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one study of 28 ﬁbroids reported that avidly enhancing ﬁbroids
had greater volume reduction (8). Other studies reported to the
contrary that greater enhancement pre-UAE does not necessarily
predict better response (13-15). One study did not ﬁnd a greater
volume reduction 4 months post-UAE between 14 ﬁbroids that
were well perfused compared with 21 ﬁbroids that were not well
perfused (13). More recently, a study of 182 patients reported
that low vascularity might predict a more favorable outcome in
patients treated with embolization; it was found that patients with
lower-vascularity ﬁbroids had a lower incidence of recurrence than
patients with higher-vascularity ﬁbroids (14). Additionally, avidly
enhancing ﬁbroids rapidly decreased in size shortly after embolization but plateaued after 6 months, as opposed to less-enhancing
ﬁbroids that continued to shrink after 6 months (14). This may
explain why previous studies with a shorter follow-up period reported greater volume reduction in enhancing ﬁbroids (8, 9).
Our study adds to this literature by showing that nonenhancing and presumably necrotic ﬁbroids respond to UAE, despite
their relative avascularity. Therefore, women with necrotic ﬁbroids
should not be excluded from treatment. Though one may assume
that embolization should be more eﬀective for ﬁbroids of greater
vascularity, ﬁbroids have particularly abnormal angiogenesis and
vascularization patterns that are not completely understood. The
avascular and hypoxic environment of ﬁbroids is paradoxically
associated with more proangiogenic factors (16).
Our ﬁndings also suggest that ADC is an independent predictor of ﬁbroid shrinkage. Fibroids with higher ADC values
pre-UAE demonstrated greater shrinkage, which has been reported in other retrospective and prospective investigations (9,
15, 17). It is unclear what the degree of diﬀusion restriction of
water molecules signiﬁes, but ADC provides some information
about the molecular and/or cellular composition of masses including ﬁbroids, and it may be useful in pre-UAE patient selection. We also found that smaller ﬁbroid size predicted greater
reduction after UAE, which is in contrast to other studies that
showed either no correlation between ﬁbroid size and volume
reduction (18) or better response in larger ﬁbroids (8).
The primary limitations of this study pertain to its singlecenter retrospective nature. Our primary marker of UAE response
was restricted to ﬁbroid size instead of clinical outcomes due
to limited data availability in our medical database. The length
of follow-up was also limited due to the practice of obtaining
MRI imaging 6 months after embolization without the need for
longer-term imaging. A longer-term prospective study with a
larger sample size and clinical correlates could therefore increase
the accuracy of our evaluations and help prove that patients with
minimally or nonenhancing ﬁbroids can still beneﬁt from embolization. In addition to ﬁbroid size reduction on imaging, clinical
markers such as bleeding, pain, and recurrence could also be measured. Fibroid size is a more objective marker, reﬂects data easier to
collect, and is generally associated with symptom improvement,
but clinical markers will more accurately predict response (4, 5).
In conclusion, nonenhancing ﬁbroids respond to UAE, particularly in regard to size reduction. In addition, MRI characteristics such as ADC values may better predict response to UAE.
Especially for women who either do not desire surgery or want to
July 2017

preserve fertility, UAE may be the best option, and it is important
not to withhold therapy without clear evidence of its ineﬃcacy in
the setting of nonenhancement. These results suggest that physicians should reconsider excluding women with nonenhancing
ﬁbroids, as these patients may also beneﬁt from embolization.
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Table of Contents for the Digital Edition of Baylor University Medical Center Proceedings July 2017