Susceptibility-weighted MRI of extra-ovarian endometriosis: preliminary results

Improved diagnosis of adnexal lesions by integrating intra-tumoral hemorrhage detection with non-contrast MRI scoring (NCMS) using susceptibility-weighted sequences

BackgroundDynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) protocol was included into the Ovarian-Adnexal Reporting & Data System (O-RADS) MRI scoring system. To avoid the administration of contrast medium, the non-contrast MRI scoring (NCMS) system was proposed.PurposeTo evaluate the contribution of detecting intra-tumoral hemorrhage in the solid tissue of adnexal masses to improve tumor characterization and enhance the risk stratification of adnexal lesions using the NCMS system.Material and MethodsMRI findings including susceptibility-weighted sequences (T2*-weighted MR angiography [SWAN]) were retrospectively analyzed in 126 surgically confirmed adnexal tumors with solid tissue components (20 benign, 106 malignant). Solid tissue was classified as malignant based on the NCMS criteria, defined by intermediate intensity on T2-weighted (T2W) imaging, and corresponding diffusion restriction. Hemorrhage was assessed based on high intensity on T1-weighted (T1W) imaging and susceptibility-related signal voids on SWAN.ResultsThe NCMS solid tissue criteria identified malignancy with a sensitivity of 94.3%, specificity of 60%, and accuracy of 88.9%. High intensity on T1W imaging and signal voids on SWAN were observed in 23.6% and 72.6% of malignant lesions, compared to 0% and 5% in benign lesions, respectively. Hemorrhage was frequently observed in high-grade malignant tumors, or hemorrhagic subtypes. The combination of NCMS criteria and/or presence of intra-tumoral hemorrhage was associated with malignancy, yielding a sensitivity of 98.1%, specificity of 60%, and accuracy of 92.1%.ConclusionThe inclusion of intra-tumoral hemorrhage enhances the diagnostic accuracy of the NCMS for characterizing adnexal lesions. SWAN may also aid in estimating tumor grade and identifying hemorrhagic subtypes.

CAR/CSAR Practice Statement on Pelvic MRI for Endometriosis

The Canadian Association of Radiologists (CAR) Endometriosis Working Group was tasked with providing guidance and benchmarks to ensure the quality of technique and interpretation for advanced imaging modalities associated with diagnosing endometriosis. Advanced pelvic ultrasound is essential in diagnosing and mapping pelvic endometriosis, but pelvic MRI serves as an excellent imaging tool in instances where access to advanced ultrasound is limited, or an alternative imaging modality is required. Despite the known utility of MRI for endometriosis, there is no consensus on imaging protocol and patient preparation in Canada. To improve patient care and support excellence in imaging, the Working Group has developed recommendations for the use of pelvic MRI to assess for endometriosis with an aim to standardize MRI technique for use in both community and academic practices across Canada. The guidelines provide recommendations regarding imaging technique and patient preparation for pelvic MRI, along with suggestions for structured reporting of pelvic MRI for endometriosis.

Magnetic Resonance Imaging of Endometriosis: The Role of Advanced Techniques

Endometriosis is a chronic inflammatory disease that affects about 10% of women, and it is characterized by the presence of endometrial tissue outside the uterine cavity. Associated symptoms are dyspareunia, chronic pelvic pain, and infertility. The diagnosis of endometriosis can be challenging due to various clinical and imaging presentations. Laparoscopy is the gold standard for the diagnosis, but it is an invasive procedure. The literature has increasingly promoted a switch to less invasive imaging techniques, such as ultrasound and magnetic resonance imaging (MRI). The latter, also in relation to the latest technological advances, allows a comprehensive and accurate assessment of the pelvis and it can also identify sites of endometriosis that escape laparoscopic evaluation. Furthermore, MRI has been found to be more accurate than other imaging techniques in relation to its improved sensitivity and specificity in identifying disease sites, also due to the role of new emerging sequences. This article aims to review the current role of advanced MRI applications in the assessment of endometriosis.

Endometriosis, a common but enigmatic disease with many faces: current concept of pathophysiology, and diagnostic strategy

Endometriosis is a benign, common, but controversial disease due to its enigmatic etiopathogenesis and biological behavior. Recent studies suggest multiple genetic, and environmental factors may affect its onset and development. Genomic analysis revealed the presence of cancer-associated gene mutations, which may reflect the neoplastic aspect of endometriosis. The management has changed dramatically with the development of fertility-preserving, minimally invasive therapies. Diagnostic strategies based on these recent basic and clinical findings are reviewed. With a focus on the presentation of clinical cases, we discuss the imaging manifestations of endometriomas, deep endometriosis, less common site and rare site endometriosis, various complications, endometriosis-associated tumor-like lesions, and malignant transformation, with pathophysiologic conditions.

