The Radiology Assistant : Cervical Cancer (2024)

Cervical cancer represents the fifth most common cancer typein women and - together with endometrium cancer - accounts for 0,7% of allcancer related deaths in the world (1,2).
Persistent human papilloma virus infection is the key riskfactor responsible for nearly all cervical cancers.
HIV infection is a secondknown risk factor, which increases the risk for cervical cancer byapproximately six-fold.
Most common types of cervical cancer are squamous cellcarcinoma followed by adenocarcinoma and some rare other types such asneuroendocrine tumors.

Cervical cancer can be effectively prevented by vaccinationagainst HPV.
Secondary prevention includes HPV DNA testing to screen foractive infection and prompt treatment of cervical pre-cancer.
The primarytreatment for advanced cervical cancer (stage ≥ IB) is chemoradiotherapy (CRT)followed by brachytherapy.
In the vast majority of cases, this results in a completelocal tumor response and no further surgical intervention is needed.
In theminority of cases with persistent tumor after completion of CRT, addition surgicalresection is required. Early cases are treated with conservative surgery.

The key risk factors in cervical cancer to assess on imaging aretumor size, invasion into parametrium, pelvic side wall, vagin*, bladder orrectum, and lymph node involvement.

The zonal MRI anatomy of the uterus and cervix varies with age.
During the reproductive age the different layers of the uterus and cervix are well recognizable and the muscular part of the uterine wall can be highly vascularized like in this 30-year-old woman (left image).
There is an IUD in the uterine cavity, which can be recognized as a hypointense linear structure.

In postmenopausal women the zonal anatomy becomes lessvisible and the cervical stroma, junctional zone and myometrium appear morehom*ogeneously hypointense on T2W-images, like in this 70-year-old woman (rightimage).
With age, the female reproductive organs gradually becomesmaller with a more pronounced loss in volume for the uterus compared to thecervix.

MR reporting checklist

The MRI report in cervical cancer should address the key riskfactors used to stage the patient as listed in the table in order to determinethe most appropriate treatment strategy.

Additional factors to report, that are mainly used forsurgical treatment planning:

• Distancebetween tumor and internal cervical os
• to assess feasibility of fertility sparing
• Total uterinesize … x… cm, measured in sagittal plane
• to assess feasibility of laparoscopic versus open surgery
• Associatedbenign conditions like endometriosis and leiomyoma
• Anatomicvariants

• Only small (<4 cm) early-stage tumors are amendable to upfront surgery (without chemo- or radiotherapy).
• For the remaining stages, concurrent (=combined) chemoradiotherapy (CRT) is the standard treatment.
  The CRT scheme typically consists of external beam radiotherapy combined with chemotherapy, followed by brachytherapy.
• If the tumor has spread to distant organs, lymph nodes (above the renal veins) or the peritoneum we are dealing with stage IV metastasized disease, in which case patients are typically no longer amendable to local treatment but receive palliative chemotherapy.

Tumor type and size

The tumor size should be measured in the longest possibledimension, which is often best visualized in the sagittal and sometimes in thecoronal plane.

Cervical tumors can show either an exophytic (typically inyounger women), diffuse infiltrative or endocervical (typically in older womenand/or adenocarcinomas) growth pattern.
Note that in the right image wherethere is an endocervical mass, this mass causes obstruction of the cervicalcanal with widening of the uterine cavity which is filled with high signalfluid and intermediate signal blood resulting in a blood-fluid line.

vagin*l invasion

Invasion of the vagin*l wall can be recognized on T2-weightedMRI as the extension of relatively hyperintense soft tissue extending into thevagin*l wall.

In case of vagin*l invasion you need to establish whetherthis concerns the upper 2/3 (stage IIA) or lower 1/3 (stage III) of the vagin*, as this impact patient management.
Stage IIA1/IIA2 may be eligible for upfront surgery.
In contrast lower vagin*l involvement preclude surgery and patients are referred for chemoradiation.

Parametrial invasion

When the hypointense stromal ring of the cervix is intact(left image), MRI can predict the absence of parametrial invasion with a highnegative predictive value of more than 90%.

Interruption of the hypointense stromal ring of the cervix (rightimage) and tumoral signal intensity or soft tissue mass extending into theparametrium are signs indicative of parametrial invasion (FIGO stage IIB).

