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CT Urography¹

¹ From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. Presented as an education exhibit at the 2003 RSNA scientific assembly. Received March 1, 2004; revision requested March 26; final revision received June 4; accepted June 7. All authors have no financial relationships to disclose. Address correspondence to A.K. (e-mail: kawashima.akira@mayo.edu).

View larger version (123K): [in a new window]   Figure 1.  Combined CT and EU CT urography technique used at the authors’ institution. Photograph shows a multi-detector row helical CT scanner and an overhead radiographic x-ray tube (arrowhead). The modified CT tabletop (curved white arrow) is made of carbon fiber material. A screen-film cassette (large black arrow) in a stationary slip-in grid (small black arrow) is inserted into the opening (straight white arrow) of the auxiliary CT tabletop. The auxiliary CT tabletop moves so that a patient can be accurately positioned underneath the overhead radiographic x-ray tube.

View larger version (147K): [in a new window]   Figure 2a.  Standard CT urography image sequence for the combined CT and EU CT urography technique used at the authors’ institution. (a) Abdominal radiograph shows a small opaque calculus projected over the right kidney (arrow). (b) Unenhanced CT scan shows normal renal parenchyma and the calculus in the interpolar portion of the right kidney. (c, d) Contrast-enhanced CT scans obtained during the homogeneous nephrographic (c) and pyelographic (d) phases show the normal nephrographic progression. On the pyelographic phase image (d), the calculus is obscured in the contrast material-filled calix. (e) Eight-minute excretory urogram obtained with application of external ureteral compression (arrows). (f) Ten-minute excretory urogram obtained after release of external ureteral compression.

View larger version (81K): [in a new window]   Figure 2b.  Standard CT urography image sequence for the combined CT and EU CT urography technique used at the authors’ institution. (a) Abdominal radiograph shows a small opaque calculus projected over the right kidney (arrow). (b) Unenhanced CT scan shows normal renal parenchyma and the calculus in the interpolar portion of the right kidney. (c, d) Contrast-enhanced CT scans obtained during the homogeneous nephrographic (c) and pyelographic (d) phases show the normal nephrographic progression. On the pyelographic phase image (d), the calculus is obscured in the contrast material-filled calix. (e) Eight-minute excretory urogram obtained with application of external ureteral compression (arrows). (f) Ten-minute excretory urogram obtained after release of external ureteral compression.

View larger version (96K): [in a new window]   Figure 2c.  Standard CT urography image sequence for the combined CT and EU CT urography technique used at the authors’ institution. (a) Abdominal radiograph shows a small opaque calculus projected over the right kidney (arrow). (b) Unenhanced CT scan shows normal renal parenchyma and the calculus in the interpolar portion of the right kidney. (c, d) Contrast-enhanced CT scans obtained during the homogeneous nephrographic (c) and pyelographic (d) phases show the normal nephrographic progression. On the pyelographic phase image (d), the calculus is obscured in the contrast material-filled calix. (e) Eight-minute excretory urogram obtained with application of external ureteral compression (arrows). (f) Ten-minute excretory urogram obtained after release of external ureteral compression.

View larger version (61K): [in a new window]   Figure 2d.  Standard CT urography image sequence for the combined CT and EU CT urography technique used at the authors’ institution. (a) Abdominal radiograph shows a small opaque calculus projected over the right kidney (arrow). (b) Unenhanced CT scan shows normal renal parenchyma and the calculus in the interpolar portion of the right kidney. (c, d) Contrast-enhanced CT scans obtained during the homogeneous nephrographic (c) and pyelographic (d) phases show the normal nephrographic progression. On the pyelographic phase image (d), the calculus is obscured in the contrast material-filled calix. (e) Eight-minute excretory urogram obtained with application of external ureteral compression (arrows). (f) Ten-minute excretory urogram obtained after release of external ureteral compression.

