Imaging spectrum of posterior fossa anomalies on foetal magnetic resonance imaging with an algorithmic approach to diagnosis.

Posterior fossa abnormalities are one of the most common indications for performing foetal magnetic resonance imaging (FMRI). Ultrasonography is the initial imaging modality for assessment of foetal posterior fossa. Abnormal findings on ultrasonography warrant further evaluation with FMRI because it offers excellent soft-tissue contrast resolution and multiplanar capabilities. The neurological prognosis of different posterior fossa anomalies varies widely. FMRI plays a crucial role in confirming the diagnosis, assessing the prognosis, and counselling patients regarding continuation of pregnancy and possible post-natal developmental outcome. In this review we present the imaging spectrum of posterior fossa anomalies that readers can encounter in practice, highlight salient points in favour of each diagnosis, and provide a simplified algorithmic approach to reach the final diagnosis.

Unenhanced renal magnetic resonance angiography in patients with chronic kidney disease & suspected renovascular hypertension: Can it affect patient management?

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.

Histological characterization and development of mesial surface sulci in the human brain at 13-15 gestational weeks through high-resolution histology.

Cellular-level anatomical data from early fetal brain are sparse yet critical to the understanding of neurodevelopmental disorders. We characterize the organization of the human cerebral cortex between 13 and 15 gestational weeks using high-resolution whole-brain histological data sets complimented with multimodal imaging. We observed the heretofore underrecognized, reproducible presence of infolds on the mesial surface of the cerebral hemispheres. Of note at this stage, when most of the cerebrum is occupied by lateral ventricles and the corpus callosum is incompletely developed, we postulate that these mesial infolds represent the primordial stage of cingulate, callosal, and calcarine sulci, features of mesial cortical development. Our observations are based on the multimodal approach and further include histological three-dimensional reconstruction that highlights the importance of the plane of sectioning. We describe the laminar organization of the developing cortical mantle, including these infolds from the marginal to ventricular zone, with Nissl, hematoxylin and eosin, and glial fibrillary acidic protein (GFAP) immunohistochemistry. Despite the absence of major sulci on the dorsal surface, the boundaries among the orbital, frontal, parietal, and occipital cortex were very well demarcated, primarily by the cytoarchitecture differences in the organization of the subplate (SP) and intermediate zone (IZ) in these locations. The parietal region has the thickest cortical plate (CP), SP, and IZ, whereas the orbital region shows the thinnest CP and reveals an extra cell-sparse layer above the bilaminar SP. The subcortical structures show intensely GFAP-immunolabeled soma, absent in the cerebral mantle. Our findings establish a normative neurodevelopment baseline at the early stage.

Fascinating Case Presentation of Moyamoya Disease in Children and Adults.

Moyamoya disease is a rare idiopathic disease characterized by progressive stenosis and collateral development of the distal internal carotid arteries. It is mainly seen in East Asia and is the most common cause of stroke in Asian children. However, it is rare in the Indian subcontinent. We present three exciting cases of moyamoya disease with varied clinical presentations in one pediatric, one young adult, and one older patient.

Establishing and Comparing the Normal apparent Diffusion Coefficient Values of Fetal Organs and Placenta Using 1.5 Tesla and 3.0 T MRI at Various Gestational Age.

Background: Diffusion-weighted imaging (DWI) is the random Brownian motion of water molecules within a tissue voxel. The apparent diffusion coefficient (ADC) is a quantitative parameter calculated from the DWI that directly reflects the mobility of water molecules in biological tissues. The objective of this study was to establish and compare the normal reference ADC values of fetal organs and the placenta using 1.5 T and 3.0 T MRI at various gestational ages. Methods: This was a retrospective and prospective observational study. This study included one hundred and three (103) singleton pregnancies for each magnetic field strength. Diffusion-weighted imaging was performed using single-shot spin-echo-planar imaging (EPI) in the axial plane of the fetal head-trunk with a slice thickness of 4mm and diffusion gradient values of b = 0 and b = 700-800 s/mm2. Results: The mean ADC values of cerebral WM areas were significantly higher than the deep grey areas in the brain. The white-matter regions, lung, and placenta showed a positive and significant correlation with increasing gestational age in both field strengths. A statistically weak negative correlation was observed between increasing gestational age and ADC measurements obtained in the thalamus, cerebellum, pons, and kidney. Conclusion: This study gives the reference values for both 1.5T and 3T MRI of vital organs. The current study shows that diffusion-weighted MRI can offer a promising technique to evaluate the structural development of fetal organs and can potentially act as a biomarker for predicting the functionality of the fetal organs in abnormalities.

Magnetic resonance imaging in the evaluation of the pathologies affecting large intracranial arteries.

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.

A Radiological Review of the Unusual Contents of Inguinal Region.

