Filter response values

I am using following API call - VisitsSummary.get

I don’t want all the data that comes with the response, like
[max_actions]
[nb_actions]
[nb_uniq_visitors]
[nb_visits]
[sum_visit_length]
[bounce_rate]
[nb_actions_per_visit]
[avg_time_on_site]

I just want following one
[nb_visits]

How can I modify the API call