Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Diffusion MRI”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources
PubMed2006

Clinical and imaging metrics for monitoring disease progression in patients with multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune disease of the CNS leading to clinical disability in 250,000-350,000 young adults in the USA and Europe. The disease affects both white matter (WM) and gray matter (GM) tissues of the brain and spinal cord. While WM disease is easily quantified using currently available magnetic resonance imaging (MRI) techniques, identification and quantification of GM disease present a daily challenge. Nonconventional brain and spinal cord MRI techniques, including magnetization transfer, MRI spectroscopy and diffusion tensor imaging, have improved our understanding of MS pathology in the deep GM. The sensitivity of high-resolution MRI obtained at a high magnetic field will improve the detection of spinal cord and brain cortical GM disease. The appropriate use of the above-mentioned techniques has the potential to more accurately explain the level of disability in MS patients.

Cognition Disorders↗
PubMed2004

[Diagnostic value of MR diffusion tensor imaging on radiation-induced early brain injury of nasopharyngeal carcinoma after radiotherapy].

BACKGROUND & OBJECTIVE: MR diffusion tensor imaging (DTI), a new MRI technique, can observe water molecule diffusion non-invasively at molecular level. This study was to assess diagnostic value of DTI on post-radiotherapy brain injury by quantitatively analyzing diffuse features of water in bilateral temporal lobes alba of those nasopharyngeal carcinoma (NPC) patients with normal conventional MRI performances. METHODS: DTI was performed in 13 NPC patients with normal conventional MRI performances after radiotherapy, and 21 healthy controls. Isotropic apparent diffusion coefficient (ADCiso) and anisotropic index (AI) were measured in bilateral temporal lobes alba. RESULTS: ADCiso of patient group was (631.30+/-27.83) x 10(-6) mm2/s, while that of control group was (651.76+/-39.10) x 10(-6) mm2/s (P>0.05). Temporal lobes diffusion AI decreased significantly in patient group, mean fractional anisotropy (FA) was 0.405+/-0.042, mean relative anisotropy (RA) was 0.355+/-0.044, and mean 1 minus volume ratio (1-VR) was 0.192+/-0.042; while those in control group were 0.463+/-0.047, 0.418+/-0.052, and 0.257+/-0.055, respectively (P< 0.01). CONCLUSIONS: DTI can early detect subtle alba changes in NPC patients after radiotherapy, which conventional MRI failed to sense. AI is more sensitive than ADCiso, may better describe the diffuse features of water molecules, and evaluate the temporal lobes alba changes before and after NPC radiotherapy.

Adolescent↗
PubMed1991

Phase II study of ifosfamide with mesna in adult patients with recurrent diffuse astrocytoma.

Sixteen patients who developed CT or MRI scan evidence of recurrent diffuse astrocytoma after radiation therapy and nitrosourea-containing chemotherapy received ifosfamide (2500 mg/m2/day for 3 consecutive days) and mesna (500 mg/m2/dose, 5 doses/day for 3 consecutive days). Toxicity consisted primarily of leukopenia in that 60 percent of patients developed leukocyte nadirs less than 1500/mcL. Excessive somnolence occurred in three patients and may have contributed to a case of fatal pneumonia in one patient but was reversible in the other two. No patient had CT or MRI scan evidence of tumor regression. One patient remains stable at 11.3 + months, but all other patients developed evidence of progressive disease less than 6 months from initiation of therapy. The median times to tumor progression and death were 2.0 and 4.8 months, respectively. In conclusion, while ifosfamide and mesna can be given safely at this dose and schedule, there is no evidence of antitumor effect. The degree of leukopenia observed likely would prevent further dose escalation of ifosfamide or addition of other myelosuppressive agents without additional means of bone marrow support in this population of patients.

Adolescent↗
PubMed2006

Influence of aging on brain gray and white matter changes assessed by conventional, MT, and DT MRI.

