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Visibility of an iron‐containing fiducial marker in magnetic resonance imaging for high‐precision external beam prostate radiotherapy
Author(s) -
Tanaka Osamu,
Komeda Hisao,
Hirose Shigeki,
Taniguchi Takuya,
Ono Kousei,
Matsuo Masayuki
Publication year - 2018
Publication title -
asia‐pacific journal of clinical oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 29
eISSN - 1743-7563
pISSN - 1743-7555
DOI - 10.1111/ajco.12830
Subject(s) - fiducial marker , magnetic resonance imaging , medicine , prostate cancer , nuclear medicine , radiation therapy , prostate , radiology , cancer
Visualization of fiducial gold markers is critical for registration on computed tomography (CT) and magnetic resonance imaging (MRI) for imaging‐guided radiotherapy. Although larger markers provide better visualization on MRI, they tend to generate artifacts on CT. MRI is strongly influenced by the presence of metals, such as iron, in the body. Here we compared efficacies of a 0.5% iron‐containing gold marker (GM) and a traditional non‐iron‐containing marker. Methods Twenty‐seven patients underwent CT/MRI fusion‐based intensity‐modulated radiotherapy. Markers were placed by urologists under local anesthesia. Gold Anchor (GA; diameter: 0.28 mm; length: 10 mm), an iron‐containing marker, was placed on the right side of the prostate using a 22‐G needle and VISICOIL (VIS; diameter: 0.35 mm; length: 10 mm), a non‐iron‐containing marker, was placed on the left side using a 19‐G needle. T2*‐weighted images MRI sequences were obtained. Two radiation oncologists and a radiation technologist evaluated and assigned scores for visual quality on a five‐point scale (1, poor; 5, best visibility). Results Artifact generation on CT was slightly greater with GA than with VIS. The mean marker visualization scores on MRI of all three observers were significantly superior for GA than for VIS (3.5 vs 3.2, 3.9 vs 3.2, and 4.0 vs 2.9). The actual size of the spherical GA was about 2 mm in diameter, but the signal void on MRI was approximately 5 mm. Conclusion Although both markers were well visualized and can be recommended clinically, the results suggest that GA has some subtle advantages for quantitative visualization that could prove useful in certain situations of stereotactic body radiotherapy and intensity‐modulated radiotherapy.