Study of the Reliability of High Resolution CT Scan Evaluation of Eustachian Tube as Predictor of Predisposition for Chronic Otitis Media.

Eustachian tube (ET) dysfunction is one of the predisposing factors for chronic otitis media (COM). This study looks at two parameters in High Resolution Computed Tomography of temporal bone namely tubotympanic angle (TTA) and pretympanic diameter (PTD) and its relationship with COM. The objectives of the study were to compare the tubotympanic angle and pretympanic diameter of the affected ear in patients with unilateral COM with that of healthy controls, and with contralateral non-COM ear. This was a retrospective study done at a tertiary referral hospital. Database of patients who underwent high resolution CT scan of temporal bone over a period of  three and half years, was studied. The TTA and PTD of ET were measured with the help of a senior radiologist well-versed in the imaging of temporal bone. Group A consisted of 45 patients with unilateral COM, while Group B comprised 50 patients without COM. Group A was further subgrouped as A1 (COM with cholesteatoma) and A2 (COM without cholesteatoma). The TTA and PTD in COM with cholesteatoma in the affected ear were 147.98 ± 5.89° and 2.84 ± 0.82 mm respectively, and in the unaffected ear, 144.81 ± 6.43° and 3.32 ± 1.19 mm respectively. In Group A, the TTA and PTD in the affected ear of unilateral COM were 146.17 ± 6.11°, 2.97 ± 0.87 mm and in Group B, it was 143.17 ± 6.01° and 3.48 ± 0.85 mm respectively. All these were statistically significant (p value < 0.05). Increased TTA and reduced PTD of ET may be a predisposing factor for the development of COM and cholesteatoma.

Statistical asymmetry analysis of volumetric MRI and FDG PET in temporal lobe epilepsy.

PURPOSE: To analyze statistically derived threshold values of volumetric MRI and 18F fluorodeoxyglucose (FDG) PET asymmetry, independent of normative data, for non-invasive detection/exclusion of temporal lobe epilepsy (TLE). METHODS: We retrospectively analyzed amygdalohippocampal volumetry and temporal FDG PET metabolism in 33 patients (age: 29.27 ±â€¯8.56 years) who underwent surgery following Stereo-EEG implantation and had postsurgical seizure freedom lasting >12 months. The temporal lobe epilepsy group and the extratemporal lobe epilepsy (ETLE) group were compared. Percentage volume loss (PVL) was calculated from manually traced amygdalohippocampal volumetry whereas percentage metabolic loss (PML) was calculated from PET using amygdalohippocampal trace and temporal neocortical Brodmann areas (BA) template. RESULTS: Receiver operating characteristic (ROC) curve analysis identified a cutoff hippocampal PVL of 4.21% as the minimum indicating probable hippocampal involvement in seizure onset, with sensitivity of 88.89% and the specificity of 100% (p < 0.001). Region of interest (ROI)-based PML values in PET imaging showed a significant correlation with the presence of TLE in the TLE group of patients and its absence in the ETLE group of patients. Region of interest curve analysis yielded PML cutoffs of 5.77% and 8.36%, respectively, for the hippocampus and BA 38 (temporopolar neocortex) to detect TLE with the sensitivity of 72.7% and specificity of 77.8%. CONCLUSION: We describe statistical thresholds for asymmetry analysis of hippocampal volumetry and FDG PET to improve detection of TLE. These threshold parameters warrant further validation in prospective studies.

Easy and Safe Method for Facial Nerve Identification in Parotid Surgery.

Background A safe and easy anatomical landmark is proposed to identify the facial nerve in parotid surgery. The facial nerve forms the center point between the base of the styloid process and the origin of the posterior belly of the digastric muscle. Objective To evaluate the consistency, accuracy, and safety of the landmark in identifying the facial nerve. Methods The study was designed in three steps: a cadaver study, a radiologic study, and a prospective clinical study. Anatomy was initially studied in two cadavers. Then the images of 200 temporal styloid regions were studied for consistency of the presence of the styloid base. In the second part of the radiologic study, the distance between the styloid base and the origin of the posterior belly of the digastric muscle was studied in 50 parotid regions. The clinical study involved 25 patients who underwent parotidectomy. Results The styloid base was present in all the images studied. The mean distance between the styloid base and the origin of the posterior belly of the digastric was found to be 0.72 cm (range: 0.45-0.99 cm). The facial nerve could be identified consistently and safely in all patients. Conclusion This trident landmark provided safe, accurate, and easy identification of the facial nerve using two fixed bony landmarks.

Role of dual time fluorodeoxyglucose (FDG) positron emission tomography-computed tomography in identifying co-existing inflammatory and malignant disease: Who holds it (FDG) longer?

18-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) is an integral part of imaging in the follow-up of head and neck malignancies. Very often distinguishing inflammatory/infective from malignant recurrence cannot be made confidently with standard uptake value (SUV) alone, as inflammatory lesions have shown to have a very high SUV, and in some cases both can co-exist. In such doubtful cases, dual time PET-CT (3-5 h delayed) is of paramount importance in confidently differentiating inflammatory/infective from a malignant cause.