The utility of ultrasound elastography in differentiation of endometriomas and hemorrhagic ovarian cysts

Ultrasound Elastography in Benign Gynecology: A Scoping Review

OBJECTIVE

To perform a scoping review of the literature in which ultrasound elastography (UE) has been used in benign gynecology and identify avenues for its use in future research and clinical implementations.

METHODS

A structured search of EMBASE, Medline and Cochrane databases was conducted (last search date April 15th, 2022). Eligible studies included adult participants with female pelvic anatomy. English language papers focusing on the utility of ultrasound elastography applied to benign gynecology were included. Narrative reviews, conference abstracts, and letters to the editor were excluded. Two independent reviewers screened titles and abstracts for inclusion, a third reviewer was consulted in cases of disagreement. Study quality was assessed by a checklist for study implementation and elastography technique. Extracted data included elastography technology, gynecologic application, opportunities for clinical implementation, and strengths and limitations.

RESULTS

The search returned 2026 studies. A total of 40 studies, published between 2013 and 2022, were retained for data extraction. Studies most frequently used shear wave elastography as the method of UE (n = 23), followed by strain elastography (n = 13) and acoustic radiation force impulse (n = 4). Most common clinical applications for UE were the diagnosis of adenomyosis and uterine fibroids (27.5%), assessment of pelvic floor muscle function (22.5%), and describing the elastic properties of polycystic ovaries (17.5%) and the uterine cervix (15.0%). Limitations of the technology were identified as the lack of published reference values for gynecologic organs and difficulties in assessing tissues deep to the transducer.

CONCLUSION

Future research is needed to validate the use of ultrasound elastography in gynecology under both normal and pathologic conditions.

Shear wave elastography to assess stiffness of the human ovary and other reproductive tissues across the reproductive lifespan in health and disease†

The ovary is one of the first organs to show overt signs of aging in the human body, and ovarian aging is associated with a loss of gamete quality and quantity. The age-dependent decline in ovarian function contributes to infertility and an altered endocrine milieu, which has ramifications for overall health. The aging ovarian microenvironment becomes fibro-inflammatory and stiff with age, and this has implications for ovarian physiology and pathology, including follicle growth, gamete quality, ovulation dynamics, and ovarian cancer. Thus, developing a non-invasive tool to measure and monitor the stiffness of the human ovary would represent a major advance for female reproductive health and longevity. Shear wave elastography is a quantitative ultrasound imaging method for evaluation of soft tissue stiffness. Shear wave elastography has been used clinically in assessment of liver fibrosis and characterization of tendinopathies and various neoplasms in thyroid, breast, prostate, and lymph nodes as a non-invasive diagnostic and prognostic tool. In this study, we review the underlying principles of shear wave elastography and its current clinical uses outside the reproductive tract as well as its successful application of shear wave elastography to reproductive tissues, including the uterus and cervix. We also describe an emerging use of this technology in evaluation of human ovarian stiffness via transvaginal ultrasound. Establishing ovarian stiffness as a clinical biomarker of ovarian aging may have implications for predicting the ovarian reserve and outcomes of Assisted Reproductive Technologies as well as for the assessment of the efficacy of emerging therapeutics to extend reproductive longevity. This parameter may also have broad relevance in other conditions where ovarian stiffness and fibrosis may be implicated, such as polycystic ovarian syndrome, late off target effects of chemotherapy and radiation, premature ovarian insufficiency, conditions of differences of sexual development, and ovarian cancer. Summary sentence:  Shear Wave Elastography is a non-invasive technique to study human tissue stiffness, and here we review its clinical applications and implications for reproductive health and disease.

Radiological Evidence of Testicular Damage in Severe Acute Respiratory Syndrome Coronavirus 2 Infection: A Sonoelastography's Potential Role

ABSTRACT

This preliminary study aimed to evaluate the possible damage to the male reproductive system that the severe acute respiratory syndrome coronavirus 2 virus causes by quantitatively measuring and comparing the tissue stiffness of the testis and epididymis with acoustic radiation force impulse sonoelastography in patients who have COVID-19 with a healthy control group. This prospective study was conducted between February and July 2021 with 65 cases. We used sonoelastography to evaluate male patients 18 years or older, who had applied to the urology clinic with nontesticular complaints, and were found to not have any underlying testicular pathology after a clinical-laboratory evaluation. The clinical-laboratory imaging findings and reverse transcription-polymerase chain reaction test results of all patients diagnosed with COVID-19 were reviewed from the hospital database. We measured the shear wave velocity values of the epididymis and the testes of 31 proven severe acute respiratory syndrome coronavirus 2 patients and 34 healthy subjects and compared them with an independent t test. For the patient and control group subjects, the mean age was 37.55 ± 13.08 (23-71) and 40.5 ± 16.25 (18-81) years, respectively. The mean shear wave velocity values of the left-right and bilateral testes and epididymis of the patient group were statistically substantially higher ( P ˂ 0.05) than in the control group. In the receiver operating characteristic analysis, when the cutoff values for the bilateral testes and epididymis were determined as 1.39 and 1.64 m/s, respectively, the AUC was 77% to 73.4%, the sensitivity was 87% to 74%, and the specificity was 65% to 62%. Our findings show that testicular and epididymal tissue stiffness increased in patients with COVID-19. We recommend adding sonoelastography to urogenital examinations of male reproductive system in patients who are recovering from COVID-19.

