3D-multi-spectral T2 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 T2 mapping can be beneficial for tissue characterization and early diagnosis of tissue pathology but current T2 mapping techniques lack the capability to image near metal hardware. A novel multi-spectral T2 mapping technique is proposed to address this unmet need. METHODS: A T2 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 T2 mapping sequence. The technique was demonstrated for use within a clinical protocol in 2 total hip arthroplasty (THA) cases to assess T2 variations within the periprosthetic joint space. RESULTS: The proposed multi-spectral T2 mapping technique agreed, within experimental errors, with T2 values derived from a commercially available clinical standard of care T2 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 T2 within the synovial envelope immediately adjacent to implant interfaces. CONCLUSIONS: The proposed 3D-MSI T2 mapping sequence was successfully demonstrated in assessing tissue T2 variations near metal implants.