To investigate normal endometrial appearance in luteal phase (LP) compared to that in follicular phase (FP), and to differentiate these appearances with those of endometrial lesions. Material and Methods Thirty-two normal volunteers prospectively underwent magnetic resonance (MR) examinations during LP and FP. Patients with pathologically confirmed endometrial polyps ( n = 9), hyperplasia ( n = 7), and cancer ( n = 15), who underwent MR examinations, were evaluated for comparison. Endometrial appearance was categorized into the following five types on sagittal T2W imaging and compared between LP, FP, and endometrial lesions: type 1, homogeneous higher SI; type 2, homogeneous iso SI; type 3, a bright midline and a peripheral iso SI layer; type 4, a lower/iso SI central line; and type 5, heterogeneous lower/iso SI. Endometrial thickness and SI were measured and also compared. Results Endometrial lesions were more frequently categorized as type 5 than normal endometrium ( P < 0.05). Endometrial thickness in LP (mean, 1.0 cm) was significantly greater than that in FP (0.6 cm), but not significantly different from polyps (1.1 cm), hyperplasia (1.0 cm), and cancer (0.9 cm). SI in FP was significantly higher than that in LP and that of all endometrial lesions. Conclusion Differentiation between normal endometrium in LP and endometrial lesions may be difficult based on thickness alone. Heterogeneous low SI may help to differentiate normal endometrium from endometrial lesions. Performing MR imaging during FP may also help due to higher SI of normal endometrium.

Staging in Local Endometrial Carcinoma

Possible deep (more than an inner third of the uterine wall) myometrial invasion and cervical extension of endometrial carcinoma were evaluated prospectively using magnetic resonance (MR) and transabdominal real-time sonography (US) in 20 and 10 patients, respectively. The data obtained from these examinations were compared with hysterosalpingography (HSG) and clinical modalities including hysteroscopy, sounding and histopathologic findings after surgery. The concordance of outlining cervical extension was between MR and hysteroscopy 85 per cent, and between US and hysteroscopy 50 per cent. Deep myometrial tumor invasion was suggested in 4/10 patients by US and in 6/20 by MR, and was confirmed in all but one in each group at histologic examination of the resected uterus. There were no false negative US or MR examinations. Transabdominal US did not prove accurate in defining local endometrial carcinoma (distinguishing between stages I and II), but it may be used as an additional tool in revealing myometrial invasion. MR, however, seems to refine the delineation of uterine tumor growth.

Uterine anatomy and function on cine magnetic resonance imaging

The female reproductive organ undergoes dynamic morphological changes under the influence of hormonal stimuli, and particularly those mediated by estrogen and progesterone. The uterus changes both its morphological appearance and its functional movements in function of these influences. Functionally, the uterus is known to exert two kinds of inherent contractility: sustained uterine contractions and uterine peristalsis. The former is focal and consists of the sporadic bulging of the myometrium, while the latter is rhythmic and manifests itself as the subtle stripping movement in the subendometrial myometrium. The mechanisms underlying these uterine movements, their relationship and their correlation to age, pharmaceutical administration, and a variety of gynecologic and obstetrical problems remain under discussion. Cine MR imaging may offer the potential to directly observe the changes undergone by the uterus in relation to important functions such as fertility and menstrual problems.

A Layer of Decreased Apparent Diffusion Coefficient at the Endometrial-Myometrial Junction in Uterine Adenomyosis

OBJECTIVES

To assess the detectability of a low-signal-intensity line within adenomyosis lesions adjacent to the endometrium on apparent diffusion coefficient (ADC) maps, and to establish correlations between these lesions and their possible causes, and more particularly the hormonal changes and magnetic resonance (MR) factors.

MATERIALS AND METHODS

MR images were obtained from 110 patients with adenomyosis (age 30-57 y.o.) using 3.0 T or 1.5 T MR units. Recognition of the low-signal-intensity line on ADC map was scored using confidence level. The correlation between recognition of the line and the following factors were examined: magnetic field strength, age group, menstrual cycle phases, history of delivery, and hormonal treatments. Presence of the structure corresponding to the low-signal-intensity line on ADC map was evaluated pathologically in the cases that underwent surgery.

