Encyclopedia of endometriosis: a pictorial rad-path review

Endometriosis affects approximately 10% of reproductive age women and represents a significant cause of pelvic pain and infertility. Unfortunately, the diagnosis of endometriosis is often delayed by years. Endometriosis may manifest as cystic lesions in the ovaries known as endometriomas. Superficial endometriosis is typically detected by laparoscopy along the pelvic peritoneum as these lesions tend to be difficult to detect by imaging. Deep infiltrative endometriosis may be detected by ultrasound, CT or MRI in classic locations within the pelvis, such as the posterior cul-de-sac and uterosacral ligaments. Endometriosis may also involve the thorax, gastrointestinal and urinary tracts, and locations such as the abdominal wall and abdominal organs. We present MRI and CT case examples, together with corresponding laparoscopic and histopathology images to enhance radiologists' understanding of this disease.

What abdominal radiologists should know about extragenital endometriosis-associated neuropathy

PURPOSE

The aim of this study is to provide an overview of endometriosis-associated neuropathy and to review main anatomical concepts of intrapelvic peripheral nerves.

METHODS

In this pictorial essay, we review the anatomy of pelvic nerves and imaging features of endometriosis-associated neuropathy. We also evaluate clinical findings, imaging features, and outcome of seven patients with endometriosis-associated neuropathy.

RESULTS

Nerve involvement by endometriosis is rare and may manifest with neurological symptoms, including pain, muscle weakness, bowel and bladder incontinence, and paraplegia. The neural involvement may be isolated or caused by a direct extension of a deep infiltrating endometriosis of the pelvic structure. Magnetic resonance imaging (MRI) is a reliable imaging modality for detecting neural involvement of endometriosis. On MRI, the main imaging features are retractile fibrous tissue and endometriomas. The signal intensity of the endometriotic tissue may vary depending on the age of the hemorrhage and the proportion of endometrial cells and stroma. Early diagnosis and treatment may avoid permanent neural damage.

CONCLUSION

Considering that patients with endometriosis usually undergo pelvic MRI, which is generally reported by a non-musculoskeletal-trained radiologist, abdominal radiologists need to be familiar with the pelvic nerve anatomy and the possible patterns of presentation of neural endometriosis. Early diagnosis may obviate permanent nerve damage and MRI is a reliable tool for the diagnosis.

Hysterosalpingography in endometriosis: performance and interpretation

Endometriosis is often seen and sometimes initially diagnosed on hysterosalpingography (HSG), an imaging exam routinely performed on patients with infertility. Here we discuss the role of HSG in the evaluation of patients with infertility with a focus on patients with endometriosis. The HSG technique, including patient preparation as well as potential risks and complications, is detailed. Imaging findings in patients with endometriosis are illustrated and a template for exam reporting is presented. Common imaging pitfalls are described with examples.

Endometriosis MRI lexicon: consensus statement from the society of abdominal radiology endometriosis disease-focused panel

Endometriosis is a common gynecologic disorder characterized by the presence of ectopic endometrial tissue outside the endometrial cavity. Magnetic Resonance Imaging (MRI) has become a mainstay for diagnosis and staging of this disease. In the literature, significant heterogeneity exists in the descriptions of imaging findings and anatomic sites of involvement. The Society of Abdominal Radiology's Endometriosis Disease-Focused Panel presents this consensus document to establish an MRI lexicon for endometriosis MRI evaluation and anatomic localization.

Understanding malignant transformation of endometriosis: imaging features with pathologic correlation

PURPOSE

Transformation of benign endometriosis to endometriosis-associated ovarian carcinoma (EAOC) is rare; however, women with endometriosis are four times more likely to develop EAOC which can present 20 years earlier than de novo ovarian cancer. Presenting symptoms are often vague and the radiologist's role in recognizing EAOC is critical for early detection and treatment. Histopathologic evaluation remains the mainstay for definitive diagnosis.

METHODS

Using a case-based approach, this article will review the sonographic, CT, and MRI features of EAOC with an emphasis on MRI. Histopathologic correlation of benign and malignant endometriosis will be reviewed.

RESULTS

Multiple factors contribute to the malignant transformation of endometriosis including genetic alterations, hormonal influences, oxidative stress, and inflammation. Malignancy most often occurs in ovarian endometriomas with less common sites involving the rectovaginal septum, rectosigmoid colon, and abdominal wall scars. The most common pathologic subtypes are endometrioid adenocarcinoma and clear cell carcinoma. MRI is the most specific imaging modality for evaluating EAOC. Key MR features include solid enhancing nodules (accentuated by subtraction imaging), nodular septations, loss of T2 shading within the endometrioma, and diffusion restriction.

CONCLUSIONS

EAOC is a distinct disease that affects women with benign endometriosis at younger ages than classic ovarian cancer. Understanding the imaging features of malignant transformation of endometriosis is essential for early diagnosis and timely definitive treatment.

