Diagnostic accuracy of the apparent diffusion coefficient in differentiating benign from malignant uterine endometrial cavity lesions: initial results. Eur Radiol. 2008;18:384-389. [PMID: 17917730 DOI: 10.1007/s00330-007-0769-9]

Evaluation of multiplexed sensitivity encoding diffusion-weighted imaging in detecting uterine lesions: Image quality optimization

PURPOSE

To compare the image quality of multiplexed sensitivity-encoding diffusion-weighted imaging (MUSE-DWI) and single-shot echo-planar imaging (SS-EPI-DWI) techniques in uterine MRI.

METHODS

Eighty-eight eligible patients underwent MUSE-DWI and SS-EPI-DWI examinations simultaneously using a 3.0 T MRI system. Two radiologists independently performed quantitative and qualitative analysis of the two groups of images using a double-blind method. The weighted Kappa test was used to evaluate the interobserver agreement. Wilcoxon's rank sum test was used for qualitative parameters, and paired t-test was used for quantitative parameters. Spearman rank correlation analysis was used to obtained correlation between pathological results and mean apparent diffusion coefficient (ADC) value.

RESULTS

The qualitative and quantitative analysis of the images by the two radiologists were in good or excellent agreement, with weighted kappa value ranging from 0.636 to 0.981. The scores of total subjective image quality (15.4 ± 0.99) and signal-to-noise ratio (158.99 ± 60.71) of MUSE-DWI were significantly higher than those of SS-EPI-DWI (12.93 ± 1.62 P < 0.001; 130.23 ± 48.29 P < 0.05). It effectively reduced image distortion and artifact, and had better lesion conspicuity. There was no significant difference in contrast-to-noise ratio score and average ADC values between the two DWI sequences. The average ADC values of the two DWI sequences were highest in the normal uterus group and lowest in the endometrial cancer group, with statistically significant differences among groups (P < 0.01). In addition, the average ADC values of the two DWI sequences were negatively correlated with the type of lesions, decreasing with the malignancy of the lesions (r = -0.805 P < 0.01, r = -0.815 P < 0.01).

CONCLUSION

Compared to SS-EPI-DWI, MUSE-DWI can significantly reduce distortion, artifacts, and fuzziness in MRI of uterine lesions, which is more conducive to lesion detection.

Clinical and multiparametric MRI features for differentiating uterine carcinosarcoma from endometrioid adenocarcinoma

INTRODUCTION

The purpose of our study was to differentiate uterine carcinosarcoma (UCS) from endometrioid adenocarcinoma (EAC) by the multiparametric magnetic resonance imaging (MRI) features.

METHODS

We retrospectively evaluated clinical and MRI findings in 17 patients with UCS and 34 patients with EAC proven by histologically. The following clinical and pathological features were evaluated: post- or pre-menopausal, clinical presentation, invasion depth, FIGO stage, lymphaticmetastasis. The following MRI features were evaluated: tumor dimension, cystic degeneration or necrosis, hemorrhage, signal intensity (SI) on T2-weighted images (T2WI), relative SI of lesion to myometrium on T2WI, T1WI, DWI, ADCmax, ADCmin, ADCmean (RSI-T2, RSI-T1, RSI-DWI, RSI-ADCmax, RSI-ADCmin, RSI-ADCmean), ADCmax, ADCmin, ADCmean, the maximum, minimum and mean relative enhancement (RE) of lesion to myometrium on the arterial and venous phases (REAmax, REAmin, REAmean, REVmax, REVmin, REVmean). Receiver operating characteristic (ROC) analysis and the area under the curve (AUC) were used to evaluate prediction ability.

RESULTS

The mean age of UCS was higher than EAC. UCS occurred more often in the postmenopausal patients. UCS and EAC did not significantly differ in depth of myometrial invasion, FIGO stage and lymphatic metastasis. The anterior-posterior and transverse dimensions were significantly larger in UCS than EAC. Cystic degeneration or necrosis and hemorrhage were more likely occurred in UCS. The SI of tumor on T2WI was more heterogeneous in UCS. The RSI-T2, ADCmax, ADCmean, RSI-ADCmax and RSI-ADCmean of UCS were significantly higher than EAC. The REAmax, REAmin, REAmean, REVmax, REVmin and REVmean of UCS were all higher than EAC. The AUCs were 0.72, 0.71, 0.86, 0.96, 0.89, 0.84, 0.73, 0.97, 0.88, 0.94, 0.91, 0.69 and 0.80 for the anterior-posterior dimension, transverse dimension, RSI-T2, ADCmax, ADCmean, RSI-ADCmax, RSI-ADCmean, REAmax, REAmin, REAmean, REVmax, REVmin and REVmean, respectively. The AUC was 0.997 of the combined of ADCmax, REAmax and REVmax. Our study showed that ADCmax threshold value of 789.05 (10-3mm2/s) can differentiate UCS from EAC with 100% sensitivity, 76.5% specificity, and 0.76 AUC, REAmax threshold value of 0.45 can differentiate UCS from EAC with 88.2% sensitivity, 100% specificity, and 0.88 AUC.

CONCLUSION

Multiparametric MRI features may be utilized as a biomarker to distinguish UCS from EAC.

Can the ADC Value Be Used as an Imaging "Biopsy" in Endometrial Cancer?

BACKGROUND

The tumor histological grade is closely related to the prognosis of patients with endometrial cancer (EC). Multiparametric MRI, including diffusion-weighted imaging (DWI), provides information about the cellular density that may be useful to differentiate between benign and malignant uterine lesions. However, correlations between apparent diffusion coefficient (ADC) values and histopathological grading in endometrial cancer remain controversial.

MATERIAL AND METHODS

We retrospectively evaluated 92 patients with endometrial cancers, including both endometrioid adenocarcinomas (64) and non-endometrioid adenocarcinomas (28). All patients underwent DWI procedures, and mean ADC values were calculated in a region of interest. These values were then correlated with the tumor grading offered by the histopathological examination, which was considered the gold standard. In this way, the patients were divided into three groups (G1, G2, and G3). The ADC values were then compared to the results offered by the biopsy to see if the DWI sequence and ADC map could replace this procedure. We also compared the mean ADC values to the myometrial invasion (50%) and lymphovascular space invasion.