RESULTS

The low-signal-intensity line visible on ADC map was recognized in 55/110 patients. The visibility of the line was not significantly related to hormonal status, age, history of delivery, or magnetic resonance imaging (MRI) magnet strength. There were no corresponding pathological structures.

CONCLUSION

One half of the adenomyosis patients showed discrepant appearances in T2-weighted (T2WI) vs. ADC map, but no significant relationship with hormonal changes was found in this study. This result may suggest that the low-signal-intensity line within the junctional zone may be related to a functional phenomenon.

Comparative analysis of changes in MR imaging of pre and post intrauterine progesterone implants in adenomyosis cases

BACKGROUND

Magnetic Resonance Imaging (MRI) plays an important role in the evaluation and management of adenomyosis. In this study, we first diagnosed the adenomyosis on MRI and then we analyzed the MRI changes in the uterus in pre and post intrauterine progesterone implants cases.

METHOD

All the patients with clinical diagnosis of menorrhagia or dysmenorrhea were screened by Ultrasonography (USG) of the pelvis. Patients with heterogeneous echo texture of the uterus were then evaluated by the MRI of the pelvis. All patients with MRI findings suggestive of adenomyosis formed the study group.

RESULT

On MRI study 60 patients were diagnosed as adenomyosis, 68.33% had diffuse adenomyosis and 31.66% had focal adenomyosis. 83% of diagnosed adenomyosis cases had high intensity signal foci which were seen in 75% cases of diffuse adenomyosis and 100% cases of focal adenomyosis. 50 diagnosed adenomyosis cases were then reviewed after 03 months, 06 months and 12 months to see for any change in the MRI findings in the post intrauterine implant cases. On follow up MRI after post progesterone intrauterine implant, 50% of the cases showed reduction in the high intensity signals, 10% of the cases showed mild reduction in the junctional zone thickness with no significant change in the uterine size.

CONCLUSIONS

It is inferred that MR imaging is not only helpful in diagnosing but also helpful in monitoring the effects of hormonal therapy in adenomyosis.

The history of MR imaging as seen through the pages of radiology

The first reports in Radiology pertaining to magnetic resonance (MR) imaging were published in 1980, 7 years after Paul Lauterbur pioneered the first MR images and 9 years after the first human computed tomographic images were obtained. Historical advances in the research and clinical applications of MR imaging very much parallel the remarkable advances in MR imaging technology. These advances can be roughly classified into hardware (eg, magnets, gradients, radiofrequency [RF] coils, RF transmitter and receiver, MR imaging-compatible biopsy devices) and imaging techniques (eg, pulse sequences, parallel imaging, and so forth). Image quality has been dramatically improved with the introduction of high-field-strength superconducting magnets, digital RF systems, and phased-array coils. Hybrid systems, such as MR/positron emission tomography (PET), combine the superb anatomic and functional imaging capabilities of MR imaging with the unsurpassed capability of PET to demonstrate tissue metabolism. Supported by the improvements in hardware, advances in pulse sequence design and image reconstruction techniques have spurred dramatic improvements in imaging speed and the capability for studying tissue function. In this historical review, the history of MR imaging technology and developing research and clinical applications, as seen through the pages of Radiology, will be considered.

Adenoma malignum detected on a trauma CT

Adenoma malignum is a rare subtype of cervical adenocarcinoma. Clinical presentation is variable with watery vaginal discharge being the most commonly associated finding. We report a case of adenoma malignum incidentally detected on pelvic computed tomography (CT) performed for a trauma patient. The cervical mass was further characterized by magnetic resonance (MR) imaging and remained compatible with adenoma malignum. Local cervical biopsy was suggestive of the diagnosis which was subsequently confirmed by gross surgical pathology. We briefly discuss adenoma malignum with particular attention to CT and MR imaging features.

