Diagnostic accuracy of diffusion-weighted imaging with conventional MR imaging for differentiating complex solid and cystic ovarian tumors at 1.5T

Diagnostic Value of MRI Compared to Histopathological Results in Differentiating Benign from Malignant Ovarian Masses

Introduction and aim: Ovarian cancer is a prevalent neoplastic condition among females. Early diagnosis is essential in improving patient outcomes. This study aimed to determine the diagnostic value of magnetic resonance imaging (MRI) compared to histopathological diagnosis to distinguish between benign and malignant ovarian masses. Methods:The present cross-sectional study, which was conducted between 2021 and 2022, included a cohort of women with ovarian mass. Gyneco-oncologists referred all patients to the MRI center. The imaging protocol encompassed T1 and T2 weighted images, T1 fat-suppressed sequence, post-contrast and diffusion-weighted images (DWI). After surgery, the histopathological results were compared to the MRI diagnosis. Statistical analysis was done by using SPSS v.25 software. Results:A total of 67 women aged 15-82 years old were included in this study. Compared to histopathological diagnosis, MRI had a sensitivity of 96%, a specificity of 69%, a positive predictive value of 64.9% and a negative predictive value of 96.7%. Among patients under 40 years old, MRI showed a sensitivity of 100%, a specificity of 76.2%, a positive predictive value of 72.2% and a negative predictive value of 100%. Solid component and contrast enhancement within the solid component was significantly more frequent in patients with malignant diagnoses than those with benign masses (p<0.05). Conclusion:According to the results of the study, MRI is valuable for discriminating between benign and malignant ovarian masses, especially in patients under 40.

Discriminating Between Benign and Malignant Solid Ovarian Tumors Based on Clinical and Radiomic Features of MRI

RATIONALE AND OBJECTIVES

To develop and validate a combined model integrating clinical and radiomic features to non-invasive discriminate between the benign and malignant solid ovarian tumors.

MATERIALS AND METHODS

A total of 148 patients with 156 solid ovarian tumors (86 benign and 70 malignant tumors) were included in this study. The dataset was split into the training and the test set with a ratio of 8:2 using stratified random sampling. 12 clinical features and 1612 radiomic features were extracted from each tumor. These features were selected by least absolute shrinkage and selection operator (Lasso). Three classification models were built using extreme gradient boosting (XGB) algorithm: clinical model, radiomic model, combined model. The area under the receiver operating characteristic curve (AUC), accuracy, precision and sensitivity were analyzed to evaluate the performance of these models.

RESULTS

All of the three models obtained good performances in differentiating benign with malignant solid ovarian tumors in both training and test sets. The AUC, accuracy, precision, sensitivity of clinical model and radiomic model in test set were 0.847 (95% confidence interval (CI), 0.707-0.986, p <0.01), 0.774, 0.769, 0.714, and 0.807 (95%CI, 0.652-0.961, p <0.05), 0.677, 0.643, 0.643, respectively. Combined model had the best prediction results, the AUC, accuracy, precision and sensitivity were 0.954 (95%CI, 0.862-1.0, p <0.01), 0.839, 0.909 and 0.714 in test set.

CONCLUSION

Radiomics based on machine learning can be helpful for radiologists in differentiating the benign and malignant solid ovarian tumors.

Intravoxel Incoherent Motion (IVIM) MR Quantification in Locally Advanced Cervical Cancer (LACC): Preliminary Study on Assessment of Tumor Aggressiveness and Response to Neoadjuvant Chemotherapy

The aim of this study was to determine whether quantitative parameters obtained from intravoxel incoherent motion (IVIM) model at baseline magnetic resonance imaging (MRI) correlate with histological parameters and response to neoadjuvant chemotherapy in patients with locally advanced cervical cancer (LACC). Methods: Twenty patients with biopsy-proven cervical cancer, staged as LACC on baseline MRI and addressed for neoadjuvant chemotherapy were enrolled. At treatment completion, tumor response was assessed with a follow-up MRI evaluated using the revised response evaluation criteria in solid tumors (RECIST; version 1.1), and patients were considered good responders (GR) if they had complete response or partial remission, and poor responders/non-responders (PR/NR) if they had stable or progressive disease. MRI protocol included conventional diffusion-weighted imaging (DWI; b = 0 and 1000 s/mm²) and IVIM acquisition using eight b-values (range: 0–1500 s/mm²). MR-images were analyzed using a dedicated software to obtain quantitative parameters: diffusion (D), pseudo-diffusion (D*), and perfusion fraction (fp) from the IVIM model; apparent diffusion coefficient (ADC) from conventional DWI. Histologic subtype, grading, and tumor-infiltrating lymphocytes (TILs) were assessed in each LACC. Results: D showed significantly higher values in GR patients (p = 0.001) and in moderate/high TILs (p = 0.018). Fp showed significantly higher values in squamous cell tumors (p = 0.006). Conclusions: D extracted from the IVIM model could represent a promising tool to identify tumor aggressiveness and predict response to therapy.

The Diagnostic Performance of Maximum Uptake Value and Apparent Diffusion Coefficient in Differentiating Benign and Malignant Ovarian or Adnexal Masses: A Meta-Analysis

Objective

The purpose of this meta-analysis was to provide evidence for using maximum uptake value (SUVmax) and apparent diffusion coefficient (ADC) to quantitatively differentiate benign and malignant ovarian or adnexal masses, and to indirectly compare their diagnostic performance.

Material and Methods

The association between SUVmax, ADC and ovarian or adnexal benign and malignant masses was searched in PubMed, Cochrane Library, and Embase databases until October 1, 2021. Two authors independently extracted the data. Studies included in the analysis were required to provide data for the construction of a 2 × 2 contingency table to evaluate the diagnostic performance of SUVmax or ADC in differentiating benign and malignant ovarian or adnexal masses. The quality of the enrolled studies was evaluated by Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) instrument, and the meta-analysis was conducted using Stata software version 14.0. Forest plots were generated according to the sensitivity and specificity of SUVmax and ADC, and meta-regression analysis was further used to assess heterogeneity between studies.