Ultrasound Elastography for the Diagnosis of Endometriosis and Adenomyosis: A Systematic Review with Meta-analysis

Elastography is capable of measuring tissue mechanical properties and elasticity. It is used to help diagnose various diseases, although its use in pelvic endometriosis remains to be established. A systematic review and meta-analysis were conducted to assess transvaginal ultrasound elastography for the diagnosis of different manifestations of endometriosis and adenomyosis. PRISMA guidelines were used for a Medline, PubMed, Embase, BVS/Bireme, Scopus, Cochrane Library and Escudos database search. Studies indexed until March 2021 that evaluated elastography compared with histopathological results (gold standard), ultrasound or magnetic resonance imaging for diagnosis of pelvic endometriosis and adenomyosis were eligible. The Rayyan platform was used to select studies. Sensitivity (S), specificity (Ps), positive and negative predictive values and receiver operating characteristic curves were calculated for elastographic diagnosis of endometriosis. A meta-analysis using Review Manager 5 and Open Meta Analyst was performed. Bias risk in the studies was analyzed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool. This systematic review was prospectively registered in the PROSPERO database: CRD42021244555. Among the 163 identified citations, 10 studies were eligible for review (5 for diagnosis of adenomyosis, 2 for endometrioma, 3 for deep intestinal endometriosis and rectovaginal septum [deep pelvic endometriosis], N = 744 women). In deep pelvic endometriosis, lesions diagnosed by elastography were found to correlate with histopathology results. Increased "stiffness" (elastography) was associated with a higher fibrotic component, with S = 78%-100% and Ps = 100%, according to the authors. On elastography, endometriomas were stiffer than hemorrhagic cysts (S = 82%, Ps = 79%) and malignant tumors (S = 86%, Ps = 100%). For these lesions, a meta-analysis could not be performed because the small number of studies and insufficient data. In adenomyosis, meta-analysis and receiver operating characteristic curve analysis revealed that elastography had good sensitivity and specificity. Studies indicated a low bias risk by QUADAS-2. Elastography had high sensitivity and specificity for deep pelvic endometriosis diagnosis, and its findings correlated with histopathology results. For adenomyosis, the meta-analysis confirmed the sensitivity and specificity results of the studies. Given these results, elastography may be a promising imaging test, contributing to non-invasive diagnosis of endometriosis and adenomyosis.

Ultrasonography in the Differentiation of Endometriomas from Hemorrhagic Ovarian Cysts: The Role of Texture Analysis

The ultrasonographic (US) features of endometriomas and hemorrhagic ovarian cysts (HOCs) are often overlapping. With the emergence of new computer-aided diagnosis techniques, this is the first study to investigate whether texture analysis (TA) could improve the discrimination between the two lesions in comparison with classic US evaluation. Fifty-six ovarian cysts (endometriomas, 30; HOCs, 26) were retrospectively included. Four classic US features of endometriomas (low-level internal echoes, perceptible walls, no solid components, and less than five locules) and 275 texture parameters were assessed for every lesion, and the ability to identify endometriomas was evaluated through univariate, multivariate, and receiver operating characteristics analyses. The sensitivity (Se) and specificity (Sp) were calculated with 95% confidence intervals (CIs). The texture model, consisting of seven independent predictors (five variations of difference of variance, image contrast, and the 10th percentile; 100% Se and 100% Sp), was able to outperform the ultrasound model composed of three independent features (low-level internal echoes, perceptible walls, and less than five locules; 74.19% Se and 84.62% Sp) in the diagnosis of endometriomas. The TA showed statistically significant differences between the groups and high diagnostic value, but it remains unclear if the textures reflect the intrinsic histological characteristics of the two lesions.

Ultrasound Shear Wave Velocity Varies Across Anatomical Region in Ex Vivo Bovine Ovaries

