Imaging of Altered Mental Status.

Neuroimaging is an invaluable diagnostic tool for sorting through the vast array of etiologies that underlie altered mental status (AMS). Head computed tomography (CT) without contrast is the primary modality for evaluation of AMS and should be complemented by MR imaging in cases of negative CT but high clinical concern. Studies to maximize brain imaging efficiency and improve the yield of positive scans through the utilization of clinical and laboratory pre-scan diagnostics are ongoing. However, imaging remains the gold standard due to its rapidity with which certain diagnoses can be made or excluded.

Brain MRI Features of CSF Human Immunodeficiency Virus Escape.

BACKGROUND AND PURPOSE: HIV infection of the central nervous system (CNS) is a nearly universal feature of untreated systemic HIV infection. While combination antiretroviral therapy (ART) that suppresses systemic infection usually suppresses CNS (CNS) HIV infection, exceptions have been reported with discordance between CSF and blood HIV RNA concentrations such that CSF demonstrates higher HIV concentrations than blood, referred to as CSF HIV escape. Rarely, CSF HIV escape presents with neurological symptoms, called neurosymptomatic escape. METHODS: In this report, we describe the MRI findings in 6 patients with neurosymptomatic escape who were identified at our institution. RESULTS: MR imaging suggests an encephalitis possibly evolving from a distinct HIV subpopulation within the CNS. A major difference between primary HIV infection and the current case series is that untreated HIV encephalitis usually occurs in the setting of late disease and a low CD4 whereas CSF Escape develops in setting of a higher CD4, as well as more robust immune and inflammatory responses. Our findings show a burden and distribution of white matter signal abnormalities atypical for patients adherent to ART and that differs from that seen in untreated HIV encephalitis and leukoencephalopathy. Moreover, these patients may also demonstrate perivascular enhancement, a finding not previously reported in the CSF HIV escape literature. CONCLUSION: Recognition of these imaging characteristics-patchy subcortical white matter intensities and a perivascular pattern of enhancement-may be helpful in recognition and, along with other clinical information and CSF findings, in diagnosis of neurosymptomatic escape.

Earlier and more specific detection of persistent neck disease with diffusion-weighted MRI versus subsequent PET/CT after definitive chemoradiation for oropharyngeal squamous cell carcinoma.

BACKGROUND: The purpose of this study was to test if diffusion-weighted imaging (DWI) identified persistent neck disease after chemoradiotherapy (CRT) for oropharyngeal cancer earlier and as accurately as subsequent positron emission tomography (PET)/CT. METHODS: We performed a review of patients with oropharyngeal cancer treated with definitive CRT who underwent DWI and PET/CT at a median of 8 and 14 weeks posttreatment. Imaging characteristics were correlated with pathologically proven neck failure. RESULTS: Forty-one patients and 58 hemi-necks were analyzed. With a median follow-up of 120 weeks, 4 neck failures were identified. The apparent diffusion coefficient (ADC) of lymph node failures was lower (1220 vs 1910 µm2 /s; p = .003) than non-failures. Using an ADC threshold of 1500 µm2 /s, the sensitivity, specificity, and positive and negative predictive values (PPV; NPV) were 100% (4/4), 92% (46/50), 50% (4/8), and 100% (46/46) for DWI, respectively, and 100% (3/3), 71% (22/31), 25% (3/12), and 100% (22/22) for PET/CT, respectively. CONCLUSION: Earlier DWI produced similar sensitivity and better specificity in identifying persistent neck disease as 3-month PET/CT. © 2016 Wiley Periodicals, Inc. Head Neck 39: 432-438, 2017.

The Limitations of Routine Magnetic Resonance Imaging for Long-Term Post-Treatment Locoregional Surveillance of Salivary Carcinoma.

BACKGROUND/AIMS: To determine the utility of head and neck magnetic resonance imaging (HN-MRI) for the routine surveillance of patients without concurrent symptoms or signs of recurrence more than 6 months after treatment for salivary gland carcinoma (SGC). METHODS: This is a retrospective single-institution review of SGC patients from 2000 to 2011 who underwent one or more HN-MRI scans without concurrent suspicious symptoms or signs of recurrence more than 6 months after the completion of treatment, with at least 6 months of follow-up after each scan. RESULTS: Out of an original 283 SGC patients treated surgically, 41 patients, who were disease free 6 months after treatment, had undergone 96 routine HN-MRIs without concurrent suspicious symptoms or signs. Ten out of the 41 patients (24%) experienced a false-positive finding with routine HN-MRI. None of the 96 HN-MRIs demonstrated a true-positive or false-negative finding. CONCLUSION: More than 6 months after treatment, routine HN-MRI for the detection of locoregional recurrence of SGC has a low utility in patients without concurrent suspicious symptoms or signs. While these data support the judicious use of routine HN-MRIs, the managing physician should ultimately decide on the best course of surveillance for an individual patient based on the unique risk factors and circumstances present.

The advantages and drawbacks of routine magnetic resonance imaging for long-term post-treatment locoregional surveillance of oral cavity squamous cell carcinoma.

PURPOSE: Assess the clinical utility and accuracy of routine surveillance head and neck magnetic resonance imaging (HN-MRI) for the detection of locoregional recurrence in patients with a history of oral cavity squamous cell carcinoma (OCSCC) without concurrent suspicious symptoms or signs 6 months or more after treatment. MATERIALS AND METHODS: For OCSCC patients who underwent routine (defined as: without concurrent suspicious symptoms or signs) surveillance HN-MRI at 6 months or more after treatment completion, we retrospectively determined the detection rate of locoregional disease and false positive rate. RESULTS: Out of an original cohort of 533 OCSCC patients, 46 patients, who were disease-free 6 months after treatment, had undergone 108 routine HN-MRIs from 6 to 48 months after surgery without the presence of concurrent suspicious symptoms or signs and had 6 months of subsequent follow up. 1 out of 46 (2.2%) had a true positive regional recurrence. 10 out of 46 (21.7%) patients experienced a false positive locoregional finding. CONCLUSIONS: Routine HN-MRI for locoregional surveillance of OCSCC, when used in patients without concurrent suspicious symptoms or exam findings over 6 months since treatment, may be unnecessary and costly given the very low rate of recurrence and high false positive rate. Our study supports the National Comprehensive Cancer Network guideline of limiting imaging after 6 months of primary treatment completion to patients with suspicious clinical findings. Nonetheless, managing physicians should continue to be empowered to use surveillance imaging based on risk profiles and unique circumstances for each patient.

Rosai-Dorfman Disease Isolated to the Thoracic Epidural Spine.

Rosai-Dorfman disease is a rare benign histiocytic disease that infrequently presents in the spine. We report a case of Rosai-Dorfman disease isolated to the epidural thoracic spine in a 26-year-old male. To our knowledge, this is the 15th reported case of isolated spinal disease and only the fourth case of isolated thoracic epidural disease. Given its rarity as well as non-specific symptoms and imaging findings, Rosai-Dorfman disease is often not considered and misdiagnosed on imaging studies. To help improve awareness of Rosai-Dorfman spinal disease, we review the literature and discuss the epidemiology, clinical presentation, imaging features, and treatment considerations for this condition.

Orbital and facial fractures.

This article reviews the importance of particular radiologic findings related to facial trauma and their implications for clinical and surgical management. An emphasis is placed on critical imaging signs that warrant immediate surgical attention.