STAGE I ^{[4, 6, 12, 15]}

- Tumor confined to the cervix.

- IA – microinvasive disease not visible at MRI, with measured deepest invasion ≤ 5 mm (Figure 1)

Fig 1: MRI images showing a case of cervical cancer stage IA1, and a case of stage IA2, without any MRI findings (no visible tumor), both with pathological confirmation and staging. A – T2WI sagittal plane; B – T2WI coronal plane; C – T2WI sagittal plane; D – T2WI axial oblique plane; E – T1WI VIBE FS sagittal plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

          - IA1: tumor measures ≤ 3 mm in depth

          - IA2: tumor depth > 3 mm and ≤ 5 mm

- Involvement of vascular/lymphatic spaces does not change the staging.

- Stage IA is eligible for conization.

- IB: measurable disease was usually seen at MRI, with the deepest invasion ≥ 5 mm limited to the cervix.

          - IB1: maximum diameter ≤ 2 cm (Figures 2 and 3)

Fig 2: MRI images showing a case of cervical cancer stage IB1, endophytic (red arrows), with a maximum diameter ≤ 2 cm. Is possible to see a leiomyoma (blue arrows). A – T2WI sagittal plane; B – T2WI axial plane; C – DWI b-1000 axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 3: MRI images showing two cases (A and B, C, D and F) of cervical cancer stage IB1 (red arrows), with a maximum diameter ≤ 2 cm. A – T2WI sagittal plane; B – T2WI axial plane; C – T2WI sagittal plane; D – T2WI axial plane; E – ADC axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

          - IB2: maximum diameter > 2 cm ≤ 4 cm (Figures 4 and 5)

Fig 4: MRI images showing a case of cervical cancer stage IB2, partially exophytic (red arrows), with a maximum diameter > 2 cm ≤ 4 cm. A – T2WI sagittal plane; B – T2WI axial plane; C – DWI b-1000 axial plane; D – T1WI with contrast VIBE FS sagittal plane; E – T1WI with contrast VIBE FS axial plane; F – ADC axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 5: MRI images showing a case of cervical cancer stage IB2, mainly exophytic (red arrows), with a maximum diameter > 2 cm ≤ 4 cm. A – T2WI sagittal plane; B – T2WI axial oblique plane; C – DWI b-1000 axial plane; D – ADC axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

          - IB3: maximum diameter > 4 cm (Figures 6 and 7)

Fig 6: MRI images showing a case of cervical cancer stage IB3, exophytic (red arrows), with a maximum diameter > 4 cm. A – T2WI sagittal plane; B – T2WI axial oblique plane; C – ADC axial plane; D – DWI – b-1000 axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 7: MRI images showing a case of cervical cancer stage IB3, partially endophytic and partially exophytic (red arrows), with a maximum diameter > 4 cm. A – T2WI sagittal plane; B – T2WI coronal plane; C – T2WI axial plane; D – DWI – b-1000 axial plane; E – ADC axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- Stage IB1 tumors are eligible for trachelectomy.

- IB2 tumors are treated with definitive radical surgery, and IB3 with the same and concurrent chemoradiotherapy.

- T2WI and DWI are the optimal approaches to delineating tumor margins and evaluating locoregional extension.

- Any patient with a positive lymph node immediately gets upstaged to stage IIIC.

- The presence of lymphovascular invasion or involvement of the uterine body does not change the stage.

STAGE II ^{[4, 6, 12, 15]}

- The tumor invades beyond the uterus, but not to the lower third of the vagina or the pelvic wall.

- Any patient with lymph node involvement immediately gets upstaged to stage IIIC.

- IIA – disease involves the upper two-thirds of the vagina without parametrial invasion.

