European Journal of Cardiovascular Medicine

Uterine fibroids, also known as leiomyomas, are the most common benign tumors of the female reproductive system, affecting up to 70-80% of women by the age of 50.^[1] While many fibroids are asymptomatic, they can cause significant morbidity, including heavy menstrual bleeding, pelvic pain, and reproductive complications.^[2] Accurate diagnosis and characterization of uterine fibroids are crucial for appropriate management and treatment planning.

Traditionally, transvaginal ultrasonography has been the primary imaging modality for the initial evaluation of uterine fibroids due to its wide availability, cost-effectiveness, and lack of ionizing radiation.^[3] However, ultrasound has limitations in detecting small fibroids, differentiating between fibroids and other uterine pathologies, and accurately assessing the size and location of multiple fibroids.^[4]

Magnetic Resonance Imaging (MRI) has emerged as a powerful tool in the evaluation of uterine fibroids, offering superior soft-tissue contrast and multiplanar imaging capabilities.^[5] MRI can provide detailed information about fibroid size, location, and number, as well as detect coexisting uterine pathologies such as adenomyosis.^[6] However, MRI is more expensive and less readily available than ultrasound, raising questions about its cost-effectiveness and appropriate use in clinical practice.^[7]

While several studies have compared ultrasound and MRI in the diagnosis of uterine fibroids, results have been inconsistent, and most studies have been conducted in Western populations.^{[8, 9]} There is a paucity of data from the Indian subcontinent, where the prevalence and presentation of uterine fibroids may differ due to genetic and environmental factors.^[10]

This study aims to compare the diagnostic accuracy of ultrasound and MRI in detecting and characterizing uterine fibroids in a cohort of Indian women. By assessing the relative strengths and limitations of each imaging modality, we seek to provide evidence-based guidance for the optimal use of these imaging techniques in the evaluation of uterine fibroids, particularly in the context of resource-limited settings.

Study Design and Setting: This cross-sectional study was conducted at NMCH Hospital in association with Primescan Imaging and Diagnostic Centre in Patna, Bihar, India, from February 2023 to January 2024.

Study Population: A total of 100 women aged 25-55 years with clinically suspected uterine fibroids were consecutively recruited. Inclusion criteria were: premenopausal women, clinical symptoms suggestive of uterine fibroids (e.g., heavy menstrual bleeding, pelvic pain, or pressure symptoms), and willingness to undergo both ultrasound and MRI examinations. Exclusion criteria included:  pregnancy, history of uterine surgery within the past 6 months, known contraindications to MRI, and  inability to provide informed consent.

Imaging Protocols for Ultrasound Examination: All participants underwent transvaginal ultrasonography using a Ultrasound Machine (GE Voluson S10 expert) with a 5-9 MHz endovaginal probe. Transabdominal scanning was performed when necessary using a 3-5 MHz convex probe. A standardized protocol was followed, including evaluation of the uterus in sagittal and transverse planes. The number, size, location, and echogenicity of fibroids were recorded. All ultrasound examinations were performed by experienced radiologists with at least 5 years of experience in gynecological imaging.

MRI Examination: MRI was performed using a 1.5-Tesla MRI scanner [Siemens Magneton Sempra] at Primescan Imaging. The MRI protocol included T1-weighted, T2-weighted, and contrast-enhanced T1-weighted sequences in axial, sagittal, and coronal planes. Gadolinium-based contrast agent was administered intravenously at a dose of 0.1 mmol/kg body weight. MRI images were interpreted by radiologists with expertise in pelvic MRI, who were blinded to the ultrasound findings.

Data Collection and Analysis: For each imaging modality, the following data were recorded: number of fibroids, size of the largest fibroid, location of fibroids (intramural, subserosal, submucosal, or pedunculated), and presence of any additional findings such as adenomyosis or fibroid degeneration. The diagnostic performance of ultrasound and MRI was assessed using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Statistical Analysis: Data were analyzed using SPSS version 25.0. Descriptive statistics were used to summarize patient demographics and imaging findings. The McNemar test was used to compare the detection rates of fibroids between ultrasound and MRI. The Wilcoxon signed-rank test was used to compare the number and size of fibroids detected by each modality. Kappa statistics were calculated to assess agreement between ultrasound and MRI for fibroid location. A p-value < 0.05 was considered statistically significant.

Inter-observer Reliability: To assess inter-observer reliability, a subset of 20 randomly selected cases was independently reviewed by a second radiologist for both ultrasound and MRI. Intraclass correlation coefficients (ICC) were calculated for continuous variables, and kappa statistics for categorical variables.

Ethical Considerations

This study was approved by the Institutional Ethics Committee. Written informed consent was obtained from all participants after explaining the study's purpose, procedures, and potential risks. Patient confidentiality was maintained through data de-identification and secure storage.

Our study included 100 patients with a mean age of 39.7 years (SD ± 7.3, range 25-55 years) (Table No:1).

Fibroid Detection and Characterization: Ultrasound detected uterine fibroids in 82% of patients, while MRI identified fibroids in 93% of cases (Table 2). MRI demonstrated superior capability in detecting multiple fibroids, with a mean of 3.1 fibroids per patient (range: 0-12) compared to 2.3 fibroids per patient (range: 0-8) detected by ultrasound. The mean diameter of the largest fibroid was slightly higher when measured by MRI (4.7 cm, range: 0.5-13.2 cm) compared to ultrasound (4.2 cm, range: 0.8-12.5 cm) (Table 3).

Fibroid Location: Both imaging modalities showed similar distribution patterns of fibroid locations. Intramural fibroids were most common, followed by subserosal, submucosal, and pedunculated fibroids. MRI identified a slightly higher percentage of intramural (48% vs. 45%) and pedunculated (6% vs. 5%) fibroids compared to ultrasound (Table 4). Cervical and lower segment fibroids could not be mapped properly with USG. This limitation was addressed by MRI suggesting its better aid in mapping of fibroids to facilitate further surgical planning.