[Classification of Uterine Adenomyosis: A Pictorial Essay]

MRI is a crucial tool for diagnosing adenomyosis and identifying its related pathologies. To accurately diagnose adenomyosis, it is necessary to recognize both the typical MRI findings and atypical features of the condition. Recently, a standardized classification system has been developed to facilitate precise presurgical diagnosis of adenomyosis and to determine the appropriate treatment method. Differentiating between various subtypes based on MRI-based classification and identifying different MRI phenotypes can aid in categorizing patients with adenomyosis into specific treatment groups and monitoring their response to therapy.

Diagnosis of pelvic endometriosis: a preliminary study on the added value of R2*MFGRE sequence in magnetic resonance imaging

BACKGROUND

Identifying and locating endometriotic lesions is crucial for preoperative planning, so new magnetic resonance imaging (MRI) techniques are urgently needed to improve the diagnostic sensitivity for pelvic endometriosis.

PURPOSE

To evaluate the feasibility of R2* multiple fast gradient recalled echo (MFGRE) imaging in the diagnosis of pelvic endometriosis.

MATERIAL AND METHODS

A total of 46 patients with suspected endometriosis underwent routine pelvic MRI and R2*MFGRE imaging. Clinical diagnosis was pathologically confirmed one month after MRI examination. Three radiologists who were blinded to the pathological results evaluated the number of ovarian endometriomas (OMAs) and deep infiltrating endometriosis (DIE) lesions using routine MRI and its combination with R2*MFGRE. The diagnostic sensitivity for OMA or DIE using the two examination methods was determined. Two-correlation sample rank-sum tests were used to compare both methods. Additionally, for all lesions, the R2* values were measured and statistically analyzed.

RESULTS

Among 46 patients, 47 OMAs and 30 DIE lesions were found surgically and pathologically confirmed. The diagnostic sensitivity of the routine MRI was 87.2% for OMA and 46.7% for DIE. The diagnostic sensitivity of the routine imaging combined with R2*MFGRE was 100% for OMA and 90% for DIE. The two-correlation sample rank-sum test showed a significant difference between both methods (P<0.01, z = -4.26). The median R2* value was 25.20 (IQR=14) for the OMA group, and 45.21 (IQR=40) for the DIE group. The difference between both groups was statistically significant (P<0.01, z = -4.89).

CONCLUSION

R2*MFGRE imaging, as a supplement to the routine MRI, could improve the diagnostic sensitivity for pelvic endometriosis, especially for DIE.

T2*-Weighted Imaging Performance in the Detection of Deep Endometriosis among Readers with Different Experience: Comparison with Conventional MRI Sequences

Magnetic resonance imaging (MRI) is an effective technique for the diagnosis and preoperative staging of deep infiltrative endometriosis (DIE). The usefulness of MRI sequences susceptible to chronic blood degradation products, such as T2*-weighted imaging, remains uncertain. The present study aims to evaluate the diagnostic performance of these sequences in addition to the conventional protocol for DIE assessment. Forty-four MRI examinations performed for clinical and/or ultrasound DIE suspicion were evaluated by three readers with variable experience in female imaging. The inter-observer agreement between the reader who analysed only the conventional protocol and the one who also considered T2*-weighted sequences was excellent. The less experienced reader diagnosed a significantly higher number of endometriosis foci on the T2*-weighted sequences compared with the most experienced observer. T2*-weighted sequences do not seem to provide significant added value in the evaluation of DIE, especially in less experienced readers. Furthermore, artifacts caused by undesirable sources of magnetic inhomogeneity may lead to overdiagnosis.

Accuracy of transvaginal ultrasound and magnetic resonance imaging for diagnosis of deep endometriosis in bladder and ureter: a meta-analysis

