Spinal Infections.

Spinal cord infections can present with a wide variety of imaging findings, depending on the pathogen and the host's immune status. Infectious myelitis can have a characteristic distribution of lesions within the spinal cord, which refine the differential disease. Some spinal infections do not show typical imaging features, and many noninfectious may mimic spinal infections with similar MR imaging findings. Infectious arachnoiditis and meningitis must be differentiated from neoplasms. Spondylitis has many mimickers and requires careful interpretations of images, clinical findings, and follow-up information.

Volumetric Assessment of Hippocampus and Subcortical Gray Matter Regions in Alzheimer Disease and Amnestic Mild Cognitive Impairment.

BACKGROUND: Quantitative MRI assessment methods have limited utility due to a lack of standardized methods and measures for Alzheimer disease (AD) and amnestic mild cognitive impairment (aMCI). OBJECTIVE: To employ a relatively new and easy-to-use quantitative assessment method to reveal volumetric changes in subcortical gray matter (GM) regions, hippocampus, and global intracranial structures as well as the diagnostic performance and best thresholds of total hippocampal volumetry in individuals with AD and those with aMCI. METHOD: A total of 74 individuals-37 with mild to moderate AD, 19 with aMCI, and 18 with normal cognition (NC)-underwent a 3T MRI. Fully automated segmentation and volumetric measurements were performed. RESULTS: The AD and aMCI groups had smaller volumes of amygdala, nucleus accumbens, and hippocampus compared with the NC group. These same two groups had significantly smaller total white matter volume than the NC group. The AD group had smaller total GM volume compared with the aMCI and NC groups. The thalamus in the AD group showed a subtle atrophy. There were no significant volumetric differences in the caudate nucleus, putamen, or globus pallidus between the groups. CONCLUSION: The amygdala and nucleus accumbens showed atrophy comparable to the hippocampal atrophy in both the AD and aMCI groups, which may contribute to cognitive impairment. Hippocampal volumetry is a reliable tool for differentiating between AD and NC groups but has substantially less power in differentiating between AD and aMCI groups. The loss of total GM volume differentiates AD from aMCI and NC.

DWI-based MR thermometry: could it discriminate Alzheimer's disease from mild cognitive impairment and healthy subjects?

PURPOSE: The aim of this study is to compare lateral ventricular cerebrospinal fluid (CSF) temperature of the patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy subjects (HS) using diffusion-weighted imaging (DWI)-based magnetic resonance (MR) thermometry. METHODS: Seventy-two patients (37 AD, 19 MCI, 16 HS) who underwent 3-T MR examination from September 2018 to August 2019 were included in this study. Smoking habits, education level, disease duration, and comorbidity status were recorded. Patients were assessed using Mini-Mental State Examination (MMSE) and the Clinical Dementia Rating (CDR) score. Brain temperatures were measured using DWI-based MR thermometry. Group comparisons of brain temperature were performed using the Pearson chi-square, Mann-Whitney, and Kruskal-Wallis tests. Further analysis was performed using the post hoc Bonferroni test. Receiver operating characteristic (ROC) analysis was also used. RESULTS: A CDR score of 0.5, 1, and 2 was 2 (5.4%), 14 (37.8%), and 21 (56.8%) in AD, respectively. The median MMSE score had significant differences among groups and also in pairwise comparisons. The median CSF temperature (°C) values showed statistically significant difference among groups (HS: 38.5 °C, MCI: 38.17 °C, AD: 38.0 °C). The post hoc Mann-Whitney U test indicated a significant difference between AD patients and HS (p = 0.009). There were no significant CSF temperature differences in other pairwise comparisons. CONCLUSION: Lower CSF temperatures were observed in AD patients than in HS, probably due to decreased brain metabolism in AD. DWI-based MR thermometry as a noninvasive imaging method enabling the measurement of CSF temperatures may contribute to the diagnosis of AD.

