Contributions of an adiabatic initial inversion pulse and K-space re-ordered by inversion-time at each slice position (KRISP) to control of CSF artifacts anti visualization of the brain in FLAIR magnetic resonance imaging

AIM: The aim of this study was to compare the performance of three fluid at tenuated inversion recovery (FLAIR) pulse sequences for control of cerebros pinal fluid (CSF) and blood how artifacts in imaging of the brain. The firs t of these sequences had an initial sine inversion pulse which was followed by conventional k-space mapping. The second had an initial sine inversion pulse followed by k-space re-ordered by inversion time at each slice positi on (KRISP) and the third had an adiabatic initial inversion pulse followed by KRISP. MATERIALS AND METHODS: Ten patients with established disease were studied w ith all three pulse sequences. Seven were also studied with the adiabatic K RISP sequence after contrast enhancement. Their images were evaluated for p atient motion artifact, CSF and blood pow artifact as well as conspicuity o f the cortex, meninges, ventricular system, brainstem and cerebellum. The c onspicuity of lesions and the degree of enhancement were also evaluated. RESULTS: Both the sine and adiabatic KRISP FLAIR sequences showed better co ntrol of CSF and blood flow artifacts than the conventional FLAIR sequence. In addition the adiabatic KRISP FLAIR sequence showed better control of CS F artifact at the inferior aspect of the posterior fossa. The lesion conspi cuity was similar for each of the FLAIR sequences as was the degree of cont rast enhancement to that shown with a T, weighted spin echo sequence. CONCLUSION: The KRISP FLAIR sequence controls high signal artifacts from CS F flow and blood how and the adiabatic pulse controls high signal artifacts due to inadequate inversion of the CSF magnetization at the periphery of t he head transmitter coil. The KRISP FLAIR sequence also improves cortical a nd meningeal definition as a result of an edge enhancement effect. The effe cts are synergistic and can be usefully combined in a single pulse sequence . (C) 2001 The Royal College of Radiologists.