Imaging of ovarian

malignant germ cell

tumorsMRI, CT and PET/CT

Luca Guerra – Dolci Carlotta

Nuclear Medicine – Molecular Bioimaging Centre

San Gerardo Hospital – University of Milan Bicocca

Malignant Ovarian Germ Cell

TumorsConsolidated applications of radiological

Imaging

• CT and MRI

– Differential diagnosis

– Staging (T-N-M)

– Restaging

– Evaluation of Therapy Response

– Suspected relapse

Immature teratoma- MRI

T1 - A T2 - B FS_T1 -C

Immature teratoma- CT

Radiological features for differential diagnosisRadiological features for differential diagnosis

Dysgerminoma - MRI

T1 T2Dysgerminoma - CT

Radiological features for differential diagnosisRadiological features for differential diagnosis

Endodermal sinus tumor - MRI

Endodermal sinus tumor - CT

T2

T1

Radiological features for differential diagnosisRadiological features for differential diagnosis

Radiological imaging useful for the differential

diagnosis of the OGCT and the definition of the

local extension of the disease.

N staging in ovarian germ cell

tumor

Radiological Imaging

• Morphologic criteria

– size: > 8 mm in the pelvis and >10 mm in the

abdomen

– shape: round or irregular

– internal architecture: signal intensity heterogeneity

on T2-weighted MRI images or central necrosis on

CT images

McMahon et al., Radiology 2010, 254: 31

Detection of metastases (M)

Radiological Imaging

• CT and MRI in assessment of distant

metastases

– Peritoneal mts (nodule, peritoneal fat

infiltration, free fluid)

– Hematogenous mts (liver, lung, and rarely

brain) more frequently than epithelial tumors

The Tracer (not the only one) – [18F]-FDG

Many tumors base their metabolism on glucose consumption

[18F]-FDG is taken up by the tumor but it is not metabolized

Basics of PET/CT

glucose fluorodeoxiglucose

CT PET

Basics of PET/CTThe scanner

CT PET

Basics of PET/CTThe scanner

PET/CT limitations

• Diabetes (cut-off 170 mg/dL; optimal below 140 mg/dL)

• Inflammations (False Positive)

• PET/CT Scanner resolution ~ 5 mm

• False Negative

• Low grade, borderline, mucinous type

• False Positive

• Ovarian Cysts, Ovarian mature teratoma, Mioma

PET/CT limitations

• False Positive: Mioma

PET/CT limitations

• False Negative: epithelial ovarian ca. – mucinous type

Malignant Ovarian Germ Cell

Tumors

What Role for PET ?

Role of PET & PET/CT in ovarian germ cell

tumors in scientific literature

No data regarding PET & PET/CTNo data regarding PET & PET/CT

May 2010

Is there a role for PET/CT in T

staging?

303717 Endodermal Sinus Tumor – staging PET

Limited resolution (5-6

mm) not adequate to

define neither

anatomical

characteristic of the

lesion nor the

involvement of pelvic

organs.

Possible role for

metabolic

characterization of

pelvic mass

N staging in ovarian germ cell

tumor

Role of PET/CT

• Radiological Morphologic Criteria

– size: > 8 mm in the pelvis and >10 mm in the

abdomen

– shape: round or irregular

– internal architecture: signal intensity heterogeneity

on T2-weighted MRI images or central necrosis on

CT images McMahon et al., Radiology 2010, 254: 31

Is morphology sufficient ?Is morphology sufficient ?

Is morphology a sufficient

criteria

for N definition ?424507 Endometrial ca.

staging

Anatomical and

metabolic abnormalities

on PET/CT scan in

paraortic LN

Is morphology a sufficient

criteria for N definition ?

424507 Endometrial ca.

staging

Metabolic abnormality in

anatomically normal (9

mm diam.) cervical LN

• Five year survival was 95.7% in pts with LN- compared to 82.8% in pts with

LN+ (p < 0.001).

• Lymph node involvement was an independent predictor of poor survival

with a hazards ratio of 2.87 (95% CI 1.439–5.725; p < 0.05)

Detection on nodal involvement (N)

Presence of lymph node metastasis in ovarian

malignant germ cell tumors is a predictor of

poor survival

Kumar et al. Gynecol Oncol 2008;110:125

• 613 pts from the Surveillance, Epidemiology, and End Results Program (SEER) from

1988 to 2004 with a histologic diagnosis of OGCT after surgical resection +

lymphadenectomy

• Prevalence of lymphnode metastasis 18.1% (111/613)

- dysgerminoma 28%

- malignant teratoma 8%

- mixed germ cell tumors/pure non-dysgerminoma 16%

Nodal involvement and

survival Lymphadenectomy

and survival

Detection on nodal involvement (N)

Presence of lymph node metastasis in ovarian

malignant germ cell tumors is a predictor of

poor survival

Prevalence of lymphnode metastasis in OGCT 18.1%

Lymphadenectomy performed in more than 80% of Lymphadenectomy performed in more than 80% of

patients without LN metastases.patients without LN metastases.

