MRI Findings of Acute Hippocampal Disorders: Pictorial Essay.

The hippocampus is one of the most metabolically active regions of the brain; therefore, it may be affected by various acute disorders. This study aimed to introduce and categorize various acute conditions that can involve the hippocampus and explain the findings of MRI, especially diffusion-weighted imaging (DWI). Acute hippocampal disorders are divided into six categories: infection, inflammation, metabolic, ischemic, traumatic, and miscellaneous. In this study, patients were retrospectively reviewed based on clinical findings and MRI, especially DWI. All diseases had been confirmed clinically or pathologically. Many acute hippocampal disorders overlap with the clinical manifestations. Thus, it is necessary to categorize acute hippocampal lesions and understand their specific imaging findings for differential diagnosis.

Imaging characteristics of slow-growing soft tissue chondroma of the tongue: A case report.

INTRODUCTION: Extraskeletal soft tissue chondroma (STC) is a rare benign tumor. Soft-tissue chondromas rarely occur in the oral cavity. In this study, we aimed to confirm a slow-growing tongue mass using magnetic resonance imaging. PATIENT CONCERNS: A 60-year-old woman presented with a painful, slow-growing tongue mass that had persisted for 17 years. Intraoral examination revealed a pedunculated mass covered with mucosa on the right side of her tongue. DIAGNOSIS: CT and MRI revealed a lobulated heterogeneously enhancing mass without calcification. Compared with previous images obtained 17 years prior, the mass presented slow growth, more prominent enhancement, and lobulated contour. Histopathological examination confirmed the presence of STC. INTERVENTIONS: Excision of the mass surrounding normal tissue was performed under general anesthesia. OUTCOMES: During 1-year follow-up period, no recurrence was observed. CONCLUSIONS: In this study, STC lesions were slow-growing, and changed from weakly homogeneous enhancement and clean margins to markedly heterogeneous enhancement and lobulated margins over time.

Erratum: Acute Acquired Metabolic Encephalopathy Based on Diffusion MRI.

This corrects the article on p. 2034 in vol. 22, PMID: 34564957.

Acute Acquired Metabolic Encephalopathy Based on Diffusion MRI.

Metabolic encephalopathy is a critical condition that can be challenging to diagnose. Imaging provides early clues to confirm clinical suspicions and plays an important role in the diagnosis, assessment of the response to therapy, and prognosis prediction. Diffusion-weighted imaging is a sensitive technique used to evaluate metabolic encephalopathy at an early stage. Metabolic encephalopathies often involve the deep regions of the gray matter because they have high energy requirements and are susceptible to metabolic disturbances. Understanding the imaging patterns of various metabolic encephalopathies can help narrow the differential diagnosis and improve the prognosis of patients by initiating proper treatment regimen early.

Fulminant Disseminating Fatal Granulomatous Amebic Encephalitis: The First Case Report in an Immunocompetent Patient in South Korea.

Central nervous system infections caused by free-living amoeba are very rare, but often fatal. The typical image findings of amebic meningoencephalitis are non-specific, showing ring-like enhancement. We report the first case of fulminant disseminating fatal granulomatous amebic encephalitis caused by Balamuthia mandrillaris in an immunocompetent patient in South Korea. Our case exhibited two interesting features: one was the unusual clinical course and the other was additional image findings. Magnetic resonance imaging revealed a rim-enhancing lesion with intralesional blooming dark signal intensity on susceptibility weighted imaging and low signal intensity on diffusion weighted images and on apparent diffusion coefficient maps. Differential diagnosis was started from a tumor or non-tumorous lesion, and diagnosis was difficult due to the rarity of the disease. Following the clinical and diagnostic courses of our case, we recommend inspecting image findings of granulomatous amebic encephalitis for early diagnosis.

Susceptibility-Weighted Imaging as a Distinctive Imaging Technique for Providing Complementary Information for Precise Diagnosis of Neurologic Disorder.

