EXTRACOLONIC FINDINGS-IDENTIFICATION AT LOW-DOSE CTC.

Area of Science:

• Radiology
• Medical Imaging
• Gastroenterology

Background:

• Computed tomography colonography (CTC) offers advantages over optical colonoscopy by visualizing extracolonic pathology.
• Detecting extracolonic abnormalities with CTC typically requires higher radiation doses than identifying colorectal lesions.
• Investigating ultra-low-dose (ULD) CTC is crucial for optimizing radiation exposure while maintaining diagnostic efficacy for extracolonic findings.

Purpose of the Study:

• To evaluate the impact of ultra-low-dose (ULD) computed tomography colonography (CTC) on the detection and characterization of extracolonic findings.
• To compare the diagnostic performance of ULD CTC with standard-dose (SD) CTC for extracolonic pathology assessment.

Main Methods:

• A prospective study involving 49 patients with colorectal symptoms undergoing CTC with both ULD (0.9 mSv) and SD (3.6 mSv) series.
• Five radiologists independently and blindly assessed ULD and SD series using a ViewDEX protocol with confidence and follow-up assessments (C-RADS E0-E4).
• Reference findings were established by combining CTC data (ULD, SD, contrast-enhanced) and a 4-year radiological/clinical follow-up.

Main Results:

• A statistically significant difference favored SD CTC for the overall detection of reference findings (E2-E4).
• No significant difference was observed between ULD and SD CTC in classifying possibly important/important reference findings (E3-E4).
• Significant inter-observer variability was noted in the interpretation of extracolonic findings.

Conclusions:

• Ultra-low-dose CTC (0.9 mSv) demonstrates comparable efficacy to standard-dose CTC (3.6 mSv) for identifying clinically relevant extracolonic pathology.
• The diagnostic performance for clinically significant extracolonic findings is similar between ULD and SD CTC.
• High inter-observer variability necessitates further investigation and standardization in interpreting extracolonic findings on CTC.