OUR PUBLICATIONS

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Varadharajan S. "ASAP" in Acute Stroke Imaging - Need to Simplify and Standardize Reporting Formats in an Emergency. Neurol India 2022;70:2185-6

DOI:  https://www.neurologyindia.com/text.asp?2022/70/5/2185/359294

Acute Stroke is managed by multidisciplinary team and treatment decisions are predominantly based on imaging studies and has become increasingly complex incorporating various modalities ranging from plain CT brain, vascular imaging including multiphasic studies to complex perfusion studies, especially for deciding candidates for endovascular treatment as well as for those with delayed presentation.[1],[2],[6] Simplified and structured imaging formats are needed to avoid confusion and treatment delay as well as for medicolegal aspect of reporting scans immediately. Acute Stroke Acquisition protocols (ASAP) aims to simplify acute stroke imaging depending on local logistics and patient presentation

October 2022 Journal of Stroke Medicine 

DOI: 10.1177/25166085221122393

Recent studies have shown that diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) MRI (DWI-FLAIR) mismatch is useful for thrombolytic treatment decisions in acute ischemic stroke. However, the role of partial mismatch in strategic locations among patients with evolving stroke has not been described before. Partial imaging mismatch involving strategic locations might indicate reversible ischemia, enabling thrombolysis even in those patients presenting in the extended time windows. In this report, we describe the partial strategic concept of DWI-FLAIR mismatch with case examples

September 2022The Neuroradiology Journal 

DOI: 10.1177/19714009221130488

Neonatal strokes constitute a major cause of pediatric mortality and morbidity. Neuroimaging helps in its diagnosis as well as prognostication. However, advanced imaging, including magnetic resonance imaging (MRI), carries multiple challenges. Limited data exists in the literature on imaging-based predictors of neurological outcomes in neonatal stroke in the Indian population. In this study, we reviewed our available data on neonatal stroke patients between 2015 and 2020 for clinico-radiological patterns. During this period, 17 neonatal strokes were admitted and the majority were term births with a slight male preponderance. Seizures and encephalopathy were the most common presentation. Multiple maternal risk factors such as gestational diabetes, meconium-stained liquor, APLA syndrome, fever, deranged coagulation profile, oligohydramnios, cord prolapse, and non-progressive labor were seen. Cardiac abnormalities were seen in only less than half of these patients with the most common finding being atrial septal defects (ASD). Transcranial ultrasound was performed in eight neonates and the pick-up rate of ultrasound was poor. MR imaging showed large infarcts in 11 patients. The MCA territory was most commonly involved. Interestingly, five neonates had venous thrombosis with three showing it in addition to arterial thrombosis. Associated ictal, as well as Wallerian changes, were noted in 10. Although large territorial infarcts were the most common pattern, non-contrast MR angiography did not show major vessel occlusion in these cases. Outcomes were fairly good and only three patients had a residual motor deficit at 1 year. No recurrence of stroke was seen in any of the neonates.

13th World Stroke Congress 2021

April 2021 Journal of Stroke Medicine 4(1):251660852110102

DOI:  10.1177/25166085211010229

Background 

Arterial spin labelling (ASL) is a noncontrast, magnetic resonance perfusion technique which can provide information about the parenchymal perfusion status and collaterals in acute stroke. Its role in the setting of large vessel occlusion (LVO) is underutilized due to the limited availability of magnetic resonance imaging (MRI) in the emergency settings. However, it might serve as an useful adjunct to other perfusion modalities in future. Objective To study ASL perfusion patterns in anterior circulation LVO stroke and evaluate the presence of arterial transit artefacts (ATA) as a surrogate marker of collaterals. 

Methods 

We performed a retrospective analysis of our mechanical thrombectomy database over the last 2 years for acute stroke cases in which ASL perfusion as part of MRI was performed. ASL perfusion patterns in acute LVO stroke were reviewed, with respect to presence of ATA and diffusion-weighted imaging (DWI)-ASL mismatch. Inter-rater reliability was analyzed between 2 readers of varying experience. Baseline variables were analyzed between those with and without ATA. 

Results 

Out of 95 patients, 78 had anterior circulation occlusions, among which 27 had ASL. Type I (with ATAs) was seen in 11 patients and all of these had DWI mismatch. Type II (without ATAs) was seen in 16 patients. Of these, 15 had mismatch with DWI and only 1 had no mismatch. Inter-rater reliability for the detection of ATA on ASL was substantial (Cohen’s k—0.64). No statistical significance was noted between ATA and clinical outcomes. 

