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Classic Signs in Uroradiology¹

¹ From 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 an education 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: rdyer@wfubmc.edu).

View larger version (148K): [in a new window]   Figure 1a.  (a) Staghorns. (b) On a scout image obtained 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.

View larger version (138K): [in a new window]   Figure 1b.  (a) Staghorns. (b) On a scout image obtained 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.

View larger version (138K): [in a new window]   Figure 2a.  (a) Scout radiograph obtained before excretory urography demonstrates disruption of the elements of a staghorn calculus—a fragmented staghorn—in an enlarged right kidney. (b) Excretory urogram shows no evidence of contrast 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.

View larger version (136K): [in a new window]   Figure 2b.  (a) Scout radiograph obtained before excretory urography demonstrates disruption of the elements of a staghorn calculus—a fragmented staghorn—in an enlarged right kidney. (b) Excretory urogram shows no evidence of contrast 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.

View larger version (118K): [in a new window]   Figure 3a.  (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 of dilatation 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.

View larger version (140K): [in a new window]   Figure 3b.  (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 of dilatation 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.

View larger version (145K): [in a new window]   Figure 3c.  (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 of dilatation 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.

View larger version (139K): [in a new window]   Figure 4a.  (a) Jacks. (b) Scout radiograph shows a jack stone with long spikes that has formed within the kidney.

View larger version (119K): [in a new window]   Figure 4b.  (a) Jacks. (b) Scout radiograph shows a jack stone with long spikes that has formed within the kidney.

View larger version (106K): [in a new window]   Figure 5.  Scout radiograph of a mulberry stone shows its less well-developed spikes, which give it a mamillated appearance, resembling a mulberry.

View larger version (108K): [in a new window]   Figure 6a.  (a) "Sponge" kidney, made from a sponge! (b) Scout image from excretory urography demonstrates calcifications clustered in the medullary portion of the left kidney. (c) After contrast material administration, numerous cavities are identified within the renal papilla in the patient with medullary sponge kidney. Some of the calcifications appear to grow, as contrast agent fills the entire cavity containing the stone.

View larger version (92K): [in a new window]   Figure 6b.  (a) "Sponge" kidney, made from a sponge! (b) Scout image from excretory urography demonstrates calcifications clustered in the medullary portion of the left kidney. (c) After contrast material administration, numerous cavities are identified within the renal papilla in the patient with medullary sponge kidney. Some of the calcifications appear to grow, as contrast agent fills the entire cavity containing the stone.

View larger version (110K): [in a new window]   Figure 6c.  (a) "Sponge" kidney, made from a sponge! (b) Scout image from excretory urography demonstrates calcifications clustered in the medullary portion of the left kidney. (c) After contrast material administration, numerous cavities are identified within the renal papilla in the patient with medullary sponge kidney. Some of the calcifications appear to grow, as contrast agent fills the entire cavity containing the stone.

View larger version (128K): [in a new window]   Figure 7a.  (a) Cobwebs. (b) CT scan obtained after extracorporeal lithotripsy reveals a subcapsular hematoma and exaggeration of Kunin septa on the left. Renofascial and renorenal septa are especially well identified. (c) On another CT scan obtained at the lower aspect of the left kidney, fasciofascial septa are nicely seen, and the cobweb appearance is particularly well developed.

View larger version (187K): [in a new window]   Figure 7b.  (a) Cobwebs. (b) CT scan obtained after extracorporeal lithotripsy reveals a subcapsular hematoma and exaggeration of Kunin septa on the left. Renofascial and renorenal septa are especially well identified. (c) On another CT scan obtained at the lower aspect of the left kidney, fasciofascial septa are nicely seen, and the cobweb appearance is particularly well developed.

View larger version (172K): [in a new window]   Figure 7c.  (a) Cobwebs. (b) CT scan obtained after extracorporeal lithotripsy reveals a subcapsular hematoma and exaggeration of Kunin septa on the left. Renofascial and renorenal septa are especially well identified. (c) On another CT scan obtained at the lower aspect of the left kidney, fasciofascial septa are nicely seen, and the cobweb appearance is particularly well developed.

View larger version (122K): [in a new window]   Figure 8a.  (a) One kind of rim (with thanks to Christopher R. Dyer for his assistance with this photograph.) (b) CT scan shows a thin soft-tissue rim (arrow) surrounding a stone impacted in the middle of the left ureter. The rim represents edema of the ureteral wall. The presence of a tissue rim sign allows a confident diagnosis of a stone within the ureter.