Diseases of the female pelvis: advances in imaging evaluation

Magnetic resonance (MR) imaging has been widely accepted as a powerful imaging modality for the evaluation of the pelvis because of its intrinsic superior soft tissue contrast compared with that of computed tomography. In certain cases, however, the morphologic study provided by MR imaging may not be enough. Functional evaluation with perfusion and diffusion, which allow estimation of the microvascular characteristics and cellularity of the lesions, favors the differentiation of benign from malignant lesions. This article focuses on new magnetic resonance techniques and their contribution to the differentiation and characterization of pelvic pathologies.

T2* relaxometry mapping of the uterine zones

BACKGROUND

Previous literature demonstrated that the T2* value of the uterine junctional zone was lower than that of peripheral myometrium by using BOLD MR imaging. We expect T2* mapping image may add more information to T2-weighted images of the uterine myometrium.

PURPOSE

To evaluate whether T2* mapping software would reproduce the result of previous report, and to apply the software to benign uterine diseases.

MATERIAL AND METHODS

Five healthy volunteers and 19 patients clinically suspected of having benign pelvic disease were imaged using a 1.5T MR system. All women were of reproductive age, and all provided informed consent. Sagittal T2* images using a multishot EPI sequence were obtained. T2* values were calculated and color T2* maps reconstructed using a T2* fitting tool.

RESULTS

The uterine zones could be identified in all 24 examinations on the T2* maps. In addition, a thin "4th zone" was seen between the endometrium and the JZ (junctional zone) in 19 of 24 examinations. The T2* value of JZ was significantly lower than that of peripheral myometrium (PM) (P < 0.001). No significant difference in the T2* value of the JZ or of PM was noted between normal uterus and uterus with leiomyomas and/or adenomyosis.

CONCLUSION

A quantitative T2* map can easily be obtained using the PRIDE software T2* fitting tool, and the software reproduces the result from previous report. T2* value of the junctional zone was lower than that of peripheral myometrium regardless of having benign myometrial diseases.

Normal and variant pelvic anatomy on MRI

The superior tissue contrast and flexible imaging planes afforded by magnetic resonance imaging (MRI) versus competing technologies permit optimal depiction of the pelvic viscera. Targeted protocols developed for specific pelvic visceral organs highlight important anatomic features that may not be imaged by other modalities. Therefore, a solid understanding of normal and variant pelvic anatomy is crucial for appropriate interpretation of pelvic MRI studies. This article discusses the protocol strategies and relevant anatomy with commonly encountered anatomical variants in a segmented/organ-specific manner, using gender as a broad split given the substantial variance in relevant organs.

The enigmatic uterine junctional zone: the missing link between reproductive disorders and major obstetrical disorders?

While there is a growing realization that the origins of major obstetrical complications associated with defective deep placentation, such as pre-term labour, fetal growth restriction and pre-eclampsia, may lie in the very early pregnancy events, the underlying mechanisms are not understood. Impaired deep placentation is foremost a vascular pathology, characterized by a lack of endovascular trophoblast invasion and remodelling of a segment of the spiral arteries embedded within the inner myometrium of the uterus. Outside pregnancy, the inner myometrium represents a highly specialized, hormone-dependent structure, termed the junctional zone (JZ), which plays an integral part in the implantation process. The JZ changes with age and is disrupted in several reproductive disorders, such as endometriosis and adenomyosis, which in turn may account for the increased risk of adverse pregnancy outcome. Unlike the endometrium, the myometrial JZ is not readily accessible to biochemical or molecular studies, yet its structure and function can be assessed using imaging techniques, such as high-resolution ultrasound and magnetic resonance imaging. Thus, non-invasive assessment of the JZ prior to conception may turn out to be useful in identifying those women at risk of major obstetrical complications.