BACKGROUND: Conventional MRI can reveal decreases in brain volumes with aging but fails to provide information about the underlying microstructural modifications. Magnetization transfer (MT) and diffusion tensor (DT) MRI can in part overcome these limitations. OBJECTIVE: To investigate the influence of aging on conventional and MT and DT MRI-derived measurements in brain white (WM) and gray (GM) matter. METHODS: Dual-echo, T1-weighted, MT and DT MR images of the brain were obtained in 89 healthy subjects (age range 11 to 76 years). Normalized GM and WM volumes were measured and MT ratio (MTR) and mean diffusivity (MD) histograms produced for both tissue compartments. RESULTS: Normalized brain (r = -0.78), GM (r = -0.75), and WM (r = -0.34) volumes and the number of brain T2 hyperintensities (r = 0.49) were correlated with age. Additionally, all GM MT- and DT-derived parameters also correlated with age (r values ranging from 0.28 to 0.64), whereas only the peak height (ph) of the normal-appearing (NA) WM MD histogram did so (r = -0.34). After correcting for the number of T2 hyperintensities, gender, and the corresponding normalized tissue volumes, only the correlations between age and GM average MD (r = 0.24), GM-MD-ph (r = -0.37), and NAWM-MD-ph (r = -0.29) remained significant. A multivariate regression analysis including both brain tissues variables retained the GM volume (beta = -0.18, SE = 0.02, p < 0.001) and the GM average MD (beta = 45, SE = 19, p = 0.02) as independent predictors of subject's age. CONCLUSIONS: Brain white matter and gray matter have different vulnerabilities to aging. Microstructural imaging is important to achieve a complete picture of the complex changes occurring in the aging brain.

Adolescent↗
PubMed2001

Diffuse venous malformations of the upper limb: morphologic characterization by MRI and venography.

OBJECTIVES: To define the morphologic abnormalities in patients presenting with diffuse pure venous malformations (VM) of the upper extremity. SUBJECTS AND METHODS: A retrospective review of MRI and venography was performed on five patients, aged 6 months to 20 years, with extensive VM of the upper limbs. Abnormalities of major conducting veins were categorized as varicosities, stenoses, and asymmetrical pouches; anomalous venous spaces were classified into confluent lakes, interconnecting channels and spongelike plexiform networks. MRI and venographic data were reviewed separately and then simultaneously in order to establish correlation between types, location, and extent of lesions. RESULTS: In all patients, the percentage of replacement of normal tissues by VM was shown by MRI to be significantly higher in the distal limb than in the proximal limb. Involvement of multiple tissue layers was seen in all cases, including, with a decreasing rate, muscles, tendons, interosseous membrane of the forearm, and bone. Venography showed superficial varicosities, frequently associated with stenoses and assymetric pouches in all patients. Interconnecting channels and venous lakes were noted in half of the segments, typically in muscle and other deep locations, and subcutaneous spongelike lesions were seen in two patients. MRI provided a more accurate evaluation of tissue extent. Venograms better demonstrated morphological details and provided more information about the venous drainage. Direct comparison of MR images with venograms helped to identify and characterize venous lesions on cross-sectional MR data. CONCLUSION: Diffuse VM of the upper extremity are most extensive distally, and all tissues layers can be involved, each with a characteristic morphologic appearance. The morphology of different components of the VM is related to the nature of the surrounding tissue.

Adolescent↗
PubMedDate not supplied

Primary hepatic neuroendocrine carcinoma with multiple metastases: a case report.

We report a rare case of primary hepatic neuroendocrine cell carcinoma with multiple metastases to the liver, lung, diaphragm, bone, and pancreas. The patient was a 45-year-old man with jaundice and a large hepatic tumor measuring 12 x 16 cm at autopsy. Located in the right lobe, it was hyperechoic and inhomogeneous on US, a diffusely low density mass that contained capsule- and septum-like structures enhanced by contrast medium on CT, an inhomogeneously low intensity mass with much lower intensity foci on T1-weighted MRI, and a diffusely high intensity mass containing small higher and lower intensity foci on T2-weighted MRI. These findings are similar to those of a few previously reported cases, but are not specific to this tumor.

Carcinoma, Neuroendocrine↗
PubMed2004

Functional and diffusion-weighted magnetic resonance imaging for visualization of the postthalamic visual fiber tracts and the visual cortex.