Various sequences have been developed for MRI to aid in the radiologic diagnosis. Among the various MR sequences, susceptibility-weighted imaging (SWI) is a high-spatial-resolution, three-dimensional gradient-echo MR sequence, which is very sensitive in detecting deoxyhemoglobin, ferritin, hemosiderin, and bone minerals through local magnetic field distortion. In this regard, SWI has been used for the diagnosis and treatment of various neurologic disorders, and the improved image quality has enabled to acquire more useful information for radiologists. Here, we explain the principle of various signals on SWI arising in neurological disorders and provide a retrospective review of many cases of clinically or pathologically proven disease or components with distinctive imaging features of various neurological diseases. Additionally, we outline a short and condensed overview of principles of SWI in relation to neurological disorders and describe various cases with characteristic imaging features on SWI. There are many different types diseases involving the brain parenchyma, and they have distinct SWI features. SWI is an effective imaging tool that provides complementary information for the diagnosis of various diseases.

A Case of Isolated Nodular Infarction Mimicking Vestibular Neuritis on the Contralateral Side.

Differentiating central vestibulopathy from more common vestibular disorders is crucial because it often necessitates different treatment strategies, and early detection can help to minimize potential complications. Isolated nodular infarct is one of the central brain lesions that can mimic peripheral vertigo. We present a case of isolated nodular infarct that had been misdiagnosed as vestibular neuritis on the contralateral side at the initial evaluation. The patient was successfully treated with anticoagulants and antihyperlipidemic agents. Clinicians should keep in mind that some causes of central vertigo mimic peripheral vestibulopathy at the early stage.

Lymphoplasmacyte-Rich Meningioma With Atypical Angiomatous Feature and an Increased Deposition of IgG4-Positive Plasma Cells: An Unusual Case Report.

Lymphoplasmacyte-rich meningioma (LPRM) is an extremely rare variant of meningioma, and a small percentage of LPRM may be associated with IgG4-related disease. To date, the coexistence of 2 rare meningioma variants consisting of LPRM and angiomatous meningioma within one neoplasm has not been reported in the literature. A 56-year-old woman presented with episodes of frequent and severe epistaxis that began 4 months ago. Initial magnetic resonance imaging showed localized, heterogeneous, and intermediate to high signal lesion at the odontoid process and clivus. In subsequent magnetic resonance images, the mass grew to the posterior nasopharyngeal wall, and compression to the medulla, and a suspicious enhancement of both distal vertebral arteries became evident even though there was 3 times of partial resection over 17 years. The tumor showed regional and temporal heterogeneity, and atypical features such as mitoses and a high proliferative index were also identified in the area of angiomatous meningioma in addition to LPRM with an increased deposition of IgG4-positive plasma cells within the neoplasm.

Magnetic resonance imaging predicts chronic dizziness after benign paroxysmal positional vertigo.

OBJECTIVES: We aimed to evaluate the clinical implications of magnetic resonance imaging (MRI) findings in patients with benign paroxysmal positional vertigo (BPPV). METHODS: A total of 120 patients diagnosed with BPPV completed MRI at the emergency room between December 2012 and June 2015 and met our criteria for inclusion in this study. Epidemiologic characteristics, the results of audio-vestibular testing, and MRI findings were retrospectively analyzed. RESULTS: The most common findings were white matter hyperintensities (70.0%), sinusitis (34.2%), and brain atrophy (25.0%). There were no significant differences in MRI findings or epidemiologic characteristics according to BPPV subtype (p>0.05). A multiple regression analysis revealed that BPPV recurrence (odds ratio, 6.88; 95% confidence interval, 1.67-34.48; p=0.009) and brain atrophy (odds ratio, 4.39; 95% confidence interval, 1.11-21.28; p=0.036) were positively associated with dizziness lasting longer than 3months. CONCLUSION: Brain atrophy was independently associated with long-lasting dizziness after BPPV. Although the mechanism is unclear, brain atrophy may have relevance to otoneurotologic disease-related changes in brain structure.

Can clinical and MRI findings predict the prognosis of variant and classical type of posterior reversible encephalopathy syndrome (PRES)?