FIG 1: MRI image of huge cervical fibroid involving the lower uterine segment.

Diagnostic Accuracy: MRI demonstrated superior diagnostic accuracy across all measures. The sensitivity and specificity of MRI (98.9% and 97.1%, respectively) were higher than those of ultrasound (88.2% and 85.7%, respectively). Similarly, MRI showed higher positive and negative predictive values (99.0% and 95.7%) compared to ultrasound (97.6% and 54.5%) (Table 5). We correlated the TVS, MRI and intra-op images of fibroids. MRI gave a clear idea of exact location of fibroid or fibroids in cases of multiple fibroids facilitating to decide the mode of surgery and intra-op precautions.  Adenomyoma closely resembled fibroid in TVS but could be ascertained with surety only with MRI. We correlated these with intra-op findings in patients who were taken up for surgery mostly by laparoscopy.

FIG 2: TVS image of uterus with posterior wall myoma.

FIG 3: MRI images of posterior wall myoma of the same patient.  A, B,C represents T2 mid-sagittal , coronal and axial section of pelvis respectively eliciting left postero-lateral panmural myoma abutting the endometrial cavity.

FIG 4: INTRA-OP IMAGE OF SAME PATIENT. D & E are stills taken during laparoscopic myomectomy of this patient.

Discrepancies and Additional Findings: MRI detected fibroids in 11 cases (11%) that were not identified by ultrasound, while ultrasound detected fibroids in 2 cases (2%) that were not confirmed by MRI. Additionally, MRI identified adenomyosis in 15 patients (15%) that was not detected by ultrasound. MRI also provided better characterization of fibroid degeneration in 23 cases (23%) (Table 6).

FIG 5: MRI images of posterior focal adenomyoma. A, B, C represents T2 sagittal, coronal and axial  section of pelvis respectively eliciting right postero-lateral focal adenomyoma pushing the endometrial cavity anteriorly. There are extensive adhesions between posterior surface of uterus and rectum but fat planes are well preserved.

FIG 6: Intra-op findings of the same patient. Fig D depicts extensive posterior adhesion of uterus with rectum and sigmoid. Fig E elicits the posterior focal adenomyoma being removed by laparoscopic adenomyomectomy after meticulous adhesiolysis. MRI facilitated to identify the correct plane and plan the depth of incision.

Table 1: Patient Demographics

Table 2: Fibroid Detection

Table 3: Number and Size of Fibroids Detected

Table 4: Location of Fibroids

Table 5: Diagnostic Accuracy

Table 6: Discrepancies and Additional Findings

FIG 7: Fibroid Detection by Imaging Modality

FIG 8: Location of Fibroids Detected by Ultrasound and MRI

FIG 9: Diagnostic Accuracy of Ultrasound and MRI

This study compared the diagnostic performance of ultrasound and MRI in the detection and characterization of uterine fibroids in a cohort of 100 Indian women. Our findings demonstrate that while both imaging modalities are effective in diagnosing uterine fibroids, MRI offers superior diagnostic accuracy and provides additional valuable information.

The higher detection rate of fibroids by MRI (93%) compared to ultrasound (82%) is consistent with previous studies [11]. This difference is likely due to MRI's superior soft tissue contrast and multiplanar imaging capabilities, which allow for better visualization of small fibroids and those in challenging locations [12]. The ability of MRI to detect an average of 3.1 fibroids per patient, compared to 2.3 by ultrasound, further underscores its sensitivity in identifying multiple lesions.

The superior diagnostic accuracy of MRI, as evidenced by its higher sensitivity (98.9% vs. 88.2%) and specificity (97.1% vs. 85.7%), suggests that it may be particularly valuable in cases where precise fibroid mapping is crucial, such as in preoperative planning for myomectomy or in patients considering uterine artery embolization [13]. The notably higher negative predictive value of MRI (95.7% vs. 54.5% for ultrasound) indicates its potential utility in reliably excluding the presence of fibroids.

Our finding that MRI detected fibroids in 11% of cases missed by ultrasound highlights its role in diagnosing fibroids in patients with equivocal ultrasound results. This is particularly relevant in cases of adenomyosis, which MRI identified in 15% of patients not detected by ultrasound. The ability to differentiate between fibroids and adenomyosis is crucial for appropriate management, as these conditions may require different treatment approaches [14].

The better characterization of fibroid degeneration by MRI in 23% of cases is another significant advantage. This information can be valuable in predicting the response to certain treatments, such as uterine artery embolization, and in differentiating degenerating fibroids from other pathologies.

Despite these advantages, it is important to consider the cost-effectiveness and availability of MRI, especially in resource-limited settings. Ultrasound remains a valuable first-line imaging modality due to its wide availability, lower cost, and real-time imaging capabilities. Our results suggest that ultrasound is still effective in detecting the majority of clinically significant fibroids.

The strengths of this study include its prospective design, the use of standardized imaging protocols, and the blinded interpretation of images. However, limitations include the lack of surgical or histopathological confirmation of all imaging findings and the potential for selection bias due to the inclusion of women with suspected fibroids.

While both ultrasound and MRI are effective in diagnosing uterine fibroids, MRI demonstrates superior diagnostic accuracy and provides additional valuable information about fibroid characteristics and associated uterine pathologies. These findings suggest that MRI may be particularly beneficial in complex cases, preoperative planning, and when ultrasound results are inconclusive. Future studies should focus on the cost-effectiveness of MRI in various clinical scenarios and its impact on treatment outcomes.

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