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Published online before print August 14, 2006, 10.1148/radiol.2411051075
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(Radiology 2006;241:181-189.)
© RSNA, 2006

Genitourinary Imaging

Uterine Fibroids: Contrast-enhanced MR Angiography to Predict Ovarian Artery Supply—Initial Experience1

Thomas J. Kroencke, MD, Christian Scheurig, MD, Claudia Kluner, MD, Matthias Taupitz, MD, PhD, Jörg Schnorr, DVM and Bernd Hamm, MD

1 From the Department of Radiology, Charité Universitätsmedizin Berlin, Campus Mitte, Schumannstrasse 20/21, 10117 Berlin, Germany. Received June 27, 2005; revision requested August 23; revision received November 8; final version accepted January 2, 2006. Address correspondence to T.J.K. (e-mail: thomas.kroencke{at}charite.de).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Purpose: To prospectively evaluate the diagnostic performance of contrast material–enhanced magnetic resonance (MR) angiography in helping predict ovarian artery supply of uterine fibroids by using postembolization conventional aortography as the reference standard.

Materials and Methods: The protocol for the study was approved by the institutional review board, and each patient gave informed consent. Ninety consecutive women (mean age, 42.5 years; range, 33–63 years) underwent MR angiography before uterine artery embolization (UAE). The number and origin of the ovarian arteries were determined. Ovarian artery supply of fibroids was graded as very unlikely, possible, or very likely by using a scoring system based on a combination of MR angiographic findings. MR angiographic results were compared with those of conventional aortography performed after UAE in all patients and followed by selective angiography in case of a suspected ovarian artery supply of fibroids. Analysis of the association between MR angiographic grading and conventional angiography as the standard of reference was performed with a {chi}2 trend test. Sensitivity and specificity, including exact 95% confidence intervals (CIs), of MR angiography were determined.

Results: MR angiography depicted 18 ovarian arteries (four bilateral, 10 unilateral), one with an atypical origin. Five ovarian arteries were classified as very likely; three, as possible; and 10, as very unlikely sources of arterial fibroid supply. Seven (39%) of 18 ovarian arteries detected at MR angiography were visible at conventional aortography. Fibroid supply was verified at selective angiography in five ovarian arteries in five (6%) of 90 patients. There was a strong association between MR angiographic grading and the results of conventional angiography (P = .002). Sensitivity of MR angiography in depicting ovarian artery supply (grade, possible or very likely) was 100% (five of five, 95% CI: 48%; 100%) and specificity was 77% (10 of 13, 95% CI: 46%; 95%).

Conclusion: Contrast-enhanced MR angiography can help predict ovarian artery supply of uterine fibroids.

© RSNA, 2006


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Uterine artery embolization (UAE) is an effective treatment alternative to surgery in patients with symptomatic fibroids (1–5). It has been shown that infarction of fibroid tissue occurs after UAE, and recent studies (6–8) have linked early and late clinical failure to incomplete infarction of fibroids. Besides technical causes, collateral ovarian artery supply of fibroids has been reported as a cause of incomplete infarction of targeted fibroids and subsequent clinical failure of the procedure (9,10). Flush aortography at the time of UAE has been advocated to identify ovarian artery collateral supply of uterine fibroids, which may be present in 5%–8% of cases as reported in larger series (11–13). This approach subjects all patients undergoing UAE to additional radiation exposure but alters treatment in only 6% of them (13). Moreover, detection of ovarian artery collateral supply may warrant a more extensive embolization procedure, including ovarian artery embolization (OAE), which adds procedure time and radiation exposure to the patient and may carry additional risks beyond those of standard UAE. It is therefore desirable to identify patients with ovarian artery supply of fibroids during preprocedure evaluation to enable adequate counseling and treatment planning.

Magnetic resonance (MR) imaging is increasingly being used to evaluate patients before UAE because of its precision in helping determine the size and location of uterine fibroids and helping exclude other diseases (14,15). The purpose of our study, therefore, was to prospectively evaluate the diagnostic performance of contrast material–enhanced MR angiography in helping predict ovarian artery supply of uterine fibroids by using postembolization aortography as the reference standard.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
This prospective study included 90 consecutive women (mean age, 42.5 years; range, 33–63 years) who were scheduled to undergo UAE between October 2002 and May 2004 as an alternative to surgery for symptomatic fibroids. All patients underwent MR imaging, including contrast-enhanced MR angiography, as part of the preinterventional work-up. Patients complained either of bulk-related symptoms or heavy menstrual bleeding, had previously been evaluated by referring gynecologists, and refused surgery for current complaints. Previous surgical procedures and other background information are given in Table 1. The protocol for the entire study was approved by the institutional review board. In addition, each patient gave informed consent.


