Effect of Head Position and Magnetic Resonance Sequence on Cochlear Implant-Related Artifact Size and Internal Auditory Canal Visibility.

HYPOTHESIS: To assess whether cochlear implant (CI)-related magnetic resonance imaging (MRI) artifact and visibility of the internal auditory canal (IAC) can be improved with head positioning and select MRI sequences. BACKGROUND: CI-related MRI artifact limits the use of CIs in otherwise good candidates because of the need for serial MRIs for monitoring of pathology. This most notably impacts patients with tumors of the cerebellopontine angle and IAC. METHODS: Two cadaver heads were implanted with either a Med-El CONCERT (fixed magnet) or SYNCHRONY (rotating magnet) device. Each head was imaged in a 1.5T scanner in 11 different positions. The SYNCHRONY-implanted head was also imaged in a 3.0T scanner in seven positions. Artifact size and IAC visibility (graded on a Likert scale) were measured for each head position by a neuroradiologist. RESULTS: The CONCERT CI produced significantly smaller artifact than the SYNCHRONY CI (effect size, 14.65 mm; p < 0.001). There was no significant difference between CI models in regard to IAC visibility. No head positions were statistically significantly better than neutral position for minimizing artifact size or IAC visibility, although some positions resulted in significantly larger artifact (effect sizes, 2.1-14.3 mm; p < 0.05) or significantly poorer IAC visibility (effect size, 1.4; p < 0.01). The T2 three-dimensional (CISS/FIESTA) sequence demonstrated significantly smaller artifact than T1 sequences, whereas T1 sequences demonstrated significantly better IAC visibility than T2 sequences. CONCLUSION: Head positioning and magnetic resonance sequence selection impact CI-related artifact size and IAC visibility.

Natalizumab stabilizes physical, cognitive, MRI, and OCT markers of disease activity: A prospective, non-randomized pilot study.

Natalizumab is an effective therapy for multiple sclerosis (MS). Its effectiveness has been demonstrated in several clinical and imaging studies. The objective of this study was to further demonstrate the efficacy of natalizumab using a comprehensive battery of clinical and imaging markers in the same cohort of patients followed longitudinally, hence capturing the multi-faceted nature of the MS disease process. A prospective, open-label, pilot study of 20 MS patients treated with natalizumab was conducted. High resolution MRI, Symbol-Digit Modalities Test (SDMT), and Optical Coherence Tomography (OCT) scans were obtained at baseline, 48, and 96 weeks. 15 patients completed the study. Natalizumab treatment decreased Expanded Disability Status Scale score (EDSS) and no change in SDMT, Brain Parenchymal Fraction (BPF), or any of the OCT markers of retinal degeneration was observed. Thalamic and whole brain volume as assessed by Percentage Brain Volume Change (PBVC) showed continuous deterioration. Higher baseline T2 lesion load correlated with increased rate of PBVC at 96-weeks (r = 0.566, R2 = 0.320, p = 0.035) and thalamic volume loss (r = -0.586, R2 = 0.344, p = 0.027). Most patients, 93%, achieved no evidence of disease activity (NEDA) at 2 years, likely due to early disease duration and lower initial baseline lesion load. This study further demonstrates stabilization of clinical and imaging markers of disease activity during natalizumab treatment.

Correction: Natalizumab stabilizes physical, cognitive, MRI, and OCT markers of disease activity: A prospective, non-randomized pilot study.

[This corrects the article DOI: 10.1371/journal.pone.0173299.].

Anatomic basis of the middle temporal artery periosteal rotational flap in otologic surgery.

OBJECTIVES/HYPOTHESIS: To describe the elements critical to successful middle temporal artery periosteal rotational flap harvest and utilization based on the anatomic features of the middle temporal artery. STUDY DESIGN: Description of anatomy based on cadaver dissection. METHODS: Seventy temporal fossa dissections were performed on 35 adult human cadavers. RESULTS: Sixty-nine of 70 dissections had an identifiable middle temporal artery muscular branch pedicle in the periosteum deep to the temporalis muscle. Pedicle length was at least 7 cm in 32 of 38 (84%) male cadavers and in 20 of 31 (65%) female cadavers (P = 0.054), whereas the average length required to reach the digastric ridge from the pedicle base to the digastric ridge in a mastoidectomy cavity was 5.2 cm. The pedicle sharply transitions from a posterior to a posterior-superior course 0.93 cm superior (range: 0.5-1.9 cm) and 0.04 cm posterior (range: 1.4 cm posterior-0.7 cm anterior) to the spine of Henle. Branching occurred in 26 of 69 pedicles (38%), and 20 of 31 (65%) branches were oriented posteriorly. If temporalis muscle fibers are not incorporated into the flap, the thickness is roughly three times that of a standard temporalis fascia graft. CONCLUSION: The muscular branch of the middle temporal artery is reliably identified in the periosteum deep to the posterior aspect of the temporalis muscle, and this vessel is sufficiently robust to provide axial blood supply to a rotational periosteal flap that has sufficient thickness and length to allow a variety of applications in otologic surgery. LEVEL OF EVIDENCE: NA. Laryngoscope, 126:1426-1432, 2016.