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
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 None