Volume 19, Issue 5 , Pages 662-667, May 2008
Clinical Failure after Uterine Artery Embolization: Evaluation of Patient and MR Imaging Characteristics
Article Outline
Purpose
To investigate the patient and magnetic resonance (MR) imaging characteristics associated with clinical failure after uterine artery embolization (UAE).
Materials and Methods
Seventy-eight consecutive patients who underwent UAE were examined. Contrast-enhanced MR imaging was performed before and 4 months after the procedure, and clinical follow-up was performed at 15 months. Patients were divided into success and failure groups strictly on the basis of their clinical outcomes. Clinical follow-up included evaluation of fibroid symptoms and the need for further treatment after UAE. Findings at pre- and postprocedural MR imaging were compared, and data collected included changes in uterine and fibroid volumes, fibroid location, and fibroid perfusion.
Results
Fifty-eight patients were placed into the success group and 20 into the failure group. There were no differences between the baseline characteristics of the two groups. The reduction in uterine and dominant fibroid volumes was greater in the success group compared with the failure group; however, the difference was not statistically significant (success group: [295/845] 34.9% vs [80/282.5] 28.3%, respectively, P = .18; failure group: [317/733] 43.2% vs [114/337.6] 33.9%, P = .32). The reduction in total fibroid volume was greater in the success group than the failure group ([189.6/393.5] 48.2% vs [148.7/439.9] 33.8%, respectively; P = .02) despite the fact that the percentage of fibroids completely infarcted was similar between the two groups ([136/172] 79% vs [41/50] 82%, P = .77). Pedunculated subserosal fibroids were more common in the failure group than in the success group (P < .03) and did not reduce in volume as significantly (53.8% vs 14.7%, respectively; P = .02).
Conclusions
In general, the reduction in total fibroid volume after embolization is smaller in patients with poor clinical improvement. In addition, these patients have a higher number of pedunculated subserosal fibroids, and these fibroids tend to reduce in volume to a lesser extent.
Abbreviation: UAE, uterine artery embolization
UTERINE leiomyomas are the most common benign tumors of the female pelvis, with a prevalence of 20%–25% (1). Symptomatic patients commonly complain of menorrhagia, dysmenorrhea, urinary frequency, and a sensation of a mass around the lower abdomen. In the past decade, uterine artery embolization (UAE) has become a well-accepted standard of care in reducing symptoms from leiomyomas.
Several studies have described the clinical success of this procedure and how it compares with more traditional and invasive treatment modalities such as myomectomy or hysterectomy (2, 3, 4, 5, 6, 7, 8). Although UAE has a very high procedural success rate of close to 100%, the clinical success rate does not correlate to this figure. A recent randomized trial comparing UAE and surgery after 1 year demonstrated a 10% clinical failure rate resulting in repeat intervention, and another trial comparing UAE and hysterectomy after 2 years demonstrated a 23.5% clinical failure rate resulting in repeat intervention (7, 8). Although many reasons have been proposed as the cause of failure, currently, incomplete fibroid infarction seems to be the most widely accepted explanation (9). To date, a limited number of studies have been published analyzing the fibroid features (eg, fibroid location and perfusion) that may affect clinical outcomes. In particular, there is a paucity of data to explain why up to 20%–25% of patients have a suboptimal clinical response despite successful embolization. We undertook this study to analyze the patient and magnetic resonance (MR) imaging fibroid features that may help us understand why some patients had clinically failed UAE.
Materials and Methods
This study was a retrospective analysis of prospectively collected data from a nonrandomized cohort of patients from our centers. The local institutional review board approved the study design.