View larger version (134K): [in a new window]   Figure 8b.  (a) One kind of rim (with thanks to Christopher R. Dyer for his assistance with this photograph.) (b) CT scan shows a thin soft-tissue rim (arrow) surrounding a stone impacted in the middle of the left ureter. The rim represents edema of the ureteral wall. The presence of a tissue rim sign allows a confident diagnosis of a stone within the ureter.

View larger version (189K): [in a new window]   Figure 9a.  (a) Comet. (Photograph entitled "Comet Hyakutake" reprinted with permission from Bill and Sally Fletcher.) (b) CT scan shows a calcification (the comet nucleus) (arrow) with a soft-tissue tail that represents a pelvic vein (arrowhead). Together, this appearance constitutes the comet sign. Note the stone at the left ureterovesical junction.

View larger version (160K): [in a new window]   Figure 9b.  (a) Comet. (Photograph entitled "Comet Hyakutake" reprinted with permission from Bill and Sally Fletcher.) (b) CT scan shows a calcification (the comet nucleus) (arrow) with a soft-tissue tail that represents a pelvic vein (arrowhead). Together, this appearance constitutes the comet sign. Note the stone at the left ureterovesical junction.

View larger version (149K): [in a new window]   Figure 10a.  Rim sign of vascular compromise. (a) Enhanced CT scan of a motor vehicle accident victim demonstrates no perfusion in the majority of the right kidney. The right renal artery abruptly terminates; this is the arterial cut-off sign (arrowhead). (b) Repeat contrast-enhanced CT scan, obtained 72 hours after a, demonstrates a thin marginal rim of preserved subcapsular enhancement in the left kidney, typical of the rim sign of renovascular compromise. Vascular compromise in this case was caused by intimal injury and thrombosis of the main renal artery.

View larger version (146K): [in a new window]   Figure 10b.  Rim sign of vascular compromise. (a) Enhanced CT scan of a motor vehicle accident victim demonstrates no perfusion in the majority of the right kidney. The right renal artery abruptly terminates; this is the arterial cut-off sign (arrowhead). (b) Repeat contrast-enhanced CT scan, obtained 72 hours after a, demonstrates a thin marginal rim of preserved subcapsular enhancement in the left kidney, typical of the rim sign of renovascular compromise. Vascular compromise in this case was caused by intimal injury and thrombosis of the main renal artery.

View larger version (136K): [in a new window]   Figure 11.  A reverse rim. CT scan, obtained to exclude a large retroperitoneal hematoma in a patient with sustained hypotension for 1 hour after cardiac catheterization and subsequent cardiac arrest, shows a hypoattenuating renal cortex (arrow) compared with the medullary enhancement. No additional contrast material was given after the catheterization. The patient rapidly developed multiorgan failure that led to her death.

View larger version (122K): [in a new window]   Figure 12.  Hydronephrotic rim. CT scan, obtained in a patient with hematuria after minimal trauma, reveals a rim of enhancement surrounding a markedly dilated right renal pelvis and collecting system, findings consistent with congenital ureteropelvic junction obstruction. Note the variable thickness of the enhancing tissue rim (in contrast to the rim sign of vascular compromise [cf Fig 10]), as well as enhancement within cortical columns (arrow).

View larger version (160K): [in a new window]   Figure 13a.  Spotted nephrogram. (a) Spotted cat. (Courtesy of Russell I. Poole, Mishawaka, Ind.) (b) Late image from midstream aortography demonstrates patchy perfusion in both kidneys, giving the parenchyma a spotted appearance: the spotted nephrogram. (c) Late image from selective right renal arteriography in the same patient demonstrates small vessel occlusion and multiple areas of parenchymal infarction (arrow) with islands of preserved perfusion. The patient proved to have periarteritis nodosa.

View larger version (136K): [in a new window]   Figure 13b.  Spotted nephrogram. (a) Spotted cat. (Courtesy of Russell I. Poole, Mishawaka, Ind.) (b) Late image from midstream aortography demonstrates patchy perfusion in both kidneys, giving the parenchyma a spotted appearance: the spotted nephrogram. (c) Late image from selective right renal arteriography in the same patient demonstrates small vessel occlusion and multiple areas of parenchymal infarction (arrow) with islands of preserved perfusion. The patient proved to have periarteritis nodosa.

