New large bowel segmentation on plain abdominal radiography in comparison with the conventional method

Area of Science:

• Radiology
• Gastroenterology
• Anatomy

Background:

• Plain abdominal radiography is a fundamental diagnostic examination in primary care.
• Understanding colon distribution on these images is crucial for accurate interpretation.

Purpose of the Study:

• To clarify the distribution of the colon on plain abdominal radiographs.
• To evaluate colon segmentation methods and identify potential inaccuracies, particularly in cases of colonic ptosis.

Main Methods:

• Forty-three healthy volunteers underwent gastric fluoroscopy followed by supine plain abdominal radiography.
• A region of interest (ROI) was defined and divided into 600 zones to analyze barium distribution in the colon.
• Colon segments (ascending, transverse, descending, sigmoid + rectum) were analyzed for ROI occupancy and compared with theoretical distributions.

Main Results:

• The large bowel occupied 76.7% of the ROI, with 55% duplication primarily in the transverse colon region.
• A standard method showed high accuracy (99.6% right, 92.2% left/sigmoid/rectal colon) but decreased sigmoid/rectal occupancy (57.2%) with transverse colon ptosis.
• A new segmentation method was developed for patients with ptosis.

Conclusions:

• Colon distribution on plain abdominal radiographs can be variable, with significant overlap in the transverse colon.
• Existing segmentation methods may underestimate sigmoid/rectal colon volume in cases of ptosis.
• A refined segmentation approach is necessary for accurate colon assessment in patients with colonic ptosis.