Uterine fibroid embolization imaging: interventionalist's perspective

Uterine fibroid embolization (UFE) is a minimally invasive and well-accepted form of treatment for patients with symptoms from fibroids. Imaging is routinely performed before the procedure for various reasons and after the procedure in cases with either complications or incomplete response to UFE. The interventionalists performing the procedure require specific information from these imaging studies. This article describes the imaging workup of patients referred for UFE, specifically the information from these imaging examinations before the procedure that are necessary to the interventionalist and the complications seen after the procedure.

MR Imaging of Benign Uterine Disease

MR provides excellent depiction of the female pelvic anatomy and has become the imaging modality of choice for the accurate diagnosis of numerous benign gynecologic conditions. Detection and characterization of leiomyomata and adenomyosis is performed routinely at many centers, and MR plays an important role in stratifying patients into appropriate treatment options. MR imaging is also uniquely well suited to the evaluation of gynecologic conditions that occur during pregnancy and in the postpartum period. This article describes MR protocols and the typical findings of various benign conditions of the uterine corpus and cervix, including congenital anomalies, leiomyomas, adenomyosis, and complications related to pregnancy.

Pelvic anatomy and MRI

An in-depth knowledge of the anatomy of the pelvis and pelvic sidewall is necessary before a gynaecologist can even contemplate making an initial examination and start management in cases of pelvic pathology or malignancy. This chapter provides basic information on gross pelvic anatomy structures that are of clinical relevance and discusses their correlation with medical imaging, especially magnetic resonance imaging (MRI). MRI is an ideal non-invasive technique in the assessment of normal anatomy and tissue characterization of pelvic pathology. The excellent soft-tissue contrast and the ability to direct multiplanar imaging and to demonstrate blood vessels without the use of intravenous contrast make MRI superior to other imaging modalities in the evaluation of pelvic abnormalities. The anatomical relation of the visceral organs, the differential zonal anatomy of the corpus uteri and the cyclical endometrial changes during the menstrual cycle are well depicted with MRI.

Uterine tissue development in healthy women during the normal menstrual cycle and investigations with magnetic resonance imaging

OBJECTIVE

High-resolution magnetic resonance imaging (MRI) was used to monitor both uterine endometrial and junctional zone morphometry during the normal menstrual cycle.

STUDY DESIGN

Twenty-four healthy, ovulating women were studied during a single menstrual cycle. Three scans were performed to prospectively coincide with the follicular, periovulatory, and luteal phases of the cycle.

RESULTS

MRI data showed a significant increase in endometrial and junctional zone volume, between the follicular and periovulatory phases, with a significant decrease in endometrial volume observed from the periovulatory to luteal phases. The regularity index, which is a novel subjective assessment of junctional zone structure, varied significantly and demonstrated a less regular junctional zone in the luteal phase.

CONCLUSION

This study has quantified the normal developmental changes of uterine tissue during the menstrual cycle with MRI. Junctional zone data from MRI may play a major role in future studies that investigate menstrual disorders, subfertility, and pathologic changes.

Uterine peristalsis shown on cine MR imaging using ultrafast sequence

PURPOSE

To demonstrate and evaluate uterine peristalsis on cine magnetic resonance imaging (MRI) using ultrafast imaging.

MATERIALS AND METHODS

Serial MR uterine images (300) were obtained from 15 normal volunteers over four menstrual phases using true fast imaging with steady-state precession (true FISP) technique over 117 seconds and videotaped. Three radiologists independently evaluated videotapes of 59 studies. Uterine peristalsis was defined as wavy movements of subendometrial myometrium or endometrium. Interobserver reliability was evaluated using a Kappa coefficient. Fifty-four studies obtained in appropriate phases were analyzed.

RESULTS

Cine MRI displayed uterine peristalsis in 30 of 59 studies; consensus reading showed direction in 23 studies. Reliability between the final consensus of the recognition of uterine peristalsis and those of the three readers was extremely concordant, with a Kappa coefficient of 0.908. Wave direction was cervico-fundal in follicular and periovulatory phases, with frequency of contraction waves being 1.2-2.3 per minute in positive studies.

