Prediction of histopathologic features and proliferative activity of uterine leiomyoma by magnetic resonance imaging prior to GnRH analogue therapy: correlation between T2-weighted images and effect of GnRH analogue

Prediction of non-perfusion volume ratio for uterine fibroids treated with ultrasound-guided high-intensity focused ultrasound based on MRI radiomics combined with clinical parameters

BACKGROUND

Prediction of non-perfusion volume ratio (NPVR) is critical in selecting patients with uterine fibroids who will potentially benefit from ultrasound-guided high-intensity focused ultrasound (HIFU) treatment, as it reduces the risk of treatment failure. The purpose of this study is to construct an optimal model for predicting NPVR based on T2-weighted magnetic resonance imaging (T2MRI) radiomics features combined with clinical parameters by machine learning.

MATERIALS AND METHODS

This retrospective study was conducted among 223 patients diagnosed with uterine fibroids from two centers. The patients from one center were allocated to a training cohort (n = 122) and an internal test cohort (n = 46), and the data from the other center (n = 55) was used as an external test cohort. The least absolute shrinkage and selection operator (LASSO) algorithm was employed for feature selection in the training cohort. The support vector machine (SVM) was adopted to construct a radiomics model, a clinical model, and a radiomics-clinical model for NPVR prediction, respectively. The area under the curve (AUC) and the decision curve analysis (DCA) were performed to evaluate the predictive validity and the clinical usefulness of the model, respectively.

RESULTS

A total of 851 radiomic features were extracted from T2MRI, of which seven radiomics features were screened for NPVR prediction-related radiomics features. The radiomics-clinical model combining radiomics features and clinical parameters showed the best predictive performance in both the internal (AUC = 0.824, 95% CI 0.693-0.954) and external (AUC = 0.773, 95% CI 0.647-0.902) test cohorts, and the DCA also suggested the radiomics-clinical model had the highest net benefit.

CONCLUSIONS

The radiomics-clinical model could be applied to the NPVR prediction of patients with uterine fibroids treated by HIFU to provide an objective and effective method for selecting potential patients who would benefit from the treatment mostly.

Development of an Algorithm to Differentiate Uterine Sarcoma from Fibroids Using MRI and LDH Levels

BACKGROUND

This study aimed to establish an evaluation method for detecting uterine sarcoma with 100% sensitivity using MRI and serum LDH levels.

METHODS

One evaluator reviewed the MRI images and LDH values of a total of 1801 cases, including 36 cases of uterine sarcoma and 1765 cases of uterine fibroids. The reproducibility of the algorithm was also examined by four evaluators with different imaging experience and abilities, using a test set of 61 cases, including 14 cases of uterine sarcoma.

RESULTS

From the MRI images and LDH values of 1801 cases of uterine sarcoma and uterine fibroids, we found that all sarcomas were included in the group with a high T2WI and either a high T1WI, an unclear margin, or high LDH values. In addition, when cases with DWI were examined, all sarcomas had high DWI. Among the 36 sarcoma cases, the group with positive findings for T2WI, T1WI, margins, and serum LDH levels all had a poor prognosis (p = 0.015). The reproducibility of the algorithm was examined by four evaluators and the sensitivity of sarcoma detection ranged from 71% to 93%.

CONCLUSION

We established an algorithm to distinguish uterine sarcoma if tumors in the myometrium with low T2WI and DWI are present.

Histological findings in resected leiomyomas following MR-HIFU treatment, single-institution data from seven patients with unfavorable focal therapy

PURPOSE

Magnetic resonance - high-intensity focused ultrasound (MR-HIFU) is a noninvasive treatment option for symptomatic uterine leiomyomas. Currently, pretreatment MRI is used to assess tissue characteristics and predict the most likely therapeutic response for individual patients. However, these predictions still entail significant uncertainties. The impact of tissue properties on therapeutic outcomes remains poorly understood and detailed knowledge of the histological effects of ultrasound ablation is lacking. Investigating these aspects could aid in optimizing patient selection, enhancing treatment effects and improving treatment outcomes.

METHODS AND MATERIALS

We present seven patients who underwent MR-HIFU treatment for leiomyoma followed by second-line surgical treatment. Tissue samples obtained during the surgery were stained with hematoxylin and eosin, Masson's trichrome and Herovici to evaluate general morphology, fibrosis and collagen deposition of leiomyomas. Immunohistochemical CD31, Ki-67 and MMP-2 stainings were performed to study vascularization, proliferation and matrix metalloproteinase-2 protein expression in leiomyomas, respectively.

RESULTS

The clinical characteristics and radiological findings of the leiomyomas prior to treatment as well as qualitative histological findings after the treatment are presented and discussed in the context of current literature. A tentative model for volume reduction is presented.

CONCLUSION

These findings provide insights into potential factors contributing to suboptimal therapeutic outcomes and the variability in histological changes following treatment.

Development and validation of a combined model based on dual-sequence MRI radiomics for predicting the efficacy of high-intensity focused ultrasound ablation for hysteromyoma

OBJECTIVES

To determine the value of dual-sequence magnetic resonance imaging (MRI)-based radiomics in predicting the efficacy of high-intensity focused ultrasound (HIFU) ablation for hysteromyoma.

METHODS

A total of 142 patients with 172 hysteromyomas (95 hysteromyomas from the sufficient ablation group, and 77 hysteromyomas from the insufficient ablation group) were enrolled in the study. The clinical-radiological model was constructed with independent clinical-radiological risk factors, the radiomics model was constructed based on the optimal radiomics features of hysteromyoma from dual sequences, and the two groups of features were incorporated to construct the combined model. A fivefold cross validation procedure was adopted to validate these models. A nomogram was constructed, applying the combined model in the training cohort. The models were assessed with receiver operating characteristic (ROC) curves and integrated discrimination improvement (IDI). An independent test cohort comprising 40 patients was used to evaluate the performance of the optimal model.

RESULTS

Among the three models, the average areas under the ROC curves (AUC) of the radiomics model and combined model were 0.803 (95% confidence interval (CI): 0.726-0.881) and 0.841 (95% CI: 0.772-0.909), which were better than the clinical-radiological model in the training cohort. The IDI showed that the combined model had the best prediction accuracy. The combined model also showed good discrimination in both the validation cohort (AUC = 0.834) and the independent test cohort (AUC = 0.801).

CONCLUSION

The combined model based on the dual-sequence MRI radiomics is the most promising tool from our study to assist clinicians in predicting HIFU ablation efficacy.

Predictive value of image indexes of B-mode and power Doppler sonography on the efficacy of high intensity focused ultrasound ablation for uterine fibroids

OBJECTIVE

To investigate the value of the image indexes of B-mode and power Doppler sonography in predicting the therapeutic efficacy of high intensity focused ultrasound (HIFU) ablation for uterine fibroids.

