Faculty Bibliography

OBJECTIVE:Observe if metal artifact reduction (MAR) techniques applied to magnetic resonance imaging (MRI) performed on patients with cochlear implants (CI) or auditory brainstem implants (ABI) improves image quality. STUDY DESIGN/METHODS:Retrospective review. SETTING/METHODS:Tertiary care center. PATIENTS/METHODS:Patients with auditory implants who underwent clinical MRI before and after the application of MAR techniques previously described. INTERVENTIONS/METHODS:From September 2022 to March 2023, patients who underwent brain or internal auditory canal (IAC) MRI with and without MAR were identified. Sequences included T1 and T2 weighted with turbo-spin-echo (TSE) correction and fluid-attenuation inversion recovery (FLAIR). Images were analyzed for visualization of intracranial structures by two neuroradiologists. MAIN OUTCOME MEASURES/METHODS:Visibility of 14 structures graded on a four-point Likert scale. Average scores per structure and sequence were compared using paired two-tailed t-tests and change in mode score. RESULTS:Ten patients underwent pre- and post-MAR MRI. Six had a unilateral CI, three had a unilateral ABI, and one had an ABI and CI. Three patients had four devices with the internal magnet removed for both scans. All structures had significantly improved visibility on post-MAR scan except ipsilateral parietal and occipital lobes and contralateral inner ear. Mode score increased from 2 to 4 for the ipsilateral occipital lobe and from 3 to 4 for the ipsilateral semicircular canals, brainstem, and cerebellar peduncles. Significant improvement was seen in all sequences except for ipsilateral structures on T1w axial precontrast and contralateral structures on T1w coronal postcontrast. ABIs did not improve as much as CIs because they scored better on the pre-MAR scan. CONCLUSIONS:MAR techniques improve image quality for patients with MRI-compatible implants with magnets. Benefits may be more evident in CIs than ABIs.

Photon-counting CT (PCCT), approved for clinical practice for over two years now, both improves on features of conventional energy-integrating detector (EID) CT and introduces new capabilities such as multienergy acquisition. PCCT is already transforming all domains of radiology, including head and neck imaging, and will become increasingly utilized in the approaching years. In this review, we first concisely explain the key physical principles distinguishing PCCT from EID-CT. We then discuss how the underlying physics leads to the novel features associated with PCCT, focusing on improved artifact reduction, spatial resolution, contrast-to-noise ratio, as well as multienergy acquisition and reduced contrast and radiation doses. Next, we review head and neck PCCT applications and comparison to EID-CT in dental imaging, sinus imaging, temporal bone, tumor imaging, and vascular imaging. Within the temporal bone applications, we explore normal anatomy, pathologic anatomy, and the appearance of protheses and implants. Representative imaging is provided to highlight differences between PCCT and EID-CT. Finally, we highlight areas of ongoing research in PCCT.

OBJECTIVE/UNASSIGNED:To better characterize the cochlear apex in relation to surgically relevant landmarks to guide surgeons and improve procedural success of apical electrode placement. STUDY DESIGN/UNASSIGNED:Retrospective image analysis. SETTING/UNASSIGNED:Tertiary referral center. PATIENTS/UNASSIGNED:Cochlear implant recipients with available preoperative computed tomography (CT) imaging. INTERVENTION/UNASSIGNED:None. MAIN OUTCOME MEASURE/UNASSIGNED:Cochlear dimensions and cochlear apex distance measures to surgically relevant middle ear landmarks and critical structures. RESULTS/UNASSIGNED:Eighty-two temporal bone CT scans were analyzed utilizing multiplanar reformats. The average lateral width of promontory bone over the cochlear apex was 1.2 mm (standard deviation [SD], 0.3). The anteroposterior distance from the round window (avg, 4.2 mm; SD, 0.5), oval window (avg, 3.3 mm; SD, 0.3), cochleariform process (avg, 2.3; SD, 0.5), and superior-inferior distance from the cochleariform process (avg, -0.9; SD, 0.8) to the cochlear apex were measured. The relationship of the cochlear apex to critical structures was highly variable.A newly developed stapes vector was created and found to mark the posterior/superior boundary of the apex in 94% of patients. When a vector parallel to the stapes vector was drawn through the round window, it marked the anterior/inferior boundary of the cochlear apex in 89% of patients. CONCLUSIONS/UNASSIGNED:This study assists in characterizing cochlear apex anatomy and its relation to surrounding structures as a means of improving procedural accuracy and reducing trauma during apical cochleostomy. Understanding both distance relationships and expected boundaries of the apex could help to inform future surgical approaches.

