DOI:10.2214/AJR.06.1196
AJR 2007; 188:1577-1587
© American Roentgen Ray Society
MRI of Malignant Neoplasms of the Uterine Corpus and Cervix
Evis Sala1,
Suzanne Wakely,
Emma Senior and
David Lomas
1 All authors: Department of Radiology, Addenbrooke's Hospital, University of
Cambridge, Hills Rd., Cambridge CB2 2QQ, United Kingdom.
Received September 7, 2006;
accepted after revision January 26, 2007.
Address correspondence to E. Sala
(es220{at}radiol.cam.ac.uk).
CME
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FOR YOUR INFORMATION
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Abstract
OBJECTIVE. In this article, we review the role of MRI in the imaging
of malignant neoplasms of the uterine corpus and cervix, describing its role
in staging, treatment planning, and follow-up.
CONCLUSION. MRI is not officially incorporated in the International
Federation of Gynecology and Obstetrics (FIGO) staging system, but is already
widely accepted as the most reliable imaging technique for the diagnosis,
staging, treatment planning, and follow-up of both endometrial and cervical
cancer. MRI protocols need to be optimized to obtain the best results and
avoid pitfalls.
Keywords: dynamic MRI • genitourinary tract imaging • gynecologic oncology • MRI • oncologic imaging • women's imaging
Introduction
The role of MRI in gynecologic oncology has evolved during the past two
decades. There is now a substantial body of evidence that MRI is useful in
evaluating malignant conditions of the pelvis
[1,
2]. MRI has been shown to be
superior to CT in staging of endometrial and cervical carcinoma. In addition,
there is evidence that MRI may aid in differentiating radiation fibrosis from
recurrent tumor [3]. The
accuracy of MRI assessment of lymph nodes is similar to that of CT; both rely
on size criteria to detect the presence of metastases
[4]. However, more recently,
lymph node–specific contrast agents have emerged as useful tools for
determining the presence of metastases in the lymph nodes
[5].
MRI has been shown to minimize costs in some clinical settings by limiting
or eliminating the need for further expensive or more invasive diagnostic or
surgical procedures [6,
7]. In this article, we review
the role of MRI in staging, treatment planning, and follow-up of malignant
neoplasms of the uterine corpus and cervix.
Malignant Neoplasms of the Uterine Corpus
Adenocarcinomas arise from the uterine epithelium and constitute 90% of
endometrial cancers. The remaining histologic types of endometrial carcinoma
include adenocarcinoma with squamous differentiation, adenosquamous carcinoma,
clear cell carcinoma, and papillary serous carcinoma. Uterine sarcomas are
rare tumors of mesenchymal origin accounting for 2–6% of all uterine
malignant tumors [8]. The most
common histologic variants are endometrial stromal sarcoma, mixed
müllerian tumors, and leiomyosarcoma. Primary uterine lymphoma is very
rare, occurring in only 1% of patients with lymphoma. Metastases to the uterus
from nongynecologic neoplasms are rare, with breast and the gastrointestinal
tract being the two most common primary sites.
Endometrial Carcinoma
Endometrial carcinoma is the fourth most common female cancer and the most
common malignancy of the female reproductive tract
[9]. In 2007, 39,080 new cases
and 7,400 deaths are expected in the United States
[9]. The incidence is rising
because of increased life expectancy and obesity. Five-year survival rates
vary between 96% for stage I disease and 25% for stage IV disease
[9]. The prognosis of women
with endometrial carcinoma depends on a number of factors, including stage,
depth of myometrial invasion, lymphovascular invasion, nodal status, and
histologic grade [10].
Preoperative evaluation of these prognostic factors helps in subspecialist
treatment planning [11].
MRI Protocol
Imaging technique and patient preparation are important to obtain optimal
results. Patients are usually instructed to fast for 4–6 hours before
the MRI examination to limit artifact due to small-bowel peristalsis. An
anti-peristaltic agent (hyoscine butyl bromide or glucagons) may be
administered to the patient before imaging as an alternative to fasting.
Ideally, the patient is asked to empty the bladder before going on the MR
scanner. A full bladder may degrade T2-weighted images because of ghosting and
motion artifacts. Patients are imaged in the supine position using a pelvic
surface array multichannel coil.
The basic MRI protocol (Table
1) includes axial T1-weighted spin-echo images with a large field
of view to evaluate the entire pelvis and upper abdomen for lymphadenopathy
and bone marrow changes; high-resolution T2-weighted fast spin-echo (FSE)
images in the axial and sagittal planes for the evaluation of the primary
tumor; and dynamic contrast-enhanced T1-weighted images (small field of view)
in the sagittal and axial oblique planes to evaluate the extent of myometrial
and cervical involvement.
High-resolution T2-weighted FSE sequences perpendicular to the long axis of
the uterine corpus are favored for the evaluation of primary tumor and
myometrial invasion [12].
