The Otology Group of Vanderbilt, Vanderbilt University Medical Center, Nashville, TN, USA.
Vanderbilt University School of Medicine, Nashville, TN, USA.
Ann Otol Rhinol Laryngol. 2023 Mar;132(3):250-258. doi: 10.1177/00034894221089143. Epub 2022 Apr 5.
To evaluate cochlear implant (CI) magnet-related MRI artifact shape and size, as well as imaging indications and clinical adequacy of scans.
A retrospective chart review was performed for patients undergoing CI and subsequent MRI head imaging from 2014 to 2020 at a single institution. Indications and adequacy of each scan was recorded, and interpretability compared by indication. Magnet-related artifact size was determined by performing ellipsoid modeling at axial slice of greatest signal loss. Artifact radius in centimeters was calculated for 5 sequence categories, and size compared between sequences, manufacturers, and by time from implantation.
Twenty patients underwent 58 head MRI scans. Approximately 76% of MRIs (n = 44) for 70% of patients (n = 14) were performed for indications known of prior to implantation; the remainder were performed during workup of new issues. Desired structures were interpretable in 23 (52%) of known-indication MRIs and 8 (57%) of new-indication MRIs, without significant difference ( = .751). Magnet-related artifact magnitude, compared to the reference T1-weighted fast spin echo (FSE) (4.47 cm), was similar in T2 FSE (4.57 cm, = .068) and T1 gradient echo (GRE) sequences (4.79 cm, = .28), but significantly greater in T2 GRE (6.86, < .0001) and DWI (7.56 cm, < .0001) sequences.
DWI and T2 GRE sequences are less useful in MRI evaluation of CI patients. With a more favorable artifact profile, T1 FSE, T2 FSE, and T1 GRE sequences more likely yield clinically useful information. The large proportion of scans performed for known pathology represents an opportunity to optimize for magnet location preoperatively.
评估人工耳蜗（CI）磁铁相关的 MRI 伪影的形状和大小，以及扫描的成像适应证和临床充分性。
对 2014 年至 2020 年在一家机构接受 CI 并随后进行头部 MRI 成像的患者进行回顾性图表审查。记录了每次扫描的适应证和充分性，并根据适应证比较了可解读性。通过在信号损失最大的轴位切片上进行椭球建模来确定磁铁相关伪影的大小。对于 5 种序列类别，计算了伪影半径（以厘米为单位），并比较了不同序列、制造商和植入后时间的大小。
20 名患者进行了 58 次头部 MRI 扫描。大约 76%（n=44）的 MRI 是为 70%（n=14）的患者进行的，这些患者的适应证是在植入前已知的；其余的是在新问题的检查过程中进行的。在已知适应证的 23 次 MRI（52%）和新适应证的 8 次 MRI（57%）中，可解读的目标结构无显著差异（ = .751）。与参考 T1 加权快速自旋回波（FSE）（4.47cm）相比，T2 FSE（4.57cm， = .068）和 T1 梯度回波（GRE）序列的磁铁相关伪影大小相似，但 T2 GRE（6.86cm， < .0001）和 DWI（7.56cm， < .0001）序列的伪影显著更大。
DWI 和 T2 GRE 序列在 CI 患者的 MRI 评估中用处不大。T1 FSE、T2 FSE 和 T1 GRE 序列具有更好的伪影特征，更有可能产生有临床意义的信息。对于已知病变进行大量扫描代表了在术前优化磁铁位置的机会。