Results

A total of 14 studies were finally included in this meta-analysis by gradually excluding duplicate literatures, conference abstracts, guidelines, reviews, case reports, animal studies and so on. The pooled sensitivity and specificity of SUVmax for quantitative differentiation of benign and malignant ovarian or adnexal masses were 0.88 and 0.89, respectively, and the pooled sensitivity and specificity for ADC were 0.87 and 0.80, respectively.

Conclusion

Quantitative SUVmax and ADC values have good diagnostic performance in differentiating benign and malignant ovarian or adnexal masses, and SUVmax has higher accuracy than ADC. Future prospective studies with large sample sizes are needed for the analysis of the role of SUVmax and ADC in the differentiation of benign and malignant ovarian or adnexal masses. 

Added Value of Quantitative Analysis of Diffusion-Weighted Imaging in Ovarian-Adnexal Reporting and Data System Magnetic Resonance Imaging

BACKGROUND

The ovarian-adnexal reporting and data system-magnetic resonance imaging (O-RADS-MRI) score decreases the incidence of indeterminate adnexal masses from 18% to 31% with ultrasound till 10.8% to 12.5% with MRI. Further improvement of this score may be useful to improve patients' management.

PURPOSE

To evaluate the added value of quantitative diffusion-weighted imaging (DWI) in the diagnosis of adnexal masses classified according to the O-RADS-MRI score.

STUDY TYPE

Prospective cohort study with retrospective DWI analysis.

POPULATION

Among 402 recruited patients, surgery was done only in 163 women (median-age: 51 years) with 201 indeterminate adnexal masses, which were included in the final analysis.

FIELD STRENGTH/SEQUENCE

Standardized MRI (1.5 and 3-T) including diffusion and dynamic contrast-enhanced sequences (diffusion-weighted single-shot spin-echo echo-planar imaging) were used.

ASSESSMENT

Two radiologists classified the adnexal masses according to O-RADS-MRI and they were blinded to the pathology report. Two methods of quantitative analysis were applied using region-of-interest apparent-diffusion-coefficient (ROI-ADC) and whole-lesion ADC-histogram (WL-ADC).

STATISTICAL TESTS

Fisher's exact and Mann-Whitney-U tests were used to compare variables among malignant and benign lesions. Receiver-operating-characteristic (ROC) curves were constructed to examine the sensitivity/specificity of each parameter. ROI-ADC and WL-ADC of lesions with O-RADS-MRI score-4 were plotted to identify thresholds of malignant lesions. The improvement of the O-RADS-MRI score after adding these thresholds was assessed by two ROC-curves. A P < 0.05 was considered to be statistically significant.

RESULTS

Fifty-eight of the 201 lesions (28.9%) were malignant. The ROI-ADC and the WL-ADC means of malignant lesions were significantly lower than those of benign lesions. Forty-two lesions (20.9%) had an O-RADS-MRI score-4. In this subgroup, 76% of lesions with ROI-ADC < 1.7 × 10^-3  mm² /sec and WL-ADC < 2.6 × 10^-3  mm² /sec were malignant, whereas only 11.8% with ROI-ADC ≥ 1.7 × 10^-3  mm² /sec or a WL-ADC ≥ 2.6 × 10^-3  mm² /sec were malignant. The overall performance of the O-RADS-MRI score combined with these thresholds was improved.

DATA CONCLUSION

Integrating ADC-thresholds in O-RADS-MRI score-4 may discriminate low-to-intermediate and intermediate-to-high malignancy risk groups.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Indirect comparison of the diagnostic performance of 18F-FDG PET/CT and MRI in differentiating benign and malignant ovarian or adnexal tumors: a systematic review and meta-analysis

Objective

To compare the value of fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT) and magnetic resonance imaging (MRI) in differentiating benign and malignant ovarian or adnexal tumors.

Materials and methods

English articles reporting on the diagnostic performance of MRI or ¹⁸F-FDG PET/CT in identifying benign and malignant ovarian or adnexal tumors published in PubMed and Embase between January 2000 and January 2021 were included in the meta-analysis. Two authors independently extracted the data. If the data presented in the study report could be used to construct a 2 × 2 contingency table comparing ¹⁸F-FDG PET/CT and MRI, the studies were selected for the analysis. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used to evaluate the quality of the included studies. Forest plots were generated according to the sensitivity and specificity of ¹⁸F-FDG PET/CT and MRI.

Results

A total of 27 articles, including 11¹⁸F-FDG PET/CT studies and 17 MRI studies on the differentiation of benign and malignant ovarian or adnexal tumors, were included in this meta-analysis. The pooled sensitivity and specificity for ¹⁸F-FDG PET/CT in differentiating benign and malignant ovarian or adnexal tumors were 0.94 (95% CI, 0.87–0.97) and 0.86 (95% CI, 0.79–0.91), respectively, and the pooled sensitivity and specificity for MRI were 0.92 (95% CI: 0.89–0.95) and 0.85 (95% CI: 0.79–0.89), respectively.

Conclusion

While MRI and ¹⁸F-FDG PET/CT both showed to have high and similar diagnostic performance in the differential diagnosis of benign and malignant ovarian or adnexal tumors, MRI, a promising non-radiation imaging technology, may be a more suitable choice for patients with ovarian or accessory tumors. Nonetheless, prospective studies directly comparing MRI and 18F-FDG PET/CT diagnostic performance in the differentiation of benign and malignant ovarian or adnexal tumors are needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08815-3.

Diffusivity mapping of the ovaries: Variability of apparent diffusion and kurtosis variables over the menstrual cycle and influence of oral contraceptives

PURPOSE

We aimed to investigate whether quantitative diffusivity variables of healthy ovaries vary during the menstrual cycle and to evaluate alterations in women using oral contraceptives (OC).

METHODS

This prospective study (S-339/2016) included 30 healthy female volunteers, with (n = 15) and without (n = 15) intake of OC between 07/2017 and 09/2019. Participants underwent 3T diffusion-weighted MRI (b-values 0-2000 s/mm²) three times during a menstrual cycle (T1 = day 1-5; T2 = day 7-12; T3 = day 19-24). Both ovaries were manually three-dimensionally segmented on b = 1500 s/mm²; apparent diffusion coefficient (ADC) calculation and kurtosis fitting (D_app, K_app) were performed. Differences in ADC, D_app and K_app between time points and groups were compared using repeated measures ANOVA and t-test after Shapiro-Wilk and Brown-Forsythe test for normality and equal variance.