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is characterized by clinical symptoms that are associated with bilateral and symmetric vasogenic edema in the parietal and occipital lobes. However, this is rarely present with predominant involvement of the brain stem and cerebellum (variant). PURPOSE: To evaluate which clinical or magnetic resonance imaging (MRI) findings can help to predict the prognosis of variant and classical type of PRES and whether or not there is difference between two types of PRES. MATERIAL AND METHODS: We retrospectively evaluated MRI and clinical findings from 49 patients with PRES. These patients were divided into two groups. In group I, patients had atypical distribution of lesions. In group II, patients had typical distribution of lesions. Follow-up MRI was performed on 26 patients. We assessed the MRI features, clinical data, and the patients' outcomes. RESULTS: The mean blood pressure (BP) was significantly higher in group I (195.52/121.09 mmHg and 156.78/99.53 mmHg for groups I and II, respectively). The other factors assessed were not significantly different between the two groups. Lesions in 24 of 26 patients reversed upon follow-up. Sequelae were observed in 11 patients (group I, 7; group II, 4). However, there were no significant differences between the two groups. Except for those patients who died, seven of the nine patients with sequelae upon follow-up imaging had hemorrhage or irreversibility of lesions. CONCLUSION: Even though BP influences the involvement of the brain stem, involvement of the brain stem is not influential on the prognosis. It seems that the influential factor to prognosis is the reversibility of lesions and hemorrhage.

Brain functions associated with verbal working memory tasks among young males with alcohol use disorders.

This study aimed to investigate the differences in brain functions during verbal working memory between individuals with alcohol use disorders (AUD) and normal controls. fMRI was used to scan brain activations associated with verbal working memory while participants performed 2-back and 0-back tasks. A total of 21 young male college students participated in the study. Eleven of those who clinically met the criteria for AUD were assigned to the AUD group, whereas ten demographically similar subjects who were social drinkers but not AUD were assigned to the normal control group. The AUD group showed less activation in bilateral frontal and precentral, left superior temporal, left superior parietal, and left cerebellar cortex during the 2-back task relative to 0-back task compared to the normal control group. In contrast, the control group showed less activation only in the right uncus than the AUD group. These results suggest that subjects with AUD present abnormality in brain functioning during verbal working memory.

Image presentation. The nipple-areolar complex: a pictorial review of common and uncommon conditions.

OBJECTIVE: The purpose of this presentation is to show the radiologic findings of normal variants and benign and malignant diseases that affect the nipple-areolar complex. METHODS: We evaluated the imaging findings of nipple-areolar complex lesions, using multiple breast imaging modalities including mammography, sonography, galactography, contrast-enhanced magnetic resonance imaging (MRI), and positron emission tomography/computed tomography. RESULTS: Radiologic features of nipple-areolar complex lesions, including Montgomery tubercles, nipple inversion, benign calcifications, inflammation, duct dilatations, intraductal papillomas, fibroadenomas, neurofibromatosis, dermatosis of the nipple, and breast malignancy, have been illustrated. CONCLUSIONS: A clinical examination is essential and an appropriate imaging evaluation with multiple modalities is often necessary to accurately diagnose an underlying abnormality of the nipple-areolar complex. Given the limitations of conventional mammography, supplemental mammographic views often are needed, and sonography may be performed to further characterize a mammographic or clinical finding. Also, contrast-enhanced MRI may be useful for additional evaluation.

Fibrosing inflammatory pseudotumor of the nasopharynx: MR features and histopathologic correlation.

PURPOSE: To describe the magnetic resonance (MR) imaging features of six cases of pathologically proven fibrosing inflammatory pseudotumor involving the nasopharynx, and to compare the MR signal intensities of the lesions with histopathologic findings. METHODS: We reviewed the MR finding of six patients with pathologically proved fibrosing inflammatory pseudotumor at the nasopharyngeal wall with respect to the following points: extent, margins, signal intensity and enhancement degree of the lesion; cervical lymphadenopathy and response to steroid therapy. MR findings were correlated with histopathologic findings. RESULTS: All lesions showed ill-defined margins and looked less-likely contour bulging features. The signal intensity of the lesions was hypointense or slightly heterogeneous relative to brain cortex on both T1- and T2-weighted images, and enhancement was weakly homogeneous in all cases. There was no demonstrable cervical lymphadenopathy in all cases. After steroid therapy, the lesions showed decreased extent and weaker enhancement in three patients. Histopathologic findings showed high degree of polymorphous inflammatory cellular infiltration with underlying significant reactive fibrosis. CONCLUSION: Fibrotic inflammatory pseudotumors involving nasopharynx are very rare, and can mimic malignancy. MR imaging showed ill-defined margins, hypointensity or slightly heterogenous signal intensity on T2-weighted image and weak enhancement. There was no significant cervical lymphadenopathy.

