Advanced diffusion imaging reveals microstructural characteristics of primary CNS lymphoma, allowing differentiation from glioblastoma.

Background: Primary CNS lymphoma (PCNSL) and glioblastoma (GBM) both represent frequent intracranial malignancies with differing clinical management. However, distinguishing PCNSL from GBM with conventional MRI can be challenging when atypical imaging features are present. We employed advanced dMRI for noninvasive characterization of the microstructure of PCNSL and differentiation from GBM as the most frequent primary brain malignancy. Methods: Multiple dMRI metrics including Diffusion Tensor Imaging, Neurite Orientation Dispersion and Density Imaging, and Diffusion Microstructure Imaging were extracted from the contrast-enhancing tumor component in 10 PCNSL and 10 age-matched GBM on 3T MRI. Imaging findings were correlated with cell density and axonal markers obtained from histopathology. Results: We found significantly increased intra-axonal volume fractions (V-intra and intracellular volume fraction) and microFA in PCNSL compared to GBM (all P < .001). In contrast, mean diffusivity (MD), axial diffusivity (aD), and microADC (all P < .001), and also free water fractions (V-CSF and V-ISO) were significantly lower in PCNSL (all P < .01). Receiver-operating characteristic analysis revealed high predictive values regarding the presence of a PCNSL for MD, aD, microADC, V-intra, ICVF, microFA, V-CSF, and V-ISO (area under the curve [AUC] in all >0.840, highest for MD and ICVF with an AUC of 0.960). Comparative histopathology between PCNSL and GBM revealed a significantly increased cell density in PCNSL and the presence of axonal remnants in a higher proportion of samples. Conclusions: Advanced diffusion imaging enables the characterization of the microstructure of PCNSL and reliably distinguishes PCNSL from GBM. Both imaging and histopathology revealed a relatively increased cell density and a preserved axonal microstructure in PCNSL.

Mesoscopic Assessment of Microstructure in Glioblastomas and Metastases by Merging Advanced Diffusion Imaging with Immunohistopathology.

BACKGROUND AND PURPOSE: Glioblastomas and metastases are the most common malignant intra-axial brain tumors in adults and can be difficult to distinguish on conventional MR imaging due to similar imaging features. We used advanced diffusion techniques and structural histopathology to distinguish these tumor entities on the basis of microstructural axonal and fibrillar signatures in the contrast-enhancing tumor component. MATERIALS AND METHODS: Contrast-enhancing tumor components were analyzed in 22 glioblastomas and 21 brain metastases on 3T MR imaging using DTI-fractional anisotropy, neurite orientation dispersion and density imaging-orientation dispersion, and diffusion microstructural imaging-micro-fractional anisotropy. Available histopathologic specimens (10 glioblastomas and 9 metastases) were assessed for the presence of axonal structures and scored using 4-level scales for Bielschowsky staining (0: no axonal structures, 1: minimal axonal fragments preserved, 2: decreased axonal density, 3: no axonal loss) and glial fibrillary acid protein expression (0: no glial fibrillary acid protein positivity, 1: limited expression, 2: equivalent to surrounding parenchyma, 3: increased expression). RESULTS: When we compared glioblastomas and metastases, fractional anisotropy was significantly increased and orientation dispersion was decreased in glioblastomas (each P < .001), with a significant shift toward increased glial fibrillary acid protein and Bielschowsky scores. Positive associations of fractional anisotropy and negative associations of orientation dispersion with glial fibrillary acid protein and Bielschowsky scores were revealed, whereas no association between micro-fractional anisotropy with glial fibrillary acid protein and Bielschowsky scores was detected. Receiver operating characteristic curves revealed high predictive values of both fractional anisotropy (area under the curve = 0.8463) and orientation dispersion (area under the curve = 0.8398) regarding the presence of a glioblastoma. CONCLUSIONS: Diffusion imaging fractional anisotropy and orientation dispersion metrics correlated with histopathologic markers of directionality and may serve as imaging biomarkers in contrast-enhancing tumor components.

The value of qualitative and quantitative assessment of lesion to cerebral cortex signal ratio on double inversion recovery sequence in the differentiation of demyelinating plaques from non-specific T2 hyperintensities.

