Positive contrast CT peritoneography, ever done it on a clinical patient?

Ability of positive and negative contrast computed tomographic peritoneography to delineate canine liver lobe fissures

Luis R Rivas 1, Gabriela S Seiler 1, Ian D Robertson 1, Hongyu Ryu 2, Kyle G Mathews 3

Background
Accurate delineation of liver lobe fissures is critical for preoperative planning in dogs with hepatic masses, as the location of a mass affects surgical feasibility and risk of complications. Ultrasound lacks the sensitivity for accurately localizing hepatic masses to specific lobes, particularly in the central division, where resection carries a higher risk of hemorrhage. This study evaluated the efficacy of positive and negative contrast computed tomographic (CT) peritoneography in improving the visualization of interlobar hepatic fissures in canine cadavers.

Methods
Study Design: Prospective cross-sectional study using 10 canine cadavers.

CT Protocol:
-Each cadaver underwent three CT scans: precontrast, after peritoneal insufflation with CO₂ (negative contrast), and after intraperitoneal administration of iohexol (positive contrast).
-Scans were reconstructed in transverse, dorsal, and sagittal planes.

Measurements: Observers independently measured the length of four fissures between hepatic lobes:
-Left lateral/left medial
-Left medial/quadrate
-Quadrate/right medial
-Right medial/right lateral
-Fissure lengths and the number of visible fissures were compared between imaging methods.

Statistical Analysis: A mixed linear model assessed differences between imaging techniques, with significance set at P < 0.05.

Results
Fissure Visibility:
-Positive contrast CT allowed measurement of 80–90% of fissures, compared to 47–80% with negative contrast and 10–27% without contrast.

Fissure Lengths:
-Positive contrast CT provided significantly longer measurable fissures compared to negative contrast or precontrast imaging (P < 0.0001).
-The left medial/quadrate fissure (important for surgical decision-making) had a mean measurable length of 2.9 cm (positive contrast), 1.1 cm (negative contrast), and 0.79 cm (precontrast) in the transverse plane.

Interobserver Agreement:
-Observers consistently measured longer fissures with positive contrast, regardless of imaging plane or lobe (P < 0.03).

Clinical Relevance:
-Positive contrast CT improved delineation of the left medial/quadrate fissure, aiding in differentiating between resectable left lobar masses and more challenging central lobar masses.

Limitations
This cadaveric study did not include hepatic masses, which may alter interlobar relationships and contrast distribution. Postmortem changes could have affected abdominal compliance and fissure visibility. Clinical application requires validation in live animals with hepatic masses.

Conclusions
Positive contrast CT peritoneography is superior to negative contrast or precontrast CT for delineating interlobar hepatic fissures in dogs. This technique may improve surgical planning and risk assessment for hepatic mass resection. Further clinical studies in live dogs are warranted to validate its utility in preoperative evaluations.

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