Imaging of gastrointestinal endometriosis: what the radiologist should know

Deep invasive gastrointestinal endometriosis (DIGIE) is a frequent and severe presentation of endometriosis. Although most cases invade the rectosigmoid colon, DIGIE can involve any portion of the gastrointestinal tract from the stomach to the rectum, and is commonly multifocal and multicentric. Although histopathologic confirmation with surgery remains the gold standard for diagnosis, ultrasound (US) and magnetic resonance imaging (MRI) are the key non-invasive imaging modalities for initial assessment. US may be preferred as a screening study because of its easy availability and low-cost. Pelvic MRI and magnetic resonance enterography (MRE) provide substantial advantages for disease mapping in the pre-operative period, particularly in extensive bowel endometriosis. Although medical management of DIGIE with hormonal therapy can help control symptoms, disease course can be relentless and require surgical intervention. Surgical options depend on, the location; length; depth; circumference; multicentric or multifocal disease. With procedures including simple excision, fulguration of superficial lesions, shaving, disc excision, and segmental resection. A successful treatment outcome is largely dependent on good communication between the treating surgeon and the radiologist, who can provide vital information for effective surgical planning by reporting the key elements that we elaborate upon in this paper.

Endometriosis in pregnancy

Endometriosis constitutes the presence of ectopic endometrial glands and stroma outside the uterine endometrium, which is hormonally responsive and responds to pregnancy hormones as well. Decidualization is a physiologic process, where the normal endometrium readies itself for optimal accommodation of a pregnancy. A similar hormonal response can be seen with ectopic endometrium as well. As such, ovarian endometriomas and deep endometriosis implants can undergo decidualization. Overall, the progestational state of pregnancy favors an improvement in endometriosis, however, decidualization can lead to findings that can lead to increased size of endometriomas and deep infiltrative endometriosis implants, changes in imaging appearance and even complications, such as spontaneous hemoperitoneum in pregnancy. Awareness of this process can help prevent misdiagnosis of decidualized endometriomas as ovarian malignancy and recognize common imaging manifestations of hormonal effects of pregnancy on endometriosis.

MR findings for differentiating decidualized endometriomas from seromucinous borderline tumors of the ovary

PURPOSE

Decidualized endometriomas (DEs) and seromucinous borderline tumors (SMBTs) exhibit similar MR findings including markedly hyperintense mural nodules within endometriotic cysts on T2-weighted images. The present study aimed to assess the efficacy of MR imaging for differentiating between DEs and SMBTs of the ovary.

MATERIALS AND METHODS

MR images of 8 DEs and 14 SMBTs were retrospectively assessed and compared according to pathologies.

RESULTS

With regard to quantitative assessments of mural nodules, the number and signal intensity ratios (SIRs) on T1-weighted images were significantly greater in DEs than in SMBTs (11.0 ± 8.4 vs. 4.3 ± 4.1, p < 0.05 and 2.36 ± 0.56 vs. 1.49 ± 0.27, p < 0.01, respectively), whereas the height was significantly lower in DEs than in SMBTs (4.5 ± 1.4 mm vs. 21.9 ± 11.4 mm, p < 0.01). However, there were no significant differences between DEs and SMBTs in the SIRs on T2-weighted images, SIRs on diffusion-weighted images, and apparent diffusion coefficient values. With regard to qualitative assessments of mural nodules, the lobulated margin, pedunculated configuration, and T2 hypointense core were significantly more frequent in SMBTs than in DEs (71% vs. 0%, p < 0.01; 86% vs. 0%, p < 0.01; and 43% vs. 0%, p < 0.05, respectively).

CONCLUSION

The number, height, SIRs on T1-weighted images, lobulated margin, pedunculated configuration, and T2 hypointense core of mural nodules within endometriotic cysts were useful MR findings for differentiating DEs from SMBTs.

Robotic treatment for urinary tract endometriosis: preliminary results and surgical details in a high-volume single-Institutional cohort study

BACKGROUND

Aim of the study was to present the surgical techniques and the postoperative outcomes in women treated with robotic excision for deep endometriosis involving the urinary tract.

MATERIALS AND METHODS

We retrospectively reviewed the prospectively recorded clinical data of women consecutively undergoing minimally invasive treatment for complex endometriosis involving urinary tract in our center between January 2012 and June 2018. All the patients received a preoperative multidisciplinary evaluation with the general surgeon, the gynecologist and the urologist due to the frequent concomitant involvement of bowel and genital system. Patients undergoing robotic surgery were treated with the Si or Xi da Vinci surgical system.

RESULTS

A total of 74 consecutive patients were enrolled. Twenty-eight (37.8%) patients underwent conventional laparoscopy and 46 (62.2%) robotic surgery. Only patients treated with robotic approach were considered for the final analyses. Overall, 17 (36.9%) patients were treated with partial cystectomy, 13 (28.3%) with ureteral reimplantation, 10 (21.7%) patients were treated with ureteral lysis, 4 (8.7%) with removal of bladder endometrial node without opening the mucosa layer and 2 (4.3%) with ureteral end-to-end anastomosis. Concomitant involvement of bowel and genital system was registered in 14 (30.4%) and 32 (69.5%) patients, respectively. No conversions to laparotomy were recorded. Overall, 5 (10.9%) patients experienced postoperative complications, of which only one was a major complication (Clavien 3b). At a median follow-up of 31.3 (IQR 17.6-43.3) months, 4 (8.7%) patients experienced disease recurrence at the level of urinary tract.