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  		Table 1. Baseline Data of 90 Patients

 
MR Imaging Technique
All patients underwent MR imaging with a 1.5-T superconducting imager (Magnetom Vision or Magnetom Symphony; Siemens Medical Systems, Erlangen, Germany) and a torso phased-array coil. After an initial localization scanning, transverse, coronal, and sagittal breath-hold T2-weighted half-Fourier single-shot turbo spin-echo images covering the uterus were obtained. The field of view for MR angiography was tailored to include the downstream abdominal aorta from the level of the renal arteries down to the inguinal ligament, with volume coverage of the aorta and the branching vessels of the hypogastric arteries. The circulation time was determined at the level of the aortic bifurcation by using a two-dimensional spoiled gradient-echo sequence and a test bolus injection of 2 mL of gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany). On the basis of the circulation time, contrast-enhanced MR angiography was performed during end-inspiratory breath hold in the arterial phase by utilizing a three-dimensional spoiled gradient-echo sequence in the coronal plane (Table 2). Gadopentetate dimeglumine was administered as a bolus at a weight-adjusted dose (0.2 mmol per kilogram of body weight). All injections were administered with an MR power injector (Spectris; Medrad, Pittsburgh, Pa) at a flow rate of 2 mL/sec, followed by a flush of 20 mL of normal saline solution through a 22-gauge injection cannula placed in an antecubital vein.


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  		Table 2. MR Imaging Parameters

 
Embolization and the Reference Standard
Bilateral embolization of the uterine arteries was performed by an interventional radiologist (T.J.K., with more than 5 years of experience in pelvic embolization procedures) using a transfemoral approach. After an initial hypogastric arteriogram was obtained by using the road-map technique, direct superselective catheterization of both uterine arteries was performed with road-map guidance by using 4- and 5-F end-hole catheters or a coaxially advanced microcatheter at the discretion of the operator. Embolization was achieved by deploying 500–700- and 700–900-µm-diameter gelatin-coated trisacryl microspheres (Embosphere; Biosphere Medical, Paris, France) or 500–700- and 700–900-µm-diameter polyvinyl alcohol spheres (BeadBlock; Biocompatibles, Farnham, Great Britain). The angiographic end point of embolization was the devascularization of the perifibroid plexus and sluggish antegrade flow in both uterine arteries. A flush aortogram with a 4-F pigtail catheter positioned above the level of the renal arteries was obtained after completion of bilateral UAE and served as the reference standard.

In the presence of an enlarged ovarian artery, defined as a vessel equal in size or exceeding the diameter of the 4-F pigtail catheter and extending visibly into the pelvis, selective catheterization of the respective ovarian artery was performed. OAE was performed with 700–900-µm-diameter trisacryl microspheres and supplemental gelatin sponge particles (Gelastypt, Braun, Germany) until stasis was observed in case of a verified ovarian artery supply of fibroids either at the time of UAE or a subsequent intervention based on previously obtained patient consent. Embolization was performed with local anesthesia and after intravenous administration of 750 mg cefuroxime and 500 mg metronidazole. Pain management after the procedure consisted of continuous intravenous infusion of a combination of metamizol and pethidine and a nonsteroid antiinflammatory drug administered as a suppository or, in selected cases of severe postinterventional pain, a patient-controlled intravenous opiate pump.

Data Collection
All MR images were assessed in consensus by two radiologists (M.T., C.K., with more than 10 and 3 years, respectively, of experience in abdominal MR imaging) using a digital workstation (MagicView; Siemens Medical Systems, Erlangen, Germany) that allows interactive analysis of images, as well as generation of maximum intensity projections (MIPs) and multiplanar reformations. The complete evaluation of MR data sets was performed prior to conventional angiography and interventional treatment.

