Sentence:  By submerging the patient in a tub and rotating the transducer while the scanning goes on , they have been able to get cross-section views of the neck , as shown in Fig. 7 , as well as many other <WSD>hitherto</WSD> impossible insights . 
Meaning of the word marked with <WSD> tags:  used in negative statement to describe a situation that has existed up to this point or up to the present time