RESULTS

We have divided the ADC values into three categories corresponding to three grades: >0.850 × 10-3 mm2/s (ADC1), 0.730-0.849 × 10-3 mm2/s (ADC2) and <0.730 × 10-3 mm2/s (ADC3). The diagnostic accuracy of the ADC value was 85.71% for ADC1, 75.76% for ADC2, and 91.66% for ADC3. In 77 cases out of 92, the category in which they were placed using the ADC value corresponded to the result offered by the histopathological exam with an accuracy of 83.69%. For only 56.52% of patients, the biopsy result included the grading system. For each grading category, the mean ADC value showed better results than the biopsy; for G1 patients, the mean ADC value had an accuracy of 85.71% compared to 66.66% in the biopsy, G2 had 75.76% compared to 68.42%, and G3 had 91.66 compared to 75%. For both deep myometrial invasion and lymphovascular space invasion, there is a close, inversely proportional correlation with the mean ADC value.

CONCLUSIONS

Mean endometrial tumor ADC on MR-DWI is inversely related to the histological grade, deep myometrial invasion and lymphovascular space invasion. Using this method, the patients could be better divided into risk categories for personalized treatment.

Clinical Utility of Diffusion-Weighted Imaging in Gynecological Imaging: Revisited

ABSTRACT

Diffusion-weighted imaging (DWI) is an increasingly valuable sequence in daily clinical practice, providing both functional and morphological information. The use of DWI can help quantify diffusion using the apparent diffusion coefficient, which reflects the physiological features of the tissue and tumor microcirculation. This knowledge is crucial for understanding and interpreting gynecological imaging. This article reviews the clinical utility of DWI for gynecological imaging, highlighting its ability to aid in the detection of endometrial and cervical cancers, as well as tumor extension and metastasis. In addition, DWI can easily detect the solid components of ovarian cancer (including dissemination), assist in the diagnosis of adnexal torsion, and potentially show bone marrow status. Apparent diffusion coefficient measurement is useful for differentiating between endometrial lesions, uterine leiomyomas, and sarcomas, and may provide important information for predicting the prognosis of gynecological cancers.

The role of diffusion magnetic resonance imaging in determining tumor aggressiveness during preoperative surgical planning in early-stage endometrial cancer

PURPOSE

The present study aimed to evaluate the relationship between tumor volume and apparent diffusion coefficient (ADC) in preoperative magnetic resonance imaging and deep myometrial invasion, tumor grade, and lymphovascular space invasion (LVSI) in patients with early-stage endometrial cancer.

METHODS

The study included 73 patients diagnosed with early-stage endometrial cancer based on histopathological examination between May 2014 and July 2019. Receiver operating characteristic (ROC) curve analysis was used to estimate the accuracy of ADC and tumor volume in predicting the LVSI, the depth of myometrial invasion (DMI), and the histopathological tumor grade in these patients.

RESULTS

The areas under the ROC curves (AUCs) of ADC and tumor volume in predicting LVI, DMI, and high tumor grade were significantly greater than those for superficial myometrial invasion and low-grade tumors. The ROC analysis revealed that higher tumor volume was significantly associated with the prediction of DMI and tumor grade (p = 0.002 and p = 0.015). The corresponding cut-off values of tumor volume were > 7.12 and > 9.38 mL. The sensitivity of ADC in predicting DMI was higher than its sensitivity in predicting LVSI and grade 1 tumors. Furthermore, tumor volume was significantly associated with the prediction of DMI and tumor grade.

CONCLUSION

In the absence of pathological pelvic lymph nodes in early-stage endometrial cancer, tumor volume in DWI sequences determines the active tumor load and tumor aggressiveness. Furthermore, a low ADC indicates deep myometrial invasion and helps differentiate stage IA and stage IB tumors.

Imaging of Endometrial Cancer

Endometrial cancer is the most common gynecologic cancer in the United States and Europe, with an increasing incidence rate in high-income countries. MR imaging is recommended for treatment planning because it provides critical information on the extent of myometrial and cervical invasion, extrauterine spread, and lymph node status, all of which are important in the selection of the most appropriate therapy. This article highlights the added value of imaging, focused on MR imaging, in the assessment of endometrial cancer and summarizes the role of MR imaging for endometrial cancer risk stratification and management.

Diagnostic value of the apparent diffusion coefficient in differentiating malignant from benign endometrial lesions

Introduction

Magnetic resonance imaging (MRI) with its innovative techniques, such as diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC), increases the diagnostic accuracy in distinguishing between malignant and benign lesions of the endometrium. The aim of the study was MRI differentiation between malignant and benign endometrial lesions and correlation with histopathological findings with a special emphasis on quantitative analysis. An additional aim was to correlate the ADC values and histological tumor grades.

Methods

The prospective study included 119 female patients with or without vaginal bleeding and pathological values of endometrial thickness, who underwent MRI examinations. According to MRI reports the patients were divided into 45 suspicious malignant and 74 suspicious benign endometrial lesions. The radiological diagnosis was compared to the histopathological evaluation, which confirmed 37 malignant lesions while the rest were benign.

Results

The mean ADC value for malignant lesions was 0.761 ± 0.13×10^-3 mm²/s and for benign lesions was 1.318 ± 0.20×10^-3 mm²/s. The ADC values for malignant lesions were expectedly lower than those of benign lesions (p<0.001). The ADC cut-off value was 1.007×10^-3 mm²/s with a sensitivity of 100%, specificity of 92.7%, a positive predictive value of 60.3%, and a negative predictive value of 100%. In comparison with the histopathological findings, the sensitivity of MRI was 100%, specificity 90.2%, positive predictive value was 82.2%, and negative predictive value was 100%. Observing the histological grades 1, 2, and 3 of endometrial carcinoma, no statistically significant differences of mean ADC values were found. The mean ADC values for histological tumor grades 1,2 and 3 were 0.803 ± 0.13×10^-3 mm²/s, 0.754 ± 0.12×10^-3 mm²/s and 0.728 ± 0.13×10^-3 mm²/s, respectively.

Conclusion

DWI and ADC values represent clinically useful tools for the differentiation between malignant and benign endometrial lesions with high sensitivity and good specificity, but the results failed to demonstrate their usefulness in differentiating histological grades of endometrial cancer.

Whole-lesion apparent diffusion coefficient (ADC) histogram as a quantitative biomarker to preoperatively differentiate stage IA endometrial carcinoma from benign endometrial lesions

BACKGROUND

To assess the value of whole-lesion apparent diffusion coefficient (ADC) histogram analysis in differentiating stage IA endometrial carcinoma (EC) from benign endometrial lesions (BELs) and characterizing histopathologic features of stage IA EC preoperatively.