RESULTS

In women with a natural menstrual cycle, ADC and kurtosis variables showed significant changes in ovaries with the dominant follicle between T1 vs T2 and T1 vs T3, whilst no differences were observed between T2 vs T3: ADC ± SD for T1 1.524 ± 0.160, T2 1.737 ± 0.160, and T3 1.747 ± 0.241 μm²/ms (p = 0.01 T2 vs T1; p = 1.0 T2 vs T3, p = 0.003 T3 vs T1); D_app ± SD for T1 2.018 ± 0.140, T2 2.272 ± 0.189, and T3 2.230 ± 0.256 μm²/ms (p = 0.003 T2 vs T1, p = 1.0 T2 vs T3, p = 0.02 T3 vs T1); K_app ± SD for T1 0.614 ± 0.0339, T2 0.546 ± 0.0637, and T3 0.529 ± 0.0567 (p < 0.001 T2 vs T1, p = 0.86 T2 vs T3, p < 0.001 T3 vs T1). No significant differences were found in the contralateral ovaries or in females taking OC.

CONCLUSION

Physiological cycle-dependent changes in quantitative diffusivity variables of ovaries should be considered especially when interpreting radiomics analyses in reproductive women.

Magnetic resonance scoring system for assessment of adnexal masses: added value of diffusion-weighted imaging including apparent diffusion coefficient map

OBJECTIVES

To validate prospectively the ADNEX magnetic resonance (MR) scoring system to assess adnexal masses and to evaluate a new, modified ADNEX MR scoring system that incorporates diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping.

METHODS

Between January 2015 and September 2018, 323 consecutive women with adnexal masses diagnosed on transvaginal ultrasound (TVS) underwent standardized MR imaging (MRI) including diffusion and dynamic contrast-enhanced sequences. Of these, 131 underwent subsequent surgery. For interpretation of the MRI examinations, we applied the five-category ADNEX MR scoring system, along with a modified scoring system including DWI with ADC mapping. For both scoring systems, a score was given for all adnexal masses. Histological diagnosis was considered as the gold standard and lesions were classified as benign or malignant. The difference between the predictive values for diagnosing malignancy of the classical and modified scoring systems was assessed on the basis of the areas under the receiver-operating-characteristics (AUC) curves. The sensitivity and specificity for diagnosing malignancy of each score were also calculated.

RESULTS

Among the 131 women with adnexal mass(es) diagnosed on TVS who underwent MRI and subsequent surgery, the surgery revealed 161 adnexal masses in 126 women; five women had no mass. Histological examination confirmed 161 adnexal masses, of which all had been detected on MRI: 32 malignant tumors, 15 borderline tumors, which were classified as part of the malignant group (n = 47), and 114 benign lesions. The AUC for prediction of a malignant lesion was 0.938 (95% CI, 0.902-0.975) using the classical ADNEX MR scoring system and 0.974 (95% CI, 0.953-0.996) using the modified scoring system. Pairwise comparison of these AUCs revealed a significant difference (P = 0.0032). The sensitivity and specificity for diagnosing malignancy with an ADNEX MR score of 4 or more were 95.5% and 86.6%, respectively, using the classic scoring system, and 95.7% and 93.3%, respectively, using the modified scoring system.

CONCLUSION

DWI with ADC mapping could be integrated into the ADNEX MR scoring system to improve specificity, thereby potentially optimizing clinical management by avoiding unnecessary surgery. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Analysis of magnetic resonance imaging features of ovarian thecoma

To investigate the magnetic resonance imaging (MRI) findings in ovarian thecoma and improve preoperative diagnostic accuracy.Retrospective analysis was performed on 45 patients with surgically and pathologically confirmed ovarian thecoma. Patients were grouped into those with maximum lesion diameter ≥5 cm and <5 cm. Diagnostic scores (up to 6 points) were evaluated on the basis of MRI performance.The ≥5 cm group contained 36 cases (cystic necrosis, 32 cases) with the following findings: T1WI: isointense signal, 22 cases; slightly hypointense signal, 14 cases; T2WI: isointense signal, 6 cases; slightly hypointense signal, 21 cases; slightly hyperintense signal, 9 cases; Diffusion-weighted imaging (DWI): hyperintense signal, 23 cases; mixed hyperintense signal, 13 cases; slight enhancement on dynamic enhanced scans; pelvic fluid accumulation, 31 cases. The diagnostic score evaluations yielded 6 points in 31 cases, 5 points in 1 case, 4 points in 2 cases, and 3 points in 2 cases. The <5 cm group contained 9 cases (cystic necrosis, 3 cases) with the following findings: T1WI: isointense signal, 3 cases; slightly hypointense signal, 6 cases; T2WI: isointense signal, 2 cases; slightly hypointense signal, 4 cases; slightly hyperintense signal, 3 cases; DWI, hyperintense signal; slight enhancement in 8 cases and significant enhancement in 1 case; pelvic fluid accumulation, 4 cases. The diagnostic score evaluations yielded 6 points in 3 cases, 5 points in 1 case, 4 points in 4 cases, and 3 points in 1 case. (iii) Incidence of pelvic fluid accumulation and cystic necrosis differed depending on the size of the lesion (P = .007, .000).Larger lesions show hyperintense or mixed hyperintense signals on DWI along with pelvic fluid and cystic necrosis; whereas, smaller lesions show a hyperintense signal on DWI, cystic necrosis is rare. MRI characteristics along with the patient age and laboratory findings can improve the accuracy of preoperative diagnosis of these lesions.

