Fig. 10
From: Assessment and characterisation of common renal masses with CT and MRI
Imaging presentation of xanthogranulomatous pyelonephritis (XP) and bacterial pyelonephritis (PN) on CT and MRI: XP on CT (upper row): a pelvic stone is clearly visible with a diffuse thickening of the pelvic wall, which shows enhancement in the arterial (arrow in a) and venous (arrow in b) phase. The CT urogram (arrow in c) shows the hydronephrosis owing to an obstruction at the level of the uretero-pelvic junction. XP on MRI (middle row): the thickening of the pelvic wall is clearly detectable on T1-weighted (arrow in d) and T2-weighted (arrow in e) images, and an enhancement of the pelvic wall in T1 in the venous (arrow in f) phase. Contrast-enhanced MRI urogram (g) enables a similar presentation of the upper urinary tract in comparison to the CT urogram. PN on MRI (lower row): ADC mapping shows a decreased signal (arrow in h) and DWI (b-value: 800) a heterogeneous pattern of renal parenchyma (arrow in i). In the venous phase small non-enhanced subcapsular areas are detectable (arrow in j). MR urogram shows no hydronephrosis in this case of ascending PN (arrow in k)