MATERIALS AND METHODS

Two hundred and three patients with a solitary uterine fibroid were enrolled in this study. Every patient underwent transvaginal sonography (TVS) and magnetic resonance imaging (MRI) before HIFU. The patients were divided into hypointense, isointense and hyperintense fibroid groups based on T2 weighted MR imaging characteristics, and ultrasonic image indexes of the fibroids in different groups were compared. Multiple linear regression analysis was used to evaluate the correlation between ultrasonic image indexes and energy efficiency factor (EEF), non-perfused volume (NPV) ratio of uterine fibroids.

RESULTS

Among them, 72 patients had a hypointense fibroid, 70 had an isointense fibroid and 61 had a hyperintense fibroid. Significant differences were observed in the ultrasound imaging gray scale value difference between the myometrium and uterine fibroids (GSmyo-fib), the ultrasound imaging gray scale value ratio of fibroids over the myometrium (GSfib/myo), and the ratio of power Doppler pixel area to fibroid area (PDPA/FA) among the three groups (p < 0.05). Linear regression analysis showed that the PDPA/FA and the location of fibroids were the factors affecting the NPV ratio, a model for predicting the NPV ratio was established.

CONCLUSIONS

A model with the PDPA/FA for NPV ratio could be used to predict the therapeutic efficacy of HIFU for fibroids.

Feasibility of T2 relaxation time in predicting the technical outcome of MR-guided high-intensity focused ultrasound treatment of uterine fibroids

PURPOSE

The aim of this study was to assess the feasibility of T2 relaxation time in predicting the immediate technical outcome i.e., nonperfused volume ratio (NPVr) of magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) treatment of symptomatic uterine fibroids and to compare it with existing T2-weighted imaging methods (Funaki classification and scaled signal intensity, SSI).

MATERIALS AND METHODS

30 patients with 32 uterine fibroids underwent an MRI study including a quantitative T2 relaxation time measurement prior to MRgHIFU treatment. T2 relaxation times were measured with a multi-echo fast imaging-based technique with 16 echoes. The correlation between pretreatment values of the uterine fibroids and treatment outcomes, that is nonperfused volume ratios (NPVr), was assessed with nonparametric statistical measures. T2 relaxation time-based method was compared to existing T2-weighted imaging-based methods using receiver-operating-characteristics (ROC) curve analysis and Chi-square test.

RESULTS

Nonparametric measures of association revealed a statistically significant negative correlation between T2 relaxation time values and NPVr. The T2 relaxation time classification (T2 I, T2 II, and T2 III) resulted in the whole model p-value of 0.0019, whereas the Funaki classification resulted in a p-value of 0.56. The T2 relaxation time classification (T2 I and T2 II) achieved a whole model of a p-value of 0.0024, whereas the SSI classification had a p-value of 0.0749.

CONCLUSIONS

A longer T2 relaxation time of the fibroid prior to treatment correlated with a lower NPVr. Based on our results, the T2 relaxation time classifications seem to outperform the Funaki classification and the SSI method.

Ultrasound-guided high intensity focused ultrasound ablation for uterine fibroids: long-term outcomes and factors affecting local recurrence

OBJECTIVE

To assess the long-term outcomes and the factors affecting local recurrence of uterine fibroids after ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation.

MATERIALS AND METHODS

629 patients with a solitary uterine fibroid smaller than 10 cm in diameter treated with USgHIFU at our institutes between January 2011 and December 2016 were retrospectively analyzed. The patients were requested to take pre-HIFU and one day post-HIFU MRI. The patients were asked to return to the hospital every 3 months until January 2020, for imaging evaluation and to check on improvement in symptoms.

RESULTS

Five hundred and thirty-six patients completed follow-up according to our protocol. The median follow-up time was 69 (interquartile range: 48 to 89) months. Among them, local recurrence was detected in 110 patients. 18 (16.4%) patients required additional treatment between 12 and 24 months after USgHIFU treatment, 59 (53.6%) patients required additional treatment 24 months after USgHIFU. Therefore, in total, 77 patients required additional treatment, of which 32 received USgHIFU and 45 underwent myomectomy. The median non-perfused volume (NPV) ratio in patients with recurrence was 73%, compared to 89% among patients without recurrence. Multivariate analysis showed that NPV ratio, maximum fibroid diameter and fibroid enhancement type were the independent factors affecting the recurrence of fibroids after USgHIFU treatment.

CONCLUSIONS

Achievement of NPV ratio higher than 70% has led to acceptable re-intervention rate during the follow-up period after USgHIFU. NPV ratio, maximum fibroid diameter, and fibroid enhancement type were the independent factors affecting the recurrence of fibroids after USgHIFU treatment.

Feasibility of apparent diffusion coefficient in predicting the technical outcome of MR-guided high-intensity focused ultrasound treatment of uterine fibroids - a comparison with the Funaki classification

PURPOSE

To investigate the feasibility of using an apparent diffusion coefficient (ADC) classification in predicting the technical outcome of magnetic resonance imaging-guided high-intensity focused ultrasound (MRgHIFU) treatment of symptomatic uterine fibroids and to compare it to the Funaki classification.

MATERIALS AND METHODS

Forty-two patients with forty-eight uterine fibroids underwent diffusion-weighted imaging (DWI) before MRgHIFU treatment. The DW images were acquired with five different b-values. Correlations between ADC values and treatment parameters were assessed. Optimal ADC cutoff values were determined to predict technical outcomes, that is, nonperfused volume ratios (NPVr) such that three classification groups were created (NPVr of <30%, 30-80%, or >80%). Results were compared to the Funaki classification using receiver-operating-characteristic (ROC) curve analysis, with statistical significance being tested with the Chi-square test.

RESULTS

A statistically significant negative correlation (Spearman's ρ = -0.31, p-value < 0.05) was detected between ADC values and NPV ratios. ROC curve analysis indicated that optimal ADC cutoff values of 980 × 10^-6mm²/s (NPVr > 80%) and 1800 × 10^-6mm²/s (NPVr < 30%) made it possible to classify fibroids into three groups: ADC I (NPVr > 80%), ADC II (NPVr 30-80%) and ADC III (NPVr < 30%). Analysis of the whole model area under the curve resulted in values of 0.79 for the ADC classification (p-value = 0.0007) and 0.62 for the Funaki classification (p-value = 0.0527).

CONCLUSIONS

Lower ADC values prior to treatment correlate with higher NPV ratios. The ADC classification seems to be able to predict the NPV ratio and may even outperform the Funaki classification. Based on these results DWI and ADC maps should be included in the MRI screening protocol.

