3-T diffusion tensor imaging (DTI) of normal uterus in young and middle-aged females during the menstrual cycle: evaluation of the cyclic changes of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values

Simulation of Uterus Active Contraction and Fetus Delivery in ls-dyna

Vaginal childbirth is the final phase of pregnancy when one or more fetuses pass through the birth canal from the uterus, and it is a biomechanical process. The uterine active contraction, causing the pushing force on the fetus, plays a vital role in regulating the fetus delivery process. In this project, the active contraction behaviors of muscle tissue were first modeled and investigated. After that, a finite element method (FEM) model to simulate the uterine cyclic active contraction and delivery of a fetus was developed in ls-dyna. The active contraction was driven through contractile fibers modeled as one-dimensional truss elements, with the Hill material model governing their response. Fibers were assembled in the longitudinal, circumferential, and normal (transverse) directions to correspond to tissue microstructure, and they were divided into seven regions to represent the strong anisotropy of the fiber distribution and activity within the uterus. The passive portion of the uterine tissue was modeled with a Neo Hookean hyperelastic material model. Three active contraction cycles were modeled. The cyclic uterine active contraction behaviors were analyzed. Finally, the fetus delivery through the uterus was simulated. The model of the uterine active contraction presented in this paper modeled the contractile fibers in three-dimensions, considered the anisotropy of the fiber distribution, provided the uterine cyclic active contraction and propagation of the contraction waves, performed a large deformation, and caused the pushing effect on the fetus. This model will be combined with a model of pelvic structures so that a complete system simulating the second stage of the delivery process of a fetus can be established.

Diagnostic value of diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) in differentiation between normal and abnormally thickened endometrium: prospective study

Background

Diffusion tensor imaging (DTI) can be beneficial to differentiate between endometrium and other uterine layers. It is believed that it can be used to differentiate between normal and abnormally thickened endometrium. The purpose of this study was to find out the diagnostic value of DTI as an extension of DWI in characterization of abnormally thickened endometrium and differentiate it from normal.

Results

This study included 68 females, results of 3 of them were excluded (unable to complete the study), so the final number was 65 females subdivided into 2 groups; (A) control: 24 (13 premenopausal and 11 asymptomatic postmenopausal), (B) pathological thickened endometrium: 41 (11 premenopausal and 30 postmenopausal): benign (21 patients) and malignant (20 patients). The collected data was correlated to the histopathological results (as the gold standard) in cases of endometrial pathologies. The mean DW-ADC values for normal, benign, and malignant patients were 1.43 ± 0.13, 1.56 ± 0.17, and 0.86 ± 0.16 respectively and with significant statistical difference between normal and benign endometrial lesions (P value = 0.006), and between normal and malignant endometrial lesions, and between benign and malignant endometrial lesions (P value ˂ 0.001).

The DTI-FA mean values for normal, benign, and malignant patients were 0.349 ± 0.08, 0.29 ± 0.09, and 0.299 ± 0.08 respectively and with significant statistical difference between normal and benign endometrial lesions (P value = 0.02), but there is no significant statistical difference regarding DTI-FA values between normal and malignant endometrial lesions or between benign and malignant endometrial lesions (P value ˃ 0.05). Also, there is a significant statistical difference regarding DTI-MD mean values between normal (1.59 ± 0.06) and benign (1.37 ± 0.09), normal and malignant (0.71 ± 0.25), and between benign and malignant endometrial lesions (P value ˂ 0.001). The DT-MD had a higher sensitivity, specificity, and accuracy than both DW-ADC and DT-FA in differentiating normal, benign, and malignant endometrial pathologies.

Conclusion

DTI (added to DWI) is a valuable non-invasive tool that can increase the accuracy in differentiating normal, benign, and malignant endometrial conditions, helping early management, and decrease the possibility of misdiagnosis.

