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

Abstract

Purpose: To assess reliability of diffusion-weighted magnetic resonance imaging (DW-MRI) in the management of acute pyelonephritis (APN) foci in transplanted kidneys. Materials and methods: In the 2012-2014 period, 24 kidney-transplanted patients underwent MR screening for clinical suspicion of APN. Two readers independently analyzed all images, establishing presence and location of APN foci. The 22 patients who were positive at the MR exam constituted the study population. For each patient the apparent diffusion coefficient (ADC) was measured in the APN foci and in three sites of the healthy parenchyma (case-control comparison). The data were matched to the laboratory measurements for white blood cell, C-reactive protein, and serum creatinine. Results: Forty-six APN foci were found in 22/24 patients. At the acute stage, the difference in ADC between healthy parenchyma and APN foci was significant (2.06 ± 0.16 vs. 1.43 ± 0.32 9 10 -3 mm 2 /s; p < 0.0001). The performance of ADC as APN indicator was tested by the receiving operating characteristics (ROC) curve: the area under curve AUC = 0.99 witnessed an excellent discriminatory ability, with threshold APN/normal parenchyma 1.9 9 10 -3 mm 2 /s. At the 1-month follow-up 43/46 APN foci were no longer visible, with ADC values significantly higher than at the acute stage; all laboratory data were physiological, with WBC significantly reduced from the acute phase (5.2 ± 1.6 9 10 9 /L vs. 10.6 ± 4.8 9 10 9 /L; p < 0.0001). The other 3 patients underwent further therapy and exams, including a third MR.Conclusions: DW-MRI with ADC measurement seems to be a reliable tool in diagnosing and monitoring APN foci in transplanted kidneys, with clinical impact on patient management.

Integrating MRI and Chemokine Receptor CXCR4-Targeted PET for Detection of Leukocyte Infiltration in Complicated Urinary Tract Infections After Kidney Transplantation

“…In particular, tracer accumulation in parts of the renal pelvis may be easily differentiated from cortical uptake using T2weighted MR sequences. Diffusion-weighted MRI has high sensitivity to detect areas of restricted diffusion in renal parenchyma indicating pyelonephritis (15). In particular, MRI facilitates the discrimination of foci with leukocyte infiltration from normal parenchyma because the range of ADC values in normal parenchyma is narrow and, in contrast to SUVs, there is no overlap for ADC min and only little overlap for ADC mean between foci and parenchyma ( Fig.…”

“…68 Ga-pentixafor has also been reported to specifically identify postinfarction myocardial inflammation mediated by CXCR4 1 leukocytes (13) and atherosclerotic plaque inflammation (14). Diffusion-weighted MRI has been shown to provide useful information for diagnosing and monitoring pyelonephritis foci in transplanted kidneys (15). MRI-derived apparent diffusion coefficients (ADCs) are inversely correlated with inflammatory cell infiltration in the kidneys (16).…”

MRI for diagnosis of post-renal transplant complications: current state-of-the-art and future perspectives

“…Areas without any signal abnormalities were considered to be healthy renal tissue. In the acute phase, ADC difference was significant between affected and unaffected tissue and showed excellent discriminatory ability [85]. Other studies confirm the ability of DWI and DTI to detect renal infection in kidneys and diffusion parameters could play an important role in monitoring treatment effectiveness [85][86][87][88].…”

ACR Appropriateness Criteria® Acute Pyelonephritis

“…Vivier et al [21] found DWI and contrast-enhanced MRI to be of equivalent value in a study of pediatric patients. Several studies in adults have shown DWI to be useful in diagnosing uncomplicated pyelonephritis [19,[22][23][24]. One study by Rathod et al [19] found a higher sensitivity of DWI (95%) compared with noncontrast CT (67%) and contrast-enhanced CT (88%) in the diagnosis of pyelonephritis.…”