View larger version (116K): [in a new window]   Figure 2e.  Standard CT urography image sequence for the combined CT and EU CT urography technique used at the authors’ institution. (a) Abdominal radiograph shows a small opaque calculus projected over the right kidney (arrow). (b) Unenhanced CT scan shows normal renal parenchyma and the calculus in the interpolar portion of the right kidney. (c, d) Contrast-enhanced CT scans obtained during the homogeneous nephrographic (c) and pyelographic (d) phases show the normal nephrographic progression. On the pyelographic phase image (d), the calculus is obscured in the contrast material-filled calix. (e) Eight-minute excretory urogram obtained with application of external ureteral compression (arrows). (f) Ten-minute excretory urogram obtained after release of external ureteral compression.

View larger version (115K): [in a new window]   Figure 2f.  Standard CT urography image sequence for the combined CT and EU CT urography technique used at the authors’ institution. (a) Abdominal radiograph shows a small opaque calculus projected over the right kidney (arrow). (b) Unenhanced CT scan shows normal renal parenchyma and the calculus in the interpolar portion of the right kidney. (c, d) Contrast-enhanced CT scans obtained during the homogeneous nephrographic (c) and pyelographic (d) phases show the normal nephrographic progression. On the pyelographic phase image (d), the calculus is obscured in the contrast material-filled calix. (e) Eight-minute excretory urogram obtained with application of external ureteral compression (arrows). (f) Ten-minute excretory urogram obtained after release of external ureteral compression.

View larger version (103K): [in a new window]   Figure 3a.  Different types of projection radiographic images used in urography. (a) Conventional 10-minute excretory urogram. (b) Corresponding CT SPR image obtained at 80 kVp and 300 mA shows a dark band along the margin of the iodinated contrast material (arrows). (c) Modified CT SPR image, obtained after reprocessing of the original CT SPR image data in b with clinically optimized algorithms, shows substantial minimization of the artifacts and appears similar to the conventional urogram (a).

View larger version (108K): [in a new window]   Figure 3b.  Different types of projection radiographic images used in urography. (a) Conventional 10-minute excretory urogram. (b) Corresponding CT SPR image obtained at 80 kVp and 300 mA shows a dark band along the margin of the iodinated contrast material (arrows). (c) Modified CT SPR image, obtained after reprocessing of the original CT SPR image data in b with clinically optimized algorithms, shows substantial minimization of the artifacts and appears similar to the conventional urogram (a).

View larger version (97K): [in a new window]   Figure 3c.  Different types of projection radiographic images used in urography. (a) Conventional 10-minute excretory urogram. (b) Corresponding CT SPR image obtained at 80 kVp and 300 mA shows a dark band along the margin of the iodinated contrast material (arrows). (c) Modified CT SPR image, obtained after reprocessing of the original CT SPR image data in b with clinically optimized algorithms, shows substantial minimization of the artifacts and appears similar to the conventional urogram (a).

View larger version (158K): [in a new window]   Figure 4a.  Obstructing transitional cell carcinoma of the ureter. Different types of reformatted images generated from CT images are compared with a conventional EU image. (a) Twenty-minute excretory urogram shows left pyelocaliectasis and ureterectasis to the level of the iliac crest, where the dilated ureter abruptly terminates (straight arrow). There is extravasation of urinary contrast material around the left renal pelvis and proximal ureter (curved arrows) secondary to forniceal rupture. (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the left ureter with associated periureteral soft-tissue thickening (arrow). No lymphadenopathy was identified. (c) Curved reformatted image shows the soft-tissue attenuation mass with resulting ureteral obstruction (arrow). The left ureter distal to the lesion is not dilated. (d-f) Three-dimensional maximum intensity projection (MIP) (d), average intensity projection (e), and perspective volume rendered (f) reformatted images show findings similar to those on the conventional urogram (a). The diagnosis was invasive grade 3 (of three grades) urothelial carcinoma with invasion into the periureteral fat plane.