Diagnostic Value of Combined Intravoxel Incoherent Motion Diffusion-Weighted Magnetic Resonance Imaging with Diffusion Tensor Imaging in Predicting Parametrial Infiltration in Cervical Cancer

Objective

This study sought to determine the diagnostic value of combined intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) in predicting parametrial infiltration (PMI) in patients with cervical cancer.

Materials and Methods

We enrolled 65 patients with cervical cancer confirmed by radical hysterectomy (25 PMI-negative and 40 PMI-positive) who underwent IVIM and DTI pretreatment. The parameters of IVIM (ADC, D, D  ^∗ , and f) and DTI (average diffusion coefficient (DCavg) and fractional anisotropy (FA)) were recorded by two observers. All parameter differences were tested, and the receiver operating characteristic (ROC) curves were generated to estimate the diagnostic performance of significant metrics and their combinations.

Results

Compared to the PMI-negative group, the PMI-positive group had significantly lower D (0.632 ± 0.017 vs. 0.773 ± 0.024, p < 0.001) and lower FA (0.073 ± 0.002 vs. 0.085 ± 0.003, p=0.003). The area under the ROC curve (AUC) of D and FA was 0.801 and 0.726, respectively, and the combination of D and FA improved the AUC to 0.931, with a sensitivity and specificity of 80.0% and 97.5%, respectively.

Conclusion

D and FA values could be used to help diagnose PMI in patients with cervical cancer. The combination of IVIM and DTI was more valuable than either option alone.

Objective measures of adenomyosis on MRI and their diagnostic accuracy-a systematic review & meta-analysis

INTRODUCTION

Magnetic resonance imaging (MRI) diagnosis of adenomyosis is considered the most accurate non-invasive technique, but remains subjective, with no consensus on which diagnostic parameters are most accurate. We aimed to systematically review the literature on how adenomyosis can be objectively quantified on MRI in a scoping manner, to review the diagnostic performance of these characteristics compared with histopathological diagnosis, and to summarize correlations between measures of adenomyosis on MRI and clinical outcomes.

MATERIAL AND METHODS

We searched databases Pubmed, Embase, and Cochrane for relevant literature up to April 2020 according to PRISMA guidelines. We included studies that objectively assessed adenomyosis on MRI, and separately assessed studies investigating the diagnostic performance of MRI vs histopathology for inclusion in a meta-analysis. The QUADAS-2 tool was used for risk of bias, with many studies showing an unclear or high risk of bias.

RESULTS

Eighty studies were included, of which 14 assessed the diagnostic performance of individual MRI parameters, with four included in the meta-analysis of diagnostic accuracy. Common MRI parameters were: junctional zone (JZ) characteristics, such as maximum JZ thickness-pooled sensitivity 71.6% (95% CI 46.0%-88.2%), specificity 85.5% (52.3%-97.0%); JZ differential-pooled sensitivity 58.9% (95% CI 44.3%-72.1%), specificity 83.2% (95% CI 71.3%-90.8%); and JZ to myometrial ratio-pooled sensitivity 63.3% (95% CI 51.9%-73.4%), specificity 79.4% (95% CI 42.0%-95.4%); adenomyosis lesion size, uterine morphology (pooled sensitivity 42.9% (95% CI 15.9%-74.9%), specificity 87.7%, (95% CI 37.9-98.8) and changes in signal intensity-eg, presence of myometrium cysts; pooled 59.6% (95% CI 41.6%-75.4%) and specificity of 96.1% (95% CI 80.7%-99.3%). Other MRI parameters have been used for adenomyosis diagnosis, but their diagnostic performance is unknown. Few studies attempted to correlate adenomyosis MRI phenotype to clinical outcomes.

CONCLUSIONS

A wide range of objective parameters for adenomyosis exist on MRI; however, in many cases their individual diagnostic performance remains uncertain. JZ characteristics remain the most widely used and investigated with acceptable diagnostic accuracy. Specific research is needed into how these objective measures of adenomyosis can be correlated to clinical outcomes.

Influence of menstrual status and pathological type on the apparent diffusion coefficient in cervical cancer: a primary study

BACKGROUND

Apparent diffusion coefficient (ADC) value is an important quantitative parameter in the research of cervical cancer, affected by some factors.