Diffusion-weighted magnetic resonance imaging (MRI) offers the possibility to study the course of the cerebral white matter tracts whereas functional MRI (fMRI) provides information about the specific functions of cortical areas. We evaluated the combination of fMRI and diffusion-weighted MRI to detect cortical visual areas with their corresponding visual fiber tracts in 15 healthy controls (age: 23 - 53 years, male : female = 8 : 7). We demonstrated activation within the primary visual cortex and white matter bundles connecting the lateral geniculate body and the striate cortex in all subjects investigated. Additional activation could be appreciated in some subjects within the lateral geniculate bodies (n = 2) and the motion-sensitive area V5 (n = 3). The combination of diffusion-weighted and functional imaging allows visualization of the origin, direction and functionality of large white matter tracts. This will prove helpful for imaging structural connectivity within the brain during functional imaging. Moreover, this technique might provide important information for neurosurgical patients presenting with space-occupying lesions close to the cortical and subcortical visual system since this technique can -- in contrast to diffusion tensor imaging -- easily be adopted into a neuronavigation system and can be performed on all MR scanners capable of diffusion-weighted imaging without specific post-processing programs.

Adult↗
PubMed2001

Menstrual cycle variation of apparent diffusion coefficients measured in the normal breast using MRI.

Recent investigations have shown that tumors may be distinguished from benign lesions in the breast based on differences in apparent diffusion coefficient (ADC) values. The goal of this study was to assess the magnitude of normal variations in the measured ADC of breast parenchyma during the menstrual cycle. Eight healthy female subjects were scanned once a week for 4 weeks, using a diffusion-weighted single-shot fast spin-echo (DW-SSFSE) sequence. The ADC of breast fibroglandular tissue was calculated for each woman at each time point. Results showed a trend of decreased ADC during the second week of the cycle, and increased ADC during the final week. However, no significant influence of menstrual cycle on breast ADC values was identified. The results of this study show that the normal fluctuation of breast ADC is relatively small, and the coefficient of variation was determined to be 5.5% for our group of volunteers during a menstrual cycle. Nonetheless, breast diffusion measurements for tumor differentiation and evaluation of treatment response should be interpreted with consideration of normal variability.

Adult↗
PubMed2005

New developments in the neuroradiological diagnosis of craniocerebral trauma.

Accurate radiographic diagnosis is a cornerstone of the clinical management and outcome prediction of the head-injured patient. New technological advances, such as multi-detector computed tomography (MDCT) scanning and diffusion-weighted magnetic resonance imaging (MRI) have influenced imaging strategy. In this article we review the impact of these developments on the neuroradiological diagnosis of acute head injury. In the acute phase, multi-detector CT has supplanted plain X-ray films of the skull as the initial imaging study of choice. MRI, including fluid-attenuated inversion recovery, gradient echo T2* and diffusion-weighted sequences, is useful in determining the severity of acute brain tissue injury and may help to predict outcome. The role of MRI in showing diffuse axonal injuries is emphasized. We review the different patterns of primary and secondary extra-axial and intra-axial traumatic brain lesions and integrate new insights. Assessment of intracranial hypertension and cerebral herniation are of major clinical importance in patient management. We discuss the issue of pediatric brain trauma and stress the importance of MRI in non-accidental injury. In summary, new developments in imaging technology have advanced our understanding of the pathophysiology of brain trauma and contribute to improving the survival of patients with craniocerebral injuries.

Brain Injuries↗
PubMed2000

MRI of acute experimental intracerebral hematoma.

The purpose of the study was to evaluate the ability of different MR-sequences to detect and delineate experimentally produced hyperacute intracerebral hematomas in rats. Twenty male Sprague-Dawley rats received a unilateral hematoma of various volumes by stereotactic injection of fresh autologous arterial blood into the right caudatoputamen. MRI was performed up to 30 min after-generation of each hematoma. We obtained coronal T2- and T1-weighted spin-echo images. Furthermore we acquired RF-spoiled 2D- and 3D-FLASH images. MR-images were evaluated for signal behavior, location, configuration, size, and volume of each hematoma on a dedicated work station. MR volumetry was correlated to volumetric data obtained from the serial stained histological sections. All hematomas produced signal abnormalities on all sequences in each case. In the majority of cases the hematomas were hypointense. RF-spoiled FLASH 2D- and 3D-sequences showed the best detection of the hematoma owing to their high sensitivity to susceptibility effects. The best correlation between MR- and histological volumetry was found on RF-spoiled FLASH 2D- (corr. 0.81), SE T2- (corr. 0.79), and T1- (corr. 0.74) weighted images. The lowest correlation index was found on the RF-spoiled FLASH 3D-images (corr. 0.51). Signal loss of hematomas on gradient-echo images and--to a lesser extent--spin-echo T2-weighted images due to susceptibility effects can reliably delineate an acute state, whereas conventional MR scans of ischemic stroke may be normal. MRI may thus be the imaging modality of choice in patients with acute brain attack, especially when it is planned to perform diffusion and perfusion MRI before thrombolytic therapy.