View larger version (183K): [in a new window]   Figure 4b.  Obstructing transitional cell carcinoma of the ureter. Different types of reformatted images generated from CT images are compared with a conventional EU image. (a) Twenty-minute excretory urogram shows left pyelocaliectasis and ureterectasis to the level of the iliac crest, where the dilated ureter abruptly terminates (straight arrow). There is extravasation of urinary contrast material around the left renal pelvis and proximal ureter (curved arrows) secondary to forniceal rupture. (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the left ureter with associated periureteral soft-tissue thickening (arrow). No lymphadenopathy was identified. (c) Curved reformatted image shows the soft-tissue attenuation mass with resulting ureteral obstruction (arrow). The left ureter distal to the lesion is not dilated. (d-f) Three-dimensional maximum intensity projection (MIP) (d), average intensity projection (e), and perspective volume rendered (f) reformatted images show findings similar to those on the conventional urogram (a). The diagnosis was invasive grade 3 (of three grades) urothelial carcinoma with invasion into the periureteral fat plane.

View larger version (156K): [in a new window]   Figure 4c.  Obstructing transitional cell carcinoma of the ureter. Different types of reformatted images generated from CT images are compared with a conventional EU image. (a) Twenty-minute excretory urogram shows left pyelocaliectasis and ureterectasis to the level of the iliac crest, where the dilated ureter abruptly terminates (straight arrow). There is extravasation of urinary contrast material around the left renal pelvis and proximal ureter (curved arrows) secondary to forniceal rupture. (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the left ureter with associated periureteral soft-tissue thickening (arrow). No lymphadenopathy was identified. (c) Curved reformatted image shows the soft-tissue attenuation mass with resulting ureteral obstruction (arrow). The left ureter distal to the lesion is not dilated. (d-f) Three-dimensional maximum intensity projection (MIP) (d), average intensity projection (e), and perspective volume rendered (f) reformatted images show findings similar to those on the conventional urogram (a). The diagnosis was invasive grade 3 (of three grades) urothelial carcinoma with invasion into the periureteral fat plane.

View larger version (147K): [in a new window]   Figure 4d.  Obstructing transitional cell carcinoma of the ureter. Different types of reformatted images generated from CT images are compared with a conventional EU image. (a) Twenty-minute excretory urogram shows left pyelocaliectasis and ureterectasis to the level of the iliac crest, where the dilated ureter abruptly terminates (straight arrow). There is extravasation of urinary contrast material around the left renal pelvis and proximal ureter (curved arrows) secondary to forniceal rupture. (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the left ureter with associated periureteral soft-tissue thickening (arrow). No lymphadenopathy was identified. (c) Curved reformatted image shows the soft-tissue attenuation mass with resulting ureteral obstruction (arrow). The left ureter distal to the lesion is not dilated. (d-f) Three-dimensional maximum intensity projection (MIP) (d), average intensity projection (e), and perspective volume rendered (f) reformatted images show findings similar to those on the conventional urogram (a). The diagnosis was invasive grade 3 (of three grades) urothelial carcinoma with invasion into the periureteral fat plane.

View larger version (153K): [in a new window]   Figure 4e.  Obstructing transitional cell carcinoma of the ureter. Different types of reformatted images generated from CT images are compared with a conventional EU image. (a) Twenty-minute excretory urogram shows left pyelocaliectasis and ureterectasis to the level of the iliac crest, where the dilated ureter abruptly terminates (straight arrow). There is extravasation of urinary contrast material around the left renal pelvis and proximal ureter (curved arrows) secondary to forniceal rupture. (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the left ureter with associated periureteral soft-tissue thickening (arrow). No lymphadenopathy was identified. (c) Curved reformatted image shows the soft-tissue attenuation mass with resulting ureteral obstruction (arrow). The left ureter distal to the lesion is not dilated. (d-f) Three-dimensional maximum intensity projection (MIP) (d), average intensity projection (e), and perspective volume rendered (f) reformatted images show findings similar to those on the conventional urogram (a). The diagnosis was invasive grade 3 (of three grades) urothelial carcinoma with invasion into the periureteral fat plane.