Uterine Artery Embolization of Uterine Leiomyomas: Predictive MRI Features of Volumetric Response

OBJECTIVE. The purpose of this article was to evaluate MRI features of uterine leiomyomas that predict volumetric response after uterine artery embolization (UAE). MATERIALS AND METHODS. This retrospective study included 75 patients with 212 uterine leiomyomas who were successfully treated between August 2013 and December 2018. To predict uterine volumetric response, age, number of lesions, and baseline uterine volume were assessed. To predict leiomyoma volumetric response, a multivariate regression analysis was performed to evaluate six predictive factors: location, baseline leiomyoma volume, signal intensity on T1-weighted and T2-weighted MRI, heterogeneity of signal intensity on T2-weighted MRI, and vascularity on subtraction imaging (SI). A five-variable predictive ROC model was developed to evaluate the diagnostic accuracy of the signal intensity ratio on T2-weighted MRI, enhancement ratio, heterogeneity ratio on T2-weighted MRI, location, and baseline leiomyoma volume in predicting at least 40% leiomyoma volumetric response. RESULTS. Age, number of leiomyomas, and baseline uterine volume were not predictive of uterine volumetric response. A submucosal location was the best predictive factor of leiomyoma volumetric response, and it showed 32.2% more leiomyoma volumetric response compared with a nonsubmucosal location (p < .001). Hyperintensity on T2-weighted MRI was the second best predictive factor of leiomyoma volumetric response, and it showed 16.9% more volumetric response compared with hypointense leiomyomas (p = .013). A small baseline leiomyoma volume (< 58 cm³) was associated with 10.2% more leiomyoma volumetric response compared with larger leiomyomas (p = .01). Leiomyomas that were hyperintense on SI showed 7.9% more leiomyoma volumetric response compared with those that were hypointense (p = .014). The five-variable ROC model showed high diagnostic accuracy with an AUC of 0.85, sensitivity of 82%, and specificity of 71%. CONCLUSION. A submucosal location, hyperintensity on T2-weighted MRI, small baseline leiomyoma volume (< 58 cm³), and hyperintense leiomyoma on subtraction imaging are the main independent favorable predictors of leiomyoma volumetric response after UAE. An accurate predictive ROC model was developed that may help in selecting patients suitable for UAE. Quantitative assessment of heterogeneity on T2-weighted MRI showed promising results as a predictor of volumetric response, and further research in this area using texture analysis and radiomics is suggested.

A tissue preparation to characterize uterine fibroid tissue properties for thermal therapies

PURPOSE

Treating uterine fibroids with less invasive therapies such as magnetic resonance-guided focused ultrasound (MRgFUS) is an attractive alternative to surgery. Treatment planning can improve MRgFUS procedures and reduce treatment times, but the tissue properties that currently inform treatment planning tools are not adequate. This study aims to develop an ex vivo uterine fibroid model that can emulate the in vivo environment allowing for characterization of the uterus and fibroid MR, acoustic, and thermal tissue properties while maintaining viability for the necessary postsurgical histopathological assessments.

METHODS

Women undergoing a hysterectomy due to fibroid-related symptoms were invited to undergo a preoperative pelvic MRI and to permit postoperative testing of their uterine specimen. Patients that declined or could not be scheduled for a pre-operative MRI were still able to allow post-operative testing of their excised tissue. Following surgical removal of the uterus, nonmorcellated tissues were reperfused with a Krebs-Henseleit buffer solution. An MR-compatible perfusion system was designed to maintain tissue viability inside the MR suite during scanning. MR imaging protocols utilized preoperatively were repeated on whole sample, reperfused ex vivo uterus specimens. Thermal properties including thermal diffusivity and thermal conductivity of the uterus and fibroids were determined using an invasive needle sensor device in 50% of the specimens. Acoustic property measurements (density, speed of sound and attenuation) were obtained for approximately 20% of the tissue samples using both through-transmission and radiation force balance techniques. Differences between fibroid and uterus and in vivo and ex vivo measurements were evaluated with a two-tailed Student t test.

RESULTS

Fourteen patients participated in the study and measurements were obtained from 22 unique fibroids. Of the 16 fibroids available for preoperative MRI testing, 69% demonstrated classic hypo-intensity relative to the myometrium, with the remainder presenting with iso- (25%) or hyper-intensity (6%). While thermal diffusivity was not significantly different between fibroid and myometrium tissues (0.217 ± 0.047 and 0.204 ± 0.039 mm² /s, respectively), the acoustic attenuation in fibroid tissue was significantly higher than myometrium (0.092 ± 0.021 and 0.052 ± 0.023 Np/cm/MHz, respectively). When comparing in vivo with ex vivo MRI T1 and T2 measurements in fibroids and myometrium tissue, the only difference was found in the fibroid T2 property (P < 0.05). Finally, the developed perfusion protocol successfully maintained tissue viability in ex vivo tissues as evaluated through histological analysis.

CONCLUSIONS

This study developed an MR-compatible extracorporeal perfusion technique that effectively maintains tissue viability, allowing for the direct measurement of patient-specific MR, thermal, and acoustic property values for both fibroid and myometrium tissues. These measured tissue property values will enable further development and validation of treatment planning models that can be utilized during MRgFUS uterine fibroid treatments.

MR-guided Focused Ultrasound for Uterine Fibroids: A Preliminary Study of Relationship between the Treatment Outcomes and Factors of MR Images Including Elastography

We evaluated the value of magnetic resonance elastography (MRE) for the prediction of response to magnetic resonance-guided focused ultrasound (MRgFUS) for uterine fibroids. Eleven patients were enrolled. A fractional change of >30% in Symptoms Severity Score (SSS) was defined as a ‘substantial symptomatic improvement’ at 12 months after treatment. The fractional stiffness value reduction in the patients with a substantial improvement in SSS was significantly higher than that in those without (P = 0.0446).

The predictive value of quantitative DCE metrics for immediate therapeutic response of high-intensity focused ultrasound ablation (HIFU) of symptomatic uterine fibroids

PURPOSE

The aim of this study was to investigate the value of quantitative DCE-MRI parameters for predicting the immediate non-perfused volume ratio (NPVR) of HIFU therapy in the treatment of symptomatic uterine fibroids.

MATERIALS AND METHODS

A total of 78 symptomatic uterine fibroids in 65 female patients were treated with US-HIFU therapy. All patients underwent conventional MRI and DCE-MRI scans 1 day before and 3 days after HIFU treatment. Permeability parameters K ^trans, K _ep, V _e, and V _p and T1 perfusion parameters BF and BV of pretreatment were measured as a baseline, while NPVR was used to assess immediate ablation efficiency. Data were assigned to NPVR ≧ 70% and NPVR < 70% groups. Then, the predictive performances of different parameters for ablation efficacy were studied to seek the optimal cut-off value, and the length of time to calculate the variable parameters in each case was recorded.

