A diffusion-prepared reduced FOV sequence for prostate MRI near metallic implants
Philip K Lee1, Jeremiah J Hess1,2, Andrew A Gomella1
1Radiology, Stanford University, Stanford, California, USA.
Purpose:
To enable diffusion weighted imaging in prostate patients with metallic total hip replacements in clinically feasible scan times for prostate cancer screening, and avoid distortion and dropout artifacts present in the conventionally used Echo Planar Imaging (EPI).
Methods:
A reduced field of view (FOV) diffusion-prepared sequence that is robust to the B inhomogeneities produced by total hip replacements was achieved using high radiofrequency (RF) bandwidth pulses and manipulation for stimulated echo pathways. The reduced FOV along the A/P direction was obtained using slice-select gradient reversal, and the prepared magnetization was imaged with a three-dimensional RF-spoiled gradient echo readout. The sequence was validated in phantom experiments, in vivo in healthy volunteers with and without total hip replacements, and in vivo in patients undergoing a standard MRI prostate exam.
Results:
The proposed sequence is robust to shading and distortion artifacts that are encountered by standard diffusion-weighted EPI in the presence of moderate off-resonance. Apparent diffusion coefficient estimates obtained by the proposed sequence were comparable to those obtained with diffusion-weighted EPI.
Conclusion:
Acquisition of distortionless diffusion weighted images of the prostate is feasible in patients with total hip replacements on conventional, whole-body 3T MRI, using a b-value of 800 and nominal resolution of 1.7 1.7 4 mm3 in scan times of 6 min.
Insights
A new diffusion imaging technique allows for clear prostate cancer screening in patients with hip implants, overcoming common MRI artifacts. This method achieves distortionless images in just 6 minutes.
Area of Science:
- Radiology
- Medical Imaging
- Prostate Cancer Diagnostics
Background:
- Metallic total hip replacements (THRs) cause artifacts in standard diffusion-weighted imaging (DWI) for prostate MRI.
- Echo Planar Imaging (EPI), commonly used for DWI, is particularly susceptible to distortion and signal dropout near THRs.
Purpose of the Study:
- To develop a diffusion-weighted imaging (DWI) sequence for prostate cancer screening in patients with metallic total hip replacements (THRs).
- To achieve clinically feasible scan times while avoiding artifacts common with conventional Echo Planar Imaging (EPI).
Main Methods:
- A reduced field of view (FOV) diffusion-prepared sequence utilizing high radiofrequency (RF) bandwidth pulses and stimulated echo pathways was developed.
- Slice-select gradient reversal created a reduced FOV, and a 3D RF-spoiled gradient echo readout imaged the prepared magnetization.
- The sequence was validated in phantoms, healthy volunteers (with/without THRs), and patients undergoing prostate MRI.
Main Results:
- The proposed sequence demonstrated robustness against shading and distortion artifacts in the presence of off-resonance, unlike standard DWI-EPI.
- Apparent diffusion coefficient (ADC) estimates from the new sequence were comparable to those from conventional DWI-EPI.
Conclusions:
- Distortionless diffusion-weighted imaging of the prostate is achievable in patients with THRs using conventional 3T MRI.
- The technique allows for prostate cancer screening with a b-value of 800 s/mm², 1.7x1.7x4 mm³ resolution, in a 6-minute scan time.
More Related Videos
Related Concept Videos
01:24Magnetic Resonance Imaging
01:14Imaging Studies I: CT and MRI
Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...