METHODS

One hundred and six BEL and 126 stage IA EC patients were retrospectively enrolled. Eighteen volumetric histogram parameters were extracted from the ADC map of each lesion. The Mann-Whitney U or Student's t-test was used to compare the differences between the two groups. Models based on clinical parameters and histogram features were established using multivariate logistic regression. Receiver operating characteristic (ROC) analysis and calibration curves were used to assess the models.

RESULTS

Stage IA EC showed lower ADC_10th, ADC_90th, ADC_min, ADC_max, ADC_mean, ADC_median, interquartile range, mean absolute deviation, robust mean absolute deviation (rMAD), root mean squared, energy, total energy, entropy, variance, and higher skewness, kurtosis and uniformity than BELs (all p < 0.05). ADC_median yielded the highest area under the ROC curve (AUC) of 0.928 (95% confidence interval [CI] 0.895-0.960; cut-off value = 1.161 × 10^-3 mm²/s) for differentiating stage IA EC from BELs. Moreover, multivariate analysis demonstrated that ADC-score (ADC_10th + skewness + rMAD + total energy) was the only significant independent predictor (OR = 2.641, 95% CI 2.045-3.411; p < 0.001) for stage IA EC when considering clinical parameters. This ADC histogram model (ADC-score) achieved an AUC of 0.941 and a bias-corrected AUC of 0.937 after bootstrap resampling. The model performed well for both premenopausal (accuracy = 0.871) and postmenopausal (accuracy = 0.905) patients. Besides, ADC_min and ADC_10th were significantly lower in Grade 3 than in Grade 1/2 stage IA EC (p = 0.022 and 0.047). At the same time, no correlation was found between ADC histogram parameters and the expression of Ki-67 in stage IA EC (all p > 0.05).

CONCLUSIONS

Whole-lesion ADC histogram analysis could serve as an imaging biomarker for differentiating stage IA EC from BELs and assisting in tumor grading of stage IA EC, thus facilitating personalized clinical management for premenopausal and postmenopausal patients.

Multimodal MRI-Based Radiomics-Clinical Model for Preoperatively Differentiating Concurrent Endometrial Carcinoma From Atypical Endometrial Hyperplasia

Objectives

To develop and validate a radiomics model based on multimodal MRI combining clinical information for preoperative distinguishing concurrent endometrial carcinoma (CEC) from atypical endometrial hyperplasia (AEH).

Materials and Methods

A total of 122 patients (78 AEH and 44 CEC) who underwent preoperative MRI were enrolled in this retrospective study. Radiomics features were extracted based on T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) maps. After feature reduction by minimum redundancy maximum relevance and least absolute shrinkage and selection operator algorithm, single-modal and multimodal radiomics signatures, clinical model, and radiomics-clinical model were constructed using logistic regression. Receiver operating characteristic (ROC) analysis, calibration curves, and decision curve analysis were used to assess the models.

Results

The combined radiomics signature of T2WI, DWI, and ADC maps showed better discrimination ability than either alone. The radiomics-clinical model consisting of multimodal radiomics features, endometrial thickness >11mm, and nulliparity status achieved the highest area under the ROC curve (AUC) of 0.932 (95% confidential interval [CI]: 0.880-0.984), bootstrap corrected AUC of 0.922 in the training set, and AUC of 0.942 (95% CI: 0.852-1.000) in the validation set. Subgroup analysis further revealed that this model performed well for patients with preoperative endometrial biopsy consistent and inconsistent with postoperative pathologic data (consistent group, F1-score = 0.865; inconsistent group, F1-score = 0.900).

Conclusions

The radiomics model, which incorporates multimodal MRI and clinical information, might be used to preoperatively differentiate CEC from AEH, especially for patients with under- or over-estimated preoperative endometrial biopsy.

The efficacy of deep learning models in the diagnosis of endometrial cancer using MRI: a comparison with radiologists

Purpose

To compare the diagnostic performance of deep learning models using convolutional neural networks (CNN) with that of radiologists in diagnosing endometrial cancer and to verify suitable imaging conditions.

Methods

This retrospective study included patients with endometrial cancer or non-cancerous lesions who underwent MRI between 2015 and 2020. In Experiment 1, single and combined image sets of several sequences from 204 patients with cancer and 184 patients with non-cancerous lesions were used to train CNNs. Subsequently, testing was performed using 97 images from 51 patients with cancer and 46 patients with non-cancerous lesions. The test image sets were independently interpreted by three blinded radiologists. Experiment 2 investigated whether the addition of different types of images for training using the single image sets improved the diagnostic performance of CNNs.

Results

The AUC of the CNNs pertaining to the single and combined image sets were 0.88–0.95 and 0.87–0.93, respectively, indicating non-inferior diagnostic performance than the radiologists. The AUC of the CNNs trained with the addition of other types of single images to the single image sets was 0.88–0.95.

Conclusion

CNNs demonstrated high diagnostic performance for the diagnosis of endometrial cancer using MRI. Although there were no significant differences, adding other types of images improved the diagnostic performance for some single image sets.

Does diffusion weighted imaging have a prognostic value in differentiating gynecological diseases?

INTRODUCTION

Apparent diffusion coefficient (ADC) values are effective in the diagnosis of different gynecological lesions.

METHODS

A retrospective evaluation was made of 12 patients with uterine cervix carcinoma and 151 patients with uterine lesions, comprising endometrial cancer, endometrial polyps, carcinosarcoma, submucous myoma, adenomyosis, endometrial hyperplasia, gestational trophoblastic neoplasm (GTN), and leiomyomas. As a control group, 20 healthy volunteers with normal endometrium and normal cervix were also evaluated. In three series, one-shot, spin echo, echo planar, b = 1000 s/mm² value and diffusion-weighted imaging (DWI) were applied to all subjects and ADC values were obtained.

RESULTS

The mean ADC values of Group 1 (Endometrial carcinoma) were lower than those of all the other groups (P < 0.001) and the mean ADC value of group 6 (GTN) was higher than that all other groups (P < 0.001). A statistically significant difference was found between the groups in terms of the lesion-myometrium ADC ratios (P < 0.001).

CONCLUSION

There are few studies in literature related to ADC measurements in GTN. The ADC values of GTN were found to be significantly higher than the other uterine lesions. These results will aid in the design of future studies and might be used to guide management of patients with GTN.

IMPLICATIONS FOR PRACTICE

Diffusion-weighted MRI seems to be a promising imaging technique in differentiating different uterine lesions.

