Abstract:
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Purpose: To evaluate the potentials of contrast-enhanced US (CEUS) for the
diagnosis of acute pyelonephritis (APN) in renal transplants using quantitative
measurements.
Methods and Materials: 37 renal transplants (22 women, 15 men) with clinical
and biological suspicion of acute pyelonephritis were prospectively studied
using B mode, color and power Doppler imaging, harmonic SonoCT, and
intermittent pulse inversion before and after administration of Levovist
(Schering AG, Germany) with an HDI5000 (Philips, Bothell, USA, C5-2). CEUS was
performed before the correlative imaging obtained from contrast-enhanced CT (35
cases) and MRI (2 cases). Cineloops were stored under proprietary format that
allows review and quantification using HDI Lab software (Philips). The final
diagnosis of APN resulted from a clinical and radiological consensus (28 APN, 9
other diseases). The contrast ratio of the infected areas was defined using a
region-of-interest (ROI) as the absolute difference in linear units between the
diseased area and the surrounding cortex, before and until disappearance of the
contrast enhancement
Results: Color and Power Doppler imaging did not allow identification of the
infected parenchyma, due to the heterogeneity of the cortical perfusion. Normal
cortex strongly enhanced during early vascular phase (10.5 +/- 4.5 dB). Acute
focal nephritis exhibited a triangular shape and was seen in 72% of the cases
on B mode and as triangular defects in 95% of the cases after injection. The
contrast ratio between infected and surrounding parenchyma was 4.4 +/- 6.5 dB
during early vascular phase, 5.5 +/- 6.5 dB during parenchymal phase and 3.3
+/- 5.6 dB during delayed phase. 12 abscesses were detected without contrast
and all abscesses were seen after Levovist injection (n = 23).
Conclusion: CEUS improves the diagnosis of APN in renal transplants and allows
detection of all abscesses. However, many artifacts due to the heterogeneity of
the enhancement should be identified to avoid misdiagnosis. (J.C. is a member
of the scientific advisory board of Philips US, Bothell, WA.)
Duval, A,
The Diagnosis of Acute Pyelonephritis in Renal Transplants Using Contrast-enhanced US. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102283.html
