The Larmor frequency shift of a white matter magnetic microstructure model with multiple sources

Magnetic susceptibility imaging may provide valuable information about chemical composition and microstructural organization of tissue. However, its estimation from the MRI signal phase is particularly difficult as it is sensitive to magnetic tissue properties ranging from the molecular to the macroscopic scale. The MRI Larmor frequency shift measured in white matter (WM) tissue depends on the myelinated axons and other magnetizable sources such as iron-filled ferritin. We have previously derived the Larmor frequency shift arising from a dense medium of cylinders with scalar susceptibility and arbitrary orientation dispersion. Here, we extend our model to include microscopic WM susceptibility anisotropy as well as spherical inclusions with scalar susceptibility to represent subcellular structures, biologically stored iron, and so forth. We validate our analytical results with computer simulations and investigate the feasibility of estimating susceptibility using simple iterative linear least squares without regularization or preconditioning. This is done in a digital brain phantom synthesized from diffusion MRI measurements of an ex vivo mouse brain at ultra-high field.

Infectious Diseases and Basal Ganglia Calcifications: A Cross-Sectional Study in Patients with Fahr's Disease and Systematic Review

Background: It is unclear whether patients with basal ganglia calcifications (BGC) should undergo infectious disease testing as part of their diagnostic work-up. We investigated the occurrence of possibly associated infections in patients with BGC diagnosed with Fahr's disease or syndrome and consecutively performed a systematic review of published infectious diseases associated with BGC. Methods: In a cross-sectional study, we evaluated infections in non-immunocompromised patients aged ≥ 18 years with BGC in the Netherlands, who were diagnosed with Fahr's disease or syndrome after an extensive multidisciplinary diagnostic work-up. Pathogens that were assessed included the following: Brucella sp., cytomegalovirus, human herpesvirus type 6/8, human immunodeficiency virus (HIV), Mycobacterium tuberculosis, rubella virus, and Toxoplasma gondii. Next, a systematic review was performed using MEDLINE and Embase (2002-2023). Results: The cross-sectional study included 54 patients (median age 65 years). We did not observe any possible related infections to the BGC in this population. Prior infection with Toxoplasma gondii occurred in 28%, and in 94%, IgG rubella antibodies were present. The positive tests were considered to be incidental findings by the multidisciplinary team since these infections are only associated with BGC when congenitally contracted and all patients presented with adult-onset symptoms. The systematic search yielded 47 articles, including 24 narrative reviews/textbooks and 23 original studies (11 case series, 6 cross-sectional and 4 cohort studies, and 2 systematic reviews). Most studies reported congenital infections associated with BGC (cytomegalovirus, HIV, rubella virus, Zika virus). Only two studies reported acquired pathogens (chronic active Epstein-Barr virus and Mycobacterium tuberculosis). The quality of evidence was low. Conclusions: In our cross-sectional study and systematic review, we found no convincing evidence that acquired infections are causing BGC in adults. Therefore, we argue against routine testing for infections in non-immunocompromised adults with BGC in Western countries.

An aggressive dural arteriovenous fistula manifested by unilateral subcortical calcification and cerebral edema: A case report

Unilateral subcortical calcifications are unique radiographic findings indicating specific focal pathologies. When the lesion is accompanied by edema, cerebral neoplasm usually leads to a differential diagnosis. This report presents a case of unilateral subcortical calcification and edema that resulted in cerebral hemorrhage and a subsequent diagnosis of an aggressive dural arteriovenous fistula. A man in his 60s presented with left hemianopsia and a progressive headache for over 6 months. Initial computed tomography revealed unilateral subcortical calcification and cerebral edema in the right occipital lobe, raising the suspicion of oligodendroglioma. However, 10 days later, a cerebral hemorrhage occurred in the lesion. Magnetic resonance imaging revealed flow void clusters and dilatation of the bilateral external carotid arteries and cortical veins, indicating a dural arteriovenous fistula. Cerebral angiography confirmed the presence of a parasagittal dural arteriovenous fistula (Borden type III). The patient was successfully treated with trans-arterial embolization using Onyx. Thus, calcifications with edema are more commonly associated with cerebral neoplasms; however, in this case, they indicated the presence of a dural arteriovenous fistula with severe corticovenous reflux. The presented case highlights the importance of recognizing these imaging features in dural arteriovenous fistulas and raises awareness of the potential danger of early hemorrhage after diagnosis. Therefore, timely evaluation of cranial vessels is essential in cases of unilateral subcortical calcification and edema to facilitate the early detection and management of aggressive dural arteriovenous fistulas.

