Defects　in　the　seal　area　of　flexible　packages　bring　out　health　hazards　and　economic　loss.　The　ultrasonic　Backscattered　Echo　Envelope　Integral　(BEEI)　imaging　technique　has　been　used　to　detect　the　seal　integrity　of　hermetically　sealed　flexible　packages.　This　technique　was　able　to　reliably　inspect　channel　defects　as　small　as　50μm　in　diameter　in　the　seal　area　of　flexible　packages.　The　study　of　experimental　spatial　sampling　for　the　BEEI-mode　imaging　technique　was　presented.　Channel　defects　ranging　from　50　to　150μm　in　diameter　embedded　in　bonded　2-sheet　polyethylene　film　were　used　for　sample.　An　immersion　spherically　focused　transducer　(center　frequency　of　22.66　MHz)　scanned　over　sample　with　a　static　rectilinear　stop-and-go　scanning　pattern　and　acquired　echo　data　in　varying　scanning　step　from　each　sample.　Two　descriptors,　the　average　BEEI　value　difference　(ΔBEEI)　between　defected　and　intact　regions　and　contrast-to-noise　ratio　(CNR),　were　defined　to　quantitatively　assess　the　BEEI-mode　image　quality　versus　varying　scanning　step　size　and　varying　sized　defects.　For　any　given　defects,　the　ΔBEEI　and　CNR　degraded　as　scanning　step　size　increased.　Detailed　imaging　of　defects　can　be　acquired　when　the　step　size　is　small　than　echo　focal　beam　diameter,　and　the　image　become　partial　or　completely　distorted　when　the　step　size　exceeds　twice　of　the　beam　diameter.　©　2009　SPIE.