Contrast enhanced spiral computerized tomography in patients with chronic obstructive uropathy and normal serum creatinine: a single session for anatomical and functional assessment.
OBJECTIVE
We evaluated contrast enhanced spiral computerized tomography (CT) as a single session for the anatomical and functional assessment of patients with chronic obstructive uropathy and normal serum creatinine.


METHODS
The study included 65 patients with unilateral or bilateral chronic renal obstruction and normal serum creatinine. Five patients had bilateral obstruction and the remaining 60 had unilateral obstruction and a normal contralateral kidney. Therefore, the total number of renal units was 130, that is 70 obstructed and 60 normal. All patients underwent contrast enhanced spiral CT together with excretory urography (IVP) and Tc-mercaptoacetyltriglycine renal scan. CT was used to identify the cause of obstruction and selectively determine the glomerular filtration rate (GFR) of the 2 kidneys. The diagnostic accuracy of CT for identifying the cause of hydronephrosis was compared with that of IVP. Moreover, a correlation was made between CT GFR and isotope GFR.


RESULTS
Obstruction was caused by ureteropelvic junction narrowing in 25 cases, ureteral stones in 21, ureteral stricture in 20 and extrinsic ureteral obstruction in 4. Contrast enhanced spiral CT identified the cause of hydronephrosis in all obstructed kidneys (100% sensitivity), while IVP identified the cause in 52 (74% sensitivity), which was a significant difference (p <0.05). CT and IVP excluded obstruction in all normal kidneys (100% specificity). A comparison between the isotope GFR of obstructed kidneys with the corresponding CT GFR showed a perfect correlation (r = 0.78, p <0.0001). Moreover, a similar comparison between isotope GFR and CT GFR of normal kidneys showed an excellent correlation (r = 0.73, p <0.0001). In obstructed and normal kidneys mean isotope clearance was not significantly different from that of mean CT clearance.


CONCLUSIONS
Contrast enhanced spiral CT is more sensitive than IVP for identifying the cause of chronic obstructive uropathy. Moreover, it is as accurate as radioisotope renal scan for calculating the total and separate kidney function. We recommend spiral CT with contrast medium as a single radiological diagnostic modality for the assessment of patients with chronic renal obstruction and normal serum creatinine.
Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
Mohamed E Abo
ME
El-Ghar
Ahmed A
AA
Shokeir
Tarek A
TA
El-Diasty
Hoda F
HF
Refaie
Hossam M
HM
Gad
Ahmed B Shehab
AB
El-Dein
D000293:Adolescent; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D003287:Contrast Media; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006869:Hydronephrosis / Q000097:blood / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D007479:Iopamidol; D007668:Kidney / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography; D012680:Sensitivity and Specificity; D017263:Technetium Tc 99m Mertiatide; D036542:Tomography, Spiral Computed; D014513:Ureter / Q000000981:diagnostic imaging; D014514:Ureteral Calculi / Q000000981:diagnostic imaging; D014517:Ureteral Obstruction / Q000097:blood / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology
D003287:Contrast Media; D017263:Technetium Tc 99m Mertiatide; D003404:Creatinine; D007479:Iopamidol