OBJECTIVES: To assess the usefulness of the visual assessment and to determine diagnostic value of the lesion-to-cerebral cortex signal ratio (LCSR) measurement in the differentiation of demyelinating plaques and non-specific T2 hyperintensities on double inversion recovery (DIR) sequence. MATERIAL AND METHODS: DIR and fluid-attenuated inversion recovery (FLAIR) sequences of 25 clinically diagnosed multiple sclerosis (MS) patients and 25 non-MS patients with non-specific T2-hyperintense lesions were evaluated visually and LCSRs were measured by two observers independently. RESULTS: On DIR sequence, the calculated mean LCSR ± SD for demyelinating plaques and non-specific T2-hyperintense lesions were 1.60 ± 0.26 and 0.75 ± 0.19 for observer1, and 1.61 ± 0.27 and 0.74 ± 0.19 for observer2. LCSRs of demyelinating plaques were significantly higher than other non-specific T2-hyperintense lesions on DIR sequence. By using the visual assessment demyelinating plaques were differentiated from non-specific T2-hyperintensities with 92.8 % sensitivity, 97.5 % specificity and 95.1 % accuracy for observer1 and 92.8 % sensitivity, 95 % specificity and 93.9 % accuracy for observer2. CONCLUSION: Visual assessment and LCSR measurement on DIR sequence seems to be useful for differentiating demyelinating MS plaques from supratentorial non-specific T2 hyperintensities. This feature can be used for diagnosis of MS particularly in patients with only supratentorial T2-hyperintense lesions who are categorized as radiologically possible MS. KEY POINTS: • Demyelinating plaques and non-specific T2-hyperintensities have different SI on DIR images. • These differences can be assessed by LCSR measurement or visual assessment. • There is an excellent inter-observer agreement for both methods. • This feature can be used in radiologically possible MS cases.

Brain herniations into the dural venous sinus or calvarium: MRI findings, possible causes and clinical significance.

OBJECTIVES: To determine frequency, imaging features and clinical significance of herniations of brain parenchyma into dural venous sinuses (DVS) and/or calvarium found on MRI. METHODS: A total of 6160 brain MRI examinations containing at least one high-resolution T1- or T2-weighted sequence were retrospectively evaluated to determine the presence of incidental brain herniations into the DVS or calvarium. MRI sequences available for review were evaluated according to their capability to demonstrate these herniations. Patients' symptoms and clinical findings were recorded. RESULTS: Twenty-one (0.32 %) brain parenchyma herniations into the DVS (n = 18) or calvarium (n = 3) in 20 patients were detected. The most common locations of the herniations were the transverse sinuses (n = 13) and those involving inferior gyrus of the temporal lobe (n = 9). High-resolution T1- and T2-weighted sequences were equally useful in the detection of these brain herniations. According to clinical symptoms, brain herniations were considered to be incidental but headaches were present in nine patients. CONCLUSION: Brain herniations with surrounding cerebrospinal fluid (CSF) into the DVS and/or calvarium are incidental findings and not proven to be associated with any symptoms. Although rare, these herniations are more common than previously recognized and should not be confused with arachnoid granulations, clots or tumours. KEY POINTS: • Brain herniations into the DVS are more common than previously assumed. • The most frequent locations are the transverse sinus. • These herniations are incidental findings. • The relationship between brain herniation into DVS and headache is uncertain. • High-resolution MR sequences are most useful in detection of brain herniations.

Malformations of cortical development: 3T magnetic resonance imaging features.

Malformation of cortical development (MCD) is a term representing an inhomogeneous group of central nervous system abnormalities, referring particularly to embriyological aspect as a consequence of any of the three developmental stages, i.e., cell proliferation, cell migration and cortical organization. These include cotical dysgenesis, microcephaly, polymicrogyria, schizencephaly, lissencephaly, hemimegalencephaly, heterotopia and focal cortical dysplasia. Since magnetic resonance imaging is the modality of choice that best identifies the structural anomalies of the brain cortex, we aimed to provide a mini review of MCD by using 3T magnetic resonance scanner images.

Split-bolus MR urography: synchronous visualization of obstructing vessels and collecting system in children.

Several vascular abnormalities related with urinary system such as crossing accessory renal vessels, retroiliac ureters, retrocaval ureters, posterior nutcracker syndrome, and ovarian vein syndrome may be responsible for urinary collecting system obstruction. Split-bolus magnetic resonance urography (MRU) using contrast material as two separate bolus injections provides superior demonstration of the collecting system and obstructing vascular anomalies simultaneously and enables accurate preoperative radiologic diagnosis. In this pictorial review we aimed to outline the split-bolus MRU technique in children, list the coexisting congenital collecting system and vascular abnormalities, and exhibit the split-bolus MRU appearances of concurrent urinary collecting system and vascular abnormalities.

MRI diagnosis of dural sinus - Cortical venous thrombosis: Immediate post-contrast 3D GRE T1-weighted imaging versus unenhanced MR venography and conventional MR sequences.