Conclusion 

ASL patterns vary amongst patients with LVO stroke and can be classified based on the presence of ATA since resulting DWI mismatch actually indicates a pseudo-perfusion deficit.

August 2022

Journal of Clinical Interventional Radiology ISVIR 06(02)

DOI: 10.1055/s-0041-1736085

Background: Imaging of acute stroke patients in emergency settings is critical for treatment decisions. Most commonly, CT with CTA is used worldwide for acute stroke. However, MRI may be advantageous in certain settings. With advancements in endovascular clot retrieval techniques, there is a need to identify and use the best possible imaging for the diagnosis and outcome prediction of hyperacute stroke. 

Methods: This mixed retrospective and prospective observational study was conducted over 2 years in patients who underwent reperfusion therapies. Patients were included in this study if they had a baseline as well as follow-up noncontrast CT and diffusion-weighted imaging (DWI) MRI. We compared them for estimating final infarct size and outcomes after reperfusion therapy. Results: A total of 86 patients were included in the study. Baseline DWI found new infarcts in 33 patients compared to baseline CT. Sensitivity and specificity of CT and DWI in predicting the final infarct size was 75.3% and 76.9% and 97.2% and 92.3%, respectively. A positive correlation of 51.2% and 84.4% was noted between b-CT Alberta stroke programme early CT score (ASPECTS) and b-DWI with 72 hours DWI ASPECTS, respectively (p < 0.001). The positive predictive value of CT was 94.8% and DWI was 98.6%. None of the patients had reversible hyperintensities in the follow-up DWI. 

Conclusion: MRI is more sensitive and specific than noncontrast CT in predicting final infarct volume. It predicts final outcomes better and could be an alternative if available in acute stroke settings.

March 2021Conference: Indian National Stroke Conference 2021

The COVID-19 pandemic had brought unique and difficulties challenges to emergency health care services worldwide. Indian scenario was no different and public fear of the pandemic combined with strict travel restrictions enforced during the initial lockdown phases drastically affected number of patients seeking emergency medical attention. Stroke is an acute neurological emergency which needs immediate attention to prevent significant morbidity and mortality. Various studies in India and in different other parts of the world have shown that there was a decline in stroke related admissions during the pandemic. Lack of stroke awareness, lack of transportation and fear of covid were few of stated reasons for decline and delay in stroke admissions. We wanted to evaluate the impact of COVID-19 and the lockdown measures on our acute stroke care services in a tertiary care hospital

July 2021

DOI:  10.4103/0028-3886.325300

Patients presenting with stroke are:

1. Referred pain of cardiogenic/aortic origin at onset including chest, neck, jaw, or tooth pain.
2. Multi territorial juxta cortical infarcts in MRI with involvement of watershed regions.
3. Intimal flap and eccentric wall thickening (intramural hematoma) on vascular imaging.
4. Progressive infarcts on follow up imaging with deteriorating clinical course.

September 2022

DOI: 10.26044/ecr2022/C-19023

Conference: European Congress of Radiology 2022

A brief overview of our epilepsy protocol and review its sequences 

The spectrum of imaging findings in our acute seizure patients 

Differentiation of seizure-induced changes on imaging from underlying causes 

Diagnostic algorithm for seizure imaging using case-based examples

June 2020

Conference: European Congress of Radiology 2020

DOI-Link:

https://dx.doi.org/10.26044/ecr2020/C-10175

ASL is a non-invasive MRI technique of perfusion using labelled RBCs as tracers. It can be applied in both 1.5 and 3T scanners alike using different labelling techniques (pulsed ASL and Pseudo-continuous ASL)

We explore the role of ASL in routine neuroimaging protocols (in both elective and emergency indications) and highlight its usefulness while raising red flags about its pitfalls, technical limitations as well as clinical caveats.

March 2020

Conference: AAFITN 2020

Conventional techniques of vascular imaging (CTA, MRA and DSA) reveal abnormalities of the lumen of the vessel. However, most vascular pathologies show similar lumenographic findings. Intracranial high resolution vessel wall imaging (vWI) has emerged as a promising tool which can directly visualize and characterize the disease of the vessel wall. We explore the role of vessel wall imaging and the additional yield it provides in evaluating intracranial neurovascular diseases.