Relationship Between Quantitative Tumor Consistency and Pathological Factors in Intracranial Meningioma

BACKGROUND

The consistency of intracranial meningiomas is an important clinical factor because it affects the success of surgical resection. This study aimed at identifying and quantitatively measuring pathological factors that contribute to the consistency of meningiomas. Furthermore, we investigated the relationship between these factors and preoperative neuroradiological imaging.

METHODS

We analyzed 42 intracranial meningioma specimens, which had been removed at our institution between October 2012 and March 2018. Consistency was measured quantitatively after resection using an industrial stiffness meter. For pathological evaluation, we quantitatively measured the collagen-fiber content through binarization of images of Azan-Mallory-stained section. We assessed calcification and necrosis semi-quantitatively using images acquired of Hematoxylin and Eosin stained samples. The relationship between collagen-fiber content rate and imaging findings was examined.

RESULTS

The content of collagen fibers significantly positively correlated with meningioma consistency (p < 0.0001). Collagen-fiber content was significantly higher in low- and iso-intensity regions compared with high-intensity regions on the magnetic resonance T2-weighted images (p = 0.0148 and p = 0.0394, respectively). Calcification and necrosis showed no correlation with tumor consistency.

CONCLUSIONS

The quantitative hardness of intracranial meningiomas positively correlated with collagen-fiber content; thus, the amount of collagen fibers may be a factor that determines the hardness of intracranial meningiomas. Our results demonstrate that T2-weighted images reflect the collagen-fiber content and are useful for estimating tumor consistency preoperatively and non-invasively.

Evaluation of prevalence and dimension of Pineal Gland Calcification by cone-beam computed tomography (CBCT)

Abstract Objective: This study aimed to investigate the prevalence and dimensions of pineal gland calcification using cone-beam computed tomography (CBCT) in patients undergoing dental treatment. Materials and Methods: CBCTs that localized pineal gland in the fov range was selected in this retrospective study. The presence of pineal gland calcification (PGC) was noted. Vertical, horizontal and areal measurements were made by a single observer (M.S). Variables such as age, gender for each patient were recorded using previous clinical examination data. Results: The prevalence of pineal gland calcification was 33.64% (female to male ratio 3:2). The difference between males and females was not significant (p&gt;0.05). PGC was highly seen in older patients when compared with younger patients (p:000). The average vertical and horizontal dimension of PGC was 2,56±0,98mm and 3,39±1,29 mm respectively. The average total calcified area was 5,45±3,75 mm2. Conclusion: This study did not find any correlation between age, gender, and linear measurements. However, the average calcified are in men was found to be significantly higher than in women.

Frequency, shape, and estimated volume of intracranial physiologic calcification in different age groups investigated by brain computed tomography scan: a retrospective study