View larger version (144K): [in a new window]   Figure 4f.  Obstructing transitional cell carcinoma of the ureter. Different types of reformatted images generated from CT images are compared with a conventional EU image. (a) Twenty-minute excretory urogram shows left pyelocaliectasis and ureterectasis to the level of the iliac crest, where the dilated ureter abruptly terminates (straight arrow). There is extravasation of urinary contrast material around the left renal pelvis and proximal ureter (curved arrows) secondary to forniceal rupture. (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the left ureter with associated periureteral soft-tissue thickening (arrow). No lymphadenopathy was identified. (c) Curved reformatted image shows the soft-tissue attenuation mass with resulting ureteral obstruction (arrow). The left ureter distal to the lesion is not dilated. (d-f) Three-dimensional maximum intensity projection (MIP) (d), average intensity projection (e), and perspective volume rendered (f) reformatted images show findings similar to those on the conventional urogram (a). The diagnosis was invasive grade 3 (of three grades) urothelial carcinoma with invasion into the periureteral fat plane.

View larger version (101K): [in a new window]   Figure 5a.  Superficially invasive papillary urothelial carcinoma of the intrarenal collecting system, grade 2 (of three grades). (a) Eight-minute excretory urogram shows amputation of the upper left renal infundibulum (straight arrow) with distortion of upper pole calices (curved arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the central portion of the upper left kidney (straight arrow) with associated renal parenchymal loss and caliceal distortion (curved arrow). Neither lymphadenopathy nor extrarenal tumor extension was identified. (c) Coronal reformatted image generated from thin-section axial CT scans obtained during the excretory phase (b) shows the relationship of the amputated infundibulum to the mass. (d) Three-dimensional MIP image shows a left pyelocaliceal system that appears similar to that seen on the conventional urogram (a) with an amputated infundibulum (arrow).

View larger version (154K): [in a new window]   Figure 5b.  Superficially invasive papillary urothelial carcinoma of the intrarenal collecting system, grade 2 (of three grades). (a) Eight-minute excretory urogram shows amputation of the upper left renal infundibulum (straight arrow) with distortion of upper pole calices (curved arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the central portion of the upper left kidney (straight arrow) with associated renal parenchymal loss and caliceal distortion (curved arrow). Neither lymphadenopathy nor extrarenal tumor extension was identified. (c) Coronal reformatted image generated from thin-section axial CT scans obtained during the excretory phase (b) shows the relationship of the amputated infundibulum to the mass. (d) Three-dimensional MIP image shows a left pyelocaliceal system that appears similar to that seen on the conventional urogram (a) with an amputated infundibulum (arrow).

View larger version (111K): [in a new window]   Figure 5c.  Superficially invasive papillary urothelial carcinoma of the intrarenal collecting system, grade 2 (of three grades). (a) Eight-minute excretory urogram shows amputation of the upper left renal infundibulum (straight arrow) with distortion of upper pole calices (curved arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the central portion of the upper left kidney (straight arrow) with associated renal parenchymal loss and caliceal distortion (curved arrow). Neither lymphadenopathy nor extrarenal tumor extension was identified. (c) Coronal reformatted image generated from thin-section axial CT scans obtained during the excretory phase (b) shows the relationship of the amputated infundibulum to the mass. (d) Three-dimensional MIP image shows a left pyelocaliceal system that appears similar to that seen on the conventional urogram (a) with an amputated infundibulum (arrow).

View larger version (97K): [in a new window]   Figure 5d.  Superficially invasive papillary urothelial carcinoma of the intrarenal collecting system, grade 2 (of three grades). (a) Eight-minute excretory urogram shows amputation of the upper left renal infundibulum (straight arrow) with distortion of upper pole calices (curved arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows a soft-tissue attenuation mass in the central portion of the upper left kidney (straight arrow) with associated renal parenchymal loss and caliceal distortion (curved arrow). Neither lymphadenopathy nor extrarenal tumor extension was identified. (c) Coronal reformatted image generated from thin-section axial CT scans obtained during the excretory phase (b) shows the relationship of the amputated infundibulum to the mass. (d) Three-dimensional MIP image shows a left pyelocaliceal system that appears similar to that seen on the conventional urogram (a) with an amputated infundibulum (arrow).

