Use of Gadolinium-Enhanced MRI in a Patient with ADPKD and a Cyst Infection

Introduction: Autosomal dominant polycystic kidney disease presents significant complications to patients. One such complication is infection of a cyst. Identification of the infected cyst has proven challenging with imaging techniques including ultrasound and computer tomography (CT). Localization of the infected cyst is required with cysts larger than 5 cm for source control. Case Description: A 40-year-old woman with PMH of ADPKD and CKD 3a presented with flank pain and fever. Creatinine was 2.17 mg/dl and white blood cell count 13.8 x109/l. A urinalysis revealed 2+ blood; blood and urine cultures remained negative. Computer tomography (CT) of the abdomen and pelvis without contrast revealed innumerable cysts with no signs of infection. On hospital day three, antibiotics were broadened from ceftriaxone to ertapenem. Renal bladder ultrasound revealed enlarged bilateral kidneys (R 9.0 x 7.7 x 2.7 cm and L 8.1 x 7.4 x 17.1 cm) with innumerable simple and hemorrhagic cysts. No cyst wall thickening or hyperemia was detected. She continued to have fevers with a maximum temperature of 103.1 °F. On hospital day seven, a pre and post gadolinium MRI was completed and revealed a right upper pole cyst with inflammatory changes consistent with a large (8 cm) infected cyst. Following drainage of the cyst, her pain improved and fever resolved. Discussion: The accuracy of MRI in detecting infected renal cysts in ADPKD patients with abnormal kidney function is largely unknown due to previous contraindication of gadolinium-based contrast media (GBCM) in patients with an eGFR <30 mL/min per 1.73 m^2. Recent guidelines no longer advise against use of type 2 GBCM contrast in patients with eGFR <30. This case adds to the body of research that gadolinium enhanced MRI is an effective and safe method of localizing renal cyst infections. Importantly, it may be the best method to localize infected cysts in patients at risk for radiocontrast nephropathy.Axial T2 fat saturated showing decreased T2 hyperintensity of the large inflamed cyst (large arrow) relative to the surrounding cysts (small arrow).