Urethral Bulking Agents: Imaging Review
Mellena D. Bridges1,
Steven P. Petrou2 and
Deborah J. Lightner3
1 Department of Radiology, Mayo Clinic Jacksonville, 4500 San Pablo Rd.,
Jacksonville, FL 32224.
2 Department of Urology, Mayo Clinic Jacksonville, Jacksonville, FL.
3 Department of Urology, Mayo Clinic, Rochester, MN.
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Fig. 1A —Series of fluoroscopic spot radiographs of pelvis obtained
during course of urethral bulking procedure. Preinjection image.
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Fig. 1B —Series of fluoroscopic spot radiographs of pelvis obtained
during course of urethral bulking procedure. Image obtained during injection
shows accumulation of radiodense material (Durasphere, Carbon Medical
Technologies) around lower urethra and to right of upper urethra
(arrows). Notice urethral catheter with its retention balloon and
opacification of bladder.
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Fig. 1C —Series of fluoroscopic spot radiographs of pelvis obtained
during course of urethral bulking procedure. Postprocedure image with bulking
material that is now also to left of upper urethra, near bladder base. Note
small foci of venous or lymphatic intravasation (arrows).
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Fig. 2A —Comparative CT densities of bulking agents in vitro. Scout
image from CT shows three syringes containing, from left to right, new
Durasphere (Carbot Medical Technologies) formulation (arrowhead),
collagen (asterisk), and old Durasphere formulation
(arrow).
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Fig. 2B —Comparative CT densities of bulking agents in vitro. Axial CT
image of same three syringes using soft-tissue settings.
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Fig. 2C —Comparative CT densities of bulking agents in vitro. Axial CT
image of same three syringes using bone settings. Greater density of older
Durasphere formulation is more obvious on bone window settings.
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Fig. 3A —CT appearance in 68-year-old woman of periurethral collagen
injected approximately 6 months previously. Unenhanced axial CT image obtained
during triphasic examination of abdomen and pelvis. Collagen deposits are
difficult to discern.
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Fig. 3B —CT appearance in 68-year-old woman of periurethral collagen
injected approximately 6 months previously. Avascular collagen
(arrow) is more readily seen during arterial phase after
administration of contrast agent as adjacent tissues begin to enhance.
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Fig. 3C —CT appearance in 68-year-old woman of periurethral collagen
injected approximately 6 months previously. After delay of several minutes,
collagen (arrow) becomes more apparent.
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Fig. 4A —Variable MRI appearance of collagen. T2-weighted image shows
collection of hyperintense collagen (black arrow), which was recently
injected into a tissue phantom. Compare with signal intensity of cerebrospinal
fluid (CSF) (white arrow).
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Fig. 4B —Variable MRI appearance of collagen. Coronal T2-weighted
HASTE image in 72-year-old woman shows bulky urethra and elevated urethral
neck (arrow). Here, collagen is isointense with urethral tissue.
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Fig. 4C —Variable MRI appearance of collagen. Axial fat-suppressed
T2-weighted image in same patient. Relative signal intensity scale has shifted
so that periurethral collagen (arrows) is now hypointense to
urethra.
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Fig. 5A —MRI was requested to evaluate 63-year-old woman for urethral
diverticulum who had history of recurrent urinary tract infections and firm
urethral mass on physical examination. On postoperative histopathology, this
proved to be urethral leiomyoma. Axial T2-weighted turbo spin-echo image
through the level of urethra shows fairly homogeneous, isointense mass
(arrow), which displaces vagina posteriorly and is indistinguishable
from urethra.
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Fig. 5B —MRI was requested to evaluate 63-year-old woman for urethral
diverticulum who had history of recurrent urinary tract infections and firm
urethral mass on physical examination. On postoperative histopathology, this
proved to be urethral leiomyoma. Axial volumetric gradient-echo T1-weighted
image of mass (arrow) at same level obtained immediately after IV
administration of gadolinium. Faint, but unmistakable enhancement proves this
is neither bulking agent nor urethral diverticulum. Compare with
Figure 6D.
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Fig. 6A —MRI of 74-year-old woman with history of urethral collagen
injection 4 years previously for urinary incontinence. Physical examination
revealed small, firm urethral mass, and MRI was requested to exclude urethral
neoplasm. Axial T2-weighted turbo spin-echo image shows symmetric enlargement
of urethra (arrow). Signal intensity is isointense to other perineal
soft tissues, with mild heterogeneity.
