Dr. Hubert is a Radiology Resident and Dr. Bergin is an Associate Professor of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA.
is the imaging modality of choice for the female pelvis. It is widely
available, has broad acceptance by patients as a “familiar test,” and is
relatively inexpensive. High-resolution imaging of transvaginal
ultrasound provides high diagnostic accuracy for pelvic pathology.
However, there are some shortcomings with this modality, such as the
limited ﬁeld of view, obscuration of pelvic organs by the presence of
bowel gas, inherent limitations dependent on patient size, and its
dependence on the skill and experience of the operator. The American
College of Radiology has provided guidelines for when ultrasound is an
appropriate imaging tool (Table 1) for the evaluation of the female
With its high contrast resolution, its
ability to provide good tissue characterization, and its multiplanar
imaging capabilities, magnetic resonance imaging (MRI) is increasingly
used to evaluate pelvic pathology (Table 2).2-5 There is a
signiﬁcant difference, however, in the inherent costs of MRI and
ultrasound. The dilemma for referring physicians and general
radiologists is to decide when it is appropriate to refer patients for
MRI.5 This article describes in what situations MRI should be considered to evaluate the female pelvis.
MRI of the female pelvis at our institution includes coronal
single-shot fast spin-echo (FSE), axial T2-weighted (T2W) FSE, axial
in-phase and opposed-phase T1-weighted (T1W) gradient-recalled echo
(GRE), and sagittal T2W FSE fat-suppressed sequences utilizing a
dedicated pelvic phased-array coil (see Table 3).
axial 3-dimensional T1W GRE dynamic imaging following intravenous
administration of 20 mL of gadolinium contrast is obtained routinely.
Delayed fat-suppressed 2-dimensional (2D) GRE imaging is subsequently
obtained in another plane. If artifact from the bowel is perceived as
problematic on initial sequences, glucagon may be administered by
intramuscular (0.8 mg) or intravenous injection (0.2 mg). This is not
routinely used in the author’s institution, however. For pelvic ﬂoor
imaging, dynamic 2D GRE imaging may be performed with and without the
Valsalva maneuver, as discussed later, to detect pelvic prolapse.
the premenopausal woman, the ovaries are typically well evaluated by
ultrasound. When evaluating an adnexal mass on ultrasound, the
diagnostic challenges that may arise include accurately localizing the
mass, determining whether or not it is ovarian in origin, and, when
complex, whether it is deﬁnitively benign or malignant. Many adnexal
masses are benign and, when indicated, can be treated surgically by
laparoscopic technique. Complex echogenic adnexal lesions on ultrasound
may represent hemorrhagic cysts, endometrioma, dermoids, or ovarian
neoplasms. If a cystic adnexal mass >5 cm in a premenopausal woman or
>3 cm in a postmenopausal woman persists or increases in size on
follow-up ultrasound, MRI should be considered so that malignancy can be
excluded.5-8 MRI should also be considered when a solid or
solid cystic adnexal lesion with internal color ﬂow is detected by
ultrasound. MRI has an overall accuracy of 91% to 93% in the
characterization of adnexal masses as benign or malignant. In these
circumstances, it has been found that the use of MRI is cost-effective
in that it reduces unnecessary surgical procedures.
simple unilocular ovarian cyst is not an indication for MRI, as it is a
common incidental ﬁnding in both pre- and postmenopausal women. These
cysts are well evaluated by ultrasound. However, the postmenopausal
ovary tends to contain fewer cysts of smaller size. When they are <3
cm in size with a wall ≤3 mm and have the characteristic appearance of
low T1 and high T2 signal intensity, these cysts can be considered
benign in both populations. Studies that speciﬁcally examined the
premenopausal ovary have shown that the risk of malignancy for
unilocular cysts <5 cm in an asymptomatic woman approaches zero.