RESULTS

(1) It was observed that the pretreatment K ^trans, K _ep, V _e, and BF values of the NPVR ≧ 70% group were significantly lower compared to the NPVR < 70% group (p < 0.05). (2) The immediate NPVR was negatively correlated with the K ^trans, BF, and BV values before HIFU treatment (r = - 0.561, - 0.712, and - 0.528, respectively, p < 0.05 for all). (3) The AUCs of pretreatment K ^trans, BF, BV values, and K ^trans combined with BF used to predict the immediate NPVR were 0.810, 0.909, 0.795, and 0.922, respectively (p < 0.05 for all). (4) The mean time to calculate the variable parameters in each case was 7.5 min.

CONCLUSION

Higher K ^trans, BF, and BV values at baseline DCE-MRI suggested a poor ablation efficacy of HIFU therapy for symptomatic uterine fibroids, while the pretreatment DCE-MRI parameters could be useful biomarkers for predicting the ablation efficacy in select cases. The software used to calculate DCE-MRI parameters was simpler, quicker, and easier to incorporate into clinical practice.

Development of a Model for the Prediction of Treatment Response of Uterine Leiomyomas after Uterine Artery Embolization

Background: Uterine artery embolization (UAE) is one of the minimally-invasive alternatives to hysterectomy for treatment of uterine leiomyomas. There are various factors affecting the outcomes of UAE, but these have only been sporadically studied. Study Objective: To identify factors associated with the efficacy of UAE for the treatment of uterine leiomyoma, and to develop a model for the prediction of treatment response of uterine leiomyomas to UAE. Study design: A retrospective cohort study (Canadian Task Force Classification II-2) Patients: One hundred ninety-eight patients with symptomatic uterine leiomyomas. Intervention: UAE Measurements and Main Results: Among 198 leiomyoma patients who were treated with UAE, 104 who underwent pelvic magnetic resonance imaging (MRI) with diffusion-weighted imaging were selected for developing prediction model. Variables that were statistically significant from the univariate analysis were: location of leiomyoma, total number of lesions, sum of leiomyomas diameters, T2 signal intensity of largest leiomyoma, and T2 leiomyoma:muscle ratio. After a logistic regression analysis, leiomyoma location and T2 signal intensity of the largest leiomyoma were found to be statistically significant variables. Using intramural myomas defined as controls, submucosal leiomyomas showed a greater response to UAE with an odds ratio of 7.6904. The odds ratio of T2 signal intensity with an increase in signal intensity of 10 was 1.093. Using these two variables, we developed a prediction model. The AUC in the prediction model was 0.833, and the AUC in the validation set was 0.791. Conclusion: We identified that submucosal leiomyomas and those leiomyomas that show high signal intensity on T2-weighted imaging will exhibit a greater response to UAE. Prediction models are clinically helpful in selecting UAE as an appropriate treatment option for managing uterine leiomyoma.

Establishment of a scoring system for predicting the difficulty level of high-intensity focussed ultrasound ablation of uterine fibroids

PURPOSE

To establish a scoring system that predicts the difficulty level of high-intensity focussed ultrasound (HIFU) ablation of uterine fibroids.

MATERIALS AND METHODS

Four hundred and twenty-two patients with fibroids were enrolled. The energy efficiency factor (EEF) and sonication time were set as dependent variables, with factors possibly affecting EEF and sonication time including age, body mass index (BMI), the volume of fibroids, the location of the uterus, the type of fibroids, the signal intensity on the T2-weighted imaging (T2WI), the enhancement type, the thickness of the rectus abdominis and the subcutaneous fat layer, the distance from the anterior/posterior surface of the fibroid to the skin, and the abdominal wall scars were set as predictors for building optimal scaling regression models.

RESULTS

The volume of the fibroids, the location of the uterus, the signal intensity on T2WI, enhancement type, rectus abdominis thickness, subcutaneous fat thickness, and distance from the anterior surface of fibroid to the skin were related to EEF. Signal intensity on T2WI, the volume of fibroids, distance from the posterior surface of fibroid to the skin, and enhancement type were related to sonication time. Models that can predict the difficulty level of HIFU for fibroids have been established: for EEF, y ' = 0.338X '₁ - 0.231X '₂+0.156X '₃+0.167X '₄ ; for sonication time, y = 0.227X₁+0.321X₂+0.157X₃+0.194X₄.

CONCLUSIONS

A scoring system for predicting the difficulty level of HIFU treatment for uterine fibroids has been established and it can be used to help select patients and to predict the sonication time for a given fibroid.

Clinical application of high-intensity focused ultrasound ablation for uterine fibroids

HIFU (high-intensity focused ultrasound) ablation is an emerging therapeutic modality that induces thermal coagulative necrosis of biological tissues by focusing high-energy ultrasound waves onto one small spot. This technique is at various stages of clinical applications in several organs. However, it has increasingly been used in the treatment of symptomatic uterine fibroids, a common condition affecting women. Since its first clinical use for symptomatic uterine fibroids, this technique has been recognized for safety, satisfactory therapeutic efficacy in symptom control, uterus-preserving ability, radiation-free nature, and because of the fact that it does not require hospitalization. Owing to its numerous benefits, HIFU ablation is currently one of the major therapeutic options for symptomatic uterine fibroids. In this review, several aspects ranging from the physical principle of HIFU to the long-term outcomes are summarized from the perspective of the clinical application for uterine fibroids.

A comparison of ultrasound-guided high intensity focused ultrasound for the treatment of uterine fibroids in patients with an anteverted uterus and a retroverted uterus

OBJECTIVE

The aim of this study was to compare the treatment outcomes of ultrasound-guided high-intensity focused ultrasound (USgHIFU) for uterine fibroids in patients with an anteverted uterus versus a retroverted uterus.

MATERIALS AND METHODS

Based on the principles of statistics we enrolled 221patients with an anteverted uterus and 221 with a retroverted uterus. All patients had a solitary uterine fibroid and every fibroid was identified as hypointense on the T2 weighted images (T2WI) on magnetic resonance. The baseline characteristics of the patients, treatment results and adverse events were compared between the two groups.

RESULTS

There were no significant differences in baseline characteristics between the two groups. The average non-perfused volume ratio of fibroids was 85.2 ± 18.7% in the group of patients with a retroverted uterus, while it was 87.7 ± 11.8% in patients with an anteverted uterus (P < 0.05). The fibroids in patients with a retroverted uterus were treated using lower sonication power and longer sonication time. During the procedure patients with a retroverted uterus had a higher incidence of sciatic/buttock pain and groin pain, while patients with an anteverted uterus complained of lower abdominal pain or a burning sensation on the skin. Immediately after USgHIFU, the rates of sciatic/buttock pain and skin burn were significantly higher in patients with a retroverted uterus.