          - IIA1: invasive carcinoma ≤ 4 cm in greatest dimension (Figure 8)

Fig 8: MRI images showing a case of cervical cancer stage IIA1, endophytic (green arrows), ≤ 4 cm in greatest dimension with invasion of the upper two-thirds of the vagina (red arrows). Is possible to see a leiomyoma (blue arrows). A – T2WI sagittal plane; B – T2WI axial plane; C – T2WI axial oblique plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

          - IIA2: invasive carcinoma > 4 cm in greatest dimension (Figures 9 and 10)

Fig 9: MRI images showing a case of cervical cancer stage IIA2, mainly endophytic, infiltrative, and partially exophytic (orange arrows), > 4 cm in greatest dimension, with invasion of the upper two-thirds of the vagina (yellow arrows). A – T2WI sagittal plane; B – ADC axial plane; C – T2WI axial plane; D – DWI b-1000 axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 10: MRI images showing a case of cervical cancer stage IIA2, mainly exophytic, and partially endophytic (orange arrows), > 4 cm in greatest dimension, with invasion of the upper two-thirds of the vagina (yellow arrows). A – T2WI axial plane; B – T2WI sagittal plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- Evaluation of vagina involvement can be challenging and is often overestimated at MRI, particularly in the vaginal fornices. Colposcopy could be useful.

- IIB - with parametrial invasion (Figures 11 and 12)

Fig 11: MRI images showing two cases of cervical cancer (blue star) stage IIB, with parametrial invasion (red arrows). First case (A and B) with bilateral invasion. Second case (C and D) with right invasion only. A – T2WI sagittal plane; B – T2WI axial oblique plane; C – T2WI sagittal plane; D – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 12: MRI images showing several cases of cervical cancer (blue star) stage IIB, with parametrial invasion (red arrows). A – T2WI sagittal plane; B – T2WI axial plane; C – T2WI axial plane; D – T2WI axial plane; E – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- Short-axis T2WI perpendicular to the cervix is superior to axial T2WI for evaluation of parametrium.

- Parametrium invasion requires full-thickness cervical stromal invasion, and one of the following findings on T2WI: spiculated tumor to parametrial interface, tumor nodule in the parametrium, tumor encasement of parametrial vessels.

- Preserved outer rim of low signal intensity of the cervical stroma on T2WI rules out parametrial invasion.

- Microscopic disease extension cannot be excluded from an MRI.

- Ovarian involvement does not change the stage.

STAGE III ^{[4, 6, 12, 15]}

- The tumor spreads into adjacent structures (lower third of the vagina, pelvic wall, causes hydronephrosis or non-functioning kidney, and involves pelvic or para-aortic lymph nodes).

- Based on MRI evaluation, invasion of the lower third of the vagina is vaginal tissue below the level of the bladder base.

- IIIA – tumor involves the lower third of the vagina without extension to the pelvic wall (Figure 13)

Fig 13: MRI images showing a case of cervical cancer (blue star) stage IIIA, with extension to the lower third of the vagina (red arrows). A – T2WI sagittal plane; B – T2WI axial oblique plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- IIIB – extension to the pelvic wall and/or hydronephrosis or non-functioning kidney by any method, regardless of other findings (Figures 14 and 15)

Fig 14: MRI images showing a case of cervical cancer (blue star) stage IIIB, with extension to the pelvic wall (red arrows), with encasement and dilation of the ureter (green arrow), that remains dilated in the abdomen (orange arrow) conditioning hydronephrosis (blue arrow). A – T2WI sagittal plane; B – T2WI axial oblique plane; C – T2WI axial oblique plane; D – T2WI axial plane; E – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 15: MRI images showing a case of cervical cancer (blue star) stage IIIB, with dilation of the ureter (green arrow) and hydronephrosis (orange arrow). A – T2WI sagittal plane; B – T2WI axial plane; C – DWI b-1000 axial plane; D – ADC axial plane; E – T2WI axial plane; F – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- Pelvic sidewall invasion can be diagnosed at imaging when the tumor is less than 3 mm from the pelvic wall.

- IIIC – invasion of pelvic and/or para-aortic lymph nodes, irrespective of tumor size and extent. Lymph node metastases increase the risk of recurrence.

