"Trapped labelled spins"-related signal on arterial spin labelling in the assessment of flow-diverted aneurysms: preliminary experience.

PURPOSE: To investigate ASL-MRI features of flow-diverted aneurysms, review their haemodynamic surrogates, and discuss their pertinent clinical implications. METHODS: Retrospective single institutional analysis was performed on the clinical and imaging data of patients who underwent digital subtraction angiography (DSA) and ASL-MRI after endovascular flow diversion for cerebral aneurysms. Pseudo-continuous ASL-MRI was performed with post-label delays of 1525-1800 ms. Intra-aneurysmal "trapped labelled spins" (TLS)-related hypersignal, as seen on cerebral blood flow (CBF)-weighted maps of ASL-MRI, was investigated. Intermodality equivalence with DSA [O'Kelly-Marotta (OKM) grading for occlusion], 3D-TOF-MRA, and 3D spin-echo T1-weighted ("black-blood") images was assessed. RESULTS: Ten cases were included. "TLS" signal was demonstrable in 7/8 (87.5%) of the DSA-visible flow-diverted aneurysms (OKM grade B3, n = 6; OKM grade A3, n = 2). No TLS was seen in both OKM-D (excluded) aneurysms. TLS was not visualised in an OKM-B3 aneurysm with < 3 mm opacifying remnant. 3D-TOF-MRA and ASL-MRI were discordant at 5 instances (45.4%; TOF-MRA false negative, n = 4; false positive, n = 1). Loss of flow void on black-blood images corresponded to the absence of TLS and vice versa in all cases but one. CONCLUSION: "Trapped labelled spins"-related signal on ASL-MRI occurs in patent large aneurysms that have undergone successful endovascular flow diversion. This phenomenon likely represents an interplay of a multitude of haemodynamic factors including decelerated intra-aneurysmal inflow and outflow restriction. Serial intra-saccular TLS signal changes may hold diagnostic value, including contexts where 3D-TOF-MRA interpretation becomes dubious. "Trapped labelled spins"-related signal as a non-invasive proxy marker of aneurysm patency can possibly obviate unnecessary DSA.

MRI Spectrum of Toxic Encephalopathy-An Institutional Experience.

Background: There are numerous toxins that affect our nervous system, both central and peripheral. Innumerable differentials exist in patients of acute encephalopathy and the list can be narrowed down with appropriate imaging. Specific neuroradiological features point to a particular diagnosis in a substantial number of cases. Objective: Through this study, we aimed to demonstrate the varied imaging findings of toxic encephalopathy on MRI encountered at our institute. Material and Methods: A retrospective analysis of the patients clinically diagnosed as toxic encephalopathy and referred for imaging between March 2015 and December 2019 was done. A total of 25 patients were included. Patient records were reviewed for clinical details, laboratory investigations, and treatment; the institute Picture Archiving and Communication System provided the imaging findings. Results: Patients presenting were aged between 22 and 55 years (mean-34.3 years). Four patients (16%) presented with imaging findings characteristic of Marchiafava-Bignami disease and six patients (24%) had MRI findings of Wernicke encephalopathy. Three patients (12%) had methanol poisoning sequelae while imaging findings of nitroimidazole drug toxicity were observed in another three patients (12%). Two patients (8%) each of carbon monoxide poisoning and lead toxicity were seen. We had one patient (4%) each of isoniazid, methyl iodide, dextropropoxyphene toxicity, chronic toluene abuse, and hyperglycemia-induced hemiballismus-hemichorea. Conclusion: Our study illustrates the amalgamated spectrum of MRI appearances in various subgroups of toxic encephalopathies. Imaging substantiated by relevant history and clinical manifestations can accurately diagnose the possible causative agent in the majority of the cases.

"Neuroimaging in ethambutol induced optic neuropathy: MRI in time can save the vision".

