What is the prevalence of Ondi cells in our hospital's population's computed tomography (CT) scans and the prevalence of reporting and underreporting of these cells in our center?

Prevalence of Onodi Cells and Reporting Patterns in CT Scans

Prevalence of Onodi Cells in CT Scan Populations

Based on the available evidence, you should expect to find Onodi cells in approximately 20-53% of your hospital's CT scans of the paranasal sinuses, with most studies reporting prevalence between 33-43%. 1, 2, 3

Key Prevalence Data from Multiple Studies:

• A 2020 cone-beam CT study found Onodi cells in 42.8% (86/201) of patients, with nearly equal distribution between males (42.3%) and females (43.3%) 1

• A Malaysian hospital study reported 19.6% prevalence in 102 CT scans, noting this corresponds to the range of 7-24% reported in other CT-scan studies 2

• A Korean tertiary care center found 33.3% prevalence (54/162 patients) when identified during endoscopic endonasal transsphenoidal approach, with bilateral presentation in 23 patients and unilateral in 31 3

• A Turkish study of 618 patients demonstrated 52.7% prevalence (326/618 patients), representing one of the highest reported rates 4

• An Indian HRCT study reported 33.3% prevalence in patients with sinonasal disease and polyposis 5

Anatomical Distribution Patterns:

The position of Onodi cells relative to the sphenoid sinus varies 1:

• Superior position: 50% of cases
• Superolateral position: 41.9% of cases
• Lateral position: 8.1% of cases

Prevalence of Underreporting in Radiology Reports

The evidence strongly suggests significant underreporting of Onodi cells exists, with preoperative CT scans missing these cells in approximately 1-2% of cases when compared to intraoperative findings.

Evidence of Reporting Discrepancies:

• In the Korean study, 53 patients had Onodi cells identified on preoperative CT, but 54 were actually found during surgery, indicating 98.1% sensitivity of preoperative CT when carefully reviewed 3

• An Indian study found that intraoperative findings corresponded to only 8 out of 9 HRCT findings (p-value = 0.001), suggesting occasional discrepancies between radiological and surgical identification 5

Factors Contributing to Underreporting:

The primary reason for underreporting is that Onodi cells require specific attention during CT interpretation and are not routinely mentioned unless specifically looked for. 2, 3

• Radiologists may not routinely comment on Onodi cells unless the scan is being reviewed specifically for endoscopic sinus surgery planning 2

• The presence of Onodi cells should be routinely looked for by ESS surgeons to prevent damaging the optic nerve and internal carotid artery, suggesting current reporting may be inadequate 2

• Multiplanar reconstruction of CT scanning is essential for accurate identification, and standard axial views alone may miss these anatomical variants 4

Clinical Implications for Your Center

Recommended Approach to Assess Your Hospital's Data:

To determine the true prevalence and reporting rate at your center, you should:

1. Review a consecutive series of paranasal sinus CT scans (minimum 100-200 cases) and specifically look for Onodi cells using multiplanar reconstruction 4

2. Compare the prevalence of Onodi cells mentioned in radiology reports versus what is actually present on re-review of the images 3

3. Calculate the reporting rate as: (Number of reports mentioning Onodi cells when present / Total number of scans with Onodi cells present) × 100

4. Stratify by indication: Scans performed for surgical planning likely have higher reporting rates than incidental findings on trauma or other non-sinus-related imaging 5

Expected Findings Based on Literature:

You should anticipate finding that:

• Approximately 30-50% of your paranasal sinus CT scans will have Onodi cells present when specifically looked for 1, 3, 4

• The reporting rate in routine radiology reports may be significantly lower than the actual prevalence, particularly for scans not specifically ordered for sinus surgery planning 2, 3

• Patients with sinonasal disease and polyposis may have higher prevalence of Onodi cells compared to general population scans 5

Clinical Significance:

The presence of Onodi cells has important surgical implications 3, 4:

• Onodi cells limit exposure of the sellar floor during transsphenoidal approaches, requiring removal for complete tumor resection 3

• The co-existence of Onodi cells increases the identification of sphenoiditis 1.5-fold (p<0.05), suggesting these cells may contribute to sinus disease 4

• Onodi cells have intimate spatial relationships with the optic nerve and internal carotid artery, making their identification critical for surgical safety 1, 2, 3