An evaluation of three commercially available metal artifact reduction methods for CT imaging

Abstract

Three commercial metal artifact reduction methods were evaluated for use in computed tomography (CT) imaging in the presence of clinically realistic metal implants: Philips O-MAR, GE's monochromatic Gemstone Spectral Imaging (GSI) using dual-energy CT, and GSI monochromatic imaging with metal artifact reduction software applied (MARs). Each method was evaluated according to CT number accuracy, metal size accuracy, and streak artifact severity reduction by using several phantoms, including three anthropomorphic phantoms containing metal implants (hip prosthesis, dental fillings, and spinal fixation rods). All three methods showed varying degrees of success for the hip prosthesis and spinal fixation rod cases, while none were particularly beneficial for dental artifacts. Limitations of the methods were also observed. MARs underestimated the size of metal implants and introduced new artifacts in imaging planes beyond the metal implant when applied to dental artifacts, and both the O-MAR and MARs algorithms induced artifacts for spinal fixation rods in a thoracic phantom. Our findings suggest that all three artifact mitigation methods may benefit patients with metal implants, though they should be used with caution in certain scenarios.

Modeling of the metallic port in breast tissue expanders for photon radiotherapy

“…The measured doses at depths were compared with dose calculations by collapsed cone convolution (CCC) algorithm in Pinnacle TPS with a dose grid of 1 × 1 × 1 mm 3 . Although there are more accurate dose algorithms 27 that can be used to reduce metal artifact and calculate dose around high‐density heterogeneities, the CCC algorithm was chosen because it is the default and also the most accurate dose algorithm used by Pinnacle and the purpose of this study was to calibrate the Pinnacle TPS to accurately calculate dose around the metallic port. The density in the TPS model of the metallic port was adjusted with an extended CT conversion table in Pinnacle until the calculation results agreed with the measurements.…”

Evaluation of New Commercially Available Metal Artifact Reduction (MAR) Algorithm on Both Image Quality and Relative Dosimetry for Patients with Hip Prosthesis or Dental Fillings

“…Our phantom study was conducted with the Catphan® 504 phantom to evaluate the impact of MAR algorithm on CT number sensitometry, geometric accuracy, The dimension of the stainless steel insert was also measured on the CT image by identifying the metal pixel using a threshold HU value (half the maximum metal HU value) [15]. An average value taken from the lateral and vertical directions of the stainless steel rod on central axis was compared to the physical dimension measured with an electronic caliper.…”

“…In addition, dual energy CT has been shown to be effective in reducing metal artifacts [11]. Some commercial products [11] [12] [13] [14] [15] have become available in the recent years due to the increasing computing power.…”

Orthopaedic and non-orthopaedic applications of a single-energy iterative metal artefact reduction technique and other metal artefact reduction techniques explained

“…The same study noted that the wide variance of tissue density in the thorax at lung, bone and soft tissue interfaces contributed to increased distant streak artefact. 19 Jeong et al 20 showed improved image quality in the context of spinal and hip joint prostheses compared with standard iterative reconstruction without IMART. Clinically, IMART has been shown to be beneficial for structure delineation and dosimetry in the planning of pelvic radiotherapy in patients with hip joint prostheses 21 and does not affect spinal stereotactic body radiation therapy treatment planning.…”