Intracranial calcification is referred to calcification of parenchyma and vascular structures in brain which can be physiologic or pathologic. This study was conducted with the purpose of investigating the frequency, location, pattern, dimensions and estimated volume of intracranial physiologic calcification (IPC) by computer tomography in different age groups. In this cross-sectional retrospective study, brain computed tomography scans of 216 patients were analyzed in 9 age groups each containing 24 patients from 2 to 89 years old. Data were analyzed by SPSS software using one way analysis of variance (ANOVA, post hoc Tukey), chi square, and linear regression tests (P≤0.05 was considered significant). Rate of calcification in different areas were as follows: pineal gland (75.0%), habenula (36.4%), pineohabenula (15.0%), right lateral ventricle choroid plexus (RCP) (67.7%), left lateral ventricle choroid plexus (LCP) (62.7%), falx cerebri (26.8%), petroclinoid ligament (13.2%), tentorium cerebelli (6.8%), third ventricle choroid plexus (0.9%), fourth ventricle choroid plexus (2.7%), basal ganglia (0.9%). A significant correlation exists between the presence of calcification in pineal, habenula, RCP, and LCP (P≤0.001). Nodular shape of calcification was dominant (47.9%). Estimated volume of pineal calcification showed increased levels in group 8 (70–79 years old) compared to group 2 (10–19 years old) (P≤0.05). Since the accurate description of radiologic appearance of IPCs (location, shape, and size) accompanied with age and clinical manifestation is of great importance in diagnosis and distinguishing from pathologic calcification—for example in patients with melatonin dysregulation or schizophrenic patients—this study was required.

Emerging Applications for Quantitative Susceptibility Mapping in the Detection of Traumatic Brain Injury Pathology

Traumatic brain injury (TBI) is a common but heterogeneous injury underpinned by numerous complex and interrelated pathophysiological mechanisms. An essential trace element, iron is abundant within the brain and involved in many fundamental neurobiological processes, including oxygen transportation, oxidative phosphorylation, myelin production and maintenance, as well as neurotransmitter synthesis and metabolism. Excessive levels of iron are neurotoxic and thus iron homeostasis is tightly regulated in the brain, however, many details about the mechanisms by which this is achieved are yet to be elucidated. A key mediator of oxidative stress, mitochondrial dysfunction and neuroinflammatory response, iron dysregulation is an important contributor to secondary injury in TBI. Advances in neuroimaging that leverage magnetic susceptibility properties have enabled increasingly comprehensive investigations into the distribution and behaviour of iron in the brain amongst healthy individuals as well as disease states such as TBI. Quantitative Susceptibility Mapping (QSM) is an advanced neuroimaging technique that promises quantitative estimation of local magnetic susceptibility at the voxel level. In this review, we provide an overview of brain iron and its homeostasis, describe recent advances enabling applications of QSM within the context of TBI and summarise the current state of the literature. Although limited, the emergent research suggests that QSM is a promising neuroimaging technique that can be used to investigate a host of pathophysiological changes that are associated with TBI.

Case Report: Two Novel Frameshift Mutations in SLC20A2 and One Novel Splice Donor Mutation in PDGFB Associated With Primary Familial Brain Calcification

Primary familial brain calcification (PFBC, OMIM#213600), also known as Fahr's disease, is characterized by bilateral and symmetric brain calcification in the basal ganglia (globus pallidus, caudate nucleus, and putamen), thalamus, subcortical white matter, and cerebellum. PFBC can be caused by loss-of-function mutations in any of the six known causative genes. The most common clinical manifestations include movement disorders, cognitive impairment, and neuropsychiatric signs that gradually emerge in middle-aged patients. To broaden the PFBC mutation spectrum, we examined nine members of a family with PFBC and two sporadic cases from clinical departments, and sequenced all PFBC-causative genes in the index case. Two novel frameshift mutations in SLC20A2 [NM_001257180.2; c.806delC, p.(Pro269Glnfs^*49) and c.1154delG, p.(Ser385Ilefs^*70)] and one novel splice donor site mutation (NM_002608.4, c.456+1G>C, r.436_456del) in PDGFB were identified in the patient cohort. c.806delC co-segregated with brain calcification and led to SLC20A2 haploinsufficiency among the affected family members. The c.456+1G>C mutation in PDGFB resulted in aberrant mRNA splicing, thereby forming mature transcripts containing an in-frame 21 base pair (bp) deletion, which might create a stably truncated protein [p.(Val146_Gln152del)] and exert a dominant negative effect on wild-type PDGFB. All three mutations were located in highly conserved regions among multiple species and predicted to be pathogenic, as evaluated by at least eight common genetic variation scoring systems. This study identified three novel mutations in SLC20A2 and PDGFB, which broadened and enriched the PFBC mutation spectrum.