This meta-analysis aimed to determine the accuracy of transvaginal ultrasound (TVS) and pelvic magnetic resonance imaging (MRI) in diagnosing urinary tract endometriosis (UTE). A comprehensive search of the Pubmed and Embase was conducted between January 1989 and June 2020. Studies that described the accuracy of MRI or TVS for the diagnosis of UTE using surgical data as the reference standard were included. Of the 913 citations identified, 23 studies were analysed. For detection of endometriosis in bladder endometriosis (BE), the overall pooled sensitivities of TVS and MRI were 72% and 68% respectively, and their specificities were 99% and 100% respectively. For detection of endometriosis in the ureteral endometriosis (UE), the overall pooled sensitivities of TVS and MRI were 97% and 87% respectively, and their specificities were both 100%. In conclusion, both TVS and MRI provide good accuracy with specific strong points in diagnosing UTE and seem useful first-line methods from a clinical perspective. Besides, pelvic MRI and TVS are more accurate for predicting UTE localised in the ureter than bladder, especially in terms of sensitivity.IMPACT STATEMENTWhat is already known on this subject? Previous studies have confirmed high diagnostic value of transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI) on bladder endometriosis (BE) respectively. However, high heterogeneity was found for both sensitivity and specificity and no meta-analysis has yet been performed to test the diagnostic value of TVS and MRI for ureteral endometriosis (UE).What the results of this study add? In this meta-analysis, we firstly confirmed high diagnostic value of TVS and MRI on UE respectively. For detection of UE, the overall pooled sensitivities of TVS and MRI were 97% and 87% respectively, and their specificities were both 100%.What the implications are of these findings for clinical practice and/or further research? Early preoperative diagnosis and accurate understanding of the widespread distribution of endometriosis are prerequisites for radical surgical in UTE. In the present study, we updated the previous results on the accuracy of TVS and MRI for the diagnosis of BE and firstly confirmed high diagnostic value of TVS and MRI on UE. Both TVS and MRI provide good accuracy with specific strong points in diagnosing UTE and seem useful first-line methods from a clinical perspective.

MRI for the diagnosis and staging of deeply infiltrating endometriosis: a national survey of BSGE accredited endometriosis centres and review of the literature

OBJECTIVES

Our objective was to establish the primary mode of imaging and MR protocols utilised in the preoperative staging of deeply infiltrating endometriosis in centres accredited by the British Society of Gynaecological Endoscopy (BSGE).

METHODS

The lead consultant radiologist in each centre was invited to complete an online survey detailing their protocols.

RESULTS

Out of 49 centres, 32 (65%) responded to the survey. Two centres performed transvaginal ultrasound as the primary method for preoperative staging of deeply infiltrating endometriosis and the remainder performed MRI. 21/25 centres did not recommend a period of fasting prior to MRI and 22/25 administered hyoscine butylbromide. None of the centres routinely offered bowel preparation or recommended a specific pre-procedure diet. 21/25 centres did not time imaging according to the woman's menstrual cycle, and instructions regarding bladder filling were varied. Rectal and vaginal opacification methods were infrequently utilised. All centres preferentially performed MRI in the supine position - six used an abdominal strap and four could facilitate prone imaging. Just under half of centres used pelvic-phased array coils and three centres used gadolinium contrast agents routinely. All centres performed T1W with fat-suppression and T2W without fat-suppression sequences. There was significant variation relating to other MR sequences depending on the unit.

CONCLUSIONS

There was significant inconsistency between centres in terms of MR protocols, patient preparation and the sequences performed. Many practices were out of line with current published evidence.

ADVANCES IN KNOWLEDGE

Our survey demonstrates a need for evidence-based standardisation of imaging in BSGE accredited endometriosis centres.

Multimodality imaging review for suspected ovarian torsion cases in children

OBJECTIVES

Ovarian torsion (OT), although rare, can be described as a complete or partial twist of the ovary with impairment of blood flow. Although occurring at any age, it is more common in children and during pregnancy. Presenting symptoms are non-specific but include either persistent or intermittent acute abdominal pain, making early diagnosis difficult. Delayed diagnosis is associated with an increased need for oophorectomy. The aim of this literature review is to establish the safest and most efficacious imaging strategy for OT by comparing and contrasting evidence for current imaging modalities found in the literature.

KEY FINDINGS

Characteristically, OT can be identified through a combination of findings some of which includes an enlarged ovary, multiple follicles at the periphery and a "whirlpool" sign. Currently, ultrasound is the preferred primary imaging modality; although computed tomography (CT) and magnetic resonance imaging (MRI) may also be used when findings are equivocal; with MRI being the safer option.

CONCLUSION

Ultimately, while it is true that ovarian torsion is not a common cause of acute abdominal pain in children, it should always be considered in the differential diagnosis. Prior to selecting an imaging modality; the clinical presentation, age group, possible radiation dose and availability of the modality needs to be considered to ensure the appropriate imaging strategy.

IMPLICATIONS FOR PRACTICE

With new tools such as scoring systems, B-flow imaging (BFI), diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI) currently being explored for possible use in the future, early diagnosis of OT may be attainable. Thus, reducing the likelihood of adverse complications and consequently the need for oophorectomy.