Sagittal and oblique axial multiphase IV contrast–enhanced 3D
T1-weighted fat-saturated sequences through the uterine corpus are routinely
used to improve staging accuracy. The early enhancement phases (0 and 1
minute) allow identification of the subendometrial zone, which enhances
earlier than the bulk of the myometrium and corresponds to the inner
junctional zone. Identification of this zone is especially important in
detecting early myometrial invasion because the junctional zone often becomes
indistinct in post-menopausal women
[13]. The equilibrium phase
(2–3 minutes after injection) allows better evaluation of deep
myometrial invasion [14],
whereas the delayed phase (4–5 minutes) enables better evaluation of
cervical stroma invasion [15].
The tumor–myometrium interface should be assessed in at least two
planes.
The Impact of Imaging on Treatment
Endometrial cancer primarily presents at stage I (80% of cases), and the
standard treatment is total abdominal hysterectomy and bilateral
salpingo-oophorectomy. The clinical challenge is to effectively select
patients at risk of relapse for more radical surgery (i.e., radical lymph node
resection) and adjuvant treatment and to avoid overtreating low-risk patients.
Furthermore, the recent introduction of laparoscopic techniques offers an
alternative approach for patients who present with early disease
[16,
17].
The major diagnostic factor necessary for the preoperative evaluation of
endometrial cancer is to differentiate between stages IA and IB; this is
becoming critical with increased use of hormonal treatment for stage IA
disease in patients at high-risk for perioperative morbidity.
The risk of lymph node metastasis must be determined to select the
appropriate surgical management. Differentiation of stage IB from stage IC has
prognostic and morbidity implications. Stage IB patients should undergo lymph
node sampling, whereas stage IC patients should undergo radical lymph node
resection.
Gross cervical invasion requires preoperative radiation therapy or a
different surgical plan—that is, radical hysterectomy instead of total
abdominal hysterectomy.
Surgical staging of endometrial carcinoma is intended as the initial
treatment and, at the same time, is used to identify patients who may require
adjuvant therapy. The depth of myometrial invasion is probably the single most
important morphologic prognostic factor because it correlates with tumor
grade, tumor extension into the cervix, and the prevalence of lymph node
metastases [18,
19]. The incidence of lymph
node metastases (pelvic, paraaortic, or both) increases from 3% with
superficial myometrial invasion (stage IB) to 46% with deep myometrial
invasion (stage IC)
[19–21].
Evaluation of the extent of myometrial invasion by gross inspection at surgery
or at frozen-section analysis remains inaccurate in a significant proportion
of patients [22,
23].
Controversy regarding the role of lymphadenectomy still exists, and
practices vary considerably
[24,
25]. Indications for
lymphadenectomy include grade 1 or 2 tumors with deep myometrial invasion; all
grade 3 tumors; cervical stroma invasion; and high-risk histologic subtypes,
such as serous papillary and clear cell
[25]. Lymphadenectomy carries
a high risk of complications and careful selection of high-risk patients is
crucial for specialist surgical referral to a gynecologic oncology team
[11].
In summary, MRI may assist in the preoperative assessment and surgical
planning by accurately predicting the depth of myometrial invasion, cervical
stroma invasion, lymph node involvement, and metastatic spread. MRI can also
provide additional useful information such as uterine size, tumor volume, and
ascites, and can reveal adnexal abnormalities that in turn may determine the
surgical approach (i.e., transabdominal vs transvaginal vs laparoscopic). In
high-risk patients due to comorbidity, MRI is useful in planning nonsurgical
treatment options such as radiation therapy or hormonal therapy (stage
IA).
Diagnosis
Endometrial carcinomas are typically diagnosed at endometrial biopsy or
dilatation and curettage, with MRI being reserved to evaluate the extent of
disease. MRI is the most accurate imaging technique for the preoperative
assessment of endometrial cancer because of its superb soft-tissue contrast
resolution. The routine use of dynamic IV contrast enhancement is necessary
for state-of-the-art MR evaluation of endometrial carcinoma
[11,
13,
14,
26–29].
On unenhanced T1-weighted images, endometrial carcinoma is isointense to
the normal endometrium. Although endometrial cancer may show high signal
intensity on T2-weighted sequences, it is more typically heterogeneous and may
even be of low signal intensity. After IV contrast medium administration, the
normal inner myometrium shows avid enhancement earlier than the outer
myometrium [13,
27,
28]. The maximum contrast
between the inner and outer layers of the myometrium occurs at 50 seconds
[28]. In general, endometrial
cancer enhances earlier than normal endometrium but later than the adjacent
myometrium, allowing identification of small tumors, even those contained by
the endometrium. The maximum tumor–myometrium contrast occurs during the
equilibrium phase [14].
