MRI and suspected acute pyelonephritis in children: comparison of diffusion-weighted imaging with gadolinium-enhanced T1-weighted imaging

Objectives

To evaluate the performance of diffusion-weighted imaging (DWI) against the reference standard of gadolinium-enhanced T1-weighted imaging (Gd-T1-WI) in children.

Methods

Thirty-nine consecutive patients (mean age 5.7 years) with suspected acute pyelonephritis underwent magnetic resonance imaging (MRI) including DWI and (the reference standard) Gd-T1-WI. Each study was read in double-blinded fashion by two radiologists. Each kidney was graded as normal or abnormal. Sensitivity and specificity of DWI were computed. Agreement between sequences and interobserver reproducibility were calculated (Cohen κ statistic and the McNemar tests).

Results

Thirty-two kidneys (41 %) had hypo-enhancing areas on Gd-T1-W images. The sensitivity and specificity of DWI were 100 % (32/32) and 93.5 % (43/46). DWI demonstrated excellent agreement (κ?=?0.92,) with Gd-T1-W, with no significant difference (P?=?0.25) in detection of abnormal lesions. Interobserver reproducibility was excellent with DWI (κ?=?0.79).

Conclusion

DWI enabled similar detection of abnormal areas to Gd-T1-WI and may provide an injection-free means of evaluation of acute pyelonephritis.

Key points

? Diffusion weighted magnetic resonance imaging (DWI) can confirm acute pyelonepritis. ? DWI provided comparable results to gadolinium enhanced T1-W MRI in acute pyelonepritis. ? Contrast medium injection could be avoided for diagnosing acute pyelonephritis by MRI. ? MRI with T2-WI and DWI provide a fast and comprehensive diagnostic tool.