Classic Signs in Uroradiology1
See the questionnaire on pp S281–S288.
Raymond B. Dyer, MD ● Michael Y. Chen, MD ● Ronald J. Zagoria, MD The language of radiology is rich with descriptions of imaging ﬁndings, often metaphorical, which have found common usage in the day-to-day practice of genitourinary radiology. These “classic signs” give usconﬁdence in our diagnosis. Some of the signs have become so familiar to us that they are referred to as an “Aunt Minnie.” When the sign is invoked, or an Aunt Minnie is recognized, it often brings an impression of the image to mind, and it may have speciﬁc diagnostic and pathologic implications. The article uses classic signs accumulated from the literature to review a variety of pathologic conditions inthe urinary tract.
LEARNING OBJECTIVES FOR TEST 6
After reading this article and taking the test, the reader will be able to: Recognize radiologic signs associated with urinary tract disease. Describe the pathophysiologic characteristics associated with the radiologic ﬁndings. Apply the illustrated signs across imaging modalities.
Index terms: Genitourinary system, CT,80.1211 ● Genitourinary system, MR, 80.12141 ● Genitourinary system, radiography, 80.122, 80.123 Genitourinary system, US, 80.1298 RadioGraphics 2004; 24:S247–S280 ● Published online 10.1148/rg.24si045509 ● Content Code:
the Department of Radiology, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157. Recipient of a Certiﬁcate of Merit award for aneducation exhibit at the 2003 RSNA scientiﬁc assembly. Received February 17, 2004; revision requested March 9 and received March 29; accepted May 12. All authors have no ﬁnancial relationships to disclose. Address correspondence to R.B.D. (e-mail: email@example.com). RSNA, 2004
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Figures 1, 2. (1a) Staghorns. (1b) On a scout imageobtained before excretory urography, a calculus ﬁlls nearly the entirety of a biﬁd right renal collecting system, giving it a branched appearance that resembles the antlers of a stag. (2a) Scout radiograph obtained before excretory urography demonstrates disruption of the elements of a staghorn calculus—a fragmented staghorn—in an enlarged right kidney. (2b) Excretory urogram shows no evidence ofcontrast material excretion from the right kidney. Renal enlargement, presence of an obstructing stone, and absence of excretion are considered the classic imaging triad of xanthogranulomatous pyelonephritis.
Descriptions of observations made from images are the radiologist’s stock in trade. Because we “see what we know,” any device that aids in the recognition and interpretation ofimaging ﬁndings is useful. The article reviews “classic signs,” often
referred to as an “Aunt Minnie,” encountered in the urinary tract.
Staghorn and Related Signs
A renal stone described as a staghorn implies a branched renal calculus that resembles the antlers of a stag (Fig 1). It is usually composed of struvite; but less commonly, it is formed from cystine
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Dyer et al
Figure 3. (a) A bear’s paws. (Photograph entitled “Bad Boys of the Arctic” reprinted with permission from Thomas D. Mangelsen, Inc.) (b) Contrast material– enhanced CT scan (same patient as in Fig 2) demonstrates a centrally obstructing stone with replacement of the renal parenchyma by low-attenuation collections in a “hydronephrotic” pattern. Note the lack ofdilatation of the renal pelvis and infundibula. (c) CT scan obtained at a slightly lower level shows the fragments of a staghorn calculus within the parenchymal collections, which exhibit marginal enhancement. The pattern seen at CT resembles a bear’s paw.
or uric acid. In its most common form, a staghorn renal stone is associated with recurrent urinary tract infections from bacterial...