Influence of gold marker for magnetic resonance imaging during prostate radiotherapy

Abstract

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.

Radiotherapy for prostate cancer: Effect of gold fiducial markers on diffusion‐weighted magnetic resonance imaging

“…ADC value can be theoretically calculated as a quantitative value when the ROI remains the same both before and after placement. When the presence of metal hinders patient movement or disrupts magnetic field during examinations, the image is often distorted 11‐13 . Moreover, when magnetic susceptibility affects ADC, therapeutic effect may be difficult to determine based on the image.…”

“…Parameters established in previous studies were used, 11,14,15 except for field of view, which was different from that used in routine MRI. We focused on the clarity of the prostate and surrounding structures.…”

“…Compared with the normal prostate, cancerous prostatic tissue demonstrates higher signal intensity on DWI and lower ADC value. Parameters of DWI were the same as those described previously 11 : spin echo with echo planner image [TR/TE in ms]: 2264/70; NSA: eight times; PES: 103; FES:128; TPR; frequency/phase:2.58/3.21; and diffusion b‐factor: 1000 s/mm 2 .…”

“…have reported significant correlations between decreased PSA level and increased apparent diffusion coefficient (ADC) at the site of the prostate cancer in diffusion‐weighted imaging (DWI)6 months following radiotherapy 3 . An increasing number of studies have reported a significant correlation between ADC and PSA level in the assessment of the efficacy of radiotherapy for prostate cancer using DWI 1‐11 …”

“…However, when fiducial markers are placed in the prostate, their size and iron content may affect image quality 7‐12 . DWI is easily affected by metals; it is therefore important to assess whether marker placement decreases image quality, as MRI may be performed after radiotherapy to monitor disease status 5,8 .…”