Assuntos
Dor nas Costas/diagnóstico por imagem , Dor nas Costas/etiologia , Ependimoma/complicações , Ependimoma/diagnóstico por imagem , Transtornos do Sono-Vigília/etiologia , Neoplasias da Medula Espinal/complicações , Neoplasias da Medula Espinal/diagnóstico por imagem , Vértebras Torácicas/diagnóstico por imagem , Adulto , Diagnóstico Diferencial , Ependimoma/cirurgia , Pé/inervação , Humanos , Hipestesia/diagnóstico por imagem , Hipestesia/etiologia , Imageamento por Ressonância Magnética , Masculino , Transtornos do Sono-Vigília/diagnóstico por imagem , Neoplasias da Medula Espinal/cirurgiaRESUMO
OBJECTIVE: The improvement in Arterial Spin Labeling (ASL) perfusion quantification, especially for delayed bolus arrival times (BAT), with an acquisition redistribution scheme mitigating the T1 decay of the label in multi-TI ASL measurements is investigated. A multi inflow time (TI) 3D-GRASE sequence is presented which adapts the distribution of acquisitions accordingly, by keeping the scan time constant. MATERIAL AND METHODS: The MR sequence increases the number of averages at long TIs and decreases their number at short TIs and thus compensating the T1 decay of the label. The improvement of perfusion quantification is evaluated in simulations as well as in-vivo in healthy volunteers and patients with prolonged BATs due to age or steno-occlusive disease. RESULTS: The improvement in perfusion quantification depends on BAT. At healthy BATs the differences are small, but become larger for longer BATs typically found in certain diseases. The relative error of perfusion is improved up to 30% at BATs>1500ms in comparison to the standard acquisition scheme. CONCLUSION: This adapted acquisition scheme improves the perfusion measurement in comparison to standard multi-TI ASL implementations. It provides relevant benefit in clinical conditions that cause prolonged BATs and is therefore of high clinical relevance for neuroimaging of steno-occlusive diseases.