All patients with symptomatic uterine fibroids treated with UAE between January 2003 and February 2007 were included in this study. Their symptoms included menorrhagia, dysmenorrhea, and/or bulk symptoms such as urinary frequency, nocturia, or a sensation of a mass in the lower abdomen. As part of our multidisciplinary approach, a gynecologist must have assessed all patients before UAE. Each patient must have undergone preprocedural clinical work-up and contrast medium–enhanced MR imaging to assess fibroid characteristics and to exclude other abnormalities that might account for their symptoms. As part of our protocol, contrast-enhanced MR imaging was also performed 4 months after embolization unless there were specific contraindications. Exclusion criteria for this study included the presence of other uterine abnormalities that may account for the symptoms (including uterine malignancy, adenomyosis, or endometriosis) and failure to comply with clinical and radiologic follow-up.
The embolization technique was similar to that used in a previously published series (10). Briefly, UAE was performed with the patient under conscious sedation and local anesthesia. A single common femoral artery access was obtained. Selective catheterization of the uterine arteries was performed by using a uterine catheter (Robert's; Cook, Bloomington, Indiana). A microcatheter was not routinely employed unless the uterine arteries were tortuous and embolization could not be performed safely with the 0.035 inch lumen catheter. The embolic agent used was 350–500-μm polyvinyl alcohol particles (Contour; Boston Scientific, Natick, Massachusetts). The embolization end point was when there was near-complete flow stasis and the presence of contrast medium in the uterine artery for more than 3 seconds after the injection of 2 mL of contrast medium. After the procedure, all patients were admitted overnight for observation and pain medication. Our pain management protocol included intravenous patient-controlled analgesia with additional intravenous analgesia when required. Most patients were discharged the following day unless there was an unexpected complication.
All MR images were obtained with a 1.5-T system (Excite; GE Medical Systems, Milwaukee, Wisconsin). After an initial localization scan was obtained, the following sequences were performed: axial T1-weighted fast spoiled gradient-echo imaging; sagittal T2-weighted fast spin-echo imaging; sagittal dynamic contrast-enhanced T1-weighted fast spoiled gradient-echo imaging at 0, 30, 60, 90 seconds after the administration of a gadolinium chelate; and axial delayed T1-weighted fast spoiled gradient-echo imaging.
At baseline, the following information was collected for each patient: age, presenting symptoms, previous gynecologic procedures, uterine volume, number of fibroids larger than 2 cm, fibroid volume, and fibroid location. Uterine and fibroid characteristics were determined from pre-UAE MR images. Only fibroids greater than 2 cm were included, and the dominant fibroid was defined as the fibroid with the greatest initial volume. Uterine and fibroid volumes were calculated by using the formula for a prolate ellipse, as follows: length × width × depth × 0.5233. Fibroid location was defined according to Goodwin et al (11) and categorized as submucosal, intramural, subserosal, or pedunculated subserosal (center of fibroid outside the uterus attached by a stalk narrower than 50% of the diameter of the fibroid).
Follow-up data collection included analysis of the 4-month postprocedural contrast-enhanced MR image with which uterine volume, fibroid volumes, and fibroid perfusion were obtained. The amount of fibroid perfusion was determined by evaluating the dynamic contrast-enhanced sagittal series and the postcontrast axial images, estimating the volume of fibroid tissue exhibiting contrast enhancement relative to the total volume of the fibroid. This estimation was then categorized into either 0%–10% (infarcted) or more than 10% (uninfarcted). The presence of new fibroids or any other uterine changes were also noted. Two experienced radiologists completed all MR imaging analyses independently (K.T.T. and M.E.S.).
Clinical follow-up included outpatient clinic visits at 3, 6, and 12 months after treatment. A telephone consultation was performed and a questionnaire administered before completion of this study to update the clinical status of the patients. All patients were asked to categorize menorrhagia, dysmenorrhea, mass- and/or heaviness-related discomfort, and urinary frequency as being “completely resolved,” “greatly improved,” “moderately improved,” “no change,” or “worse” after UAE. These symptom ratings were then converted to numeric scores from 1 (“worse”) to 5 (“completely resolved”). After the collection of clinical data, patients were divided into success and failure groups. The success group consisted of patients who reported clinical improvement of their symptoms compared with their pre-UAE status. The inclusion criteria for the failure group included patients who experienced clinical worsening of any symptom compared with their preprocedure status, patients with no improvement of any symptoms, or patients who sought out or received further treatment due to lack of perceived benefit from UAE. This failure categorization is far broader than that used in most studies and is strictly based on clinical outcomes.