CONCLUSION

Uterine peristalsis was demonstrated on cine MR using ultrafast MRI. Direction and frequency of peristaltic waves are closely related to menstrual cycle phases. Supplementary material for this article can be found on the JMRI website at http://www.interscience.wiley.com/jpages/1053-1807/suppmat/index.html.

Myometrial hyperplasia in pediatric, adolescent, and young adult uteri

OBJECTIVES

To evaluate if myometrial hyperplasia is a congenital variation in myometrial differentiation, or an acquired structural disorder of the myometrium, this study evaluated whether myometrial hyperplasia was present in uteri of children, adolescents, and young adults.

METHODS

We studied 19 pediatric/young adult uteri in cases with no clinical history of uterine disease. Random photomicrographs at 100x, taken at 1, 5, and 10 mm beneath the endometrium, were assessed for increased cellularity and nucleus/cell ratio, as compared to normal myometrium in the outer third of the same uterus.

RESULTS

Myometrial hyperplasia was generally absent in prepubertal uteri, first appeared in adolescent uteri just beneath the endometrium, and was found at 5 mm depth only after age 18. It decreased with depth beneath the endometrium (P<0.05).

CONCLUSIONS

Myometrial hyperplasia is not a congenital anatomic variation in myometrial differentiation, but rather an age-related acquired structural variation. Its relationship to common adolescent symptoms of dysmenorrhea and anovulatory bleeding remains unknown and unexplored.

Adenomyosis

Adenomyosis is characterized as ectopic endometrial tissues within the myometrium in the uterus. The etiology and pathogenetic mechanism(s) responsible for adenomyosis are poorly understood. Definite diagnosis is made on hysterectomy specimens, although attempts are made at securing preoperative diagnosis by magnetic resonance imaging and myometrial biopsies. Definite treatment of symptomatic women is hysterectomy.

Anatomy and physiology of the female pelvis: MR imaging revisited

This article reviews the normal anatomy of the female pelvis and focuses on uterine physiology, presenting the kinematics of the uterus that can be identified on ultra-fast MR imaging. It also discusses the many facets of the junctional zone on MR imaging. Ultra-fast MR imaging seems to be a powerful tool for evaluating normal anatomy, physiology, and pathology of the uterus. J. Magn. Reson. Imaging 2001;13:842-849.

Endometrial-myometrial interface: relationship to adenomyosis and changes in pregnancy

The endometrial-myometrial interface (EMI) is an important region of the human uterus, which has attracted little research attention. This mucosal-muscular interface has characteristic features when compared with other similar interfaces in the human body. It lacks an intervening tissue layer and as a result, the endometrium sits directly on the myometrium rendering it vulnerable to invasion by the endometrium. Both endometrium and myometrium are sensitive to sex steroids, and their structure and function depend to a large extent on the sex hormonal milieu. Endometrium, which forms one border of the EMI, is a complex tissue consisting of several polarized microenvironments. At a cellular level, sex steroids interact with local mediators secreted by a variety of cell types and are important in maintaining the complex structure and function of the endometrium. Basal endometrium contains prominent aggregates of leukocytes that may be important in controlling local cell growth and function. Myometrium also has a distinct zonal anatomy. The recently described junctional zone differs structurally and functionally from the outer myometrium, although these functions are not yet clearly understood. Embryologically, it originates from müllerian ducts together with endometrium, whereas the outer myometrium has a non-müllerian origin. During early pregnancy, the EMI is disturbed by invading trophoblast. Alterations of myometrial intercellular matrix proteins together with expression of appropriate receptors by the trophoblast seem to regulate this unique interaction. The EMI also is disrupted in adenomyosis. The sequence of events taking place at the EMI during development of this pathology is still debated.