Advances in MR Imaging of the Female Pelvis

This article focuses on advanced MR imaging techniques of the female pelvis and clinical applications for benign and malignant disease. General and abbreviated protocols for female pelvic MR imaging are reviewed. Diffusion-weighted imaging, dynamic contrast-enhanced MR imaging, and susceptibility-weighted imaging are discussed in the context of adnexal mass characterization using the ADNEx-MR scoring system, evaluation of endometriosis, local staging of cervical and endometrial cancers, assessment of nodal and peritoneal metastasis, and potential detection of leiomyosarcoma. MR defecography is also discussed regarding evaluation of multicompartmental pelvic floor disorders.

Pelvic MRI in the diagnosis and staging of pelvic endometriosis: added value of structured reporting and expertise

PURPOSE

To compare the diagnostic characteristics of routine-read (RR), structured-reported read (SR), and structured expert-read pelvic (SER) MRI for staging of pelvic endometriosis in a tertiary care academic center.

METHODS

Of 530 patients with endometriosis (2013-2018), 59/530 (11.1%) were staged surgically and underwent pelvic MRI. Radiology reports were considered RR; MRI studies were independently reassessed by SR and SER. Involvement was recorded by compartment [anterior (AC), middle (MC), posterior (PC), adnexal (AX), and other (OC)]. Diagnostic discrepancy between review methods was assessed with McNemar's test. Interobserver agreement was assessed using Cohen's unweighted kappa.

RESULTS

Of 295 compartments in 59 women (mean age = 38.8 years; range 20-69), 147/295 (49.8%) had confirmed endometriosis. Overall sensitivity: RR = 42.9%; SR = 86.4%; SER = 74.2%. SR's increased sensitivity was significant for PC (p < 0.001), MC (p < 0.001), AC (p = 0.001), AX (p = 0.038). Higher sensitivity by SER was significant for PC (p < 0.001), MC (p = 0.004) and AC (p < 0.001), but not AX (p > 0.05). Overall specificity: RR = 95.3%; SR = 45.9%; SER = 81.8%. SER specificity was no different than RR for PC or AX (p > 0.5). RR sensitivity relied heavily on detection of AX involvement, whereas SR and SER showed additional sites of disease while maintaining comparable specificity for SER. Overall agreement between SR and SER was fair [k = 0.342 (95% CI 0.25, 0.44)].

CONCLUSIONS

Even at a tertiary care academic center, SER outperforms both SR and RR in the assessment of pelvic endometriosis. Although lack of expertise may negatively impact specificity, use of structured reporting is significantly more sensitive than RR. Therefore, its use can be of assistance in surgical planning and patient counseling.

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.

European society of urogenital radiology (ESUR) guidelines: MR imaging of pelvic endometriosis

Endometriosis is a common gynaecological condition of unknown aetiology that primarily affects women of reproductive age. The accepted first-line imaging modality is pelvic ultrasound. However, magnetic resonance imaging (MRI) is increasingly performed as an additional investigation in complex cases and for surgical planning. There is currently no international consensus regarding patient preparation, MRI protocols or reporting criteria. Our aim was to develop clinical guidelines for MRI evaluation of pelvic endometriosis based on literature evidence and consensus expert opinion. This work was performed by a group of radiologists from the European Society of Urogenital Radiology (ESUR), experts in gynaecological imaging and a gynaecologist expert in methodology. The group discussed indications for MRI, technical requirements, patient preparation, MRI protocols and criteria for the diagnosis of pelvic endometriosis on MRI. The expert panel proposed a final recommendation for each criterion using Oxford Centre for Evidence Based Medicine (OCEBM) 2011 levels of evidence.

KEY POINTS

• This report provides guidelines for MRI in endometriosis. • Minimal and optimal MRI acquisition protocols are provided. • Recommendations are proposed for patient preparation, best MRI sequences and reporting criteria.

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.

Magnetic resonance imaging of acquired disorders of the pediatric female pelvis other than neoplasm

Transabdominal US remains the primary screening imaging modality of the pediatric female pelvis. However, MRI has become an invaluable adjunct to US in recent years. MRI offers superb soft-tissue contrast resolution that allows for detailed evaluation, particularly of the ovaries and their associated pathology. MRI can yield diagnostic information that is similar to or even better than that of US, especially in nonsexually active girls in whom transvaginal US would be contraindicated. MRI is generally a second-line examination and is preferred over CT because it does not involve the use of ionizing radiation. MRI might be underutilized in this population, particularly in differentiating surgical from nonsurgical conditions. This article reviews the relevant anatomy and discusses imaging of acquired conditions that involve the pediatric female genital tract, illustrating associated pathology with case examples.