Ovarian solid tumors: MR imaging features with radiologic-pathologic correlation

Ovarian solid tumors have variable histological types including benign and malignant tumors. In addition, non-neoplastic lesions sometimes show a tumor-like appearance. It is important to differentiate benign from malignant tumors. In general, low signal intensity (SI) on T2-weighted imaging (T2WI), low SI on diffusion-weighted imaging (DWI), and gradual increased pattern on dynamic contrast-enhanced magnetic resonance (MR) imaging are known to be suggestive of a benign tumor. Conversely, there are some cases in which these rules do not apply. We should, therefore, strive for a greater understanding of these exceptional cases. Several tumors show characteristic findings on MR imaging reflecting pathologic features, which leads to the correct diagnosis. Additionally, MR imaging provides important information other than the nature of tumors, such as secondary uterine changes. Furthermore, clinical findings and laboratory examination data also help in determining the correct diagnosis.

Value of magnetic resonance spectroscopy in assessment of adnexal lesions

Background

The purpose of this study is to investigate the role of proton MR spectroscopy (1H-MRS) in the characterization and diagnosis of ovarian lesions.

Results

From October 2015 to October 2017, a total of 57 female patients (65 adnexal lesions; 8 cases were bilateral) were included. The examined lesions were classified according to their histopathological findings, (37 (57%) benign lesions, 4 (6%) borderline lesions, and 24 (37%) malignant lesions). The mean choline/creatinine (CHO/Cr) ratio was 1.29 ± 0.98 SD for malignant lesions, while the mean value in borderline lesions was 0.63 ± 0.15 SD, and the mean value for the benign lesions was 0.65 ± 0.34. Therefore, the mean CHO/Cr ratio was much higher in malignant than in benign lesions, which was statistically significant (P ≤ 0.001) as well as between the borderline and invasive lesions (P = 0.05), but not between the benign and borderline lesions. The diagnostic performance of conventional MRI in diagnosing adnexal lesions was 100%, specificity was 76%, and accuracy was 86%. However, MRS individual diagnostic performances are the following: sensitivity 89%, specificity, and 100% with an accuracy of 95%.

Conclusion

MRS proved to be an accurate and efficient method for the analysis of adnexal lesions and in differentiation between benign and malignant tumors.

MR imaging in discriminating between benign and malignant paediatric ovarian masses: a systematic review

OBJECTIVES

The use of magnetic resonance (MR) imaging in differentiation between benign and malignant adnexal masses in children and adolescents might be of great value in the diagnostic workup of sonographically indeterminate masses, since preserving fertility is of particular importance in this population. This systematic review evaluates the diagnostic value of MR imaging in children with an ovarian mass.

METHODS

The review was made according to the PRISMA Statement. PubMed and EMBASE were systematically searched for studies on the use of MR imaging in differential diagnosis of ovarian masses in both adult women and children from 2008 to 2018.

RESULTS

Sixteen paediatric and 18 adult studies were included. In the included studies, MR imaging has shown good diagnostic performance in differentiating between benign and malignant ovarian masses. MR imaging techniques including diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) imaging seem to further improve the diagnostic performance.

CONCLUSION

The addition of DWI with apparent diffusion coefficient (ADC) values measured in enhancing components of solid lesions and DCE imaging may further increase the good diagnostic performance of MR imaging in the pre-operative differentiation between benign and malignant ovarian masses by increasing specificity. Prospective age-specific studies are needed to confirm the high diagnostic performance of MR imaging in children and adolescents with a sonographically indeterminate ovarian mass.

KEY POINTS

• MR imaging, based on several morphological features, is of good diagnostic performance in differentiating between benign and malignant ovarian masses. Sensitivity and specificity varied between 84.8 to 100% and 20.0 to 98.4%, respectively. • MR imaging techniques like diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) imaging seem to improve the diagnostic performance. • Specific studies in children and adolescents with ovarian masses are required to confirm the suggested increased diagnostic performance of DWI and DCE in this population.

Apparent diffusion coefficients measured using different regions of interest in differentiating borderline from malignant ovarian tumors

Background

Apparent diffusion coefficients (ADCs) measured using different regions of interest (ROIs) are widely used in differentiating ovarian tumors.

Purpose

To evaluate the diagnostic performance of ADCs with different ROIs in differentiating borderline ovarian tumors (BOTs) from malignant ovarian tumors (MOTs).

Material and Methods

Thirty-five BOTs and 54 MOTs who underwent diffusion-weighted magnetic resonance imaging (MRI) were evaluated retrospectively. ADC values were independently measured using five ROI methods: round; rectangle; hot-spot; edge drawing; and five sample ROIs. The inter- and intraclass correlation coefficients (ICCs), one-way analysis of variance, receiver operating characteristic curve analysis, and unpaired t-tests were used to perform the statistical analyses.

Results

The measurement reproducibility of the minimum ADC and mean ADC values were good or excellent for BOTs and MOTs (ICC = 0.70–0.95). The minimum and mean ADC value by the edge drawing ROI were significantly higher than those of the other ROI methods (both P < 0.05). The area under the curve (AUC) of the minimum ADC value was less than that of the mean ADC value from the five ROI methods, whereas the AUCs of the mean ADC values from the round ROI and five sample ROIs were significantly larger than those of the other ROI methods ( P < 0.05). The minimum and mean ADC values from the five ROI methods showed significant differences between BOTs and MOTs (all P < 0.05).

Conclusion

The ROI shape influences the diagnostic performance of ADC value for differentiating BOTs from MOTs. The mean ADC values from the round ROI and five sample ROIs have better diagnostic efficiency.

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.