Hemorrhagic ovarian cyst and endometrioma
its high contrast resolution and its tissue characterization
capabilities, MRI is a valuable tool for the characterization of
echogenic adnexal masses detected by ultrasound. The accuracy of MRI for
identifying lesions such as hemorrhagic cysts and endometriomas is
higher than with transvaginal ultrasound imaging. On ultrasound, these
lesions are occasionally misinterpreted as solid tumors, mature cystic
teratomas, or complex cysts.5-8
Most ovarian cysts are
functional in origin and occasionally can be complicated by intracystic
hemorrhage. The MRI characteristics can be variable in this situation,
depending on the age and amount of the hemorrhagic component. In
general, however, they tend to be of relatively high signal intensity on
T1W images and of intermediate-to-high signal intensity on T2W images
and frequently reveal a ﬂuid-ﬂuid level (Figure 1). Hemorrhagic cysts
should remain of relatively high signal on T1W images with fat
suppression, which helps to differentiate them from dermoid cysts in
most situations. They also tend to have thicker walls than do simple
cysts and may exhibit wall enhancement on postcontrast images.
the internal components of the cysts should never enhance. The majority
of hemorrhagic ovarian cysts may be accurately diagnosed by ultrasound.
MRI, however, should be considered when the hemorrhagic cystic lesion
persists or increases in size on follow-up ultrasound.
is the ectopic presence of functional endometrial glands and stroma
outside the uterus. Although laparoscopy remains the standard for
diagnosing and staging pelvic endometriosis, MRI can identify lesions
obscured at laparoscopy by dense ad hesions. MRI has a sensitivity of
90%, a speciﬁcity of 98%, and an overall accuracy of 96% for the
identiﬁcation of endometriomas in patients with clinically suspected
adnexal masses.8-10 As with hemorrhagic cysts, the MRI
appearance of endometriomas is somewhat variable based on the stage and
amount of blood products. They are typically of high signal on T1W
images and of intermediate-to-low signal intensity on T2W images (Figure
2). This relatively lower signal intensity on T2W imaging, which is
often referred to as “T2-shading,” is secondary to methemoglobin,
protein, and iron from repeated episodes of hemorrhage. Endometriomas
are more frequently bilateral and usually exhibit multiplicity.
Endometriosis implants on serosal or peritoneal surfaces are identiﬁed
on MRI by high T1 signal seen on nonenhanced fat-suppressed images.
diagnosing ovarian torsion, a true gynecologic emergency ultrasound is
the modality of choice. If sonographic results are equivocal, however,
MRI may be performed. Ovarian torsion is usually the consequence of an
underlying ovarian lesion, most commonly dermoid or parovarian cysts.9 As
with hemorrhagic cysts and endometriomas, the presence of hemorrhage
leads to a variable appearance that can be further complicated by the
presence of infarction. Findings on MRI that suggest ovarian torsion
include deviation of the uterus toward the affected side, engorgement of
blood vessels toward the affected side, and a small amount of ascites.
Findings that indicate a twisted adnexal tumor include protrusion of the
lesion to the affected side, thick straight blood vessels draping over
the lesion, and complete absence of enhancement.
Fallopian tube abnormalities
of the fallopian tube commonly present as adnexal masses and generally
result from salpingitis, endometriosis, or peritubal adhesions.8 Although
readily identiﬁed with ultrasound, MRI is useful in cases of dense
scarring and in the identiﬁcation of the adjacent ovary. With a large
simple hydrosalpinx, the relatively large ﬁeld of view utilized in MRI
(as compared with ultrasound) facilitates easy recognition of its
tubular morphology, which differentiates it from a potential ovarian
cystic mass. When hydrosalpinx is complicated by pyosalpinx, the T2
signal intensity may exhibit shading or hypointense areas from the high
protein content, similar to that of an endometrioma. When complicated by
a tubo-ovarian abscess, inﬂammatory changes are seen in the surrounding
tissue. The associated inﬂammatory changes and the abscess wall exhibit
intense enhancement with contrast administration (Figure 3).
cell tumors represent 15% to 20% of all tumors of the ovary. Dermoids
account for 95% of all ovarian germ cell tumors. Most of these are
unilocular, contain sebaceous ﬂuid, and are commonly referred to as
mature cystic teratomas or dermoid cysts. Although these are usually
asymptomatic and are incidental ﬁndings in young women, the standard
treatment is surgical removal because of their potential to cause
ovarian torsion or for the cyst to rupture. There is also a rare chance
of malignant degeneration to squamous cell carcinoma. Although most
mature cystic teratomas can be diagnosed at ultrasound, one prospective
study has shown the sensitivity to be 58% with a speciﬁcity of 99%.11 Numerous
pitfalls exist in their diagnosis by ultrasound. The presence of blood
clot within a hemorrhagic cyst can appear echogenic, which causes
confusion in the diagnosis. Adjacent echogenic bowel can also be
mistaken for a mature cystic teratoma and vice versa.
