2140
Intra - operative ultrasound ( IOUS ) has been widely used in an attempt to overcome these difficulties , but is limited by its two - dimensional nature , inter - user variability , and image obliteration with ablative or resectional techniques .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities:  
Answer:
 None