View larger version (140K): [in a new window]   Figure 13c.  Spotted nephrogram. (a) Spotted cat. (Courtesy of Russell I. Poole, Mishawaka, Ind.) (b) Late image from midstream aortography demonstrates patchy perfusion in both kidneys, giving the parenchyma a spotted appearance: the spotted nephrogram. (c) Late image from selective right renal arteriography in the same patient demonstrates small vessel occlusion and multiple areas of parenchymal infarction (arrow) with islands of preserved perfusion. The patient proved to have periarteritis nodosa.

View larger version (119K): [in a new window]   Figure 14.  Spotted nephrogram. CT scan of another patient with periarteritis nodosa demonstrates the CT correlate of the angiographic findings, with patchy perfusion of the kidneys caused by multiple areas of infarction. (Case courtesy of N. Reed Dunnick, MD, University of Michican Health System, Ann Arbor, Mich.)

View larger version (99K): [in a new window]   Figure 15a.  (a) Crescent. (Photograph entitled "Moon with Earthshine" reprinted with permission from Bill and Sally Fletcher.) (b) Crescent sign. CT image obtained during the corticomedullary phase of enhancement shows decreased thickness of the parenchyma surrounding the dilated collecting system in the left kidney. (c) Concentrated contrast material crescents surround the dilated collecting system elements (arrows) on this delayed image, which also shows a urine-contrast agent level in the dependent aspect.

View larger version (147K): [in a new window]   Figure 15b.  (a) Crescent. (Photograph entitled "Moon with Earthshine" reprinted with permission from Bill and Sally Fletcher.) (b) Crescent sign. CT image obtained during the corticomedullary phase of enhancement shows decreased thickness of the parenchyma surrounding the dilated collecting system in the left kidney. (c) Concentrated contrast material crescents surround the dilated collecting system elements (arrows) on this delayed image, which also shows a urine-contrast agent level in the dependent aspect.

View larger version (149K): [in a new window]   Figure 15c.  (a) Crescent. (Photograph entitled "Moon with Earthshine" reprinted with permission from Bill and Sally Fletcher.) (b) Crescent sign. CT image obtained during the corticomedullary phase of enhancement shows decreased thickness of the parenchyma surrounding the dilated collecting system in the left kidney. (c) Concentrated contrast material crescents surround the dilated collecting system elements (arrows) on this delayed image, which also shows a urine-contrast agent level in the dependent aspect.

View larger version (70K): [in a new window]   Figure 16a.  (a) Balloon on a string (with thanks to Richard T. Dyer for his help with this photograph). (b) Balloon on a string sign. Delayed tomographic image from excretory urography shows caliceal crescents (arrowheads) surrounding the dilated collecting system. Contrast material pools dependently. (c) Image from retrograde ureteropyelography, performed after several weeks of ureteral stent placement, shows an eccentric exit of the ureter from the dilated renal pelvis. This appearance resembles a balloon on a string and is typical of ureteropelvic junction obstruction.

View larger version (80K): [in a new window]   Figure 16b.  (a) Balloon on a string (with thanks to Richard T. Dyer for his help with this photograph). (b) Balloon on a string sign. Delayed tomographic image from excretory urography shows caliceal crescents (arrowheads) surrounding the dilated collecting system. Contrast material pools dependently. (c) Image from retrograde ureteropyelography, performed after several weeks of ureteral stent placement, shows an eccentric exit of the ureter from the dilated renal pelvis. This appearance resembles a balloon on a string and is typical of ureteropelvic junction obstruction.

View larger version (70K): [in a new window]   Figure 16c.  (a) Balloon on a string (with thanks to Richard T. Dyer for his help with this photograph). (b) Balloon on a string sign. Delayed tomographic image from excretory urography shows caliceal crescents (arrowheads) surrounding the dilated collecting system. Contrast material pools dependently. (c) Image from retrograde ureteropyelography, performed after several weeks of ureteral stent placement, shows an eccentric exit of the ureter from the dilated renal pelvis. This appearance resembles a balloon on a string and is typical of ureteropelvic junction obstruction.