Acute Disease↗
PubMed2002

[An autopsy case with subacute spinal cord disease showing progressive paraplegia].

We report a 72-year-old woman who died of respitory failure. History included onset of diabetes mellitus at the age of 67 years and hypertension at the age of 72 years. The patient had been in good health otherwise until 2000, when she had onset of numbness or tingling of the bilateral lower limbs. On December 3, 2000, she was admitted to a hospital in the vicinity of her home because of the above-mentioned complaints. Neurological examinations revealed progressive paraplegia. Symptoms and signs suggested Guillain-Barré syndrome. Examinations of cerebrospinal fluids revealed cell count of 338/3 (mono 72%, poly 18%) and protein value of 100 mg/dl. Later the patient course deteriorated. On December 15, 2000, she was admitted to Hakujikai Memorial Hospital for the second time. Ten days later, MRI examination showed diffuse swelling of the spinal cord from the cervical (C 3/4) level to the thoracic level. Gd-enhanced T 1-weighted MRI performed 22 days later showed a partially enhanced lesion at the thoracic (Th 5/6) level of the spinal cord. The patient was treated with steroid therapy (methylprednisolone 500 mg/dl). She died of respiratory failure on January 6, 2001. The patient was presented in a neurological CPC. Neurological and imaging findings suggested a transverse myelopathy. However, there were several points in this case that were unusual for a typical transverse myelopathy, such as total sensory loss below spinal segments of thoracic level (Th 5) and motor weakness of the upper limbs of upper segment of the same level. A clinical neurologist concluded that the patient had subacute transverse myelopathy with fused multiple pathy pathologic lesions. We discussed whether this case was a transverse myelopathy or multiple sclerosis. Post mortem examination revealed acute necrotic myelopathy affecting the spinal cord from the second cervical to the tenth thoracic vertebrae, with conspicuous infiltration of CD 68-positive macrophages involving both gray and white matter, partially necrotic associated with scattered UCHL-1 dominants lymphocytic infiltration of T cells around vessels. There were relatively older lesions with demyelinating features in the spinal roots that were particularly dominant in the anterior roots. No demyelinated plaques in the optic chiasm, tracts and nerves, or in the cerebero-cerebellar white matter were found. Systemic pathological diagnosis was lung edema with fresh hemorrhage, pancreatic atrophy consistent with diabetes mellitus and choleductlithiasis.

Aged↗
PubMed2004

Proton and hyperpolarized helium magnetic resonance imaging of radiation-induced lung injury in rats.

PURPOSE: To assess the usefulness of hyperpolarized helium (3He) MRI, including apparent diffusion coefficient measurements, in the detection and evaluation of radiation-induced lung injury in rats. METHODS AND MATERIALS: Female Fischer-344 rats were treated to the right lung with fractionated dose of 40 Gy (5 x 8 Gy) using 4-MV photons. Conventional proton (1H) and hyperpolarized (3He) MRI were used to image the lungs 3-6 months after radiation treatment. Apparent diffusion coefficient (ADC) maps of hyperpolarized 3He in the lungs were calculated using a nonlinear, least-squares fitting routine on a pixel-by-pixel basis. After imaging, lungs were processed for histologic assessment of damage. RESULTS: The effect of radiation was time dependent with progressive right lung damage ranging from mild to moderate at 3 months to severe fibrosis with structural deformation at 6 months after radiation. There was a significant decrease in the apparent diffusion coefficient of hyperpolarized 3He gas in radiation-treated lungs. Areas of decreased ADC in the lungs correlated with fibrosis shown by histology. CONCLUSION: This is the first study to show that hyperpolarized 3He MRI can detect radiation-induced lung injury noninvasively. Reduced hyperpolarized 3He ADC values postradiation likely reflect reduced alveolar volumes associated with fibrosis of the interstitium. Future studies at earlier time points may determine whether this noninvasive imaging technique can detect lung damage before clinical symptoms. Development of this new approach of magnetic resonance lung imaging in the rat model of radiation-induced lung injury will increase the ability to develop appropriate algorithms and more accurate models of the normal tissue complication probability.