Staging
Imaging criteria for staging of endometrial cancer are based on the TNM or
International Federation of Gynecology and Obstetrics (FIGO) classification
system (Table 2). However, the
FIGO staging system is based on surgical and pathologic findings alone, and
imaging, although useful in the preoperative assessment of tumor stage, is not
recognized as a method to be used for definitive staging.
MRI is significantly superior to sonography and CT in the evaluation of
both tumor extensions into the cervix and myometrial invasion
[30,
31]. The overall staging
accuracy of MRI has been reported to be between 85% and 93%
[13,
14,
26–30,
32,
33]. The routine use of
dynamic IV contrast enhancement significantly improves the accuracy of the
assessment of depth of myometrial invasion (accuracy of 55–77% for
T2-weighted images vs 85–91% for dynamic contrast-enhanced images)
[13,
14,
27,
29,
34].
Stage I—Stage I endometrial cancers include tumors confined
to the uterine corpus. Stage IA tumors (limited to the endometrium) appear as
normal or widened (focal or diffuse) endometrium. An intact junctional zone
and a band of early subendometrial enhancement exclude deep myometrial
invasion [13,
27] (Fig.
1A,
1B). Regardless of the MR
sequence, the tumor–myometrium interface appears smooth and sharp. In
stage IB disease (Fig. 2A,
2B), tumor extends less than
50% into the myometrium with associated disruption or irregularity of the
junctional zone and a band of early subendometrial enhancement. If these
landmarks are not present, stage IB tumor is suggested by an irregular
tumor–myometrium interface. The presence of low-signal-intensity tumor
during the equilibrium phase within the outer myometrium indicates deep
myometrial invasion—that is, stage IC disease.
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Fig. 1A —Stage IA endometrial carcinoma in 64-year-old woman. Sagittal
T2-weighted fast spin-echo (A) and early phase (60 seconds)
gadolinium-enhanced fat-suppressed T1-weighted (B) MR images show
endometrial carcinoma (T) confined to endometrium. Zonal anatomy
(arrows in A) is indistinct on T2-weighted image. However,
intact band of early subendometrial enhancement seen on T1-weighted image
(arrows in B) excludes myometrial invasion.
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Fig. 1B —Stage IA endometrial carcinoma in 64-year-old woman. Sagittal
T2-weighted fast spin-echo (A) and early phase (60 seconds)
gadolinium-enhanced fat-suppressed T1-weighted (B) MR images show
endometrial carcinoma (T) confined to endometrium. Zonal anatomy
(arrows in A) is indistinct on T2-weighted image. However,
intact band of early subendometrial enhancement seen on T1-weighted image
(arrows in B) excludes myometrial invasion.
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Fig. 2A —Stage IB endometrial carcinoma in 65-year-old woman. Sagittal
T2-weighted fast spin-echo (A) and gadolinium-enhanced fat-suppressed
T1-weighted (B) MR images show endometrial carcinoma (T) with
superficial myometrial invasion. Note disruption of junctional zone
(arrow in A). Tumor involves less than 50% of myometrium
(arrow in B), which is better shown on T1-weighted image.
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Fig. 2B —Stage IB endometrial carcinoma in 65-year-old woman. Sagittal
T2-weighted fast spin-echo (A) and gadolinium-enhanced fat-suppressed
T1-weighted (B) MR images show endometrial carcinoma (T) with
superficial myometrial invasion. Note disruption of junctional zone
(arrow in A). Tumor involves less than 50% of myometrium
(arrow in B), which is better shown on T1-weighted image.
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The sensitivity and specificity of MRI in the assessment of the depth of
myometrial invasion range from 69% to 94% and from 64% to 100%, respectively
[13,
14,
27,
29,
34]. An erroneous MRI
assessment of the depth of myometrial invasion may occur when assessing a
large polypoid endometrial carcinoma that distends the uterus so that the thin
rim of myometrium is stretched over the carcinoma rather than showing deep
infiltration [13,
21,
35]. Other causes include
coexistent benign abnormalities (e.g., leiomyomas, adenomyosis)
[15,
32,
35], congenital anomalies,
indistinct zonal anatomy [15],
poor tumor–myometrium contrast
[15,
21,
29,
36–38],
and tumor extension to the uterine cornu
(Table 3).
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TABLE 3: Classification of Endometrial Carcinoma Using TNM and International
Federation of Gynecology and Obstetrics (FIGO) Staging Systems
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Stage II—Stage II includes tumor extension beyond the
uterine corpus into the cervix. In stage IIA, invasion of the endocervix
appears as widening of the internal os and endocervical canal with
preservation of the normal low-signal-intensity fibrocervical stroma (Fig.
3A,
3B).
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Fig. 3A —Stage IIA endometrial carcinoma in 78-year-old woman.
