Liu R et al, 2018: Noncontrast computed tomography factors predictive of extracorporeal shock wave lithotripsy outcomes in patients with pancreatic duct stones.
Liu R, Su W, Gong J, Zhang Y, Lu J.
Department of Radiology, Department of Nuclear Medicine, Changhai Hospital Affiliated to the Second Military Medical University, Changhai Road 168, Yangpu District, Shanghai, 200433, People's Republic of China.
PURPOSE: To assess the usefulness of factors unique to NCCT for the prediction of ESWL outcomes in patients with pancreatic duct stones.
MATERIALS AND METHODS: We retrospectively evaluated 148 patients with multiple PDS who had undergone ESWL therapy. All patients received an examination for NCCT both before and after ESWL. The following parameters were measured and recorded: patient characteristics including sex and age; NCCT parameters including mean stone length, mean stone volumes before and after ESWL, mean value of CT attenuation, standard deviation of CT attenuation, variation coefficient of CT attenuation, skin-to-stone distance, and pancreatic duct diameter; ESWL outcome indexes including stone clearance rate calculated using the formula [Formula: see text], and the number of ESWL sessions. All patients were divided into groups based on their SCR: A group (SCR ≥ 90%), B group (SCR between 50% and 90%), and C group (SCR < 50%). Analysis of variance was used among the three groups to evaluate the potential predictors of SCR, and a receiver-operating curve was established to determine the optimal cutoff value.
RESULTS: ANOVA analysis revealed that MSD was the only significant predictor for SCR (p < 0.05), and ROC indicated an optimal cutoff value of +1000.45 HU, with a sensitivity up to 78.0% and specificity of 48.6%. Stones with MSD lower than +1000.45 HU had higher SCR (69.3%) than that of higher-density ones (59.6%). Pearson correlation analysis and histogram indicated a significant positive correlation between ESWL No. and MSL (r = 0.536), MSD (r = 0.250), SDSD (r = 0.247), and PDD (r = 0.227), all values being p < 0.01.
CONCLUSION: MSD is the optimal predictor of ESWL efficacy, and PDS with lower MSD had a better clearance rate with fewer fragmentation sessions.
Abdom Radiol (NY). 2018 May 15. doi: 10.1007/s00261-018-1639-4. [Epub ahead of print]. FREE ARTICLE
As SWL-treatment of pancreatic duct stones commonly are placed in the hands of the urologist responsible for the lithotripsy service, reading this report might turn out to be useful.
The article is based on NCCT data before and after SWL carried out in 148 patients. Although the authors state that their results were based on a sufficiently large number of patients, they nevertheless suggest more extensive studies. There might, however, be few centres that come up to this number of patients with stones in the pancreatic duct qualified for SWL.
The pancreatic stones in this population were large with a mean stone volume of ~5200 mm3, also including multiple stones. It is of note that the average number of SWL-sessions was 2.4 with up to 8 sessions required for successful clearance in the most severe cases.
Nothing is mentioned about the stone composition, but according to the reviewer’s experience, dominance of calcium carbonate usually makes disintegration easy (at least with the Dornier HM3 lithotripter). Important to realize for this group of patients, however, is the great influence of the condition of the pancreatic duct.
The bottom-line of the analysis is that the only significant predictor of stone clearance was the mean stone density and that a cut off at 1000 HU had a sensitivity of 98% and specificity of 49%.
For the readers who only have access to the Abstract; below follows an explanation of the abbreviations used:
PDS pancreatic duct stone
SCR stone clearance rate
MSD mean stone attenuation
SDSD standard deviation of MSD
MSL mean of maximal and shortest diameters
MST mean stone length
PDD pancreatic duct diameter
Vo preoperative stone volume
Vi postoperative stone volume