Animals↗
PubMed1990

[A case of membranous lipodystrophy (Nasu) with diffuse cerebral white matter involvement and cerebellar atrophy on brain CT and MRI].

A 37-year-old female was admitted to our hospital because of progressive dementia and gait disturbance. She was healthy until 34 years of age when she had difficulty in walking and memory disturbance with personality changes. At age 36, she developed urinary incontinence and dementia. The neurological examination demonstrated euphoric mental state, emotional incontinence, severe dementia, paraplegia, dysmetria, choreic movements in both arms and urinary incontinence. Diffuse hyperreflexia and bilateral Babinski signs were observed. Routine laboratory examination showed slightly increased erythrocyte sedimentation rate and alkaline phosphatase. Electroencephalogram revealed diffuse irregular slow waves. X-ray film of the ulnar bone revealed osteoporotic and cystic lesions. The biopsy of the left tibial bone showed a specific membranous cystic structure. Computerized tomography (CT) of the brain showed symmetric, diffuse low density areas in the cerebral white matter and severe atrophy of the cerebellum. T2-weighted magnetic resonance imaging (MRI) revealed diffuse high intensity areas in the cerebral white matter. The present case is characterized by diffuse changes in cerebral white matter and cerebellar atrophy, which have been never reported in Nasu-Hakola disease. The diffuse cerebral white matter changes shown by CT and MRI appear to indicate that this patient is the first case of leukodystrophy of sudanophilic type since the original case reported by Nasu et al.

Adult↗
PubMed1996

Measuring Diffusion in the Presence of Material Strain

Material strain during the course of diffusion encoding by MRI will in general change the observed diffusional signal losses. These changes will occur even when the material returns cyclically to its initial location during the diffusion-evolution period. This effect derives from the modification of the local spatial modulation k of spin phase within a sample by a material deformation \font\serif=cmss10 at 10pt $\hbox{\serif F}$ as k --> $\hbox{\serif F}^{\rm 1T}$ k, resulting in an observed diffusion tensor $\hbox{\serif D}^{\rm obs} = {{1}\over{\Delta}} \int^{\Delta}_0 \hbox{\serif U}(t)^{-1} \hbox{\serif DU}(t)^{-1}dt,$ where $\hbox{\serif{U}}$ is the material stretch tensor. For example, when a material is compressed during pulsed-gradient diffusion encoding, the compression acts to increase the attenuation due to diffusion just as if a larger gradient were used. By using a simple gelatin phantom, the existence of this effect is demonstrated, and an effective method for its correction based on an MRI mapping of the material strain is presented. This correction is particularly relevant for inferring myofiber structure in the beating in vivo human heart, since the measurement of $\hbox{\serif{D}}$ is perturbed by the deformation of myocardium during the heart's contraction.

Journal Article↗
PubMed1998

Histological validation of myocardial microstructure obtained from diffusion tensor magnetic resonance imaging.

Diffusion tensor magnetic resonance imaging (MRI) is a possible new means of elucidating the anatomic structure of the myocardium. It enjoys several advantages over traditional histological approaches, including the ability to rapidly measure fiber organization in isolated, perfused, arrested hearts, thereby avoiding fixation and sectioning of artifacts. However, quantitative validation of this MRI method has been lacking. Here, fiber orientations estimated in the same locations in the same heart using both diffusion tensor MRI and histology are compared in a total of two perfused rabbit hearts. Fiber orientations were statistically similar for both methods and differed on average by 12 degrees at any single location. This is similar to the 10 degrees uncertainty in fiber orientation achieved with histology. In addition, imaging studies performed in a total of seven hearts support a level of organization beyond the myofiber, the recently described laminar organization of the ventricular myocardium.

Animals↗
PubMed2000

Outcome of patients with diffuse axonal injury: the significance and prognostic value of MRI in the acute phase.

