Determining a reliably visible and inexpensive surface fiducial marker for use in MRI: a research study in a busy Australian Radiology Department

Abstract

ObjectivesSingle-use commercial surface fiducial markers are used in clinical imaging for a variety of applications. The current study sought to find a new, reliably visible, easily sourced and inexpensive fiducial marker alternative for use with MRI.DesignFive commonly requested MRI sequences were determined (three-dimensional (3D) T1-weighted, T1 coronal, 3D T2-weighted, T2 fat suppressed, proton density), to examine the visibility of 18 items (including a commercial fiducial marker).SettingClinical 3T MRI scanner in an Australian Tertiary Hospital and an Australian University Biomedical Engineering research group.Interventions18 marker alternatives were scanned using five common MRI sequences. Images were reformatted to obtain both an image through the mid-height of each marker and a maximum intensity z-projection image over the volume of the marker. Variations in marker intensity were profiled across each visible marker and a visibility rating defined.Main outcome measuresOutcome measures were based on quantitative assessment of a clear intensity contrast ratio between the marker and the adjacent tissue and a qualitative assessment of visibility via a 3-point scale.ResultsThe fish oil capsule, vitamin D capsule, paint ball pellet, soy sauce sushi tube and commercial markers were typically visible to a high quality on all the imaging sequences and demonstrated a clear differential in intensity contrast against the adjacent tissue. Other common items, such as plasticine ‘play doh’ and a soft ‘Jelly baby’ sweet, were surprise candidates, demonstrating high-quality visibility and intensity contrast for the 3D T1-weighted sequence.ConclusionsDepending on the basis for referral and MRI sequence chosen, four alternative fiducial markers were determined to be inexpensive, easily sourced and consistently visible. Of these, the vitamin D capsule provided an excellent balance between availability, size, cost, usability and quality of the visualised marker for all the commonly used MRI sequences analysed.

Predicting spinal profile using 3D non-contact surface scanning: Changes in surface topography as a predictor of internal spinal alignment

“…Once 3DSS was completed, fiducial markers were overlaid on the surface stickers and attached with surgical tape (Fig 2B). The fiducial markers were Vitamin D capsules which have recently been shown to provide excellent intensity contrast for MRI scanning [16]. Fiducial markers highlighted the same anatomical landmarks on the MR images as the surface markers, permitting registration of points and point clouds from both imaging modalities.…”

Design, Development, and Operation of a Low-Intensity Focused Ultrasound Pulsation (LIFUP) System for Clinical Use

“…The transducers have a unique feature to assist with the alignment process. Two rings of highly MRIvisible material [26] are built into the back of the transducer (Styrene block polymer). Additional material is placed in the center of the screw that holds the back of the transducer (Figure 4B).…”

Predicting spinal column profile from surface topography via 3D non-contact surface scanning

“…Firstly, the external spine surface contour was demarcated using fiducial markers adhered to the skin over the spinous processes. The fiducial markers were vitamin capsules found to be clearly visible in the MR images [ 16 ]. The positions of the fiducial markers and spinous processes were then identified from MRI to calculate a fiducial marker profile (FMP) and the spinal column profile (SCP) .…”