Evaluation of a Modified Stejskal-Tanner Diffusion Encoding Scheme, Permitting a Marked Reduction in TE, in Diffusion-Weighted Imaging of Stroke Patients at 3 T

Purpose:To evaluate a modified Stejskal-Tanner diffusion gradient pulsing scheme that applies diffusion encoding during the entire time between the 2 requisite radiofrequency pulses, shortening TE. Materials and Methods:Seventeen healthy volunteers and 15 patients with acute and early subacute infarcts were evaluated at 3 T utilizing: a conventional bipolar gradient double spin echo planar imaging diffusion weighted imaging with a parallel imaging factor of 2 (p2) and a modified Stejskal-Tanner short TE (sTE) SE echo planar imaging diffusion weighted imaging with parallel imaging factors of 2, 3, and 4. Signal-to-noise ratio (SNR) and susceptibility-induced spatial distortions were quantified, and a blinded reader ranked scans in terms of susceptibility artifact and overall preference. Results:The sTE sequence allowed a shortening in TE of 18 to 28 milliseconds versus the standard bipolar gradient sequence. SNRs were generally not significantly different among the sTE scans because of compensation by number of scan averages. By using twice the number of averages, the SNR with the bipolar gradient sequence was not significantly different from that of the sTE sequences in patients. sTE scans with higher parallel imaging factors demonstrated less susceptibility-related artifact. The blinded reader ranked the p3 or p4 sTE scans most preferred and the bipolar gradient scans least or tied for least preferred in every case. Conclusions:Utilization of the sTE modified Stejskal-Tanner sequence markedly improves SNR—an increase that may be used with parallel imaging to improve overall scan quality whereas maintaining reasonable scan times and SNR.

[1]  J. Michael Fitzpatrick,et al.  A technique for accurate magnetic resonance imaging in the presence of field inhomogeneities , 1992, IEEE Trans. Medical Imaging.

[2]  C. Claussen,et al.  Tumor Detection by Diffusion-Weighted MRI and ADC-Mapping—Initial Clinical Experiences in Comparison to PET-CT , 2007, Investigative radiology.

[3]  Stephan G Wetzel,et al.  The clinical significance of diffusion-weighted MR imaging in stroke and TIA patients. , 2008, Swiss medical weekly.

[4]  D. Parker,et al.  Elimination of eddy current artifacts in diffusion‐weighted echo‐planar images: The use of bipolar gradients , 1997, Magnetic resonance in medicine.

[5]  Val M. Runge,et al.  Brain Magnetic Resonance Imaging at 3 Tesla Using BLADE Compared With Standard Rectilinear Data Sampling , 2006, Investigative radiology.

[6]  J. Finsterbusch.  Eddy‐current compensated diffusion weighting with a single refocusing RF pulse , 2009, Magnetic resonance in medicine.

[7]  V. Wedeen,et al.  Reduction of eddy‐current‐induced distortion in diffusion MRI using a twice‐refocused spin echo , 2003, Magnetic resonance in medicine.

[8]  J. E. Tanner,et al.  Spin diffusion measurements : spin echoes in the presence of a time-dependent field gradient , 1965 .

[9]  Diffusion-Weighted Imaging in Patients With Acute Brain Ischemia at 3 T: Current Possibilities and Future Perspectives Comparing Conventional Echoplanar Diffusion-Weighted Imaging and Fast Spin Echo Diffusion-Weighted Imaging Sequences Using BLADE (PROPELLER) , 2009, Investigative radiology.

[10]  P. Hunold,et al.  MR Evaluation of Left Ventricular Volumes and Function: Threshold-Based 3D Segmentation Versus Short-Axis Planimetry , 2009, Investigative radiology.

[11]  J. van Gijn,et al.  Clinical practice. Acute ischemic stroke. , 2007, The New England journal of medicine.

[12]  A M Takahashi,et al.  ADC mapping by means of a single‐shot spiral MRI technique with application in acute cerebral ischemia , 1999, Magnetic resonance in medicine.

[13]  R. Henkelman.  Measurement of signal intensities in the presence of noise in MR images. , 1985, Medical physics.

[14]  C. Tempelmann,et al.  Eddy current correction in diffusion‐weighted imaging using pairs of images acquired with opposite diffusion gradient polarity , 2004, Magnetic resonance in medicine.

[15]  S. Schoenberg,et al.  Practical approaches to the evaluation of signal‐to‐noise ratio performance with parallel imaging: Application with cardiac imaging and a 32‐channel cardiac coil , 2005, Magnetic resonance in medicine.

[16]  B. K. Park,et al.  Lesion Localization in Patients With a Previous Negative Transrectal Ultrasound Biopsy and Persistently Elevated Prostate Specific Antigen Level Using Diffusion-Weighted Imaging at Three Tesla Before Rebiopsy , 2008, Investigative radiology.

[17]  Robin M Heidemann,et al.  High resolution diffusion‐weighted imaging using readout‐segmented echo‐planar imaging, parallel imaging and a two‐dimensional navigator‐based reacquisition , 2009, Magnetic resonance in medicine.

[18]  L H Schwamm,et al.  Diffusion-weighted MR imaging: diagnostic accuracy in patients imaged within 6 hours of stroke symptom onset. , 1999, Radiology.

[19]  Aaron Fenster,et al.  Hyperpolarized 3He Ventilation Defects and Apparent Diffusion Coefficients in Chronic Obstructive Pulmonary Disease: Preliminary Results at 3.0 Tesla , 2007, Investigative radiology.

[20]  A. Demchuk,et al.  When to Expect Negative Diffusion-Weighted Images in Stroke and Transient Ischemic Attack , 2008, Stroke.

[21]  A. Larson,et al.  Multishot Targeted PROPELLER Magnetic Resonance Imaging: Description of the Technique and Initial Applications , 2009, Investigative radiology.

[22]  Andrew C Larson,et al.  Multishot Diffusion-Weighted PROPELLER Magnetic Resonance Imaging of the Abdomen , 2006, Investigative radiology.

[23]  Wilhelm Horger,et al.  Black-Blood Diffusion-Weighted EPI Acquisition of the Liver with Parallel Imaging: Comparison with a Standard T2-Weighted Sequence for Detection of Focal Liver Lesions , 2008, Investigative radiology.

[24]  Ulrike I Attenberger,et al.  Diffusion Weighted Imaging: A Comprehensive Evaluation of a Fast Spin Echo DWI Sequence With BLADE (PROPELLER) k-Space Sampling at 3 T, Using a 32-Channel Head Coil in Acute Brain Ischemia , 2009, Investigative radiology.

[25]  R. Stollberger,et al.  Improved diffusion‐weighted single‐shot echo‐planar imaging (EPI) in stroke using sensitivity encoding (SENSE) , 2001, Magnetic resonance in medicine.