Extracorporeal Shock Wave Lithotripsy on Pancreatic Duct Stones in Patients with Chronic Pancreatitis: Evaluation of Therapeutic Results with CT

ABSTRACT

PURPOSE: To demonstrate by CT scanning the effect of extracorporeal shock wave lithotripsy (ESWL) on pancreatic duct stones in patients with chronic pancreatitis. MATERIALS AND METHODS: Pancreatic duct stones in 11 patients with chronic pancreatitis were subject to ESWL using an electrohydraulic lithotripter. Endoscopic stone removal using a basket had failed in ten patients, and in one, endoscopy was impossible due to a previous Whipple's operation. CT scans obtained before and after ESWL were evaluated by two radiologists the longest and shortest diameters of the target stone were measured, and according to the degree of fragmentation, determined by comparing the area of the stone before and after ESWL, a grade (1-5) was assigned. In each case, the pre- and post- treatment diameter of the main pancreatic duct, measured at the pancreatic body, was also compared. RESULTS: Disintegration of the target stone was achieved in all patients grade 1 (over 75% of the area remained, compared with that of the initial stone) was assigned in two patients; grade 2 (51-75% of the original area) in one; grade 3 (26-50%) in four; grade 4 (under 25%) in two; and grade 5 (complete clearance of the target stone) in two. The mean area decreased from 175 mm2 to 69 mm2 after ESWL (p<0.05); a decrease of more than 50% was observed in eight patients (73%). The mean diameter of the main pancreatic duct decreased from 7.36 to 4.81 mm (p<0.05). No severe adverse effects or complications were noted, and all patients showed clinical improvement. Follow-up studies indicated that pancreatic duct stones recurred in three patients. CONCLUSION: ESWL can cause the fragmentation of pancreatic duct stones without significant complications, and should be considered where endoscopic stone removal has failed. CT is a suitable non-invasive and accurate tool for evaluating the therapeutic results of ESWL.