Intravesical Gadoxetic acid enhanced MRI for evaluation of urinary bladder rupture in a mouse model

Retrograde intra-vesical plain film or CT cystography may not be feasible for patients with hypersensitivity towards iodinated contrast agents. This study evaluates whether retrograde gadoxetic acid-enhanced pelvic and liver MRI can detect intraperitoneal bladder rupture in a mouse model. Pelvic and liver MRI were obtained using a 7T micro-MRI scanner in 8-to-10-week-old female ICR mice (n = 28) before and after surgically induced bladder rupture. An angio-catheter was inserted into the urethra for intra-vesical injection of gadoxetic acid (0.3 mmol/kg) during MRI. Intraperitoneal contrast leakage and liver enhancement were assessed using T1 weighted images. Regions of interest were drawn on the liver and muscle (used as an internal reference) to measure signal intensity, which was then used to calculate the relative enhancement ratio and quantify the degree of liver enhancement. A paired t-test was used for statistical analysis. Intraperitoneal contrast leakage and liver enhancement were detected in all mice after bladder rupture. Some liver enhancement occurred in baseline mice but was significantly stronger under bladder rupture conditions at 30 min (P < 0.001) and 75 min (P < 0.001) post-enhancement MRI. MRI with intra-vesical gadoxetic acid injection enables detection of intraperitoneal bladder rupture by visualizing contrast leakage or selective liver enhancement. Retrograde MR cystography may serve as an iodine-free alternative to conventional retrograde cystography.