Field-of-view optimized and constrained undistorted single shot intravoxel incoherent motion diffusion-weighted imaging of the cervix during the menstrual cycle: A prospective study

OBJECTIVE

To provide insight into the biological characteristics of the healthy cervix by defining intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) parameters across the menstrual cycle.

METHODS

Forty-three females of reproductive age (18-45 years old) were included in this prospective study. Conventional magnetic resonance imaging (MRI) and IVIM-DWI scans were performed at multiple time-points across the menstrual cycle: T1 (menses), T2 (follicular phase), T3 (luteal phase). Intra- and interobserver repeatability of the IVIM-DWI values were evaluated with intraclass correlation coefficients (ICC), and D* was excluded from the analyses due to poor repeatability. Differences in each IVIM-DWI parameter among T1, T2, and T3 were explored. Subjects were stratified by age and parity for subgroup analyses (younger [18 - < 30 years] vs. older [≥30-45 years]; parity 0 vs. parity 1 and 2). Correlations between subject age and IVIM-DWI parameters were assessed. The overlap for each IVIM-DWI parameter among T1, T2, and T3 was evaluated.

RESULTS

ADC and D values of the cervix were significantly lower at T3 compared with T1 (p = 0.02 and 0.03) or T2 (p < 0.01 and < 0.01). In younger subjects (n = 26), ADC and D values were significantly lower at T3 compared with T1 (p < 0.01 and p = 0.02) or T2 (p = 0.03 and p = 0.04). In older subjects (n = 17), ADC values were significantly higher at T2 compared with T1 (p = 0.01) or T3 (p = 0.01). There were significant differences in ADC values at T1 in subgroup analyses stratified by age and parity (both p < 0.01). There was a moderate correlation between age and ADC values at T1. Overlap for IVIM-DWI parameters across the menstrual cycle was >50%.

CONCLUSION

ADC and D values of the heathy cervix differed across the menstrual cycle. Age and parity may influence the ADC value.

Field-of-view optimized and constrained undistorted single-shot study of intravoxel incoherent motion and diffusion-weighted imaging of the uterus during the menstrual cycle: a prospective study

PURPOSE

This study aimed to compare the variability of the uterus during the menses phase (MP), follicular phase (FP), and luteal phase (LP) of the menstrual cycle using intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI).

METHODS

This prospective study was conducted at the Guangdong Provincial Hospital of Traditional Chinese Medicine between January 2022 and January 2023. Women of childbearing age (18-45 years) with appropriate progesterone levels were included in this study. Conventional magnetic resonance imaging and IVIM-DWI scans were performed during the MP, FP, and LP. The differences in IVIM-DWI-derived parameters between these phases were then compared, and the overlap was quantitatively described.

RESULTS

The apparent diffusion coefficient (ADC) and pure molecular diffusion coefficient (D) values from the endometrium, uterine junctional zone (UJZ), and myometrium indicated statistical differences between the MP and FP and the MP and LP (ADC: endometrium, both P < 0.001; UJZ, P = 0.008 and P < 0.001, respectively; myometrium, P = 0.033 and P = 0.006, respectively; D: endometrium, both P < 0.001; UJZ, P = 0.008 and P = 0.006, respectively; myometrium, P = 0.041 and P = 0.045, respectively). The perfusion-related diffusion coefficient (D*) values from the myometrium indicated statistical differences between the FP and MP and the FP and LP (D*: myometrium, P = 0.049 and P = 0.009, respectively). The overlapping endometrium ratios between the MP and FP or LP were lower than 50% in the ADC and D values (ADC: overlapping of MP and FP: 33.33%, overlapping of MP and LP: 23.33%; D: overlapping of MP and FP: 40.00%, overlapping of MP and LP: 43.33%).

CONCLUSION

The ADC and IVIM-derived parameters indicated differences in the uterus in diverse phases of the menstrual cycle, especially in the endometrium in relation to ADC and D values.

Adenomyosis at a Glance: An Integrated Review of Transvaginal Ultrasound and MR Imaging Findings

Adenomyosis is a benign uterine disorder increasingly recognized in premenopausal women. Given its significant clinical burden, an accurate noninvasive diagnosis is paramount. Both transvaginal ultrasound (TVUS) and magnetic resonance (MR) provide an adequate assessment of adenomyosis, the former being recommended for first-line imaging evaluation and the latter being mainly used as a problem-solving technique. In this article, the authors review the TVUS and MR imaging findings of adenomyosis while referring to their histopathological background. Whereas direct signs correlate directly to ectopic endometrial tissue and are highly specific to adenomyosis, indirect signs result from myometrial hypertrophy and increase diagnostic sensitivity. Potential pitfalls, differential diagnoses, and frequently associated estrogen-dependent conditions are also discussed.

