Diffusion weighted MR imaging in the diagnosis of acute pyelonephritis and its complications: A prospective observational study

Abstract

Introduction: In diagnosing complicated pyelonephritis, imaging is essential for which traditionally computed tomography (CT) has been in use but in renal failure patients contrast enhanced CT can't be performed due to elevated serum creatine levels. This can be overcome with the help of Diffusion weighted (DW) magnetic resonance imaging (MRI). Purpose: To assess the morphological changes and signal abnormalities, in kidneys in patients with acute pyelonephritis (APN) on conventional MRI and DWI and to measure the ADC values in areas of abnormal signal intensity in DWI so as to differentiate between abscess and nephritis. Materials and Methods: In our study, 32 patients with clinical and laboratory diagnosis of pyelonephritis underwent conventional and Diffusion weighted MRI. Diffusion images were obtained by using a non-breath-hold, single-shot echo-planar sequence with b values of 50/400/800 s/mm2. Circular regions of interest were drawn in the areas of normal renal parenchyma, nephritis and abscesses. The ADC values of three tissue types were compared by using the paired t-test and ANOVA.P value < 0.001 was considered to be statistically significant. Results: In our study, areas of normal renal parenchyma showed ADC values of (1.83 ± 0.06) × 10-3 mm2/s while areas of nephritis had ADC values of (1.20 ± 0.08) × 10-3 mm2/s which was significantly lower (P < 0.001). Also, significantly lower ADC values of (0.77 ± 0.05) × 10-3 mm2/s were found in abscesses, when compared to nephritis and normal renal parenchyma. Conclusion: Diffusion weighted MR imaging is useful to diagnose abscess formation in patients with pyelonephritis without using IV contrast medium.

Keywords

• abscess
• acute pyelonephritis
• diffusion weighted mr imagin