MR diffusion-weighted imaging of kidney: differentiation between hydronephrosis and pyonephrosis

Area of Science:

• Radiology
• Medical Imaging
• Nephrology

Background:

• Hydronephrosis and pyonephrosis are distinct kidney conditions often requiring accurate differentiation for appropriate treatment.
• Ultrasonography (US) can detect renal pelvis and calyceal dilatation, but differentiating the underlying cause can be challenging.

Purpose of the Study:

• To assess the efficacy and dependability of magnetic resonance (MR) diffusion-weighted imaging (DWI) in distinguishing between hydronephrosis and pyonephrosis.
• To evaluate the role of apparent diffusion coefficient (ADC) values in this differentiation.

Main Methods:

• Single-shot echoplanar MR DWI was performed on 12 patients with suspected renal pelvic dilatation.
• Signal intensities of the pelvicalyceal systems were analyzed on DWI and ADC maps.
• ADC values were computed and compared between hydronephrotic and pyonephrotic kidneys using Student's t test.

Main Results:

• Pelvicalyceal systems showed hypointensity on DWI in hydronephrosis and marked hyperintensity in pyonephrosis.
• Mean ADC values were significantly lower in pyonephrotic kidneys (0.64 x 10(-3) mm(2)/s) compared to hydronephrotic kidneys (2.98 x 10(-3) mm(2)/s).
• Low ADC values in pyonephrosis correlated with hyperintensity on DWI and hypointensity on ADC maps.

Conclusions:

• MR DWI is a reliable imaging tool for differentiating pyonephrosis from hydronephrosis.
• ADC values provide a quantitative measure that aids in distinguishing these two conditions.
• This technique can improve diagnostic accuracy in patients with dilated renal collecting systems.