MRI has a
high sensitivity for the presence of fat within the sebaceous component,
which is characteristic of nearly all these lesions. The sebaceous
component is of very high signal intensity on T1W images and is somewhat
variable on T2W images.10-12 Fat suppression can
differentiate macroscopic fat from other hemorrhagic lesions that appear
hyperintense on T1W images, such as hemorrhagic cysts and endometriomas
(Figure 4). Even the rare lesion that contains microscopic fat can be
differentiated by using chemical shift imaging with the use of in- and
out-of-phase sequences. Mature cystic teratomas also commonly have a
solid mural nodule that is referred to as a dermoid plug or a Rokitansky nodule.
Although rare, malignant transformation can occur in 1% to 2% of cases.
In these cases, the women tend to be postmenopausal and the images are
characterized by transmural extension of the solid component and, often,
by direct invasion of adjacent pelvic structures.
most common subtypes of sexcord stromal tumors are ﬁbromas,
ﬁbrothecomas, thecomas, and Brenner tumors. Although these account for
only 4% of all ovarian tumors, they are the most common solid primary
tumor of the ovary. These benign lesions are composed of dense ﬁbrous
tissue. On ultrasound, they appear as solid hypoechoic masses exhibiting
marked attenuation. It is often difﬁcult to distinguish ﬁbromas and
ﬁbrothecomas from other solid ovarian masses and pedunculated ﬁbroids on
ultrasound. On MRI, they exhibit low signal intensity on T2W images
with low-to-intermediate signal on T1W images (Figure 5).13 Small
areas of cystic degeneration and edema may be present in larger
lesions, and they tend to show mild enhancement with gadolinium
contrast. Although similar in MRI appearance to uterine leiomyomas,
their ovarian origin can be conﬁrmed by the presence of follicles in the
surrounding ovarian tissue. MRI can also exclude these lesions by
identifying the ovaries as separate from the lesion.13
carcinoma remains the leading cause of gynecological cancer-related
deaths in the United States, and it is estimated to comprise 6% of all
cancer-related deaths in 2006.14 Approximately 75% of women
have advanced disease at the time of diagnosis with a 5-year survival of
only 29% in those with metastases.12-14
screening method currently exists for the detection of ovarian cancer,
in part because the preclinical phase is estimated to be <2 years.
Current methods include transvaginal ultrasound and determining serum
CA-125 levels. Unfortunately, CA-125 is not speciﬁc for ovarian cancers.
Although MRI is clearly not cost-effective as a screening tool, it has
become quite valuable for patients in whom sonographic results are
indeterminate. As previously discussed, MRI can accurately characterize
benign masses such as teratomas and endometriomas; this has proven to be
a cost-effective approach, since unnecessary surgery can be avoided.10-12 MRI
is also superior to CT in the diagnosis of peritoneal implants and has
superior accuracy in diagnosing ovarian malignancy compared with CT and
Doppler sonography. Gadolinium-enhanced MRI has a rate of depiction of
benign lesions of 93% and of malignant lesions of 95%.10-12
ovarian neoplasms are classiﬁed as epithelial tumors (60% to 70%), germ
cell tumors (15% to 20%), and sexcord stromal tumors (5% to 10%).
However, no imaging modality can differentiate between neoplastic
subtypes. A study by Hricak et al3 found that the 2 most
signiﬁcant predictors of malignancy were the presence of vegetations in a
cystic lesion and the presence of necrosis in a solid lesion.14 Other
predictors of malignancy include wall or septal thickness >3 mm,
presence of ascites, and a maximum diameter greater than 4 to 6 cm
(Figure 14-17 On T2W images, an ovarian mass of high signal
intensity that is found in conjunction with implants in the abdomen and
pelvis is suggestive of mucinous cystadenocarcinoma with peritoneal
metastatic disease. Because of the inherent wide ﬁeld of view of MRI
relative to pelvic ultrasound, a single MRI examination can not only
characterize an ovarian mass but can also be used in staging when a mass
is noted to have malignant features. The presence of ascites,
peritoneal, or serosal metastases as well as hydronephrosis may be
Nonovarian adnexal masses
large ﬁeld of view also allows MRI to localize pelvic lesions and their
origin more accurately. Identiﬁcation of a pelvic mass separate from the
uterus and ovary changes the differential diagnosis. Examples of such
lesions that may be accurately diagnosed by MRI include peritoneal
inclusion cysts (Figure 7), pedunculated ﬁbroid cysts, para-ovarian
cysts, paratubal cysts, or lymphadenopathy. Cystic midline lesions that
are accurately characterized by MRI include Gartner’s duct cyst,
Bartholin’s cyst, and urethral diverticula (Figure 8).