The utility of diffusion-weighted imaging and ADC values in the characterization of mumps orchitis and seminoma

BACKGROUND

Diffusion-weighted imaging (DWI) can quantitatively reflect the diffusion characteristics of tissues, providing a theoretical basis for qualitative diagnosis and quantitative analysis of a disease.

PURPOSE

To characterize testicular lesions that present as a hypointense signal on magnetic resonance imaging (MRI) T2-weighted images using DWI.

MATERIAL AND METHODS

Study participants were divided into three groups. Group A were healthy controls (n = 35), group B included patients with mumps orchitis (n = 20), and group C included patients with seminoma (n = 15). DWI sequences used b-values of 0, 1000, and 2000 s/mm². Apparent diffusion coefficient (ADC) values between 1000 and 2000 s/mm² were calculated by MRI postprocessing software. The Kruskal-Wallis test and receiver operating characteristic analysis were performed to evaluate how well ADC values distinguished between mumps orchitis and seminoma.

RESULTS

Normal testicular tissue showed a hyperintense signal on DWI and hypointensity on the ADC map: mean ADC value was 0.77 (0.69-0.85) ± 0.08 ×10^-3 mm²/s. Mumps orchitis and seminoma showed slight hyperintensity on DWI: mean ADC values were 0.85 (0.71-0.99) ± 0.15 ×10^-3 mm²/s and 0.43 (0.39-0.47) ± 0.04 × 10^-3 mm²/s, respectively. There were statistically significant differences in mean ADC values between normal testicular tissue and seminoma and between mumps orchitis and seminoma. The cutoff ADC value for differentiating seminoma from mumps orchitis was 0.54 × 10^-3 mm²/s. The sensitivity, specificity, and Youden Index for diagnosing seminoma were 99%, 31%, and 30%, respectively.

CONCLUSION

High b-value DWI has potential utility for differentiating mumps orchitis from seminoma in the clinical setting.

MRI-based radiomics model for distinguishing endometrial carcinoma from benign mimics: A multicenter study

PURPOSE

To develop and validate an MRI-based radiomics model for preoperatively distinguishing endometrial carcinoma (EC) with benign mimics in a multicenter setting.

METHODS

Preoperative MRI scans of EC patients were retrospectively reviewed and divided into training set (158 patients from device 1 in center A), test set #1 (78 patients from device 2 in center A) and test set #2 (109 patients from device 3 in center B). Two radiologists performed manual delineation of tumor segmentation on the map of apparent diffusion coefficient (ADC), diffusion-weighted imaging (DWI) and T2-weighted imaging (T2WI). The features were extracted and firstly selected using Chi-square test, followed by refining using binary least absolute shrinkage and selection operator (LASSO) regression. The support vector machine (SVM) was employed to build the radiomics model, which is tuned in the training set using 10-fold cross-validation, and then assessed on the test set. Performance of the model was determined by area under the receiver-operating characteristic curve (AUC), accuracy, sensitivity, specificity and F1-score.

RESULTS

Five most informative features are selected from the extracted 3142 features. The SVM with linear kernel was employed to build the radiomics model. The AUCs of the model were 0.989 (95% confidence interval [CI]: 0.968-0.997) for the training set, 0.999 (95% CI: 0.991-1.000) for test set #1, 0.961 (95% CI: 0.902-0.983) for test set #2. Accuracies of the model were 0.937 for the training set (precision: 0.919, recall: 0.963, F1-score: 0.940), 0.974 for test set #1 (precision: 0.949, recall: 1.000, F1-score: 0.974) and 0.908 for test set #2 (precision: 0.899, recall: 0.954, F1-score: 0.925). These results confirmed the efficacy of this model in predicting EC in different centers.

CONCLUSION

The MRI-based radiomics model showed promising potential for distinguishing EC with benign mimics and might be useful for surgical management of EC.

MRI of the endometrium - from normal appearances to rare pathology

MRI was recently included as a standard pre-operative diagnostic tool for patients with endometrial cancer. MR findings allow a better risk assessment and ultimately guides the surgical planning. Therefore, it is vital that the radiological interpretation is as accurate as possible. This requires essential knowledge regarding the appropriate MRI protocol, as well as different appearances of the endometrium, ranging from normal peri- and post-menopausal changes, benign findings (e.g. endometrial hyperplasia, polyp, changes due to exogenous hormones) to common and rare endometrium-related malignancies. Furthermore, this review will emphasize the role of MRI in staging endometrial cancer patients and highlight pitfalls that could result in the underestimation or overestimation of the disease extent.

Benign Uterine Disease: The Added Role of Imaging

Benign uterine diseases are very common gynecologic conditions that affect women mostly in reproductive age. Ultrasound examination is the first-line imaging technique, but MRI is more accurate for diagnosis, characterization, and patient management. In this review, we especially highlight the added value of MRI in the diagnosis of benign uterine disease, discuss their imaging characteristics, and describe the therapeutic options and the added value of MRI in the treatment planning.

Diagnostic performance of apparent diffusion coefficient (ADC) for differentiating endometrial carcinoma from benign lesions: a systematic review and meta-analysis

To determine the diagnostic performance of mean ADC values in the characterization of endometrial carcinoma (EC) from benign lesions by systematic review of the literature and performing meta-analysis. A systematic search of major electronic bibliographic databases was performed to find studies that used ADC values for differentiating EC from benign lesions. Two reviewers independently screened the titles and abstracts of the search results and then by reading the full texts selected the pertinent studies for final analyses. A bivariate random-effects model with pooled sensitivity and specificity values with 95% CI (confidence interval) was used. Summary receiver operating characteristic (SROC) curve and area under curve (AUC) were created. Between-study heterogeneity was measured using I squared (I2) index. Eleven studies including 269 ECs and 208 benign lesions were analyzed. Pooled average (95% CI) ADC in EC and benign lesions groups were, respectively, 0.82 (0.77-0.87) × 10-3 mm2/s and 1.41 (1.29-1.52) × 10-3 mm2/s. The combined (95% CI) sensitivity and specificity of mean ADC values for differentiating EC from benign lesions were 93% (87-96%; I2 = 41.19%) and 94% (88-97%; I2 = 46.91%), respectively. The AUC (95% CI) of the SROC curve was 98% (96-99%). ADC values had good diagnostic accuracy for differentiating EC from benign lesions. In order to recommend ADC measurement for detecting endometrial lesions in routine clinical practice, more primary studies, especially trials and comparative studies including hysteroscopically-guided biopsy method, with larger sample sizes are still required.

