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Author(s): Dinesh Sonvane [1]; Rajeswaran Rangasami [1]; Anupama Chandrasekharan [1] Introduction T his pictorial essay aims at visualization of the normal fetal cranial nerves considering the earliest gestational age at [...], The importance of fetal magnetic resonance imaging (MRI) in the evaluation of the central nervous system (CNS) is well established. Fetal MRI is commonly performed at 20-24 weeks of gestational age. MRI has the advantage of allowing better visualization and characterization of normal brain structures. With improved MRI techniques, reduction of movement artifacts is possible. This review aims to provide a practical guide and reference for the normal appearance of the fetal cranial nerves. We did not find a similar article in our literature search. Keywords: Fetal, fetal MRI, magnetic resonance imaging (MRI)

Objective Gliomas are a devastating and heterogeneous group of primary brain tumors. Previously, the source of glioma was undetermined. Recent literature indicates that neural stem cells, or progenitors, are proposed to be the source of glioma. The prognosis of different types of gliomas differs due to their various biological tissue types. Besides the histological grade, the two useful immunohistochemistry markers that show the tumor's biological behavior are isocitrate dehydrogenase (IDH) labeling and the K i -67 labeling index. We sought to determine the magnetic resonance imaging (MRI) characteristics associated with IDH mutational status and ascertain whether MRI combined with IDH mutational status, can better predict the clinical outcomes of gliomas. Materials and Methods This period study was conducted in the Department of Radiology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India for 5 years (May 2016–May 2021). The study cohort included 30 patients diagnosed with gliomas who underwent preoperative MRI followed by surgical resection and histopathological examination. Preoperative MRI images were done to assess qualitative tumor characteristics such as location, margin of tumor, extent, cortical involvement, cystic component, mineralization or hemorrhage, and contrast enhancement. Discussion Differences in MRI features between IDH-mutant (MT) and IDH-wild-type (WT) groups were analyzed using the chi-square test for categorical variables and the Mann–Whitney U test for continuous variables. Statistical analysis was conducted using SPSS software. Results Among the 30 patients evaluated, 18 had IDH-WT and 12 had IDH-MT type gliomas. Male predominance (73.33%) was noted in our study. Brainstem location, indistinct borders (83.33%), less cortical involvement (72.22%), less cystic changes (88.89%), more area of necrotic component (44.44%), significantly increased choline/creatine (Cho/Cr) ratio, and choline/N-acetyl aspartate (Cho/NAA) ratio favors IDH-WT tumors. Positive T2-fluid-attenuated inversion recovery mismatch sign is more frequently seen in IDH-MT (7/12; 58.33%) tumors than in IDH-WT (4/18; 22.22%) tumors. Whereas well-defined contours (66.67%), more cortical involvement (83.33%), more cystic changes (58.33%), and less area of necrotic component favor IDH-MT type tumors. Conclusion MRI is a very promising and valuable tool for differentiating among glioma subtypes and predicting tumor-proliferative behavior in glioma cases. The combination of MRI characteristics with IDH mutation status enhances the predictive accuracy for clinical outcomes in glioma patients. This approach could potentially guide treatment planning and improve prognostic assessments. [ABSTRACT FROM AUTHOR]

Objectives: Our aim is to describe the utility of magnetic resonance imaging (MRI) in the evaluation of pathologies affecting large intracranial arteries. Materials and Methods: We performed a prospective and observational study from 2018 to 2020 using 1.5 T MRI. Our study included 75 patients who were referred for MRI brain with clinical features of stroke or having tumors/infection involving large intracranial arteries (vertebral, basilar, and internal carotid arteries) on initial MRI. Correlation of MRI diagnosis was done with final diagnosis. Results: Atherothrombosis was the most common pathology involving all the intracranial large arteries and was most commonly seen in elderly male patients. The second most common pathology involving the internal carotid, vertebral, and basilar arteries was tumors, dissection, and aneurysms, respectively. The most common artery involved by atherothrombosis, tumor, and infection/inflammation was internal carotid artery, whereas it was basilar artery and vertebral artery in cases of aneurysm and dissection, respectively. Conclusion: MRI is an extremely useful modality to study large intracranial arteries. It is useful to demonstrate the site of abnormality, vessel lumen and caliber, vessel wall changes, and perivascular areas. This can help in arriving at correct diagnosis and thereby guide appropriate timely management. [ABSTRACT FROM AUTHOR]