Calcified brain metastases may be more frequent than normally considered

Objectives

To verify the incidence of calcified brain metastases (CBM), illustrating the different presentation patterns and histology of primary tumor.

Methods

A series of 1002 consecutive brain computed tomography (CT) scans of patients with known primary tumors was retrospectively assessed. CBM were defined by the presence of calcification within intra-axial-enhancing lesions; identification of CBM was based on visual examination and ROI analysis (> 85 Hounsfield units). Also, calcifications in the primary tumor of all patients with brain metastases were evaluated. In CBM patients, we investigated the type of calcifications (punctate, nodular, cluster, ring, coarse), the histology of primary tumor, and if a previous RT was performed.

Results

Among 190 (18.9%) patients with brain metastatic disease, 34 presented with CBM (17.9%). Sixteen patients were previously treated with RT, while 18 presented calcifications ab initio (9.5% of all brain metastases). The majority of patients with CBM had a primitive lung adenocarcinoma (56%), followed by breast ductal invasive carcinoma (20%) and small cell lung carcinoma (11.8%). CBM were single in 44.1% of patients and multiple in 55.9%. With regard to the type of calcifications, the majority of CBM were punctate, without specific correlations between calcification type and histology of primary tumor. No patients with ab initio CBM had calcifications in primary tumor.

Conclusion

In conclusion, our data show that CBM are more common than usually thought, showing an incidence of 9.5% ab initio in patients with brain metastases. This study underlines that neuroradiologists should not overlook intraparenchymal brain calcifications, especially in oncologic patients.

Key Points

• Among the differential diagnosis of brain intraparenchymal calcifications, metastases are considered uncommon and found predominantly in patients treated with radiotherapy (RT).

• Our data show that CBM are more common than usually thought, showing an incidence of 9.5% ab initio in patients with brain metastases.

• A proportion of intraparenchymal brain calcifications, especially in oncologic patients, might represent evolving lesions and neuroradiologists should not overlook them to avoid a delay in diagnosis and treatment.

Intracranial calcifications on CT: an updated review

Intracranial calcifications are frequently encountered in non-contrast computed tomography scan in both adult and pediatric age groups. They refer to calcifications within the brain parenchyma or vasculature and can be classified into several major categories: physiologic/age-related, dystrophic, congenital disorders/phakomatoses, infectious, vascular, neoplastic, metabolic/endocrine, inflammatory and toxic diseases. In this updated review, we present a wide spectrum of intracranial calcifications from both pediatric and adult populations focusing on their pattern, size and location.

Assessment of Physiological Intracranial Calcification in Healthy Adults Using 18F-NaF PET/CT

The aim of this research study was to determine the role of 18F-Sodium fluoride (NaF) PET/CT imaging in the assessment of physiologic molecular calcification in the intra-cranial structures. We also examined the association of NaF accumulation with age as well as Hounsfield unit (HU) in certain anatomical sites that are known to calcify with normal aging. Methods: A total of 78 healthy subjects from the Cardiovascular Molecular Calcification Assessed by 18F-NaF PET/CT (CAMONA) clinical trial (38 females and 40 males) were included in this retrospective study. The mean age was 45.28 ±14.15 years (21-75). Mean standardized uptake values (SUVmean) was used to measure NaF accumulation in the choroid plexus and epithalamus (pineal gland and habenula). Maximum HU was also measured for each ROI. Correlation analysis was conducted to assess the association between parameters. Results: Mean SUVmean was 0.42 ± 0.26 in the right choroid plexus, 0.39 ±25 in the left choroid plexus, and 0.23±0.08 in the epithalamus. Significant positive correlations were present between NaF uptake and age in the right choroid plexus (r=0.61, P < 0.0001), left choroid plexus (r=0.63, p<0.0001), and epithalamus (r=0.36, P = 0.001). NaF uptake significantly correlated with HU in the right choroid plexus (r=0.52, P < 0.0001), left choroid plexus (r=0.57, p<0.0001), and epithalamus (r=0.25, P = 0.03). Conclusion: NaF could be used in the assessment of physiological calcification in several intracranial structures. We report significant associations between NaF uptake and aging as well as HU in the calcified choroid plexus and epithalamus. Our findings further support the growing interest to utilize NaF for detecting extra-osseous, molecular calcification, and this powerful probe has potential applications in the evaluation of various age-related, neurodegenerative brain processes.

