Diagnosis of acute pyelonephritis by contrast-enhanced ultrasonography in kidney transplant patients.
BACKGROUND
Diagnostic imaging of acute pyelonephritis (APN) in renal transplanted patients is an important clinical issue. While conventional ultrasonography (US) has a limited diagnostic role, contrast-enhanced computer tomography and magnetic resonance imaging (MRI) represent the gold standard diagnostic tests. However, nephrotoxicity of either iodinated or paramagnetic contrast medium limits their use, especially in patients with kidney disease. Contrast-enhanced US (CEUS) may detect poorly perfused parenchymal renal areas, a useful feature in the diagnosis of APN. The aim of this study was to evaluate the diagnostic value of CEUS in APN compared with MRI as the reference test.


METHODS
From a pool of 389 kidney transplant patients, we prospectively recruited 56 patients with clinical suspicion of APN of the transplanted kidney. They underwent both CEUS and MRI, performed in a blinded manner by two different operators. Sensitivity, specificity, accuracy, positive and negative predictive values, and K statistics were calculated.


RESULTS
Thirty-seven out of 56 patients (66.1%) resulted positive for APN with the reference test, gadolinium-enhanced MRI. Thirty-five out of these 37 patients showed positive results for APN with CEUS, and 19 patients showed negative results for APN with both MRI and CEUS: sensitivity 95% (CI 82-99), specificity 100% (CI 83-100), accuracy 96% (CI 88-99), positive predictive value 100% (CI 90-100), negative predictive value 90% (CI 71-97) and K statistics 0.92 (P<0.01).


CONCLUSIONS
Our results suggest, for the first time, the feasibility of CEUS, a low-cost and low-risk diagnostic procedure, in the diagnosis of APN in kidney transplant patients.
Granata
Antonio
A
Department of Nephrology, AOU Policlinico-Vittorio Emanuele Catania, Italy. antonio.granata4@tin.it
Andrulli
Simeone
S
Fiorini
Fulvio
F
Basile
Antonio
A
Logias
Francesco
F
Figuera
Michele
M
Sicurezza
Elvia
E
Gallieni
Maurizio
M
Fiore
Carmelo Erio
CE
D000208:Acute Disease; D000328:Adult; D003287:Contrast Media; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging*; D016030:Kidney Transplantation / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011704:Pyelonephritis / Q000000981:diagnostic imaging*; D014463:Ultrasonography
D003287:Contrast Media