The T2-weighted MR images were used to determine the number of uterine fibroids per patient, which were categorized as singular, two to five leiomyomas, and more than five leiomyomas. The location of the dominant (ie, largest) fibroid within the uterine wall was classified as subserosal, intramural, or submucosal. The volumes of the uterus and of the dominant fibroid were measured by using the formula of a prolate ellipsoid (length x width x height x 0.523). These baseline measurements are given in Table 1.

The presence or absence of uterine arteries was recorded for each case. The ovarian arteries were classified as unilateral or bilateral, and the origin of the artery was determined, if possible. Visibility of the ovarian artery on MIPs or multiplanar reformations of source images only was also recorded, and the visible length of the artery was graded by dividing the downward course of the vessel into three segments (upper, middle, lower third). The size of the ovarian artery was compared with that of an ipsilateral lumbar artery and was classified as smaller, equal, or larger in diameter. To make a prediction about the likelihood of ovarian artery supply of fibroids based on MR angiographic findings, a modification of the criteria published in the angiographic literature, such as overall visibility of the ovarian artery, vessel size, and visible extension of the ovarian artery into the pelvis, was used (12,13,16). A scoring system with subscores ranging from zero to two for the MR angiographic findings was used. Summary scores ranging from zero to six points were calculated for each ovarian artery and were used to grade the ovarian artery supply of uterine fibroids as very unlikely, possible, or very likely (Table 3).


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  		Table 3. Ovarian Artery Scoring and Grading Scheme for Findings at MR Angiography

 
Statistical Analysis
Results of contrast-enhanced MR angiography and conventional aortography were compared with respect to the number and origin of ovarian arteries identified. Among patients with an ovarian artery identified at MR angiography, the analysis of the association of MR angiographic findings with regard to the grade of ovarian artery supply of fibroids and the results of conventional angiography was performed by using a {chi}2 trend test. Significance was accepted for P ≤ .05. The sensitivity and specificity, including Clopper-Pearson exact 95% confidence intervals, of MR angiography in depicting ovarian artery supply of fibroids were determined by using postembolization conventional angiography as the reference standard.

Ovarian arteries graded at MR angiography as possible or very likely supplying uterine fibroids were regarded as positive results, whereas ovarian arteries graded as very unlikely supplying uterine fibroids were regarded as negative results in this calculation. Ovarian arteries with proved supply of fibroids at selective angiography were regarded as positive results. Negative conventional angiography results were defined as no filling of fibroid branches at selective angiography, an ovarian artery not fulfilling the criteria to pursue selective angiography (a vessel smaller than the size of the 4-F pigtail catheter and no visible extension into the pelvis), or an absent ovarian artery at angiography. The positive and negative predictive values for an ovarian artery graded a very likely or a very unlikely supply of uterine fibroids at MR angiography were calculated. Statistical analysis was performed by using StatXact (version 6.0, 2003; Cytel, Cambridge, Mass) and SPSS (version 11.5, 2002; SPSS, Chicago, Ill) software.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Ovarian Arteries at MR Angiography
Preinterventional contrast-enhanced MR angiography depicted at least one ovarian artery in 14 (16%) of 90 patients. A total of 18 ovarian arteries were detected at MR angiography, of which four were bilateral and 10 were unilateral (four right sided and six left sided). None of the patients had an absent uterine artery based on MR angiographic findings. Five ovarian arteries were identified at MR angiography to arise from the abdominal aorta below the level of the renal arteries. One ovarian artery originated aberrantly from a renal artery supplying the lower pole of the respective kidney (Fig 1). The origin could not be identified in 12 ovarian arteries. Ten (56%) of 18 ovarian arteries were smaller in size compared with an adjacent lumbar artery and only segmentally visible on multiplanar reformations of source images and, therefore, were classified as a very unlikely source of collateral arterial supply of fibroids. Three (17%) of 18 ovarian arteries were equal in size compared with an adjacent lumbar artery and were visible on reformatted source images for up to two-thirds of the expected vessel length; a collateral supply of fibroids was graded as possible (Fig 2). Five of (28%) 18 ovarian arteries were larger in size than an adjacent lumbar artery and were clearly visible on MIPs. Four of five ovarian arteries were visible in their entire vessel length. A collateral arterial supply of fibroids was therefore deemed very likely for these five ovarian arteries.