anatomy is well delineated by MRI. The 3 distinct zones (which are most
clearly delineated on sagittal T2W images) are the outer myometrium
(intermediate-to-high signal), the inner myometrium or junctional zone
(low signal), and the endometrial complex (high ﬂuid/near ﬂuid signal).
Endometrial thickness varies greatly, depending on the phase of the
menstrual cycle and the age of the patient. It is generally<15 mm in
premenopausal women and <8 mm in postmenopausal women, regardless of
cycle or hormonal stimulation. The junctional zone appears as low signal
intensity on T2W images and typically measures <12 mm. The intrinsic
T2 contrast between the outer myometrium and the junctional zone
becomes less marked in the postmenopausal uterus because of reduced ﬂuid
in the tissues.
uterine neoplasms, are the most common tumor of the female genital
tract. Their classiﬁcation is based on their location within the uterine
corpus as either intramural, submucosal, or subserosal. Most women are
asymptomatic; however, the most common symptom is bleeding. Transvaginal
ultrasound has been shown to be as efﬁcient as MRI in the detection of
the presence of myomas; however, MRI is superior in terms of mapping
individual myomas.18 This is especially true with larger uteri and with the presence of a large number of myomas.
MRI, a uterus containing leiomyomas will be enlarged and will have an
abnormal contour. On T2W images, leiomyomas appear as sharply marginated
lesions of low signal intensity relative to the myometrium (Figure 9).
Often, a high-signal-intensity rim can be identiﬁed, more commonly in
intramural or subserosal leiomyomas. Leiomyomas may contain
calciﬁcations, especially in older women. Calciﬁed myomas can cause
signiﬁcant artifact on ultrasound and can obscure adjacent tissues.
While similar calciﬁcation appears as a signal void on MRI, it typically
does not limit the evaluation of adjacent tissues. On MRI, myomas
larger than 3 to 5 cm are often heterogeneous because of various degrees
of degeneration. Although varied, enhancement tends to be heterogeneous
and less than that of the myometrium.19-21
MRI is the modality of choice in evaluating leiomyomas before and after treatment with uterine artery embolization (UAE).20,21 The
use of MRI is optimal for pre-embolization assessment for delineating
the location of leiomyoma and for accurately assessing pedunculated
lesions. It is particularly useful in providing postembolization
comparative images to assess whether there are persistent enhancing
ﬁbroids and to compare pre- and posttherapeutic size. Pre-embolization
MRI may also be used to predict collateral feeding vessels by modifying
protocol to optimize angiographic imaging. MRI can also identify or
exclude the presence of other uterine abnormalities that may impact or
preclude treatment.22 Various studies have shown that certain
preprocedural imaging characteristics may accurately predict response
to UAE. High signal intensity on T1W sequences may indicate pre-existing
hemorrhagic infarction, resulting in poor outcome secondary to
insufﬁcient volume reduction. The degree of contrast enhancement has
been shown to correlate with tumor response. A complete lack of contrast
enhancement indicates nonviable tumor that will not respond to
treatment.22,23 After successful UAE, there is an overall
reduction in uterine size and in mean leiomyoma volume. MRI
characteristics that indicate a successful treatment include high signal
intensity on T1W images and homogenously decreased T2 signal intensity.
These ﬁndings are suggestive of hemorrhagic infarction and correlate
with a lack of contrast enhancement (Figure 10).22-24 This
lack of contrast enhancement has been shown to persist as far out as 3
years postembolization. Similarly, a lack of infarction at short-term
follow-up will likely persist at long-term follow-up with MRI.
is the presence of ectopic endometrial glands from the basal layer of
the endometrium within the myometrium, often associated with myometrial
hyperplasia. It is a common gynecologic disorder that most commonly
affects premenopausal women. Symptoms are nonspeciﬁc and include pelvic
pain, dysmenorrhea, menorrhagia, and abnormal uterine bleeding.25 Al-though
adenomyosis is typically a diffuse process, focal areas of involvement
are also seen. It is these focal lesions that are often mistaken for
leiomyomas. It is important to differentiate between them, as their
treatments vary greatly. Although gonadotropin-releasing hormone analog
therapy or endometrial ablation can be performed, the deﬁnitive
treatment for severe cases of adenomyosis is ultimately hysterectomy.