Reconstructive endovascular treatment of ruptured blood blister-like aneurysms of the internal carotid artery.

OBJECT: Ruptured blood blister-like aneurysms (BBAs) of the internal carotid artery (ICA) are rare but carry a high rate of morbidity and mortality. Furthermore, BBAs are very difficult to treat surgically as well as endovascularly. The authors present their experience in treating BBAs with reconstructive endovascular methods. METHODS: Nine ruptured BBAs in 9 consecutive patients (2 men and 7 women; mean age 50 years, range 42-57 years) were treated using reconstructive endovascular methods between January 2006 and November 2007. Treatment methods and angiographic and clinical outcomes were retrospectively evaluated. RESULTS: All 9 BBAs were initially treated with stent-assisted coil (SAC) embolization. This was followed by a second stent insertion using the stent-within-a-stent (SWS) technique in 3, covered stent placement in 3, and SAC embolization alone in 3. All 3 patients who underwent SWS placement had excellent outcomes (Glasgow Outcome Scale Score 5) with complete angiographic resolution of the BBAs. There were no treatment-related complications in the SWS group. Two of the 3 patients who received covered stents had excellent outcomes (Glasgow Outcome Scale Score 5) and complete occlusion of the BBA was achieved. The remaining patient who received a covered stent died of ICA rupture during the procedure. Aneurysm regrowth without rebleeding occurred in the 3 patients who underwent SAC embolization. Two of the 3 recurrent BBAs were treated with coil embolization with a second stent insertion, and as a result these belonged to the SWS group. The other recurrent BBA was treated with a covered stent. Of the 8 surviving patients, 5 underwent SWS, and 3 underwent covered stent placement. All surviving patients had excellent outcomes during the clinical follow-up period (mean 11 months, range 4-26 months); complete BBA resolution and smooth reconstruction of the affected ICA segment was shown on follow-up angiography. CONCLUSIONS: In the present study, the SWS and covered-stent techniques effectively prevented rebleeding and regrowth of the BBA without sacrifice of the ICA. The SWS and covered-stent techniques can be considered an alternative treatment option for BBAs in selected patients in whom ICA sacrifice is not feasible. Stent-assisted coiling alone seems insufficient to prevent BBA regrowth.

Pneumocephalus in patients with orthostatic headache.

Cerebrospinal fluid (CSF) leak or shunt overdrainage is a well-known cause of orthostatic headaches and low CSF pressures. We report two cases of orthostatic headache with pneumocephalus on brain imaging. The orthostatic headache developed after drainage of spinal operation site and epidural block. Brain MRI revealed characteristic findings of CSF hypovolemia including pachymeningeal enhancement and mild subdural fluid collections. Air was also observed in the ventricular or subarachnoid space in both patients, which might enter the subarachnoid or ventricular space during a procedure via the pressure gradient or an injection.

Comparison of high MRI T1 signals with manganese concentration in brains of cynomolgus monkeys after 8 months of stainless steel welding-fume exposure.

Several pharmacokinetic studies on inhalation exposure to manganese (Mn) have already demonstrated that Mn readily accumulates in the olfactory and brain regions. However, a shortening of the magnetic resonance imaging (MRI) T1 relaxation time or high T1 signal intensity in specific sites of the brain, including the globus pallidus and subcortical frontal white matter, as indicative of tissue manganese accumulation has not yet been clearly established for certain durations of known doses of welding-fume exposure in experimental animals. Accordingly, to investigate the movement of manganese after welding-fume exposure, six cynomolgus monkeys were acclimated and assigned to three dose groups: unexposed, low dose (31 mg/m(3) total suspended particulate [TSP], 0.9 mg/m(3) of Mn), and high dose (62 mg/m(3) TSP, 1.95 mg/m(3) of Mn) of total suspended particulate. The primates were exposed to manual metal arc stainless steel (MMA-SS) welding fumes for 2 h per day in an inhalation chamber system equipped with an automatic fume generator. Magnetic resonance imaging (MRI) studies were conducted before the initiation of exposure and thereafter every month. The tissue Mn concentrations were then measured after a plateau was reached regarding the shortening of the MRI T1 relaxation time. A dose-dependent increase in the Mn concentration was found in the lungs, while noticeable increases in the Mn concentrations were found in certain tissues, such as the liver, kidneys, and testes. Slight increases in the Mn concentrations were found in the caudate, putamen, frontal lobe, and substantia nigra, while a dose-dependent noticeable increase was only found in the globus pallidus. Therefore, the present results indicated that a shortening of the MRI T1 relaxation time corresponded well with the Mn concentration in the globus pallidus after prolonged welding-fume exposure.