CONCLUSIONS

Robotic excision of urological endometriosis represents a safe and effective treatment option, since a limited rate of surgical complications was recorded even in cases of multi-organ disease.

Imaging of Benign Adnexal Disease

This article provides an overview of the imaging evaluation of benign ovarian and adnexal masses in premenopausal and postmenopausal women and lesions discovered during pregnancy. Current imaging techniques are discussed, including pitfalls and differential diagnosis when necessary, as well as management. It also reviews the now well-established American College of Radiology (ACR)/Society of Radiologists in Ultrasound consensus guidelines and covers the more recently introduced Ovarian-Adnexal Reporting and Data System by the ACR and the recently published ADNEx Scoring System.

Niche role of MRI in the evaluation of female infertility

Infertility is a major social and clinical problem affecting 13-15% of couples worldwide. The pelvic causes of female infertility are categorized as ovarian disorders, tubal, peritubal disorders, and uterine disorders. Appropriate selection of an imaging modality is essential to accurately diagnose the aetiology of infertlity, since the imaging diagnosis directs the appropriate treatment to be instituted. Imaging evaluation begins with hystero- salpingography (HSG), to evaluate fallopian tube patency. Uterine filling defects and contour abnormalities may be discovered at HSG but usually require further characterization with pelvic ultrasound (US), sono-hysterography (syn: hystero-sonography/saline infusion sonography) or pelvic magnetic resonance imaging (MRI), when US remains inconclusive. The major limitation of hysterographic US, is its inability to visualize extraluminal pathologies, which are better evaluated by pelvic US and MRI. Although pelvic US is a valuable modality in diagnosing entities comprising the garden variety, however, extensive pelvic inflammatory disease, complex tubo-ovarian pathologies, deep-seated endometriosis deposits with its related complications, Mulllerian duct anomalies, uterine synechiae and adenomyosis, often remain unresolved by both transabdominal and transvaginal US. Thus, MRI comes to the rescue and has a niche role in resolving complex adnexal masses, endometriosis, and Mullerian duct anomalies with greater ease. This is a review, based on the authors' experience at tertiary care teaching hospitals and aims to provide an imaging approach towards the abnormalities which are not definitively diagnosed by ultrasound alone.

Beyond adenocarcinoma: MRI of uncommon rectal neoplasms and mimickers

OBJECTIVE

To provide a review of rare rectal tumors beyond adenocarcinoma.

RESULTS

Rectal cancer is a common malignancy, both in the United States and abroad. In addition to adenocarcinoma, abdominal radiologists will encounter a variety of other less common rectal masses, both benign and malignant neoplasms as well as non-neoplastic mimickers. Familiarity with these conditions and their characteristic features on MRI is useful in clinical practice. In this article, a number of such conditions are discussed, with an emphasis on distinguishing features on MRI of the rectum.

CONCLUSION

Familiarity with the MRI features of rare rectal tumors beyond adenocarcinoma, as well as a small number of non-neoplastic mimics, is important for abdominal imagers to make diagnostic differentials and to assist in treatment planning.

Magnetic resonance imaging presentation of deep infiltrating endometriosis nodules before and after pregnancy: A case series

OBJECTIVE

To compare the magnetic resonance imaging (MRI) features of deep infiltrating endometriosis (DIE) lesions before and after pregnancy.

DESIGN

Retrospective study.

SETTING

A single French university tertiary referral hospital.

PATIENTS

Twenty-one women without a prior history of surgery for endometriosis with a radiological diagnosis by MRI with two sets of examinations performed before and after pregnancy.

INTERVENTIONS

The volumes of the lesions were compared using the same protocol before and after pregnancy based on MRI (1.5 T) examinations by a single experienced radiologist who is a referring practitioner for image-based diagnosis of endometriosis.

MAIN OUTCOME MEASURE(S)

The DIE lesion volume.

MEASUREMENTS AND MAIN RESULTS

Between October 2012 and December 2016, a total of 21 patients (67 lesions) were included and compared before and after pregnancy. The mean time interval between the MRI before pregnancy and delivery was 19.6 ± 8.5 months (median: 17.6, IQR 13.5-25.2 months). The mean time interval between delivery and the MRI after pregnancy was 11.0 ± 6.4 months (median: 8.3, IQR 6-15.2 months). The mean overall DIE lesion volume by MRI was significantly higher before pregnancy compared to after pregnancy (2,552 ± 3,315 mm3 vs. 1,708 ± 3,266 mm3, respectively, p < 0.01). The mean volume by MRI of the largest lesion of each patient was significantly higher before pregnancy compared to after pregnancy (4,728 ± 4,776 mm3 vs. 3165 ± 5299 mm3; p < 0.01).