PURPOSE

To investigate the effect of pathological type and menstrual status on the ADC value of cervical cancer.

MATERIAL AND METHODS

A total of 352 individuals with pathologically confirmed cervical cancer between January 2015 to December 2017 were retrospectively enrolled in this study, including 317 cases with squamous cell carcinomas (SCC) and 35 cases with adenocarcinomas (AC); 177 patients were non-menopausal and 175 were menopausal. All patients underwent a routine 3.0-T magnetic resonance imaging (MRI) scan and diffusion-weighted imaging (DWI) examination using b-values of 0, 800, and 1000 s/mm². Three parameters including mean ADC (ADC_mean), maximum ADC (ADC_max), and minimum ADC (ADC_min) of cervical cancer lesions were measured and retrospectively analyzed. Independent samples t-test was used to compare the difference of ADC values in different menstrual status and pathological types.

RESULTS

In all menopausal and non-menopausal patients, the ADC_mean and ADC_min values of SCC were lower than those of AC (P<0.05), the ADC_max of two pathological types showed no statistical difference (P > 0.05). In menopausal patients, the ADC_mean, ADC_max, and ADC_min values of SCC were not statistically different compared with those of AC (P > 0.05). The ADC_mean, ADC_max, and ADC_min values of different pathological types cervical cancers in non-menopausal patients were all higher than those in menopausal patients (P<0.05).

CONCLUSION

The ADC values of the cervical cancers were different in different pathological types and were also affected by menstrual status.

Diffusion-Tensor Imaging of Uterine Cervical Carcinoma: Correlation With Histopathologic Findings

The authors investigated the usefulness of diffusion-tensor imaging (DTI) for evaluating tumor invasion depth, histologic grade, and lymph node metastasis in patients with cervical carcinoma (CC). Fifteen consecutive patients with histologically confirmed CC underwent 1.5-T magnetic resonance imaging and DTI. The CCs were clearly depicted as hypointense areas on all DTI maps. Fractional anisotropy, mean diffusivity, and axial diffusivity showed significantly inverse correlations with CC histologic grades and were significantly different between metastatic and nonmetastatic lymph nodes.

Augmented Reality with Diffusion Tensor Imaging and Tractography during Laparoscopic Myomectomies

Augmented reality is a technology that allows a surgeon to see key hidden subsurface structures in an endoscopic video in real-time. This works by overlaying information obtained from preoperative imaging and fusing it in real-time with the endoscopic image. Magnetic resonance diffusion tensor imaging (DTI) and fiber tractography are known to provide additional information to that obtained from standard structural magnetic resonance imaging (MRI). Here, we report the first 2 cases of the use of real-time augmented reality during laparoscopic myomectomies with visualization of uterine muscle fibers after DTI tractography-MRI to help the surgeon decide the starting point incision. In the first case, a 31-year-old patient was undergoing laparoscopic surgery for a 6-cm FIGO type V myoma. In the second case, a 38-year-old patient was undergoing a laparoscopic myomectomy for a unique 6-cm FIGO type VI myoma. Signed consent forms were obtained from both patients, which included clauses of no modification of the surgery. Before surgery, MRI was performed. The external surface of the uterus, the uterine cavity, and the surface of the myomas were delimited on the basis of the findings of preoperative MRI. A fiber tracking algorithm was used to extrapolate the uterine muscle fibers' architecture. The aligned models were blended with each video frame to give the impression that the uterus is almost transparent, enabling the surgeon to localize the myomas and uterine cavity exactly. The uterine muscle fibers were also displayed, and their visualization helped us decide the starting incision point for the myomectomies. Then, myomectomies were performed using a classic laparoscopic technique. These case reports show that augmented reality and DTI fiber tracking in a uterus with myomas are possible, providing fiber direction and helping the surgeon visualize and decide the starting incision point for laparoscopic myomectomy. Respecting the fibers' orientation could improve the quality of the scar and decrease the architectural disorganization of the uterus.

re: Diffusion Tensor Imaging (DTI) of the Cesarean-Scarred Uterus in vivo at 3T: Comparison Study of DTI Parameters Between Nonpregnant and Pregnant Cases

LEVEL OF EVIDENCE

5 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:131-132.