Oligemia, Penumbra, Infarction: Understanding Hypoperfusion with Neuroimaging.

Despite recent progress in the treatment of acute ischemic stroke with multiple trials demonstrating improved clinical outcome associated with endovascular thrombectomy up to 24 hours after onset, there is potential opportunity for optimal patient selection and treatment algorithm to further improve treatment outcome. Current limitation is in part caused by inconsistency of imaging protocols and imaging-based definitions of oligemia, penumbra, and infarction core within the various hypoperfusion states. To truly maximize the impact of imaging in acute ischemic stroke, imaging definitions of hypoperfusion states need to be more consistent and validated to correctly reflect different severities of ischemic injury.

Pyogenic spinal infections.

Spinal infections are a spectrum of disease comprising spondylitis, diskitis, spondylodiskitis, pyogenic facet arthropathy, epidural infections, meningitis, polyradiculopathy, and myelitis. Inflammation can be caused by pyogenic, granulomatous, autoimmune, idiopathic, and iatrogenic conditions. In an era of immune suppression, tuberculosis, and HIV epidemic, together with worldwide socioeconomic fluctuations, spinal infections are increasing. Despite advanced diagnostic technology, diagnosis of this entity and differentiation from degenerative disease, noninfective inflammatory lesions, and spinal neoplasms are difficult. Radiological evaluations play an important role, with contrast-enhanced MR imaging the modality of choice in diagnosis, evaluation, treatment planning, interventional treatment, and treatment monitoring of spinal infections.

Spinal brucellosis.

Spinal involvement in human brucellosis is a common condition and a significant cause of morbidity and mortality, particularly in endemic areas, because it is often associated with therapeutic failure. Most chronic brucellosis cases are the result of inadequate treatment of the initial episode. Recognition of spinal brucellosis is challenging. Early diagnosis is important to ensure proper treatment and decrease morbidity and mortality. Radiologic evaluation has gained importance in diagnosis and treatment planning, including interventional procedures and monitoring of all spinal infections.

Presurgical evaluation of mesial temporal lobe epilepsy with multiple advanced MR techniques at 3T.

BACKGROUND AND PURPOSE: Accurate localization of the epileptogenic zone is essential for successful surgical treatment of mesial temporal lobe epilepsy (MTLE). The aim of this study was to analyze and compare the hippocampal volumetry (HV), MR spectroscopy (MRS), Dynamic susceptibility contrast (DSC) and pulsed arterial spin labeling (pASL) perfusion techniques in a large sample size of refractory MTLE patients. MATERIALS AND METHODS: Forty-two patients with medically refractory MTLE who underwent preoperative evaluation and eleven normal controls were studied. Pathologic and control hippocampi were compared in terms of hippocampal volume, metabolite ratios and relative hippocampal perfusion values. By using cut-off points and asymmetry indexes, percentages of performance indicators for each technique were calculated in groups of MR (+), MR (-) and bilateral MTLE. RESULTS: For all techniques, a statistically significant difference was found between the pathologic and control hippocampus groups (P<0.001). Also, all of them except HV had diagnostic value in groups of MR (-) and bilateral MTLE. CONCLUSION: HV, MRS, DSC and pASL have achieved comparable performance and each of them provides important information about the lateralization of epileptogenic focus. Among those, pASL and MRS may easily be used as an adjunct to conventional MR.

Assessment of third ventriculostomy patency with the 3D-SPACE technique: a preliminary multicenter research study.