The aim of this article was to illustrate the major stages in cerebral cortical development, review the spectrum of cortical malformations based on the affected developmental stage, describe the characteristics of the major cortical malformations that may be diagnosed prenatally on fetal magnetic resonance imaging (MRI), and to understand the limitations of fetal MRI. Fetal MRI may show large dysmorphic cortex in hemimegalencephaly, cortical tubers, and subependymal nodules in tuberous sclerosis, smooth featureless cortex in classic lissencephaly, bumpy cortex in cobblestone lissencephaly, ectopic gray matter in heterotopia, excessive microgyri in polymicrogyria, and transmantle cerebral clefts in schizencephaly. We conclude that fetal MRI is of major value in diagnosing many of the cortical malformations including those suspected on prenatal ultrasound. However, fetal MRI is of limited sensitivity in detecting few cortical abnormalities like microdysgenesis especially in the second trimester, as gyration continues to evolve during late pregnancy and even after birth. [ABSTRACT FROM AUTHOR]

Objectives  The aim of the study is to assess the role of ultrafast (UF) magnetic resonance (MR) sequences in stroke imaging. Material and Methods  We prospectively studied 85 patients having clinical suspicion of stroke referred for MR imaging (MRI) during August 2016 to July 2018. These patients were subjected to both conventional and UF MRI sequences. The patients were divided into six categories based on the pathologies encountered. Further subclassification was done based on the size of the lesions as ≤10 mm and >10 mm as seen separately in both UF and conventional MR sequences. The number and visibility of these lesions on conventional and UF MRI were compared. The image quality of all the subjects was also compared based on a scale categorized into excellent, satisfactory, and poor. The findings on conventional and UF imaging sequences were correlated with the final clinical diagnosis arrived at the time of discharge. Results  In our study comprising 85 patients, 57 showed pathologies. The patients showing pathologies were assigned into the six categories as acute infarct (34 cases), acute hemorrhagic infarct (six cases), chronic infarct (17 cases), chronic hemorrhagic infarct (four cases), subacute infarct (three cases), and chronic hemorrhage (one case). The number of lesions seen on conventional and UF sequences were the same although there was a slight decrease in the size of the lesions on UF sequences as compared with conventional counterparts. The image quality using UF sequences was better in motion prone patients while conventional imaging showed better image quality in cooperative patients. Conclusion  In motion prone patients, UF sequences are a suitable alternative for conventional sequences as they help in arriving at the diagnosis in lesser time, with reasonably good image quality, and without motion artifacts. In cooperative stroke patients, it is better to use conventional MR sequences as the image quality is better. [ABSTRACT FROM AUTHOR]