View larger version (132K): [in a new window]   Figure 17a.  (a) Target sign (registered trademark of Target, Inc.). (b) T1-weighted MR image of the right kidney shows a subcapsular collection with a target appearance, a finding indicative of hemoglobin degradation in a subacute hematoma. (c) Gadolinium-enhanced, fat-suppressed T1-weighted MR image reveals that the source of the hemorrhage was a papillary renal cell carcinoma (arrow).

View larger version (131K): [in a new window]   Figure 17b.  (a) Target sign (registered trademark of Target, Inc.). (b) T1-weighted MR image of the right kidney shows a subcapsular collection with a target appearance, a finding indicative of hemoglobin degradation in a subacute hematoma. (c) Gadolinium-enhanced, fat-suppressed T1-weighted MR image reveals that the source of the hemorrhage was a papillary renal cell carcinoma (arrow).

View larger version (108K): [in a new window]   Figure 17c.  (a) Target sign (registered trademark of Target, Inc.). (b) T1-weighted MR image of the right kidney shows a subcapsular collection with a target appearance, a finding indicative of hemoglobin degradation in a subacute hematoma. (c) Gadolinium-enhanced, fat-suppressed T1-weighted MR image reveals that the source of the hemorrhage was a papillary renal cell carcinoma (arrow).

View larger version (47K): [in a new window]   Figure 18.  Kidney sweat. Longitudinal US image of the left kidney in a patient with acute renal failure reveals a sliver of fluid in a subcapsular location (arrow). This appearance has been called kidney sweat. Similar findings were seen on the right.

View larger version (122K): [in a new window]   Figure 19.  Kidney sweat. In another patient with acute renal failure, the T2-weighted MR image shows kidney sweat on the left (arrow). A balloon on a string appearance is seen in the right kidney, which had no excretory function because of severe parenchymal atrophy.

View larger version (136K): [in a new window]   Figure 20a.  Horseshoe kidney. (a) Horseshoe. (b) Enhanced CT image shows the functional isthmus of a horseshoe kidney anterior to the aorta, immediately beneath the inferior mesenteric artery (arrow).

View larger version (123K): [in a new window]   Figure 20b.  Horseshoe kidney. (a) Horseshoe. (b) Enhanced CT image shows the functional isthmus of a horseshoe kidney anterior to the aorta, immediately beneath the inferior mesenteric artery (arrow).

View larger version (142K): [in a new window]   Figure 21a.  Horseshoe kidney. (a) Midstream aortogram demonstrates multiple renal arteries supplying a horseshoe kidney (black arrows and arrowheads). Note the position of the inferior mesenteric artery (white arrow). (b) Late phase image from aortography demonstrates the horseshoe kidney configuration (arrow), with the superior aspect of the isthmus immediately below the origin of the inferior mesenteric artery.

View larger version (159K): [in a new window]   Figure 21b.  Horseshoe kidney. (a) Midstream aortogram demonstrates multiple renal arteries supplying a horseshoe kidney (black arrows and arrowheads). Note the position of the inferior mesenteric artery (white arrow). (b) Late phase image from aortography demonstrates the horseshoe kidney configuration (arrow), with the superior aspect of the isthmus immediately below the origin of the inferior mesenteric artery.

View larger version (113K): [in a new window]   Figure 22a.  (a) One kind of loop-to-loop. (b) Preliminary image from excretory urography demonstrates a looped configuration of the distal transverse colon and splenic flexure (arrows). (c) Tomogram from excretory urography demonstrates absence of the left kidney and deviation of the descending colon into the renal fossa.

View larger version (154K): [in a new window]   Figure 22b.  (a) One kind of loop-to-loop. (b) Preliminary image from excretory urography demonstrates a looped configuration of the distal transverse colon and splenic flexure (arrows). (c) Tomogram from excretory urography demonstrates absence of the left kidney and deviation of the descending colon into the renal fossa.

View larger version (175K): [in a new window]   Figure 22c.  (a) One kind of loop-to-loop. (b) Preliminary image from excretory urography demonstrates a looped configuration of the distal transverse colon and splenic flexure (arrows). (c) Tomogram from excretory urography demonstrates absence of the left kidney and deviation of the descending colon into the renal fossa.

View larger version (125K): [in a new window]   Figure 23a.  Lying down adrenal glands. US images of the right (a) and left (b) renal fossae demonstrate absence of the kidneys, and long, slender adrenal glands (arrows) in an infant with bilateral renal agenesis.

