Does the Hounsfield unit value determined by computed tomography predict the outcome of percutaneous nephrolithotomy?
OBJECTIVE
We aimed to evaluate whether the Hounsfield unit (HU) value predicts outcome in percutaneous nephrolithotomy (PCNL).


METHODS
One hundred and seventy-nine patients who had undergone PCNL in our clinics in the last 4 years were included. Demographic and clinical data of the patients and complications, if any, were recorded. The mean age of the patients was 45.3 ± 14.3 years (range 5-82 y), and 111 of them were males (62%). The mean stone size and HU values were found to be 693.1 ± 628.0 (95-4200) mm(2) and 706.3 ± 245.0 (214-1325), respectively.


RESULTS
In logistic regression analysis, the size of the stone, the opacity of the stone, and the HU values were found to be independent predictors of the failure of the procedure (P<0.05). A cutoff value of 677.5 was used for the HU in the receiver operating characteristics analysis. Having a HU value under the cutoff value increased the likelihood of procedure failure by 2.65 times, whereas stones residing in the staghorn localization increased failure by 5.68. It was also observed that if the stone's size was 485 mm(2) or more, the chance of failure increased by 1.9, whereas when the stone was nonopaque, failure increased by 6.04 times (P<0.05). There was a positive correlation between hematocrit decrease and a decrease in HU values (P<0.05), but no correlation was observed between the HU values and duration of surgery or fluoroscopy (P>0.05).


CONCLUSIONS
In addition to the size and location of the stones, the HU value determined in the unenhanced CT scan may be one of the parameters affecting PCNL outcomes. PCNL is a more efficient method in stones with higher HU values. Therefore, the HU values may be a useful tool for the selection of the treatment modality in patients with renal stones.
Department of Urology, Abant Izzet Baysal University Faculty of Medicine, Bolu, Turkey. gucukadnan@hotmail.com
Adnan
A
Gücük
Uğur
U
Uyetürk
Ufuk
U
Oztürk
Eray
E
Kemahli
Mevlüt
M
Yildiz
Ahmet
A
Metin
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000601:surgery; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D011379:Prognosis; D012372:ROC Curve; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult