The role of magnetic resonance imaging and magnetic resonance sialography in the evaluation of salivary sialolithiasis: radiologic-endoscopic correlation.

Purpose: To evaluate the role of magnetic resonance imaging (MRI) and MR sialography in salivary gland calculi in correlation with sialendoscopy. Material and methods: In this prospective study, pre-therapeutic MRI was performed for patients with clinically suspected sialolithiasis. In addition, sialendoscopy with or without surgery was performed. The detectability, number, size, and location of calculi (distance of obstruction from the ostium and masseter line) and the condition of the main duct at MRI were reported. Agreement between the 2 readers was confirmed for all MRI findings. Data regarding the detectability, number, and size of calculi were correlated with endoscopy. Results: There was excellent agreement between the 2 readers regarding the detection and number of calculi at MR sialography (κ = 1, p < 0.001). As regards MRI measurements, excellent interclass correlation was found between the 2 readers regarding size of calculi, distance of calculi from the ostium, and distance from the masseter line (κ = 0.98, 0.98, 0.97, respectively; p < 0.001). In correlation with sialendoscopy, MRI was false negative in 1 patient, and it missed 1 calculus in 3 patients with multiple calculi. There was no statistically significant difference between the size of calculi detected by MRI and true size of calculi retrieved by sialendoscopy. Conclusion: MR sialography is an accurate modality for diagnosis of the presence, size, and location of sialolithiasis and offers accurate ductal mapping for sialendoscopists.

Role of MR Imaging in Head and Neck Squamous Cell Carcinoma.

Routine and advanced MR imaging sequences are used for locoregional spread, nodal, and distant staging of head and neck squamous cell carcinoma, aids treatment planning, predicts treatment response, differentiates recurrence for postradiation changes, and monitors patients after chemoradiotherapy.

Atypical intracranial aneurysms: spectrum of imaging findings in computed tomography and magnetic resonance imaging.

We aim to describe demographics, clinical presentation, and spectrum of CT and MRI features suggestive of atypical intracranial aneurysms. The imaging protocols used for the diagnosis of intracranial aneurysms were thoroughly reviewed, including different CT and MRI protocols. We classified atypical aneurysms according to their location, size, clinical presentation, and specific imaging features. Dissecting aneurysms are one of the causes of stroke in young adults that may show intimal flap and double lumen. Traumatic intracranial aneurysms are a rare but serious complication of head injuries. Mycotic aneurysms are small and multiple at distal branch points with a high risk of rupture. Aneurysms with vasculitis are fusiform with a wide neck at a non-branch point that may be associated with vessel wall enhancement. Atherosclerotic aneurysms are usually large fusiform that affect large arteries. Oncotic aneurysms are relatively rare. They were reported to occur in patients with left atrial myxoma. Our study represented a wide spectrum of atypical intracranial aneurysms with their detailed diagnostic imaging findings on MRI and CT including newly introduced MRI sequences, which greatly influenced early diagnosis and timely management.

Role of dynamic sleep MRI in obstructive sleep apnea syndrome.

PURPOSE: To identify obstruction sites of the upper airway during sleep in patients with obstructive sleep apnea syndrome (OSAS) under dynamic conditions and improve knowledge to guide surgical treatment and advancements. MATERIALS AND METHODS: The study included 15 patients (5 females and 10 males) who were diagnosed as having OSAS. Overall mean age was 40.2 years (± 7.01 years). All the patients underwent drug-induced sleep endoscopy (DISE) and dynamic sleep MRI. The presence, location, and direction of airway collapse were assessed. Dynamic MRI findings were correlated to DISE. Data of the site and direction of airway collapse were correlated with those of endoscopic findings and interobserver agreement was done. RESULTS: The dynamic images in sagittal section showed collapse of the upper airway at retropalatal level in 14 patients (93.33%) and at retroglossal level in seven patients (46.7%) and of these 14 patients; seven had combined retropalatal and retroglossal collapse. These findings were highly correlated with DISE findings with an excellent interobserver agreement for retropalatal and retroglossal levels (Kappa = 1 and 0.867, P value = 0.000), respectively. Objective measurements of the direction of collapse in axial dynamic sleep MRI images showed significant statistical correlation with endoscopic findings regarding retropalatal anteroposterior and circumferential collapse (Kappa = 0.58 and 0.52, P value = 0.02 and 0.03, respectively). CONCLUSION: Dynamic sleep MRI can reliably characterize the actual site of dynamic airway obstruction and has the potential of improving predictions of successful surgical outcomes in OSAS patients.

Peripheral Nerve Sheath Tumors of Head and Neck: Imaging-Based Review of World Health Organization Classification.

We aim to review the imaging appearance of peripheral nerve sheath tumors (PNSTs) of head and neck according to updated fourth edition of World Health Organization classification. Peripheral nerve sheath tumor can be sporadic or associated with neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis. Schwannoma is the most common benign PNST that can be intracranial or extracranial and appears heterogeneous reflecting its histologic composition. Melanotic schwannoma is a different entity with high prediction of malignancy; it shows hypointense signal on T2-weighted image. Neurofibroma can present by localized, plexiform, or diffuse lesion. It usually appears homogeneous or shows a characteristic target sign. Perineurioma can be intraneural seen with the nerve fiber or extraneural appearing as a mass. Solitary circumscribed neuroma and neurothekeoma commonly present as dermal lesions. Nerve sheath myxoma may exhibit high signal on T1 weighted image. Benign triton tumors can be central, aggressive lesion, or peripheral nonaggressive lesion. Granular cell tumor shows hypointense signal on T2 weighted image. Neuroglial heterotopia most commonly occurs in the nasal cavity. Ectopic meningioma arises from ectopic arachnoid cells in the neck. In hybrid PNST, combined histological features of benign PNST occur in the same lesion. Malignant PNSTs are rare with an aggressive pattern. Computed tomography and magnetic resonance imaging are complementary studies to determine the location and extent of the tumor. Advanced magnetic resonance sequences, namely, diffusion-weighted imaging and dynamic contrast enhancement, can help in differentiation of benign from malignant PNST.

Role of Fused Three-Dimensional Time-of-Flight Magnetic Resonance Angiography and 3-Dimensional T2-Weighted Imaging Sequences in Neurovascular Compression.

BACKGROUND: To evaluate role of fused 3-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) and 3-dimensional constructive interference in steady state (3D-CISS) in neurovascular compression in trigeminal neuralgia (TN) and hemifacial spasm (HFS). MATERIAL AND METHODS: A prospective study was conducted on 30 patients (mean age 47.20 ± 11.69 years), 17 (56.7%) male and 13 (43.3%) female, with TN and HFS. 3D-TOF-MRA and 3D-CISS sequences of the cerebellopontine angle were performed, as well as postprocessing with fusion of the images. Two independent readers assessed the degree of neurovascular conflict. The images were evaluated for site, signal, and degree of nerve compression and the offending vessel. The kappa test for interobserver agreement was done. RESULTS: The interobserver agreement of both readers was excellent for degree of compression (k = 0.70, 95% confidence interval [CI] 0.49-0.92, r = 0.856, P = 0.001), excellent for the side affected (k = 1.0, 95% CI = 1.0-1.0, r = 1.000, P = 0.001), excellent for the offending vessel (k = 0.85, 95% CI = 0.66-1.0, P = < 0.001), and excellent for the position of the offending vessel (k = 0.685, 95% CI = 0.489-0.882, r = 0.863, P ≤ 0.001). There was no significant correlation between the degree of compression and signal intensity. CONCLUSIONS: Fused 3D-TOF-MRA and 3D-CISS images are a reliable, noninvasive tool for the evaluation of offending vessel and degree of affection in patients with neurovascular compression. MRA-CISS can be used for evaluation and treatment planning of neurovascular compression in TN and HFS.

Imaging of Brain Infarctions: Beyond the Usual Territories.