Figure 1
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  		Figure 1a: Patient 1. (a) MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) in 43-year-old woman before UAE shows enlarged left ovarian artery (arrows) with typical corkscrew appearance in more than two-thirds of its course down to small pelvis and enlarged uterine arteries (arrowheads). Note small size of left kidney (*) with perfusion of only lower two-thirds of parenchyma. (b) Completion conventional aortogram after UAE with pigtail catheter at level of renal arteries confirms enlarged left ovarian artery (arrow). (c) Angulated targeted MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) depicts left lower pole renal artery (arrow) giving off the ovarian artery. (d) Selective digital subtraction angiogram confirms aberrant origin of left ovarian artery (arrow). Branching vessels (arrowhead) supplying uterine fibroid are seen.

 

Figure 1
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  		Figure 1b: Patient 1. (a) MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) in 43-year-old woman before UAE shows enlarged left ovarian artery (arrows) with typical corkscrew appearance in more than two-thirds of its course down to small pelvis and enlarged uterine arteries (arrowheads). Note small size of left kidney (*) with perfusion of only lower two-thirds of parenchyma. (b) Completion conventional aortogram after UAE with pigtail catheter at level of renal arteries confirms enlarged left ovarian artery (arrow). (c) Angulated targeted MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) depicts left lower pole renal artery (arrow) giving off the ovarian artery. (d) Selective digital subtraction angiogram confirms aberrant origin of left ovarian artery (arrow). Branching vessels (arrowhead) supplying uterine fibroid are seen.

 

Figure 1
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  		Figure 1c: Patient 1. (a) MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) in 43-year-old woman before UAE shows enlarged left ovarian artery (arrows) with typical corkscrew appearance in more than two-thirds of its course down to small pelvis and enlarged uterine arteries (arrowheads). Note small size of left kidney (*) with perfusion of only lower two-thirds of parenchyma. (b) Completion conventional aortogram after UAE with pigtail catheter at level of renal arteries confirms enlarged left ovarian artery (arrow). (c) Angulated targeted MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) depicts left lower pole renal artery (arrow) giving off the ovarian artery. (d) Selective digital subtraction angiogram confirms aberrant origin of left ovarian artery (arrow). Branching vessels (arrowhead) supplying uterine fibroid are seen.

 

Figure 1
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  		Figure 1d: Patient 1. (a) MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) in 43-year-old woman before UAE shows enlarged left ovarian artery (arrows) with typical corkscrew appearance in more than two-thirds of its course down to small pelvis and enlarged uterine arteries (arrowheads). Note small size of left kidney (*) with perfusion of only lower two-thirds of parenchyma. (b) Completion conventional aortogram after UAE with pigtail catheter at level of renal arteries confirms enlarged left ovarian artery (arrow). (c) Angulated targeted MIP from coronal T1-weighted gradient-echo MR angiography (2.99/1.22) depicts left lower pole renal artery (arrow) giving off the ovarian artery. (d) Selective digital subtraction angiogram confirms aberrant origin of left ovarian artery (arrow). Branching vessels (arrowhead) supplying uterine fibroid are seen.

 

Figure 2
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  		Figure 2a: Patient 3. (a) Coronal multiplanar reformation from preinterventional T1-weighted contrast-enhanced gradient-echo MR angiogram (2.99/1.22) in a 40-year-old woman shows left ovarian artery (arrows) of small caliber in about two-thirds of its course down into the pelvis. Uterus (*) is markedly enlarged. (b) On selective angiogram, gentle hand injection after superselective catheterization of left ovarian artery shows typical perifibroid plexus vessels (arrow) supplied by ovarian artery (arrowheads).

 

Figure 2
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  		Figure 2b: Patient 3. (a) Coronal multiplanar reformation from preinterventional T1-weighted contrast-enhanced gradient-echo MR angiogram (2.99/1.22) in a 40-year-old woman shows left ovarian artery (arrows) of small caliber in about two-thirds of its course down into the pelvis. Uterus (*) is markedly enlarged. (b) On selective angiogram, gentle hand injection after superselective catheterization of left ovarian artery shows typical perifibroid plexus vessels (arrow) supplied by ovarian artery (arrowheads).

