Experimental pyelonephritis in piglets: diagnosis with MR imaging.
OBJECTIVE
To compare findings at magnetic resonance (MR) imaging with those at histopathologic examination in the detection of experimentally induced pyelonephritis in piglets.


METHODS
MR imaging was performed in 23 piglets with and nine piglets without experimentally induced pyelonephritis. Escherichia coli were injected into the bladder of the 23 piglets with surgically created vesicoureteral reflux. Imaging was performed with unenhanced and contrast material-enhanced T1-weighted and fast multiplanar inversion-recovery (IR) and fast spinecho T2-weighted sequences. MR images and pathologic findings were reviewed independently by two pediatric radiologists and a pathologist, respectively, in a blinded fashion.


RESULTS
Sixty-four kidneys and 192 renal zones were evaluated. Coronal gadolinium-enhanced fast multiplanar IR imaging was the only sequence that was sensitive and specific for 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 pathologically negative zones. Findings at gadolinium-enhanced fast multiplanar IR imaging were not statistically different from findings at histopathologic examination in the detection of pyelonephritis. Interobserver reproducibility for the contrast-enhanced fast multiplanar IR sequence was excellent (kappa statistic = 0.82 and 0.90, respectively, for interpretation of a renal zone and of a kidney).


CONCLUSIONS
Contrast-enhanced fast multiplanar IR imaging is a sensitive and specific test for detection of experimental pyelonephritis in this piglet model.
Pennington
D J
DJ
Department of Radiology, PSRD, Wilford Hall U.S. Air Force Medical Center, Lackland Air Force Base, TX 78236-5300, USA.
Lonergan
G J
GJ
Flack
C E
CE
Waguespack
R L
RL
Jackson
C B
CB
D000818:Animals; D003287:Contrast Media; D004338:Drug Combinations; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D019786:Gadolinium DTPA; D007668:Kidney / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008536:Meglumine; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives; D011237:Predictive Value of Tests; D011704:Pyelonephritis / Q000175:diagnosis* / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
D003287:Contrast Media; D004338:Drug Combinations; D009942:Organometallic Compounds; D008536:Meglumine; D004369:Pentetic Acid; D019786:Gadolinium DTPA