Utility of DWI with quantitative ADC values in ovarian tumors: a meta-analysis of diagnostic test performance

Background Diffusion-weighted imaging (DWI) and quantitative apparent diffusion coefficient (ADC) values are widely used in the differential diagnosis of ovarian tumors. Purpose To assess the diagnostic performance of quantitative ADC values in ovarian tumors. Material and Methods PubMed, Embase, the Cochrane Library, and local databases were searched for studies assessing ovarian tumors using quantitative ADC values. We quantitatively analyzed the diagnostic performances for two clinical problems: benign vs. malignant tumors and borderline vs. malignant tumors. We evaluated diagnostic performances by the pooled sensitivity and specificity values and by summary receiver operating characteristic (SROC) curves. Subgroup analyses were used to analyze study heterogeneity. Results From the 742 studies identified in the search results, 16 studies met our inclusion criteria. A total of ten studies evaluated malignant vs. benign ovarian tumors and six studies assessed malignant vs. borderline ovarian tumors. Regarding the diagnostic accuracy of quantitative ADC values for distinguishing between malignant and benign ovarian tumors, the pooled sensitivity and specificity values were 0.91 and 0.91, respectively. The area under the SROC curve (AUC) was 0.96. For differentiating borderline from malignant tumors, the pooled sensitivity and specificity values were 0.89 and 0.79, and the AUC was 0.91. The methodological quality of the included studies was moderate. Conclusion Quantitative ADC values could serve as useful preoperative markers for predicting the nature of ovarian tumors. Nevertheless, prospective trials focused on standardized imaging parameters are needed to evaluate the clinical value of quantitative ADC values in ovarian tumors.

Magnetic resonance imaging of pediatric adnexal masses and mimics

Evaluation of adnexal masses in children and adolescents relies on imaging for appropriate diagnosis and management. Pelvic MRI is indicated and adds value for all adnexal masses when surgery is considered or when ultrasound findings are indeterminate. Specifically, features on MR imaging can help distinguish between benign and malignant lesions, which not only influences the decision between surgery and conservative treatment, but also the type of surgery to be performed, including potential use of fertility-sparing approaches with minimally invasive techniques. Larger size, younger age, presentation with precocious puberty or virilization, restricted diffusion in a solid mass, and rapid and strong enhancement of solid components are all features concerning for malignancy. In addition, distinctive MR imaging features of adnexal masses, combined with clinical and laboratory biomarkers, might suggest a specific histological diagnosis.

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.

Computed tomography and magnetic resonance imaging features of ovarian fibrothecoma

The aim of the present study was to investigate the imaging characteristics of ovarian fibrothecoma. The cases of 25 female patients with pathologically confirmed ovarian fibrothecomas were retrospectively reviewed. Tumor location, size, density, signal intensity, cystic degeneration, calcification, enhancement pattern and ascites were assessed by computed tomography (CT) (n=20) and magnetic resonance imaging (MRI) (n=5). Clinical and histological features were also evaluated. The results revealed that 23 (92.0%) patients were postmenopausal, with a mean age ± standard deviation (SD) of 60.7±10.8 years old. All 25 tumors were unilateral and a thickened endometrium was observed in 7 (28.0%) patients. In total, 24 (96.0%) tumors appeared to have well-defined boundaries, with 1 (4%) tumor exhibiting an obscure boundary. Tumors had a mean size of 9.8±5.3 cm. Solid and predominantly solid masses were found in 16 cases (64.0%), and cystic and predominantly cystic masses were found in 9 patients (36.0%). Solid regions of masses exhibited hypodensity or isodensity in 24 patients (96.0%), with 1 patient (4.0%) exhibiting hyperdensity. The mean CT value (± SD) was 44.2±12.8 HU (range, 31-79HU) in unenhanced images. All masses exhibited isointensity or slight hypointensity on T1-weighted imaging, and tumor parenchyma also exhibited slight hypointensity or isointensity on T2-weighted imaging compared with the myometrium, with or without areas of patchy hyperintensity. Contrast-enhanced CT or MRI scans were performed on 19 patients, and the solid components (94.7%) exhibited mild to moderate enhancement in 18 patients and 1 patient (5.3%) exhibited intense enhancement. Tumor size was positively correlated with the tumor cystic degeneration (r=0.77, P<0.001) and ascites (r=0.41, P<0.001). Therefore, ovarian fibrothecoma typically presents as solid or predominant solid masses with clear boundaries; the parenchyma of the tumor exhibits isodensity on CT scans, slight hypointensity or isointensity on MRI and mild enhancement following contrast-medium injection. The thickened endometrium observed in postmenopausal woman may also be a valuable imaging feature.

Diagnostic accuracy of DWI in patients with ovarian cancer: A meta-analysis

BACKGROUND

Diffusion weighted imaging (DWI) is recently developed for identifying different malignant tumors. In this article the diagnostic accuracy of DWI for ovarian cancer was evaluated by synthesis of published data.

METHODS

A comprehensive literature search was conducted in PubMed/MEDLINE and Embase databases on the diagnostic performance of DWI for ovarian cancer published in English. Methodological quality was evaluated following Quality Assessment for Studies of Diagnostic Accuracy 2 (QUADAS 2) tool. We adopted the summary receiver operating characteristic (SROC) curve to assess the DWI accuracy.

RESULTS

Twelve studies including 1142 lesions were analyzed in this meta-analysis to estimate the pooled Sen (sensitivity), Spe (specificity), PLR (positive likelihood ratio), NLR (negative likelihood ratio), and construct SROC (summary receiver operating characteristics) curve. The pooled Sen and Spe were 0.86 (95% confidence interval [CI], 0.83-0.89) and 0.81 (95%CI, 0.77-0.84), respectively. The pooled PLR and pooled NLR were 5.07 (95%CI, 3.15-8.16) and 0.17 (95%CI, 0.10-0.30), respectively. The pooled diagnostic odds ratio (DOR) was 35.23 (95%CI, 17.21-72.14). The area under the curve (AUC) was 0.9160.

CONCLUSION

DWI had moderately excellent diagnostic ability for ovarian cancer and promised to be a helpful diagnostic tool for patients of ovarian cancer.