Pitfall- Expansion versus invasion

This example shows a large tumor that expands the cervix.
Note that there is no actual invasion of the parametia as thehypointense stromal ring of the cervix is completely intact as indicated by thearrowheads.

Pelvic sidewall invasion

Pelvic sidewallinvasion is defined as invasion or tumor abutment within < 3 mm of theinternal obturator, levator ani or piriformis muscles, or the iliac vessels,either with or without obstruction of the ureter resulting in hydronephrosis (stage IIIB).

Sacrouterine ligament invasion

This sagittal MRI shows a locally advanced cervical cancer (circle) with extensive invasion alongthe sacrouterine ligaments (arrows).

Bladder and rectal invasion

The case on theleft shows a cervical tumor with clear invasion of the dorsal bladder wallextending into the bladder lumen.
This represents stage IV disease.

Lymph node staging

The regional lymph nodes in staging cervical cancer include all lymph nodes in the pelvis and para-aortic nodes up to the level of the renal veins.
It is important to detect para-aortic lymph node metastases, as presence of these nodes requires adaptation of the radiotherapy field.

Inguinal lymph nodes and para-aortic nodes above the level of the renal veins are considered distant metastases.

MRI has alimited diagnostic performance for pelvic lymph node staging.
It mainlyrelies on nodal size as a criterion; size cut-offs vary in literature but acommonly used threshold is 1 cm.
Reported sensitivities (±40-90%) andspecificities (±80-100%) for MRI vary widely.
PET/CT is more accurate than MRIand is used for pelvic lymph node staging, as well as for the assessment ofpara-aortic lymph nodes and distant lymph node metastases above the levelof the renal veins (3).

Images
There is a locallyadvanced cervical cancer with right-sided parametrial and pelvic sidewallinvolvement.
There is a 7 mm node dorsal to the right external iliacvein (white arrow) which is indeterminate on MRI.
Based on its size it is notclearly pathologic.
On correspondingPET/CT the primary tumor is clearly FDG-avid, as is the small para-iliac lymphnode (black arrow), thereby diagnosing it as N+.

The recommended MRI protocol is summarized in the table.

Addionalrecommendations are as follows:

• Field strength shouldbe 1.5T or higher, using a pelvic phased-array coil.
• Patient insupine position
• Use of saturationbands on the subcutaneous fat (anterior and posterior) is recommended.

Patientpreparation:

• Fasting (4-6 hours), empty bladder
• Use ofanti-peristaltic agents (Buscopan or Glucagon)
• Optional:vagin*l gel to assess upper vagin*l involvement

Note that contrast-enhanced images are not required forcervical cancer staging.
Scheduling the examination according to the menstrualcycle is not required.

Sequence planning

The MR sequences are planned relative tothe long axis of the cervical canal.
The axial plane is perpendicular to the long axis of the cervical canal.

The coronal plane is parallel to the long axis of the cervical canal.

Pitfall: variations in cervical anatomy

Theposition of the cervical canal needs to be taken into account and the perpendicular and parallel MRIsequences need to be planned accordingly.

Images
The pre-treatment MRI on the left shows an intermediate signalexophytic cervical mass.
The post-treatment MRI on the right shows that the tumor iscompletely replaced by hypointense fibrosis.
No intermediate tumor signalremains.
DWI can help in confirming the absence of tumor.
In case of a competeresponse, no further surgery is required.

Note that in this case imaging was performed after theintroduction of endovagin*l gel.
This is not routinely recommended but can be considered tohelp in the assessment of potential upper vagin*l invasion.

In a minority of casesthe standard treatment of CRT with brachytherapy is notsufficient and residual disease is suspected, as shown in this example.

Images
The pre-treatment MRI on the left shows an intermediate signal exophyticcervical mass (black arrow).
The post-treatment MRI on the right shows a smallbut clearly visible residualintermediate T2 signal mass, indicating that the tumor has not been replacedcompletely by fibrosis (white arrow).
The patient was referred to surgery,which is the standard treatment for patients with incomplete response after CRT+ brachytherapy.
DWI can aid in the detection of residual tumor after CRT.

Note that the recommended timing to evaluate response after CRT is 4 to 6 weeks after completion of treatment.
If the post-treatment MRI findings are inconclusive and there is doubt whether the patient has undergone a complete response or may still have a minor tumor remnant, patients are often further followed and response evaluation including MRI will be repeated (for example after an additional x months follow-up)

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