Clinical diagnostic reference levels in neuroradiology based on clinical indication.

This study focuses on patient radiation exposure in interventional neuroradiology (INR) procedures, a field that has advanced significantly since its inception in the 1980s. INR employs minimally invasive techniques to treat complex cerebrovascular diseases in the head, neck, and spine. The study establishes diagnostic reference levels (DRLs) for three clinical indications (CIs): stroke (S), brain aneurysms (ANs), and brain arteriovenous malformation (AVM). Data from 209 adult patients were analyzed, and DRLs were determined in terms of various dosimetric and technical quantities. For stroke, the established DRLs median values were found to be 78 Gy cm2, 378 mGy, 118 mGy, 12 min, 442 images, and 15 runs. Similarly, DRLs for brain AN are 85 Gy cm2, 611 mGy, 95.5 mGy, 19.5, 717 images, and 26 runs. For brain AVM, the DRL's are 180 Gy cm2, 1144 mGy, 537 mGy, 36 min, 1375 images, and 31 runs. Notably, this study is unique in reporting DRLs for specific CIs within INR procedures, providing valuable insights for optimizing patient safety and radiation exposure management.

The Brain Tumor Segmentation (BraTS-METS) Challenge 2023: Brain Metastasis Segmentation on Pre-treatment MRI.

Clinical monitoring of metastatic disease to the brain can be a laborious and timeconsuming process, especially in cases involving multiple metastases when the assessment is performed manually. The Response Assessment in Neuro-Oncology Brain Metastases (RANO-BM) guideline, which utilizes the unidimensional longest diameter, is commonly used in clinical and research settings to evaluate response to therapy in patients with brain metastases. However, accurate volumetric assessment of the lesion and surrounding peri-lesional edema holds significant importance in clinical decision-making and can greatly enhance outcome prediction. The unique challenge in performing segmentations of brain metastases lies in their common occurrence as small lesions. Detection and segmentation of lesions that are smaller than 10 mm in size has not demonstrated high accuracy in prior publications. The brain metastases challenge sets itself apart from previously conducted MICCAI challenges on glioma segmentation due to the significant variability in lesion size. Unlike gliomas, which tend to be larger on presentation scans, brain metastases exhibit a wide range of sizes and tend to include small lesions. We hope that the BraTS-METS dataset and challenge will advance the field of automated brain metastasis detection and segmentation.

Rescue Stent Placement for Acute Ischemic Stroke with Large Vessel Occlusion Refractory to Mechanical Thrombectomy: A Multiethnic Middle Eastern/African/Asian Cohort.

PURPOSE: To investigate the safety and effectiveness of rescue stent placement in patients who experienced acute stroke in whom mechanical thrombectomy failed. METHODS: This was a retrospective review of a multiethnic stroke database. After stent placement, an aggressive antiplatelet protocol was followed with glycoprotein IIb/IIIa infusion. The primary outcomes were incidence of intracerebral hemorrhage (ICH), recanalization score, and favorable prognosis (modified Rankin score ≤ 2) at 90 days. A comparison was made between patients from the Middle East and North Africa (MENA) region and those from other regions. RESULTS: Fifty-five patients were included, with 87% being men. The mean age was 51.3 years (SD ±11.8); 32 patients (58%) were from South Asia, 12 (22%) from MENA, 9 (16%) from Southeast Asia, and 2 (4%) from elsewhere. Successful recanalization (modified Thrombolysis in Cerebral Infarction score = 2b/3) was achieved in 43 patients (78%), and symptomatic ICH occurred in 2 patients (4%). A favorable outcome at 90 days was seen in 26 of the 55 patients (47%). Apart from significantly older age-mean, 62.8 years (SD ±13; median, 69 years) versus 48.1 years (SD ±9.3; median, 49 years)-and coronary artery disease burden-4 (33%) versus 1 (2%) (P < .05), patients from MENA had risk factors, stroke severity, recanalization rates, ICH rates, and 90-day outcomes similar to those from South and Southeast Asia. CONCLUSION: Rescue stent placement showed good outcomes and a low risk of clinically significant bleeding in a multiethnic cohort of patients from MENA and South and Southeast Asia, similar to that in published literature.

Ischemia of the parotid gland and adjacent muscles of mastication following middle meningeal artery embolization.

