An imaging review of the hippocampus and its common pathologies.

The hippocampus is a complex structure located in the mesial temporal lobe that plays a critical role in cognitive and memory-related processes. The hippocampal formation consists of the dentate gyrus, hippocampus proper, and subiculum, and its importance in the neural circuitry makes it a key anatomic structure to evaluate in neuroimaging studies. Advancements in imaging techniques now allow detailed assessment of hippocampus internal architecture and signal features that has improved identification and characterization of hippocampal abnormalities. This review aims to summarize the neuroimaging features of the hippocampus and its common pathologies. It provides an overview of the hippocampal anatomy on magnetic resonance imaging and discusses how various imaging techniques can be used to assess the hippocampus. The review explores neuroimaging findings related to hippocampal variants (incomplete hippocampal inversion, sulcal remnant and choroidal fissure cysts), and pathologies of neoplastic (astrocytoma and glioma, ganglioglioma, dysembryoplastic neuroepithelial tumor, multinodular and vacuolating neuronal tumor, and metastasis), epileptic (mesial temporal sclerosis and focal cortical dysplasia), neurodegenerative (Alzheimer's disease, progressive primary aphasia, and frontotemporal dementia), infectious (Herpes simplex virus and limbic encephalitis), vascular (ischemic stroke, arteriovenous malformation, and cerebral cavernous malformations), and toxic-metabolic (transient global amnesia and opioid-associated amnestic syndrome) etiologies.

Efficacy of Alectinib in Patients with ALK-Positive NSCLC and Symptomatic or Large CNS Metastases.

BACKGROUND: Central nervous system (CNS) metastases represent a significant source of morbidity and mortality for patients with ALK tyrosine kinase gene (ALK)-positive NSCLC. Alectinib has demonstrated robust CNS activity in both crizotinib-naive and crizotinib-resistant settings. However, the CNS efficacy of alectinib has not been established in patients with untreated symptomatic, large CNS metastases. METHODS: In this retrospective study, patients were eligible if they had advanced ALK-positive NSCLC with large (defined as ≥1 cm) or symptomatic CNS metastases and received alectinib. Medical records and radiographic imaging were reviewed to determine treatment outcomes. CNS efficacy was assessed per the modified Response Evaluation Criteria in Solid Tumors version 1.1. RESULTS: Of the 19 patients, 15 (79%) had measurable CNS disease at baseline and were evaluable for response. The CNS objective response rate in these patients was 73.3% (95% confidence interval [CI]: 44.9%-92.2%), the CNS disease control rate was 100.0% (95% CI: 78.2%-100.0%), and the median CNS duration of response was 19.3 months (95% CI: 14.3 months-not evaluable). In 18 evaluable patients with measurable and/or nonmeasurable baseline CNS disease, the CNS objective response rate was 72.2% (95% CI: 46.5%-90.3%), the CNS disease control rate was 100.0% (95% CI: 81.5%-100.0%), and the median CNS duration of response was 17.1 months (95% CI: 14.3 months-not evaluable). All eight patients with symptoms attributable to CNS metastases had clinical improvement upon starting alectinib therapy. Six patients (32%) eventually required salvage brain radiotherapy. CONCLUSIONS: Alectinib demonstrated meaningful CNS efficacy in patients with ALK-positive NSCLC with untreated symptomatic or large brain metastases.

The Use of Magnetic Resonance Spectroscopy in the Evaluation of Pediatric Patients With Seizures.

BACKGROUND: The objective was to determine if it is useful to routinely add magnetic resonance spectroscopy (MRS) to magnetic resonance imaging (MRI) in the evaluation of seizure in the pediatric patient. Specifically, how often does MRS contribute information to conventional MRI? METHODS: A retrospective search, over a period of 3 years, of patients <18 years of age who underwent both MRI and MRS as part of the evaluation of seizures yielded a total of 233 cases in 216 patients. The medical records were reviewed to determine how many patients carried a diagnosis relevant to seizures. The MRIs and MRSs were reviewed by two neuroradiologists and an MR physicist/spectroscopist who determined by consensus in how many cases MRS contributed information regarding management, diagnosis, or prognosis, in addition to the findings on MRI alone. RESULTS: In 100 of 233 cases (43%), MRS contributed information additional to MRI. In 40 cases, MRS contributed information relevant to patient management by prompting an evaluation for an underlying inborn error of metabolism. MRS contributed information relevant to diagnosis in 24 of 100 cases (e.g., neoplasm versus dysplasia). MRS contributed information relevant to prognosis in 36 cases (e.g., hypoxic-ischemic injury). MRS added more information in cases where the patients had a diagnosis relevant to seizure before imaging. Interestingly, in 25 cases where the MRI was normal, MRS was found to be abnormal, which prompted evaluation for an inborn error of metabolism. CONCLUSIONS: These results suggest that MRS is a useful evaluation tool in addition to MRI for children undergoing imaging for the evaluation of seizures.

Odontogenic orbital inflammation: clinical and CT findings--initial observations.

PURPOSE: To retrospectively review computed tomographic (CT) and clinical findings in patients with odontogenic orbital infection. MATERIALS AND METHODS: Approval from the institutional review board was obtained for chart and scan review, and informed consent was waived for this HIPAA-compliant study. Five patients, two male and three female (median age, 37 years; age range, 13-55 years), who had odontogenic orbital cellulitis underwent clinical evaluation, CT scanning, and treatment. CT findings, including periapical lucency suggesting abscess, sinus opacification, and the route of spread of infection, were analyzed in each patient. Imaging, clinical, and surgical findings, including the initial clinical diagnosis and the presence of a periapical abscess at surgery and at pathologic examination, were compared. RESULTS: Periapical lucency and sinus opacification were seen in all patients. The route of infection spread was through either the premalar soft tissues or the maxillary sinuses. The odontogenic origin of the orbital infection was not clinically suspected in any patients. Correct diagnosis was later made at CT in all patients. Four patients had periapical abscesses at pathologic analysis, and the fifth patient had apical periodontitis at clinical analysis and granuloma at pathologic analysis. Dental surgery was required in each of the five patients for resolution of infection; four patients underwent extraction of the infected tooth, and one patient underwent incision and drainage of a periapical abscess. CONCLUSION: Abnormal periapical lucency, widening of the periodontal ligament space, and the presence of a subperiosteal abscess suggested an odontogenic origin of orbital infection.