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

OBJECTIVES: Single-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. DESIGN: Five 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). SETTING: Clinical 3T MRI scanner in an Australian Tertiary Hospital and an Australian University Biomedical Engineering research group. INTERVENTIONS: 18 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 MEASURES: Outcome 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. RESULTS: The 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. CONCLUSIONS: Depending 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.

Gold fiducials are a unique marker for localization in the thoracic spine: a cost comparison with percutaneous vertebroplasty.

We present a unique application of the gold fiducial as a preoperative, radiographic marker placed in the thoracic spine and used for intraoperative localization. In comparison to percutaneous vertebroplasty marking of thoracic spinal levels with polymethyl methacrylate (PMMA) cement, implantation of the gold fiducial is technically facile with a minimal learning curve. The fiducial markers are also associated with significantly less financial resources. Following 2013 Current Procedural Terminology (CPT) coding, the cost of vertebroplasty under fluoroscopic guidance, $3195·43, or under computed tomography (CT) guidance, $3232·54, is more than double the cost of the gold fiducial implantation - $1237·55 and $1267·03, under similar imaging techniques, respectively. In the first description of gold fiducials in the thoracic spine, we conclude that the marker is a safe and cost-effective method for preoperative localization of the thoracic levels.