Purpose: Preterm infants are at increased risk of adverse neurodevelopmental outcome (NDO). Cranial ultrasound has limited predictability. The purpose of the study is to evaluate whether magnetic resonance imaging (MRI) done at term equivalent age (TEA) predicts NDO at 18-22 months of corrected gestational age (CGA).Materials and methods: This cohort study of preterm infants born at ≤32 weeks of gestation and/or birth weight <1500 grams between April 2011 and August 2012 was conducted in a tertiary care institute in India. MRI done at TEA was reported using objective scoring. NDO at 18-22-month CGA was assessed using Bayley Scale of Infant Development (BSID) version III. Composite score (CS) < 85 in motor, language, or cognition domain was taken as adverse NDO. Association between individual MRI subscores and NDO was evaluated using multiple linear regressions by backward elimination method. Validity of MRI abnormality in predicting adverse NDO was assessed.Results: Out of 94 infants who had MRI at TEA, 56 (60%) underwent BSID III. Mean gestational age was 29.8 ± 2.1 weeks. Median CS of all domains was lower with higher total MRI score. Predictive accuracy for various subscores ranged from 55 to 73%. By multiple regression analysis, signal abnormality was associated with motor delay (β -8.4; p .02) and cystic white matter (WM) changes with motor delay (β -7.3; p .003) and cognitive delay (β -6.1; p .005).Conclusions: Although specificity and negative predictive value were moderate to high across all subscores in MRI to predict the NDO, the accuracy has been only low to moderate, which limits its use as sole predictor. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study is to compare the images obtained from standard ultrafast magnetic resonance (MR) imaging sequences with gradient (GRE) sequence images in identifying fetal intracranial hemorrhage (ICH). Materials and Methods: MR images of fetal brains with ICH done between October 2012 and September 2015 were reviewed. The images obtained from four ultrafast MR sequences– Turbo Fast Low Angle Shot (Turbo FLASH) T1-weighted images, Half Fourier Acquisition single-shot turbo spin echo (HASTE) T2-weighted images, b0 images of diffusion-weighted imaging (DWI) and b800 images of DWI were compared with images obtained from GRE sequence in depicting fetal ICH. Results: Out of the 212 fetuses during the study period, 15 fetuses had ICH. In the 15 fetuses with ICH as detected on GRE, Grade1 germinal matrix hemorrhage was seen in 5 fetuses, Grade 2 in 4 fetuses, Grade 3 in 3 fetuses, and Grade 4 in two fetuses. Subdural hemorrhage was seen in 1 fetus. In comparison to GRE sequence, b0 of DWI sequence was almost equal in the depiction of ICH. T2 HASTE sequence also delineated hemorrhage, although not as effectively as GRE and b0 images of images DWI. T1 Turbo FLASH and b800 images of DWI were less reliable in the depiction of fetal ICH but were useful in predicting the stage of hemorrhage. Conclusion: As compared to GRE sequence, b0 images of DWI followed by HASTE are the two preferred ultrafast sequences in the diagnosis of fetal ICH. [ABSTRACT FROM AUTHOR]

Viral encephalitis by definition is the result of human virus affecting the brain and sparing the meninges. The other nervous system manifestations are meningitis, meningoencephalitis, encephalomyelitis, and encephalomyeloradiculitis. Encephalitis can involve any age group from children to old people. The severity of the disease depends on the viral agent and the host immune system. The patient can present with fever, headache, seizure, neurological deficit, or altered sensorium. Laboratory investigations, imaging, and cerebrospinal fluid analysis are crucial in the diagnosis of encephalitis. Magnetic resonance imaging (MRI) findings may be nonspecific or specific and plays a major role in the diagnosis of encephalitis and predicting the possible cause. This pictorial essay reviews the MRI findings of common types of viral encephalitis. [ABSTRACT FROM AUTHOR]

Background & objectives: Renal artery stenosis (RAS) is an important cause of severe hypertension in patients with chronic kidney disease (CKD). It is important to detect RAS early as it can reverse hypertension and stop rapid deterioration of renal function. The potential drawbacks of various imaging modalities used to detect RAS including contrast-related adverse effects associated with diagnostic angiography have led to increasing interest in unenhanced magnetic resonance (MR) renal angiography. The aim of this study was to detect and grade RAS in patients with CKD and suspected renovascular hypertension using unenhanced MR angiography (UMRA) and to identify patients with significant RAS (>70%) who would subsequently require further investigation and revascularization. Methods: Thirty five CKD patients with suspected RAS were subjected to UMRA using non-contrast MR angiography of ArTery and VEins 3D True fast imaging with steady state precession technique over a three year period. Patients with RAS >70 per cent on UMRA were subjected to digital subtraction angiography (DSA) with intervention if indicated. Results: In all, 76 renal arteries were evaluated using UMRA in 35 patients, of which 18 arteries showed stenosis and 11 were haemodynamically significant (eight patients). Seven patients (10 renal arteries) underwent DSA. Interpretation & conclusions: An association between UMRA and DSA findings was obtained in six patients (nine renal arteries), and these patients were stented. Post-procedure follow up showed good improvement in blood pressure and renal function. UMRA was found to be a useful non-invasive imaging modality to detect RAS in CKD patients. It can identify patients who require further invasive angiography and revascularization. [ABSTRACT FROM AUTHOR]

Unilateral agenesis of internal carotid artery (ICA) with intercavernous anastomosis is a rare congenital anomaly. We present a case of a 25-year-old female with 2-month history of holocranial headache. Neurological examination was unremarkable. Magnetic resonance imaging (MRI) with magnetic resonance angiography (MRA) showed absence of left ICA with an abnormal intercavernous vessel in the sella. Computed tomography (CT) showed absence of the left carotid canal. Doppler ultrasonography (USG) showed high resistance flow in the left common carotid artery (CCA). Since no hemorrhage or aneurysm was seen, patient was managed conservatively and is on regular follow-up. Based on our knowledge, this is the first case to demonstrate the features of unilateral agenesis of ICA with intercavernous anastomosis in X-ray, Doppler USG, CT, and MRI scans of the brain. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the possible role of Magnetic Resonance (MR) signal intensity measurements in diagnosing Central Nervous System (CNS) anomalies antenatally. Methods: MR images of 110 fetal brains between 18 and 38 weeks were studied. Nine were excluded due to destroyed brain. 50 had CNS anomalies. 51 had normal CNS and were used as controls. Regions of interest (ROI) cursors were placed in Vitreous, cerebellar vermis, thalamus, frontal white matter, corona radiata, periventricular region and grey matter. The lateral ventricle diameters were also obtained. Signal intensity ratio (SIR) was calculated by the signal intensity of each of the above regions to that of the vitreous. SIR in controls were compared with fetuses having: (1) Hydrocephalus. (2) Arnold Chiari type-2 Malformation (ACM-2) (3) Non-progressive ventriculomegaly (4) Miscellaneous CNS anomalies. The correlation of the normalcy or abnormalcy of the brain was based on Clinical/Physical examination in 51, Ultrasound in 20, MRI in 2 and autopsy in 28. Results: In hydrocephalus and ACM-2, the SIR of vermis and periventricular region were higher than controls whereas in non-progressive ventriculomegaly and miscellaneous CNS anomalies there was no significant difference. Conclusion: Signal intensity measurements are useful to differentiate physiological and non-progressive ventriculomegaly from hydrocephalus and ACM-2. [ABSTRACT FROM AUTHOR]

Objective. To compare antenatal sonography and magnetic resonance (MR) imaging (MRI) in the diagnosis of fetal head and trunk anomalies. Methods. Forty pregnant women with fetal anomalies on ultrasound (US) examination underwent MRI. The MR examination was done by a radiologist who was provided with the US data. The MR images were then read by one of the two radiologists who were blinded to the US data. They were however told that the region of interest was (1) head-neck or (2) trunk or (3) both. Antenatal US and MRI findings were compared with postnatal diagnosis. Postnatal evaluation included plain radiograph, US, computed tomography, MRI, surgery, physical evaluation and autopsy. Results. Sixty anomalies were detected in the 40 women studied. This included 36 central nervous system (CNS), 7 thoracic, 7 gastrointestinal, 8 genitourinary and 2 face-neck anomalies. In the evaluation of CNS and thoracic anomalies, more number of confident diagnoses could be obtained by MRI when compared with that by US. In the detection of gastrointestinal and genitourinary anomalies, there was no significant difference between the two modalities. Conclusion. More number of confident diagnoses could be obtained by MRI when compared with that by US, in the evaluation of fetal CNS and thoracic anomalies. MRI can be used in complex fetal anomalies as a supplementary tool following US. [ABSTRACT FROM AUTHOR]

Congenital infiltrating lipomatosis of the face is a rare condition characterized by diffuse fatty infiltration of the facial soft tissues. There may be muscle involvement along with associated bony hyperplasia. It is a type of lipomatous tumor that is congenital in origin; it is rare and seen usually in childhood. We recently saw an 11-year-old girl with this condition. She presented with a swelling of the right side of the face that had been present since birth; there were typical findings on plain radiographs, CT, and MRI. The patient underwent cosmetic surgery. Histopathological examination showed mature adipocytes without any capsule. [ABSTRACT FROM AUTHOR]

Esophageal duplication cysts are classified as a subgroup of foregut duplication cysts. They are very rare and are predominantly detected in children. Antenatal detection is very rare. We report a case of an esophageal duplication cyst that was accurately identified antenatally by USG and MRI. [ABSTRACT FROM AUTHOR]