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.

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.