Incidental Adnexal Masses Detected at Low-Dose Unenhanced CT in Asymptomatic Women Age 50 and Older: Implications for Clinical Management and Ovarian Cancer Screening

©RSNA, 2010 • radiology.rsna.org

ByDr. Naglaa Mahmoud

Registrar of Clinical RadiologyKCCC

Introduction:

Ovarian cancer remains the leading cause of gynecologic

cancer–related deaths in the United States.

Five-year survival for ovarian cancer is greater than 90% for

localized disease, but the overall survival is well below 50%

because the majority of cases are advanced at diagnosis.

Introduction:

Unlike transvaginal ultrasonography or MR imaging, CT is

not intended for primary pelvic or gynecologic evaluation in

women. However, the widespread use of abdominal / pelvic

CT for a variety of other indications unavoidably includes

adnexal evaluation, often resulting in incidental lesion

detection.

Introduction:

In the case of CT colonography screening in asymptomatic

postmenopausal women, the identification of adnexal

lesions nearly always represents an unsuspected

incidental finding which allows for a unique opportunity to

investigate this well-suited cohort.

The purpose of this study was:

To determine the prevalence, work-up, and outcomes of

indeterminate adnexal masses identified at low-dose

unenhanced CT scan in asymptomatic women age 50 and

older undergoing colonography screening.

Materials and Methods:

This study was institutional review board approved.

Informed consent was waived.

The fate of indeterminate adnexal lesions identified at

unenhanced CT in 2869 consecutive women (mean age,

57.2 years; age range, 50–97 years) undergoing

colonography screening between April 2004 and

December 2008 was evaluated.

CT Technique

CT imaging of the abdomen and pelvis was performed for

the purpose of colorectal cancer screening by using a

colonographic technique.

The preimaging protocol for colonography includes bowel

preparation the evening before examination and gaseous

distention of the colon during the examination.

CT Technique

Supine and prone acquisitions were obtained with 8 or 16-

detector CT scanners by utilizing 1.25-mm collimation, 120

kVp, static (50–75 mAs) tube current technique, and 1-mm

reconstruction interval.

For extracolonic evaluation, the supine series was

reconstructed with a 5-mm section thickness at 3-mm

intervals.

CT Technique

Extracolonic CT interpretation was performed alongside the

prospective colorectal evaluation by one of five board-certified

abdominal radiologists, all with at least 10 years of experience

in gastrointestinal and genitourinary body CT interpretation.

Prospective categorization of extracolonic findings was applied

in all cases by utilizing the CT Colonography Reporting and

Data System (C-RADS).

CT Technique

According to C-RADS, E1 (normal finding) and E2

(unimportant finding) categories do not require further

work-up, whereas E3 (likely benign but incompletely

characterized) and E4 (potentially or definitely important)

findings often necessitate further evaluation.

Identification of the Study Cohort

The positive study cohort was defined by the presence

of an adnexal lesion with a C-RADS category of E3 or

E4.

Results:

One hundred eighteen women (mean age, 56.2 years),

representing 4.1% of the screening cohort, had an

indeterminate adnexal mass (108 unilateral, 10 bilateral; Mean

size, 4.1 cm) at prospective CT interpretation.

A total of 80 women underwent some combination of further

imaging evaluation (n = 76) (transvaginal ultrasonography [ n =

71], pelvic magnetic resonance imaging [ n = 7], contrast

material– enhanced CT [ n = 7]) and/or surgery ( n = 26).

Results:

Mean serum CA-125 level in 33 women was 12.8 U/mL;

levels were normal ( < 35 U/mL) in 32 (97%) cases (range,

3–26 U/mL) and mildly elevated (41 U/mL) in 1 case.

Results:

Final pathologic findings of surgically excised lesions were

cystadenoma or cystadenofibroma ( n = 14; 11 serous, three

mucinous); non neoplastic cysts ( n = 5; two

endometriomas); mature teratoma ( n = 3); hydrosalpinx ( n =

2); fibroma (n = 1); and benign Brenner tumor ( n = 1).

Three additional teratomas were diagnosed at index CT only.

No ovarian cancers were prospectively identified.

Various adnexal pathologic findings identified at routine CT colonography screening and surgically removed after further work-up. CT colonographic images in six women (age range, 51–63 years) show (a)mucinous cystadenoma,(b)bilateral serous cystadenomas,

(c) ovarian fibroma, (d) endometrioma,

(e) paraovarian inclusion cyst, and (f) hydrosalpinx

Results:

A systematic search for subsequent diagnosis of ovarian

cancer in the larger cohort of 2751 women without an

adnexal mass of C-RADS category E3 or E4 at CT

colonography revealed 4 cases of ovarian cancer that

manifested 15–44 months (mean, 26.8 months) after a

negative finding at CT examination.

Results:

Pathologic diagnoses included 2 cases of mucinous

cystadenocarcinoma, 1 case of papillary serous carcinoma,

and 1 case of a poorly differentiated adenocarcinoma for

which ovarian versus peritoneal origin could not be

ascertained.

Mucinous cystadenocarcinoma that manifested 3 years after negative findings at CT colonography screening examination in 67-year-old woman. (a) Index CT colonographic image demonstrates symmetric-appearing normal ovaries. (b) Diagnostic contrast-enhanced CT image obtained 3 years later shows a large complex solid and cystic mass, which originated from the left ovary.

Discussion:

Ovarian cancer has a greater annual mortality than cervical and

endometrial cancers combined.

Prognosis remains poor in most cases because the disease is

usually advanced at diagnosis.

Discussion

Although effective screening for ovarian cancer is highly

desirable, there is currently no convincing evidence that it can

reduce mortality among average-risk women. The findings of

this study further support this unfortunate situation.

Furthermore, a negative finding at CT was not protective

against subsequent development of ovarian cancer, with all

four cases occurring in this cohort.

Discussion:

The main factors that diminish the potential utility of

screening are that indolent benign adnexal lesions are

relatively common in postmenopausal women, but ovarian

cancer is relatively rare and tends to grow rapidly.

Management algorithms generally recommend further work-

up of nearly all discrete adnexal masses detected at CT in

postmenopausal women.

Discussion:

In contrast to ovarian cancer, a number of other

extracolonic cancers have been identified at CT

colonography screening, generally at an early

presymptomatic stage with a favorable outcome.

This suggests that ovarian cancer is an aggressive tumor

that has a rather narrow window for presymptomatic

screening that may preclude effective screening detection in

the general population.

Discussion:

More sophisticated risk factor assessment may be required

to effectively identify and manage high-risk cases to improve

the overall yield of ovarian cancer screening.

Established risk factors include BRCA mutations, Lynch

syndrome, family history of ovarian or breast cancer, and a

personal history of breast cancer.

Limitations of the study

All CT examinations were performed by using a colonographic

technique with low-dose imaging and without intravenous

contrast material.

With the exception of ovarian teratomas, the ability to fully

characterize adnexal masses at low-dose unenhanced CT is

limited.

Conclusion:

Incidental indeterminate adnexal lesions were relatively

common at unenhanced CT scan (4.1%), but subsequent

work-up revealed no ovarian cancers.

Furthermore, a normal finding at CT was not protective

against short-term development of ovarian cancer.

More sophisticated risk factor assessment is needed to

identify women at higher risk.

Thank you