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Fig. 6B —MRI of 74-year-old woman with history of urethral collagen
injection 4 years previously for urinary incontinence. Physical examination
revealed small, firm urethral mass, and MRI was requested to exclude urethral
neoplasm. Axial image at same level from fat-suppressed volumetric
gradient-echo T1-weighted (VIBE) sequence shows isointense enlargement of
urethra (arrow).
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Fig. 6C —MRI of 74-year-old woman with history of urethral collagen
injection 4 years previously for urinary incontinence. Physical examination
revealed small, firm urethral mass, and MRI was requested to exclude urethral
neoplasm. Coronal HASTE image shows to better advantage smooth enlargement of
urethra (arrow) and its isointensity.
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Fig. 6D —MRI of 74-year-old woman with history of urethral collagen
injection 4 years previously for urinary incontinence. Physical examination
revealed small, firm urethral mass, and MRI was requested to exclude urethral
neoplasm. Gadolinium-enhanced axial VIBE image clearly shows bilateral,
nonenhancing pockets of collagen flanking urethral mucosa (arrow).
Note signal intensity of unenhanced images excludes possibility of urethral
diverticulum, which also would fail to enhance.
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Fig. 7 —Pelvic radiograph in 81-year-old woman several months after
Durasphere (Carbon Medical Technologies) injection. Note very dense
periurethral collections and small streaks of material in vicinity,
representing intravasation (arrows).
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Fig. 8A. —43-year-old woman with severe urinary incontinence after
pelvic trauma. Axial images from CT urography examination. Four Durasphere
(Carbon Medical Technologies) administrations during previous year failed to
relieve symptoms. Durasphere therapy represented as clump of extremely dense
periurethral material. Note aliasing and beam-hardening artifact in the
vicinity (arrows). Density measurements averaged 1,800 H.
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Fig. 8B. —43-year-old woman with severe urinary incontinence after
pelvic trauma. Axial images from CT urography examination. Four Durasphere
(Carbon Medical Technologies) administrations during previous year failed to
relieve symptoms. Bone window settings provide more accurate depiction of
actual extent of material.
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Fig. 8C. —43-year-old woman with severe urinary incontinence after
pelvic trauma. Axial images from CT urography examination. Four Durasphere
(Carbon Medical Technologies) administrations during previous year failed to
relieve symptoms. Oblique coronal maximum-intensity-projection reconstruction
image shows vertical extent of material and clearly shows bilateral
intravasation into pelvic vessels (arrows).
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Fig. 9A —MRI of pelvis of 58-year-old woman to evaluate pelvic floor
dysfunction. Durasphere (Carbon Medical Technologies) injection is represented
on T2-weighted turbo spin-echo (TSE) axial image by a small, extremely
hypointense focus (arrow) in the muscular wall of urethra. Rectal
tube (arrowhead) had been placed to facilitate injection of rectal
gel.
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Fig. 9B —MRI of pelvis of 58-year-old woman to evaluate pelvic floor
dysfunction. Fat-suppressed T2-weighted TSE image at same level. Note how
change in signal intensity range increases conspicuity of injected material
(arrow).
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Fig. 9C —MRI of pelvis of 58-year-old woman to evaluate pelvic floor
dysfunction. Coronal single-shot T2-weighted image shows bulked-up,
low-signal-intensity urethra bulging upward into bladder base
(arrow).
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Fig. 10 —Axial gadolinium-enhanced volumetric gradient-echo
T1-weighted image in 77-year-old woman clearly shows periurethral pocket of
nonenhancing microbead bulking material (arrow) adjacent to and
slightly displacing urethra (arrowhead).
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Fig. 11A —54-year-old woman with stress urinary incontinence treated
with periurethral injection of new Durasphere (Carbon Medical Technologies)
formulation. Because of its diminished density, new agent is indiscernible on
conventional pelvic radiography.
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Fig. 11B —54-year-old woman with stress urinary incontinence treated
with periurethral injection of new Durasphere (Carbon Medical Technologies)
formulation. Axial image from CT scan obtained same day clearly shows
Durasphere (arrow) as hyperdense periurethral collection. Material
extends into, or immediately adjacent to, wall of left bladder base,
suggesting overzealous injection technique. Note reduced beam-hardening
artifact compared with artifact in Fig.
8A.
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Fig. 11C —54-year-old woman with stress urinary incontinence treated
with periurethral injection of new Durasphere (Carbon Medical Technologies)
formulation. Same CT slice displayed at bone settings. Injected material
(arrow) appears to be approximately same density as medullary bone.
Compare with Fig. 8B.
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Copyright © 2005 by the American Roentgen Ray Society.