The distribution of the apparent diffusion coefficient as an indicator of the response to chemotherapeutics in ovarian tumour xenografts

Diffusion-weighted magnetic resonance imaging (DW-MRI) was used to evaluate the effects of single-agent and combination treatment regimens in a spheroid-based animal model of ovarian cancer. Ovarian tumour xenografts grown in non-obese diabetic/severe-combined-immunodeficiency (NOD/SCID) mice were treated with carboplatin or paclitaxel, or combination carboplatin/paclitaxel chemotherapy regimens. After 4 weeks of treatment, tumours were extracted and underwent DW-MRI, mechanical testing, immunohistochemical and gene expression analyses. The distribution of the apparent diffusion coefficient (ADC) exhibited an upward shift as a result of each treatment regimen. The 99-th percentile of the ADC distribution (“maximum ADC”) exhibited a strong correlation with the tumour size (r² = 0.90) and with the inverse of the elastic modulus (r² = 0.96). Single-agent paclitaxel (n = 5) and combination carboplatin/paclitaxel (n = 2) treatment regimens were more effective in inducing changes in regions of higher cell density than single-agent carboplatin (n = 3) or the no-treatment control (n = 5). The maximum ADC was a good indicator of treatment-induced cell death and changes in the extracellular matrix (ECM). Comparative analysis of the tumours’ ADC distribution, mechanical properties and ECM constituents provides insights into the molecular and cellular response of the ovarian tumour xenografts to chemotherapy. Increased sample sizes are recommended for future studies. We propose experimental approaches to evaluation of the timeline of the tumour’s response to treatment.

An update on the role of PET/CT and PET/MRI in ovarian cancer

This review article summarizes the role of PET/CT and PET/MRI in ovarian cancer. With regard to the diagnosis of ovarian cancer, the presence of FDG uptake within the ovary of a postmenopausal woman raises the concern for ovarian cancer. Multiple studies show that FDG PET/CT can detect lymph node and distant metastasis in ovarian cancer with high accuracy and may, therefore, alter the management to obtain better clinical outcomes. Although PET/CT staging is superior for N and M staging of ovarian cancer, its role is limited for T staging. Additionally, FDG PET/CT is of great benefit in evaluating treatment response and has prognostic value in patients with ovarian cancer. FDG PET/CT also has value to detect recurrent disease, particularly in patients with elevated serum CA-125 levels and negative or inconclusive conventional imaging test results. PET/MRI may beneficial for tumor staging because MRI has higher soft tissue contrast and no ionizing radiation exposure compared to CT. Some non-FDG PET radiotracers such as ¹⁸F-fluorothymidine (FLT) or ¹¹C-methionine (MET) have been studied in preclinical and clinical studies as well and may play a role in the evaluation of patients with ovarian cancer.

Role of Imaging Tools for the Diagnosis of Borderline Ovarian Tumors: A Systematic Review and Meta-Analysis

Borderline ovarian tumors (BOTs) have a low malignant potential and occur most often in young women. Its preoperative diagnosis can improve surgical strategy and reproductive approach. This study systematically reviews the literature for the accuracy of transvaginal ultrasound (TVUS), magnetic resonance (MRI), and computed tomography (CT) in the diagnostic of BOTs. We conducted a search in PubMed/Medline of articles in English from the last 5 years and included 14 studies for systematic review, 9 of them in the meta-analysis. The pooled sensibility and specificity was respectively 77.0% and 83.0% for TVUS (5 studies) and 85% and 74% for MRI (4 studies) in differentiating benign from malignant BOTs. CT and positron emission tomography (PET)-CT techniques were heterogeneous between studies, so a meta-analysis was not performed for the 4 studies on CT and PET-CT. However, these 4 studies have also shown a high accuracy in differentiating BOTs from malignant ovarian cancers.

Interpreting body MRI cases: what you need to know to get started

Interpreting body MRI cases can seem overwhelming to an uninitiated radiologist. The standard study includes a variety of pulse sequences, the names of which vary depending on the MR vendor. Pulse sequences may be displayed haphazardly on the picture archiving and communication system (PACS), frequently not synchronized with the imaging protocol. Adding to the complexity is the use of different gadolinium-based contrast agents, which may affect the timing and diagnostic yield of each sequence. The following introductory primer for interpreting body MRI cases is meant to create a basic framework for efficiently reviewing body MRI cases to provide high quality interpretations, fully utilizing the diagnostic information of the modality. There are 4 components that need to be mastered when interpreting body MRI cases including: (1) recognizing the key sequences in a basic body MRI protocol, (2) learning how to best display the key pulse sequences on PACS, (3) understanding the technique and clinical utility of each sequence and learning how to utilize sequences to be an "MR Pathologist", and (4) understanding the key features of the different gadolinium based contrast agents.

Diffusion weighted imaging for the differential diagnosis of benign vs. malignant ovarian neoplasms

In order to assess the diagnostic accuracy of diffusion weighted imaging (DWI) in differentiating between benign and malignant ovarian neoplasms, a systemic meta-analysis was conducted. Relevant studies were retrieved from scientific literature databases, including the PubMed, Wiley, EBSCO, Ovid, Web of Science, Wanfang, China National Knowledge Infrastructure and VIP databases. Following a multi-step screening and study selection process, the relevant data was extracted for use in the present study. Statistical analyses were performed using Meta-disc software version 1.4 and STATA statistical software version 12.0. A total of 285 articles were retrieved from the database searches. Following a careful screening process, 10 case-control studies were selected for the present meta-analysis. The 10 studies investigated the efficacy of DWI in diagnosing ovarian neoplasms, and included a combined total of 1,159 subjects, of which 559 patients had malignant lesions and 600 had benign lesions. The results showed that the pooled sensitivity, pooled specificity, pooled positive likelihood ratio, pooled negative likelihood ratio, pooled diagnostic odds ratio (DOR) and area under the curve of the summary receiver operating characteristics curve of DWI for differentiating between benign and malignant ovarian neoplasms were 0.93, 0.89, 7.58, 0.10, 85.33 and 0.95, respectively. A subgroup analysis based on ethnicity revealed no significant difference between Asians and Caucasians. Another subgroup analysis by magnetic resonance imaging (MRI) type showed that the DORs for GE Healthcare Life Sciences and Siemens AG machines were 100.76 [95% confidence interval (CI), 65.28-155.53] and 30.85 (95% CI, 10.40-91.53), respectively; this indicates that the diagnostic efficiency of the GE Healthcare Life Sciences MRI is superior compared with the Siemens AG MRI. The DWI demonstrated an excellent diagnostic performance in discriminating between benign and malignant ovarian neoplasms, and predicted the surgical outcome in ovarian neoplasms.