Diffusion Tensor Imaging (DTI) of the Cesarean-Scarred Uterus in vivo at 3T: Comparison Study of DTI Parameters Between Nonpregnant and Pregnant Cases

BACKGROUND

Fiber architecture of the human uterus can be depicted in vivo using 3T MR-DTI (diffusion tensor imaging).

PURPOSE

To investigate the differences in fibrous structure and DTI-related parameters between nonpregnant and pregnant cases in vivo.

STUDY TYPE

Prospective case-control study.

SUBJECTS

Thirty-one subjects were divided into two groups; 18 nonpregnant volunteers with previous cesarean deliveries (Group 1) and 13 patients in early pregnancy also with previous cesarean section (Group 2).

FIELD STRENGTH/SEQUENCE

3T Ssh-EPI (single-shot echo planar imaging) fast sequence with b values of 0 and 600 s/mm² along 30 directions.

ASSESSMENT

Fiber density, fiber length, apparent diffusion coefficient (ADC) value, and the fractional anisotropy (FA) value measured in the mid-sagittal plane of the uterus were obtained from the outer myometrium (OM), junctional zone (JZ), and the cesarean section scar (CSS). Fiber architecture in vivo was depicted by 3D diffusion tensor tractography (DTT).

STATISTICAL TESTS

A t-test of independent sample or Wilcoxon rank sum test were used for comparison.

RESULTS

Pregnant scarred-uterus (Group 2) showed a decrease in fiber density, FA value, and an increase in fiber length, ADC value than the nonpregnant scarred-uterus (Group 1) on OM, JZ, and CSS. Among the above parameters between the two groups, for OM, significant differences were found in fiber density (P < 0.001), length (P = 0.0306), and ADC (P = 0.0039). For JZ, significant differences were found in fiber density (P = 0.0093), FA (P = 0.0002), and ADC (P < 0.001). The scar's fiber density (P = 0.0794), length (P = 0.6167), FA (P = 0.6305), and ADC value (P = 0.1865) showed no statistically significant difference during early pregnancy.

DATA CONCLUSION

Our results indicate considerable diffusional changes in uterine fiber architecture during pregnancy. The microenvironment of scar tissue appears to change little during early pregnancy.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:124-130.

Variability of apparent diffusion coefficient in the brain in women during follicular and luteal phases of the menstrual cycle

PURPOSE

To investigate the variability of apparent diffusion coefficient (ADC) in the brain in women during follicular and luteal phases of the menstrual cycle.

METHODS

The present study included 32 females of reproductive age with regular menstruation. The participants were divided into two groups as group 1: females in the follicular phase, and group 2: females in the luteal phase. The regions of interest were manually drawn on the structures of the T2-weighted images (frontal gray and white matter, parietal gray and white matter, temporal gray and white matter, occipital gray and white matter, cerebellar gray and white matter, caudate nucleus, putamen, thalamus, internal capsule, pons, cerebrospinal fluid (CSF) in the frontal and in the occipital horn of the lateral ventricle and CSF in the middle part of the lateral ventricle). ADC values were averaged for each patient. We used Kruskal-Wallis ANOVA for more than two groups but used Mann Whitney U test for comparison of ADC values between the group of 18 females in the follicular phase and the group of 14 females in the luteal phase.

RESULTS

No statistically significant differences were observed among the groups in terms of the ADC value of each neuroanatomic structure that was evaluated.

CONCLUSION

We did not determine a significant difference among volunteers at the two different phases of the menstrual cycle in terms of ADC values measured from different regions of the brain. However, although not statistically significant, ADC values measured from almost all parts of the brain were higher at the luteal phase than at the follicular phase.

