Imaging of acute pyelonephritis in the adult

Abstract

The diagnosis of acute pyelonephritis in adults is predominantly made by a combination of typical clinical features of flank pain, high temperature and dysuria combined with urinalysis findings of bacteruria and pyuria. Imaging is generally reserved for patients who have atypical presenting features or in those who fail to respond to conventional therapy. In addition, early imaging may be useful in diabetics or immunocompromised patients. In such patients, imaging may not only aid in making the diagnosis of acute pyelonephritis, but more importantly, it may help identify complications such as abscess formation. In this pictorial review, we discuss the role of modern imaging in acute pyelonephritis and its complications. We discuss the growing role of cross-sectional imaging with computed tomography (CT) and novel magnetic resonance imaging (MRI) techniques that may be used to demonstrate both typical as well as unusual manifestations of acute pyelonephritis and its complications. In addition, conditions such as emphysematous and fungal pyelonephritis are discussed.

Acute pyelonephritis in transplanted kidneys: can diffusion-weighted magnetic resonance imaging be useful for diagnosis and follow-up?

“…Our results showed that the 46 inflammatory foci had statistically lower ADC values (1.43 ± 0.32 9 10 -3 mm 2 /s) than healthy parenchyma, as measured in the 22 patients with suspected APN (2.06 ± 0.16 9 10 -3 mm 2 /s) and in the 26 patients without suspected APN (1.99 ± 0.14 9 10 -3 mm 2 /s). The ADC ability to identify APN foci in transplanted kidneys, as estimated by the ROC curve, was excellent (95% CI for AUC 0.995-1), determining ADC < 1.9 9 10 -3 mm 2 /s as the region typical of APN foci (PPV = 94% and NPV = 100%) The role of diagnostic imaging in confirming a clinical suspicion of APN and its impact on treatment decisions has been reported by several studies [14][15][16][17][18][19]. In particular it was also emphasized that imaging is indispensable for confirming treatment effectiveness during follow-up [20].…”

Sepsis due to pyonephrosis: an adult with pelvic–ureteric junction obstruction (PUJO) in a duplex kidney

“…Ultrasound can be helpful in identifying the source of infection [8][9][10][11]; it can help define and monitor the hemodynamic status of the patient via evaluation of inferior vena cava, heart and lung water [12][13][14]; it can guide invasive procedures in both diagnosis (sampling) and treatment (drainage) [15].…”

Urinary Obstruction, Stone Disease, and Infection

“…• To review the pathogenesis of urinary infection, obstruction, and stones • To discuss the imaging features of acute urologic infections such as renal abscess, acute pyelonephritis, and emphysematous pyelonephritis or chronic infections such as renal tuberculosis • To illustrate the imaging of struvite or infection stones as well as highlight their complications only 20% of patients [2,3]. However, new techniques such as tissue harmonics have showed sensitivity and specificity of 97% and 80% [3].…”

“…Following intravenous contrast administration, pyelonephritis manifests as "wedge shaped" or linear regions of decreased enhancement that spans from the renal sinus to the renal cortex. The excretory phase, obtained between 3 and 5 min after the administration of contrast, should be performed in suspected urinary obstruction [2]. CT also can evaluate for additional features of renal inflammation and its complications, including inflammation of the perinephric fat, thickening of Gerota's fascia, and abscess formation.…”

“…The most common inciting organisms are E. coli and Proteus mirabilis which are organisms associated with struvite/infection stones. XGPN classically presents in mid-aged female patients with recurrent urinary tract infection, diabetes, or obstructing urinary stones [2,5]. XGPN may involve the entire kidney (diffuse) or related to an obstructed upper or lower pole (focal), which at times is difficult to differentiate from tumor or abscess.…”