Structural abnormalities of the uterine wall in women with endometriosis and infertility visualized by vaginal sonography and magnetic resonance imaging

In women with endometriosis, the peristaltic activity of the uterus is significantly enhanced and may even become dysperistaltic at midcycle. Since uterine peristalsis is confined to the endometrium and the subendometrial myometrium with its predominantly circular arrangement of muscular fibres it was assumed that this dysfunction might be associated with structural abnormalities that could be visualized by high resolution ultrasonography and magnetic resonance imaging (MRI). Therefore, the uteri of women with and without endometriosis were subjected to endovaginal sonography (EVS) and to MRI. In EVS, women with laparoscopically proven endometriosis and infertility exhibited an infiltrative expansion of the archimetra in that the halo surrounding the uterine endometrium and representing the subendometrial myometrium was significantly enlarged compared with controls. The expansion was more pronounced in older than in younger women. There was, however, no relationship between the width of the expansion and the severity of the endometriotic disease. Similar data were obtained by MRI in that the 'junctional zone' in women with endometriosis and infertility was expanded in comparison with controls. The results of this study provide further support to the notion that endometriosis is primarily a uterine disease.

Diffuse and focal adenomyosis: MR imaging findings

Adenomyosis is a common gynecologic disorder that affects women during their menstrual life. Preoperative magnetic resonance (MR) images obtained in 45 patients with pathologically proved adenomyosis who underwent hysterectomy were retrospectively reviewed. Diffuse adenomyosis was seen in 30 cases (66.7%) and focal adenomyosis in 15 cases (33.3%). On T2-weighted MR images, diffuse adenomyosis usually manifested as diffuse thickening of the endometrial-myometrial junctional zone (7-37 mm; mean, 16 mm) with homogeneous low signal intensity. T2-weighted MR images were superior to contrast material-enhanced T1-weighted images in the evaluation of junctional zone thickening. High-signal-intensity foci were observed on T2-weighted images only in nine cases and on both T1- and T2-weighted images in three cases. Focal adenomyosis manifested on both T2-weighted and contrast-enhanced T1-weighted MR images as a localized, low-signal-intensity round or oval mass with a diameter of 2-7 cm (mean, 3.8 cm). All but one of the focal lesions had ill-defined margins. High-signal-intensity foci were noted in all cases of focal adenomyosis, either on T2-weighted images only (four cases) or on both T1- and T2-weighted images (11 cases). MR imaging is useful in diagnosing adenomyosis, differentiating adenomyosis from uterine myoma, and planning appropriate treatment.

Uterine adenomyosis: current concepts in imaging

This article reviews the clinical findings, histopathological features, and treatment options of uterine adenomyosis and relates them to the role of the radiologist in evaluating patients with this disease. Knowledge of the histopathology of this disease is essential to understanding the range of imaging findings encountered in patients with uterine adenomyosis. In addition, the imaging features and accuracy of noninvasive diagnostic modalities that have proven useful in diagnosing adenomyosis will be discussed. Correctly diagnosing the presence of adenomyosis, and determining its extent, is crucial in planning the appropriate type of therapy.

Tissue characterization in the female pelvis by means of MR imaging

Pelvic imaging techniques such as computed tomography and ultrasonography provide a limited capability for tissue characterization. Fat, fluid, and calcification, for example, can be identified on the basis of parameters such as x-ray attenuation, echogenicity, and sound attenuation. Because of the many tissue parameters, such as T1, T2, magnetic susceptibility, and chemical shift, that contribute to signal intensity, magnetic resonance (MR) imaging may afford an ability to identify a wider array of specific tissues. The purpose of this article is to review the ability of MR imaging to help identify various types of soft tissue and to provide an approach to interpretation of MR images of the female pelvis through tissue characterization. Lipid, fluid, hemorrhage, smooth muscle, fibrosis, solid malignant tissue, and hydrated soft tissue (including edema, mucin, and myxomatous tissue) have typical MR imaging properties, and their presence in a mass can often be established on MR images. Consideration of the tissue composition of various pathologic processes in the pelvis can result in more systematic approaches to image interpretation and thus narrow the differential diagnosis.