 
Conventional Angiography and OAE
Hypogastric arteriograms obtained prior to UAE confirmed no cases of absent uterine artery, and bilateral UAE was technically successful in all 90 patients. Post-UAE flush aortography depicted seven of 18 ovarian arteries visible at MR angiography. All seven ovarian arteries detected at conventional aortography were identified previously at MR angiography. Conversely, 11 ovarian arteries seen at MR angiography were not detected at post-UAE aortography. Conventional angiography depicted no ovarian arteries besides those identified at preinterventional MR angiography. All ovarian arteries detected on a conventional angiogram were unilaterally (two right sided, five left sided) visible on the completion aortogram obtained after UAE. Of the seven unilaterally visible ovarian arteries, five originated from the aorta below the renal arteries and two originated from a lower pole artery supplying the ipsilateral kidney (Figs 1, 2). Two ovarian arteries were smaller, one was equal in size, and four were larger than the diameter of the 4-F pigtail catheter inserted for post-UAE flush aortography. Five ovarian arteries with a diameter equal to or larger than the 4-F catheter were visible throughout their entire course down to the pelvis and subsequently were catheterized selectively. All five ovarian arteries showed branching vessels supplying portions of uterine fibroids at selective angiography. Embolization was performed in four of the five cases (Fig 3). In three patients, OAE was performed at the time of UAE. OAE was performed in one patient during a second intervention after failure of clinical improvement. One patient opted not to undergo OAE at the time of UAE. No complications occurred during UAE or additional OAE.


Figure 3
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  		Figure 3a: Patient 5. (a) Targeted preinterventional MIP from coronal T1-weighted contrast-enhanced gradient-echo MR angiography (2.99/1.22) in a 38-year-old woman depicts an enlarged ovarian artery (arrow) visibly taking its course into the pelvis. (b) Catheter flush aortogram obtained after UAE shows enlarged left-sided ovarian artery (arrow) visible in its entire course from below renal artery to the small pelvis. Left uterine artery (arrowhead) was catheterized with a second catheter. (c) Selective angiogram before embolization proves direct supply of large uterine fibroid (arrow). Parenchymal blush of the left ovary (arrowhead) is also seen. (d) Selective angiogram after OAE with 700–900-µm gelatin-coated trisacryl microspheres and gelatin sponge particles confirms stasis within left ovarian artery (arrow), absent filling of fibroid vessels, and no opacification of left ovary.

 

Figure 3
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  		Figure 3b: Patient 5. (a) Targeted preinterventional MIP from coronal T1-weighted contrast-enhanced gradient-echo MR angiography (2.99/1.22) in a 38-year-old woman depicts an enlarged ovarian artery (arrow) visibly taking its course into the pelvis. (b) Catheter flush aortogram obtained after UAE shows enlarged left-sided ovarian artery (arrow) visible in its entire course from below renal artery to the small pelvis. Left uterine artery (arrowhead) was catheterized with a second catheter. (c) Selective angiogram before embolization proves direct supply of large uterine fibroid (arrow). Parenchymal blush of the left ovary (arrowhead) is also seen. (d) Selective angiogram after OAE with 700–900-µm gelatin-coated trisacryl microspheres and gelatin sponge particles confirms stasis within left ovarian artery (arrow), absent filling of fibroid vessels, and no opacification of left ovary.

 

Figure 3
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  		Figure 3c: Patient 5. (a) Targeted preinterventional MIP from coronal T1-weighted contrast-enhanced gradient-echo MR angiography (2.99/1.22) in a 38-year-old woman depicts an enlarged ovarian artery (arrow) visibly taking its course into the pelvis. (b) Catheter flush aortogram obtained after UAE shows enlarged left-sided ovarian artery (arrow) visible in its entire course from below renal artery to the small pelvis. Left uterine artery (arrowhead) was catheterized with a second catheter. (c) Selective angiogram before embolization proves direct supply of large uterine fibroid (arrow). Parenchymal blush of the left ovary (arrowhead) is also seen. (d) Selective angiogram after OAE with 700–900-µm gelatin-coated trisacryl microspheres and gelatin sponge particles confirms stasis within left ovarian artery (arrow), absent filling of fibroid vessels, and no opacification of left ovary.

