Lane, John I.

Abstract Background Evaluation of middle ear prostheses requires high-resolution imaging to assess position and structural integrity. Purpose To assess the diagnostic performance of photon-counting-detector (PCD)-CT for middle ear prosthesis imaging in cadaveric specimens. Materials and Methods Nine different middle ear prostheses were implanted in five fresh-frozen whole-head specimens, both in correct anatomic position and displaced to mimic malposition. Specimens were scanned on PCD-CT (NAEOTOM Alpha, Siemens) and energy-integrating-detector (EID)-CT (SOMATOM Force, Siemens), reconstructed at 0.2mm and 0.4mm, respectively. Eighteen cases (9 prostheses, 2 positions) per scanner were evaluated by two neuroradiologists (36 readings), blinded to scanner and position, who scored prosthesis position, reader confidence, and overall image quality. Agreement with the reference standard and between readers was compared. Results PCD-CT showed higher diagnostic confidence compared with EID-CT, while accuracy and inter-reader agreement did not demonstrate significant differences between scanners. Correct readings, PCD-CT versus EID-CT: lateral contact, 31/36 (86.1%; 95% CI: 58.3%-94.4%) vs. 29/36 (80.6%; 55.6%-91.7%), p = 0.500; medial contact, 30/36 (83.3%; 55.6%-94.4%) vs. 26/36 (72.2%; 50.0%-83.3%), p = 0.250. PCD-CT identified all cases of complete contact loss (score 3), while EID-CT missed one reading per contact. Inter-reader agreement may be higher with PCD-CT vs EID-CT (lateral: κw: 0.804 [0.578-0.941] vs. 0.571 [0.302-0.778], p = 0.250; medial: 0.684 [0.191-0.934] vs. 0.481 [0.024-0.835], p = 0.250). Reader confidence was significantly higher with PCD-CT; mean paired differences for Readers 1 and 2 were 9.4 (1.8-17.1; Holm-adjusted p = 0.019) and 23.1 points (13.4-32.7; p < 0.001) for lateral contact, and 16.4 (10.0-22.8; p < 0.001) and 17.8 points (6.8-28.8; p = 0.007) for medial contact. Readers preferred PCD-CT image quality in 16/18 (88.9%; 65.3%-98.6%) and 17/18 cases (94.4%; 72.7%-99.9%), respectively. Conclusion PCD-CT was associated with significantly higher reader confidence and preferred image quality, without significant differences in diagnostic accuracy or inter-reader agreement. These findings suggest PCD-CT is a promising modality for postoperative middle ear evaluations that warrants further investigations.

Purpose of review Photon-counting detector computed tomography (PCD-CT) represents a major technological advancement in computed tomography, offering improved spatial resolution, reduced image noise, and increased dose efficiency compared with conventional energy-integrating detector CT (EID-CT). Because many clinically relevant structures within the temporal bone are submillimeter in size, the temporal bone represents an ideal region for determining whether these technical improvements translate into meaningful clinical benefits. This review evaluates the emerging literature on PCD-CT in temporal bone imaging and examines whether higher spatial resolution meaningfully impacts clinical decision-making. Recent findings Recent studies demonstrate improved visualization of middle ear anatomy, ossicular prostheses, cochlear implant electrode arrays, and superior semicircular canal dehiscence with PCD-CT compared with conventional CT. Improved spatial resolution and reduced metal artifact have been shown to enhance assessment of prosthesis positioning, cochlear duct measurements, and differentiation of true versus near semicircular canal dehiscence. However, given the recent availability of PCD-CT, most studies to date have focused on cadaveric studies, phantom studies, or patient studies evaluating image quality rather than diagnostic accuracy or clinical outcomes. Summary PCD-CT provides substantially improved visualization of submillimeter temporal bone structures and may improve diagnostic confidence in select clinical scenarios. Nevertheless, evidence demonstrating improved clinical outcomes remains limited, and further clinical studies are needed to define the role of PCD-CT in routine temporal bone imaging.

Objective: To describe cochlear implant outcomes in a patient with bilateral rapidly progressive hearing loss secondary to Kelch-like protein–11 (KLHL11) IgG rhombencephalitis. Patient: A 26-year-old male presenting to neurotology clinic at a tertiary care center for evaluation of bilateral rapidly progressive sensorineural hearing loss, unresponsive to systemic corticosteroid therapy. Interventions: Bilateral simultaneous cochlear implantation. Main Outcome Measures: Postimplant speech testing (CNC word, AzBio sentence scoring), and changes to hearing function with fluctuations in systemic disease symptomatology. Results: Preoperative testing demonstrated poor speech perception (bilateral AzBio sentence in quiet: 43%, right-sided CNCw score: 38%, and left-sided CNCw score: 0%). Despite systemic disease progression of KLHL11-IgG rhombencephalitis, including worsening cerebellar ataxia and dysarthria, cochlear implant performance did not decrease at the time of last follow-up. At 1-year, binaural and monaural speech testing were both significantly improved compared with the 1-month testing (bilateral AzBio sentence in quiet: 91%, right-sided CNCw score: 70%, and left-sided CNCw score: 32%). Conclusions: Cochlear implantation may offer meaningful auditory rehabilitation in patients with KLHL11-IgG associated rhombencephalitis with relative auditory nerve sparing, despite ongoing disease progression. Further studies are required to evaluate the durability and generalizability of cochlear implantation across the spectrum of disease-related hearing loss.