Diffusion tensor imaging beyond brains: Applications in abdominal and pelvic organs

Functional magnetic resonance imaging (MRI) provided critical functional information in addition to the anatomic profiles offered by conventional MRI, and has been enormously used in the initial diagnosis and followed evaluation of various diseases. Diffusion tensor imaging (DTI) is a newly developed and advanced technique that measures the diffusion properties including both diffusion motion and its direction in situ, and has been extensively applied in central nerve system with acknowledged success. Technical advances have enabled DTI in abdominal and pelvic organs. Its application is increasing, yet remains less understood. A systematic overview of clinical application of DTI in abdominal and pelvic organs such as liver, pancreas, kidneys, prostate, uterus, etc., is therefore presented. Exploration of techniques with less artifacts and more normative post-processing enabled generally satisfactory image quality and repeatability of measurement. DTI appears to be more valuable in the evaluation of diffused diseases of organs with highly directionally arranged structures, such as the assessment of function impairment of native and transplanted kidneys. However, the utility of DTI to diagnose focal lesions, such as liver mass, pancreatic and prostate tumor, remains limited. Besides, diffusion of different layers of the uterus and the fiber structure disruption can be depicted by DTI. Finally, a discussion of future directions of research is given. The underlying heterogeneous pathologic conditions of certain diseases need to be further differentiated, and it is suggested that DTI parameters might potentially depict certain pathologic characterization such as cell density. Nevertheless, DTI should be better integrated into the current multi-modality evaluation in clinical practice.

Diffusion Tensor Imaging of the Uterine Zones Related to the Menstrual Cycle and Menopausal Status at 3 Tesla MRI

BACKGROUND

Diffusion and diffusion tensor imaging techniques (DTI) are widely available and used both in central nervous system and body imaging, including gynecological diseases.

AIMS

The aims of this study were to assess the capability of DTI of uterine zones in relation to the menstrual cycle and ascertain the normal apparent diffusion coefficient and fractional anisotropy values at 3T magnetic resonance imaging (MRI).

STUDY DESIGN

Prospective clinical study.

METHODS

A total of 13 young reproductive and 12 postmenopausal healthy volunteers were included in the study. MRI examination included sagittal T2-weighted and single-shot echo planar imaging DTI obtained under free breathing. Fractional anisotropy (FA) values of the endometrium, junctional zone, and myometrium were determined.

RESULTS

The median (minimum-maximum) FA of the endometrium, myometrium, and junctional zone of the reproductive group were 0.31 (0.260-0.465), 0.42 (0.302-0.664), and 0.58 (0.420-0.745), respectively, in the proliferative phase and 0.26 (0.180-0.413), 0.48 (0.357-0.656), and 0.59 (0.490-0.675)], respectively, in the secretory phase. In the postmenopausal group, the FA values of the endometrium, myometrium, and junctional zone were 0.275 (0.136-0.425), 0.255 (0.191-0.553), and 0.27 (0.129-0.397), respectively. Apparent diffusion coefficient (ADC) values of the endometrium, myometrium, and junctional zone of the reproductive group were 1.25±0.254 (0.970-1.463), 1.67 (1.213-1.854), and 1.23 (0.853-1.301), respectively, in the proliferative phase and 1.32±0.283 (1.165-1.706), 1.55 (1.360-1.791), and 1.17 (1.163-1.705), respectively, in the secretory phase. In the postmenopausal group, the ADC values of the endometrium, myometrium, and junctional zone were measured as 1.100±0.192 (0.850-1.302), 1.14 (0.864-1.283), and 1.09 (0.912-1.291). The FA values of the endometrium and myometrium were lower in the secretory phase of the reproductive group, while ADC values were higher. However, both the FA and ADC values were lower in the postmenopausal group.

CONCLUSION

The present study showed that uterine DTI is feasible when used quantitatively. While FA values tend to decrease, ADC values increase significantly in all zones in the secretory phase except the junctional zone. Zonal FA and ADC values of postmenopausal women are lower in comparison to those in young women.