All statistical tests were performed with the t test for continuous data, and comparison of categorical data was completed with the χ2 test. All t tests were two-tailed unless otherwise stated, and P values of less than .05 were considered statistically significant. All reported changes were compared to baseline values. Power analysis was not performed.
Results
A total of 107 patients were included in this study. All patients underwent preprocedural MR imaging and UAE. Twenty-two patients were immediately removed from the study because they did not return for postprocedural MR imaging for various reasons, three patients did not receive contrast medium at postprocedural MR imaging, two patients had an additional diagnosis of endometriosis, one patient underwent only unilateral UAE due to anatomic variation and inability to select the left uterine artery, and one patient had a prothrombotic disorder and was excluded to avoid confounding factors contributing to her symptoms. Thus, 78 patients completed clinical follow-up, and all these patients had completed pre- and post-UAE MR imaging.
Of these 78 patients, 58 were classified into the clinical success group and 20 were classified into the clinical failure group. The latter group consisted of eight patients who reported worsening of symptoms, three with no improvement in any of their symptoms, three who actively sought further treatment due to perceived suboptimal symptomatic improvement, and six who underwent further treatment (four had hysterectomy and two had myomectomy). Follow-up MR imaging was performed at an average (±standard deviation) of 3.9 months ± 1.2 after UAE in the success group and 3.8 months ± 1.3 in the failure group (P = .30). Clinical follow-up was performed in all patients in the success and failure groups, with a mean follow-up of 14.9 months ± 5.7 and 14.5 months ± 6.9, respectively (P = .65).
The baseline characteristics of the two groups are shown in Table 1. No significant differences were noted between the patient groups. There were 172 fibroids larger than 2 cm in the success group and 50 in the failure group. Presenting symptoms were very similar for both groups. In both groups, most patients reported menorrhagia as one of their symptoms ([53/58] 91% and [18/20] 90% in the success and failure groups, respectively; P = .86). In both groups, dysmenorrhea and urinary symptoms such as urinary frequency and/or nocturia were reported to a lesser degree than the feeling of a mass or heaviness in the lower abdomen. Most patients had multiple symptoms, with an average of 3.0 and 2.8 symptoms of a maximum of four in the success and failure groups, respectively.
Table 1. Baseline Patient Characteristics
| Characteristic | Success Group (n = 58) | Failure Group (n = 20) | P Value |
|---|---|---|---|
| Mean age (y) | 43.7 ±6.5 | 42.1±4.2 | .31 |
| Uterine volume (cm3) | 845.0±537.7 | 733.0±535.4 | .42 |
| No. of fibroids | 2.97±1.60 | 2.50±1.73 | .28 |
| Dominant fibroid volume (cm3) | 282.5±264.8 | 337.6±381.0 | .48 |
| Total fibroid volume (cm3) | 393.5±319.0 | 439.9±544.9 | .65 |
| No. of patients with symptoms | |||
| Dysmenorrhea | 32 (55) | 13 (65) | .45 |
| Menorrhagia | 53 (91) | 18 (90) | .86 |
| Mass/heaviness | 47 (81) | 15 (75) | .59 |
| Urinary symptoms | 41 (71) | 10 (50) | .12 |
| No. of symptoms | 3.0±1.1 | 2.8±0.9 | .46 |
| No. of patients who underwent previous interventions⁎ | 11 (19) | 2 (10) | .30 |
| No. of patients with ovarian supply to any fibroid | 4 (6.9) | 1 (5) | .75 |
⁎Most patients underwent previous intervention more than 5 years before UAE. |
As discussed earlier, data from clinical follow-up were used to divide the patients into the success and failure groups. Differences in clinical improvement were statistically significant between the two groups for all symptoms (Table 2). All patients in the success group reported improvement in most of the studied symptoms. It is interesting that, with the exception of three patients who did not experience any clinical improvement, patients in the failure group reported improvement in at least one symptom. Dysmenorrhea was noted to improve the least in the failure group as compared to the other measured symptoms, with three patients reporting worsening of dysmenorrhea after UAE.