 

Figure 3
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  		Figure 3d: Patient 5. (a) Targeted preinterventional MIP from coronal T1-weighted contrast-enhanced gradient-echo MR angiography (2.99/1.22) in a 38-year-old woman depicts an enlarged ovarian artery (arrow) visibly taking its course into the pelvis. (b) Catheter flush aortogram obtained after UAE shows enlarged left-sided ovarian artery (arrow) visible in its entire course from below renal artery to the small pelvis. Left uterine artery (arrowhead) was catheterized with a second catheter. (c) Selective angiogram before embolization proves direct supply of large uterine fibroid (arrow). Parenchymal blush of the left ovary (arrowhead) is also seen. (d) Selective angiogram after OAE with 700–900-µm gelatin-coated trisacryl microspheres and gelatin sponge particles confirms stasis within left ovarian artery (arrow), absent filling of fibroid vessels, and no opacification of left ovary.

 
MR Angiographic Prediction of Ovarian Artery Supply
Ovarian artery supply of fibroids was suspected on the basis of MR angiographic findings in eight (44%) of 18 ovarian arteries detected in eight (9%) of 90 patients (Table 4). Subsequent conventional angiography helped confirm ovarian artery supply in five (63%) of eight vessels in five (6%) of 90 patients. There was a strong association between the grading at preinterventional MR angiography and the demonstration of ovarian artery supply of fibroids at subsequent conventional angiography (P = .002). With regard to conventional angiography as the standard of reference, MR angiography had a sensitivity of 100% (five of five, 95% confidence interval: 48%; 100%) and a specificity of 77% (10 of 13, 95% confidence interval: 46%; 95%) in depicting ovarian artery supply of uterine fibroids (Table 5).


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  		Table 4. Findings in Patients Suspected of Having Ovarian Artery Supply of Fibroids at MR Angiography

 

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  		Table 5. Ovarian Artery Supply of Uterine Fibroids: Comparison of Contrast-enhanced MR Angiographic Grading and Conventional Angiographic Findings

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
ADVANCES IN KNOWLEDGE
 References
 
Partial or complete supply of uterine fibroids by the ovarian arteries has been described in the literature as a cause of treatment failure of UAE for uterine fibroids. The frequency of this type of collateral supply of uterine fibroids reported in the literature ranges from 5% to 8% (11–13). Our results confirm the rate of ovarian artery supply of fibroids reported in these studies. In none of our cases was an enlarged ovarian artery combined with an absent uterine artery, as has been reported by others (17). In our study, we saw two patients with aberrant ovarian arteries that originated from a renal artery supplying the lower pole of the respective kidney, a variation that has been described in the literature to be present in 8%–20% of cases in cadaveric studies (18,19).

Because of their origin, ovarian arteries are usually not visualized on pelvic angiograms obtained prior to UAE. A collateral supply of uterine fibroids will therefore be missed if no additional flush aortograms are obtained. A completion aortogram that allows identification of ovarian artery supply and helps confirm occlusion of uterine arteries has been favored by some over a pre-UAE aortogram (12,17). Some authors perform aortography before and after UAE, which adds about 4.1 mSV to the effective dose for each patient (11,13,20). Others take a "wait-and-see" approach and reserve aortography for those cases in which UAE is a clinical failure (21). However, acquisition of a flush aortogram only in cases of clinical failure, which becomes obvious 3–4 months after UAE at the earliest, still leaves at least 5%–8% of all patients with the prospect of a second invasive angiography study to verify and treat ovarian artery supply of fibroids.

Our findings show that preinterventional contrast-enhanced MR angiography can depict ovarian arteries and help discriminate between ovarian arteries that have a negligible versus high probability of supplying uterine fibroids. By using the grading scheme described here, aortography after UAE to help detect ovarian artery collateral supply can be restricted to those cases in which MR angiography depicts an ovarian artery and findings suggest a high probability of fibroid supply. On the basis of our results, routine aortography could have been prevented without any compromise in diagnostic safety in 82 (91%) of 90 patients.

