High-signal bladder urine at T (1)-weighted MR imaging performed 1–7 days after a prior gadolinium-enhanced MRI: prevalence and correlation with renal function

OBJECTIVE: To determine the prevalence of high-signal bladder urine at T (1) weighted MRI performed 1–7 days after injection of gadolinium-based contrast material and to assess for correlation with altered renal function. METHODS: The study group consisted of 267 patients who underwent MRI that included the bladder 1–7 days after a prior gadolinium-enhanced MRI. A control group consisted of 200 patients who underwent pelvic MRI and had not received gadolinium-based contrast material within the prior month. One reader recorded the relative T (1) weighted signal intensity of bladder urine and calculated the estimated glomerular filtration rate (eGFR) for each patient. A positive scan was defined as one with bladder urine T (1) weighted signal higher than that of muscle. RESULTS: 25 (9%) of 267 study group scans were positive; this included 68% ( n = 19) of scans obtained 12–24 h after gadolinium-based contrast material administration, 21% ( n = 3) after 25–36 h, 7% ( n = 2) after 37–48 h, and 3% ( n = 1) after 49–72 h. No positive scan occurred after 72 h or in the control group. Mean eGFR in positive scans obtained more than 36 h after gadolinium-based contrast material administration was significantly lower than in negative scans in the same timeframe (37 vs 76 ml/min, respectively; p = 0.01). CONCLUSION: High T (1) weighted signal in bladder urine occasionally is present on MRI performed up to 3 days after gadolinium-based contrast material administration, presumably reflecting residual excreted gadolinium-based contrast material. When visible more than 36 hours after gadolinium-based contrast material administration, such increased signal is associated with low eGFR. ADVANCES IN KNOWLEDGE: Increased signal is occasionally present in bladder urine at MRI performed up to 3 days after gadolinium-based contrast material administration. When higher signal is visible more than 36 hours after contrast administration, it is associated with decreased eGFR.