Rajeswaran Rangasami

Case report: Antenatal MRI diagnosis of esophageal duplication cyst

Esophageal duplication cysts are classified as a subgroup of foregut duplication cysts. They are very rare and are predominantly detected in children. Antenatal detection is very rare. We report a case of an esophageal duplication cyst that was accurately identified antenatally by USG and MRI.

HRCT Correlation with Round Window Identification during Cochlear Implantation in Children

Objective: To determine the accuracy of High Resolution Computer Tomography (HRCT) temporal bone measurements in predicting the actual visualization of round window niche as viewed through posterior tympanotomy (i.e. facial recess). Materials and Methods: This is a prospective study of 37 cochlear implant candidates, aged between 1and 6 years, who were referred for HRCT temporal bone during the period December 2013 to July 2014. Cochlear implantation was done in 37 children (25 in the right ear and 12 in the left ear). The distance between the short process of incus and the round window niche and the distance between the oval window and the round window niche were measured preoperatively on sub-millimeter (0.7 mm) HRCT images. We classified the visibility of round window niche based on the surgical view (i.e. through posterior tympanotomy) during surgery into three types: 1) Type 1- fully visible, 2) Type 2- partially visible, and 3) Type 3- difficult to visualize. The preoperative HRCT measurements were used to predict the type of visualization of round window niche before surgery and correlated with the findings during surgery. Results: The mean and standard deviation for the distance between the short process of incus and the round window niche and for the distance between the oval window and the round window niche for Types 1, 2, and 3 were 8.5 ± 0.2 mm and 3.2 ± 0.2 mm, 8.0 ± 0.4 mm and 3.8 ± 0.2 mm, 7.5 ± 0.2 mm and 4.4 ± 0.2 mm respectively, and showed statistically significant difference (P < 0.01) between them. The preoperative HRCT measurements had a sensitivity and specificity of 92.3% and 96.2%, respectively, in determining the actual visualization of round window niche. Conclusion: This study shows preoperative HRCT temporal bone measurements are useful in predicting the actual visualization of round window niche as viewed through posterior tympanotomy.

Spontaneous resolution of Blake's pouch cyst.

Blakes pouch cyst is a rare posterior fossa cystic lesion characterized by posterior ballooning of the superior medullary velum into the cisterna magna. It must be differentiated from severe malformations like inferior vermian hypoplasia and Dandy Walker malformation. We describe a case in which a diagnosis of Blakes pouch cyst was made on prenatal ultrasound and later confirmed by MRI. The cyst showed complete regression on postnatal MRI.

A novel segmentation of cochlear nerve using region growing algorithm

Abstract Sensorineural hearing loss is a hearing impairment which occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain. Cochlear implants have been developed to benefit children with bilateral or unilateral Sensorineural hearing loss. A very small or absence of cochlear nerve precludes successful outcome of cochlear implant surgery. Hence, segmentation and measurement of the cochlear nerve support the surgeon’s decision to predict a normal or poor outcome of the cochlear implant. For this purpose, a modified region growing segmentation algorithm is proposed that segments the cochlear nerve region accurately. The segmentation accuracy is evaluated using parameters like Jaccard, Dice, False Positive Dice, and False Negative Dice. The segmented region is measured and evaluated using long diameter, short diameter, and cross-sectional area. The statistical analyses of intra/inter-observer correlation and limits of agreement are performed on a cross-sectional area of the cochlear nerve to investigate the reproducibility of the automated measurement.

Decubital ischemic fasciitis presenting in an unusual location

Decubital ischemic fasciitis, also called atypical decubital fibroplasia, is a distinctive fibroplasia occurring in nonambulatory older patients who are confined to bed or wheelchair-bound. These lesions are seen in the subcutaneous plane at pressure points or bony prominences. We present a case of ischemic fasciitis in a 68-year-old male patient who presented with a hard swelling in the middle third of the posterolateral aspect of the right leg, which is an unusual site for ischemic fasciitis.

Magnetic resonance imaging findings in viral encephalitis: A pictorial essay

Viral encephalitis by definition is the result of human virus affecting the brain and sparing the meninges. The other nervous system manifestations are meningitis, meningoencephalitis, encephalomyelitis, and encephalomyeloradiculitis. Encephalitis can involve any age group from children to old people. The severity of the disease depends on the viral agent and the host immune system. The patient can present with fever, headache, seizure, neurological deficit, or altered sensorium. Laboratory investigations, imaging, and cerebrospinal fluid analysis are crucial in the diagnosis of encephalitis. Magnetic resonance imaging (MRI) findings may be nonspecific or specific and plays a major role in the diagnosis of encephalitis and predicting the possible cause. This pictorial essay reviews the MRI findings of common types of viral encephalitis.