Sagittal T2-weighted fast spin-echo (A) and gadolinium-enhanced
fat-suppressed T1-weighted (B) MR images show endometrial carcinoma (T)
with deep myometrial invasion and tumor extension into cervical canal
(arrow in A). Note preservation of low-signal-intensity
cervical stroma (asterisks). Normal enhancement of cervical mucosa
(arrow in B) on enhanced images excludes cervical stroma
invasion. Incidental presence of uterine leiomyoma (L) is noted.
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Fig. 3B —Stage IIA endometrial carcinoma in 78-year-old woman.
Sagittal T2-weighted fast spin-echo (A) and gadolinium-enhanced
fat-suppressed T1-weighted (B) MR images show endometrial carcinoma (T)
with deep myometrial invasion and tumor extension into cervical canal
(arrow in A). Note preservation of low-signal-intensity
cervical stroma (asterisks). Normal enhancement of cervical mucosa
(arrow in B) on enhanced images excludes cervical stroma
invasion. Incidental presence of uterine leiomyoma (L) is noted.
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Disruption of the fibrocervical stroma by high-signal-intensity tumor on
T2-weighted images indicates cervical stroma invasion—stage IIB disease.
Focal disruption of normal enhancement of the cervical mucosa by
low-signal-intensity tumor on late dynamic contrast-enhanced MRI is useful in
distinguishing cervical stroma invasion from polypoid tumor protruding from
the endometrial cavity into the endocervix.
The accuracy of MRI in detecting cervical invasion reaches 92%, with
sensitivities of 75–80% and specificities of 94–96%
[14,
39].
Stage III—In stage III disease, tumor extends outside the
uterus but not outside the true pelvis. Parametrial involvement—stage
IIIA—appears as disruption of the serosa with direct extension into the
surrounding parametrial fat. In stage IIIB disease, tumor extends into the
upper vagina, and there is segmental loss of the low-signal-intensity vaginal
wall. In stage IIIC disease, lymphadenopathy is present.
Stage IV—Stage IV disease is tumor that extends beyond the
true pelvis or invades the bladder or rectum. The loss of low signal intensity
of the bladder or rectal wall indicates stage IVA disease
[15]. In stage IVB disease,
there is distant metastasis, malignant ascites, or peritoneal deposits.
Peritoneal deposits are better seen on delayed dynamic contrast-enhanced MRI
[40].
Uterine Sarcomas (Leiomyosarcomas, Endometrial Sarcomas, Malignant Mixed Müllerian Tumors)
Sarcomas of the uterus are often highly malignant. They are rare, with an
incidence of approximately 2 per 100,000 women over the age of 20 years, and
account for 3–5% of all uterine cancers. The tumors are frequently large
at the time of the examination, and it is difficult to determine the primary
origin of the mass. MRI can provide an accurate preoperative assessment of
uterine size and degree of involvement. The MRI features are nonspecific and
may be indistinguishable from those of endometrial carcinoma
[8,
41,
42]. However, uterine sarcomas
tend to be large and heterogeneous with areas of hemorrhage and cystic
necrosis. Deep myometrial invasion and peritoneal seeding are usually seen at
presentation (Fig. 4A,
4B,
4C).
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Fig. 4A —Malignant mixed müllerian tumor in 55-year-old woman.
Sagittal T2-weighted fast spin-echo (FSE) (A), sagittal
gadolinium-enhanced fat-suppressed T1-weighted (B), and axial oblique
T2-weighted FSE (C) images show large heterogeneous mass (T) that
contains areas of cystic necrosis. Tumor involves entire depth of myometrium
and invades cervical stroma (asterisks in A and B).
Note presence of enlarged bilateral obturator lymph nodes (N in C) and
associated left-side hydronephrosis (arrow in C).
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Fig. 4B —Malignant mixed müllerian tumor in 55-year-old woman.
Sagittal T2-weighted fast spin-echo (FSE) (A), sagittal
gadolinium-enhanced fat-suppressed T1-weighted (B), and axial oblique
T2-weighted FSE (C) images show large heterogeneous mass (T) that
contains areas of cystic necrosis. Tumor involves entire depth of myometrium
and invades cervical stroma (asterisks in A and B).
Note presence of enlarged bilateral obturator lymph nodes (N in C) and
associated left-side hydronephrosis (arrow in C).
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Fig. 4C —Malignant mixed müllerian tumor in 55-year-old woman.
Sagittal T2-weighted fast spin-echo (FSE) (A), sagittal
gadolinium-enhanced fat-suppressed T1-weighted (B), and axial oblique
T2-weighted FSE (C) images show large heterogeneous mass (T) that
contains areas of cystic necrosis. Tumor involves entire depth of myometrium
and invades cervical stroma (asterisks in A and B).
Note presence of enlarged bilateral obturator lymph nodes (N in C) and
associated left-side hydronephrosis (arrow in C).
