Diffusion MRI of Parathyroid Adenomas using a Distortion Reduction Scheme

Objectives: To evaluate whether readout-segmented echo-planar imaging (RS-EPI) diffusion-weighted imaging (DWI) can reduce image distortion and improve the lesion identification in parathyroid adenomas (PTAs) compared to single-shot EPI (SS-EPI) DWI, and to determine whether PTAs can be differentiated from other soft tissue structures of the head and neck region by using the apparent diffusion coefficient (ADC) value. Design: Retrospective study. Setting: Kyoto University Hospital. Participants: 24 patients who underwent a magnetic resonance imaging (MRI) scan for the preoperative diagnosis of PTAs from January 2012 to March 2020 were enrolled. Main outcome measures: MRI was performed with the acquisition of a 1.5T MR imaging system (Avanto or Trio, Siemens, Erlangen, Germany) or a 3T MR imaging system (Prisma or Skyra, Siemens). Image quality and distortion of PTAs on RS-EPI and SS-EPI was evaluated using a reported five point score, and the ADC values of PTAs, thyroid glands and cervical neck lymph nodes were compared. Results: RS-EPI provided significantly less distortion but did not improve the lesion identification compared to SS-EPI. On SS-EPI, the PTAs had significantly higher ADC values compared to the cervical lymph nodes. On RS-EPI, the PTAs had significantly higher ADC values compared to the thyroid glands and cervical lymph nodes. Conclusions: RS-EPI reduces the DWI distortion in PTAs. The ADC value obtained using RS-EPI enables the differentiation of PTAs from nearby structures, such as thyroid glands and cervical lymph nodes.