Interestingly, postembolization aortography depicted only seven of 18 ovarian arteries seen at MR angiography. These seven arteries were part of a group of eight enlarged ovarian arteries suspected of being a collateral supply of uterine fibroids at MR angiography. Our observation that the majority of ovarian arteries identified at MR angiography before UAE are not visible after embolization is in accordance with angiographic study findings (11,13). Possible explanations were given by Binkert et al (13), who attributed this observation either to a reduction in the "sump effect" of the fibroids with reduced demand through the utero-ovarian anastomosis or to a retrograde embolic occlusion of the anastomosis after UAE. Razavi et al (11) showed that in cases in which the ovarian artery and the uterine artery join and then jointly supply the fibroids, occlusion of the fibroid-supplying uterine artery branches at UAE may terminate flow by means of the ovarian artery-to–uterine artery anastomoses owing to the increased resistance in the vascular bed. They further concluded that in this type of ovarian artery–to–uterine artery anastomosis (referred to as type Ia anastomosis), the ovarian artery is typically not seen on aortograms obtained after UAE and is unlikely to be a source of procedural failure.

Even if markedly dilated ovarian arteries are discovered on pre-UAE aortograms, they may not be visible in up to 63% of cases on post-UAE aortograms, as noted by Binkert et al (13). It may be speculated that a type Ia anastomosis was present in one case (patient 8) in our study. The mere presence of an enlarged ovarian artery at preinterventional MR angiography, therefore, does not imply that this artery is invariably a major and independent supply to uterine fibroids. However, in patients in whom the ovarian artery supplies the fibroids directly, persistent flow to uterine fibroids via the ovarian artery can be observed after UAE, as illustrated by the findings in five patients of our study. It should be noted that UAE alone is unlikely to be effective in these cases.

There are technical limitations of contrast-enhanced MR angiography compared with arterial flush aortography in detecting relevant ovarian artery supply. The in-plane resolution of the MR angiographic sequence used in this study was 1.8 mm, while digital subtraction aortography can depict vessels below this threshold. However, ovarian arteries need to be at least 1.5 mm in diameter to be visible on a flush aortogram with certainty (13,16). MR angiography reliably depicts ovarian arteries, which are likely to constitute a collateral supply of fibroids based on size and visibility of the vessels, but lacks the additional dynamic information of an angiographic run, which may show directly the arterial flow to uterine fibroids.

There were also limitations to the design of this study. First, we did not compare MR angiography with pre-UAE aortography. Therefore, one can only speculate about the 11 additional ovarian arteries seen at MR angiography but not at post-UAE aortography. We further acknowledge that classification of those ovarian arteries that were seen at MR aortography but were not enlarged or visible at aortography as negative results with regard to ovarian artery supply of fibroids may have led to a work-up bias, since these vessels were not further investigated. As a consequence, the sensitivity of MR aortography in the current study may be overestimated, while the specificity may be rather underestimated. However, it seems unlikely that ovarian arteries not seen at postembolization aortography are supplying uterine fibroids.

In the present study, the decision to perform selective angiography after UAE was based on the visibility of the vessel on the completion angiogram by using modifications of criteria reported (12,13,16). A vessel size equal to or larger than the 4-F catheter used (diameter, 1.3 mm) served as the threshold, since in the absence of ovarian or uterine disease the ovarian artery seldom exceeds 1 mm in diameter (22).

A further limitation of this study was the fact that the grading and scoring scheme used for MR angiographic findings is one of many potential systems. The proposed scheme proved to be feasible but has not been compared with other schemes, and different approaches might also be useful. Interobserver readings to determine the reliability of this scheme might have been helpful in this respect but were not performed in this study.

In conclusion, our work shows that contrast-enhanced MR angiography allows identification of those patients in whom the ovarian arteries need to be assessed after UAE. The data from this limited study suggest that conventional aortography performed at the time of UAE can be avoided in most patients if MR angiographic findings are negative for ovarian artery supply of fibroids on the basis of the grading scheme we used.


   ADVANCES IN KNOWLEDGE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
References
 


   ACKNOWLEDGMENTS
 
The authors thank Tania Schink, MSc, Department of Biostatistics, Charité Universitätsmedizin Berlin, for statistical consultation and review.


   FOOTNOTES
 

Abbreviations: MIP = maximum intensity projection • OAE = ovarian artery embolization • UAE = uterine artery embolization

Authors stated no financial relationship to disclose.

Author contributions: Guarantor of integrity of entire study, T.J.K.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, T.J.K., C.S., J.S.; clinical studies, T.J.K., C.K., M.T.; statistical analysis, T.J.K., C.S., M.T.; and manuscript editing, all authors


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 

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