CONCLUSION

The results of this study indicated that uterine fibroids with hypointensity on T2WI in a retroverted uterus can be safely and effectively treated with USgHIFU. However, the fibroids in an anteverted uterus are easier to treat with USgHIFU.

Dynamic contrast-enhanced MRI serves as a predictor of HIFU treatment outcome for uterine fibroids with hyperintensity in T2-weighted images

The aim of the present study was to investigate the efficacy of dynamic contrast-enhanced magnetic resonance imaging (MRI) in predicting the outcome of using ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation for the treatment of uterine fibroids with T2 hyperintensity under MRI. A total of 131 uterine fibroids from 131 patients that appeared hyperintense under T2-weighted MRI were analyzed. The uterine fibroids were subjectively categorized into slight, irregular or regular enhancement groups, according to pretreatment dynamic contrast-enhanced MRI in the arterial phase within 60 sec after the injection of gadolinium. The non-perfused volume (NPV), which is indicative of successful ablation, was represented as the non-perfused area inside the uterine fibroids on enhanced MRI scans following treatment. Additionally, the treatment duration, treatment efficiency, sonication duration, energy efficiency ratio and any adverse events were recorded. The results indicated that the average NPV ratio for all the treated fibroids was 68.5%, while the average NPV ratios for fibroids with slight, irregular or regular enhancement were 84.7, 70.6 and 57.1%, respectively. Fibroids with regular enhancement were associated with the lowest NPV ratio and the lowest treatment efficiency, but exhibited the highest energy effect ratio and an elevated risk of severe adverse effects. The results of the present study indicate that hyperintense uterine fibroids with slight and irregular enhancement in the arterial phase of dynamic contrast-enhanced MRI are suitable for USgHIFU treatment. By contrast, uterine fibroids with regular enhancement were associated with the lowest treatment efficacy and safety.

Using microbubble sonographic contrast agent to enhance the effect of high intensity focused ultrasound for the treatment of uterine fibroids

OBJECTIVE

To evaluate the effects of the ultrasound contrast agent SonoVue in enhancing the ablative effects of Ultrasound-Guided high-intensity focused ultrasound (HIFU) on different sub-types of uterine fibroids.

MATERIALS AND METHODS

In this study, 390 fibroids from 319 patients were retrospectively evaluated, among which 155 were treated with SonoVue and 235 were without SonoVue during HIFU ablation. The efficacy of HIFU was evaluated using magnetic resonance scanning (MRI) in all patients.

RESULTS

The total ablation time to achieve the same non-perfused volume was significantly shortened with SonoVue. The average energy used and the acoustic energy for treating 1 mm(3) (EEF) was less when SonoVue is used as enhancing agent. The non-perfused volume (NPV) was measured by post-HIFU MRI and the mean fractional ablation was calculated. Mean NPV was 74% (range: 15%-100%) in the HIFU-only group and 75% (range: 17%-100%) in the HIFU+ SonoVue group. However, for T2 MRI low intensity signal fibroids, NPV in the SonoVue group reached 83% (range: 20%-100%) that was significantly higher than in the HIFU-only group, which was 76% (range: 15%-100%). No differences in adverse events were observed between the two groups.

CONCLUSIONS

Our observations demonstrate that the use of therapeutic SonoVue during the HIFU procedure can significantly decrease the ablation time and the energy requirement for the treatment of the same fibroid volume in all types of fibroids.

Factors influencing the dosimetry for high-intensity focused ultrasound ablation of uterine fibroids: a retrospective study

The aim of this article is to analyze factors affecting sonication dose and build a dosimetry model of high-intensity focused ultrasound (HIFU) ablation for uterine fibroids. Four hundred and three patients with symptomatic uterine fibroids who underwent HIFU were retrospectively analyzed. The energy efficiency factor (EEF) was set as dependent variable, and the factors possibly affecting sonication dose included age, body mass index, size of uterine fibroid, abdominal wall thickness, the distance from uterine fibroid dorsal side to sacrum, the distance from uterine fibroid ventral side to skin, location of uterus, location of uterine fibroids, type of uterine fibroids, abdominal wall scar, signal intensity on T2-weighted imaging (T2WI), and enhancement type on T1-weighted imaging (T1WI) were set as predictors to build a multiple regression model. The size of uterine fibroid, distance from fibroid ventral side to skin, location of uterus, location of uterine fibroids, type of uterine fibroids, signal intensity on T2WI, and enhancement type on T1WI had a linear correlation with EEF. The distance from fibroid ventral side to skin, enhancement type on T1WI, size of uterine fibroid, and signal intensity on T2WI were eventually incorporated into the dosimetry model. The distance from fibroid ventral side to skin, enhancement type on T1WI, size of uterine fibroid, and signal intensity on T2WI can be used as dosimetric predictors for HIFU for uterine fibroids.

Predictive factors for pelvic magnetic resonance in response to arterial embolization of a uterine leiomyoma

OBJECTIVE

Minimally invasive methods are used as alternatives to treat leiomyomas and include uterine artery embolization, which has emerged as a safe, effective method. This study aims to evaluate the magnetic resonance imaging predictors for a reduction in leiomyoma volume in patients undergoing uterine artery embolization.

METHODS

This prospective longitudinal study was performed at a university hospital. We followed 50 symptomatic premenopausal women with uterine leiomyomas who underwent uterine artery embolization. We examined 179 leiomyomas among these patients. Magnetic resonance imaging was performed one month before and six months after uterine artery embolization. Two radiologists who specialized in abdominal imaging independently interpreted the images.

MAIN OUTCOME MEASURES

The magnetic resonance imaging parameters were the uterus and leiomyomas volumes, their localizations, contrast perfusion pattern and node-to-muscle ratio.

RESULTS

Six months after treatment, the average uterine volume reduction was 38.91%, and the leiomyomas were reduced by 55.23%. When the leiomyomas were submucosal and/or had a higher node-to-muscle ratio in the T2 images, the volume reduction was even greater (greater than 50%). Other parameters showed no association.

CONCLUSIONS

We conclude that symptomatic uterine leiomyomas in patients undergoing uterine artery embolization exhibit volume reductions greater than 50% by magnetic resonance imaging when the leiomyomas are submucosal and/or had a high node-to-muscle ratio in the T2 images.

