Which of the following is not seen in imaging of acute pyelonephritis?

Ref: Cavorsi A'. Prabhakar P, Kirby C. Acute pyelonephritis. Ultrasound Q 2010;26(2): 103-5 ami Ultrasound: A Practical Approach to Clinical Problems, Edited by Edward I. Bluth, Page 465 and Genitourinary Imaging by Shailendra Chopra, Thieme PublishersExplanation:"The affected kidney is enlarged, areas of relative ischemia develop within the kidney increased intraparenchymal pressure. Perinephric edema maybe present." Ref: Genitourinary ImagingACUTE PYELONEPHRITISDiagnosis of acute pyelonephritis is made with clinical and laboratory findings.Imaging is required only ino Atypical presentationso Complications.o Inadequate response to therapy.Ultrasound is insensitive to the changes of acute pyelonephritis, with most patients having 'normal' scan, and abnormalities only identified in 20-24% of cases, especially in severe cases.Possible Ultrasound Features include Features of Acute PyelonephritisDiffuse renal enlargement.Loss of corticomedullary differentiation.Submucosal edema of renal pelvis/ureter.Calyceal/Pelvic/ureterul dilatation.Particulate matter in the collecting system.Gas bubbles (Emphysematous pyelonephritis).Abnormal echogenicity of the renal parenchyma:o Focal/Segmental hypoechoic/hyperechotc regions.o Diffuse or focal enlargement of the kidney (Rarely 'mass' like lesion)o Wedge or round shaped.Note:Color Doppler typically shows decreased perfusion in the affected parenchyma, which is due to arteriolar vasoconstriction and interstitial edema.CECT is more accurate in detecting changes of pyelonephritis than conventional sonography.