Evaluation of the renal parenchymal retention of iodinated contrast agent during follow-up computed tomography performed one day after undergoing contrast-enhanced computed tomography

Purpose: To examine the frequency and patterns of renal parenchymal retention of iodinated contrast agent during follow-up computed tomography (CT) performed one day after undergoing contrast-enhanced CT and to evaluate the association with the renal function before and after contrast-enhanced CT. Materials and Methods: This retrospective study included 55 patients who underwent follow-up CT the day after contrast-enhanced CT had been performed. Two radiologists categorized the retention patterns on a scale of 0-6 (0: no retention, 1: diffuse parenchymal, 2: diffuse cortical, 3: subcapsular tiny nodular, 4: cortical wedge-shaped, 5: medullary focal, 6: renal pelvic). In addition, we collected the patients' clinical data, including the development of contrast-induced nephropathy (CIN). Results: A total of 37 patients (67 %) showed retention of contrast agent in the kidney (retention group), while 18 did not (non-retention group). A diffuse parenchymal pattern and renal pelvis pattern were the most common. High levels of creatinine (Cre) and blood urea nitrogen (BUN) before contrast-enhanced CT were significantly associated with the retention in the kidney (p = 0.018, 0.006, respectively). The frequency of the development of CIN was significantly higher (p = 0.021) in the retention group (10/37) than in the non-retention group (0/18). A diffuse parenchymal pattern and diffuse cortical pattern were significantly more common in patients with CIN than in those without CIN (p = 0.003, p = 0.045, respectively). Conclusion: Renal parenchymal retention of iodinated contrast agent the day after contrast-enhanced CT was a frequently recognized finding and was associated with renal dysfunction. This finding, especially diffuse parenchymal and cortical patterns, may be a potential biomarker of CIN development.