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Leiomyosarcomas account for only 1.3% of uterine malignancies. Most
leiomyosarcomas arise de novo from the myometrium, although malignant
transformation of leiomyomas can occur. It has been suggested that an
irregular margin of uterine leiomyoma may indicate malignant transformation
[8,
43], but MRI cannot reliably
differentiate between a leiomyoma undergoing benign degeneration and a
leiomyosarcoma.
MRI of Malignant Neoplasms of the Uterine Cervix
The most common histologic type of cervical carcinoma is squamous cell
carcinoma (90%) followed by adenocarcinoma (5–10%). Other rare
histologic types include small-cell carcinoma, adenosquamous carcinoma, and
lymphoma. MRI features of these rare tumors are the same as those of squamous
cell carcinoma [44]. However,
small-cell carcinoma usually shows highly aggressive features, such as
parametrial involvement, pelvic lymphadenopathy, and distant metastasis
[44].
Carcinoma of the Cervix
Cervical carcinoma is the third most common gynecologic malignancy
[9]. In 2007, 11,150 new cases
and 3,670 deaths are expected in the United States
[9]. Five-year survival rates
vary between 92% for stage I disease and 17% for stage IV disease
[9]. During the past 50 years,
there has been a steep decline in the number of deaths from cervical cancer.
This improvement in mortality has been attributed to the development of the
Papanicolaou test; only minor improvement has been achieved in the survival of
invasive cervical cancer.
MRI Protocol
Patient preparation and coil choice for cervical cancer evaluation are
similar to that for endometrial carcinoma. Although a body coil has been shown
to provide similar staging accuracy, the use of a phased-array coil increases
resolution and decreases imaging time
[45,
46]. A basic imaging protocol
should include axial T1-weighted spin-echo images with a large field of view
and T2-weighted FSE images in the axial and sagittal planes with a small field
of view (Table 1).
Cervical tumors are best seen on T2-weighted images. The sagittal plane
allows evaluation of tumor extension into the body of the uterus and vagina.
The axial oblique T2-weighted FSE sequence perpendicular to the long axis of
the cervix is important in assessing parametrial invasion
[47]. Axial T2-weighted FSE
imaging with fat saturation can be helpful in the evaluation of parametrial
invasion, especially in younger women who have a prominent pericervical or
vaginal plexus. Axial TI-weighted images of the abdomen are also included to
identify enlarged abdominal lymph nodes.
The use of contrast medium is not necessary for cervical cancer
examinations because it does not improve staging accuracy compared with
unenhanced T2-weighted images
[48,
49]. However, dynamic
contrast-enhanced MRI may help distinguish recurrent tumor from postsurgical
changes [3].
Impact of Imaging on Treatment
Staging of cervical cancer is still based on clinical FIGO criteria
that—compared with surgical staging—can be erroneous in up to 32%
of patients with stage IB disease and up to 65% of patients with stage III
disease [50,
51]. The greatest difficulties
in the clinical evaluation of patients with cervical cancer are the assessment
of parametrial and pelvic sidewall invasion; accurate estimation of tumor
size, especially if the tumor is primarily endocervical in location; and
evaluation of lymph node metastases
[52,
53]. Accurate pretreatment
evaluation of these prognostic factors is crucial in determining appropriate
therapy in patients with cervical cancer.
The most important issue in staging of cervical cancer is to distinguish
early disease (stages I and IIA) that can be treated with surgery from
advanced disease (stage IIB or greater) that must be treated with radiation
alone or combined with chemotherapy. MRI is the best single imaging
investigation that can accurately determine tumor location (exophytic or
endocervical), tumor size, depth of stromal invasion, and extension into the
lower uterine segment [44,
54–56].
MRI is accurate for evaluation of tumor size, usually within 0.5 cm of the
surgical size, in 70–90% of cases
[57–59].
Finally, MRI is useful in the evaluation of lymph node metastases
[5].
Diagnosis
MRI is recommended for evaluating patients with clinical stage IB disease
or greater when the primary lesion is larger than 2 cm
[44,
54,
55] because of a relatively
high likelihood of parametrial invasion and lymph node metastases. Other MRI
indications include evaluation of pregnant patients and patients with
endocervical lesions [56].
On T1-weighted images, tumors are usually isointense to the normal cervix
and may not be visible. On T2-weighted images, cervical cancer appears as a
relatively hyperintense mass and is easily distinguishable from
low-signal-intensity cervical stroma. On dynamic contrast-enhanced MRI, small
tumors enhance homogeneously and earlier than the normal cervical stroma.
Large tumors are frequently necrotic and may or may not enhance, but are often
surrounded by an enhancing rim that facilitates tumor definition
[60,
61].
Staging
The recommendations for diagnostic evaluation of tumor staging derive from
the TNM and FIGO clinical staging systems
(Table 4). In
single-institution studies, MRI has been shown to be better than either CT or
physical examination in depicting parametrial invasion
[7,
62,
63]. The staging accuracy of
MRI ranges from 75% to 96%
[57–59,
62–65].
