Radiology, Vol 177, 147-151, Copyright © 1990 by Radiological Society of North America
Intact stones or fragments? Potential pitfalls in the imaging of patients after biliary extracorporeal shock wave lithotripsy [published erratum appears in Radiology 1991 Feb;178(2):584]
MR Khouri, JB Goldszmidt, I Laufer, P Arger, A Marcus, F Wisniewski, O Ekberg, PF Malet and O] Okberg O$[corrected to Ekberg
Department of Medicine, University of Pennsylvania, Philadelphia.
Ultrasound is used after extracorporeal shock wave lithotripsy of
gallbladder stones to assess fragmentation. In many patients with
apparently successful fragmentation, the posttreatment studies show an
intraluminal, echogenic focus within the gallbladder, with posterior
acoustic shadowing characteristic of an intact stone. Cholesterol
gallstones were fragmented in vitro by means of lithotripsy, and the
sonographic appearance of the fragmented stones was followed up over time
to study factors that might affect the process. After lithotripsy,
fragments settled and produced an echogenic focus with posterior shadowing
indistinguishable from the appearance of an intact stone. These
experimental observations led to the development of a clinical maneuver to
overcome the diagnostic pitfalls posed by the reaggregation of stone
fragments in situ. This rollover maneuver helps distinguish between intact
stones and fragments, and prevents both diagnostic errors in follow-up and
unnecessary retreatment.
