title: Pearls and pitfalls in the diagnosis of ureterolithiasis with unenhanced helical CT.
abstract: Several signs to assist interpretation of unenhanced helical computed tomographic (CT) scans obtained for suspected ureterolithiasis have been described. Because signs such as perinephric stranding are not always readily apparent, a methodical approach to interpretation of CT studies is important in determining the presence or absence of ureterolithiasis. Evaluation of the poles of the kidneys is helpful in detecting subtle stranding of the perinephric fat. Inspection of the intrarenal collecting system within the poles of the kidneys is helpful in identifying subtle collecting system dilatation and can help prevent mistaking an extrarenal pelvis for hydronephrosis. Careful inspection of the ureter throughout its course is the most reliable method of distinguishing between ureteral stones and phleboliths. However, when the ureter cannot be followed antegrade, the pelvic portion can often be identified in a retrograde fashion. When secondary signs of obstruction are present but no stone is present, differential diagnostic considerations include a recently passed stone, pyelonephritis, urinary tract obstruction unrelated to stone disease, and protease inhibitor deposition disease.
authors.affiliation: Department of Diagnostic Radiology, Wilford Hall Medical Center, Lackland Air Force Base, TX 78236-5302, USA. ncdalrymple@earthlink.net
authors.forename: N C
authors.initials: NC
authors.lastname: Dalrymple
authors.forename: B
authors.initials: B
authors.lastname: Casford
authors.forename: D P
authors.initials: DP
authors.lastname: Raiken
authors.forename: K D
authors.initials: KD
authors.lastname: Elsass
authors.forename: R A
authors.initials: RA
authors.lastname: Pagan
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D002137:Calculi / Q000000981:diagnostic imaging; D003460:Crystallization; D003937:Diagnosis, Differential; D004108:Dilatation, Pathologic / Q000000981:diagnostic imaging; D017320:HIV Protease Inhibitors / Q000378:metabolism; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007668:Kidney / Q000000981:diagnostic imaging; D007674:Kidney Diseases / Q000000981:diagnostic imaging; D007682:Kidney Pelvis / Q000002:abnormalities / Q000000981:diagnostic imaging; D007685:Kidney Tubules, Collecting / Q000000981:diagnostic imaging; D011704:Pyelonephritis / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014514:Ureteral Calculi / Q000000981:diagnostic imaging*; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging; D014652:Vascular Diseases / Q000000981:diagnostic imaging
chemical_list: D017320:HIV Protease Inhibitors