Possible role of 18 F-FDG PET/CT

in staging nodal stagingCould be PET/CT indicated in OGCT for excluding

patients from unnecessary lymphadenectomy?

PurposePurpose: to determine prospectively the diagnostic accuracy of 18F-FDG

PET/CT in the detection of nodal metastases in patients with high risk

endometrial cancer.

• 37 pts with high risk endometrial cancer

• 18 F-FDG PET/CT for N staging and submitted to total hysterectomy, bilateral salpingo-

oophorectomy and systematic pelvic lymphadenectomy

• PECT/CT findings compared with histologic result for nodal involvement

Signorelli M, Guerra L, Buda A et al. Gynecol Oncol 2009

PET/CT resultsPET/CT results (pts based) Sensitivity 77,8%; Specificity 100%; PPV

100%; NPV 93,1%;NPV 93,1%; Accuracy 94,4%

ConclusionConclusion: 18F-FDG PET/CT is an accurate method for the

presurgical evaluation of pelvic nodes metastases. The high negative

predictive value may be useful in selecting patients who might avoid

lymphadenectomy, minimizing operative and surgical complications.

Detection of metastases (M)

by 18F FDG PET/CT• 18F-FDG PET/CT in assessment of

distant metastases

– Peritoneal mts

• nodules > 5 mm (limitation thin layers spread;

aspecific bowel activity)

– Hematogenous mts

• Liver (limitation high bkg; movement)

• Brain not indicated

• Lung

4D PET/CT

Liver mts

420504 male 49 yr - CRC

restaging for metastases

Equivocal finding: a third metastasis?

4D PET/CT

Improving Quantification

420504 male 49 yr - CRC

restaging for metastases

Detection of metastases (M)

Lung

18F-FDG PET/CT in malignant

ovarian germ cell tumors -

experience in HSG• 46 PET/CT studies in 29 pts treated in

Gynecological Dept. from 2000 to 2009.– 18 pts 1 PET/CT study;

– 11 pts more than 1 PET/CT study

Histology N° pts %

Dysgerminoma 17 59%

Immature teratoma 6 21%

Yolk sac tumor 3 10%

Mixed tumors 3 10%

55% stage I

45% stage III-IV

stage (n° pt & %)

9; 32%

7; 24%

9; 31%

1; 3%

2; 7% 1; 3%

IA

IC

IIIC

III

IV

Clinical Indicationsn° of PET/CT studies and %

PET/CT experience in HSG

48%28%

11%

9% 4%

18F-FDG PET/CT and pathologic results

pts-based analysis

• 19 PET/CT studies (19 pts)

– 2 staging

– 9 post surgical restaging

– 5 chemotp. response

– 1 evaluation after surgery & adjuvant

chemotp.

– 2 suspected relapse

18F-FDG PET/CT and pathologic

results

pts-based analysis

• 11 PET/CT negative studies

– confirmation by surveillance LPS

• 2 < 1 month

• 7 1 - 2 months

• 2 5 - 8 months

NO false negative

8 restaging after

surgery

• 8 PET/CT positive studies (1 suspicious)

– Surgical intervention 1-2 months after PET/CT

– 4 TP results

– 4 FP results50% false positive!

1 restaging after surgery

Accuracy in 9 post surgical restaging pts =

88,8%

19 PET/CT studies

Case 1: 18F-FDG PET/CT insuspect of relapse of a mixed

germ cell tumor

Histology: nodule withHistology: nodule with

foam cells infiltrationfoam cells infiltration

Mixed germinal tumor;

suspected disease relapse

18F-FDG PET/CT findings and

correlation with clinical course

• 27 PET/CT studies (17 pts)

– 13 post surgical restaging

– 7 chemotp. response evaluation

– 4 followup

– 3 suspected relapse

18F-FDG PET/CT findings and

correlation with clinical course

• 11 PET/CT negative– 7/11 PET/CT confirmed as TN at followup (FU range 12 – 42

months)

– 3/11 PET/CT before (1) or during chemotp (2)

– 1/11 followup ongoing

• 12 PET/CT positive + 1 suspicious– 3/12 confirmed by other imaging

– 9/12 submitted to chemotp

• 4 PET/CT equivocal– All negative at the followup (FU range 12 – 36 months)

27 PET/CT studies

Conclusions

• Few data available for drawing conclusion

• Possible role of PET/CT in restaging after

surgery (high NPV to be confirmed)

• Possible role of PET/CT in nodal

presurgical staging in tumor

macroscopically limited to pelvis (high

NPV expected)