Magnetic resonance imaging findings of cystic ovarian tumors: major differential diagnoses in five types frequently encountered in daily clinical practice

There are many types of ovarian tumors, and these different types often form cystic masses with a similar appearance, which can make their differentiation difficult. However, with the exclusion of rare ovarian tumors, the number of ovarian tumors encountered in daily practice is somewhat fixed. It goes without saying that magnetic resonance imaging (MRI) is useful for differentiating ovarian tumors. In this review, we summarize the differential diagnoses for each of the five types of MRI findings commonly encountered in daily practice. First, unilocular cystic masses without mural nodules/solid components include benign lesions such as serous cystadenoma, functional cysts, surface epithelial inclusion cysts, paratubal cysts, and endometriosis. Second, multilocular cystic ovarian lesions include mucinous tumors and ovarian metastases. It should be noted that mucinous tumors may be diagnosed as borderline or carcinoma, even if no solid component is observed. Third, cystic lesions with mural nodules that are unrelated to endometriosis include serous borderline tumor and serous carcinoma. Cystic lesions with solid components are more likely to be malignant, but some may be diagnosed as benign. Fourth, ovarian tumors deriving from endometriosis include seromucinous borderline tumors, endometrioid carcinoma, and clear cell carcinoma. These tumors sometimes need to be differentiated from serous tumors. Finally, cystic lesions with lipid contents include teratoma-related tumors. In mature cystic teratoma, mural nodules (called "Rokitansky protuberance" or "dermoid nipple") are sometimes seen, but they do not suggest malignancy. Some of these lesions can be diagnosed accurately by considering their characteristic imaging findings, their changes over time, MRI findings other than those of the primary lesion, and information from other modalities such as tumor markers. To ensure the optimal treatment for ovarian tumors, it is important to estimate the histological type as well as to diagnose whether a lesion is benign or malignant.

Magnetic Resonance Imaging of Acute Abdominal Pain in the Pregnant Patient

Evaluation of a pregnant patient presenting with acute abdominal pain can be challenging to accurately diagnose for a variety of reasons, and particularly late in pregnancy. Noncontrast MR remains a safe and accurate diagnostic imaging modality for the pregnant patient presenting with acute abdominal pain, following often an initially inconclusive ultrasound examination, and can be used in most settings to avoid the ionizing radiation exposure of a computed tomography scan. Pathologic processes discussed in this article include some of the more common gastrointestinal, hepatobiliary, genitourinary, and gynecologic causes of abdominal pain occurring in pregnancy, as well as traumatic injuries.

Uterine leiomyomas revisited with review of literature

Uterine leiomyomas, more commonly known as fibroids, are the most common neoplasms of the uterus. These tumors have a profound effect on health care and cost worldwide. Depending on the race, uterine leiomyomas can be seen in 70-80% of all women. Although majority of the women with uterine leiomyomas remain asymptomatic, approximately 30% can present with symptoms. Diagnosing typical leiomyomas on imaging is straightforward. However, when large, located extrauterine and especially with degeneration, the diagnosis can be challenging on imaging. In this article, apart from reviewing the demographics and management of patients with leiomyomas, we describe in detail the imaging appearance of various atypical leiomyomas, uncommon locations outside the uterus and their important differential diagnosis that can have a profound effect on patient management.

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.

MRI Findings and Differential Diagnosis of Benign and Malignant Tumors of the Uterine Corpus

자궁은 크게 자궁체부와 자궁경부로 나뉜다. 이 중 자궁내막과 자궁근층으로 이루어진 자궁체부에는 양성에서 악성 종양까지 다양한 질환이 발생한다. 비침습적인 일차적 평가로 초음파와 컴퓨터단층촬영이 있으나 비특이적인 영상 소견으로 감별이 어려운 경우가 있다. 반면높은 해상도와 병리학적 특성 파악이 가능한 자기공명영상은 병변의 위치 확인뿐만 아니라 조직학적 특징, 그 리고 악성 종양의 병기 설정에도 도움을 준다. 이 종설에서는 영상의학과의사들이 알아야 할 자궁체부에서 볼 수 있는 다양한 양성과 악성 종양들의 특징적인 자기공명영상 소견들과 이들의 감별점에 대해 정리했다.

Automatic segmentation of the uterus on MRI using a convolutional neural network

BACKGROUND

This study was performed to evaluate the clinical feasibility of a U-net for fully automatic uterine segmentation on MRI by using images of major uterine disorders.

METHODS

This study included 122 female patients (14 with uterine endometrial cancer, 15 with uterine cervical cancer, and 55 with uterine leiomyoma). U-net architecture optimized for our research was used for automatic segmentation. Three-fold cross-validation was performed for validation. The results of manual segmentation of the uterus by a radiologist on T2-weighted sagittal images were used as the gold standard. Dice similarity coefficient (DSC) and mean absolute distance (MAD) were used for quantitative evaluation of the automatic segmentation. Visual evaluation using a 4-point scale was performed by two radiologists. DSC, MAD, and the score of the visual evaluation were compared between uteruses with and without uterine disorders.

RESULTS

The mean DSC of our model for all patients was 0.82. The mean DSCs for patients with and without uterine disorders were 0.84 and 0.78, respectively (p = 0.19). The mean MADs for patients with and without uterine disorders were 18.5 and 21.4 [pixels], respectively (p = 0.39). The scores of the visual evaluation were not significantly different between uteruses with and without uterine disorders.