CONCLUSION

Our data indicate a favorable impact of pregnancy on DIE lesion volumes as measured by MRI.

Suspensory Ligaments of the Female Genital Organs: MRI Evaluation with Intraoperative Correlation

The uterus, which plays an important role in the reproductive process, provides a home for the developing fetus and so must be in a stable, though flexible, location. Various structures with suspensory ligaments help provide this berth. MRI with high spatial resolution allows us to detect and evaluate these relatively fine structures. Under physiologic conditions, MRI can be used to depict uterine and ovarian ligaments (ie, the uterosacral, cardinal, and round ligaments, as well as the suspensory ligament of the ovary). In the presence of pathologic conditions (inflammation, endometriosis, tumors), the suspensory ligaments may appear thickened or invaded, which makes their delineation easier. Understanding the normal anatomy of the suspensory ligaments of the female genital organs and using a standardized nomenclature are essential for identifying and reporting related pathologic conditions. The female pelvic anatomy and the suspensory ligaments of the female genital organs are described as depicted with MRI. Also, the compartmental anatomy of the female pelvis is explained, including the extraperitoneal pelvic spaces. Finally, a checklist is provided for structured reporting of the MRI findings in the female pelvis. Online supplemental material is available for this article. ^©RSNA, 2018.

Diagnostic performance of computed tomography for bowel endometriosis: A systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis regarding the performance of CT for diagnosis of bowel endometriosis.

MATERIALS AND METHODS

Pubmed and EMBASE were systematically searched up to March 28, 2019. Diagnostic accuracy studies using CT for diagnosis of bowel endometriosis using laparoscopy followed by histopathology as the reference standard were included. Methodological quality of the included studies was evaluated using Quality Assessment of Diagnostic Accuracy Studies-2. Sensitivity and specificity were pooled using hierarchical summary receiver operating modelling. Meta-regression analysis was done to explore heterogeneity.

RESULTS

Twelve studies (1091 patients) were included. Pooled sensitivity and specificity were 0.92 (95% confidence interval [CI], 0.83-0.97) and 0.95 (95% CI, 0.88-0.98), respectively. Substantial heterogeneity was present: I² = 92.38% for sensitivity and 89.09% for specificity. Deeks' asymmetry test suggested publication bias (p = 0.04). At meta-regression analysis, history of prior surgery for endometriosis was the only significant factor affecting heterogeneity (p < 0.01). Specifically, studies that included patients with such history demonstrated significantly greater specificity than studies that did not (0.95 [95% CI, 0.91-1.00] vs 0.75 [95% CI, 0.43-1.00]).

CONCLUSIONS

CT shows excellent performance in the diagnosis of bowel endometriosis. Due to small number of included studies and publication bias, further studies may be needed to validate these results.

Exploratory study of the interest of MR susceptibility-weighted imaging for the pre-operative assessment of pelvic endometriosis extent

OBJECTIVE

To evaluate the performance of magnetic resonance imaging (MRI) with susceptibility-weighted imaging (SWI) in the assessment of endometriosis.

MATERIAL AND METHODS

This prospective study was performed during the diagnostic step or the pre-operative assessment of endometriosis, between June 2017 and April 2018. The MRI was conducted with a 3T MRI device; protocol included T2W, T1W, with and without fat-saturation sequences completed with a SWI sequence: T2-star weighted angiography (SWAN). The diagnostic performance values of MRI and inter-observer agreement were first evaluated with a conventional MR protocol and then with the complementary SWAN sequence by 2 readers. MRI results were correlated with surgical findings in patients who underwent laparoscopy.

RESULTS

74 patients were included in the study, and among them 10 patients were treated by laparoscopy. 81% of the endometriosis lesions had signal losses on the SWAN sequence related to hemorrhagic character whereas only 52% of the lesions had T1-weighted hyperintense implants. Diagnostic performance of the MRI examination was improved by the use of the SWAN sequence compared to the conventional MR protocol (Se = 94% and Spe = 73% in complete protocol and Se = 88% and Spe = 69% in conventional protocol), especially for the involvement of torus uterinus, utero-sacral ligament and retro-cervical site. An excellent interobserver agreement (қ-value = 0,94) was noted between the two readers.

CONCLUSION

SWI can improve the diagnostic accuracy of MRI by allowing the detection of hemorrhagic character of endometriosis lesions.

Systematic radiological approach to utero-ovarian pathologies

Ultrasound is the first-line imaging modality for the evaluation of suspected adnexal masses, endometriosis and uterine tumors, whereas MRI is used as a secondary diagnostic tool to better characterize these lesions. The aim of this review is to summarize the latest advances in the imaging of these utero-ovarian pathologies.

