Hocaoglu E et al, 2015: Is quantitative diffusion-weighted MRI a valuable technique for the detection of changes in kidneys after extracorporeal shock wave lithotripsy?
Hocaoglu E, Inci E, Aydin S, Cesme DH, Kalfazade N.
Department of Radiology, Bakirkoy Dr. Sadi Konuk Research and Training Hospital, Istanbul, Turkey.
Department of Radiology, Haydarpasa Numune Research and Training Hospital, Istanbul, Turkey.
Department of Urology, Bakirkoy Dr. Sadi Konuk Research and Training Hospital, Istanbul, Turkey.
OBJECTIVE: The aim of this study was to evaluate the capability and the reliability of diffusion-weighted imaging (DWI) in the changes of kidneys occurring after extracorporeal shock wave lithotripsy (ESWL) treatment for renal stones.
MATERIALS AND METHODS: A total of 32 patients who underwent ESWL treatment for renal stone disease between June and December 2011 were enrolled in this prospective study. Color Doppler ultrasonography (CDUS) and DWI were performed before and within 24 hours after ESWL. DWI was obtained with b factors of 0, 500 and 1000 s/ mm2 at 1.5 T MRI. Each of Resistive index (RI) and ADC values were calculated from the three regions of renal upper, middle and lower zones for both of the affected and contralateral kidneys. Paired sample t test was used for statistical analyses.
RESULTS: After ESWL, the treated kidneys had statistically significant lower ADC values in all different regions compared with previous renal images. The best discriminative parameter was signal intensity with a b value of 1000 s/mm2. The changes of DWI after ESWL were noteworthy in the middle of the treated kidney (p < 0.01). There were no significant difference between RI values in all regions of treated and contralateral kidneys before and after treatment with ESWL (p>0.05).
CONCLUSION: DWI is a valuable technique enables the detection of changes in DWI after ESWL treatment that may provide useful information in prediction of renal damage by shock waves, even CDUS is normal.
Int Braz J Urol. 2015 Jan-Feb;41(1):139-46. doi: 10.1590/S1677-5538.IBJU.2015.01.19. FREE ARTICLE
More than 30 years of experience with SWL has taught us that transient morphological tissue changes are common after this treatment. In this study the authors have used MRI (DWI) before and after three sessions of piezoelectric lithotripsy. They were able to demonstrate significantly increased ACD-values (apparent diffusion coefficient) 24 hours after the last lithotripsy session. It is of note that in these patients no abnormalities were detected in terms of RI (resistive index).
The authors conclude that this technique enables detection of kidney changes that might be useful for prediction of renal damage. The real clinical value of DWI-measurements and how this technique can be used for prediction and prevention of injuries is not mentioned. Neither is there any information on how long these abnormal findings persist. From a clinical point of view: is it really necessary to look for and discover minor tissue lesions that probably are transient?