A recent prospective multi-center study conducted jointly by the American
College of Radiology Imaging Network (ACRIN) and the Gynecologic Oncology
Group (GOG) compared MRI, CT, and FIGO clinical staging in the pretreatment
assessment of early invasive cervical cancer
[66]. The study showed that
MRI was equivalent to CT for overall preoperative staging. However, MRI
performed significantly better than CT for preoperative tumor visualization
and determination of parametrial invasion. Reviewer agreement was higher for
MRI reviewers than for CT reviewers
[66].
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TABLE 4: Classification of Cervical Carcinoma Using TNM and International
Federation of Gynecology and Obstetrics (FIGO) Staging Systems
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Fig. 5A —Stage IIB cervical cancer in 47-year-old woman. Sagittal fast
spin-echo (A) and axial fat-suppressed (B) T2-weighted images
show small cervical cancer (T) involving anterior lip of cervix. Tumor invades
fibrocervical stroma on left as shown by focal disruption of
low-signal-intensity ring (arrow in B). Pathology showed
full-depth stromal invasion with tumor extending 2 mm into left
parametrium.
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Fig. 5B —Stage IIB cervical cancer in 47-year-old woman. Sagittal fast
spin-echo (A) and axial fat-suppressed (B) T2-weighted images
show small cervical cancer (T) involving anterior lip of cervix. Tumor invades
fibrocervical stroma on left as shown by focal disruption of
low-signal-intensity ring (arrow in B). Pathology showed
full-depth stromal invasion with tumor extending 2 mm into left
parametrium.
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Fig. 6A —Stage IIB cervical cancer in 42-year-old woman. Sagittal fast
spin-echo (A), axial oblique (B), and coronal oblique (C)
T2-weighted images show cervical cancer (T) involving both anterior and
posterior lips of cervix. Tumor invades fibrocervical stroma bilaterally, as
shown by loss of low-signal-intensity ring, and extends to both parametria
(arrows in B). Coronal oblique image shows bilateral
parametrial invasion (arrows in C) and enlarged lymph nodes (N
in C).
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Fig. 6B —Stage IIB cervical cancer in 42-year-old woman. Sagittal fast
spin-echo (A), axial oblique (B), and coronal oblique (C)
T2-weighted images show cervical cancer (T) involving both anterior and
posterior lips of cervix. Tumor invades fibrocervical stroma bilaterally, as
shown by loss of low-signal-intensity ring, and extends to both parametria
(arrows in B). Coronal oblique image shows bilateral
parametrial invasion (arrows in C) and enlarged lymph nodes (N
in C).
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Fig. 6C —Stage IIB cervical cancer in 42-year-old woman. Sagittal fast
spin-echo (A), axial oblique (B), and coronal oblique (C)
T2-weighted images show cervical cancer (T) involving both anterior and
posterior lips of cervix. Tumor invades fibrocervical stroma bilaterally, as
shown by loss of low-signal-intensity ring, and extends to both parametria
(arrows in B). Coronal oblique image shows bilateral
parametrial invasion (arrows in C) and enlarged lymph nodes (N
in C).
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Stage I—Stage I tumors are confined to the uterus. Stage IA
is defined as a microinvasive tumor that cannot be reliably shown on
T2-weighted images. However, microinvasive disease may be detected on dynamic
MRI as a strongly enhancing area on early arterial phase images
[60]. The accuracy in
differentiating deep (> 3 mm) from superficial invasion has been reported
to be 76%, 98%, and 63% on T2-weighted images, dynamic contrast-enhanced
images, and contrast-enhanced T1-weighted images, respectively
[60]. Stage IB carcinoma
appears as a high-signal-intensity mass in contrast to the
low-signal-intensity fibrocervical stroma seen on T2-weighted images.
Young women with stage IA or small stage IB tumors who wish to retain their
fertility are considered for trachelectomy, an operation that excises the
cervix but preserves the uterine body and maintains fertility. MRI is accurate
for predicting myometrial invasion by tumor and in showing the relationship of
cervical carcinoma to the internal os with a sensitivity of 100% and
specificity of 96% [67].
Stage II—In stage IIA tumors, segmental disruption of the
upper two thirds of the vaginal wall without parametrial invasion is shown on
T2-weighted images. Cervical stroma invasion (Fig.
5A,
5B) and tumor extension into
the parametria are defined as stage IIB disease. The reported sensitivity of
MRI in the evaluation of parametrial invasion is 69%, and the specificity is
93%
[57–59,
62–65].
An intact low-signal-intensity cervical stroma virtually excludes parametrial
invasion with a negative predictive value of 94–100%
[56]. Segmental disruption of
the hypointense cervical stroma usually indicates full-thickness stromal
invasion. However, additional features, such as a spiculated
tumor–parametrium interface, soft-tissue extension into the parametria
(Fig. 6A,
6B,
6C), or encasement of the
periuterine vessels, are required to make a confident diagnosis of established
parametrial invasion [56].
An important pitfall of MRI staging is overestimation of parametrial
invasion on T2-weighted images in large tumors (accuracy of 70%) compared with
small ones (accuracy of 96%) due to stromal edema caused by tumor compression
or inflammation [56]
(Table 3). This pitfall may
lead to a higher rate of false-positive assessment of parametrial invasion in
patients with large tumors, which must be considered when making the treatment
decisions in these patients.
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Fig. 7A —Stage IVB cervical cancer in 39-year-old woman. Sagittal fast
spin-echo (A) and axial fat-suppressed (B and C)
T2-weighted images show large cervical cancer (T in A and B)
involving anterior lip of cervix. Tumor also invades posterior wall of
bladder, entire vagina, and urethra (asterisk in C).
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Fig. 7B —Stage IVB cervical cancer in 39-year-old woman. Sagittal fast
spin-echo (A) and axial fat-suppressed (B and C)
T2-weighted images show large cervical cancer (T in A and B)
involving anterior lip of cervix. Tumor also invades posterior wall of
bladder, entire vagina, and urethra (asterisk in C).
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Fig. 7C —Stage IVB cervical cancer in 39-year-old woman. Sagittal fast
spin-echo (A) and axial fat-suppressed (B and C)
T2-weighted images show large cervical cancer (T in A and B)
involving anterior lip of cervix. Tumor also invades posterior wall of
bladder, entire vagina, and urethra (asterisk in C).
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Stage III—In stage IIIA, vaginal involvement reaches the
lower one third of the vaginal canal without extending to the pelvic sidewall.
When the tumor extends to the pelvic sidewall (i.e., the pelvic musculature or
iliac vessels) or causes hydronephrosis, it is defined as stage IIIB.
Stage IV—Once tumor invades the adjacent organs, such as the
bladder and rectal mucosa, or distant metastasis occurs, the stage is defined
as IV (Fig. 7A,
7B,
7C). MRI findings suggesting
bladder invasion include focal or diffuse disruption of the normal
low-signal-intensity posterior bladder wall, nodular or irregular bladder
wall, mass protruding into the lumen of the bladder, or presence of bullous
edema. Rectal invasion is rare and appears as segmental thickening and loss of
the anterior rectal wall. Prominent strands between the tumor and the rectal
wall may also indicate rectal invasion.
The reported sensitivity of MRI in the evaluation of bladder or rectal
invasion is 71–100%, and the specificity is 88–91%
[59,
64,
68]. The absence of bladder or
rectal invasion can be diagnosed with sufficient confidence using MRI
(negative predictive value = 100%) to safely obviate invasive cystoscopic or
endoscopic staging in most patients with cervical cancer. This could
potentially lead to a reduction in staging costs and morbidity
[68]. Although pelvic node
metastases do not change the FIGO stage, paraaortic or inguinal node
metastases are classified as stage IVB.
The Role of MRI in the Evaluation of Lymph Nodes in Uterine Malignancies
In patients with endometrial and cervical cancer, the presence of lymph
node metastases suggests a poor prognosis, with a marked decrease in survival
rates [69]. For example, in
surgically treated stages IB and IIA cervical cancer, survival rates decline
from 85–90% to 50–55%, respectively, in the presence of metastatic
lymph nodes [56]. Lymph node
involvement, which is not included in the FIGO staging system for carcinoma of
the cervix, is also an important factor in the choice of adjuvant radiation
therapy in both endometrial and cervical cancer. Surgical lymph node
assessment is the gold standard for the diagnosis of lymph node metastases;
however, lymphadenectomy carries a high risk of complications, and careful
selection of high-risk patients is crucial for specialist surgical referral to
a gynecologic oncology team
[11]. Therefore, from a
clinical point of view, accurate preoperative assessment of lymph node
metastases is very important in patients with endometrial and cervical
cancer.
MRI and CT have comparable accuracies in detecting nodal metastases:
83–90% for CT and 86–90% for MRI
[7,
62,
63,
70,
71]. They both rely on size
criteria, which results in a low sensitivity (43–73% for MRI) due to the
inability to identify metastasis in normalsize lymph nodes
[5,
14,
64]. Recently, the use of
lymph node–specific MRI contrast agents, such as ultrasmall
superparamagnetic iron oxide (USPIO) particles, has been shown to improve the
sensitivity and retain the high specificity of detection of lymph node
metastases in patients with endometrial and cervical cancer
[5]. In their study, Rockall et
al. [5] showed an increase in
sensitivity from 29% using the standard size criterion (> 1 cm) to 93%
using USPIO criteria on a node-by-node basis and from 27% to 100% on a
patient-by-patient basis.