Update on Gadolinium-Based Contrast Agent-Enhanced Imaging in the Genitourinary System

OBJECTIVE. The purpose of this article is to review gadolinium-based contrast agent (GBCA)-enhanced MRI applications in the genitourinary system. CONCLUSION. Nephrogenic systemic fibrosis is rare or nonexistent with standard dosing of group II GBCAs. Gadolinium retention, cost, and examination times are emerging considerations affecting GBCA use. GBCA is unnecessary to diagnose adrenal adenomas, simple cysts, and some Bosniak category II cysts; however, it is required to determine solid or septal renal mass enhancement. Biparametric prostate MRI requires high-quality and reproducible DWI; therefore, dynamic contrast-enhanced MRI remains valuable in selected prostate MRI examinations.

Adenomyosis: A Sonographic Diagnosis

Adenomyosis is a common benign uterine condition and a frequent cause of pelvic pain in premenopausal women. Transvaginal US is now considered the primary imaging modality for the diagnosis of adenomyosis, and thus radiologists should be familiar with its sonographic appearance. US findings can be divided into three categories, which parallel the histology of adenomyosis: (a) ectopic endometrial glands and stroma, (b) muscular hyperplasia/hypertrophy, and (c) increased vascularity. Ectopic endometrial glands manifest as echogenic nodules and striations, radiating from the endometrium into the myometrium. When the glands contain fluid, myometrial cysts and fluid-filled striations may be visible at US. Muscular hyperplasia and hypertrophy cause focal or diffuse myometrial thickening and globular uterine enlargement, often with thin "venetian blind" shadows. The combination of these findings results in a heterogeneous myometrium, with blurring of the endometrial border. Adenomyosis increases uterine vascularity, depicted as a pattern of penetrating vessels at color Doppler US. Other US techniques that are helpful in the diagnosis of adenomyosis include obtaining cine clips and coronal reformatted images, both of which can survey the entire endometrial-myometrial border, and performing saline-infusion sonohysterography, during which ectopic glands frequently fill with either air or fluid. While most cases of adenomyosis develop spontaneously, there are specific inciting causes that include tamoxifen use, postendometrial ablation syndrome, and deep-infiltrating endometriosis. Mimics of adenomyosis include leiomyomas, uterine contractions, neoplasms, and vascular malformations. This article reviews the pathophysiology of adenomyosis and correlates it with the US findings, highlights specific causes of adenomyosis, and describes how to distinguish this common diagnosis from a variety of mimics. Online supplemental material is available for this article. ^©RSNA, 2018.

Imaging techniques in endometriosis

Endometriosis is a common gynecological condition affecting up to 15% of the general female population. Here, we present a systematic review of imaging techniques of endometriosis. The aim of this review is to determine the most accurate site-specific preoperative diagnostic tools in order to map, locate, evaluate the extension, and stage the disease. There are important reasons to stage endometriosis: to create a common language, to enable specificity of diagnosis, standardize comparisons, and to facilitate research applications. The requirements of an ideal endometriosis classification system are that it be empirically and scientifically based, be of general consensus, have unambiguous definition of terms, be comprehensive in all cases, have a simple translation from anatomic features to verbal description, reflect disease, predict fertility, predict pain relief, be useful to guide treatment, indicate risk of recurrence, identify clinical situations in which it does not apply, be simple to calculate, and be easy to communicate to women. An extensive search of papers regarding imaging techniques in endometriosis was performed in Pubmed from January 1992 to February 2018, including original peer-reviewed papers, reviews, and international guidelines.

Deep Infiltrating Endometriosis: Comparison Between 2-Dimensional Ultrasonography (US), 3-Dimensional US, and Magnetic Resonance Imaging

OBJECTIVES

To evaluate the diagnostic accuracy of 2-dimensional (2D) and 3-dimensional (3D) transvaginal ultrasonography (US) in comparison with magnetic resonance imaging (MRI) for identification of deep infiltrating endometriosis.

METHODS

In this prospective observational study, 159 premenopausal women who underwent surgery for a clinical suspicion of deep infiltrating endometriosis were prospectively enrolled. All women underwent 2DUS, 3DUS, and MRI. The following 3 locations of deep endometriosis were considered: (1) intestinal; (2) other posterior lesions (retrocervical septum, rectovaginal septum, uterosacral ligaments, and vaginal fornix); and (3) anterior. The sensitivity, specificity, positive predictive value, and negative predictive value of 2D and 3D transvaginal US in comparison with MRI were determined.

RESULTS

Intestinal deep infiltrating endometriosis was identified by 2DUS in 56 of 66 patients, by 3DUS in 59 of 66, and by MRI in 61 of 66. A receiver operating characteristic curve analysis showed optimal results for 2DUS, 3DUS, and MRI (areas under the curve, 0.86, 0.915, and 0.935, respectively) with a statistically significant difference between 2DUS and MRI (P = .0103), even when the 95% confidence interval showed an overlap. Other posterior deep infiltrating endometriosis was identified by 2DUS in 55 of 75 patients, by 3DUS in 65 of 75, and by MRI in 66 of 75. A receiver operating characteristic curve analysis showed very good results for 2DUS, 3DUS, and MRI (areas under the curve, 0.801, 0.838, and 0.857) with no statistically significant differences. In the 12 women with deep infiltrating endometriosis in the anterior location, the nodules were correctly identified by 2DUS in 3 of 12 patients, by 3DUS in 5 of 12, and by MRI in 6 of 12.