OBJECTIVE: Primary aim is to compare the diagnostic value of contrast-enhanced 3D GRE T1-weighted sequences with unenhanced MR venography and conventional magnetic resonance imaging (MRI), in detection of dural venous sinus (DVS) and cortical venous thrombosis; secondary aim is to determine the relationship between DVS thrombosis/site and gender, age, infarction or hemorrhage. METHODS: We retrospectively reviewed conventional MR images, unenhanced MR venography and immediate post-contrast 3D GRE T1-weighted MR images in 30 patients (17 male and 13 female, 21-70 years old, mean age 40.1) with clinically suspected DVS thrombosis. MR examinations had been performed with 1.5T or 3T MR Scanners. DVSs were evaluated in 10 sub-segments, including cortical veins. Each set of MR images were examined separately, blinded to the final diagnosis. Associated findings were also noted and sensitivity, specificity and accuracy of each MRI technique were calculated. RESULTS: Final diagnosis of cortical venous and/or dural sinus thrombosis was established in 24 (80%) of 30 cases and 67 (22.3%) out of 300 segments. For detection of the thrombotic segment, sensitivity, specificity, and accuracy were 83.6%, 95.3%, and 92.7% by conventional MR sequences, 89.6%, 91.8%, and 91.3% by unenhanced MR venography, and 92.5%, 100%, and 98.3% by contrast-enhanced 3D GRE T1-weighted sequence, respectively. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis, while gender and age had no significant relation with DVS thrombosis or its site. Conventional MR sequences and unenhanced MR venography were helpful due to additional information they provided in some cases with isolated cortical venous thrombosis, with hyperintense thrombus material and with associated hemorrhage or infarction. CONCLUSION: Contrast-enhanced 3D GRE T1-weighted MRI is the most accurate imaging method for the detection of DVS and/or cortical venous thrombosis. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis.

Measures of ventricles and evans' index: from neonate to adolescent.

Ventricle sizes are important for the early diagnosis of hydrocephalus or for follow-up after ventriculostomy. Diameters of ventricles may change, especially in childhood. This study aims to provide normative data about ventricle diameters. Among 14,854 cranial MRI performed between 2011 and 2013, 2,755 images of Turkish children aged 0-18 years were obtained. After exclusions, 517 images were left. Four radiologists were trained by a pediatric radiologist. Twenty images were assessed by all radiologists for a pilot study to see that there was no interobserver variation. There were 10-22 children in each age group. The maximum width of the third ventricle was 5.54 ± 1.29 mm in males in age group 1 and 4.98 ± 1.08 mm in females in age group 2. The Evans' index was <0.3 and consistent with the literature. The third ventricle/basilar artery width ratio was found to be >1 and <2 in all age groups and both gender groups. Our study showed the ventricle size data of children in various age groups from newborn to adolescent. The ventricle volume/cerebral parenchyma ratio seems to decrease with age. We think that these data can be applied in clinical practice, especially for the early diagnosis of hydrocephalus.

Prevalence of dual left anterior descending artery variations in CT angiography.

PURPOSE: We aimed to evaluate the frequency and features of dual left anterior descending artery (LAD) variants using computed tomography (CT) angiography. METHODS: A total of 1337 consecutive coronary CT angiography examinations performed between April 2010 and December 2013 were retrospectively evaluated for the presence of dual LAD. CT examinations were performed with either 64- or 320-row multidetector CT scanners. All CT angiography images were evaluated for the presence and morphologic features of dual LAD subtypes. RESULTS: Fifty-six dual LAD variations (4%) were identified in this study population. Type 1 was the most common type of dual LAD (n=48), while Type 3 (n=3) and Type 4 (n=2) were infrequent and Type 2 was not detected. Additionally, we detected previously unclassified dual LAD variations in three cases. CONCLUSION: Dual LAD may be a relatively more common variant than described in the medical literature, which is mostly based on catheter angiography studies. Coronary CT angiography seems markedly efficacious for detecting and documenting the anatomical details of dual LAD subtypes, as well as showing other associated cardiocoronary anomalies.

Measures of pituitary gland and stalk: from neonate to adolescence.

OBJECTIVE: The aim of this study is to provide normative data about pituitary diameters in a pediatric population. Pituitary imaging is important for the evaluation of the hypothalamo-pituitary axis defect. However, data about normal pituitary gland diameters and stalk are limited, especially in children. Structure and the measurements of pituitary gland and pituitary stalk may change due to infection, inflammation, or neoplasia. METHODS: Among 14,854 cranial/pituitary gland magnetic resonance imaging scans performed from 2011 to 2013, 2755 images of Turkish children aged between 0 and 18 were acquired. After exclusions, 517 images were left. Four radiologists were educated by an experienced pediatric radiologist for the measurement and assessment of the pituitary gland and pituitary stalk. Twenty cases were measured by all radiologists for a pilot study and there was no interobserver variability. RESULTS: There were 10-22 children in each age group. The maximum median height of the pituitary gland was 8.48±1.08 and 6.19±0.88 mm for girls and boys, respectively. Volumes were also correlated with gender similar to height. Minimum median height was 3.91±0.75 mm for girls and 3.81±0.68 mm for boys. The maximum and minimum pituitary stalk basilar artery ratios for girls were 0.73±0.12 and 0.59±0.10 mm. The ratios for boys were 0.70±0.12 and 0.56±0.11 mm. CONCLUSION: Our study demonstrated the pituitary gland and stalk size data of children in various age groups from newborn to adolescent. It is thought that these data can be applied in clinical practice. Future prospective follow-up studies with larger samples, which correlate the structural findings with the clinical and laboratory results are awaited.