View larger version (125K): [in a new window]   Figure 6a.  Caliceal urothelial carcinoma in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (Lynch syndrome) whose history included bladder carcinoma, endometrioid ovarian carcinoma, endometrial carcinoma, and colonic polyps. (a) Eight-minute excretory urogram shows a filling defect in the upper renal calix (arrow). Bowel gas projected over the right kidney and renal collecting system obscures detail. (b, c) Oblique axial (b) and coronal (c) reformatted images generated from pyelographic phase CT scans obtained with 1.25-mm section thickness show a polypoid tumor (arrow), which is confined to the intrarenal collecting system with no obliteration of the peripelvic fat plane. No lymphadenopathy is identified. (d) Three-dimensional MIP image shows distortion of the upper renal calices (arrow). Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was treated with endourologic laser ablation.

View larger version (117K): [in a new window]   Figure 6b.  Caliceal urothelial carcinoma in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (Lynch syndrome) whose history included bladder carcinoma, endometrioid ovarian carcinoma, endometrial carcinoma, and colonic polyps. (a) Eight-minute excretory urogram shows a filling defect in the upper renal calix (arrow). Bowel gas projected over the right kidney and renal collecting system obscures detail. (b, c) Oblique axial (b) and coronal (c) reformatted images generated from pyelographic phase CT scans obtained with 1.25-mm section thickness show a polypoid tumor (arrow), which is confined to the intrarenal collecting system with no obliteration of the peripelvic fat plane. No lymphadenopathy is identified. (d) Three-dimensional MIP image shows distortion of the upper renal calices (arrow). Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was treated with endourologic laser ablation.

View larger version (98K): [in a new window]   Figure 6c.  Caliceal urothelial carcinoma in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (Lynch syndrome) whose history included bladder carcinoma, endometrioid ovarian carcinoma, endometrial carcinoma, and colonic polyps. (a) Eight-minute excretory urogram shows a filling defect in the upper renal calix (arrow). Bowel gas projected over the right kidney and renal collecting system obscures detail. (b, c) Oblique axial (b) and coronal (c) reformatted images generated from pyelographic phase CT scans obtained with 1.25-mm section thickness show a polypoid tumor (arrow), which is confined to the intrarenal collecting system with no obliteration of the peripelvic fat plane. No lymphadenopathy is identified. (d) Three-dimensional MIP image shows distortion of the upper renal calices (arrow). Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was treated with endourologic laser ablation.

View larger version (82K): [in a new window]   Figure 6d.  Caliceal urothelial carcinoma in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (Lynch syndrome) whose history included bladder carcinoma, endometrioid ovarian carcinoma, endometrial carcinoma, and colonic polyps. (a) Eight-minute excretory urogram shows a filling defect in the upper renal calix (arrow). Bowel gas projected over the right kidney and renal collecting system obscures detail. (b, c) Oblique axial (b) and coronal (c) reformatted images generated from pyelographic phase CT scans obtained with 1.25-mm section thickness show a polypoid tumor (arrow), which is confined to the intrarenal collecting system with no obliteration of the peripelvic fat plane. No lymphadenopathy is identified. (d) Three-dimensional MIP image shows distortion of the upper renal calices (arrow). Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was treated with endourologic laser ablation.

View larger version (160K): [in a new window]   Figure 7a.  Urothelial carcinoma of the ipsilateral ureter in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (same patient as in Fig 6). (a) Ten-minute excretory urogram shows a round filling defect in the distal right ureter (arrow). (b, c) Oblique coronal (b) and axial (c) reformatted images show the filling defect in the distal right ureter (arrow). Neither obliteration of the periureteral fat plane nor lymphadenopathy is identified. Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was also treated with endourologic laser ablation.

View larger version (137K): [in a new window]   Figure 7b.  Urothelial carcinoma of the ipsilateral ureter in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (same patient as in Fig 6). (a) Ten-minute excretory urogram shows a round filling defect in the distal right ureter (arrow). (b, c) Oblique coronal (b) and axial (c) reformatted images show the filling defect in the distal right ureter (arrow). Neither obliteration of the periureteral fat plane nor lymphadenopathy is identified. Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was also treated with endourologic laser ablation.