OBJECT: The goal of this study was to determine the value of the 3D sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) technique in the evaluation of endoscopic third ventriculostomy (ETV) patency. METHODS: Twenty-six patients with ETV were examined using 3-T MRI units. Sagittal-plane 3D-SPACE with variant flip-angle mode, 3D T1-weighted (T1W), and 3D heavily T2-weighted (T2W) images were obtained with isotropic voxel sizes. Also, sagittal-axial plane phase-contrast cine (PC)-MR images were obtained. The following findings were evaluated: diameters of stoma and third ventricle, flow-void sign on 3D-SPACE and PC-MR images, integrity of the third ventricle on heavily T2W images, and quantitative PC-MRI parameters of the stoma. Obtained sequences were evaluated singly, in combination with one another, and all together. RESULTS: The mean area, flow, and velocity values measured at the level of stoma in patients with patent stoma were significantly higher than those measured in patients with closed stoma (p < 0.05). There was significant correlation among PC-MRI, 3D-SPACE, and 3D heavily T2W techniques regarding assessment of ETV patency (p < 0.001). The 3D-SPACE technique provided the lowest rate of ambiguous results. CONCLUSIONS: The 3D-SPACE technique seems to be the most efficient one for determination of ETV patency. The authors suggest the use of 3D-SPACE as a stand-alone first-line sequence in addition to routine brain MRI protocols in assessing patients with ETV, thereby decreasing scan time and reserving the use of a combination of additional sequences such as PC-MRI and 3D heavily T2W images in suspicious or complex cases.

Functional MRI compliance in children with attention deficit hyperactivity disorder.

PURPOSE: We aimed to test the effect of prescan training and orientation in functional magnetic resonance imaging (fMRI) in children with attention deficit hyperactivity disorder (ADHD) and to investigate whether fMRI compliance was modified by state anxiety. METHODS: Subjects included 77 males aged 6-12 years; there were 53 patients in the ADHD group and 24 participants in the healthy control group. Exclusion criteria included neurological and/or psychiatric comorbidities (other than ADHD), the use of psychoactive drugs, and an intelligence quotient outside the normal range. Children were individually subjected to prescan orientation and training. Data were acquired using a 1.5 Tesla scanner and an 8-channel head coil. Functional scans were performed using a standard neurocognitive task. RESULTS: The neurocognitive task led to reliable fMRI maps. Compliance was not significantly different between ADHD and control groups based on success, failure, and repetition rates of fMRI. Compliance of ADHD patients with extreme levels of anxiety was also not significantly different. CONCLUSION: The fMRI compliance of ADHD children is typically lower than that of healthy children. However, compliance can be increased to the level of age-matched healthy control children by addressing concerns about the technical and procedural aspects of fMRI, providing orientation programs, and performing on-task training. In patients thus trained, compliance does not change with the level of state anxiety suggesting that the anxiety hypothesis of fMRI compliance is not supported.

The relationship of glenoid and humeral version with supraspinatus tendon tears.

The aim of this study was to investigate the relationship of glenohumeral anatomic measurements on MR imaging with supraspinatus tendon tears. The study was approved by the institutional review board and informed consent was obtained from each subject. Forty-two patients (mean age 55.5 years; age range 40-73 years) with supraspinatus tendon tears and 50 asymptomatic shoulders of 32 controls (mean age 43 years; age range 17-69 years) without rotator cuff tears were included. The acromio-glenoid and supraspinatus-glenoid angles were measured on coronal images, the glenoid and humeral head version as well as the bicipital-humeral distance on axial images. Significant differences were found between the patients and controls for both glenoid version and bicipital-humeral distance, which are considered to influence the distribution of forces placed on the cuff (p < 0.05). The patients had a decreased glenoid version by an average of 2.3 degrees (-7.1 +/- 7.8 degrees vs. -4.8 +/- 5.6 degrees), and a decreased bicipital-humeral distance by an average of 2.7 mm (12.1 +/- 3.7 mm vs. 14.8 +/- 4.1 mm). No significant differences were found between these groups for humeral head version and the acromio-glenoid and supraspinatus-glenoid angles, which might contribute to extrinsic impingement by narrowing the supraspinatus tendon outlet. Differences in glenoid and humeral version may be responsible for RC tears by changing the orientation of the rotator cuff and thus increasing shearing stress.

Spinal infections.