With the advent of more conservative therapies such as embolization
therapy, MRI may play a role in monitoring treatment response.26
Studies have shown that MRI is superior to ultrasound for the diagnosis of adenomyosis.26 The
characteristic appearance of adenomyosis on MRI is diffuse thickening
(>12 mm) of the junctional zone. This is most evident on T2W
sequences and corresponds to the smooth muscle hyperplasia associated
with the ectopic tissue. A junctional zone ≤8 mm virtually excludes the
disease, whereas a width of 9 to 11 mm is equivocal. Other ﬁndings that
may suggest the diagnosis include poorly deﬁned margins of the
junctional zone and foci of high signal intensity on T1W or T2W
sequences that indicate the presence of endometrial cysts (Figure 11).
The foci of high signal may represent ectopic endometrium, cystically
dilated endometrial glands, or hemorrhage.27-29 Contrast administration has been shown to be of very little beneﬁt in the diagnosis of adenomyosis.
between focal adenomyosis and leiomyomas is reliably achieved with MRI,
and we now know that these conditions often coexist.29 Unlike
leiomyomas, a focal area of adenomyosis will have indistinct margins
and extend subjacent to the myometrium. The signal characteristics will
otherwise be the same as with the diffuse form of the disease. Treatment
implications for focal adenomyosis and leiomyoma differ, however, so
accurate diagnosis is important.
Uterine endometrial pathology
Endometrial thickening seen at ultrasound is a nonspeciﬁc ﬁnding.30 For
years, endometrial biopsy was the diagnostic standard for
differentiating benign causes, such as polyps and leiomyomas, from
endometrial carcinoma. However, benign abnormalities far outnumber
cancer in these situations.30 Other problems with biopsy
include vaginal or cervical stenosis and difﬁculty in obtaining an
adequate specimen. MRI can be helpful in further differentiating these
typically present with postmenopausal bleeding, particularly in patients
on tamoxifen therapy. Transvaginal ultrasound has high sensitivity and
speciﬁcity for endometrial polyps.31,32 Sonohysterography is the most sensitive and speciﬁc imaging modality.
MRI, endometrial polyps are of intermediate signal intensity on T1W
images and of intermediate-to-high signal intensity on T2W images. Their
signal intensity on T2W images tends to be higher than that seen in
endometrial carcinoma. The presence of a central focus of low signal
intensity on T2W images indicates a ﬁbrous core, which suggests the
diagnosis of an endometrial polyp (Figure 12).33 They are also more likely than endometrial carcinoma to contain intramural cysts,32-34 which
appear as smooth-walled, well-deﬁned cystic structures of high signal
intensity on T2W images. However, these cysts may also be observed in
endometrial carcinoma. Utilizing contrast enhancement signiﬁcantly
improves lesion detection. However, enhancement patterns do not reliably
distinguish endometrial carcinoma from other lesions. Although these
imaging features can help distinguish polyps from endometrial carcinoma,
it is often not speciﬁc enough to avoid the need for biopsy. Moreover,
these 2 conditions frequently coexist.34,35
Endometrial carcinoma is the fourth most common cancer in women.36-39 The
disease occurs most commonly in women in the sixth and seventh decades
of life. Clinically, patients present with abnormal uterine bleeding in
75% to 90% of cases. As a result of the early clinical symptoms,
patients often present with early-stage disease.34
represents roughly 90% of endometrial carcinomas, with varying grades
of differentiation. Other histologic subtypes include squamous,
papillary, and clear-cell carcinoma. However, histology cannot be
determined based on imaging characteristics.38,39
is not recommended as a screening procedure in the diagnosis of
endometrial carcinoma. However, MRI has proven to be an important tool
for the staging of known endometrial carcinoma.38 MRI can
differentiate between superﬁcial and deep-muscle–invasive tumors by
using a combination of T2W imaging and contrast-enhanced MRI. This can
signiﬁcantly alter surgical management. The presence of cervical
invasion also alters preoperative and surgical management. MRI has been
shown to be superior to both CT and ultrasound in assessing myometrial
invasion, cervical extension, and nodal involvement.