Background The inguinal region is an area of complex anatomy that could contain diverse uncommon contents in routine clinical practice. Although inguinal hernia repair is one of the commonest surgeries done routinely, thorough preoperative imaging has a significant impact on the outcome of the surgery, by revealing the presence of unusual contents in the inguinal region. Aim The aim of this article is to review the differential diagnosis of the uncommon inguinal pathologies, which can simulate an inguinal hernia, to determine, and to simplify the treatment approach. Conclusions A profound understanding of the imaging characteristics of uncommon inguinal pathologies is crucial for both the radiologists (to prevent misdiagnosis) and the treating physicians (to avoid surgical complications) and ensure optimal management.

Fetal Pontine Tegmental Cap Dysplasia- A Case Report.

Pontine tegmental cap dysplasia (PTCD) is a very rare hindbrain malformation recently described and the affected children show a bad prognosis. We present this case to increase the awareness of this rare condition and to highlight the importance of early prenatal diagnosis. A 25 years old female with 22 weeks gestation was referred after sonography for fetal magnetic resonance imaging (MRI) in the evaluation of cerebellar hypoplasia. Prenatal MRI confirmed cerebellar hypoplasia. Follow up postnatal MRI showed flattening of the ventral pons, beak-like tissue in the posterosuperior pons suggesting the diagnosis of PTCD. In retrospect the fetal MR images revealed features consistent with PTCD. To the best of our knowledge, this is the fifth prenatal case and with the earliest gestational age of 22 weeks.

Effect of recanalization on clinical outcomes in patients with cerebral venous thrombosis - An ambispective study.

PURPOSE: Achieving complete recanalization has possible but unproven benefits in cerebral venous/sinus thrombosis (CVST). We reported a cohort of patients with CVST and assessed the factors associated with recanalization and its effect on outcomes. METHODS: We included 123 patients with CVST in this single-center, ambispective, observational study from October 2018 to November 2019. We noted their demographic, clinical, and radiological features, modified Rankin scale (mRS), recanalization status, and the presence of any recurrences while having periodic follow-ups every three months for one year or until complete recanalization, whichever was earlier. RESULTS: Out of the 123 patients enrolled, we completed the etiological evaluation in 122 and assessed the outcome at discharge in 120. One (0.8%) patient went against medical advice, 2 (1.6%) died in the hospital, and 8 (6.5%) were lost to follow-up at various time points. The majority of the patients were males (75 [60.98%]). Thrombophilia (71 [58.2%]) and hematological conditions (51[41.8%]) were the predominant risk factors for CVST. The majority (107 [95.5%] at three months) of the patients had an mRS of 0-1. Eighty-one (67.5%) and 26 (21.7%) patients attained complete and partial recanalization at their last follow-up, respectively. Involvement of transverse and sigmoid sinus was an independent predictor of poor recanalization (Odds Ratio [OR] {Confidence Intervals [CI]} - 0.2 (0.04-0.7); p = 0.01). Moreover, failure to achieve at least partial recanalization (OR [CI] - 94 [6.8-1296]; p = 0.01) and undergoing a decompression craniectomy (OR [CI] - 26.4 [1.2-582]) were the only factors that independently predicted poor functional outcomes in our cohort. CONCLUSION: Most of the patients with CVST had favorable outcomes. Recanalization was a strong predictor of good functional outcomes. Therefore, recanalization status should be considered while deciding when to stop the anticoagulation. However, we found no differences in the outcomes between those who achieved partial and complete recanalization.

Sciatic Nerve Hematoma - Case Report.

Hemorrhagic neuropathy is an extremely rare condition. This condition refers to bleed into or around a peripheral nerve, causing either an extra neural or an intraneural hematoma. When they do occur, it is usually due to iatrogenic/inherited coagulopathies or as a consequence of injections targeting nerves. We present a case of sciatic nerve palsy developed secondary to anticoagulant therapy (Warfarin). MRI imaging showed features of sciatic nerve hematoma following which warfarin was withdrawn. The patient showed symptomatic improvement and a follow up ultrasound of left thigh showed resolution of hematoma with normal sciatic nerve diameter. To the best of our knowledge there is limited available literature regarding nerve hematomas secondary to anticoagulation therapy. This complication should be promptly recognized and immediate steps should take place because of the favorable results of the early treatment.

Magnetic Resonance Imaging Findings in Fetal Corpus Callosal Developmental Abnormalities: A Pictorial Essay.

The corpus callosum is the principal supratentorial cerebral commissure, which connects the two cerebral hemispheres in the midline. It is divided into rostrum, genu, body, and splenium. Affected patients may develop mental retardation, dysmorphic features, spasticity, ataxia, or epilepsy. Corpus callosal abnormalities may be isolated or be associated with other anomalies such as sulcal abnormality, ventriculomegaly, cerebellar hypoplasia or cerebellar vermian hypoplasia. Magnetic resonance imaging (MRI) plays a major role in the diagnosis of fetal corpus callosal developmental abnormalities when they are suspected on sonography. This pictorial essay shows the MRI findings in fetal corpus callosal developmental abnormalities in a very systematic manner.

Role of Ultrafast MR Imaging in Stroke Patients.

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.

Magnetic Resonance Imaging Findings in Viral Encephalitis: A Pictorial Essay.

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.