Normalized apparent diffusion coefficient: a novel paradigm for characterization of endometrial and subendometrial lesions

OBJECTIVES

To assess the role of normalized apparent diffusion coefficient (ADC) in characterization of endometrial and subendometrial masses, measured as a ratio of the mean ADC of the pathology to mean ADC of two different internal controls, normal myometrium and gluteus maximus muscle, referred to as nADC_m and nADC_g respectively.

METHODS

55 females with pathologically proven endometrial and subendometrial lesions, including 27 cases of endometrial carcinoma, and 28 cases of benign masses were enrolled in this prospective study and assessed with single-shot echoplanar diffusion-weighted imaging. The normalized and absolute ADC of the lesions, measured by two radiologists, were compared in different pathologies and receiver operating characteristics (ROC) performed to distinguish benign and malignant endometrial masses. In the endometrial carcinoma group, the ADC values were further compared with tumor grade and subtype.

RESULTS

There was good interobserver agreement (>0.800) for both internal controls, however it was higher for myometrium [intraclass correlation coefficient-0.92; confidence interval (0.86-0.95)] than gluteus maximus muscle [ICC-0.84; CI (0.72-0.90)]. There were statistically significant differences in absolute ADC (p-0.02), nADC_m (p-0.02) and nADC_g (p < 0.0001) of benign and malignant endometrial masses.

CONCLUSION

Normalized ADC is useful to distinguish benign and malignant masses with comparable accuracy as absolute ADC.

ADVANCES IN KNOWLEDGE

Normalized ADC represents an easily measurable quantitative parameter which limits the influence of endogenous and exogenous factors that affect its reproducibility.

Role of Diffusion-Weighted Magnetic Resonance Imaging in the Diagnosis of Bladder Pain Syndrome/Interstitial Cystitis

Some recent studies evaluated the introduction of diffusion-weighted magnetic resonance imaging (DW-MRI) in the diagnosis of bladder pain syndrome/interstitial cystitis (BPS/IC).

OBJECTIVE

To evaluate whether DW-MRI can contribute to noninvasive diagnosis of BPS/IC. The agreement between two raters (2 radiologists involved in the study) was also evaluated, the relevance of the "operator-dependent" factor defined.

PATIENTS AND METHODS

Twenty-two female patients with a diagnosis of BPS-IC were recruited and performed DW-MRI. The same investigation was also performed in 20 patients with pelvic gynecological diseases and no BPS-IC.

RESULTS

A significant difference was found between BPS-IC and no-BPS-IC since 17 out of 22 subjects of the first group were positive, compared to 3 out of 20 no-IC subjects, with a P value of .001 to highlight the statistical significance. The sensitivity of the exam was 77%, while the specificity was 85%. There was good agreement between the 2 raters in the evaluation of MRI results.

CONCLUSION

DW-MRI helps to obtain a noninvasive diagnosis of BPS/IC, by providing useful information on the choice of which patients may be more appropriately submitted to cystoscopy and bladder biopsy.

The usefulness of diffusion-weighted MRI in the differentiation between focal uterine endometrial soft tissue lesions

Background

Several endometrial conditions may be challenging for radiologists due to the overlap of imaging features and variable endometrial pathologies. MRI with DWI is the most commonly used imaging technique for the diagnosis and characterization of endometrial focal lesions.

Results

The 50 studied lesions were classified according to their histopathological results into the benign group (28 lesions, 56%) and the malignant group (22 lesions, 44%). Conventional MRI could correctly diagnose 39 of the 50 lesions (22/28 benign and 17/22 malignant lesions), achieving a sensitivity of 77.27%, specificity of 78.56%, accuracy of 78%, predictive positive value (PPV) of 73.91%, and negative positive value (NPV) of 81.48%. By combining DWI and apparent diffusion coefficient (ADC) value mapping at a high b value (b = 1000) in MRI, we could correctly diagnose 47 of the 50 lesions (26/28 benign and 21/22 malignant lesions), with increased sensitivity (95.45%), specificity (92.86%), accuracy (94%), PPV (91.3%), and NPV (96%).

Conclusion

Combining DWI with ADC mapping at a high b value in pelvic MRI examination is valuable in differentiating endometrial focal lesions with increased diagnostic sensitivity, specificity, and accuracy.

Aim of the work

This study aimed to evaluate the role of DWI in the diagnosis and differential diagnosis of benign and malignant focal endometrial masses.

The diagnostic precision of apparent diffusion coefficient (ADC) in grading of malignant endometrial lesions compared with histopathological findings

OBJECTIVE

The present study aimed to extract apparent diffusion coefficient (ADC) values from the diffusion-weighted imaging (DWI) sequence of endometrial lesions and compare them with tissue specimen results in order to determine the precision of ADC values in grading of malignant endometrial lesions.

METHODS

The present prospective study was conducted on 22 patients complaining of abnormal vaginal bleeding or evidence for endometrial thickening or masses detected using the ultrasound. Sampling was performed for pathological examination. MRI T2W+DWI+T1W+Post Contrast T1W were performed for patients. The statistical analysis was performed in SPSS 20 and MedCalc.

RESULTS

In this study, although the mean ADC value was lower in patients with endometrial cancer than those with benign endometrial lesions, the difference was not significant (0.86 ± 0.2 mm²/sec versus 1.33 ± 0.53 mm²/sec; P = 0.13). Using the cutoff point of 0.53, the sensitivity and specificity of ADC value for differentiating benign and malignant lesions, respectively, equaled 90.91 and 9.09, with an equal positive and negative predictive value of 50%. In patients with endometrioid adenocarcinoma, mean ADC value was 0.93 ± 0.15 in FIGO Grade I, and 0.76 ± 0.165 in FIGO Grade II. Based on the statistical test, no significant difference existed between the two groups in terms of ADC values.

CONCLUSION

Results indicate that the use of a DWI sequence (ADC values) can prevent invasive measures in the diagnosis of benign endometrial lesions and the identification of malignant lesions with a high precision in many patients having accompanying diseases or other cases for which invasive measures cannot be used. Also, there is no significant difference in the mean ADC values between G1 and G2 of endometrioid carcinoma.

The ability of ADC measurements in the assessment of patients with stage I endometrial carcinoma based on three risk categories

BACKGROUND

Better selection of patients with intermediate and high-risk stage I endometrial carcinoma (EC) for lymphadenectomy has an important effect on the prognosis.

PURPOSE

To investigate the role of apparent diffusion coefficient (ADC) measurements in the assessment of stage I EC patients based on three risk categories.