Diffusion tensor imaging demonstrates focal lesions of the corticospinal tract in hemiparetic patients with cerebral palsy.

The purpose of this study was to use diffusion tensor imaging (DTI) with fiber tractography (FT) to demonstrate focal lesions of the corticospinal tract (CST) in hemiparetic patients with cerebral palsy (CP) who showed no specific focal lesions on conventional brain MRI. Four hemiparetic patients with CP (three left hemiparesis, mean age: 2.5 years, range: 0.9-7.0) and four age-matched controls were recruited. DTI was performed using a 1.5-T system with a synergy-L Sensitivity Encoding head coil. Fractional anisotropy (FA) and apparent diffusion coefficients (ADC) were measured using the region of interest (ROI) method. We estimated the asymmetric anisotropy index (AA) and asymmetric mean diffusivity index (AD) to evaluate the asymmetry between right and left CSTs. All four patients showed interrupted FT at the affected periventricular white matter (PVWM) level compared to that of the opposite side; this was not detected on conventional brain MRI and explained the hemiparesis of these patients. Compared to the data of controls, all patients showed significant AA and AD only at the PVWM level. DTI with FT demonstrated focal lesions at the PVWM level. We conclude that DTI with FT may be a useful modality for investigating focal lesions in hemiparetic patients with CP.

Cognitive dysfunction in 16 patients with carotid stenosis: detailed neuropsychological findings.

BACKGROUND: Impairment of cognitive function is often present in patients with carotid artery stenosis but the details of this dysfunction have rarely been reported. Our purpose was to elucidate the cognitive dysfunction in patients with unilateral severe carotid stenosis using comprehensive neuropsychological testing, and also to identify the specific underlying clinical and radiological factors. METHODS: We analyzed the results of neuropsychological testing, the clinical history, and MR findings in 16 consecutive patients with angiographically proven severe (70-99%) stenosis of the extra cranial internal carotid artery (ICA). Cognitive functions were examined using the Seoul Neuropsychological Screening Battery and the Neglect Battery. We excluded patients with cortical infarction and those with contra lateral ICA occlusion or severe stenosis. RESULTS: Our comprehensive neuropsychological testing revealed obvious cognitive deficits in all patients with unilateral severe ICA stenosis, the most common being frontal executive impairment. The mean cognitive score on the memory test was also significantly lower in patients with symptomatic ICA stenosis than in asymptomatic patients (29.33+/-10.98, mean+/-SD, p < 0.05). The total score on the global cognitive test was significantly lower in patients with an ischemic lesion on MRI than in no lesion patients (113.23+/-34.78, p < 0.05). The presence of symptoms related to the ICA stenosis was related to cognitive dysfunction even when there were no ischemic lesions on MRI. SPECT revealed ipsilateral cortical hypoperfusion in 9 of 12 patients (75%). CONCLUSIONS: Cognitive deficits are common in patients with unilateral severe ICA stenosis. Our findings suggest that an additional mechanism beyond the structural lesion such as chronic hypoperfusion may affect cognitive function in patients with high-grade ICA stenosis.

Diffusion-Weighted MRI in Recurrent Wernicke's Encephalopathy: a Remarkable Cerebellar Lesion.

We report unusual MRI findings (including those from diffusion-weighted imaging (DWI)) in a patient with recurrent Wernicke's encephalopathy with a remarkable cerebellar lesion. DWI showed high signal intensities in the superior portion of the cerebellar hemisphere and vermis area. After thiamine administration, clinical symptoms improved and the lesions with high signal intensities disappeared on follow-up DWI.