Feasibility of ultrasound-guided high intensity focused ultrasound ablating uterine fibroids with hyperintense on T2-weighted MR imaging

PURPOSE

To retrospectively investigate whether uterine fibroids with hyperintense on pretreatment T2-weighted magnetic resonance imaging (MRI) could be treated with ultrasound-guided high intensity focused ultrasound (USgHIFU).

MATERIALS AND METHODS

282 patients with 282 symptomatic uterine fibroids who underwent USgHIFU treatment were retrospectively analyzed. Based on the signal intensity of T2-weighted MRI, uterine fibroids were classified as hypointense, isointense and hyperintense. Hyperintense fibroids were subjectively further subdivided into heterogeneous hyperintense, slightly homogeneous hyperintense and markedly homogeneous hyperintense based on the signal intensity of fibroid relative to myometrium and endometrium on T2-weighted MRI. Enhanced MRI was performed within one month after HIFU treatment. Non-perfused volume (NPV, indicative of successful ablation) ratio, treatment time, treatment efficiency, energy effect ratio and adverse events were recorded.

RESULTS

The median volume of uterine fibroids was 70.3 cm(3) (interquartile range, 41.1-132.5 cm(3)). The average NPV ratio, defined as non-perfused volume divided by the fibroid volume after HIFU treatment, was 76.8 ± 19.0% (range, 0-100%) in the 282 patients. It was 86.3 ± 11.9% (range, 40.9-100.0%) in the group with hypointense fibroids, 77.1 ± 16.5% (range, 32.2-100.0%) in isointense fibroids, and 67.6 ± 23.9% (range, 0-100.0%) in hyperintense fibroids. The lowest NPV ratio, lowest treatment efficiency, more treatment time, more sonication energy and pain scores were observed in the slightly homogeneous hyperintense fibroids, and the NPV ratio was 55.8 ± 26.7% (range, 0-83.9%) in this subgroup.

CONCLUSION

Based on our results, the heterogeneous and markedly homogeneous hyperintense fibroids were suitable for USgHIFU, and only the slightly homogeneous hyperintense fibroids should be excluded.

Uterine artery embolization for symptomatic fibroids with high signal intensity on T2-weighted MR imaging

Objective

To evaluate the effectiveness of uterine artery embolization (UAE) for treating symptomatic fibroids with high signal intensity (SI) on magnetic resonance (MR) T2-weighted imaging (T2WI).

Materials and Methods

A total of 537 cases, consisting of 14 patients with high SI fibroids on T2WI (T2 high group), were retrospectively included and compared with 28 randomly selected patients with low SI fibroids on T2WI (control group). High SI of a predominant fibroid on T2WI was defined as having the same or higher SI than the myometrium. Patient ages ranged from 28 to 52 years (mean, 38.1 years). All patients underwent MRI before and after UAE. Predominant fibroid and uterine volumes were calculated with MR images. Symptom status in terms of menorrhagia and dysmenorrhea was scored on a scale of 0-10, with 0 being no symptoms and 10 being the baseline, or initial symptoms.

Results

Of the patients in the T2 high group, 13 out of 14 (92.9%) patients demonstrated complete necrosis of the predominant fibroids. The mean volume reduction rates of the predominant fibroids in the T2 high group was 61.7% at three months after UAE, which was significantly higher than the volume reduction rates of 42.1% noted in the control group (p < 0.05). Changes in symptom scores for menorrhagia and dysmenorrhea after UAE (baseline score minus follow-up score) were 4.9 and 7.5 in T2 high group and they were 5.0 and 7.7 in control group, suggesting a significant resolution of symptoms (p < 0.01) in both groups but no significant difference between the two groups.

Conclusion

UAE is effective for uttering fibroids showing high SI on T2WI. The mean volume reduction rate of the predominant fibroids three months after UAE was greater in the T2 high group than in the control group.

Volumetric MR-HIFU ablation of uterine fibroids: role of treatment cell size in the improvement of energy efficiency

PURPOSE

To evaluate the energy efficiency of differently sized volumetric ablations in MR-guided high-intensity focused ultrasound (MR-HIFU) treatment of uterine fibroids.

MATERIALS AND METHODS

This study was approved by the institutional review board and informed consent was obtained from all participants. Ten symptomatic uterine fibroids (mean diameter 8.9 cm) in 10 women (mean age 42.2) were treated by volumetric MR-HIFU ablation under binary feedback control. The energy efficiency (mm3/J) of each sonication was calculated as the volume of lethal thermal dose (240 equivalent minutes at 43 °C) per unit acoustic energy applied. Operator-controllable parameters and signal intensity ratio of uterine fibroid to skeletal muscle on T2-weighted MR images were tested with univariate and multivariate analyses to discern which parameters significantly correlated with the ablation energy efficiency.

RESULTS

We analyzed a total of 236 sonications. The energy efficiency of the ablations was 0.42±0.25 mm3/J (range 0.004-1.18) with energy efficiency improving with the treatment cell size (4 mm, 0.06±0.06 mm3/J; 8 mm, 0.29±0.12 mm3/J; 12 mm, 0.58±0.18 mm3/J; 16 mm, 0.91±0.17 mm3/J). Treatment cell size (r=0.814, p<0.001), distance of ultrasound propagation (r=-0.151, p=0.020), sonication frequency (1.2 or 1.45 MHz; p<0.001), and signal intensity ratio (r=-0.205, p=0.002) proved to be significant by univariate analysis, while multivariate analysis revealed treatment cell size (B=0.075, p<0.001), US propagation distance (B=-6.928, p<0.001), and signal intensity ratio (B=-0.024, p=0.001) to be independently significant.

CONCLUSION

Energy efficiency in volumetric MR-HIFU ablation of uterine fibroids improves with increased treatment cell size, independent of other significant contributors such as distance of ultrasound propagation or signal intensity of the tumor on T2-weighted MR imaging.

Differential efficacy of gonadotropin-releasing hormone (GnRH) agonist treatment on pedunculated and degenerated myomas: a retrospective study of 630 women

This study was designed to compare the anatomical location of myomas (submucous, intramural, subserous, or cervical), whether pedunculated or non-pedunculated if degenerated or undegenerated and relating these findings to myoma volume reduction in women treated with gonadotropin-releasing hormone agonist (GnRHa). Our retrospective study group included 630 patients with symptoms attributed to fibroids. They were treated with a single GnRH agonist for 20 weeks and the size of the myoma was monitored by magnetic resonance imaging and/or ultrasonographic scan. During a 20 week-treatment, submucous, intramural, or subserous fibroids showed an overall reduction of 63% (P<0.01) with little variation between these types. No reduction in size was seen in cases of pedunculated, degenerated, or cervical myomas. These data suggest that GnRH agonist therapy might be used primarily for non-pedunculated and undegenerated myomas.