Middle meningeal artery (MMA) embolization is commonly performed as either a first-line or adjunct treatment for chronic subdural hematomas (cSDH). We present the case of a 59 year-old male patient who presented with right hemibody weakness and cognitive impairment and was diagnosed with left-sided cSDH. A left MMA embolization was performed due to the recurrent nature of the chronic subdural hemorrhage and the history of prior craniotomy. On postoperative day 1, the patient developed sudden onset left facial swelling and tenderness, and a contrast computed tomography (CT) of the neck revealed acute ischemia in the left parotid gland, adjacent superior aspect of the left masseter muscle, the left lateral pterygoid, and left temporalis muscles. The patient was treated conservatively with antibiotics, steroids, and analgesics and reported resolution of symptoms on the three-month follow-up. To our knowledge, this is the first reported case of the ipsilateral parotid gland, temporalis muscle, adjacent superior aspect of the masseter muscle, and pterygoid muscle ischemia secondary to non-target particle embolization following MMA embolization in cSDH. Knowledge of normal and variant origin of the MMA and various anastomoses of this vessel with branches of the internal carotid artery (ICA), external carotid artery (ECA), and vertebrobasilar system is crucial to avoid complications during embolization.

Platelet-Neutrophil Association in NETs-Rich Areas in the Retrieved AIS Patient Thrombi.

Histological structure of thrombi is a strong determinant of the outcome of vascular recanalization therapy, the only treatment option for acute ischemic stroke (AIS) patients. A total of 21 AIS patients from this study after undergoing non-enhanced CT scan and multimodal MRI were treated with mechanical stent-based and manual aspiration thrombectomy, and thromboembolic retrieved from a cerebral artery. Complementary histopathological and imaging analyses were performed to understand their composition with a specific focus on fibrin, von Willebrand factor, and neutrophil extracellular traps (NETs). Though distinct RBC-rich and platelet-rich areas were found, AIS patient thrombi were overwhelmingly platelet-rich, with 90% of thrombi containing <40% total RBC-rich contents (1.5 to 37%). Structurally, RBC-rich areas were simple, consisting of tightly packed RBCs in thin fibrin meshwork with sparsely populated nucleated cells and lacked any substantial von Willebrand factor (VWF). Platelet-rich areas were structurally more complex with thick fibrin meshwork associated with VWF. Plenty of leukocytes populated the platelet-rich areas, particularly in the periphery and border areas between platelet-rich and RBC-rich areas. Platelet-rich areas showed abundant activated neutrophils (myeloperoxidase+ and neutrophil-elastase+) containing citrullinated histone-decorated DNA. Citrullinated histone-decorated DNA also accumulated extracellularly, pointing to NETosis by the activated neutrophils. Notably, NETs-containing areas showed strong reactivity to VWF, platelets, and high-mobility group box 1 (HMGB1), signifying a close interplay between these components.

Corpus callosum hematoma, as a rare complication of COVID-19.

A 46-year-old gentleman had a complicated course of COVID-19 pneumonia. Despite the recovery of the respiratory status, he developed corpus callosum hematoma and critical illness neuropathy/myopathy. The clinical situation became more complicated by developing pulmonary embolism that required anticoagulation. Fortunately, the patient made a good recovery.

Mechanical thrombectomy through a 'carotid-carotid bypass'.

An elderly patient presented with acute-onset right-sided weakness and aphasia. A large penumbra was noted in the left middle cerebral artery (MCA) territory without any infarct core. The patient was noted to have a carotid-carotid bypass. This posed certain technical challenge in accessing the intracranial circulation across the carotid bypass; however, the guiding catheter with soft distal segment was successfully navigated coaxially over the aspiration catheter across the bypass and intracranial circulation was accessed for mechanical thrombectomy. Complete recanalisation and reperfusion were achieved with significant neurological recovery of the patient post-thrombectomy. The aim of this report is to emphasise on this rarely encountered situation in thrombectomy and its successful management. The procedure should not be delayed or deferred due to lack of operator experience.

Severe intracranial atherosclerotic disease presenting as symptomatic isolated convexity subarachnoid haemorrhage.

