Primary 2D versus primary 3D polyp detection at screening CT colonography.

Area of Science:

• Medical Imaging
• Gastroenterology
• Radiology

Background:

• Existing computed tomography colonography (CTC) trials show mixed results regarding 2D vs. 3D polyp detection sensitivity.
• Direct evidence comparing primary 2D and 3D polyp detection sensitivity in CTC is lacking.

Purpose of the Study:

• To assess the sensitivity of primary 2D polyp detection in CTC using cases from a Department of Defense screening trial.
• To compare the 2D detection results with primary 3D CTC evaluation and previous 2D CTC trials.

Main Methods:

• Ten experienced radiologists retrospectively interpreted 730 CTC cases using a primary 2D approach, with 3D for problem-solving.
• Performance was compared to the original trial's primary 3D CTC results from 1,233 cases.
• Reviewers in the 2D arm had >100 CTC cases interpreted, exceeding the experience of reviewers in the original 3D trial.

Main Results:

• Primary 2D CTC sensitivity for adenomas ≥6 mm was 44.1%, significantly lower than 3D CTC's 85.7% (p < 0.001).
• Sensitivity for adenomas ≥10 mm was 75.0% for 2D vs. 92.2% for 3D (p = 0.027).
• By-patient specificity was comparable: 98.1% for 2D vs. 97.4% for 3D at the 10-mm threshold (p = 0.336).

Conclusions:

• Primary 2D CTC demonstrates significantly lower sensitivity for polyp detection compared to primary 3D CTC in low-prevalence screening cohorts.
• The observed low 2D sensitivity aligns with findings from previous CTC trials utilizing a primary 2D approach.