3D‐multi‐spectral T 2 mapping near metal implants

Purpose Due to host‐mediated adverse reaction to metallic debris, there is an increasing need for noninvasive assessment of the soft tissue surrounding large joint arthroplasties. Quantitative T 2 mapping can be beneficial for tissue characterization and early diagnosis of tissue pathology but current T 2 mapping techniques lack the capability to image near metal hardware. A novel multi‐spectral T 2 mapping technique is proposed to address this unmet need.Methods A T 2 mapping pulse sequence based on routinely implemented 3D multi‐spectral imaging (3D‐MSI) pulse sequences is described and demonstrated. The 3D‐MSI pulse sequence is altered to acquire images at 2 echo times. Phantom and knee experiments were performed to assess the quantitative capabilities of the sequence in comparison to a commercially available T 2 mapping sequence. The technique was demonstrated for use within a clinical protocol in 2 total hip arthroplasty (THA) cases to assess T 2 variations within the periprosthetic joint space.Results The proposed multi‐spectral T 2 mapping technique agreed, within experimental errors, with T 2 values derived from a commercially available clinical standard of care T 2 mapping sequence. The same level of agreement was observed in quantitative phantoms and in vivo experiments. In THA cases, the method was able to assess variations of T 2 within the synovial envelope immediately adjacent to implant interfaces.Conclusions The proposed 3D‐MSI T 2 mapping sequence was successfully demonstrated in assessing tissue T 2 variations near metal implants.