carcinomas appear isointense to the myometrium and endometrium on T1W
images. On T2W images, their signal intensity is commonly hyperintense;
however, this is quite variable.38 Endometrial carcinomas
usually enhance less than the myometrium does, with the difference less
marked on delayed images. Myometrial invasion is best visualized on T2W
images, where it appears as a disruption or an irregularity of the
junctional zone by a mass of intermediate signal intensity (Figure 13).
extension of tumor is identiﬁed by interruption of the normal low
signal intensity of the serosal surface. However, early serosal invasion
may be difﬁcult to detect. Parametrial involvement is best depicted on
T1W images with a signal intensity change in the parametrial fat.
T1-weighted images are also better for identifying tumor involvement of
the vagina when there is disruption of the low signal intensity wall.
Lymph node involvement is suggested on T1W images with nodes that have a
diameter >1 cm in the short axis. MRI can also detect tumor
extension outside the true pelvis as well as bladder and rectal
Like the uterus, the
cervix has a zonal anatomy that is well delineated on T2W images.
Cervical cancer is the third most common gynecologic malignancy in
women. MRI is not initially used to diagnose cervical cancer but is used
to stage disease in women who have had a diagnosis established by a Pap
smear or biopsy. T2-weighted images obtained in the sagittal plane and
in a plane along the short axis of the cervix are the most useful for
local staging. On T2W images, cervical cancer appears as a mass of
higher signal intensity than the adjacent ﬁbrous cervical stroma, but
the mass is of lower signal intensity than the endometrium.33 If
the low signal intensity of the inner cervical stroma is preserved,
stage IIB or higher disease is excluded, which indicates that the
patient is likely a surgical candidate. Macroscopic extension of tumor
into the parametrial fat establishes a diagnosis of stage IIB disease.
MRI has an accuracy range of 75% to 95% in detecting parametrial
invasion (Figure 14). MRI can accurately assess for more advanced
disease such as pelvic sidewall invasion and obstruction of the distal
ureter.33 Localizing the tumor and determining the presence
or absence of ureteral obstruction can provide a road map for radiation
Dynamic MRI of the pelvic ﬂoor
dysfunction annually affects nearly 300,000 to 400,000 women severely
enough to necessitate surgery. Dysfunction of the pelvic ﬂoor may
manifest as prolapse, incontinence, pelvic pain, or constipation.40
pelvic ﬂoor can be divided into 3 compartments: the anterior
compartment, which contains the bladder and urethra; the middle
compartment, which contains the vagina, cervix, and uterus; and the
posterior compartment, which contains the rectum. All 3 compartments are
supported by a complex network of muscles and fascia that form the
urogenital diaphragm, or the pelvic ﬂoor. Damage to ≥1 of these
myofascial elements can lead to individual or multiple organ prolapse,
and overall laxity and stretching or tearing can lead to generalized
pelvic ﬂoor relaxation.
Diagnosis and grading of pelvic ﬂoor
dysfunction has previously been performed with physical examination and
radiographic imaging, such as voiding cystourethrography, evacuation
proctography, cystocolpoproctography, and peritoneography. However, the
development of fast MRI sequences has allowed for the quick evaluation
of pelvic organ prolapse and pelvic ﬂoor relaxation with increased
patient comfort, decreased complexity, and decreased invasiveness and
radiation exposure.41 The intrinsic soft tissue contrast
capability of MRI allows for detailed visualization of the pelvic ﬂoor,
and the faster techniques now allow for dynamic evaluation of pelvic
support structures. Studies have shown that dynamic MRI has greater
sensitivity than physical examination and has led to changes in the
initial surgical plan in 41% of patients. It has become clear that MRI
has an important role in the preoperative planning in patients with
pelvic ﬂoor dysfunction.42,43
universally accepted radiologic criteria for assessing pelvic ﬂoor
dysfunction exist; however, the most widely accepted criteria involve
organ movement below the pubococcygeal line (PCL), which extends from
the inferior margin of the symphysis pubis to midway between the ﬁrst
and second coccygeal segments. A line that extends from the lowermost
aspect of the symphysis pubis to the puborectalis muscle forms the
puborectalis hiatus. In the normal patient, the puborectalis hiatus is
<6 cm and does not descend >2 cm below the PCL. The upper urethra,
urethrovesical junction, bladder, upper vagina, uterus, small bowel,
sigmoid colon, mesenteric fat, and rectum should all be above the
hiatus. Staging of any prolapse is done in 2-cm increments below the
puborectalis hiatus. Small is 0 to 2 cm below, moderate is 2 to 4 cm,
and a large prolapse extends >4 cm below this line.