CONCLUSIONS

Our results seem to suggest that there is a statistically significant difference between 2DUS and MRI for the intestinal location of deep infiltrating endometriosis, whereas no differences were found among the techniques for the other locations.

Pitfalls of diffusion-weighted imaging of the female pelvis

Diffusion-weighted imaging (DWI) is widely used in protocols for magnetic resonance imaging (MRI) of the female pelvis. It provides functional and structural information about biological tissues, without the use of ionizing radiation or intravenous administration of contrast medium. High signal intensity on DWI with simultaneous low signal intensity on apparent diffusion coefficient maps is usually associated with malignancy. However, that pattern can also be seen in many benign lesions, a fact that should be recognized by radiologists. Correlating DWI findings with those of conventional (T1- and T2-weighted) MRI sequences and those of contrast-enhanced MRI sequences is mandatory in order to avoid potential pitfalls. The aim of this review article is the description of the most relevant physiological and benign pathological conditions of the female pelvis that can show restricted diffusion on DWI.

Endometriosis: clinical features, MR imaging findings and pathologic correlation

Objective

We illustrate the magnetic resonance imaging (MRI) features of endometriosis.

Background

Endometriosis is a chronic gynaecological condition affecting women of reproductive age and may cause pelvic pain and infertility. It is characterized by the growth of functional ectopic endometrial glands and stroma outside the uterus and includes three different manifestations: ovarian endometriomas, peritoneal implants, deep pelvic endometriosis. The primary locations are in the pelvis; extrapelvic endometriosis may rarely occur. Diagnosis requires a combination of clinical history, invasive and non-invasive techniques. The definitive diagnosis is based on laparoscopy with histological confirmation. Diagnostic imaging is necessary for treatment planning. MRI is as a second-line technique after ultrasound. The MRI appearance of endometriotic lesions is variable and depends on the quantity and age of haemorrhage, the amount of endometrial cells, stroma, smooth muscle proliferation and fibrosis. The purpose of surgery is to achieve complete resection of all endometriotic lesions in the same operation.

Conclusion

Owing to the possibility to perform a complete assessment of all pelvic compartments at one time, MRI represents the best imaging technique for preoperative staging of endometriosis, in order to choose the more appropriate surgical approach and to plan a multidisciplinary team work.

Teaching Points

• Endometriosis includes ovarian endometriomas, peritoneal implants and deep pelvic endometriosis.

• MRI is a second-line imaging technique after US.

• Deep pelvic endometriosis is associated with chronic pelvic pain and infertility.

• Endometriosis is characterized by considerable diagnostic delay.

• MRI is the best imaging technique for preoperative staging of endometriosis.

Anatomy and pathology of the canal of Nuck

The canal of Nuck is the female equivalent of the processus vaginalis in the male but is less well known than its male counterpart. It is a rare entity not commonly encountered by radiologists, particularly in the adult population. Knowledge of the embryology and anatomy of the canal of Nuck is essential for identification of the various pathologic conditions that may occur in this location. Moreover, radiologists should be familiar with this entity to compose an appropriate and thorough differential diagnosis of a labial mass/swelling. In this review, we discuss both the anatomy and the more common pathology that can be encountered within it.

MRI findings in deep infiltrating endometriosis: A pictorial essay

Endometriosis is an important gynaecological disorder which can impact significantly on an individual's quality of life and has major implications on fertility. Deep infiltrating endometriosis is a severe form of endometriosis which can cause obliteration of anatomic compartments. Laparoscopy remains the gold standard for diagnosis of endometriosis, although is an invasive procedure that has the potential to be hindered by obliterative disease. Ultrasound is often employed as the first-line imaging modality when endometriosis is suspected, however, MRI is more accurate in assessment of complex disease. Pre-operative MRI is highly specific in the diagnosis of endometriosis and characterization of disease extent, and plays a key role in guiding surgical management. MRI findings in deep infiltrating endometriosis are described.

Factors that Differentiate between Endometriosis-associated Ovarian Cancer and Benign Ovarian Endometriosis with Mural Nodules

Purpose:

Mural nodules and papillary projections can be seen in benign ovarian endometriosis (OE) and malignant transformation of OE (endometriosis-associated ovarian cancer [EAOC]), which can pose a challenging diagnostic dilemma to clinicians. We identify the preoperative imaging characteristics helpful to the differential diagnosis between benign OE with mural nodules and EAOC.

Materials and Methods:

This was a retrospective study of 82 patients who were diagnosed pathologically to have OE with mural nodules (n = 42) and malignant transformations of these tumors (n = 40) at the Nara Medical University Hospital from January 2008 to January 2015. All patients were assessed with contrast-enhanced MRI before surgery. Patient demographics, and clinical and pathologic features were analyzed to detect the significant differences between the two groups.

