PMC6159245_01
(a-d) Ultrasound image showing hydronephrosis (a) Non-contrast CT shows hydronephrosis (b) with sudden tapering of the renal pelvis (white arrow) at the pelviureteric junction. (c,d) Axial T2 weighted image showing perinephric fat stranding with debris (bent arrow) within the calyces.
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(a-g) (Same patient as in Figure 1) (a) Coronal maximal intensity projection of a heavily T2 weighted image showing a filling defect in the interpolar and lower polar calyx (short white arrow) with sudden tapering at the pelviureteric junction (curved arrow) on the right side. Mild hydronephrosis with narrowing at the pelviureteric junction is also noted on the left side. (b) Shows a magnified image with a filling defect in the lower polar calyx on the right side. (c) Shows a cleft (small white arrow) at the lower pole calyx. (d,e) Show filling defect in the interpolar calyx (curved white arrow) with debris (long white arrow) within the calyx. (f,g) Show diffusion restriction (small white arrow) at the tip of the medullary pyramids on the right side with their corresponding apparent diffusion coefficient maps [b = 0,800 s mm-2, TR (Relaxation time)5000 ms, TE(Echo time) 95 ms, ET(Echo train) = 1]. Apparent diffusion coefficient value measured at the lower pole calyx of the right kidney was 1.004x 10-3 mm2 s-1.
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These imaging findings were suggestive of a right pelviureteric junction stricture with papillary necrosis (Figure 2).
PMC6159245_02
(a) Coronal maximum intensity projection of a 3D MR cholangiopancreatography sequence showing filling defects within the calyceal system (short straight white arrow) with sudden tapering of the right ureter at mid-ureteric level (Long straight white arrow). (b) Coronal 2 D fast spin echo image showing perinephric fat stranding around the right kidney with a filling defect (curved arrow) at the right interpolar calyx. (c) Shows a single section of a 3D MR cholangiopancreatography image showing T2 hyperintense urine around the interpolar calyx on the right side suggestive of a rim/ring sign (straight arrow). (d) Shows a diffusion-weighted image showing diffusion restriction (straight arrow) at the calyx and tip of the renal pyramid. The corresponding apparent diffusion coefficient image is provided in (e). [b = 0, 800 s mm-2, TR 4500 ms, TE 90 ms ET = 1]. Apparent diffusion coefficient value derived was 0.989x10-3 mm2 s-1.
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A ring sign was seen in the calyces on the right side (Figure 3).
(a-c) (Same patient as in Figure 3) Coronal reformats of CT images showing papillary calcification in both kidneys (arrows).
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This CT showed papillary calcifications on both sides (Figure 4).
PMC6159245_03
Ultrasound image showing hydronephrosis with a dilated pelvicalyceal system. Hyperechoic material is noted within the interpolar calyx (long white arrow).
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Initial evaluation by ultrasound imaging showed left-sided hydronephrosis (Figure 5).
(a-c) (Same patient as in Figure 5) (a) -Showing sudden tapering (straight arrow) with filling defect (curved arrow at insert) in the upper ureter causing hydroureteronephrosis. (b) Showing filling defect(straight arrow) in the upper pole calyx. (c) Shows diffusion restriction in the upper polar calyx and the tip of the pyramid (straight arrow). (d) shows the apparent diffusion coefficient map which shows hypointensity corresponding to the region of diffusion restriction. [b = 0, 800 s mm-2, TR 4500 ms, TE 90 ms ET = 1]. Apparent diffusion coefficient value derived was 1.090x10-3 mm2 s-1.
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Further, coronal slice of the 3D MR cholangiopancreatography image showed filling defect in the upper polar calyx and diffusion-weighted images showed diffusion restriction in the calyx and renal pyramid (Figure 6).
PMC6159245_04
(a) Shows a coronal maximum intensity projection of a 3D MR cholangiopancreatography sequence showing a filling defect in the upper ureter (short straight arrow) and non-visualized right lower pole calyx suggesting a phantom calyx sign. Also noted in this image is the termination of the right ureter in the ileum (long straight arrow) and a medially deviated left ureter (curved arrow). (b) Shows a filling defect in the lower pole calyx (short straight arrow) of left kidney with a ring sign (long straight arrow) in the right interpolar calyx. (c) Shows a coronal T2 weighted image of a bulky right kidney, with a filling defect in the renal pelvis, calyces and proximal ureter (straight arrows). (d) Shows a diffusion-weighted image with corresponding apparent diffusion coefficient map showing a focus of parenchymal diffusion restriction (short straight arrow) with diffusion restriction in the renal pelvis (curved arrow) suggesting pyelonephritis with pyonephrosis. The corresponding ADC hypointensity is noted. Thus a diagnosis of pyelonephritis with papillary necrosis and pyonephrosis was made.
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Further, a bulky right kidney with areas of parenchymal diffusion restriction surrounded by free fluid with filling defects in the right ureter, calyces and the renal pelvis suggested a diagnosis of right-sided pyelonephritis with bilateral papillary necrosis (Figure 7).
(a-d) (Same patient as in Figure 7) (a,b) Show diffusion restriction within the calyces of the right kidney with no evidence of calyceal diffusion restriction in the left kidney. However, subtle parenchymal diffusion restriction is noted in the left kidney. Apparent diffusion coefficient (ADC) images are provided in (d) showing the corresponding ADC hypointensity [b = 0,800 s mm-2, TR 4500 ms, TE 90 ms ET = 1]. ADC value at the calyces of the right kidney was 0.859x10-3 mm2 s-1. (c) Shows a percutaneous nephrostogram performed through a percutaneous nephrostomy tube with narrowing of the mid-ureteric segment with free flow of gastrograffin into the ileum (arrow). Irregular calyces are noted in the right kidney.
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Further evidence of diffusion restriction was seen at the calyces and the tips of the renal pyramids (Figure 8). After the procedure, a nephrostogram showed free flow of contrast through the right pelvicalyceal system into the ileum (Figure 8).
PMC6159245_05
(a-c) (a) shows a 3D MR cholangiopancreatography image of the patient with bilateral papillary necrosis with blunting of the calyces (short arrow), formation of clefts at the renal pyramid (long arrow) and filling defects within the calyces (curved arrow). Coronal sections through the kidneys in (b) show a cleft (curved arrow) at the left upper polar calyx with filling defects in the upper pole calyces of both kidneys (small white arrows). (c) Shows a lower pole calyx filled with slough also known as phantom calyx (straight arrow). A cleft is also noted (curved arrow).
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Evaluation by MRI additionally showed filling defects in the calyces of both kidneys (Figure 9). Urine culture demonstrated the growth of Escherichia coli (Figure 9).
(a-d) (Same patient as in Figure 9) (a, b) Coronal and axial T2 weighted images of the left kidney shows irregular calyces with blunting, with intermediate signal intensity in the left lower pole (small arrow). (c) Shows true diffusion restriction of a thin rim of renal parenchyma on the right side (short white arrow) and true diffusion restriction of the calyces on the left side (long white arrow). Subtle diffusion restriction was noted in the calyces of the right kidney (curved arrow). Corresponding apparent diffusion coefficient hypointensity was noted in both kidneys [b = 0, 800 s mm-2, TR 4500 ms, TE 90 ms ET = 1]. Apparent diffusion coefficient value derived at the calyces of the left kidney was 0.989x 10-3 mm2 s-1.
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Further, the right kidney showed a thin rim of parenchymal diffusion restriction with diffusion restriction of the calyces and the tip of the medullary pyramids in both kidneys (Figure 10).