Ultrasonography of the Kidney: A Pictorial Review

Abstract

Ultrasonography of the kidneys is essential in the diagnosis and management of kidney-related diseases. The kidneys are easily examined, and most pathological changes in the kidneys are distinguishable with ultrasound. In this pictorial review, the most common findings in renal ultrasound are highlighted.

Keywords: pictorial review; practical guide; renal ultrasound.

Figure 1

Normal adult kidney. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line. * Column of Bertin; ** pyramid; *** cortex; **** sinus.

Figure 2

Normal pediatric kidney. * Column of Bertin; ** pyramid; *** cortex; **** sinus.

Figure 3

Measures of the kidney. L = length. P = parenchymal thickness. C = cortical thickness.

Figure 4

Doppler ultrasound (US) of a normal adult kidney with the estimation of the systolic velocity (Vs), the diastolic velocity (Vd), acceleration time (AoAT), systolic acceleration (Ao Accel) and resistive index (RI). Red and blue colors in the color box represent flow towards and away from the transducer, respectively. The specrogram below the B-mode image shows flow velocity (m/s) against time (s) obtained within the range gate. The small flash icons on the spectrogram represent initiation of the flow measurement.

Figure 5

Simple cyst with posterior enhancement in an adult kidney. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Figure 6

Complex cyst with thickened walls and membranes in the lower pole of an adult kidney. Measurements of kidney length and the complex cyst on the US image are illustrated by ‘+’ and dashed lines.

Figure 7

Advanced polycystic kidney disease with multiple cysts.

Figure 8

Cortical solid mass, which later was shown to be renal cell carcinoma. Measurement of the solid mass on the US image is illustrated by ‘+’ and a dashed line.

Figure 9

Renal cell carcinoma with both cystic and solid components located in the cortex. Measurement of tumor on the US image is illustrated by ‘+’ and a dashed line.

Figure 10

Solid tumor in the renal sinus seen as a hypoechoic mass, later found to be lymphoma. The ‘1’ and ‘2’ on the US image are reference points used for CT fusion (not shown).

Figure 11

Angiomyolipoma seen as a hyperechoic mass in the upper pole of an adult kidney.

Figure 12

Patient with tuberous sclerosis and multiple angiomyolipomas in the kidney. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Figure 13

Hydronephrosis due to ureteropelvic junction obstruction in a pediatric patient.

Figure 14

Bilateral dilatation of the ureters due to vesicoureteric reflux in a pediatric patient.

Figure 15

End-stage hydronephrosis with cortical thinning. Measurement of pelvic dilatation on the US image is illustrated by ‘+’ and a dashed line.

Figure 16

Hydronephrosis with dilated anechoic pelvis and calyces, along with cortical atrophy. The width of a calyx is measured on the US image in the longitudinal scan plane, and illustrated by ‘+’ and a dashed line.

Figure 17

Same patient as in Figure 16 with measurement of the pelvis dilation in the transverse scan plane illustrated on the US image with ‘+’ and a dashed line.

Figure 18

Renal stone located at the pyeloureteric junction with accompanying hydronephrosis.

Figure 19

Centrally-located stone with posterior shadowing. No hydronephrosis is present. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Figure 20

Staghorn calculi filling the entire collecting system and creating pronounced shadowing.

Figure 21

Left hydroureter with ureteric jet. No stone is visible. The red color in the color box represents motion towards the transducer as defined by the color bar.

Figure 22

Chronic renal disease caused by glomerulonephritis with increased echogenicity and reduced cortical thickness. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Figure 23

Nephrotic syndrome. Hyperechoic kidney without demarcation of cortex and medulla.

Figure 24

Chronic pyelonephritis with reduced kidney size and focal cortical thinning. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Figure 25

End-stage chronic kidney disease with increased echogenicity, homogenous architecture without visible differentiation between parenchyma and renal sinus and reduced kidney size. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Figure 26

Acute pyelonephritis with increased cortical echogenicity and blurred delineation of the upper pole.

Figure 27

Postoperative renal failure with increased cortical echogenicity and kidney size. Biopsy showed acute tubular necrosis.

Figure 28

Renal trauma with laceration of the lower pole and subcapsular fluid collection below the kidney.

Figure 29

(A) Percutaneous nephrostomy tube placed through a calyx in the lower pole of a kidney with hydronephrosis. (B) The pigtail catheter is placed in the dilated calyx. The tube in (A) and the pigtail in (B) are marked with white arrows.

Figure 30

Renal cell carcinoma successfully treated with thermal ablation, as no contrast enhancement is seen.

Figure 31

Unspecific cortical lesion on CT is confirmed cystic and benign with contrast-enhanced ultrasound (CEUS) using image fusion.

Figure 32

Strain elastography of a normal kidney. Red depicts soft areas, and blue depicts hard areas relative to the entire elastography image. Note that the medulla is softer than the cortex. A color bar is shown to the left of the image, where ‘S’ and ‘H’ denote soft and hard tissue, respectively.