The physical properties of the ovarian extracellular matrix (ECM) regulate the function of ovarian cells, specifically the ability of the ovary to maintain a quiescent primordial follicle pool while allowing a subset of follicles to grow and mature in the estrous cycle. Design of a long-term, cycling artificial ovary has been hindered by the limited information regarding the mechanical properties of the ovary. In particular, differences in the mechanical properties of the two ovarian compartments, the cortex and medulla, have never been quantified. Shear wave (SW) ultrasound elastography is an imaging modality that enables assessment of material properties, such as the mechanical properties, based on the velocity of SWs, and visualization of internal anatomy, when coupled with B-mode ultrasound. We used SW ultrasound elastography to assess whole, ex vivo bovine ovaries. We demonstrated, for the first time, a difference in mechanical properties, as inferred from SW velocity, between the cortex and medulla, as measured along the length (cortex: 2.57 ± 0.53 m/s, medulla: 2.87 ± 0.77 m/s, p < 0.0001) and width (cortex: 2.99 ± 0.81 m/s, medulla: 3.24 ± 0.97 m/s, p < 0.05) and that the spatial distribution and magnitude of SW velocity vary between these two anatomical planes. This work contributes to a larger body of literature assessing the mechanical properties of the ovary and related cells and specialized ECMs and will enable the rational design of biomimetic tissue engineered models and durable bioprostheses. Impact Statement Shear wave (SW) ultrasound elastography can be used to simultaneously assess the material properties and tissue structures when accompanied with B-mode ultrasound. We report a quantitative difference in mechanical properties, as inferred from SW velocity, between the cortex and medulla, with SW velocity being 11.4% and 8.4% higher in the medulla than the cortex when measured along the length and width, respectively. This investigation into the spatial and temporal variation in SW velocity in bovine ovaries will encourage and improve design of more biomimetic scaffolds for ovarian tissue engineering.

Diagnosing Deep Endometriosis Using Transvaginal Elastosonography

Transvaginal ultrasound (TVUS) and MRI are currently two mainstream imaging techniques used to diagnose deep endometriosis (DE) with comparable accuracy, but there is still ample room for improvement. As endometriotic lesions progress to fibrosis concomitant with the increase in tissue stiffness, transvaginal elastosonography (TVESG) is well-suited for diagnosing DE. To test the hypothesis that lesional stiffness as measured by TVESG correlates with the extent of lesional fibrosis, the markers of progression, hormonal receptor expression, and vascularity, we recruited 30 patients suspected to have DE who went through pelvic examination, TVUS and/or MRI, and TVESG and were ultimately diagnosed by histology. Their lesional tissue samples were subjected to immunohistochemistry analysis of markers for epithelial-mesenchymal transition (EMT), fibroblast-to-myofibroblast transdifferentiation (FMT), estrogen and progesterone receptors (ERβ and PR), microvessel density (MVD), and vascularity, as well as quantification of lesional fibrosis. We found that pelvic examination, TVUS, and MRI detected 83.3%, 66.7%, and 83.3% of all DE cases, respectively, while TVESG detected them all. The lesions missed by pelvic exam, TVUS and MRI were significantly smaller than those detected but nonetheless had higher lesional stiffness. Lesional stiffness correlated closely and positively with the extent of lesional fibrosis, negatively with the markers of EMT, MVD, vascularity, and PR expression, but positively with the marker for FMT and ERβ. Thus, through the additional use of information on differential stiffness between DE lesions and their surrounding tissues, TVESG improves diagnostic accuracy, provides a ballpark estimate on the developmental stage of the lesions, and may help clinicians choose the best treatment modality.

Focused ultrasound for the diagnosis of non-palpable endometriotic lesions of the abdominal wall: a not-uncommon surgical complication

Endometriosis is a benign disease characterized by endometrial glands and stroma outside the endometrial cavity. We reported two cases of endometriosis of the abdominal wall, with subcutaneous and intramuscular localization, that became symptomatic a few years after a cesarean intervention. These cases have a clinical pattern quite similar to cutaneous endometriosis, but they are more difficult to diagnose through physical examination because they are barely palpable. In this sense, coupled with suggestive symptoms, ultrasound examination can confirm the clinical suspicion of endometriosis without the use of computed tomography and/or magnetic resonance imaging.

Ultrasonic Elastography Evaluation in Optic Neuritis

PURPOSE

In the present study, we attempted to determine whether ultrasonic elastography (USE) evaluation can be used in a diagnosis of optic neuritis (ON).

MATERIALS AND METHODS

Thirteen patients who each had one normal eye and one eye with a diagnosis of ON were included in the study. Ultrasonography (US) and USE examinations were performed on the affected and non-affected eyes of all participants. Optic nerve and adjacent fat tissue regions at the same depth were selected, and USE measurements were obtained. The optic nerve diameter was measured in both normal and affected eyes.

RESULTS

The mean USE values for the optic nerve were 2.58 ± 0.50 m/s in ON eyes and 1.91 ± 0.39 m/s in normal eyes (p = 0.001). The mean USE values for the optic-nerve adjacent tissue were 2.26 ± 0.45 m/s in ON eyes and 1.77 ± 0.22 m/s in normal eyes (p = 0.001). The mean optic-nerve diameter was 3.80 ± 1.09 mm in ON eyes and 3.28 ± 0.98 mm in normal eyes (p = 0.005).

CONCLUSIONS

USE may be considered an accessible, safe technique for the detection of significant optic-nerve tissue stiffness in ON and may be used an adjunctive tool for confirming this diagnosis.