Semiautomated MRI-Based Method for Orbital Volume and Contour Analysis.

PURPOSE: The architecture of the orbital cavity is intricate, and precise measurement of its growth is essential for managing ocular and orbital pathologies. Most methods for those measurements are by CT imaging, although MRI for soft tissue assessment is indicated in many cases, specifically pediatric patients. This study introduces a novel semiautomated MRI-based approach for depicting orbital shape and dimensions. DESIGN: A retrospective cohort study. PARTICIPANTS: Patients with at least 1 normal orbit who underwent both CT and MRI imaging at a single center from 2015 to 2023. METHODS: Orbital dimensions included volume, horizontal and vertical lengths, and depth. These were determined by manual segmentation followed by 3-dimensional image processing software. MAIN OUTCOME MEASURES: Differences in orbital measurements between MRI and CT scans. RESULTS: Thirty-one patients (mean age 47.7 ± 23.8 years, 21 [67.7%]) females, were included. The mean differences in delta values between orbital measurements on CT versus MRI were: volume 0.03 ± 2.01 ml, horizontal length 0.53 ± 2.12 mm, vertical length, 0.36 ± 2.53 mm, and depth 0.97 ± 3.90 mm. The CT and. MRI orbital measurements were strongly correlated: volume (r = 0.92, p < 0.001), horizontal length (r = 0.65, p < 0.001), vertical length (r = 0.57, p = 0.001), and depth (r = 0.46, p = 0.009). The mean values of all measurements were similar on the paired-samples t test: p = 0.9 for volume (30.86 ± 5.04 ml on CT and 30.88 ± 4.92 ml on MRI), p = 0.2 for horizontal length, p = 0.4 for vertical length, and p = 0.2 for depth. CONCLUSIONS: We present an innovative semiautomated method capable of calculating orbital volume and demonstrating orbital contour by MRI validated against the gold standard CT-based measurements. This method can serve as a valuable tool for evaluating diverse orbital processes.

Optimal Head Position Following Intratympanic Injections of Steroids, As Determined by Virtual Reality.

OBJECTIVES: To study optimal head position after intratympanic steroid injections to enhance drug bioavailability. STUDY DESIGN: Application of virtual and in vitro models of the intratympanic anatomy. SETTING: The surgical 3-dimensional printing laboratory of a tertiary academic medical center. SUBJECTS AND METHODS: A high-resolution computerized tomographic scan of healthy temporal bone and surrounding soft tissue was segmented and reconstructed to a 3-dimensional model. The tympanic membrane was perforated in the posterior-inferior quadrant. Methylene blue-stained 10-mg/mL dexamethasone was administered to the middle ear cleft, after which a 3-dimensional rotation in space was performed to hypothesize the optimal position in relation to gravity. The same stereolithography file used for the actual model was used for a digital virtual liquid flow simulation. The optimal head position was defined as the one with the maximum vertical distance between the round window membrane and the plane of the aditus ad antrum and eustachian tube orifice. RESULTS: The virtual model yielded the following position of the head as optimal: 53º rotation away from the injected ear in the vertical axis (yaw), 27º rotation toward the noninjected ear in the longitudinal axis (roll), and 10º neck extension in the transverse axis (pitch). CONCLUSIONS: Virtual imaging determined that 53º and 27º yaw and roll, respectively, away and 10º pitch were the optimal position for drug delivery after intratympanic injection to the middle ear and that an erect head position provided optimal passage of steroids from the middle ear to the inner ear.