count the number of times that patient 11426 had received contr cerebr arteriogram until 3 years ago.
select count(*) from procedures_icd where procedures_icd.icd9_code = ( select d_icd_procedures.icd9_code from d_icd_procedures where d_icd_procedures.short_title = 'contr cerebr arteriogram' ) and procedures_icd.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 11426 ) and datetime(procedures_icd.charttime) <= datetime(current_time,'-3 year')