Objective: Vestibular schwannomas (VSs) treated with stereotactic radiosurgery (SRS) often show transient loss of central tumor enhancement. We hypothesized that this loss of enhancement may correlate with better tumor control on follow-up imaging. Methods: We evaluated 198 consecutive patients from a single center who met eligibility criteria. Tumor volumes on the pre-SRS and post-SRS scans were quantified along with regions of loss of enhancement on the first post-SRS study. The latter was correlated with tumor volumes at follow-up, radiation isocenter density, and loss of serviceable hearing. Results: For the entire cohort, the median loss of enhancement on the first post-SRS scan was 14% (IQR: 6 to 25) and median rate of change in tumor volume was −4.5% per year (IQR: −10.5 to 1.5). Percent loss of central enhancement showed significant negative correlation with tumor growth not only for the entire cohort (correlation coefficient: −0.18, P =0.01), but also for the subset of patients who had available imaging until at least 2 years (n=185) and 4 years (n=179) post-SRS. Loss of enhancement also strongly correlated positively with tumor volumes and number of radiation isocenters and negatively with isocenter density. Finally, patients with greater percent loss of enhancement had an increased likelihood of progression to non-serviceable hearing, although this association was not statistically significant. Conclusions: These findings suggest that loss of central tumor enhancement in VSs post-SRS may be associated with improved tumor control.

Aberrant internal carotid arteries (ICA) are congenital vascular anomalies that occur from involution of the cervical portion of the ICA, which leads to enlargement of the normally small collateral inferior tympanic and caroticotympanic arteries. The inferior tympanic artery is a branch of the external carotid artery, usually the ascending pharyngeal artery, which extends through the inferior tympanic canaliculus (ITC), a small foramen located along the cochlea promontory. Aberrant ICAs can also be associated with a persistent stapedial artery (PSA), which is an abnormal vessel that arises from the petrous ICA and passes through the obturator foramen of the stapes. An aberrant ICA is a very important anomaly to recognize on imaging. Accurately describing its presence is important to help prevent iatrogenic injury during intervention. It is also important to distinguish an aberrant ICA from a lateralized ICA. The improvement of spatial resolution with photon counting detector (PCD)-CT has been proven to provide higher performance in detection of sub-centimeter vascular lesions compared to conventional energy-integrated detector (EID)-CT. PCD-CT also provides superior visualization of small skull-based foramina such as the inferior tympanic canaliculus, which can aid in more accurately characterizing an aberrant ICA (variant course without ITC involvement).

Introduction Although osteosarcoma represents the most common primary malignant bone tumor in children, they comprise only 0.2% of all cancers. Osteosarcoma frequently involves long bones; however, 8% of osteosarcomas involve the skull or mandible. Osteosarcoma is generally categorized based on location within the bone (central, surface, or extraskeletal) and histological grade (high-grade or low-grade). Osteoblastic osteosarcoma is a central, high-grade subtype and may be difficult to diagnose; it may present similarly to osteoblastoma, another rare, but benign, type of osteoblastic bone tumor. In this report, we present a rare case of osteoblastic osteosarcoma involving the temporal-occipital skull. Study design Case report and systematic review. Setting Tertiary referral center. Results A 21-year-old male presented for assessment of a mass appearing over his left mastoid region, first noticed within the previous 12 months. He experienced growth of the lesion and pain that increased when pressure was applied to the mass. Results from fine needle aspiration and CT-guided core biopsy were positive for osteosarcoma, osteoblastic-type. Magnetic resonance imaging of the brain and skull base revealed the mass to be 2.8 cm in maximal diameter. Given a somewhat favorable location, the tumor could be completely excised en bloc with negative margins, and the patient subsequently received adjuvant chemotherapy. The patient is doing well at last follow-up 10 months after surgery, with no evidence of recurrence to date. Conclusion The temporal bone is an uncommon location for a primary osteosarcoma, and there are numerous conditions that could present in a similar manner. This case highlights this rare occurrence of osteoblastic osteosarcoma of the temporal bone without previous exposure to radiation. There are a limited number of similar cases in the literature, and our report serves to bring awareness to this potential diagnosis and considerations related to treatment.

Objective To analyze the use of electrical field imaging (EFI) in the detection of extracochlear electrodes in cochlear implants (CI) Study Design Retrospective cohort study Setting Tertiary academic medical center Methods EFI patterns from 6 recipients with extracochlear electrodes were compared with 10 recipients with all intracochlear electrodes to identify differences in EFI patterns between these two groups. For the extracochlear group, EFI patterns were analyzed using two methods: visual inspection and calculation of the average impedance difference (AID) between specific EFI curves. These results were then compared with information from CT and plain film imaging, surgical notes, and audiology tests to confirm the placement of the electrodes in each recipient. Results An average AID of 0.06 kΩ was calculated from the EFI patterns for recipients with complete electrode insertion, whereas an average AID of 0.15 kΩ was calculated from the EFI curves measured for the extracochlear electrodes. Visual analysis of the EFI impedance curves for extracochlear electrodes showed a distinct separation from those measured for intracochlear electrodes. Based on AID analysis and visual inspection the EFI, patterns were in close agreement with the number of extracochlear electrodes detected based on either imaging, intraoperative surgical note, or audiological findings. Conclusion EFI is a noninvasive, inexpensive, and time-efficient measurement that can be used to detect extracochlear electrodes and monitor electrode migration from the cochlea.