Semiquantitative assessment of MR imaging in prediction of efficacy of gonadotropin-releasing hormone agonist for volume reduction of uterine leiomyoma: initial experience

PURPOSE

To prospectively determine if semiquantitative assessment of R2* images and T1-weighted magnetic resonance (MR) images of leiomyomas correlates with the efficacy of gonadotropin-releasing hormone (GnRH) agonist treatment for volume reduction.

MATERIALS AND METHODS

Internal review board approval and informed consent were obtained for this study. Twenty women (mean age, 36.3 years) with intramyometrial leiomyomas were enrolled in this study. Single-section double-echo dynamic MR imaging was performed before GnRH agonist administration. T2-weighted images were obtained before and after two or three GnRH agonist injections (1.88 mg leuprorelin acetate). The steepest signal intensity (SI) upslope on T1-weighted images and the area under the curve (AUC) on R2* images were determined by using a 16 x 16-voxel matrix that was placed in the center of a leiomyoma. Pearson correlation analysis was performed to compare the percentage of volume reduction with SI upslope and AUC. Unpaired t test was performed to evaluate the difference between leiomyomas with AUC and SI upslope values that were less than or greater than the mean.

RESULTS

Percentage of volume reduction ranged from 6.2% to 51.1%. The mean AUC and mean SI upslope were 39.2 and 9.83% per second, respectively. There was a significant correlation between the AUC and the percentage of volume reduction (r = 0.81, P < .001), although no significant correlation was observed between the SI upslope and the percentage of volume reduction. A significant difference in percentage of volume reduction was observed in leiomyomas by using mean AUC as a cutoff value (P = .003).

CONCLUSION

AUC on R2* images correlates with the efficacy of GnRH agonist before initiation of treatment for volume reduction of leiomyoma.

Uterine leiomyomas: MR imaging-guided focused ultrasound surgery--imaging predictors of success

PURPOSE

To retrospectively assess the magnetic resonance (MR) imaging predictors of success at reducing uterine leiomyoma volume and achieving patient symptom relief 12 months after MR imaging-guided focused ultrasound surgery.

MATERIALS AND METHODS

This single-center retrospective analysis of 71 symptomatic fibroids in 66 women was approved by the institutional review board and was HIPAA-compliant. Patients were treated with MR imaging-guided focused ultrasound surgery. The volume of treated fibroid and nonperfused volume (NPV) were calculated with software, while symptom outcome was assessed with a symptom severity score (SSS). Fibroids were classified as hyperintense or hypointense relative to skeletal muscle on pretreatment T2-weighted MR images.

RESULTS

Baseline volume of treated fibroids was 255.5 cm(3) +/- 201.7 (standard deviation), and baseline SSS was 61.5 +/- 14.9. Both pretreatment fibroid signal intensity (SI) and posttreatment NPV predicted 12-month volume reduction independently: Fibroids with an NPV of at least 20% or with low SI both showed significantly larger volume reduction (17.0% +/- 13.0 and 17.2% +/- 20.1, respectively) than fibroids with an NPV less than 20% or with high SI (10.7% +/- 18.2 and no significant change, respectively). Patients whose fibroids demonstrated an NPV of at least 20% also experienced a larger decrease in SSS than did patients with fibroids with an NPV less than 20% (50.1% +/- 19.8 vs 32.6% +/- 29.9).

CONCLUSION

Fibroids with low SI on pretreatment T2-weighted MR images were more likely to shrink than were ones with high SI. The larger the NPV immediately after treatment, the greater the volume reduction and symptom relief were. These findings may help both in selecting appropriate patients for MR-guided focused ultrasound surgery and in predicting patient outcome.

Mid-term outcome of magnetic resonance-guided focused ultrasound surgery for uterine myomas: from six to twelve months after volume reduction

STUDY OBJECTIVE

To clarify the volume change ratio of uterine myomas treated with magnetic resonance-guided focused ultrasound surgery (MRgFUS), in relation to the signal intensity of T(2)-weighted magnetic resonance (MR) images.

DESIGN

Prospective study (Canadian Task Force classification II-3).

SETTING

Department of Gynecology, Shinsuma General Hospital, Kobe, Japan.

PATIENTS

Forty-eight myomas in 35 patients were followed up with MR images 6 months after MRgFUS, and 23 myomas in 17 patients were followed up 12 months after MRgFUS. Before treatment, the myomas were classified into 3 types on the basis of the signal intensity of T(2)-weighted MR images as follows: Type 1, low intensity; type 2, intermediate intensity; type 3, high intensity.

INTERVENTIONS

Thermal ablation therapy was performed with an MRgFUS system (ExAblate 2000).

MEASUREMENTS AND MAIN RESULTS

MRgFUS produced a greater volume reduction in type 1 and type 2 myomas than in type 3 myomas. Nonperfused areas always diminished in the period after MRgFUS; however, the volume change was affected by the volume change ratio of perfused areas inside the treated myomas.

CONCLUSION

At present, type 3 myomas should be exempted from the application of MRgFUS, because the nonperfused ratio immediately after the procedure was small compared with that in type 1 and type 2 myomas, and the subsequent volume change was unfavorable.

Magnetic resonance-guided focused ultrasound surgery for uterine fibroids: relationship between the therapeutic effects and signal intensity of preexisting T2-weighted magnetic resonance images

OBJECTIVE

This study was undertaken to clarify the relationship between the signal intensity of T2-weighted magnetic resonance images and the therapeutic effect of magnetic resonance-guided focused ultrasound surgery (MRgFUS) on uterine fibroids.

STUDY DESIGN

Ninety-five fibroids in 63 patients were classified into 3 types based on the signal intensity of T2-weighted magnetic resonance images as follows: type 1, low intensity; type 2, intermediate intensity; type 3, high intensity. The treated area ratio of MRgFUS and the volume reduction ratio 6 months after treatment were used as the indices of therapeutic effect.

RESULTS

The treated area ratio of type 3 fibroids was the lowest among the 3 types (P < .01). The volume reduction ratio correlated with the treated area ratio (r = 0.64; P < .01).

CONCLUSION

The efficacy of MRgFUS correlates with the signal intensity of T2-weighted magnetic resonance images. Type 1 and type 2 fibroids are suitable candidates for MRgFUS, whereas type 3 fibroids are not.

Predictive value of magnetic resonance imaging signal and contrast-enhancement characteristics on post-embolization volume reduction of uterine fibroids

PURPOSE

To assess the magnetic resonance imaging (MRI) signal and contrast-enhancement features of uterine fibroids before and after embolization, and to determine whether or not there are pre-embolization MRI characteristics that predict the volume reduction of fibroids.