View larger version (96K): [in a new window]   Figure 23b.  Lying down adrenal glands. US images of the right (a) and left (b) renal fossae demonstrate absence of the kidneys, and long, slender adrenal glands (arrows) in an infant with bilateral renal agenesis.

View larger version (138K): [in a new window]   Figure 24a.  (a) Dromedary camel (registered trademark of R. J. Reynolds Tobacco Co.). (b) Dromedary hump. Tomogram from excretory urography demonstrates a prominent cortical hump in the interpolar region of the left kidney. (c) On a compression image obtained in a later phase of the sequence, the hump is subtended by a normal collecting system element, indicating that it represents normal functioning tissue.

View larger version (131K): [in a new window]   Figure 24b.  (a) Dromedary camel (registered trademark of R. J. Reynolds Tobacco Co.). (b) Dromedary hump. Tomogram from excretory urography demonstrates a prominent cortical hump in the interpolar region of the left kidney. (c) On a compression image obtained in a later phase of the sequence, the hump is subtended by a normal collecting system element, indicating that it represents normal functioning tissue.

View larger version (141K): [in a new window]   Figure 24c.  (a) Dromedary camel (registered trademark of R. J. Reynolds Tobacco Co.). (b) Dromedary hump. Tomogram from excretory urography demonstrates a prominent cortical hump in the interpolar region of the left kidney. (c) On a compression image obtained in a later phase of the sequence, the hump is subtended by a normal collecting system element, indicating that it represents normal functioning tissue.

View larger version (48K): [in a new window]   Figure 25.  Drawings illustrate a variety of pseudomasses that can be created by normal renal tissue: fetal lobation (A), dromedary hump (B), cortical column (arrow) (C), and prominent hilar lips (arrowheads) (D). Familiarity with the typical locations and appearances of pseudomasses aids in the correct diagnosis.

View larger version (182K): [in a new window]   Figure 26a.   Putty kidney. (a) Putty kidney. (b) Plain radiograph of the abdomen demonstrates extensive calcification in the left kidney, which was nonfunctional (the putty kidney), consistent with autonephrectomy from tuberculosis.

View larger version (168K): [in a new window]   Figure 26b.   Putty kidney. (a) Putty kidney. (b) Plain radiograph of the abdomen demonstrates extensive calcification in the left kidney, which was nonfunctional (the putty kidney), consistent with autonephrectomy from tuberculosis.

View larger version (143K): [in a new window]   Figure 27a.   Putty kidney. CT images through the upper (a) and lower (b) regions in another patient with autonephrectomy of a left-sided, putty kidney demonstrate the extensive parenchymal and collecting system calcification as a result of tuberculosis infection.

View larger version (139K): [in a new window]   Figure 27b.   Putty kidney. CT images through the upper (a) and lower (b) regions in another patient with autonephrectomy of a left-sided, putty kidney demonstrate the extensive parenchymal and collecting system calcification as a result of tuberculosis infection.

View larger version (117K): [in a new window]   Figure 28a.  (a) Ball-on-tee. (b) Lobster claws with lobster. (c) Drawing illustrates the different patterns of excavation that can be seen with papillary necrosis: normal (A), central excavation with ball-on-tee appearance (B), forniceal excavation (C), lobster claw appearance (D), signet ring appearance (E), and sloughed papilla with clubbed calix (F).

View larger version (148K): [in a new window]   Figure 28b.  (a) Ball-on-tee. (b) Lobster claws with lobster. (c) Drawing illustrates the different patterns of excavation that can be seen with papillary necrosis: normal (A), central excavation with ball-on-tee appearance (B), forniceal excavation (C), lobster claw appearance (D), signet ring appearance (E), and sloughed papilla with clubbed calix (F).

View larger version (49K): [in a new window]   Figure 28c.  (a) Ball-on-tee. (b) Lobster claws with lobster. (c) Drawing illustrates the different patterns of excavation that can be seen with papillary necrosis: normal (A), central excavation with ball-on-tee appearance (B), forniceal excavation (C), lobster claw appearance (D), signet ring appearance (E), and sloughed papilla with clubbed calix (F).

View larger version (115K): [in a new window]   Figure 29.  Papillary necrosis. On an excretory urogram, contrast material fills central excavations (arrows) in the papilla of the interpolar region, giving the ball-on-tee appearance. Note the abnormal calices in the upper and lower poles as well.