Results:

Histological examinations of resected OE tissue specimens revealed that a majority (78.6%) of the mural nodular lesions were retracted blood clots. We found that the patients with malignant mural nodules, when compared to those with benign nodules, were older, had larger cyst diameters and larger mural nodule sizes, and were more likely to exhibit a taller than wider lesion. They were also more likely to present with various signal intensities on T₁-weighted images (T₁WI), high-signal intensity on T₂-weighted images (T₂WI), a lower proportion of shading on T₂WI, and were more likely to show an anterior location of the cyst. In the multivariate logistic regression analysis, “Height” (>1.5 cm) and “Height-Width ratio (HWR)” (>0.9) of mural nodules, maximum diameter of the cyst (>7.9 cm), and age at diagnosis (>43 years) were independent predictors to distinguish EAOC from OE with mural nodules.

Conclusion:

The “Height” and “HWR” of the mural nodules in the cyst may yield a novel potential diagnostic factor for differentiating EAOC from benign OE with mural nodules.

Diagnostic Evaluation of Chronic Pelvic Pain

Chronic pelvic pain can result from various intra- and extra-pelvic etiologies. Although patient history and physical examination may narrow the differential diagnosis, frequently, the different etiologies have overlapping presentations. Imaging examinations such as US and/or MR imaging may help delineate the cause of pain, particularly when related to intra-pelvic organs, pelvic floor dysfunction or prolapse, synthetic material such as pelvic mesh or slings, and in some cases of neuropathic pain. Etiologies of neuropathic pain can also be assessed with non-imaging tests such as nerve conduction studies, electromyography, and testing of sacral reflexes.

Shining light in a dark landscape: MRI evaluation of unusual localization of endometriosis

Endometriosis is a disease distinguished by the presence of endometrial tissue outside the uterine cavity with intralesional recurrent bleeding and resulting fibrosis. The most common locations for endometriosis are the ovaries, pelvic peritoneum, uterosacral ligaments, and torus uterinus. Typical symptoms are secondary dysmenorrhea and cyclic or chronic pelvic pain. Unusual sites of endometriosis may be associated with specific symptoms depending on the localization. Atypical pelvic endometriosis localizations can occur in the cervix, vagina, round ligaments, ureter, and nerves. Moreover, rare extrapelvic endometriosis implants can be localized in the upper abdomen, subphrenic fold, or in the abdominal wall. Magnetic resonance imaging (MRI) represents a problem-solving tool among other imaging modalities. MRI is an advantageous technique, because of its multiplanarity, high contrast resolution, and lack of ionizing radiation. Our purpose is to remind the radiologists the possibility of atypical pelvic and extrapelvic endometriosis localizations and to illustrate the specific MRI findings. Endometriotic tissue with hemorrhagic content can be distinguished from adherences and fibrosis on MRI imaging. Radiologists should keep in mind these atypical localizations in patients with suspected endometriosis, in order to achieve the diagnosis and to help the clinicians in planning a correct and complete treatment strategy.

MR imaging of endometriosis: Spectrum of disease

Endometriosis is a common gynecological disorder defined by the presence of endometrial tissue outside the uterus. It is the most common cause of chronic pelvic pain and typically affects the ovaries, uterine ligaments, peritoneum, tubes, rectovaginal septum and bladder. It may, however, be found at various extrapelvic sites, including the perineum, liver, pancreas, lung or even the central nervous system, and in such cases, diagnosis may be quite challenging. Even though definitive diagnosis requires laparoscopy, preoperative identification of endometriosis is important not only to differentiate it from other diseases with similar clinical presentations but also, for accurate presurgical mapping, since complete removal of all endometriotic foci is critical for the effective treatment of the patient's symptoms. Ultrasound is performed initially, but magnetic resonance imaging (MRI) is increasingly being used, particularly when sonographic findings are unclear, when deep pelvic endometriosis is suspected or when surgery is planned, as it provides better contrast resolution and a larger field of view compared to ultrasound. In this article, we will discuss distinctive MRI appearances of endometriotic foci and we will review common and uncommon locations of endometriosis within the body, in an attempt to familiarize radiologists with its wide spectrum of manifestations.

Magnetic resonance imaging of pelvic endometriosis

Endometriosis is common in women of reproductive age; it can cause pelvic pain and infertility. It is important to diagnose endometriosis and to thoroughly evaluate its extension, especially when surgical treatment is being considered. Magnetic resonance imaging (MRI) with careful examination technique and interpretation enables more accurate and complete diagnosis and staging than ultrasonography, especially in cases of deep pelvic endometriosis. Furthermore, MRI can identify implants in sites that can be difficult to access in endoscopic or laparoscopic explorations. In this article, we describe the appropriate MRI protocol for the study of pelvic endometriosis and the MRI signs of pelvic organ involvement. It is necessary to know the subtle findings and to look for them so we can ensure that they are not overlooked. We describe clinical grading systems for endometriosis and review the diagnostic efficacy of MRI in comparison with other imaging techniques and surgery.

