In an adult female with suspected ovarian pathology, can contrast‑enhanced computed tomography (CT) of the abdomen and pelvis reliably detect ovarian lesions?

Can CT Abdomen and Pelvis Detect Ovarian Pathology?

Yes, contrast-enhanced CT of the abdomen and pelvis can reliably detect ovarian pathology, though it is not the first-line imaging modality for initial evaluation of suspected adnexal masses.

Imaging Algorithm for Ovarian Pathology

Initial Evaluation

• Transvaginal ultrasound combined with transabdominal ultrasound is the essential first-line imaging study for suspected ovarian pathology 1.
• Ultrasound can triage the majority of adnexal masses into benign or malignant categories with high accuracy 1.

Role of CT in Ovarian Pathology Detection

When CT is Appropriate

CT abdomen and pelvis with IV and oral contrast becomes the primary imaging modality in specific clinical scenarios:

• Staging known or suspected ovarian cancer - CT is the modality of choice for detecting disease extent in the chest, abdomen, and pelvis 1.
• Detecting recurrent ovarian cancer - Contrast-enhanced CT has sensitivity of 58-84% and specificity of 59-100% for identifying tumor recurrence 1.
• When ultrasound is technically limited or patient factors preclude adequate sonographic evaluation 2.

CT Detection Capabilities

What CT detects well:

• Larger ovarian masses and complex adnexal lesions 2, 3.
• Ascites (excellent sensitivity) 4.
• Peritoneal implants and metastases 1.
• Lymphadenopathy throughout abdomen and pelvis 1.
• Tumor deposits in mesentery, omentum, porta hepatis, liver, diaphragm, and lung parenchyma 1.
• Adhesions to uterus and adjoining structures (CT superior to ultrasound for this) 3.

CT morphologic features predictive of malignancy:

• Heterogeneity in solid lesions 2.
• Multilocularity (>3 locules) in cystic lesions 2.
• Irregular and thickened cystic septations or walls 2.
• Internal vegetations 2.
• Irregular lesion contour 2.

Important CT Limitations

Critical pitfall: Small peritoneal or mesenteric implants <5 mm are difficult to detect on CT 1, 4.

• Small tumor deposits (<7 mm) on bowel wall or along peritoneum may be missed 1.
• Non-contrast CT has severely limited ability to identify small peritoneal/mesenteric implants or lymphadenopathy among bowel loops 1.
• Intravenous contrast is essential for optimal detection and characterization of lesions 1.

CT Performance in Specific Populations

Postmenopausal Women with Incidental Findings

• Simple cysts on CT in postmenopausal women with non-ovarian malignancy have 0% malignancy rate (95% CI: 0.0-3.0%) 5.
• Complex cysts are significantly more likely to be malignant than simple cysts (p=0.002) 5.
• Solid-cystic lesions have higher malignancy risk than complex cysts (p<0.001) 5.
• A size threshold of 3 cm (rather than 1 cm) may be appropriate for recommending follow-up of simple cysts 5.

Diagnostic Accuracy

• CT has 84% accuracy for histologic diagnosis of adnexal masses versus 56% for ultrasound in one comparative study 3.
• Contrast-enhanced helical CT demonstrates areas under ROC curves of 0.88-0.90 for diagnosing malignancy in adnexal masses 2.
• CT detected 92% of surgically confirmed adnexal masses in one series 2.

When CT Should NOT Be Used

CT is not useful for:

• Initial characterization of adnexal masses already well-characterized on ultrasound 1.
• Further evaluation of lesions suspicious for malignancy on ultrasound - MRI with IV contrast is superior for this indication 1.
• Routine follow-up of simple benign-appearing cysts 1.

MRI Superiority for Indeterminate Lesions

When ultrasound shows an indeterminate adnexal mass, contrast-enhanced MRI is the modality of choice rather than CT 1:

• MRI increases posttest probability of cancer more than CT (premenopausal: 80% vs 38%; postmenopausal: 95% vs 76%, p<0.001) 1.
• MRI has 91% overall accuracy for diagnosing malignancy 1.
• MRI better characterizes specific benign entities (endometriomas, dermoids, fibromas) 1.

Clinical Context Matters

• Primary colorectal cancer significantly increases likelihood of malignant adnexal lesions (OR 10.2, p<0.001) 5.
• Presence of non-ovarian peritoneal metastases strongly correlates with adnexal malignancy (p<0.001) 5.
• Ancillary findings on CT (ascites, peritoneal implants, lymphadenopathy, pleural effusion) are highly predictive of malignancy 2.