INTRO: Unrecognized solid debris within pancreatic collections predisposes to infection since standard pseudocyst drainage techniques fail to remove this tissue. We sought to determine the comparative utility of MRI ,CT and US to predict successful evacuation of collections by standard pseudocyst drainage techniques. METHODS: From 1/95 to 8/96, 43 pts. underwent drainage of symptomatic pancreatic collections. Because of limited MRI availability, 20 pts. underwent MRI, CT, & US prior to drainage. Each exam was independently interpreted by one of three experienced radiologists without knowledge of collection contents by any other imaging study. Predicted non-drainability using endoscopic pseudocyst drainage techniques was defined on imaging studies as visible non-liquid tissue ≥1cm not exhibiting blood characteristic. Two pts. excluded from analysis for: failed entry (1), pt. refusal (1). Collections were drained endoscopically (E) in 14, percutaneously (P) in 1, P+E in 1, E + Surgically (S) in 1, and S alone in 1. Accuracy of each imaging method was compared to the other two using t-test for ordinal data, sample size 5≤N≤20. RESULTS: 19 collections (18 pts.) were evaluated. All 19 were identified by MRI and CT; US failed to visualize two. Eight collections were not drainable using standard pseudocyst drainage techniques and required multiple IOFR catheters with saline lavage ± surgery/percutaneous therapy. Eleven collections were drainable using standard pseudocyst drainage techniques (7 or 10FR catheters only). No. (%) CORRECTLY PREDICTED STANDARD PSEUDOCYST DRAINAGE THECHOQUES - OUTCOME MRI CT US NOT DRAINABLE (N=8) [SENSITIVITY] 8 (100%)* 2 (25)* 7 (88%) DRAINABLE (N=11) [SPECIFICITY) 11 (100%)* 11 (100%) 4 (54%)* * p < 0.01 CONCLUSIONS: 1) By identifying solid debris, MRI is significantly more sensitive than CT in predicting non-drainability of pancreatic collections using standard pseudocyst drainage techniques 2) By identifying absence of solid debris, MRI is significantly more specific than US in predicting successful drainability of pancreatic collections using standard pseudocyst drainage techniques 3) MRI of pancreatic collections should be performed prior to attempted drainage to better predict the likelihood of successful therapy using standard pseudocyst drainage techniques.