View larger version (123K): [in a new window]   Figure 30.  Papillary necrosis. Excavation extending from the caliceal fornices (arrows) produces the lobster claw deformity in another patient.

View larger version (115K): [in a new window]   Figure 31a.  Papillary necrosis. (a) Tomogram demonstrates triangular, peripherally calcified structures (arrows)—the sloughed papilla—in the region of the left ureter. (b) Retrograde ureteropyelogram demonstrates contrast material surrounding sloughed papilla retained in some of the calices, producing the signet ring appearance (arrows).

View larger version (107K): [in a new window]   Figure 31b.  Papillary necrosis. (a) Tomogram demonstrates triangular, peripherally calcified structures (arrows)—the sloughed papilla—in the region of the left ureter. (b) Retrograde ureteropyelogram demonstrates contrast material surrounding sloughed papilla retained in some of the calices, producing the signet ring appearance (arrows).

View larger version (91K): [in a new window]   Figure 32a.  Phantom calix. (a) On an excretory urogram, stricturing of the superior infundibulum caused by tuberculosis has obliterated the upper calix (arrow), producing a phantom calix. (b) On image of another patient, a mass in the upper pole of the right kidney has destroyed the caliceal elements normally seen in this region. In this case, the phantom calices are secondary to renal cell carcinoma.

View larger version (146K): [in a new window]   Figure 32b.  Phantom calix. (a) On an excretory urogram, stricturing of the superior infundibulum caused by tuberculosis has obliterated the upper calix (arrow), producing a phantom calix. (b) On image of another patient, a mass in the upper pole of the right kidney has destroyed the caliceal elements normally seen in this region. In this case, the phantom calices are secondary to renal cell carcinoma.

View larger version (88K): [in a new window]   Figure 33a.  Faceless kidney sign. (a, b) Kidney with (a) and without (b) a face. (c) Unenhanced CT image through the kidneys shows absence of the typical sinus signature in the left kidney. (d) Contrast-enhanced image, obtained at the same level as seen in c, shows normal parenchymal enhancement. (e) Delayed image obtained at the lower aspect of the left kidney shows the presence of two ureters (arrowheads). (f) Excretory urogram demonstrates duplication of the left collecting system, with the two separate collecting system elements and two ureters exiting the kidney. It is easy to see how the images in c and d were generated from a position between the collecting system elements.

View larger version (82K): [in a new window]   Figure 33b.  Faceless kidney sign. (a, b) Kidney with (a) and without (b) a face. (c) Unenhanced CT image through the kidneys shows absence of the typical sinus signature in the left kidney. (d) Contrast-enhanced image, obtained at the same level as seen in c, shows normal parenchymal enhancement. (e) Delayed image obtained at the lower aspect of the left kidney shows the presence of two ureters (arrowheads). (f) Excretory urogram demonstrates duplication of the left collecting system, with the two separate collecting system elements and two ureters exiting the kidney. It is easy to see how the images in c and d were generated from a position between the collecting system elements.

View larger version (146K): [in a new window]   Figure 33c.  Faceless kidney sign. (a, b) Kidney with (a) and without (b) a face. (c) Unenhanced CT image through the kidneys shows absence of the typical sinus signature in the left kidney. (d) Contrast-enhanced image, obtained at the same level as seen in c, shows normal parenchymal enhancement. (e) Delayed image obtained at the lower aspect of the left kidney shows the presence of two ureters (arrowheads). (f) Excretory urogram demonstrates duplication of the left collecting system, with the two separate collecting system elements and two ureters exiting the kidney. It is easy to see how the images in c and d were generated from a position between the collecting system elements.

View larger version (124K): [in a new window]   Figure 33d.  Faceless kidney sign. (a, b) Kidney with (a) and without (b) a face. (c) Unenhanced CT image through the kidneys shows absence of the typical sinus signature in the left kidney. (d) Contrast-enhanced image, obtained at the same level as seen in c, shows normal parenchymal enhancement. (e) Delayed image obtained at the lower aspect of the left kidney shows the presence of two ureters (arrowheads). (f) Excretory urogram demonstrates duplication of the left collecting system, with the two separate collecting system elements and two ureters exiting the kidney. It is easy to see how the images in c and d were generated from a position between the collecting system elements.