View larger version (93K): [in a new window]   Figure 7c.  Urothelial carcinoma of the ipsilateral ureter in a 60-year-old woman with hereditary nonpolyposis colorectal cancer syndrome (same patient as in Fig 6). (a) Ten-minute excretory urogram shows a round filling defect in the distal right ureter (arrow). (b, c) Oblique coronal (b) and axial (c) reformatted images show the filling defect in the distal right ureter (arrow). Neither obliteration of the periureteral fat plane nor lymphadenopathy is identified. Ureteroscopic biopsy revealed grade 2 (of three grades) urothelial carcinoma, which was also treated with endourologic laser ablation.

View larger version (113K): [in a new window]   Figure 8a.  Fibroepithelial polyps. (a) Ten-minute excretory urogram shows complex filling defects in the left ureter (arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness at the lumbosacral junction shows the small soft-tissue filling defects in the left ureter (thick straight arrow). Curved arrow = normal right ureter, thin straight arrows = calcification of the iliac arteries. (c) Curved reformatted image shows the multiple complex filling defects in the left ureter from the level of the lower renal pole to the level of the left iliac artery (arrow), which demonstrates calcification. Ureteroscopy demonstrated more than 15 polypoid lesions from the ureteropelvic junction down to the level of the iliac vessels, and biopsy revealed benign fibroepithelial polyps.

View larger version (43K): [in a new window]   Figure 8b.  Fibroepithelial polyps. (a) Ten-minute excretory urogram shows complex filling defects in the left ureter (arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness at the lumbosacral junction shows the small soft-tissue filling defects in the left ureter (thick straight arrow). Curved arrow = normal right ureter, thin straight arrows = calcification of the iliac arteries. (c) Curved reformatted image shows the multiple complex filling defects in the left ureter from the level of the lower renal pole to the level of the left iliac artery (arrow), which demonstrates calcification. Ureteroscopy demonstrated more than 15 polypoid lesions from the ureteropelvic junction down to the level of the iliac vessels, and biopsy revealed benign fibroepithelial polyps.

View larger version (77K): [in a new window]   Figure 8c.  Fibroepithelial polyps. (a) Ten-minute excretory urogram shows complex filling defects in the left ureter (arrow). (b) Excretory phase CT scan obtained with 1.25-mm section thickness at the lumbosacral junction shows the small soft-tissue filling defects in the left ureter (thick straight arrow). Curved arrow = normal right ureter, thin straight arrows = calcification of the iliac arteries. (c) Curved reformatted image shows the multiple complex filling defects in the left ureter from the level of the lower renal pole to the level of the left iliac artery (arrow), which demonstrates calcification. Ureteroscopy demonstrated more than 15 polypoid lesions from the ureteropelvic junction down to the level of the iliac vessels, and biopsy revealed benign fibroepithelial polyps.

View larger version (98K): [in a new window]   Figure 9a.  Papillary necrosis. (a) Eight-minute excretory urogram shows multiple small collections of contrast material in the papillary regions adjacent to calices (arrowheads), an appearance characteristic of papillary necrosis. (b) Excretory phase CT scan obtained with 1.25-mm section thickness through the upper kidneys shows the small contrast material-filled papillary cavities adjacent to calices bilaterally (arrowheads). (c) MIP image shows the small paracaliceal contrast material collections in the papillary regions (arrowheads), an appearance similar to that on the conventional urogram (a).

View larger version (71K): [in a new window]   Figure 9b.  Papillary necrosis. (a) Eight-minute excretory urogram shows multiple small collections of contrast material in the papillary regions adjacent to calices (arrowheads), an appearance characteristic of papillary necrosis. (b) Excretory phase CT scan obtained with 1.25-mm section thickness through the upper kidneys shows the small contrast material-filled papillary cavities adjacent to calices bilaterally (arrowheads). (c) MIP image shows the small paracaliceal contrast material collections in the papillary regions (arrowheads), an appearance similar to that on the conventional urogram (a).