MATERIAL AND METHODS

Uterine fibroid embolization (UFE) was carried out in 28 fibroids of 20 patients, all of whom were symptomatic. The patients were prospectively evaluated with T1-weighted, T2-weighted, and gadolinium-enhanced T1 MRI sequences before and 6 months after embolization. The relationship between the characteristics of MRI signal and contrast-enhancement features of fibroids before the procedure and the change in size of the lesions after treatment was investigated.

RESULTS

Before embolization, the mean volume of fibroids was 123 cm3 (8-560 cm3). The decrease rate in fibroid volumes was 44.6% (range 7-70%) 6 months after embolization. Volume reduction was more prominent in fibroids that had a high signal intensity on T2-weighted images and a marked contrast enhancement on T1-weighted images (P < 0.001). However, the volume reduction was insufficient in fibroids with high signal characteristics on pre-contrast T1-weighted images (P < 0.001).

CONCLUSION

MRI is an effective method for revealing size and signal changes of fibroids after embolization. MRI signal characteristics and the contrast-enhancement pattern of fibroids before embolization can predict tumor volume reduction after embolization.

Leiomyoma of the ovary presenting with Meigs' syndrome

Ovarian leiomyoma is a rare tumor. Ovarian leiomyoma accompanied with Meigs' syndrome is extremely rare. We report a case of ovarian leiomyoma presenting with Meigs' syndrome, which was first noted as dyspnea in a 79-year-old woman. A whole-body examination revealed a solid mass of the ovary, accumulation of ascites and pleural effusion, and elevated serum carbohydrate antigen 125. Abdominal hysterectomy and salpingo-oophorectomy were carried out. After the surgery, ascites and pleural effusion disappeared. The pathological diagnosis of the removed tumor was leiomyoma of the left ovary. The patient has been healthy for 24 months after the surgery, with no signs of recurrence. We also review the literature on this disease and the clinicopathologic characteristics of the current case are discussed.

MR imaging of the uterine cervix: imaging-pathologic correlation

Magnetic resonance (MR) imaging is useful not only for preoperative staging of gynecologic malignancies but also for prediction of the histopathologic features of a variety of intrapelvic tumors. Familiarity with the specific imaging findings that have been reported for the uterine cervix is a goal of radiologists. The typical MR imaging findings of uterine cervical lesions correspond to the histopathologic features. These lesions can be categorized as epithelial neoplasms, nonepithelial neoplasms, and nonneoplastic diseases. Cervical carcinoma accounts for most cases of malignant lesions and is staged by using the classification system established by the International Federation of Gynecology and Obstetrics. MR imaging allows differentiation between endophytic and exophytic growth and between normal and abnormal findings after hysterectomy and irradiation. Other epithelial neoplasms of the uterine cervix include adenoma malignum, which is a special type of cervical adenocarcinoma, as well as carcinoid tumor and malignant melanoma. Nonepithelial neoplasms of the uterine cervix include malignant lymphoma and leiomyoma. Nonneoplastic diseases of the uterine cervix include cervical pregnancy, cervicitis, nabothian cysts, polyps, and endometriosis.

Value of magnetic resonance imaging in predicting efficacy of GnRH analogue treatment for uterine leiomyoma

BACKGROUND

Estimating pharmacological efficacy is important when selecting conservative treatment of uterine leiomyoma. Hence, the ability of magnetic resonance (MR) imaging to predict gonadotrophin-releasing hormone (GnRH) analogue efficacy was investigated.

METHODS

A total of 85 lesions was studied in 40 patients who were clinically diagnosed as having uterine leiomyoma and treated with GnRH analogue for 24 weeks. To evaluate changes in lesion size, T2-weighted and gadopentetate-dimeglumine (Gd-DTPA)-enhanced, T1-weighted MR images were obtained within 2 weeks before, and immediately after termination of, GnRH analogue treatment.

RESULTS

An average 46.3% size reduction was observed in 45 lesions (52.9%); these were seen as low signal intensity on T2-weighted images and enhanced by Gd-DTPA. Also, an average 44.7% size reduction was observed in lesions enhanced by Gd-DTPA, irrespective of signal intensity findings on T2-weighted images. The average size reduction of unenhanced lesions was only 17.8%, and significantly different from enhanced lesions (P < 0.001). The prediction of efficacy was difficult in those lesions not enhanced.

CONCLUSIONS

It is considered that evaluation of MR signal intensities, and the presence or absence of Gd-DTPA enhancement, would predict treatment efficacy before GnRH analogue administration.

Uterine fibroid embolization: assessment of treatment response using perfusion-weighted extraslice spin tagging (EST) magnetic resonance imaging

In this pilot study, we demonstrate the feasibility of using an arterial spin tagging technique, Extraslice Spin Tagging (EST), to assess tumor perfusion before and after uterine fibroid embolization (UFE) and correlate the changes in perfusion with fibroid size reduction. We followed two patient volunteers over a six-month period. The perfusion-weighted image intensity decreased immediately after UFE. The size of the tumor decreased by 14% immediately after UFE and continued to decrease over a six-month period to 84%. The imaging methods presented allow for rapid measurement of tumor volume and the evaluation of perfusion of the tumor without the need for intravenous administration of gadolinium compounds. J. Magn. Reson. Imaging 2001;13:982-986.

Uterine fibroleiomyoma: MR imaging appearances before and after embolization of uterine arteries

PURPOSE

To evaluate the magnetic resonance (MR) imaging appearances of uterine fibroleiomyoma before and after embolization and to determine whether there are preembolization MR imaging characteristics that are predictive of a successful outcome.

MATERIALS AND METHODS

MR imaging was performed in 18 patients (32 fibroleiomyomas) before and at 2 and 6 months after embolization of the uterine arteries. On each occasion, fibroleiomyoma signal intensity and gadolinium enhancement characteristics were assessed in comparison with those of myometrium on T1-weighted and gadolinium-enhanced images or with those of skeletal muscle on T2-weighted images. Fibroleiomyoma volume was measured by using the ellipsoid formula.

RESULTS

The mean fibroleiomyoma volume before embolization was 340 cm3 (range, 15-1,383 cm3). The mean reduction in fibroleiomyoma volume was 43% at 2 months and 59% at 6 months. Before embolization, high signal intensity on T1-weighted images was predictive of a poor response (P = .008), and high signal intensity on T2-weighted images was predictive of a good response (P = .007). The degree of gadolinium enhancement was not correlated with fibroleiomyoma volume reduction (P = .46).

CONCLUSION

MR imaging was useful for evaluation of changes in fibroleiomyoma volume after uterine arterial embolization. MR imaging characteristics of fibroleiomyomas before embolization can help predict subsequent response to treatment.