BACKGROUND: To compare the magnetic resonance imaging (MRI) findings in the acute phase with outcome in patients with diffuse axonal injury (DAI). METHODS: A group of 33 patients with closed head injury and discrepancy between the apparently normal computed tomographic scan findings and their neurologic statuses were studied with MRI during the first 48 hours. Among them, 24 were found to suffer from DAI-type lesions. According to the Glasgow Coma Scale (GCS), 19 patients suffered from severe head injury (GCS score <8) and 5 patients had moderate head injury (GCS score of 9-12). Four MRI sequences in various planes were applied. Patients were divided into three groups, according to staging described in the literature. RESULTS: In five patients, MRI demonstrated nonhemorrhagic DAI lesions stage 1. In 11 patients, findings were consistent with DAI lesions stage 2, eight nonhemorrhagic and three hemorrhagic. Eight patients showed DAI lesions stage 3, six of which were nonhemorrhagic. CONCLUSIONS: MRI is more sensitive compared with computed tomography in the detection of traumatic brain lesions, especially the nonhemorrhagic DAI. The presence of hemorrhage in DAI-type lesions and the association with traumatic space-occupying lesions is a poor prognostic sign. Isolated nonhemorrhagic DAI-type lesions are not associated with poor clinical outcome.

Adolescent↗
PubMed2005

[Estimation of diffuse bone marrow infiltration of the spine in multiple myeloma: correlation of MRT with histological results].

PURPOSE: To determine the detection of diffuse bone marrow infiltration with MRI in comparison with histopathological findings. MATERIALS AND METHODS: MRI was performed on 45 patients with histologically proven multiple myeloma and on 30 healthy individuals. Three experienced radiologists read separately Tl-weighted SE sequences, STIR sequences and the combination of Tl-weighted SE and STIR sequences of the spine. Additionally, Tl-weighted SE sequences were obtained after gadolinium administration and the percentage increase in signal intensity was calculated. Bone marrow histology was used as gold standard for assessing the grade of infiltration. A dichotomous decision (infiltration yes/no) was made when assessing the MRI examinations. RESULTS: For the visual detection of diffuse infiltration, the best sensitivity was found with Tl-weighted SE sequences, achieving 71 % on average. The specificity was 89 %. The STIR sequences showed a sensitivity of 61 % and a specificity of 98 %, and the combination of Tl-weighted/STIR-sequences achieved a sensitivity of 65 % and a specificity of 94 %. In comparison with the histological findings, the sensitivity of the Tl-weighted sequences was 35 % for low-grade, 89 % for moderate and 100 % for high-grade infiltration. The application of contrast material with calculation of the percentage signal increase improved the detection by 7 %. CONCLUSION: The sensitivity of the visual detection of diffuse multiple myeloma with unenhanced MRI is limited for low-grade or moderate infiltration, whereas the sensitivity for high grade infiltration is reliable. The specificity is high and the diagnostic confidence improves after application of contrast material with calculation of the percentage increase in signal intensity.

Adult↗
PubMed1995

Meningeal biopsy in intracranial hypotension: meningeal enhancement on MRI.

Intracranial hypotension is a cause of diffuse enhancement of the pachymeninx with gadolinium, which often is associated with subdural fluid collections. We reviewed the results of meningeal biopsy in six patients with intracranial hypotension and diffuse pachymeningeal enhancement to correlate the MRI findings with histopathologic observations and to explain the abnormalities seen on MRI. Grossly, the dura mater was unremarkable in all patients, as were the leptomeninges, except for one patient with prolonged (18 months) intracranial hypotension in whom the arachnoid was thickened and opaque. Microscopically, the dura mater was entirely normal on its epidural aspect; however, a fairly thin zone of fibroblasts and thin-walled small blood vessels in an amorphous matrix was noted on the subdural aspect. In the patient with longstanding symptoms, diffuse benign arachnoidal cell proliferation was also noted, probably a reaction triggered by longstanding changes in the subdural area, as noted in the five other patients. There was no evidence of inflammation, infection, or metastatic neoplasia. These findings suggest that in intracranial hypotension, the dural-meningeal abnormalities probably represent reactive secondary phenomena, likely related to hydrostatic changes in the CSF, and not a primary meningeal process.

Aged↗