Table 2. Comparison of MR Imaging Findings after UAE
| Finding | Success Group (n=58) | Failure Group (n=20) | P Value |
|---|---|---|---|
| Clinical follow-up | |||
| Dysmenorrhea | 3.91±.68 | 2.53±1.06 | <.01 |
| Menorrhagia | 4.09±.71 | 2.79±1.18 | <.01 |
| Mass/heaviness | 4.11±.81 | 3.07±1.16 | <.01 |
| Urinary symptoms | 3.93±.88 | 3.09±1.22 | .05 |
| MR imaging follow-up | |||
| Uterine volume (cm3) | 545.3±388.3 | 526.6±418.7 | .86 |
| Reduction in uterine volume (%) | 34.9±17.9 | 28.3±21.1 | .18 |
| Reduction in dominant fibroid volume (%) | 43.2±37.6 | 33.9±29.0 | .32 |
| Reduction in total fibroid volume (%) | 48.2±21.3 | 33.8±30.2 | .02 |
| Infarcted dominant fibroid (%) | 82.8 | 85.0 | .27 |
| Completely infarcted fibroids (%)⁎ | 79.3±30.8 | 81.7±32.7 | .77 |
⁎Mean of percentage of fibroids infarcted in each patient. |
Follow-up MR images were compared between the two groups (Table 2). Not surprisingly, differences were noted. The reduction in uterine volume and dominant fibroid volumes was greater in the success group than in the failure group, although the difference was not statistically significant. There was, however, a statistically significant difference in the reduction of total fibroid volume, with the success and failure groups having 48.2% and 33.8% reductions, respectively (P = .02). Despite the fact that the success group had a greater reduction in fibroid volumes, both groups had very similar infarction rates for dominant and all other fibroids.
Upon further MR imaging analysis, an observation of interest was noted in the pattern of fibroid location between the two groups: There were proportionately more pedunculated subserosal fibroids noted within the failure group (Table 3). Of the 20 patients within the failure group, 15 pedunculated subserosal fibroids were found in nine patients, with seven of these patients having one pedunculated fibroid and the other two patients having multiple pedunculated subserosal fibroids. In the success group, a total of 12 such fibroids were found in nine of the 58 patients. Seven patients had a single pedunculated subserosal fibroid and two patients had multiple pedunculated subserosal fibroids. A pedunculated subserosal fibroid was uninfarcted in five of the nine patients in the failure group compared to three of the nine patients in the success group. Comparison of fibroid size reduction after embolization according to location also revealed differences between the groups (Table 4). Significantly, the pedunculated subserosal fibroids in the failure group did not reduce in volume to the same extent as that in the success group (14.7% vs 53.8%, respectively). There was also a trend of greater fibroid size reduction in the success group for submucosal and intramural fibroids, although it did not achieve a level of statistical significance.