Isolated convexity cortical subarachnoid haemorrhage (cSAH) is a rare form of non-traumatic subarachnoid haemorrhage localised to one or few cortical sulci of the brain without involving the adjacent brain parenchyma or spreading to sylvian fissure, interhemispheric fissure, basal cisterns and ventricles. cSAH has multiple aetiologies described in medical literature. Intracranial high-grade stenosis is rarely presented as cSAH, especially in young adult patients. Patients presenting with cSAH warrant appropriate diagnostic work up to identify and treat the underlying aetiology.

A Case of Anterior Choroidal Artery Occlusion and Stroke Secondary to External Compression.

The anterior choroidal artery (AChA) is a small artery commonly arising from the supraclinoid segment of the internal carotid artery (ICA). The significance of the AChA is related to its strategic supply to various important structures of the brain, such as the optic tract, the posterior limb of the internal capsule, the cerebral peduncle, the lateral geniculate body, medial temporal lobe, medial area of pallidum, and the choroid plexus [J Neurol. 1988;235:387-91]. The AChA syndrome in its complete form consists of the triad of hemiplegia, hemisensory loss, and hemianopia. However, incomplete forms are more frequent in clinical practice [Stroke. 1994;25:837-42]. Isolated infarction in the AChA territory is relatively rare. The presumed pathogenic mechanisms of AChA infarction are cardiac emboli, large-vessel atherosclerosis, dissection of the ICA, small-vessel occlusion, or other determined or undetermined causes [Stroke. 1994;25:837-42 and J Neurol Sci. 2009;281:80-4].

COVID-19 Related Cerebrovascular Thromboembolic Complications in Three Young Patients.

Coronavirus disease 2019 (COVID-19) is a viral illness, caused by the novel severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). It is currently affecting millions of people worldwide and is associated with coagulopathy, both in the venous and arterial systems. The proposed mechanism being excessive inflammation, platelet activation, endothelial dysfunction, and stasis. As an ongoing pandemic declared by WHO in March 2020, health systems worldwide are experiencing significant challenges with COVID-19-related complications. It has been noticed that patients with COVID-19 are at greater risk of thrombosis.

Multiple Microbleeds: A Serious Neurological Manifestation in a Critically Ill COVID-19 Patient.

Coronavirus disease 2019 (COVID-19) is a viral illness caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There is worldwide emerging evidence of multisystem involvement including different neurological manifestations in COVID-19 patients. As a result, healthcare systems worldwide are not only experiencing diagnostic but also therapeutic and prognostic challenges with COVID-19-related complications. Cerebral microbleeds and leukoencephalopathy have been described in COVID-19 patients; although the mechanism remains unknown, possibilities include endotheliitis with thrombotic microangiopathy, excessive inflammation, prolonged respiratory failure, and hypoxemia. We describe here the clinical, radiological, and laboratory findings as well as the 90-day outcome of a 72-year-old gentleman who presented with severe SARS-CoV-2 infection, leading to diffuse cerebral microhemorrhages and ischemic infarct causing severe morbidity. He was tested positive for COVID-19 confirmed by reverse transcriptase polymerase chain reaction.

Baseline Occlusion Angiographic Appearance on Mechanical Thrombectomy Suggests Underlying Etiology and Outcome.

Background: Etiology of a large vessel occlusion is relevant in the management of acute ischemic stroke patients and often difficult to determine in the acute phase. Aims: We aim to investigate whether the angiographic appearance of the occlusion is related to its etiology and outcome. Materials and Methods: Patients without cervical carotid occlusions who underwent mechanical thrombectomy in our center from April 2015 to September 2018 were studied. Demographics, clinical and radiological variables and outcome measures, including etiological classification of stroke, were collected. Underlying intracranial atherosclerosis was estimated according to the presence of stenosis after recanalization. Patients were assigned to groups based on the appearance of the occlusion observed in the first angiogram as "tapered" or "non-tapered." Differences were searched amongst them. Results: 131 patients met inclusion criteria. 31 (23.6%) were "tapered" and 100 (76.3%) non-tapered. Tapered presented lower mean baseline NIHSS (10.3 ± 6.2 vs. 16.1 ± 7.2; p < 0.001), smaller acute infarct cores as CTP CBV ASPECTS (8.6 ± 1.6 vs. 7.2 ± 2.4; p = 0.003), higher proportion of instant re-occlusions (26.7 vs. 8.2%; p = 0.025), fewer complete recanalization (45.2 vs. 71.0%; p = 0.028), and more persistent occlusions (37.5 vs. 10.6%; p = 0.011) on follow up MRA. There were no differences in reperfusion rates (83.9 vs. 84.0%; p = 0.986) nor in good long term functional outcome (50.0 vs. 51.1%; p = 0.921). Intracranial atherosclerosis etiology was more common in tapered than in non-tapered occlusions (54.8 vs. 18.0%; p < 0.001). Conclusion: The angiographic appearance of an occlusion in mechanical thrombectomy patients may determine its etiology, predict likelihood of successful recanalization, and risk of reocclusion.