The Value of Diffusion-Weighted Imaging in the Differential Diagnosis of Ovarian Lesions: A Meta-Analysis

OBJECTIVES

The ability of contrast-enhanced MRI to distinguish between malignant and benign ovarian masses is limited. The aim of this meta-analysis is to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in differentiating malignant from benign ovarian masses.

METHODS

A comprehensive literature search was performed in several authoritative databases to identify relevant articles. The weighted mean difference (WMD) and corresponding 95% confidence interval (95% CI) were calculated. We also used subgroup analysis to analyze study heterogeneity, and evaluated publication bias.

RESULTS

The meta-analysis is based on 21 studies, which reported the findings for 731 malignant and 918 benign ovarian masses. There was no significant difference in apparent diffusion coefficient (ADC) values for DWI between benign and malignant lesions (WMD = 0.22, 95% CI = -0.02-0.47, p = 0.08). Subgroup analysis by benign tumor type revealed higher ADC values (or a trend toward higher values) for cysts, cystadenomas and other benign tumors compared to malignant masses (cyst: WMD = 0.54, 95% CI = -0.05-1.12, p = 0.07; cystadenoma: WMD = 0.73, 95% CI = 0.38-1.07, p < 0.0001; other benign tumor: WMD = 0.16, 95% CI = -0.13-0.46, p = 0.28). On the other hand, lower ADC values (or a trend toward lower values) were observed for endometrioma and teratoma compared to malignant masses (endometrioma: WMD = -0.09, 95% CI = -0.47-0.29, p = 0.64; teratoma: WMD = -0.49, 95% CI = -0.85-0.12, p = 0.009). Subgroup analysis by mass property revealed higher ADC values in cystic tumor types than in solid types for both benign and malignant tumors. Significant study heterogeneity was observed. There was no notable publication bias.

CONCLUSIONS

Quantitative DWI is not a reliable diagnostic method for differentiation between benign and malignant ovarian masses. This knowledge is essential in avoiding misdiagnosis of ovarian masses.

MR imaging of ovarian masses: classification and differential diagnosis

OBJECTIVE

We propose a Magnetic Resonance Imaging (MRI) guided approach to differential diagnosis of ovarian tumours based on morphological appearance.

BACKGROUND

Characterization of ovarian lesions is of great importance in order to plan adequate therapeutic procedures, and may influence patient's management. Optimal assessment of adnexal masses requires a multidisciplinary approach, based on physical examination, laboratory tests and imaging techniques. Primary ovarian tumours can be classified into three main categories according to tumour origin: epithelial, germ cell and sex cord-stromal tumours. Ovarian neoplasms may be benign, borderline or malignant. Using an imaging-guided approach based on morphological appearance, we classified adnexal masses into four main groups: unilocular cyst, multilocular cyst, cystic and solid, predominantly solid. We describe MR signal intensity features and enhancement behaviour of ovarian lesions using pathologically proven examples from our institution.

CONCLUSION

MRI is an essential problem-solving tool to determine the site of origin of a pelvic mass, to characterize an adnexal mass, and to detect local invasion. The main advantages of MRI are the high contrast resolution and lack of ionizing radiation exposure. Although different pathological conditions may show similar radiologic manifestations, radiologists should be aware of MRI features of ovarian lesions that may orientate differential diagnosis.

TEACHING POINTS

• Diagnostic imaging plays a crucial role in detection, characterization and staging of adnexal masses. • Characterization of an ovarian lesion may influence patient's management. • Different pathological conditions may have similar radiologic manifestations. • Non-neoplastic lesions should always be taken into consideration.

Functional MR Imaging in Gynecologic Cancer

Dynamic-contrast enhanced (DCE) and diffusion-weighted (DW) MR imaging are invaluable in the detection, staging, and characterization of uterine and ovarian malignancies, for monitoring treatment response, and for identifying disease recurrence. When used as adjuncts to morphologic T2-weighted (T2-W) MR imaging, these techniques improve accuracy of disease detection and staging. DW-MR imaging is preferred because of its ease of implementation and lack of need for an extrinsic contrast agent. MR spectroscopy is difficult to implement in the clinical workflow and lacks both sensitivity and specificity. If used quantitatively in multicenter clinical trials, standardization of DCE- and DW-MR imaging techniques and rigorous quality assurance is mandatory.

Comparison between borderline ovarian tumors and carcinomas using semi-automated histogram analysis of diffusion-weighted imaging: focusing on solid components

PURPOSE

This study aimed to evaluate whether histogram analysis of the apparent diffusion coefficient (ADC) of a solid tumor component could distinguish borderline ovarian tumors from ovarian carcinoma.

MATERIALS AND METHODS

Sixteen pathologically proven borderline tumors and 21 carcinomas were retrospectively examined. Magnetic resonance (1.5-T) image data sets were coregistered, and the solid components of each tumor were semiautomatically segmented. ADC histograms of the solid components were extracted; modes, minimums, means, and 10th, 25th, 50th, 75th, and 90th percentiles of the histograms were compared between the two tumor types, and receiver-operating characteristic (ROC) analysis was performed.

RESULTS

The mode, minimum, mean, 10th, 25th, 50th, and 75th percentile ADC values of solid components of borderline tumors were significantly larger than those of carcinomas. Among these, the 10th percentile values had the lowest p value (p = 0.0003). At ROC analysis, the area under the curve (AUC) in the 10th percentile was the greatest (0.854), and the best cutoff value in the 10th percentile provided the highest specificity (93.8 %).

CONCLUSIONS

ADC histograms of solid tumor components facilitated the distinction between borderline ovarian tumors and carcinoma. The 10th percentile ADC values had the best diagnostic performance.

Value of diffusion-weighted imaging combined with conventional magnetic resonance imaging in the diagnosis of thecomas/fibrothecomas and their differential diagnosis with malignant pelvic solid tumors

Background

Our study aims to determine the value of diffusion-weighted imaging (DWI) combined with conventional magnetic resonance imaging (MRI) in the diagnosis of thecomas/fibrothecomas and their differential diagnosis with malignant pelvic solid tumors.