MATERIAL AND METHODS

We retrospectively studied 80 patients with EC and 28 cervical cancer patients with normal endometrium. 1.5-T conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) (b = 0, 1000 s/mm²) were performed, and ADC values were calculated. Sixty-eight stage I EC patients were divided into three groups: low-risk EC (group 1); intermediate-risk EC (group 2); and high-risk EC (group 3). The remaining 12 EC patients were in stages II and III. Intraclass coefficient, Mann-Whitney U test, Kruskal-Wallis test, and receiver operating characteristics were used for statistical analysis.

RESULTS

The mean ADC values ( × 10^-3 mm² /s) were 0.851 ± 0.131, 0.734 ± 0.108, and 0.710 ± 0.108 for groups 1, 2 and 3, respectively. Significant statistical differences were achieved for the three groups ( P = 0.0005). The mean ADC values of group 1 were significantly lower than those in group 2 + 3 (0.725 ± 0.106; P = 0.0001). For the prediction of groups 2 + 3, the area under the curve of 0.786 and the cut-off value of ≤ 0.742 were identified, with a sensitivity, specificity, and accuracy of 66.67%, 84.09%, and 73.53%, respectively.

CONCLUSION

ADC measurements may have the potential to select intermediate-risk and high-risk stage I EC patients for lymphadenectomy.

Endometrial cancer: an overview of novelties in treatment and related imaging keypoints for local staging

Endometrial cancer is the most common gynaecologic malignancy in developed countries and its incidence is increasing. First-level treatment, if no contraindicated, is based on surgery. Pre-operative imaging is needed for evaluation of local extent and detection of distant metastases in order to guide treatment planning. Radiological evaluation, based on transvaginal ultrasound, MR and CT, can make the difference in disease management, paying special attention to assessment of entity of myometrial invasion, cervical stromal extension, and assessment of lymph nodal involvement and distant metastases.

The utility of measuring the apparent diffusion coefficient for peritumoral zone in assessing infiltration depth of endometrial cancer

BACKGROUND

The invasion depth of endometrial cancer is one of the most important prognosis factors. The aim of the current study was to investigate the diagnostic value of the apparent diffusion coefficient (ADC) of the peritumoral zone for assessing the infiltration depth of endometrial cancer.

METHODS

An institutional review board approved this prospective study, and all study participants provided informed consent. A total of 58 patients (mean age 54 ± 8.3 years, range 34-69 years) with endometrial cancer were prospectively enrolled. Two radiologists assessed all preoperative magnetic resonance images with T1, T2, and diffusion-weighted imaging, and determined the location of the deepest invasion of the tumor. The peritumoral zone was defined as a 5-mm-thick zone surrounding and adjacent to the cancerous endometrium. The mean ADC (ADCm) values of the tumor and the peritumoral zone were measured. Sensitivity, specificity, positive and negative predictive values, and the area under the receiver operating characteristic curve (Az) were calculated for visual inspection, and an ADC cutoff value for the peri-endometrial zone was determined for predicting the myometrial invasion depth.

RESULTS

The ADCm values of tumors and peritumoral zones were 0.83 × 10- 3 mm2/sec and 1.06 × 10- 3 mm2/sec, respectively. There was no significant difference between the ADCm values of the tumors in the superficial and deep myometrial invasion groups (P > 0.05). However, the ADCm value at the peritumoral zone in the deep myometrial invasion group (1.23 × 10- 3 mm2/sec) significantly differed from that in the superficial myometrial invasion group (0.99 × 10- 3 mm2/sec) (p = 0.005). In assessments of deep myometrial invasion, the sensitivity, specificity, negative predictive value, and positive predictive value were 0.58, 0.93, 0.84, and 0.77, respectively, for the ADCm cutoff value of the peritumoral zone, and 0.71, 0.80, 0.87, and 0.60. respectively, for visual inspection. The accuracy of myometrial invasion depth assessment using the ADCm cutoff value and visual inspection were 83 and 78%, respectively. The Az for both was 0.76.

CONCLUSION

ADCm at the peritumoral zone can predict deep myometrial invasion of endometrial cancer. This value can therefore enhance confidence in preoperative endometrial cancer evaluation, and when tailoring surgical approaches.

Evaluation and validation of the diagnostic value of the apparent diffusion coefficient for differentiating early-stage endometrial carcinomas from benign mimickers at 3T MRI

Previous researchers obtained various apparent diffusion coefficient (ADC) cutoff values to differentiate endometrial carcinoma from benign mimickers with 1.5T magnetic resonance imaging (MRI). Few studies have used 3T MRI or validated the effectiveness of these cutoff ADC values prospectively. This study was designed in two stages to obtain a cutoff ADC value at 3T MRI and to validate prospectively the role of the ADC value. First, we conducted a retrospective study of 60 patients to evaluate the diagnostic value of ADC by obtain a theoretical cutoff ADC value for differentiating between benign and malignant endometrial lesions. Student's t test revealed that ADC values for stage I endometrial carcinomas were significantly lower than those for benign lesions. The area under the curve value of the receiver operating characteristic curve was 0.993, and the cutoff ADC value was 0.98 × 10-3 mm2/s. The sensitivity, specificity, and overall accuracy of diagnosing stage I endometrial carcinoma were 100%, 97.1%, and 98.3%, respectively. Second, we conducted a prospective study of 26 patients to validate the use of the cutoff ADC value obtained in the study's first stage. The sensitivity, specificity, and overall accuracy for differentiating malignant from benign endometrial lesions based on the cutoff ADC value obtained earlier were as follows: radiologist 1 attained 86.67%, 100.0%, and 92.31%, respectively; radiologist 2 attained 86.67%, 91.0%, and 88.5%, respectively. Our results suggest that ADC values could be a potential biomarker for use as a quantitative and qualitative tool for differentiating between early-stage endometrial carcinomas and benign mimickers.

A Network Meta-Analysis on the Diagnostic Value of Different Imaging Methods for Lymph Node Metastases in Patients With Cervical Cancer

PURPOSE

We performed this network meta-analysis to compare the diagnostic value of 4 imaging methods (magnetic resonance imaging, positron emission tomography, computed tomography, and diffusion-weighted imaging) for diagnosing lymph node metastases in cervical cancer.

METHOD

Diagnostic tests regarding different imaging methods to diagnose lymph node metastases in cervical cancer were retrieved from the Cochrane Library, PubMed, and Embase electronic databases from inception to December 2016. Direct and indirect evidence was performed to calculate the odds ratio and to draw the surface under the cumulative ranking curves of the 4 imaging methods for diagnosing lymph node metastases in cervical cancer.

