Brian Stephen Garra MD, Presenter: Nothing to Disclose

Daniel N. Sommers MD, Abstract Co-Author: Nothing to Disclose

John Doherty, Abstract Co-Author: Nothing to Disclose

Stephen Fath, Abstract Co-Author: Nothing to Disclose

Elisabeth Jannicky BA, Abstract Co-Author: Nothing to Disclose

To evaluate the usefulness of speckle reduction imaging (SRI) and spatial compounding for the diagnosis of focal pyelonephritis when using fundamental and harmonic grayscale imaging.

15 patients having focal pyelonephritis on contrast enhanced CT scans were examined using a 3.5MHz or 5MHz curved array transducer using both fundamental and harmonic imaging with and without speckle reduction. If spatial compounding was available, additional images were taken with it set to an intermediate value of speckle reduction. All images were later reprocessed using SRI either on the scanner itself or off line on a LOGIQworks (GE Ultrasound) workstation. Two observers (one sonologist and one sonographer) then viewed the images and were asked to identify areas of increased or decreased echogenicity denoting focal pyelonephritis, scoring their confidence for the diagnosis on a 10 point scale. The results for speckle reduced images were compared to the standard images using CT as ground truth. Areas were recorded as true positives if both the diagnosis and quadrant of involvement (anterior or posterior and upper or lower) were correct. These data were acquired so that later ROC analysis could be performed.

Focal pyelonephritis appeared as areas of increased or decreased echogenicity--often associated with focal swelling of the affected renal cortex producing increased thickness or a contour abnormality of the kidney. The changes were seen with much greater confidence using speckle reduction. Often a combination of harmonic imaging and speckle reduction resulted in the greatest conspicuity of the abnormalities but on occasion, fundamental imaging plus SRI was more effective, especially with hypoechoic lesions. Careful scanning to avoid artifactual changes in echogenicity caused by shadowing from superficial structures was necessary.

Speckle reduction technologies have the potential to greatly increase the sensitivity of US for the diagnosis of pyelonephritis. Further studies on kidneys without infection are needed to determine what other entities might produce similar changes in the renal parenchyma.

B.S.G.: Author serves on a speakers' Bureau for GE ultrasound Author has research equipment on loan from GE ultrasound

Garra, B, Sommers, D, Doherty, J, Fath, S, Jannicky, E, The Value of Speckle Reduction Technology for Increasing the Detectability of Focal Pyelonephritis.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4413360.html