Feasibility study of abdominal organs imaging using a flexible interventional ultrasound catheter

Objective To evaluate the feasibility of a novel flexible ultrasound imaging catheter for high-resolution real-time imaging of deep abdominal structures via percutaneous intervention. Methods A self-developed flexible ultrasound catheter system（outer diameter：3.3 mm，integrated with a 10.5 MHz high-frequency linear array transducer and 4-degree-of-freedom active deflection）was used to image abdominal organs（liver，gallbladder，pancreas，etc.）in two healthy beagles via percutaneous puncture，with comparison to conventional surface convex array probes（3.6 MHz）. Image quality was assessed using a double-blind design，independently scored by five ultrasound physicians with over 10 years of experience on a 6-point scale. Mixed-effects ordinal logistic regression（adjusted for dog，organ，and evaluator variability）was employed for inter-group comparisons，with effect sizes quantified by Cliff's delta. Characteristic anatomical structure detection rates were analyzed using generalized linear mixed models（Firth correction for zero events）. Inter-rater reliability was assessed via intraclass correlation coefficient（ICC，two-way random model）and Kendall's coefficient of concordance. Results The flexible catheter group demonstrated significantly superior image quality compared to the surface probe group. The most pronounced improvement was observed in adrenal imaging（5 points vs. 1 point，P<0.001，δ=0.92），while pancreatic imaging showed no significant difference（2 points vs. 2 points，P=0.812，δ=0.05）. Other organs exhibited significant quality enhancements（all P<0.05，δ=0.63～0.81）. The catheter significantly improved detection rates of characteristic structures：gastric wall stratification（90% vs. 10%，OR=36.0，P<0.001），adrenal corticomedullary differentiation（80% vs. 0，OR=∞，P<0.001），and gallbladder/small intestinal wall trilaminar structure（80% vs. 20%，OR=12.0，P=0.003）. The high-quality image rate（≥5 points）reached 77.8%，representing an 11.6-fold improvement over surface ultrasound（6.7%，P<0.001）. Inter-rater reliability was excellent（ICC=0.85，W=0.79）. Conclusions Percutaneous flexible ultrasound catheter imaging significantly enhances resolution and anatomical detail visualization of deep abdominal structures. Combining minimally invasive access with operational flexibility，this technology shows promise for providing precise image guidance in minimally invasive procedures.