OBJECTIVE:Imaging is crucial in the assessment of head and neck cancers for site, extension, and enlarged lymph nodes. Restriction spectrum imaging (RSI) is a new diffusion-weighted magnetic resonance imaging (MRI) technique that enhances the ability to differentiate aggressive cancer from low-grade or benign tumors and helps guide treatment and biopsy. Its contribution to imaging of brain and prostate tumors has been previously published. However, there are no prior studies using RSI sequence in head and neck tumors. The purpose of this study was to evaluate the feasibility of performing RSI in head and neck cancer. METHODS:An additional RSI sequence was added in the routine MRI neck protocol for 13 patients diagnosed with head and neck cancer between November 2018 and April 2019. Restriction spectrum imaging sequence was performed with b values of 0, 500, 1500, and 3000 s/mm 2 and 29 directions on 1.5T magnetic resonance scanners.Diffusion-weighted imaging (DWI) images and RSI images were compared according to their ability to detect the primary malignancy and possible metastatic lymph nodes. RESULTS:In 71% of the patients, RSI outperformed DWI in detecting the primary malignancy and possible metastatic lymph nodes, whereas in the remaining cases, the 2 were comparable. In 66% of the patients, RSI detected malignant lymph nodes that DWI/apparent diffusion coefficient failed to detect. CONCLUSIONS:This is the first study of RSI in head and neck imaging and showed its superiority over the conventional DWI sequence. Because of its ability to differentiate benign and malignant lymph nodes in some cases, the addition of RSI to routine head and neck MRI should be considered.

Brown syndrome is the inability to gaze upward beyond the horizontal level while adducting the eye due to an abnormality of the superior oblique tendon sheath complex. It is a rare extraocular muscular disorder, and its imaging is infrequently seen in radiologic practice. This article presents clinical characteristics and imaging of 5 patients with Brown syndrome and reviews the radiologic literature available, to familiarize the readers with its imaging findings.

OBJECTIVE:To determine if metal reduction magnetic resonance imaging sequences and changes in implant placement minimize artifact from cochlear implants and improve visualization of intracranial structures. STUDY DESIGN/METHODS:Cadaveric study. SETTING/METHODS:Tertiary referral center. PATIENTS/METHODS:Five cadaveric heads. INTERVENTIONS/METHODS:Specimens were implanted with Advanced Bionics HiRes Ultra3D devices at nasion-external auditory canal angles of 90, 120, and 160 degrees, and distances from the external auditory canal of 9 or 12 cm. Standard brain/internal auditory canal (IAC) sequences with metal artifact reducing technique were acquired in a 1.5T scanner. MAIN OUTCOME MEASURES/METHODS:The primary outcome was visibility of 14 intracranial structures graded on a 4-point scale (1, structures <50% visible; 2, >50% visible with some areas nonvisible from artifact; 3, artifact present but adequate for diagnosis; and 4, high quality). Scores were determined by experienced head and neck radiologists and compared with one-way analysis of variance. RESULTS:Imaging sequences included axial 5-mm whole-brain turbo spin echo (TSE) T2 with right to left and anterior to posterior encoding, fluid-attenuation inversion recovery high bandwidth, axial 5-mm whole-brain slice-encoding metal artifact correction (SEMAC), axial IAC constructive interference in steady state, and axial 3-mm T1 IAC with and without fat saturation. T1 IACs in axial and coronal planes were best for ipsilateral structures overall (mean [standard deviation {SD}], 3.8 [0.6] and 3.8 [0.5]). SEMAC (mean [SD], 3.5 [0.8]) was superior to TSE with anterior to posterior encoding (mean [SD], 3.5 [0.9) for ipsilateral cortex, cerebellopontine angle, and brainstem/cerebellum, and equivalent for the inner ear. Constructive interference in steady state and T1 with fat saturation were poor for all ipsilateral structures (mean, 2.8 [ p < 0.01]; mean, 3.1 [ p < 0.01]). The 120 degrees/12 cm position was overall best, although the 120 degrees/9 cm position still afforded visualization of ipsilateral structures; other angles and distances conferred slight advantages for specific structures of interest. CONCLUSIONS:SEMAC and T2 TSE with anterior to posterior encoding sequences provide artifact suppression while retaining excellent image quality. Different placement angles did not confer improvement in visualization, although placement distances provided slight advantages for some structures.

BACKGROUND AND PURPOSE/OBJECTIVE:-branchio-oto-renal syndrome and healthy controls. MATERIALS AND METHODS/METHODS:Temporal bone CT or MR imaging from 40 individuals with branchio-oto-renal syndrome and 40 controls was retrospectively reviewed. Cochlear offset was determined visually by 2 independent blinded readers and then quantitatively via a standardized technique yielding the cochlear turn alignment ratio. The turn alignment ratio values were compared between cochleae qualitatively assessed as "not offset" and "offset." Receiver operating characteristic analysis was used to determine the ability of the turn alignment ratio to differentiate between these populations and an optimal cutoff turn alignment ratio value. Cochlear offset and turn alignment ratio values were analyzed for each branchio-oto-renal syndrome genotype subpopulation and for controls. RESULTS:-branchio-oto-renal syndrome subset and all controls had no offset and a turn alignment ratio of >0.476. CONCLUSIONS:-branchio-oto-renal syndrome and from individuals without branchio-oto-renal syndrome or sensorineural hearing loss. The turn alignment ratio is a reliable and objective metric that can aid in the imaging evaluation of branchio-oto-renal syndrome.

Knowledge of anatomy is essential to the understanding of disease and conditions of the oral cavity and salivary glands. This article is intended to serve as an overview of the oral cavity, its subsites, and that of the neighboring salivary glands. The authors cover the anatomy of the lips, tongue, floor of mouth, hard palate, teeth, various mucosal areas, and salivary ducts. When appropriate, radiological imaging along with figures serves as a companion to highlight the clinical relevance and practical applications of specific anatomic locations.