In cervical cancer, PET/CT has proved very valuable for lymph node staging
with a sensitivity and specificity of 100% and 99.7%, respectively, for lymph
nodes larger than 5 mm in diameter
[72]. Furthermore,
18F-FDG uptake within primary cervical cancer and lymph node
metastases on FDG PET are reported as independent predictors of disease-free
survival, which suggests that PET/CT may be the preferred imaging technique in
patients with advanced carcinoma of the cervix for making treatment decisions,
assessing nodal involvement, and determining prognosis
[73].
Recurrent Disease
The vagina is the sole site of recurrence in 30–50% of patients with
endometrial carcinoma recurrence; the remaining patients develop pelvic or
paraaortic lymph node involvement or systemic spread manifesting as hepatic,
pulmonary, or osseous metastasis or peritoneal carcinomatosis. Manifestations
of recurrent disease in cervical carcinoma can be characterized as typical and
atypical. Typical manifestations involve the vaginal vault and lymph nodes.
However, with the increasing use of pelvic irradiation in the treatment of
this disease, less typical patterns of recurrence are becoming more frequent.
These include peritoneal carcinomatosis and solid organ metastasis to the
liver, adrenal gland, lung, or bone
[74]. Pelvic recurrence may
involve other pelvic organs
[75]. Tumor extension into the
bladder or rectal wall is suggested by abnormally high signal intensity on
T2-weighted imaging.
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Fig. 8A —Tumor recurrence in 45-year-old woman who had undergone
hysterectomy for cervical carcinoma. Sagittal fast spin-echo (A) and
axial fat-suppressed (B) T2-weighted images show
intermediate-signal-intensity mass at vaginal vault (T), which is consistent
with tumor recurrence.
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Fig. 8B —Tumor recurrence in 45-year-old woman who had undergone
hysterectomy for cervical carcinoma. Sagittal fast spin-echo (A) and
axial fat-suppressed (B) T2-weighted images show
intermediate-signal-intensity mass at vaginal vault (T), which is consistent
with tumor recurrence.
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Fig. 9A —Tumor recurrence in 67-year-old woman who had undergone
radiochemotherapy for cervical carcinoma. Sagittal fast spin-echo (A)
and axial fat-suppressed (B) T2-weighted images show heterogeneous mass
involving uterine corpus (T), which is consistent with tumor recurrence. Note
presence of enlarged right external iliac lymph node (N in B).
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Fig. 9B —Tumor recurrence in 67-year-old woman who had undergone
radiochemotherapy for cervical carcinoma. Sagittal fast spin-echo (A)
and axial fat-suppressed (B) T2-weighted images show heterogeneous mass
involving uterine corpus (T), which is consistent with tumor recurrence. Note
presence of enlarged right external iliac lymph node (N in B).
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Vaginal vault recurrence after radical surgery for endometrial or cervical
cancer has similar appearances. This is indicated by loss of the
low-signal-intensity linear configuration of the vaginal vault and
visualization of an associated soft-tissue mass of high signal intensity on
T2-weighted images, similar to that of the primary tumor (Fig.
8A,
8B).
In patients who have undergone radiation therapy, the critical issue is
distinguishing recurrent disease from postirradiation changes. On MRI studies,
recurrent disease appears as a heterogeneous mass on T2-weighted imaging,
often similar to the appearance of the primary tumor
[75] (Fig.
9A,
9B). However, T2-weighted
images have low specificity for the detection of benign conditions, such as
inflammation and edema, that cause increased T2-weighted signal. Dynamic
contrast-enhanced MRI has been shown to be helpful in improving specificity
and accuracy of tumor recurrence, with maximum tumor enhancement occurring
between 45 and 90 seconds after contrast administration
[3]. However, early irradiation
changes and the presence of infection continue to pose a problem because
either may show enhancement. Serial imaging, imaging-guided biopsy, or PET may
be required to further clarify the situation.
Conclusion
MRI, although not officially incorporated in the FIGO staging system, is
already widely accepted as the most reliable imaging technique for the
diagnosis, staging, treatment planning, and follow-up of both endometrial and
cervical cancer. MRI protocols need to be optimized to obtain the best results
and avoid pitfalls.
In endometrial cancer, MRI is reliable in predicting the depth of
myometrial invasion and cervical extension, which correlate with the risk of
lymph node metastases. Therefore, MRI is also valuable in selecting patients
for lymph node sampling or lymphadenectomy who require specialist gynecology
referral. MRI plays a central role in the evaluation of cervical cancer,
primarily in identifying tumors without parametrial extension, thereby
stratifying patients for surgery and radiation therapy. MRI also aids in the
selection of patients for fertility-preserving surgery in early-stage disease
and in the detection of recurrent disease after treatment. In summary, MRI
plays a key role in staging, patient selection for treatment, and detection of
disease recurrence.
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Abstract
Introduction