Methods

In total, 36 thecomas/fibrothecomas and 40 malignant pelvic solid tumors were included in our study. All patients underwent 1.5 T conventional MRI and DWI examinations except one patient with a fibrothecoma in whom DWI examination was not performed. The clinical features and characteristics of conventional MRI and DWI of these two groups were analyzed. Apparent diffusion coefficient (ADC) values were measured and compared between groups. Univariate analysis, multivariate logistic regression analysis, and the receiver operating characteristic curve were used for statistical analysis.

Results

All the thecomas/fibrothecomas showed isointensity on T1 weighted imaging (T1WI) and 77.8 % (28/36) lesions showed hypo- to isointensity on T2 weighted imaging (T2WI). After administration of contrast medium, 94.4 % (34/36) tumors appeared as minor to mild enhancement. On DWI, they showed a diversity of low to very high signal intensity. All malignant pelvic masses manifested as hyperintensity on T2WI and 87.5 % (35/40) tumors showed very high signal (grade 3) on DWI. Higher area under the curve (AUC) and specificity could be achieved by using the lowest ADC value than the mean ADC value. Multivariate logistic regression analysis showed that shape, signal intensity on T2WI, capsule, and the lowest ADC value were the important indicators in discriminating thecomas/fibrothecomas from malignant pelvic solid tumors.

Conclusions

The combination of DWI and conventional MRI is of great value in the diagnosis of thecomas/fibrothecomas and their differential diagnosis with malignant pelvic solid tumors.

Role of diffusion-weighted magnetic resonance imaging in differentiating malignancies from benign ovarian tumors

OBJECTIVE

We conducted a case-control study to evaluate the diagnostic values of computed tomography (CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) in differentiating malignancies from benign ovarian tumors and a meta-analysis to further confirm our results on DW-MRI.

METHODS

Totally 64 patients pathologically confirmed as ovarian cancer were included in this study. CT scan and DWI-MRI were performed and analyzed to get compared with pathological results, thereby assessing their accuracy, sensitivity and specificity. Meta-analysis was conducted by database searching and strict eligibility criteria, using STATA 12.0 (Stata Corp, College Station, TX, USA) software.

RESULTS

The accuracy, sensitivity, specificity, positive predictive value and negative predictive value for diagnosis of ovarian cancer in CT were 81.82%, 84.48%, 76.67%, 87.50% and 71.88%, respectively; those in DW-MRI were 89.77%, 93.10%, 83.33%, 91.53% and 86.21%, respectively. The Kappa coefficient of DW-MRI (K = 0.771) compared with pathological results was higher than CT (K = 0.602). The average apparent diffusion coefficient values of DW-MRI in diagnosis of benign and malignant ovarian tumors suggested statistically significant difference (1.325 ± 0.269×10(-3) mm(2)/s vs. 0.878 ± 0.246×10(-3) mm(2)/s, P < 0.001). Meta-analysis results showed that the combined sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of DW-MRI in discriminating benign versus malignant ovarian tumors were 0.93, 0.88, 7.70, 0.08 and 101.24, respectively. The area under the summary receiver operating characteristic curve was 0.95.

CONCLUSIONS

Both CT and DW-MRI were of great diagnostic value in differentiating malignancies from benign ovarian tumors, while DW-MRI was superior to CT with higher accuracy, sensitivity and specificity.

Diffusion-weighted MRI of epithelial ovarian cancers: correlation of apparent diffusion coefficient values with histologic grade and surgical stage

OBJECTIVE

The purpose of this article is to correlate the apparent diffusion coefficient (ADC) values of epithelial ovarian cancers with histologic grade and surgical stage.

MATERIALS AND METHODS

We enrolled 43 patients with pathologically proven epithelial ovarian cancers for this retrospective study. All patients underwent preoperative pelvic magnetic resonance imaging (MRI) including diffusion-weighted images with b value of 0 and 1000 s/mm2 at 3.0-T unit. The mean ADC values of the solid portion of the tumor were measured and compared among different histologic grades and surgical stages.

RESULTS

The mean ADC values of epithelial ovarian cancers differed significantly between grade 1 (well-differentiated) and grade 2 (moderately-differentiated) (P=0.013) as well as between grade 1 and grade 3 (poorly-differentiated) (P=0.01); however, no statistically significant difference existed between grade 2 and grade 3 (P=0.737). The receiver-operating characteristic analysis indicated that a cutoff ADC value of less than or equal to 1.09×10(-3)mm2/s was associated with 94.4% sensitivity and 85.7% specificity in distinguishing grade 1 and grade 2/3 cancer. The difference in mean ADC values was statistically significant for early stage (FIGO stage I) and advanced stage (FIGO stage II-IV) cancer (P=0.011). The interobserver agreement for the mean ADC values of epithelial ovarian cancers was excellent.

CONCLUSION

The mean ADC values of the solid portion of epithelial ovarian cancers negatively correlated to histologic grade and surgical stage. The mean ADC values may be useful imaging biomarkers for assessment of tumor grade of epithelial ovarian cancer.

Management of epithelial ovarian cancer from diagnosis to restaging: an overview of the role of imaging techniques with particular regard to the contribution of 18F-FDG PET/CT

Epithelial ovarian carcinoma is a major form of cancer affecting women in the western world. The silent nature of this disease results in late presentation at an advanced stage in many patients. It is therefore important to assess the role of imaging techniques in the management of these patients. This article presents a review of the literature on the role of (18)F-FDG-PET/CT in the different stages of management of epithelial ovarian cancer. Moreover, a comparison with other imaging techniques has been made and the relationship between (18)F-PET/CT and the assay of serum CA-125 levels has been discussed.

Magnetic resonance and diffusion-weighted imaging in categorization of uterine sarcomas: correlation with pathological findings

OBJECTIVES

We investigated the utility of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the categorization of uterine sarcoma (US) and compared them with pathological findings.

METHODS

The baseline and MRI characteristics were recorded and compared across the subtypes of USs.

RESULTS

There were no differences in the conventional or DWI signals among the four subtypes of US, except in the heterogeneity of T2-weighted imaging. A difference in the mean apparent diffusion coefficient value for USs and uterine fibroids differed significantly (P=.019).

CONCLUSIONS

MRI characteristics showed no specific differences between any subtypes of US.