RESULTS

Sixteen eligible diagnostic tests were included in this network meta-analysis. The results of network meta-analysis demonstrate that in comparison with the diffusion-weighted imaging, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of positron emission tomography were relatively higher. Additionally, the results further indicate that compared with other diagnosis method, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of positron emission tomography had a higher trend. The surface under the cumulative ranking curve results indicated that in terms of positive likelihood ratio and diagnostic odds ratio, positron emission tomography had a relatively higher diagnostic value for lymph node metastases in patients with cervical cancer.

CONCLUSION

Our findings indicate that positron emission tomography might have a relatively higher diagnostic value for lymph node metastases in patients with cervical cancer.

Fertility-sparing for young patients with gynecologic cancer: How MRI can guide patient selection prior to conservative management

Historically, cancer treatment has emphasized measures for the "cure" regardless of the long-term consequences. Advances in cancer detection and treatment have resulted in improved outcomes bringing to the fore various quality of life considerations including future fertility. For many young cancer patients, fertility preservation is now an integral component of clinical decision-making and treatment design. Optimal fertility-sparing options for young patients with gynecologic cancer are influenced by patient age, primary cancer, treatment regimens, and patient preferences. Possible approaches include embryo or oocyte cryopreservation, ovarian transposition, conservative surgery, and conservative medical treatment to delay radical surgery. These may be used alone or in combination to maximize fertility preservation. Awareness of the various fertility-sparing options, eligibility criteria, and the central role of magnetic resonance imaging in the proper selection of patients will enable radiologists to produce complete clinically relevant imaging reports and serve as effective consultants to referring clinicians. Knowledge of the potential imaging pitfalls is essential to avoid misinterpretation and guide appropriate management.

Diffusion-weighted imaging in gynaecological malignancy

Diffusion weighted imaging (DWI) has become an essential part of the gynaecological magnetic resonance imaging (MRI) protocol. DWI is used as an adjunct to conventional MRI sequences and has been shown to improve reporting accuracy in the imaging of gynaecological malignancy. In this review, we discuss the role of DWI in the diagnosis, staging, and assessment of treatment response of endometrial, cervical, and ovarian cancer. We also review the role of DWI in the assessment of the sonographically indeterminate ovarian lesion. Further, we highlight potential pitfalls that can beset the accurate interpretation of DWI in patients with gynaecological malignancy.

Role of diffusion-weighted MRI in the differential diagnosis of endometrioid and non-endometrioid cancer of the uterus

Background Many publications have examined the relationship between apparent diffusion coefficient (ADC) values and tumor grade in endometrial cancer. Nevertheless, none were designed to evaluate according to the histopathological type of endometrioid and non-endometrioid tumors. Purpose To evaluate the role of diffusion-weighted imaging (DWI) in the differential diagnosis of endometrioid and non-endometrioid cancer of the uterus, by comparing them with contrast-enhanced magnetic resonance imaging (MRI) findings. Material and Methods Institutional review board approval and informed consent were obtained. The MRI findings of 63 patients with endometrial cancer were retrospectively evaluated and divided into four groups: Grades I, II, and III endometrioid tumors, and non-endometrioid tumors. ADC values, DWI quotients ( b = 1000 s/mm²), and post-contrast signal intensities between lesions and the myometrium (b1000q-Cq values) were evaluated. The one-way-ANOVA, student's t-test, Kruskal-Wallis test, and receiver operating characteristic (ROC) analysis were used for statistical evaluation. Results Mean ADC values were 0.86 ± 0.14 in Grade I, 0.80 ± 0.7 in Grade II, 0.71 ± 0.14 in Grade III for endometrioid tumors, and 0.70 ± 0.12 in non-endometrioid tumors. There was a significant difference in ADC values between Grade I and Grade III ( P = 0.006), and non-endometrioid tumors ( P = 0.003). The difference was also significant between Grades I + II and Grade III ( P = 0.009), and non-endometrioid tumors ( P = 0.004). Besides, there was a significant difference between endometrioid and non-endometrioid tumors ( P = 0.022). However, when considering b1000q (F = 0.640, P = 0.593) and Cq (χ²= 6.233; P = 0.101), no significant difference was detected among the groups. Conclusion The difference in ADC values between the endometrioid and non-endometrioid tumors was statistically significant. However, the difference in DWI and contrast-enhancement findings were not statistically significant. Furthermore, the mean ADC values had an inverse relationship with tumor grade in the endometrioid cancer group.

Current strategies in the diagnosis of endometrial cancer

PURPOSE

Endometrial cancer is the most common gynecological malignancy in developed countries. There are no uniform recommendations for endometrial cancer screening in the general population. Therefore, it is of paramount importance that the primary physician profoundly understands, and is familiar with the methods for prevention and early detection of endometrial cancer. The aim of this review is to provide the primary physician with a toolbox to reach these goals.

METHODS

We performed a systemic review to summarize the current strategies to diagnose and prevent endometrial cancer. Many published articles from the last years were identified and included.

RESULTS

A systematic review that summarizes the important subjects in the diagnosis and prevention of endometrial cancer.

CONCLUSION

Maintaining a high index of suspicion and obtaining endometrial biopsies from all suspected patients is the key for achieving a timely diagnosis.

Functional MR imaging in gynecologic malignancies: current status and future perspectives

Using functional MR imaging techniques, we can approach the functional assessment of gynecologic malignancies. Among them, diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MR imaging (DCE-MRI) are two important techniques. This article provides an overview of functional MR imaging techniques, focusing DWI and DCE-MRI on clinical application in gynecologic malignancies. Functional MR imaging techniques play an important role in detection, characterization, staging, treatment response, and outcome prediction, as well as providing conventional morphologic imaging. Familiarity with the characteristics and imaging features of functional MR imaging in gynecologic malignancies will facilitate prompt and accurate diagnosis and treatment.

Endometrial cancer: correlation of apparent diffusion coefficient (ADC) with tumor cellularity and tumor grade

BACKGROUND

Diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) are widely used for detecting uterine endometrial cancer. The relationships between ADC values and pathological features of endometrial cancer have not yet been established.

PURPOSE

To investigate whether ADC values of endometrial cancer vary according to histologic tumor cellularity and tumor grade.

MATERIAL AND METHODS

We retrospectively reviewed 30 pathologically confirmed endometrial cancers. All patients underwent conventional non-enhanced magnetic resonance imaging (MRI) and DWI procedures, and ADC values were calculated. Tumor cellularity was evaluated by counting cancer cells in three high-power ( × 400) fields. The correlation between ADC values and tumor cellularity was assessed using Pearson's correlation coefficient test for statistical analysis.