MR Imaging for Incidental Adnexal Mass Characterization

Incidentally detected adnexal masses are common, and the overwhelming majority of them are benign. As many of these adnexal masses are considered indeterminate at CT or US, a large number of benign oophorectomies occur. Of the malignant adnexal masses, high-grade primary ovarian neoplasms with fast doubling times and early dissemination are the most common. Due to their aggressive behavior, diagnosis of malignancy by interval growth on surveillance imaging represents an undesirable option. Immediate MR characterization allows for a decreased rate of benign oophorectomies and expedited triage of patients to definitive treatment when malignancy is suspected.

Magnetic Resonance Imaging (MRI) Depiction of Robert's Uterus: A Rare Müllerian Duct Anomaly Presenting with Cyclical Pain in Young Menstruating Woman

Background

Robert’s uterus is a very rare müllerian duct anomaly which is characterised by septate uterus with obstruction of a one-sided cavity and formation of hematometra. Therefore, patients present with cyclical abdominal pain during menstruation along with normal menstrual flow.

Case Report

We present magnetic resonance imaging (MRI) findings in a case of Robert’s uterus in a young woman.

Conclusions

Robert’s uterus is a very rare anomaly which can be very well characterized by magnetic resonance imaging (MRI). MRI can also show any associated hematometra and endometriomas complicating this condition and aid in the institution of appropriate management in such cases.

Deep pelvic endometriosis: a radiologist's guide to key imaging features with clinical and histopathologic review

While endometriosis typically affects the ovaries, deep infiltrating endometriosis can affect the gastrointestinal tract, urinary tract, and deep pelvis, awareness of which is important for radiologists. Symptoms are nonspecific and can range from chronic abdominal and deep pelvic pain to nausea, vomiting, diarrhea, constipation, hematuria, and rectal bleeding. Ultrasound and computed tomography may show nonspecific soft-tissue density masses causing bowel obstruction and hydronephrosis. This constellation of presenting symptoms and imaging evidence is easily mistaken for other pathologies including infectious gastroenteritis, diverticulitis, appendicitis, and malignancy, which may lead to unnecessary surgery or mismanagement. With this, deep pelvic endometriosis should be considered in the differential diagnosis in a female patient of reproductive age who presents with such atypical symptoms, and further work up with magnetic resonance imaging is imperative for accurate diagnosis, treatment selection, and preoperative planning.

Pelvic Inflammatory Disease: Multimodality Imaging Approach with Clinical-Pathologic Correlation

Pelvic inflammatory disease (PID) is a common medical problem, with almost 1 million cases diagnosed annually. Historically, PID has been a clinical diagnosis supplemented with the findings from ultrasonography (US) or magnetic resonance (MR) imaging. However, the diagnosis of PID can be challenging because the clinical manifestations may mimic those of other pelvic and abdominal processes. Given the nonspecific clinical manifestations, computed tomography (CT) is commonly the first imaging examination performed. General CT findings of early- and late-stage PID include thickening of the uterosacral ligaments, pelvic fat stranding with obscuration of fascial planes, reactive lymphadenopathy, and pelvic free fluid. Recognition of these findings, as well as those seen with cervicitis, endometritis, acute salpingitis, oophoritis, pyosalpinx, hydrosalpinx, tubo-ovarian abscess, and pyometra, is crucial in allowing prompt and accurate diagnosis. Late complications of PID include tubal damage resulting in infertility and ectopic pregnancy, peritonitis caused by uterine and/or tubo-ovarian abscess rupture, development of peritoneal adhesions resulting in bowel obstruction and/or hydroureteronephrosis, right upper abdominal inflammation (Fitz-Hugh-Curtis syndrome), and septic thrombophlebitis. Recognition of these late manifestations at CT can also aid in proper patient management. At CT, careful assessment of common PID mimics, such as endometriosis, adnexal torsion, ruptured hemorrhagic ovarian cyst, adnexal neoplasms, appendicitis, and diverticulitis, is important to avoid misinterpretation, delay in management, and unnecessary surgery. Correlation with the findings from complementary imaging examinations, such as US and MR imaging, is useful for establishing a definitive diagnosis. (©)RSNA, 2016.

Colorectal cancer mimics: a review of the usual suspects with pathology correlation

Colorectal cancer is the third most commonly diagnosed cancer in men and second most commonly diagnosed cancer in women worldwide. Initial diagnosis of colorectal malignancy is generally made on colonoscopy, sigmoidoscopy or digital rectal examination; however, with increased use of CT as primary investigation in patients with lower gastrointestinal symptoms, the diagnosis of colon cancer is often first apparent to a radiologist prior to more invasive tests. CT can demonstrate a discrete soft-tissue mass that narrows the colonic lumen or focal nodular wall thickening/stricture and a variety of pericolonic changes. Pattern of wall thickening has been described as an aid to differential diagnosis; however, significant overlap remains between primary colonic tumor and non-colonic tumors or benign conditions. Imaging is non-specific, and appropriate clinical history, direct inspection, histological analysis, and sometimes discussion at MDT are essential for accurate diagnosis and treatment planning. In this article, we will review the imaging features of some of these benign and malignant mimics of colorectal cancer, with accompanying histology slides where appropriate.