Ethambutol is an integral part of Antitubercular therapy (ATT) and is often associated with optic neuropathy, However, neuroimaging of ethambutol induced optic neuropathy has been sparsely reported in the literature. We describe the case of a 45-year male patient, diagnosed as Tuberculous spondylodiscitis and was on ATT. Four months after ATT initiation, he presented with visual blurring in both the eyes with bitemporal hemianopia and central scotomas. Visual evoked potential (VEP) revealed prolonged latencies in N75 and P100 waveforms bilaterally. Magnetic Resonance Imaging (MRI) showed optic chiasma and bilateral optic tract hyperintensities on 3D Fluid Attenuated Inversion Recovery (FLAIR) and 3D Double Inversion Recovery (DIR) sequences. Ethambutol was discontinued immediately. On follow-up after 8 weeks, visual acuity reversed back to normal in both eyes.

Tumefactive Demyelination versus Primary Central Nervous System Lymphoma on 18F-Fluorodeoxyglucose Positron Emission Tomography Magnetic Resonance Imaging: A Twist in the Tale.

Demyelinating lesions of the central nervous system (CNS) are classically known to be hypometabolic on 18F-Flurodeoxyglucose Positron Emission Tomography (18F-FDG PET). However, demyelinating lesions may show increased tracer uptake on 18F-FDG PET and can radiologically mimic neoplasm. Delayed tracer uptake on FDG PET is one of the diagnostic hallmarks of primary CNS lymphoma (PCNSL). Here, we present two cases in which the brain lesions showed increased FDG uptake on delayed integrated PET Magnetic Resonance Imaging (MRI), which were pathologically proven as CNS demyelination. Such demyelinating lesions may also act as "sentinel lesions" and potential harbinger of PCNSL on follow-up.

XCalibur aneurysm occlusion device for the treatment of direct carotid cavernous fistula: expansion of armamentarium.

We report the first case of a post-traumatic direct carotid cavernous fistula (CCF) treated with the XCalibur aneurysm occlusion device, which is a balloon mounted stent with flow diversion effect. Two devices were deployed across the fistula in an overlapping manner, resulting in complete occlusion of the fistula. Flow diversion with this device can provide a safe and alternative treatment option in direct CCF.

Streptococcus pluranimalium: Emerging Animal Streptococcal Species as Causative Agent of Human Brain Abscess.

BACKGROUND: Streptococcus pluranimalium is a new and emerging animal streptococcal species associated with primary infection in bovine and avian species. Data in the literature regarding its pathogenic significance in human beings are limited. We hereby report a case of brain abscess caused by S. pluranimalium in a healthy adult male. S. pluranimalium, a causative agent of brain abscess, was unanticipated, and to the best of our knowledge, this is one of the rare cases reported in the medical literature. CASE DESCRIPTION: A 44-year-old male presented with headache and occasional episodes of vomiting for 2 weeks, weakness of the left upper and lower limbs for 1 week, and 1 episode of generalized tonic clonic seizure 2 days back. He was afebrile and had no history of loss of consciousness or head trauma. His physical and neurologic examination was unremarkable. Magnetic resonance imaging of the brain revealed a focal ring enhancing lesion in right posterior parietal lobe, suggestive of infective etiology. The patient underwent right parietooccipital craniotomy and excision of cerebral abscess, from which S. pluranimalium was isolated. The patient responded to treatment with intravenous ceftriaxone, vancomycin, and metronidazole without any residual neurologic sequelae. CONCLUSION: Clinical data regarding epidemiology, pathogenic mechanisms, and zoonotic potential of S. pluranimalium in human beings are lacking. The number of cases of human infections with S. pluranimalium are steadily increasing. Hence further detailed study of the pathogenesis of S. pluranimalium in human beings is warranted, which may help to develop new strategies to prevent and treat infection with this bacterium.

Pseudoxanthoma elasticum and nephrocalcinosis: Incidental finding or an infrequent manifestation?

Pseudoxanthoma elasticum (PXE) is an inherited disorder characterized by generalized fragmentation and progressive calcification of elastic tissue. We report two sporadic cases of PXE, both of whom presented with asymptomatic yellowish papules over the flexural sites for cosmetic reasons. Histopathological findings on hematoxylin and eosin and Verhoeff-Van Gieson (VVG) staining were classical of PXE. In addition to this, renal calcification was documented on plain radiography of kidneys, ureters, and bladder (KUB) in both the cases. Paucity of literature describing the association of nephrocalcinosis with PXE prompted the present report.