Transient in-stent stenosis at mid-term angiographic follow-up in patients treated with SILK flow diverter stents: incidence, clinical significance and long-term follow-up.

BACKGROUND: Little is known about in-stent stenosis (ISS) in patients with aneurysms treated with flow diverter (FD) stents. The reported incidence in the literature varies significantly. OBJECTIVE: The aim of this study was to assess the incidence, severity, distribution, clinical significance, and possible predictors for ISS. METHODS: Between July 2012 and June 2016 we retrospectively reviewed all patients treated with SILK FDs in our center. Only cases with short-term (4±2 months) and long-term (>1 year) follow-ups with digital subtraction angiograms were included. ISS was graded as mild (<25%), moderate (25-50%) or severe (>50%). The following predictors for ISS were assessed: gender, age, the presence of subarachnoid hemorrhage, aneurysm size, location, occlusion status, and post-stenting angioplasty. RESULTS: Thirty-six patients met the inclusion criteria. At mid-term follow-up, ISS was observed in 16/36 patients (44%). Eleven patients (69%) had mild ISS, three (19%) moderate, and two (12%) severe ISS. ISS was diffuse in 11 patients (69%) and focal in five patients (31%). All patients were asymptomatic. Thirteen patients were maintained on dual antiplatelet therapy and three on aspirin alone. At long-term follow-up, complete ISS resolution was seen in 11 patients, improvement in three and worsening in two patients. No de novo ISS occurrence was observed. On univariate analysis there was no significant predictor for ISS. CONCLUSIONS: Transient ISS after FD deployment is a common asymptomatic finding on mid-term angiographic follow-up. Complete resolution or improvement at long-term follow-up is seen in most patients who are maintained on dual antiplatelet therapy.

Endovascular glue embolization of a radiation-induced lenticulostriate artery pseudoaneurysm in a pediatric patient with optic pathway glioma: Case report and review of literature.

Radiation-associated vascular changes most commonly present in the form of stenosis, thrombosis and occlusion. However, development of intracranial aneurysms secondary to radiation is far less common and often manifests with rupture. These aneurysms are difficult to treat and associated with high morbidity and mortality when ruptured compared with saccular aneurysms unrelated to radiation treatment. Both surgical and endovascular options are available for treatment of these aneurysms. We present a young patient with a radiation-induced intracranial pseudoaneurysm arising from the lenticulostriate branch of the left middle cerebral artery (MCA); this developed 1 year 4 months after 59.4 Gy of focused radiation to the suprasellar pilomyxoid astrocytoma. The patient successfully underwent endovascular glue embolization of the aneurysm and occlusion of the lenticulostriate artery after unsuccessful trapping of the aneurysm and occlusion of the parent artery using coils. She developed transient hemiparesis of the right side following the procedure, which was managed conservatively. We performed a complete review of the literature dealing with the radiation-induced intracranial aneurysms, their presentation, treatment and outcome.

Extracranial Venous abnormalities: A true pathological finding in patients with multiple sclerosis or an anatomical variant?

OBJECTIVE: To evaluate the extracranial venous anatomy with contrast-enhanced MR venogram (CE-MRV) in patients without multiple sclerosis (MS), and assess the prevalence of various venous anomalies such as asymmetry and stenosis in this population. MATERIALS AND METHODS: We prospectively recruited 100 patients without MS, aged 18-60 years, referred for contrast-enhanced MRI. They underwent additional CE-MRV from skull base to mediastinum on a 3T scanner. Exclusion criteria included prior neck radiation, neck surgery, neck/mediastinal masses or significant cardiac or pulmonary disease. Two neuroradiologists independently evaluated the studies to document asymmetry and stenosis in the jugular veins and prominence of collateral veins. RESULTS: Asymmetry of internal jugular veins (IJVs) was found in 75 % of subjects. Both observers found stenosis in the IJVs with fair agreement. Most stenoses were located in the upper IJV segments. Asymmetrical vertebral veins and prominence of extracranial collateral veins, in particular the external jugular veins, was not uncommon. CONCLUSION: It is common to have stenoses and asymmetry of the IJVs as well as prominence of the collateral veins of the neck in patients without MS. These findings are in contrast to prior reports suggesting collateral venous drainage is rare except in MS patients. KEY POINTS: • The venous anatomy of the neck in patients without MS demonstrates multiple variants • Asymmetry and stenoses of the internal jugular veins are common • Collateral neck veins are not uncommon in patients without MS • These findings do not support the theory of chronic cerebrospinal venous insufficiency • MR venography is a useful imaging modality for assessing venous anatomy.

