▁than ▁M RI . ▁Non - contr ast ▁CT ▁is ▁best ▁for ▁ident ifying ▁an ▁ac ute ▁head ▁ble ed . ▁Mag net ic ▁Res on ance ▁Im aging ▁( M RI ) ▁is ▁best ▁for ▁brain ▁tum ors ▁and ▁problems ▁in ▁the ▁posterior ▁f ossa , ▁or ▁back ▁of ▁the ▁brain . ▁M RI ▁is ▁more ▁sensitive ▁for ▁ident ifying ▁int rac ran ial ▁problems , ▁however ▁it ▁can ▁pick ▁up ▁brain ▁ab normal ities ▁that ▁are ▁not ▁relevant ▁to ▁the ▁person ' s ▁head aches . ▁ ▁The ▁American ▁College ▁of ▁Rad i ology ▁recomm ends ▁the ▁following ▁imag ing ▁tests ▁for ▁different ▁specific ▁situations : ▁ ▁L um bar ▁pun ct ure ▁ ▁A ▁lum bar ▁pun ct ure ▁is ▁a ▁procedure ▁in ▁which ▁c ere br al ▁sp inal ▁fluid ▁is ▁removed ▁from ▁the ▁sp ine ▁with ▁a ▁need le . ▁A ▁lum bar ▁pun ct ure ▁is ▁necessary ▁to ▁look ▁for ▁in fection ▁or ▁blood ▁in ▁the ▁sp inal ▁fluid . ▁A ▁lum bar ▁pun ct ure ▁can ▁also ▁evaluate ▁the ▁pressure ▁in ▁the ▁sp inal ▁column , ▁which ▁can ▁be ▁useful ▁for ▁people ▁with ▁id iop ath ic ▁int rac ran ial ▁hy pert ension ▁( us ually ▁young , ▁ob ese ▁women ▁who ▁have ▁increased ▁int rac ran ial ▁pressure ), ▁or ▁other ▁causes ▁of ▁increased ▁int rac ran ial ▁pressure . ▁In ▁most ▁cases , ▁a ▁CT ▁scan ▁should ▁be ▁done ▁first . ▁ ▁Classification ▁ ▁Head aches ▁are ▁most ▁thoroughly ▁class ified ▁by ▁the