           - IIIC1: pelvic lymph node metastasis only (Figures 16 and 17)

Fig 16: MRI images showing a case of cervical cancer stage IIIC1, mainly endophytic (blue star), with pelvic bilateral lymph node metastasis (red arrows). A – T2WI sagittal plane; B – T2WI axial plane; C – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 17: MRI images showing a case of cervical cancer stage IIIC1, mainly exophytic (blue star), with pelvic bilateral lymph node metastasis (red arrows). A – T2WI sagittal plane; B – T2WI axial plane C – DWI b-1000 axial plane; D – T2WI axial plane; E – T2WI axial plane; F – ADC axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

           - IIIC2: para-aortic lymph node metastasis (Figures 18 and 19)

Fig 18: MRI images showing a case of cervical cancer stage IIIC2, with para-aortic lymph node metastasis (orange arrows), and is possible to see bilateral hydronephrosis (green stars). A – T2WI axial plane; B – T2WI axial plane; C - T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

Fig 19: MRI images showing a case of cervical cancer stage IIIC2 (blue star), with para-aortic lymph node metastasis (orange arrows), and is possible to see left hydronephrosis (green star). A – T2WI sagittal plane; B – T2WI axial plane; C - T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- FIGO hasn’t defined the imaging modality for nodal evaluation or criteria to distinguish between malignancy and inflammation/infection on imaging.

- Pelvic and para-aortic lymph nodes measuring more than 8 mm in short axis, particularly those with rounded configuration, spiculated or lobulated contour, and similar signal intensity to that of the primary cervical tumor, are suspicious at MRI and CT.

- ADC values of lymph node metastasis are significantly lower compared to benign lymph nodes, however variable cut-offs and significant overlap in ADC values limit routine clinical use.

- FDG-PET/CT is currently the most sensitive imaging approach to detect lymph node metastasis.

STAGE IV ^{[4, 6, 12, 15]}

- The tumor has extended beyond the true pelvis or has involved the mucosa of the bladder or rectum (biopsy proven).

- Distant metastases to inguinal and supraclavicular lymph nodes, lungs, bone, and others.

- IVA: spread to adjacent organs (Figures 20 and 21)

Fig 20: MRI images showing a case of cervical cancer stage IVA (blue star), with bladder endoluminal extension (red arrows), pelvic wall invasion (blue arrows), and pelvic lymph node metastasis (green arrows). A – T2WI sagittal plane; B – T2WI axial plane; C – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal..

Fig 21: MRI images showing two cases (A and B; C and D) of cervical cancer stage IVA (blue star), with extensive bladder invasion (red arrows). A – T2WI sagital plane; B – T2WI axial plane; C – T2WI sagital plane; D – T2WI axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- IVB: spread to distant organs (Figure 22)

Fig 22: MRI and CT images showing two cases of cervical cancer stage IVB (blue star), one with inguinal lymph node metastasis (red arrows) (A, B, and C), and the other (D, E, and F) with inguinal lymph node metastasis (orange arrows), and lung metastasis (green arrow). A – T2WI axial plane; B – DWI – b-1000 axial plane; C – ADC axial plane; D – T2WI sagittal plane; E – T2WI axial plane; F – CT lung window axial plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- If there is loss of the normal separating fat plane between the cervix and the bladder or rectum, or the tumor breaches the normal low T2WI signal intensity of the bladder or bowel serosa but does not invade into the lumen, this is not stage IVA.

- Bullous edema secondary to bladder wall inflammation, characterized by a thickened lobulated T2WI hyperintense, and layered appearance of the posterior bladder wall, is not tumor tissue. Bullous edema may coexist with bladder invasion (Figure 23)

Fig 23: MRI images showing a case of cervical cancer stage IVA (blue star), with bullous edema (orange arrows). A – T2WI sagittal plane; B – T2WI axial oblique plane. © Department of Radiology, Instituto Português de Oncologia de Coimbra Francisco Gentil, Coimbra, Portugal.

- Evaluation of the bladder by cystoscopy, and rectum by proctosigmoidoscopy, is recommended when the patient has symptoms or if imaging suspicion is unclear.

- FDG-PET/CT is currently the most accurate imaging approach to identify distant metastasis.