View larger version (128K): [in a new window]   Figure 33e.  Faceless kidney sign. (a, b) Kidney with (a) and without (b) a face. (c) Unenhanced CT image through the kidneys shows absence of the typical sinus signature in the left kidney. (d) Contrast-enhanced image, obtained at the same level as seen in c, shows normal parenchymal enhancement. (e) Delayed image obtained at the lower aspect of the left kidney shows the presence of two ureters (arrowheads). (f) Excretory urogram demonstrates duplication of the left collecting system, with the two separate collecting system elements and two ureters exiting the kidney. It is easy to see how the images in c and d were generated from a position between the collecting system elements.

View larger version (109K): [in a new window]   Figure 33f.  Faceless kidney sign. (a, b) Kidney with (a) and without (b) a face. (c) Unenhanced CT image through the kidneys shows absence of the typical sinus signature in the left kidney. (d) Contrast-enhanced image, obtained at the same level as seen in c, shows normal parenchymal enhancement. (e) Delayed image obtained at the lower aspect of the left kidney shows the presence of two ureters (arrowheads). (f) Excretory urogram demonstrates duplication of the left collecting system, with the two separate collecting system elements and two ureters exiting the kidney. It is easy to see how the images in c and d were generated from a position between the collecting system elements.

View larger version (135K): [in a new window]   Figure 34a.  Faceless kidney. (a) Unenhanced CT image shows absence of the central sinus signature in the left kidney. Note perinephric stranding and abnormalities in the hilar region. (b) Enhanced image obtained at the same level as a shows abnormal parenchymal enhancement, in this case from a diffusely infiltrating transitional cell carcinoma.

View larger version (144K): [in a new window]   Figure 34b.  Faceless kidney. (a) Unenhanced CT image shows absence of the central sinus signature in the left kidney. Note perinephric stranding and abnormalities in the hilar region. (b) Enhanced image obtained at the same level as a shows abnormal parenchymal enhancement, in this case from a diffusely infiltrating transitional cell carcinoma.

View larger version (139K): [in a new window]   Figure 35a.  Faceless kidney. (a) US image of the right kidney (same patient as in Fig 34) shows the normal sonographic signature of the renal sinus. (b) Sonographic sinus signature in the left kidney is grossly distorted due to infiltration by transitional cell carcinoma.

View larger version (140K): [in a new window]   Figure 35b.  Faceless kidney. (a) US image of the right kidney (same patient as in Fig 34) shows the normal sonographic signature of the renal sinus. (b) Sonographic sinus signature in the left kidney is grossly distorted due to infiltration by transitional cell carcinoma.

View larger version (84K): [in a new window]   Figure 36a.  (a) Drooping lily. (b) Excretory urogram of an infant with a urinary tract infection demonstrates downward and lateral displacement of the opacified lower pole moiety of a duplicated system (the drooping lily appearance) caused by the dilated, obstructed collecting system and ureter of the nonfunctional upper pole moiety.

View larger version (131K): [in a new window]   Figure 36b.  (a) Drooping lily. (b) Excretory urogram of an infant with a urinary tract infection demonstrates downward and lateral displacement of the opacified lower pole moiety of a duplicated system (the drooping lily appearance) caused by the dilated, obstructed collecting system and ureter of the nonfunctional upper pole moiety.

View larger version (56K): [in a new window]   Figure 37a.  Maiden waist deformity. (a) Radiograph of Barbie (registered trademark of Mattel) clearly depicts a narrow-waisted maiden. (b) Composite image of bilateral retrograde examinations performed in a patient with renal failure and minimal hydronephrosis shows narrowed areas in both ureters at the lumbosacral junction with medial deviation. This appearance has been described as the maiden waist deformity of the ureters.

View larger version (116K): [in a new window]   Figure 37b.  Maiden waist deformity. (a) Radiograph of Barbie (registered trademark of Mattel) clearly depicts a narrow-waisted maiden. (b) Composite image of bilateral retrograde examinations performed in a patient with renal failure and minimal hydronephrosis shows narrowed areas in both ureters at the lumbosacral junction with medial deviation. This appearance has been described as the maiden waist deformity of the ureters.

View larger version (152K): [in a new window]   Figure 38a.  Retroperitoneal fibrosis. (a) CT image of another patient demonstrates moderate hydronephrosis with delay in development of the tubular nephrogram on the right. (b) On CT scan obtained at a lower level, the right ureter can be seen entering a fibrotic plaque surrounding the aorta and inferior vena cava at the lumbosacral junction.