Comparison of manual and computer-assisted measurement of cochlear nerve obtained from magnetic resonance imaging

Objectives: Cochlear implantation of sensorineural hearing loss requires accurate measurement of cochlear nerve (CN). The precise measurement of very small structures can be improved by automated segmentation and measurement. The variability and reproducibility of the computer-assisted measurement were compared with manual measurements. Materials and Methods: The 3D-constructive interference in steady state magnetic resonance imaging (MRI) images of twenty patients who were referred for MRI in the assessment of giddiness/vertigo or fitness for cochlear implant during the period from June 2013 to June 2014 were analyzed. The CN sizes were measured manually by two independent radiologists. The automatic measurements were then performed on the same images, and its correlation and agreement were calculated between automated and manual measurements. Results: The intra-observer correlation coefficients were significantly larger for cross-sectional area (CSA) of CN using automated measurements when compared to manual measurement (intra-observer r: 0.94021 vs. 0.91437). Similarly, the inter-observer correlation for CSA of CN is also higher in automated measurements (inter measurement r: 0.94786 vs. 0.92013). Conclusions: Using computer-assisted CN dimension measurement, the intra- and inter-observer correlation can be improved when compared to manual measurements. The automated measurement can assist the radiologist in eliminating the need for tedious manual tracing and thus, the time and effort for manual segmentation are also significantly reduced.

Multimodality approach in evaluation of common crus aplasia

Common crus aplsia is a rare congenital anomaly caused due to abnormal reabsorption of neuroectodermal tissue of membranous common crus. Three patients came to the Department of Otorhinolaryngology with the complaints of poor response to sound. Audiometry examination revealed bilateral sensorineural hearing loss. They were referred to radiology department for high resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) temporal bone as a part of preoperative cochlear implant work up. In the present study, we discuss the HRCT and MRI findings helpful in the diagnosis of this rare anomaly in three cases.

Unenhanced renal magnetic resonance angiography in patients with chronic kidney disease & suspected renovascular hypertension: Can it affect patient management?

Background & objectives: Renal artery stenosis (RAS) is an important cause of severe hypertension in patients with chronic kidney disease (CKD). It is important to detect RAS early as it can reverse hypertension and stop rapid deterioration of renal function. The potential drawbacks of various imaging modalities used to detect RAS including contrast-related adverse effects associated with diagnostic angiography have led to increasing interest in unenhanced magnetic resonance (MR) renal angiography. The aim of this study was to detect and grade RAS in patients with CKD and suspected renovascular hypertension using unenhanced MR angiography (UMRA) and to identify patients with significant RAS (>70%) who would subsequently require further investigation and revascularization. Methods: Thirty five CKD patients with suspected RAS were subjected to UMRA using non-contrast MR angiography of ArTery and VEins 3D True fast imaging with steady state precession technique over a three year period. Patients with RAS >70 per cent on UMRA were subjected to digital subtraction angiography (DSA) with intervention if indicated. Results: In all, 76 renal arteries were evaluated using UMRA in 35 patients, of which 18 arteries showed stenosis and 11 were haemodynamically significant (eight patients). Seven patients (10 renal arteries) underwent DSA. Interpretation & conclusions: An association between UMRA and DSA findings was obtained in six patients (nine renal arteries), and these patients were stented. Post-procedure follow up showed good improvement in blood pressure and renal function. UMRA was found to be a useful non-invasive imaging modality to detect RAS in CKD patients. It can identify patients who require further invasive angiography and revascularization.

Spectrum of magnetic resonance imaging abnormalities in neonatal seizures in a tertiary care hospital in India

Background: Seizure is the most common neurological presentation during the first month of life and can lead to adverse long term outcome. The aim of the study was to describe the spectrum of brain lesions identified by magnetic resonance imaging (MRI) in term babies presenting with neonatal seizures. Methods: This retrospective descriptive study was done in a tertiary care hospital. The study subjects included term neonates presenting with neonatal seizures admitted in neonatal intensive care unit over a 5 year period, who underwent MRI brain. Data was collected from the medical records and radiology department. Results: Out of 189 neonates presenting with seizures, 155 underwent MRI brain. Brain lesions were identified in 122 (79%) babies. The most common etiological diagnosis was hypoxic ischemic encephalopathy (HIE) which was noted in 43 (28%) neonates. The other findings in the decreasing order were encephalitis in 35 (23%), metabolic disorder in 16 (10%), haemorrhage in 15 (9.7%) vascular in 12 (8%) and cortical dysplasia in 1 (