RESULTS

The mean ± standard deviation (SD) ADC value ( ×10(-3) mm(2)/s) of endometrial cancer was 0.85 ± 0.22 (range, 0.55-1.71). The mean ± SD tumor cellularity was 528.36 ± 16.89 (range, 298.0-763.6). ADC values were significantly inversely correlated with tumor cellularity. No significant relationship was observed between ADC values and tumor grade (mean ADC values: G1, 0.88 ± 0.265 × 10(-3) mm(2)/s; G2, 0.80 ± 0.178 × 10(-3) mm(2)/s; G3, 0.81 ± 0.117 × 10(-3) mm(2)/s).

CONCLUSION

There is a significant inverse relationship between ADC values and tumor cellularity in endometrial cancer. No significant differences in average ADC value were observed between G1, G2, and G3 tumors. However, the lower the tumor grade, the wider the SD.

Diffusion-Weighted Mri of Postmenopausal Women with Vaginal Bleeding and Endometrial Thickening: Differentiation of Benign and Malignant Lesions

Purpose:

To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DWI) with apparent diffusion coefficient (ADC) values in differentiating endometrial cancer from benign endometrial lesions in postmenopausal patients with vaginal bleeding and endometrial thickening and to predict the depth of myometrial invasion in endometrial cancer.

Materials and Methods:

Postmenopausal patients with vaginal bleeding and endometrial thickening were enrolled in this prospective study. T2-weighted, pre- and postcontrast T1-weighted and diffusion-weighted images were obtained. The ADC values of all the patients with endometrial pathologies were recorded. The staging accuracies of DWI and postcontrast T1-weighted images in the assessment of myometrial invasion were evaluated in histopathologically proven endometrial cancer patients.

Results:

Fifty-two patients (mean age: 57 ± 10, range: 41–79) were enrolled in the study. Thirty-eight of the lesions were benign (27 as hyperplasia and endometritis; 11 as polyps). Fourteen of the 52 endometrial lesions were pathologically proven as cancers and underwent hysterectomy, and all the specimens were reported as endometrioid adenocarcinomas. The mean ADC value (10^–3 mm²/second) of cancer (0.88 ± 0.10) was significantly lower than that of benign lesions (1.78 ± 0.27, p = 0,001). There was no significant difference between ADC values of endometrial tissue in patients with FIGO stage 1A (0.87 ± 0.11, n = 9) and FIGO stage 1B (0.91 ± 0.07, n = 5). The staging accuracy was 92.9 per cent (13/14) for DWI and 85.7 per cent (12/14) for postcontrast T1-weighted images.

Conclusion:

ADC values allow benign endometrial lesions to be differentiated from endometrial cancer in postmenopausal patients but do not correlate with the depth of myometrial invasion and histological tumor grading.

Comparison of retrospective PET and MRI-DWI (PET/MRI-DWI) image fusion with PET/CT and MRI-DWI in detection of cervical and endometrial cancer lymph node metastases

OBJECTIVES

The aim of this study was to compare the accuracy of retrospective image fusion of PET/MRI-DWI with that of PET/CT and MRI-DWI alone in detecting metastatic lymph nodes in patients with cervical and endometrial carcinoma.

MATERIALS AND METHODS

Twenty-seven patients with endometrial (n = 14) and cervical (n = 13) cancer who had undergone preoperative MRI-DWI and PET/CT for staging were retrospectively evaluated. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PET/CT, MRI-DWI, and PET/MRI-DWI image fusion were calculated on a per-patient basis and on a per-node basis. Histopathological and follow-up imaging results were used as the gold standard.

RESULTS

On a per-patient basis PET/MRI-DWI had the same sensitivity (87.5 %), specificity (84.2 %), diagnostic accuracy (85.1 %), PPV (70 %), and NPV (94.1 %) as PET-CT, but on a per-node basis PET/MRI-DWI showed better sensitivity (89 vs 70.2 %), specificity (91.6 vs 90.5 %), diagnostic accuracy (91.2 vs 87 %), PPV (68.7 vs 60.4 %), and NPV (97.6 vs 93.6 %) than PET-CT. Comparison of the areas under the ROC curves for the detection of metastatic lymph nodes demonstrated a non-significant difference (p = 0.055) between PET/CT and fused PET/MRI-DWI.

CONCLUSION

PET/MRI-DWI may be a valuable technique for N-staging patients with endometrial and cervical cancer, but more studies are needed to investigate its potential clinical utility.

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.

Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients, in-vitro and in-vivo reproducibility

There is considerable disparity in the published apparent diffusion coefficient (ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to determine its variation, which could potentially be used as an indicator in determining tumour aggressiveness or assessing tumour response. In this manuscript, a review of selected articles published to date in healthy extra-cranial body diffusion-weighted magnetic resonance imaging is presented, detailing reported ADC values and discussing their variation across different studies. In total 115 studies were selected including 28 for liver parenchyma, 15 for kidney (renal parenchyma), 14 for spleen, 13 for pancreatic body, 6 for gallbladder, 13 for prostate, 13 for uterus (endometrium, myometrium, cervix) and 13 for fibroglandular breast tissue. Median ADC values in selected studies were found to be 1.28 × 10(-3) mm(2)/s in liver, 1.94 × 10(-3) mm(2)/s in kidney, 1.60 × 10(-3) mm(2)/s in pancreatic body, 0.85 × 10(-3) mm(2)/s in spleen, 2.73 × 10(-3) mm(2)/s in gallbladder, 1.64 × 10(-3) mm(2)/s and 1.31 × 10(-3) mm(2)/s in prostate peripheral zone and central gland respectively (combined median value of 1.54×10(-3) mm(2)/s), 1.44 × 10(-3) mm(2)/s in endometrium, 1.53 × 10(-3) mm(2)/s in myometrium, 1.71 × 10(-3) mm(2)/s in cervix and 1.92 × 10(-3) mm(2)/s in breast. In addition, six phantom studies and thirteen in vivo studies were summarized to compare repeatability and reproducibility of the measured ADC. All selected phantom studies demonstrated lower intra-scanner and inter-scanner variation compared to in vivo studies. Based on the findings of this manuscript, it is recommended that protocols need to be optimised for the body part studied and that system-induced variability must be established using a standardized phantom in any clinical study. Reproducibility of the measured ADC must also be assessed in a volunteer population, as variations are far more significant in vivo compared with phantom studies.