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The deep gray nuclei are paired interconnected gray nuclei comprising the basal ganglia and thalami. Injury to the deep gray nuclei secondary to hypoxic-ischemic injury is associated with poor short- and long-term clinical outcomes. The signal changes following hypoxic-ischemic injury are dynamic and evolve over a period of time from injury to resolution. Radiologically relevant events following hypoxic-ischemic injury include the onset of anaerobic metabolism immediately following hypoxic-ischemic injury, increase in cytotoxic edema followed by its resolution, and the onset and progression of neuronal necrosis and gliosis. Appearance of lactate peak on proton spectroscopy is the initial radiologic evidence of hypoxic-ischemic injury. Diffusion-weighted imaging has the highest prognostic value and pseudo-normalizes following 1 week of hypoxic-ischemic injury. Recommended timing for magnetic resonance imaging (MRI) is between 4 and 7 days. MR imaging performed between 1 and 6 months underestimates the extent of injury because radiologic changes are subtle. This review provides a detailed timeline of radiologic abnormalities in the deep gray nuclei following hypoxic-ischemic injury. [ABSTRACT FROM AUTHOR]

Rhino-orbito-cerebral mucormycosis is a potentially fatal disease requiring early magnetic resonance imaging (MRI) for disease evaluation and timely detection of intracranial complications. Angio-invasive nature leading to necrosis and infarction is the hallmark of mucormycosis. The disease follows a fulminant course extending from the paranasal sinuses to involve the orbit, deep neck spaces, skull base, facial bones, and intracranial compartment. Loss of vision either due to direct extension into the orbit or optic nerve infarction adds to disease morbidity. Prompt MRI using dedicated sequences can help in assessing the exact disease extent including early osseous and intracranial changes, which aid in precise disease management. [ABSTRACT FROM AUTHOR]

Background: Phase-contrast magnetic resonance imaging (PC-MRI) has been used for studying cerebrospinal fluid (CSF) dynamics in various CSF related disorders at aqueduct of Sylvius.Objective: To analyze the CSF flow dynamics qualitatively and quantitatively using PC-MRI across the aqueduct of Sylvius in diagnosed patients of tuberculous meningitis.Methods: Thirty patients, clinically diagnosed with tuberculous meningitis and mean age of 24 years (range: 12-60 years) were taken up to study the changes in CSF flow dynamics using PC-MRI with retrospective cardiac gating. Thirty age and sex matched healthy volunteers were also included for comparison and reference values. Flow quantification was done by through-plane scans acquired in the axial plane perpendicular to the aqueduct. For qualitative examination, in-plane phase contrast scans were acquired in the mid-sagittal plane. Encoding velocity was kept in craniocaudal direction. Calculated parameters were peak velocity (cm/s), average velocity (cm/s), average flow (mL/s), net forward volume (mL), and stroke volume (μL).Results: Qualitatively, loss of normal sinusoidal waveform of CSF flow was noted in two cases of hydrocephalus with exaggerated flows. Quantitatively, CSF flow parameters showed marked numerical difference in tuberculous meningitis patients with hydrocephalus on comparison with healthy volunteers and with cases without hydrocephalus.Conclusion: PC-MRI is a sensitive technique to analyze altered CSF flow dynamics in tuberculous meningitis patients. This is a useful adjunct in imaging these patients to extract both the qualitative and quantitative information about CSF flow for comprehensive evaluation. [ABSTRACT FROM AUTHOR]

