EXPERIMENTAL PYELONEPHRITIS IN PIGLETS - DIAGNOSIS WITH MR-IMAGING

PURPOSE: To compare findings at magnetic resonance (MR) imaging with t hose at histopathologic examination in the detection of experimentally induced pyelonephritis in piglets. MATERIALS AND METHODS: MR imaging was performed in 23 piglets with and nine piglets without experimental ly induced pyelonephritis. Escherichia coli were injected into the bla dder of the 23 piglets with surgically created vesicoureteral reflux. Imaging was performed with unenhanced and contrast material-enhanced T 1-weighted and fast multiplanar inversion-recovery (IR) and fast spin- echo 2-weighted sequences. MR images and pathologic findings were revi ewed independently by two pediatric radiologists and a pathologist, re spectively, in a blinded fashion. RESULTS: Sixty-four kidneys and 192 renal zones were evaluated, Coronal gadolinium-enhanced fast multiplan ar IR imaging was the only sequence that was sensitive and specific fo r the diagnosis of pyelonephritis. For the two reviewers, respectively , sensitivity was 85% (n=75) and 92% (n=81) of 88 histopathologically positive zones and specificity was 95% (n=99) and 94% (n=98) of 104 pa thologically negative zones. Findings at gadolinium-enhanced fast mult iplanar IR imaging were not statistically different from findings at h istopathologic examination in the detection of pyelonephritis. Interob server reproducibility for the contrast-enhanced fast multiplanar IR s equence was excellent (kappa statistic=0.82 and 0.90, respectively, fo r interpretation of a renal zone and of a kidney). CONCLUSION: Contras t-enhanced fast multiplanar IR imaging is a sensitive and specific tes t for detection of experimental pyelonephritis in this piglet model.