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SU-E-I-69: Magnetic Resonance Metal Artifact Evaluation with Routine Clinical Cardiac Sequences.

Abstract：

PURPOSE:To examine schemes to grade the severity of metal susceptibility artifacts on image quality using cardiac MRI pulse sequences. METHODS:A post-thoracotomy patient was simulated with a stainless steel sternal wire (Syneture,MA; size=6, diameter=48mm), placed securely on an ACR MRI phantom. Phantom was scanned on a 1.5-T Siemens using cardiac MRI sequences:1)TrueFISP, 2)Gradient-Recalled-Echo (GRE), 3)Turbo-Spin- Echo (TSE), 4)Turbo-Inversion-Recovery-Magnitude (TIRM), 5)Dark- blood-IR-FS (DBFS) with and without the wire (FOV=30×30cm, slice- thickness/slice-gap=7.0/1.5mm, matrix size=192×192, slices=17). Image quality degradation was assessed in terms of signal loss and spatial deformation; signal loss by a) measuring the largest diameter of signal drop and b) number of slices with a signal drop and spatial deformation in VelocityAI (Atlanta,GA) by computing the rigid transformation indices between the phantom's internal grid with and without the metal. RESULTS:Image quality was evaluated in terms of signal loss, spatial deformation and ring artifacts. Signal loss: TruFISP and GRE showed the largest signal drop diameter (13 and 16cm respectively). GRE sequence showed a signal drop in -12 slices where as signal drop occurred in only ∼4-5 slices with other sequences. Spatial deformation: GRE sequence showed the maximum with a ∼9mm grid deflection followed by TSE and DBFS (∼8mm). An average deflection of 5.4mm was observed on most of the sequences except T rueFISP and TIRM (Omm). Rigid body transformation showed a maximum x,y,z-translation of -4.7, 0.3 and 1.69 mm and x,y,z-angular rotation of 0.2, - 1.5 and 0.5° for GRE sequence followed by TSE and DBFS confirming the spatial distortion results. Concentric ring artifacts with signal loss were also observed on TrueFISP and DBFS images. CONCLUSIONS:Quantification of cardiac MR sequences to metal tolerance and the impact on image quality has shown that GRE and TrueFISP are the most metal-susceptible and TIRM is the most metal-tolerant sequence in terms of both signal loss and spatial deformation. This study helped in creating a separate cardiac metal protocol comprising of mainly metal-tolerant sequences thus reducing scan time and patient discomfort.

journal_name

Med Phys

journal_title

Medical physics

authors

Joyner D,Rivard A,Craft D,Liu T,Callaway S,James J

doi

10.1118/1.4734785

subject

Has Abstract

pub_date

2012-06-01 00:00:00

pages

3640-3641

issue

6Part5

eissn

0094-2405

issn

2473-4209

journal_volume

pub_type

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SU-E-I-69: Magnetic Resonance Metal Artifact Evaluation with Routine Clinical Cardiac Sequences.