Study　Design:　A　prospective　study.　Purpose:　To　assess　fat–water-like　tissue　changes　on　the　1st　sacral　vertebra　using　novel　magnetic　resonance　imaging　(MRI)　phantom-based　F-　and　W-scores　and　evaluate　their　diagnostic　performances　in　osteoporosis　detection.　Overview　of　Literature:　Using　an　uncommonly　advanced　MRI　technique,　previous　studies　have　found　that　fat–water　changes　were　consistent　with　osteoporosis.　The　role　of　routine　MRI　sequences　can　be　extended　in　this　regard.　The　S1　vertebra　is　considered　a　crucial　anatomical　site　in　spine　surgeries　because　it　seldom　suffers　from　fractures.　Thus,　S1　could　indicate　osteoporotic　fat–water　changes.　Methods:　Forty-two　female　volunteers　(aged　62.3±6.3　years)　underwent　spine　examination　with　both　MRI　(including　a　phantom)　and　dual-energy　X-ray　absorptiometry　(DXA)　following　ethical　approval.　MRI　phantom-based　F-　and　W-scoreS1　were　defined　by　normalizing　S1　vertebral　signal　intensities　(SIs)　by　coconut　oil　and　water　SIs　of　the　phantom　on　T1-　and　T2-weighted　imaging,　respectively.　Using　receiver　operating　characteristic　analysis,　the　diagnostic　performances　of　the　new　scores　for　evaluating　osteoporosis　and　vertebral　fractures　were　investigated　against　standard　areal　bone　mineral　density　measured　with　DXA　(DXA-aBMD).　Results:　The　F-scoreS1　and　W-scoreS1　were　greater　(4.11　and　2.43,　respectively)　in　patients　with　osteoporosis　than　those　without　osteoporosis　(3.25　and　1.92,　respectively)　and　achieved　areas　under　the　curve　(AUCs)　of　0.82　and　0.76　(p＜0.05),　respectively,　for　osteoporosis　detection.　Similarly,　the　mean　F-scoreS1　and　W-scoreS1　were　higher　(4.11　and　2.63,　respectively)　in　patients　with　vertebral　fractures　than　in　those　without　fractures　(3.30　and　1.82,　respectively)　and　had　greater　AUCs　(0.90　for　W-scoreS1　and　0.74　for　F-scoreS1)　than　DXA-aBMD　(AUC,　0.26;p＜0.03).　In　addition,　the　F-　and　W-scoreS1　demonstrated　a　strong　correlation　(r=0.65,　p＜0.001).　Conclusions:　The　new　S1　vertebral-based　MRI　scores　were　developed　to　detect　osteoporotic　changes　and　demonstrated　improvements　over　DXA-aBMD　in　differentiating　patients　with　vertebral　fractures.　©　(2024),　(Korean　Society　of　Spine　Surgery).　All　rights　reserved.