Canadian Registry of LVIS Jr for Treatment of Intracranial Aneurysms (CaRLA).

INTRODUCTION: Stents reduce the rate of angiographic recurrence of intracranial aneurysms. The newest stent for intracranial use is the Low-profile Visible Intraluminal Support device (LVIS Jr). OBJECTIVE: To assess the efficacy of the new stent in a multicenter retrospective registry. MATERIALS AND METHOD: Centers across Canada using LVIS Jr were contacted and asked to participate in a retrospective registry of consecutive patients treated with LVIS Jr for intracranial aneurysms between January 2013 and July 2015. RESULTS: A total of 102 patients, with saccular aneurysms in 100 patients (72 women; age range 21-78 years; mean 56.0 years; median 57.5 years) were treated with a LVIS Jr stent. The mean maximum diameter of the dome and neck of the aneurysm and dome to neck ratios were 8.3 mm±7.7 mm, 4.4 mm±1.9 mm, and 1.86±1.22, respectively. Angiographic complications arose in 23 patients, clinical complications in 9 patients, and only 3% of permanent neurological deficits occurred. Death occurred in 1 patient, unrelated to the stent. The ruptured status of the aneurysms (OR=3.29; p=0.046) and use of LVIS Jr for bailout (OR=2.54; p=0.053) showed a trend towards significant association with higher angiographic complications. At the last available follow-up, 68 class I, 20 class II, and 12 class III results were seen. CONCLUSIONS: The LVIS Jr stent is a safe and effective device for stent-assisted coiling, with 3% permanent neurological complications. Stent-assisted coiling continues to be technically challenging in cases of ruptured aneurysms and bailout situations.

Quantitative non-contrast measurements improve diagnosing dural venous sinus thrombosis.

INTRODUCTION: The only direct sign of sinus thrombosis on non-contrast computerized tomography (NCCT) is the hyperdense sign. The purpose of our study was to assess quantitative parameters for diagnosis of superficial venous sinus thrombosis and to compare these quantitative criteria with the current standard of qualitative evaluation. METHODS: This retrospective case-control study included 18 patients with acute superficial sinus thrombosis and 18 matched controls. Three blinded readers independently evaluated the NCCT for the presence of hyperdense sign using axial slices only followed by axial slices with multiplanar reformats. Absolute attenuation values and ratios were calculated for thrombosed and non-thrombosed sinuses: Ratiotarget sinus/lowest attenuation sinus, Ratiotarget sinus/basilar artery, Ratiotarget sinus/internal carotid artery, Ratiotarget sinus/temporal lobe, and Ratiotarget sinus/frontal lobe. RESULTS: There was a significant difference in absolute attenuation values and ratios between thrombosed and non-thrombosed sinuses, with the absolute attenuation and the Ratiotarget sinus/lowest attenuation sinus being the most differentiating. The mean attenuation for thrombosed sinuses was 69 Hounsfield units (HU) (95 % CI 65-72 HU) vs. 52 HU (95 % CI 51-54) for non-thrombosed, P < 0.0001. The mean Ratiotarget/lowest attenuation was 1.5 (95 % CI 1.4-1.6) for thrombosed sinuses vs. 1.1 (95 % CI 1.0-1.1) for non-thrombosed, P < 0.0001. Optimal thresholds of 62 HU and 1.3 yielded sensitivities of 81 and 84 %, respectively. Hyperdense sign had a sensitivity of 63 % on axial images and 67 % with the addition of multiplanar reformats. CONCLUSION: Density measurements result in substantial improvement over visual inspection in the diagnosis of superficial venous sinus thrombosis on NCCT.