Revised diagnostic criteria for neurocysticercosis

BACKGROUND

A unified set of criteria for neurocysticercosis (NCC) has helped to standardize its diagnosis in different settings.

METHODS

Cysticercosis experts were convened to update current diagnostic criteria for NCC according to two principles: neuroimaging studies are essential for diagnosis, and all other information provides indirect evidence favoring the diagnosis. Recent diagnostic advances were incorporated to this revised set.

RESULTS

This revised set is structured in absolute, neuroimaging and clinical/exposure criteria. Absolute criteria include: histological confirmation of parasites, evidence of subretinal cysts, and demonstration of the scolex within a cyst. Neuroimaging criteria are categorized as major (cystic lesions without scolex, enhancing lesions, multilobulated cysts, and calcifications), confirmative (resolution of cysts after cysticidal drug therapy, spontaneous resolution of single enhancing lesions, and migrating ventricular cysts on sequential neuroimaging studies) and minor (hydrocephalus and leptomeningeal enhancement). Clinical/exposure criteria include: detection of anticysticercal antibodies or cysticercal antigens by well-standardized tests, systemic cysticercosis, evidence of a household Taenia carrier, suggestive clinical manifestations, and residency in endemic areas. Besides patients having absolute criteria, definitive diagnosis can be made in those having two major neuroimaging criteria (or one major plus one confirmative criteria) plus exposure. For patients presenting with one major and one minor neuroimaging criteria plus exposure, definitive diagnosis of NCC requires the exclusion of confounding pathologies. Probable diagnosis is reserved for individuals presenting with one neuroimaging criteria plus strong evidence of exposure.

CONCLUSIONS

This revised set of diagnostic criteria provides simpler definitions and may facilitate its more uniform and widespread applicability in different scenarios.

Vascular malformation mimicking multiple sclerosis active plaque: Usefulness of susceptibility weighted imaging (SWI) to perform correct diagnosis

Brain focal hyperdensity areas are common findings in computed tomography examinations, often further evaluated in magnetic resonance imaging exams. These are usually haemosiderin and calcified perivascular clusters known as cerebral microbleeds and may be secondary signs of brain disorders. Cerebral microbleeds are paramagnetic and ferromagnetic substances determining magnetic field inhomogeneity. Susceptibility weighted imaging (SWI) performed at 3T with phase post-processing is very useful in evaluating this field variation. In fact in the past decade SWI has been increasingly reported for its clinical value in adults with neurologic disorders, traumas, arterial venous malformations, occult venous diseases, tumours and functional brain imaging. The occasional computed tomography findings of single or multiple focal hyperdense areas can mimic many of these brain disorders and lead to misinterpretations. For these reason it is useful to have a more detailed diagnosis with MRI brain examination. The authors highlight the role of SWI sequence in the differential diagnosis among active plaque, vascular malformation and haemorrhagic lesion in a case report of a 41-year-old woman suffering from multiple sclerosis with a focal hyperdense area reported in a computed tomography brain examination.

Imaging of adult ocular and orbital pathology--a pictorial review

Orbital pathology often presents a diagnostic challenge to the reporting radiologist. The aetiology is protean, and clinical input is therefore often necessary to narrow the differential diagnosis. With this manuscript, we provide a pictorial review of adult ocular and orbital pathology.