MRI Pulse Sequences- ARRT Review Questions and Answers with Certified Solutions

MRI Pulse Sequences- ARRT Review Questions and Answers with Certified Solutions What is the primary purpose of a spin-echo sequence in MRI? To reduce artifacts and provide high-quality T1 and T2 contrast How does a fast spin-echo (FSE) sequence reduce scan time? By acquiring multiple echoes per repetition time (TR) Why is gradient echo imaging faster than spin-echo imaging? It does not use a 180-degree refocusing pulse, reducing TR What is the main advantage of inversion recovery sequences? They allow selective suppression of specific tissues, such as fat or fluid How does a short TI inversion recovery (STIR) sequence work? It nulls fat signal for better lesion detection 2 Why is fluid-attenuated inversion recovery (FLAIR) used in brain imaging? To suppress cerebrospinal fluid (CSF) and highlight pathology What happens to T1 contrast when TR is increased? T1 contrast decreases, making tissues appear more similar Why are gradient-recalled echo (GRE) sequences prone to susceptibility artifacts? They lack a refocusing pulse, making them sensitive to magnetic field inhomogeneities How does echo planar imaging (EPI) achieve rapid image acquisition? It collects multiple echoes within a single TR using fast gradient switching What is the benefit of using a balanced steady-state free precession (bSSFP) sequence? It provides high signal from fluids, making it useful for cardiac and abdominal imaging Why are spoiled gradient echo sequences used in MRI? They remove residual transverse magnetization to improve T1 contrast 3 What is the purpose of diffusion-weighted imaging (DWI)? To detect differences in water movement, useful for stroke and tumor evaluation How does increasing echo train length (ETL) in fast spin-echo affect images? It shortens scan time but can cause blurring Why is cardiac gating used in cine MRI sequences? To synchronize imaging with the heart’s motion and reduce motion artifacts What is the effect of increasing flip angle in gradient echo imaging? It enhances T1 contrast but can reduce overall signal Why are dual-echo sequences useful in MRI? They provide both proton density and T2-weighted images in a single acquisition How does susceptibility-weighted imaging (SWI) enhance tissue contrast? It uses phase differences to highlight magnetic susceptibility variations 4 Why is turbo spin-echo (TSE) preferred over conventional spin-echo? It reduces scan time while maintaining T2 contrast How does increasing the number of slices in a 3D sequence affect image quality? It improves spatial resolution but may require