Table 3. Fibroid Location
| Fibroid Location | Success Group (n=58) | Failure Group (n=20) |
|---|---|---|
| Submucosal | 29(50) | 7(35) |
| Intramural | 43(74) | 12(60) |
| Serosal | 25(43) | 5(25) |
| Pedunculated serosal | 9(16) | 9(45) |
Table 4. Percentage Reduction in Fibroid Volume according to Fibroid Location
| Fibroid Location | Success Group (n=58) | Failure Group (n=20) | P Value |
|---|---|---|---|
| Submucosal | 60.6±24.8 | 43.7±56.3 | .19 |
| Intramural | 51.5±25.0 | 39.5±21.0 | .07 |
| Serosal | 38.1±52.7 | 38.2±34.9 | .99 |
| Pedunculated serosal | 53.8±21.8 | 14.7±50.9 | .02 |
None of the 78 patients in our study had a major adverse event after UAE. There were, however, some minor adverse events. In the success group, the following events occurred after UAE: two patients reported fibroid expulsion, two patients reported transient urinary hesitancy, two patients (both older than 50 years) reported permanent amenorrhea, one patient reported transient amenorrhea, one patient developed an acne-type rash that subsequently resolved, and one patient developed a urinary tract infection shortly after the procedure. In the failure group the following events occurred after UAE: two patients reported fibroid expulsion, one patient reported urinary hesitancy and had to visit the hospital on two occasions for acute urinary retention necessitating Foley catheter placement, and one patient reported experiencing occasional numbness in her leg distal to the femoral access site.
Discussion
This study was designed to investigate the patient and imaging characteristics associated with clinical failure after UAE. Several studies have investigated and reported extensively on the reduction in uterine and fibroid volumes and clinical outcomes (3, 4, 5, 6). However, few reports have evaluated the features of patients with clinical failure. We employed a broad definition of failure in this setting and included all patients who did not have improvement in most of their symptoms, those who experienced worsening of any clinical symptom, and those who sought or received further treatment due to perceived suboptimal symptomatic response after UAE. Comparing the two groups, we noted there was greater percentage reduction in uterine and dominant fibroid volumes in the success group (34.9% ± 17.9 vs 28.3% ± 21.1 and 43.2% ± 37.6 vs 33.9% ± 29.0, respectively). Although these figures are not statistically significant, likely due to the small sample size, there is a strong trend to suggest that those patients with suboptimal clinical response tend to have poor uterine and/or fibroid volume reduction. When total fibroid volume reduction was considered, however, a significant difference was noted, with the failure group having a lesser extent of reduction. Most previous investigations have focused on dominant fibroid volume and not measured totals. We demonstrated herein that the measurement of total fibroid volume changes is of greater clinical significance and is likely of more value than the measurement of dominant fibroid volume alone. This is because most patients would have several fibroids (a solitary fibroid is a rather unusual occurrence). In addition, patients often have several fibroids that are almost equal in size. To evaluate UAE response (at MR imaging) on the basis of only the largest fibroid is to suggest that all other fibroids are of no clinical relevance. In addition, this also assumes that patients' symptoms are purely dependent on the largest fibroid, which is likely incorrect. We believe our approach of assessing the total fibroid volume has merit, but confirmation in larger studies is important.
Findings from this study also revealed a significantly greater number of patients with pedunculated subserosal fibroids in the failure group. To our knowledge, this has not been described previously in the literature. The reasons for this may be twofold: A limited number of studies have assessed the effect of fibroid location on clinical outcomes (6, 12, 13, 14), and many groups do not perform UAE in patients with pedunculated subserosal fibroids. Of the studies in which fibroid location was evaluated, two excluded all patients with pedunculated subserosal fibroids (6, 14) and two did not categorize pedunculated subserosal fibroids separately (12, 13). Thus, to our knowledge, no investigators have conducted an analysis similar to that presented herein. It is noteworthy that submucosal fibroids have been previously reported to reduce in volume to a greater extent after embolization and this was consistent in this study (12, 14).
The presence of pedunculated subserosal fibroids has been considered a relative contraindication to UAE mainly due to the potential risk of separation from the uterus after stalk necrosis (1, 15). This was described in one report in which a septic pedunculated fibroid involved the bowel and necessitated surgical management with partial bowel resection (16). More recently, Katsumori et al (17) retrospectively reviewed 196 patients who underwent UAE at their institution and found 15 pedunculated subserosal fibroids in 12 patients. There were no complications in any of these patients at a mean follow-up time of 18 months. This group's fibroid infarction rate was similar to that obtained in our study. Katsumori et al reported clinical success in all these patients, with substantial symptom improvement and 100% satisfaction after 4-month follow-up. Although the latter study assessed only patients with pedunculated subserosal fibroids, their results significantly differ from those of the present study. Eighteen patients had at least one pedunculated subserosal fibroid, and these patients were evenly split between the success and failure groups. This may be due to differences in the methods used for clinical follow-up, our broad definition of clinical failure, the small sample size in both reports, and the fact that our study's follow-up period was longer at an average of 15 months.
