[1] Department of Diagnostic Radiology,
[2] Free University Hospital,undefined
[3] Amsterdam,undefined
[4] P. O. Box 7057,undefined
[5] 1007 MB Amsterdam,undefined
[6] The Netherlands,undefined
[7] Department of Pediatric Surgery,undefined
[8] Free University Hospital,undefined
[9] Amsterdam,undefined
[10] P. O. Box 7057,undefined
[11] 1007 MB Amsterdam,undefined
[12] The Netherlands,undefined