optimal MRI evaluation in the sagittal plane, the patient is placed in
the supine position. Static images are ﬁrst obtained, with subsequent
series of images performed during resting and straining in the
midsagittal plane. Selected midline sagittal T2W images at rest and on
the Valsalva maneuver and/or sagittal 2D GRE images in real-time at rest
and on Valsalva are used to assess the degree of pelvic ﬂoor descent
and pelvic organ prolapse (Figure 15).42,43 Some authors advocate the use of intraluminal contrast, but this is not used routinely at our institution.
Müllerian duct anomalies
incidence of müllerian duct anomalies is approximately 0.1% to 3%.
Although they are often asymptomatic, obstetrical complications occur in
up to 25% of these women, including spontaneous abortion, stillbirth,
preterm delivery, and adverse obstetrical outcomes. Knowledge of the
type and severity of the anomaly can signiﬁcantly impact treatment, as
the therapies vary greatly. With an accuracy approaching 100%, MRI has
become the gold standard in identifying müllerian duct anomalies.44-47 Various studies have shown that it is superior to sonography and hysterosalpingography.46 In patients with primary amenorrhea, MRI can determine the presence or absence of the vagina, cervix, and uterus.47 Bicornuate
and septate uteri are the 2 most common types of müllerian ductal
anomalies. Differentiating between these 2 entities is important because
of their complications and different treatments. The evaluation of the
external fundal contour is the key to differentiating between bicornuate
and septate uteri (Figure 16). This can be best evaluated on a plane
that passes through the long axis of the uterus. The outer contour of
the septated uterus is convex or ﬂat, with <10-mm concavity. The
outer fundal contour of a bicornuate uterus or uterus didelphys should
have >10-mm concavity between the right and left uterine horns.
remains the ﬁrst line of imaging for the female pelvis, with high
diagnostic accuracy rates for uterine and ovarian abnormalities. MRI
should be considered for the evaluation of adnexal pathology when
sonographic characteristics are not deﬁnitive to determine whether an
adnexal mass is ovarian in origin and to determine the likelihood of
malignancy. MRI has an established role in the pre- and post-procedural
assessment for uterine artery embolization, diagnosis of adenomyosis,
staging of known endometrial and cervical carcinoma, evaluation of
suspected müllerian ductal anomalies, and presurgical workup for pelvic
ﬂoor prolapse. Other indications not discussed here include assessment
of the pregnant patient with acute pelvic pain and of fetal anatomy. In
most cases, fetal anatomy is well evaluated by ultrasound, but MRI can
play a role in problem solving. For the acute pelvis and when there is a
concern for acute appendicitis, the role of MRI has yet to be
established. Beyond the period of organogenesis, CT may be considered.
Within the period of organogenesis, however, MRI is a safe alternative,
and limited studies to date have shown promising results.
- ACR Practice Guideline for the Performance of Pelvic Ultrasound in Females. Reston, VA: American College of Radiology;2006.
Practice Guideline for the Performance of Magnetic Resonance Imaging
(MRI) of the Soft Tissue Components of the Pelvis. Reston, VA: American
College of Radiology;Amended 2006.
- Hricak H, Chen M, Coakley F,
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LB, Panageas E, Lange R, et al. Female pelvis: Impact of MR imaging on
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- Outwater EK, Mitchell DG. Normal ovaries and functional cysts: MR appearance. Radiology. 1996;198:397-402.
CL, Ueland FR, Land GL, et al. The malignant potential of cystic
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- Togashi K, Nishimura K, Kimura I, et al. Endometrial cysts: Diagnosis with MR imaging.Radiology.1991;180:73-78.
- Kimura I, Togashi K, Itoh K, et al. Ovarian torsion: CT and MR imaging appearances. Radiology. 1994; 190:337-341.
- Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: Tumor types and imaging characteristics. RadioGraphics. 2001;21:475-490.
V, Guerriero S, Ajossa S, et al. Transvaginal ultrasonography in the
diagnosis of cystic teratoma. Obstet Gynecol. 1995;85:48-52.
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