Diffusion-weighted magnetic resonance imaging: new perspectives in the diagnostic pathway of non-complicated acute pyelonephritis
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The diagnosis of acute pyelonephritis (APN) requires demonstration of parenchymal involvement. When no predisposing conditions are found, non-complicated APN is suspected and CT or MRI should be performed. Diffusion-weighted (DW) MRI might be useful, quicker and cheaper than the standard gadolinium-enhanced (GE) MRI. The aim of this study is to compare DW-MRI with GE-MRI to test its diagnostic accuracy in APN.
Of 318 consecutive patients hospitalised for APN, 279 underwent MRI. Four hundred and fourteen MR studies (first test and follow-up examinations) were gathered and data were processed using Diffusion Analysis software. DW-MRI has been compared with GE-MRI for evaluating diagnostic agreement.
Two hundred and forty-four patients were diagnosed as having APN; 35 were negative. One hundred and sixty-three APN cases were considered non-complicated and selected for the study. Among the 414 MR examinations, comparing DW-MRI with GE-MRI, positive correlation was found in 258 cases, negative in 133. There were 14 false-negatives and 9 false-positives. DW-MRI achieved sensitivity 95.2 %, specificity 94.9 %, positive predictive value 96.9 %, negative predictive value 92.3 % and accuracy 94.6 %.
DW-MRI is reliable for diagnosing non-complicated APN. The high diagnostic agreement between DW-MRI and GE-MRI offers new perspectives in diagnostic management, enabling diagnosis of non-complicated APN without using ionising radiation or contrast media.
• The diagnosis of acute pyelonephritis (APN) requires demonstration of renal involvement.
• Hitherto magnetic resonance imaging required gadolinium enhancement (GE-MRI) to establish this diagnosis.
• But diagnostic agreement between diffusion-weighted and GE-MRI offers new diagnostic opportunities.
• Quantification of ADC values can help diagnose and monitor APN.
• DW-MRI avoids ionising radiation and paramagnetic contrast medium administration.
KeywordsAcute pyelonephritis Urinary tract infections Gadolinium-enhanced magnetic resonance imaging Diffusion-weighted magnetic resonance imaging Apparent diffusion coefficient
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