Spinal infections have an increasing prevalence among the general population. Definitive diagnosis based solely on clinical grounds is usually not possible and radiological imaging is used in almost all patients. The primary aim of the authors is to present an overview of spinal infections located in epidural, intradural and intramedullary compartments and to provide diagnostic clues regarding different imaging modalities, particularly MRI, to the practicing physicians and radiologists.

Isolated true anterior thoracic meningocele.

Intrathoracic meningocele is rare and is usually associated with neurofibromatosis type I. Most of the reported thoracic meningoceles are not strictly anterior in location, but also lateral or anterolateral. We report a case of true anterior thoracic meningocele with no associated generalized mesenchymal dysplasia.

Intrathecal gadolinium (gadopentetate dimeglumine)-enhanced MR cisternography used to determine potential communication between the cerebrospinal fluid pathways and intracranial arachnoid cysts.

This study was designed to assess the feasibility of intrathecal gadolinium-enhanced magnetic resonance cisternography (MRC) for the evaluation of the presence or absence of communication of cranial arachnoid cysts with the cerebrospinal fluid (CSF) pathways of the central nervous system (CNS). This prospective study included 20 patients (12 males and 8 females) with a mean age of 37 years, who had, as a group, 22 intracranial arachnoid cysts identified on prior CT and/or MR examinations. Routine pre-contrast cranial MR imaging was followed by the intrathecal administration of 0.5 cc gadopentetate dimeglumine (GD) (Magnevist, Schering, Germany). Immediate and delayed (24 h) MR cisternography was then carried out. Eleven of 22 arachnoid cysts showed immediate CSF communication by the demonstration GD-contrast enhancement of the cyst fluid on the immediate post-injection scan. Contrast enhancement of the cyst was observed only on delayed MRC in six patients. MR imaging in five patients demonstrated no contrast enhancement of the arachnoid cysts on either immediate or delayed imaging. Six patients had mild transient post-procedure headache that was relieved by oral analgesics within 24 h. No serious immediate or chronic adverse effects or complications relating to the intrathecal contrast administration were observed. This study showed the relative safety, feasibility and reliability of low-dose intrathecal GD MR imaging in the demonstration of the communication or non-communication of intracranial arachnoid cysts with the CSF pathways of the CNS. In the future, this may have bearing on the selection for surgery of patients with intracranial arachnoid cysts presenting with clinical signs and symptoms potentially related to the location and mass effect of the cyst.

Spinal infections.

Spinal infections can be thought of as a spectrum of disease comprising spondylitis, discitis, spondylodiscitis, pyogenic facet arthropathy, epidural infections, meningitis, polyradiculopathy and myelitis. Radiological evaluations have gained importance in the diagnosis, treatment planning, treatment and treatment monitoring of the spinal infections. Conventional radiographs are usually the initial imaging study. The sensitivity and specificity of the plain radiographs are very low. The sensitivity of CT is higher while it lacks of specificity. Conventional CT has played minor role for the diagnosis of early spondylitis and disc space infection and for follow-up, researches are going on the value of MDCT. MRI is as sensitive, specific and accurate as combined nuclear medicine studies and the method of choice for the spondylitis. Low signal areas of the vertebral body, loss of definition of the end plates and interruption of the cortical continuity, destruction of the cortical margins are typical on T1WI whereas high signal of affected areas of the vertebral body and disc is typical on T2WI. Contrast is mandatory and increases conspicuity, specificity, and observer confidence in the diagnosis and facilitates the treatment planning. Contrast enhancement is the earliest sign and pathognomonic in the acute inflammatory episode and even in the subtle infection then persists to a varying degree for several weeks or months. The outcome of the treatment is influenced by the type of infection and by the degree of neurologic compromise before treatment. There is an increasing move away from surgical intervention towards conservative therapy, percutaneous drainage of abscess or both. It is therefore critical to monitor treatment response, particularly in the immuno-deficient population.