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Influence of gold marker for magnetic resonance imaging during prostate radiotherapy

Tanaka O., Komeda H., Hirose S., Taniguchi T., Ono K., Yama E., Matsuo M.

Polish Journal of Medical Physics and Engineering

2018

Vol. 24, Iss. 3

99--101

Gold markers (GM) are increasingly used for CT and MRI registration during in intensity-modulated radiation therapy for prostate cancer. Additionally, diffusion-weighted imaging has been adopted to measure the effects of radiotherapy for prostate cancer, similar to tests of blood prostate-specific antigen levels. As diffusion-weighted imaging (DWI) is often affected by a magnetic component, we evaluated the influence of GM on the Diffusion weighted images in three cases. We found that the size range of signal void of GM in MRI was 2–5 mm. We conclude that a GM would not affect the quality of DWI in daily practice.

Initial experience of using an iron-containing fiducial marker for radiotherapy of prostate cancer: Advantages in the visualization of markers in Computed Tomography and Magnetic Resonance Imaging

Tanaka O., Iida T., Komeda H., Tamaki M., Seike K., Kato D., Yokoyama T., Hirose S., Kawaguchi D.

Polish Journal of Medical Physics and Engineering

2016

Vol. 22, Iss. 4

93--96

Visualization of markers is critical for imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). However, the size of the marker varies according to the imaging technique. While a large-sized marker is more useful for visualization in MRI, it results in artifacts on CT and causes substantial pain on administration. In contrast, a small-sized marker reduces the artifacts on CT but hampers MRI detection. Herein, we report a new ironcontaining marker and compare its utility with that of non-iron-containing markers. Five patients underwent CT/MRI fusion-based intensity-modulated radiotherapy, and the markers were placed by urologists. A Gold Anchor™ (GA; diameter, 0.28 mm; length, 10 mm) was placed using a 22G needle on the right side of the prostate. A VISICOIL™ (VIS; diameter, 0.35 mm; length, 10 mm) was placed using a 19G needle on the left side. MRI was performed using T2*-weighted imaging. Three observers evaluated and scored the visual qualities of the acquired images. The mean score of visualization was almost identical between the GA and VIS in radiography and cone-beam CT (Novalis Tx). The artifacts in planning CT were slightly larger using the GA than using the VIS. The visualization of the marker on MRI using the GA was superior to that using the VIS. In conclusion, the visualization quality of radiography, conebeam CT, and planning CT was roughly equal between the GA and VIS. However, the GA was more strongly visualized than was the VIS on MRI due to iron containing.