Analysis of the characteristics of fibroids on the basis of location further revealed pedunculated subserosal fibroids to reduce in volume to a lesser extent in the failure group. It is unclear whether this is of clinical significance considering the small number of patients with these fibroids in the two groups. However, this observation may be explained by uterine arterial distribution where uterine artery blood flows preferentially to the inner aspects of the uterus (12). Aziz et al (18) also demonstrated smaller amounts of embolic material within the outer parts of the myometrium when embolic material was injected into the uterine artery. Thus, we speculate that greater uterine arterial supply to submucosal and intramural fibroids may permit more substantial delivery of embolic material during UAE and, conversely, lesser delivery to outer fibroids. Although beyond the scope of this study, a trend toward lesser volume reduction in subserosal and pedunculated subserosal fibroids compared to submucosal and intramural fibroids was observed. Pedunculated subserosal fibroids may also grow away from the uterus and develop a specific feeding artery and blood supply from other vascular structures such as the ovarian arteries (19). Clinical failure in patients with pedunculated subserosal fibroids may also stem from the location of these fibroids within the pelvis and interference with surrounding structures. Despite infarction and some reduction in volume, these fibroids may continue to protrude from the uterus and produce adverse symptoms.
The findings of this study suggest that additional factors, in particular fibroid location, must be considered in the management of uterine fibroids with embolization. It is important for practitioners to adequately discuss with patients the lower success rate of UAE in treating pedunculated subserosal fibroids and to be aware of other treatment options. In a recent case report, a large pedunculated subserosal fibroid was treated with sequential UAE and myomectomy (20). It is unclear whether this is in fact necessary considering that UAE alone may be effective in some patients. Further investigation is certainly necessary to define the role of UAE in the management of these fibroids.
There are several limitations to this study. There is no clear consensus among practitioners in different centers about the most effective embolic agent to use in UAE. In this study, polyvinyl alcohol particles were employed. Perhaps the use of other embolic materials may result in different results. The number of patients, particularly in the failure group, is small. Larger numbers will provide further clarification. Our imaging follow-up occurred 4 months after UAE, whereas our final clinical follow-up was completed at approximately 15 months. Changes can certainly occur with respect to fibroid volumes and perfusion in this time period, as has been documented by others (9, 13). One of the most important limitations in this study is the methodology used for clinical assessment and the overall definition of failure. The interpretation of clinical outcomes is highly subjective and, unfortunately, always present in similar research studies. Considering the importance of the results presented herein and the lack of comparable studies, further investigation with a larger number of subjects and more long-term imaging and clinical follow-up is warranted to determine the role of fibroid location on clinical outcomes.
In summary, despite technically successful embolization of the uterine arteries, some patients may not have resolution of their symptoms. Although fibroid infarction rates were similar between the clinical success and the clinical failure groups, those patients with lesser clinical improvement generally have less uterine and fibroid volume reduction after embolization. Among other potential causes, our data suggest that these patients may be more likely to have pedunculated subserosal fibroids, which appear to have less volume reduction after embolization than fibroids in other locations. We believe additional study of this question is important for assessing the extent to which these fibroids may contribute to UAE failure.
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None of the authors have identified a conflict of interest.
PII: S1051-0443(08)00007-9
doi:10.1016/j.jvir.2007.12.454
© 2008 SIR. Published by Elsevier Inc. All rights reserved.
Volume 19, Issue 5 , Pages 662-667, May 2008