Pancreatic pseudocyst is a common complication that can occur following acute or chronic pancreatitis. Commonly, they are peripancreatic in location. Rarely, they can extend to the mediastinum, and further extension to the neck is even rarer. A 55-year-old man who presented with neck stiffness and dysphagia and on imaging, was found to have a cystic lesion in the neck. Aspiration of the lesion revealed raised amylase levels suggestive of a pancreatic pseudocyst. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the role of “penumbra sign”, diffusion-weighted imaging (DWI), and the apparent diffusion coefficient (ADC) value in differentiating tubo-ovarian abscess (TOA) from ovarian malignancy. Material and methods: Thirty-six patients with 50 adnexal masses (tubo-ovarian abscess, n = 24; ovarian malignancy, n = 26), who underwent magnetic resonance imaging (MRI) with DWI, were retrospectively evaluated. “Penumbra sign” (hyperintense rim on T1W images), diffusion restriction, and mean apparent diffusion coefficient (ADC) values from cystic (c-ADC) and solid (s-ADC) components were evaluated for all the masses. Results: “Penumbra sign” on T1W images was significantly more common in the TOA group (n = 21, 87.5%) than in the ovarian malignancy group (n = 2, 7.7%) (p < 0.001). Similarly, diffusion restriction in the cystic component was more frequent in the TOA group (n = 24, 100% vs. n = 2, 10.5%; p < 0.001). In contrast, diffusion restriction in the solid component was more common in the ovarian malignancy group (n = 5, 20.8% vs. n = 26, 100%; p < 0.001). The mean c-ADC value was significantly lower in TOAs (p < 0.001). A c-ADC value of 1.31 × 10-3 mm2/s may be an optimal cut-off in distinguishing TOAs from ovarian malignancies. Conversely, the mean s-ADC value was significantly lower in the ovarian malignancy group (p < 0.001). An s-ADC value of 0.869 × 10-3 mm2/s may be an optimal cut-off in differentiating ovarian malignancies from TOAs (p < 0.001). ROC curve analysis showed that c-ADC values had a higher diagnostic accuracy than s-ADC values. Conclusions: “Penumbra sign” on T1W images, diffusion characteristics, and ADC values provide important clues in addition to conventional MR imaging features in differentiating TOA from ovarian malignancy. [ABSTRACT FROM AUTHOR]

There are very limited reports of aplasia of bilateral submandibular glands. We report the case of a 55-year-old male who presented with nontender palpable sublingual masses. On computed tomography and magnetic resonance imaging, bilateral submandibular gland aplasia and compensatory hypertrophy of bilateral parotid and sublingual glands were seen with herniation of hypertrophied sublingual glands through the bilateral mylohyoid muscles presenting as palpable sublingual region masses. Additional finding of bilateral accessory parotid glands was also noted. Prolapsed hypertrophied sublingual glands should be considered in patients presenting with bilateral sublingual masses to avoid unnecessary invasive procedures. We suggest radiological evaluation of such cases prior to any intervention. [ABSTRACT FROM AUTHOR]

Brain tumors are the second most common malignancy and the most common solid tumors in the pediatric population. Most brain tumors in the pediatric population are primary in origin contrary to the adult population. The various factors useful for establishing the diagnosis include the age of the patient, imaging characteristics, and location of the tumor. Infratentorial tumors are more common between 4 and 10 years of age, whereas supratentorial tumors are common in neonates and infants up to 3 years. Conventional computed tomography and magnetic resonance imaging are of paramount importance in the diagnostic evaluation of these tumors which help in their characterization and allow accurate assessment of their extent. The updated World Health Organization classification of brain tumors has incorporated various genetic and molecular parameters. It is essential for the radiologists to be familiar with the imaging features of genetic tumor subtypes as it plays a role in patient management and prognostication. Advanced neuroimaging provides additional information regarding the metabolism and physiology of these lesions, thereby aiding in their diagnosis and follow-up. [ABSTRACT FROM AUTHOR]

Objective: To describe the spectrum of magnetic resonance imaging (MRI) findings in patients with neurological manifestations of dengue. Materials and Methods: We included nine patients with dengue fever (three females and six males; age range, 9-30 years), all of whom presented with neurological manifestations. The MRI examinations, performed in 1.5 T or 3 T scanners, included T1- weighted, T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences. Diffusion-weighted imaging with apparent diffusion coefficient mapping was also employed. Fast low-angle shot and susceptibility-weighted gradient-recalled echo sequences, as well as contrast-enhanced T1-weighted scans, were also obtained in order to assess parenchymal enhancement. MRI scans were analyzed for lesion distribution and imaging features. Results: All patients showed areas of altered signal intensity that appeared as hyperintensity on T2-weighted and FLAIR sequences. The most commonly affected site was the basal ganglia-thalamus complex. Other affected sites were the cerebellum, cerebral cortex, white matter and brainstem. In all cases, we observed patchy areas of restricted diffusion and focal areas of hemorrhage. Conclusion: Dengue encephalitis commonly affects the basal ganglia, thalamus, cerebellum, cerebral cortex and white matter. Therefore, MRI should be an indispensable part of the evaluation of patients with neurological complications of dengue fever. [ABSTRACT FROM AUTHOR]