In addition, the visualization of the needles in the MR environment is connected directly to the principal phenomena, called susceptibility artifacts, caused by needle-induced field inhomogeneities in the MR image. They have focused on the safety, performance success, and visualization of the needles relative to surrounding tissues. There have been continuous efforts, which have concentrated on developing strategies for MR-guided biopsies.
The recent commercial availability of open MR systems has become the preferred type for MRI-guided procedures because it provides direct access to the patient.
An MRI-guided biopsy is performed using either an open- or closed-bore MRI system. As a consequence, it does not allow the precise placement of the needle within the MRI scan. Despite the benefits of using MRI-compatible needles, it is still challenging due to severe susceptibility artifacts appearing during the MRI scan because of the material’s interactions with the magnetic field. In this context, most standard needles for interventions are limited for use in the MRI environment due to safety concerns related to a magnetic attraction. Interventional needles used in MRI-guided procedures must meet the essential requirements of electromagnetic compatibility and the avoidance of mechanical forces due to magnetic attraction. However, performing image-guided procedures in an MRI environment can be challenging due to the presence of a strong magnetic field. K-means provided the capability for detecting needle artifacts in MRI images, facilitating qualitative and quantitative assessment of MRI artifacts. The non-metallic needles showed significantly lower artifacts in comparison to the standard needle. The width and length of the artifacts were measured for each needle.
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Susceptibility artifacts for the non-metallic needles were evaluated in MRI images by an automatic quantification based on a K-means algorithm and compared with manual quantification. Hence, this work used a new combination of non-metallic materials based on an enforced fiber bundle as an inner core with different outer hollow sheets to fabricate seven prototypes of interventional spinal needles to optimize their visualization in MRI scans. The aim was to prove that using a non-metallic material for the needle can significantly reduce the appearance of artifacts. Consequently, this does not allow the precise placement of the needle to the target. In particular, standard needles for the spinal cord made of nickel-titanium alloys (NiTi) generate massive susceptibility artifacts during MRI. In this context, severe susceptibility artifacts affect the visibility of structures in the MR images depending on the needle’s material composition. Interventional biopsy needles need to be accurately localized to the target tissue during magnetic resonance imaging (MRI) interventions.
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