18F-FDG PET-MRI in patients with uterine cervical cancer - PETRA-C

The official staging of cervical cancer is primarily based on clinical findings
of the primary tumor (FIGO-staging)1. However, it has been shown that prognosis
is also strongly correlated with tumor size2, the FDG-uptake of the tumor3 and
lymph node involvement4. Thus, when available, imaging is done to assess exact
tumor size, parametrial and adjacent organ invasion, and lymph node status5.
MRI is the first choice in imaging uterine cervical cancer due to its good
performance showing the primary tumor and invasion in parametrial and adjacent
tissue6. 18F-FDG PET-CT is less accurate in determining exact tumor size and
parametrial invasion but performs well in case of nodal and distant
metastases7. Both MRI and 18F-FDG PET-CT show an accuracy round 80% in
detecting locoregional and paraaortal lymph node metastases8.
The first choice for curative treatment in inoperable cervical cancer (stage
IIB or higher) is (chemo) radiation9. Nowadays it is possible to equip the
PET-CT with radiation treatment planning requisites, providing information on
staging and radiotherapy treatment planning in one investigation. This
relatively new approach is standard care in the AMC since 2008.
Recently, the first clinical PET-MRI facility was installed in the Netherlands
(VUMC). Given the above-mentioned complementary role of 18F-FDG PET-CT and MRI
in uterine cervical cancer, the combination of these two imaging modalities in
one PET-MRI investigation could result in a higher diagnostic power with less
radiation burden and improved patient comfort.
There are preliminary data on software fusion of separate 18F-FDG PET-CT and
MRI investigations to achieve a complete dataset for tumor and metastasis
assessment as well as for treatment planning11. However, the combined 18F-FDG
PET-MRI in one session has not been studied yet in patients with inoperable
uterine cervical cancer.
In this study, patients will undergo 18F-FDG PET-CT in radiotherapy treatment
setting, followed by 18F-FDG PET-MRI. To perform both procedures, PET-CT and
PET-MRI, the same dose of 18F-FDG will be used without additional
administration of FDG.

Feasibility of 18F-FDG PET-MRI in inoperable uterine cervical cancer.

In this study, patients will undergo 18F-FDG PET-CT in radiotherapy treatment
setting, followed by 18F-FDG PET-MRI. To perform both procedures, PET-CT and
PET-MRI, the same dose of 18F-FDG will be used without additional
administration of FDG.
After the PET-MRI patients will be asked to fill in a questionnaire.

Patients undergo a PET-MRI investigation after 18F-FDG PET-CT, with an
additional scan time of approximately 60 minutes. There is no additional
administration of 18F-FDG, hence no additional radiation burden in that sense.
Two very low dose CT scans are going to be added to the scanprotocol to assist
attenuation correction, maximal additional radiation burden will be 4,6mSv.
Since the PET-MRI is located in the VU medical center, patients will undergo
PET-CT and PET-MRI in the VUmc instead of the AMC. This could mean some
additional travel time.
After the PET-MRI patients will be asked to fill in a questionnaire.
In the future, one 18F-FDG PET-MRI investigation might be sufficient for
appropriate staging and radiotherapy treatment planning instead of the current
situation when an MRI and a PET-CT is separately performed. This means one
visit to the imaging department instead of two, a reduction in total scan
duration of approximately 30 minutes and a reduction in radiation burden up to
20 mSV compared to the current standard care at our institution. Importantly,
this setup will result in a perfect match of MRI and PET acquisitions,
preventing current uncertainties in correlating the findings in both
examinations.