In this review, our intension is to present imaging features of several categories of uncommon cases of brain infarctions including infarctions associated with neurovascular variants, infarctions along small arterial territories, and brainstem stroke syndromes. Infarctions associated with neurovascular variants include azygos anterior cerebral artery territory infarction and artery of Percheron infarction. In the second group, we discuss anterior choroidal artery infarction and artery of Heubner infarction. The third group highlights brainstem stroke syndromes, including Claude and Benedikt syndromes due to midbrain infarction; Foville, Marie Foix, and locked-in syndromes due to pontine infarction; and Dejerine (medial medullary), bilateral medial medullary, and Wallenberg (lateral medullary) syndromes.

Assessment of Mass Effect Sign at High-Resolution Computed Tomography in Prediction of Cholesteatoma.

OBJECTIVE: The aim of this study was to assess the accuracy of mass effect sign in the diagnosis of cholesteatoma at high-resolution computed tomography (HRCT). METHODS: This prospective study included 32 ears in 24 patients with chronic otitis media who underwent HRCT of the temporal bone. Otoscopic and operative notes were recorded. Image analysis was done both qualitatively and quantitatively. In the qualitative analysis, mass effect was evaluated visually by comparing both ears together in 4 certain anatomical sites. Ossicular erosions, erosion of tegmen tympani, erosion of tympanic segment of facial nerve canal, and the presence of lobulated nondependent opacity were also evaluated. In the quantitative analysis, we calculated the difference between the distances of the described anatomical sites in both ears. RESULTS: Qualitative analysis of mass effect sign showed 97.1% accuracy in detecting cholesteatoma. Ossicular erosions showed 69.2% accuracy in the diagnosis of cholesteatoma. In the quantitative analysis, we found that the cutoff point of 0.45 mm in the difference of aditus measure between both ears showed 85.3% accuracy in differentiating cholesteatoma from otitis media. The cutoff point of 0.75 mm in the differences in supratubal measure showed 86.1% accuracy. The cutoff point of 0.45 mm in the medial to incus measure showed 100% accuracy. CONCLUSION: High-resolution computed tomography is highly valuable for the detection of mass effect sign, which has great importance in diagnosing cholesteatoma.

The misplaced cochlear implant electrode array.

OBJECTIVES/HYPOTHESIS: Evaluation of the clinical, electrophysiologic findings, the management plans of the misplaced cochlear implant electrode array and the possible causes of misplacement. Also to provide recommendations to prevent a repeat of cochlear implant electrode misplacement into abnormal sites. STUDY DESIGN: Retrospective study. METHODS: Pediatric cochlear implant recipients implanted from January 2012 till January 2018 whose electrode arrays were misplaced outside the cochlea into the surrounding structures. RESULTS: Eight pediatric cochlear implant recipients, were identified to have a misplaced cochlear implant electrode array. Different sites of improper placement included one case in the eustachian tube, another one in the vestibule, one electrode array was found to be in the petrous apex lateral to the internal carotid canal, and another one in the internal auditory canal (IAC), and in three cases the electrode arrays were packed in the hypotympanum, and lastly an electrode array recoiled after perfect insertion and was found to be in the facial recess. Six cases were initially identified immediate because of their poor intraoperative implant testing which prompted imaging while in two cases, the one found in the petrous apex and the other one in the internal auditory canal (IAC) were diagnosed several months after surgery due to unsatisfactory auditory skills development or absent behavioral responses following implantation. CONCLUSIONS: Electrode array misplacement may be due to either failure to identify the anatomical landmarks during surgery specially the infracochlear air cell track or unidentified inner ear malformation. The routine use of intraoperative electrophysiologic testing and postoperative imaging should help to avoid such complications. Misplacement is a rare but still correctable complication after cochlear implant surgery. The diagnosis of misplacement can be delayed for years and in this occasion, it is suspected when benefit from the implant is limited or absent. Once misplacement is diagnosed revision surgery has to be done.