View larger version (58K): [in a new window]   Figure 9c.  Papillary necrosis. (a) Eight-minute excretory urogram shows multiple small collections of contrast material in the papillary regions adjacent to calices (arrowheads), an appearance characteristic of papillary necrosis. (b) Excretory phase CT scan obtained with 1.25-mm section thickness through the upper kidneys shows the small contrast material-filled papillary cavities adjacent to calices bilaterally (arrowheads). (c) MIP image shows the small paracaliceal contrast material collections in the papillary regions (arrowheads), an appearance similar to that on the conventional urogram (a).

View larger version (141K): [in a new window]   Figure 10a.  Medullary sponge kidney. (a, b) Eight- minute excretory urogram (a) and reprocessed CT SPR image (b) show parallel striations of contrast material that extend peripherally from the surface of an upper right renal pole papilla (arrow), an appearance characteristic of medullary sponge kidney. The appearance of the streaks on the CT SPR image (b) is similar to that on the conventional urogram (a). (c) Excretory phase CT scan obtained with 1.25-mm section thickness shows multiple tiny dots of contrast material in the papillary region (arrow).

View larger version (131K): [in a new window]   Figure 10b.  Medullary sponge kidney. (a, b) Eight- minute excretory urogram (a) and reprocessed CT SPR image (b) show parallel striations of contrast material that extend peripherally from the surface of an upper right renal pole papilla (arrow), an appearance characteristic of medullary sponge kidney. The appearance of the streaks on the CT SPR image (b) is similar to that on the conventional urogram (a). (c) Excretory phase CT scan obtained with 1.25-mm section thickness shows multiple tiny dots of contrast material in the papillary region (arrow).

View larger version (94K): [in a new window]   Figure 10c.  Medullary sponge kidney. (a, b) Eight- minute excretory urogram (a) and reprocessed CT SPR image (b) show parallel striations of contrast material that extend peripherally from the surface of an upper right renal pole papilla (arrow), an appearance characteristic of medullary sponge kidney. The appearance of the streaks on the CT SPR image (b) is similar to that on the conventional urogram (a). (c) Excretory phase CT scan obtained with 1.25-mm section thickness shows multiple tiny dots of contrast material in the papillary region (arrow).

View larger version (75K): [in a new window]   Figure 11a.  Ureteritis cystica of the left ureter in a 60-year-old woman with a history of left renal stone. (a) Eight-minute excretory urogram shows multiple tiny, smooth, uniform filling defects in the left ureter (arrowheads). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows two tiny areas of urothelial elevation in the middle of the left ureter (arrows). (c) Oblique coronal reformatted image shows the many tiny filling defects in the left ureter (arrowheads). The small urothelial filling defects were obscured on thick-slab MIP images (not shown).

View larger version (61K): [in a new window]   Figure 11b.  Ureteritis cystica of the left ureter in a 60-year-old woman with a history of left renal stone. (a) Eight-minute excretory urogram shows multiple tiny, smooth, uniform filling defects in the left ureter (arrowheads). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows two tiny areas of urothelial elevation in the middle of the left ureter (arrows). (c) Oblique coronal reformatted image shows the many tiny filling defects in the left ureter (arrowheads). The small urothelial filling defects were obscured on thick-slab MIP images (not shown).

View larger version (90K): [in a new window]   Figure 11c.  Ureteritis cystica of the left ureter in a 60-year-old woman with a history of left renal stone. (a) Eight-minute excretory urogram shows multiple tiny, smooth, uniform filling defects in the left ureter (arrowheads). (b) Excretory phase CT scan obtained with 1.25-mm section thickness shows two tiny areas of urothelial elevation in the middle of the left ureter (arrows). (c) Oblique coronal reformatted image shows the many tiny filling defects in the left ureter (arrowheads). The small urothelial filling defects were obscured on thick-slab MIP images (not shown).