CONCLUSIONS

Fully automatic uterine segmentation with our modified U-net was clinically feasible. The performance of the segmentation of our model was not influenced by the presence of uterine disorders.

Radiological appearances of corpus luteum cysts and their imaging mimics

PURPOSE

To review the radiological appearances of corpus luteum cysts and their imaging mimics.

CONCLUSION

Corpus luteum cysts are normal post-ovulatory structures seen in the ovaries through the second half of the menstrual cycle and the first trimester of pregnancy. The typical appearance, across all modalities, is of a 1- to 3-cm cyst with a thick crenulated vascularized wall. Occasionally, similar imaging findings may be seen with endometrioma, ectopic pregnancy, tuboovarian abscess, red degeneration of a fibroid, and ovarian neoplasia. In most cases, imaging findings are distinctive and allow for a confident and accurate diagnosis that provides reassurance for patients and referring physicians and avoids costly unnecessary follow-up.

Differentiation between pelvic abscesses and pelvic tumors with diffusion-weighted MR imaging: a preliminary study

PURPOSE

Use diffusion-weighted magnetic resonance imaging (MRI) in differentiating pelvic abscess from pelvic cystic tumor.

MATERIALS AND METHODS

Patients with pelvic abscess (n=23) or pelvic cystic tumor (n=15) who underwent diffusion-weighted MRI were reviewed.

RESULTS

Pelvic abscesses showed hyperintensity on diffusion-weighted MRI and hypointensity on apparent diffusion coefficient (ADC) map. The mean ADC values of fluid in pelvic abscess and pelvic tumors were 0.73 ± 0.15 × 10(-3) and 2.27 ± 0.45 × 10(-3) mm(2)/s, respectively. Pelvic abscesses had significantly lower ADC values than pelvic cystic tumors (P<.001).

CONCLUSION

Diffusion-weighted MRI provides a noncontrast method for interpreting pelvic cystic lesions.

Diffusion-weighted magnetic resonance imaging of the normal endometrium: temporal and spatial variations of the apparent diffusion coefficient

BACKGROUND

Diffusion-weighted magnetic resonance imaging (DWI) is increasingly used in the diagnosis of endometrial disease. No complete knowledge, however, exists yet of the influence of physiology on the endometrial apparent diffusion coefficient (ADC) values on which DWI is based.

PURPOSE

To establish whether the ADC values measured with DWI in the endometrium of healthy reproductive-aged women significantly vary from the early proliferative to the periovulatory phase of the menstrual cycle and between the fundus and the isthmus of the uterus.

MATERIAL AND METHODS

In 17 women the endometrial ADC values measured on the fifth menstrual day, both at the fundus and at the isthmus of the uterus, were compared to the values obtained on the 14th day before the subsequent cycle. In 81 women (menstrual day: fifth through 21st) the endometrial ADC values measured at the fundus were compared to the values obtained at the isthmus of the uterus. All examinations were performed with a 1.5 T magnet (b values: 0 and 800 mm/s(2)). The results were analyzed by means of Student's t-test per paired data.

RESULTS

The endometrial ADC values measured on the fifth day of the menstrual cycle were lower than those obtained in the periovulatory phase both at the fundus (mean 0.923 vs. 1.256 × 10(-3) mm(2)/s) and at the isthmus (mean 1.297 vs. 1.529 × 10(-3) mm(2)/s) of the uterus. The endometrial ADC values measured at the fundus of the uterus were lower than those obtained at the isthmus (mean 1.132 vs. 1.420 × 10(-3) mm(2)/s) through the menstrual cycle. All these differences were highly significant (P < 0.001) at statistical analysis.

CONCLUSION

Physiological variations occurring in endometrial ADC values of healthy women should be considered by the radiologists when interpreting DWI examinations in patients with endometrial disease.

Magnetic resonance manifestations of hyperreactio luteinalis

OBJECTIVE

Hyperreactio luteinalis (HL) is a rare benign physiological ovarian enlargement associated with gestational trophoblastic disease or pregnancy, and may mimic neoplasm. We evaluated magnetic resonance findings of HL to distinguish from neoplasm by using diffusion-weighted imaging with apparent diffusion coefficient (ADC) measurement.

METHODS

Magnetic resonance manifestations of 15 cases of HL in 8 women (mean age, 32 years) were retrospectively evaluated. Diffusion-weighted imaging (b = 0 and 800 seconds/mm²) was obtained in 11 cases of HL, and ADC was compared with that in solid portions of 18 ovarian cancers.

RESULTS

All cases of HL appeared as multilocular cystic masses with septations mimicking mucinous cystic tumors. Intervening ovarian stroma exhibited hyperintensity on diffusion-weighted imaging. The ADC in ovarian stroma in HL was significantly higher than that in solid portions of ovarian cancers.

CONCLUSION

Ovarian stroma in HL may mimic solid tumorous components in mucinous tumors; however, high ADC reflecting edematous, luteinized stroma may be helpful for the diagnosis of HL.