Neuroradiology of infectious diseases

Abstract

Purpose of review Early diagnosis of central nervous system (CNS) infections is crucial given high morbidity and mortality. Neuroimaging in CNS infections is widely used to aid in the diagnosis, treatment and to assess the response to antibiotic and neurosurgical interventions. Recent findings The Infectious Diseases Society of America (IDSA) guidelines have clear recommendations for obtaining a computerized tomography of the head (CTH) prior to lumbar puncture (LP) in suspected meningitis. In the absence of indications for imaging or in aseptic meningitis, cranial imaging is of low utility. In contrast, cranial imaging is of utmost importance in the setting of encephalitis, bacterial meningitis, ventriculitis, bacterial brain abscess, subdural empyema, epidural abscess, neurobrucellosis, neurocysticercosis, and CNS tuberculosis that can aid clinicians with the differential diagnosis, source of infection (e.g., otitis, sinusitis), assessing complications of meningitis (e.g., hydrocephalus, venous sinus thrombosis, strokes), need for neurosurgical interventions and to monitor for the response of therapy. Novel imaging techniques such as fast imaging employing steady-state acquisition (FIESTA), susceptibility-weighted imaging (SWI), and chemical exchange saturation transfer (CEST) contrast are briefly discussed. Summary Though the radiological findings in CNS infections are vast, certain patterns along with clinical clues from history and examination often pave the way to early diagnosis. This review reiterates the importance of obtaining cranial imaging when necessary, and the various radiological presentations of commonly encountered CNS infections.

Multifocal brain abscesses caused by invasive Streptococcus intermedia: A case report

“…Combined with the patient's laboratory examination, the first consideration was inflammatory disease. Tuberculous brain abscesses and bacterial brain abscesses have similar clinical and conventional MRI findings, both manifest as ring-enhancing cystic space-occupying lesions, which require further differential diagnosis with the help of clinical manifestations, biopsy, pathology, etc (5). Combined with the patient's medical history, laboratory examination, and imaging examination, we considered that the patient had a bacterial brain abscess.…”

Critical care management of meningitis and encephalitis: an update

“…In patients with suspected bacterial meningitis, no imaging should be done before lumbar puncture in the absence of severely immunocompromised status, CNS disease history, severely altered mental status, or new-onset seizure and/or focal deficit [25,26]. In those cases, a cranial computed tomography (CT) is recommended to rule out intracranial lesions associated with a risk of cerebral herniation.…”

“…If an MRI is performed, the leptomeningeal involvement results in a purulent restriction of diffusion and/or thin and bilateral enhancement of the sulci, ventricles, or perivascular space enhancement. Postcontrast 3D T2 FLAIR is helpful in maximizing the detection of leptomeningeal enhancement [26].…”

“…MRI features of acute HSV encephalitis include bilateral, confluent, and asymmetric FLAIR white-matter hyperintensities, with cortical restriction of diffusion and often with hemorrhagic changes on T2∗ or susceptibility-weighted imaging. HSV-1 encephalitis predominates in the limbic system, unlike HSV-2, which has no specific distribution [26]. Brain MRI studies are also being increasingly used to characterize outcomes.…”

“…A diffusion sequence with smaller fields of view and thinner slices could increase sensitivity to limbic system hyperintensities [29]. Hemorrhage is uncommon [26]. 18 FDG PET-CT shows initially increased FDG uptake, then hypometabolism [30].…”