Neuroradiology

Kober, Tobias; ,

doi: 10.1007/s00234-022-02906-zpmid: 35076715

Pemberton, Hugh G.; Zaki, Lara A. M.; Goodkin, Olivia; Das, Ravi K.; Steketee, Rebecca M. E.; Barkhof, Frederik; Vernooij, Meike W.

doi: 10.1007/s00234-022-02923-ypmid: 35303140

Haller, Sven; Van Cauter, Sofie; Federau, Christian; Hedderich, Dennis M.; Edjlali, Myriam

doi: 10.1007/s00234-021-02890-wpmid: 35098343

Artificial intelligence (AI)-based tools are gradually blending into the clinical neuroradiology practice. Due to increasing complexity and diversity of such AI tools, it is not always obvious for the clinical neuroradiologist to capture the technical specifications of these applications, notably as commercial tools very rarely provide full details. The clinical neuroradiologist is thus confronted with the increasing dilemma to base clinical decisions on the output of AI tools without knowing in detail what is happening inside the “black box” of those AI applications. This dilemma is aggravated by the fact that currently, no established and generally accepted rules exist concerning best clinical practice and scientific and clinical validation nor for the medico-legal consequences in cases of wrong diagnoses. The current review article provides a practical checklist of essential points, intended to aid the user to identify and double-check necessary aspects, although we are aware that not all this information may be readily available at this stage, even for certified and commercially available AI tools. Furthermore, we therefore suggest that the developers of AI applications provide this information.

Wittstock, Matthias; Walter, Uwe; Volmer, Erik; Storch, Alexander; Weber, Marc-André; Großmann, Annette

doi: 10.1007/s00234-022-02914-zpmid: 35184205

Cerebral venous and sinus thrombosis (CVST) after adenovirus-vectored COVID-19 ChAdOx1 nCov-19 (Oxford–AstraZeneca) and Ad26.COV2.S (Janssen/Johnson & Johnson) is a rare complication, occurring mainly in individuals under 60 years of age and more frequently in women. It manifests 4–24 days after vaccination. In most cases, antibodies against platelet factor-4/polyanion complexes play a pathogenic role, leading to thrombosis with thrombocytopenia syndrome (TTS) and sometimes a severe clinical or even fatal course. The leading symptom is headache, which usually increases in intensity over a few days. Seizures, visual disturbances, focal neurological symptoms, and signs of increased intracranial pressure are also possible. These symptoms may be combined with clinical signs of disseminated intravascular coagulation such as petechiae or gastrointestinal bleeding. If TTS-CVST is suspected, checking d-dimers, platelet count, and screening for heparin-induced thrombocytopenia (HIT-2) are diagnostically and therapeutically guiding. The imaging method of choice for diagnosis or exclusion of CVST is magnetic resonance imaging (MRI) combined with contrast-enhanced venous MR angiography (MRA). On T2*-weighted or susceptibility weighted MR sequences, the thrombus causes susceptibility artefacts (blooming), that allow for the detection even of isolated cortical vein thromboses. The diagnosis of TTS-CVST can usually be made reliably in synopsis with the clinical and laboratory findings. A close collaboration between neurologists and neuroradiologists is mandatory. TTS-CVST requires specific regimens of anticoagulation and immunomodulation therapy if thrombocytopenia and/or pathogenic antibodies to PF4/polyanion complexes are present. In this review article, the diagnostic and therapeutic steps in cases of suspected TTS associated CSVT are presented.

Martín-Noguerol, Teodoro; Barousse, Rafael; Luna, Antonio; Socolovsky, Mariano; Górriz, Juan M.; Gómez-Río, Manuel

doi: 10.1007/s00234-022-02916-xpmid: 35212785

PurposeTo perform a review of the physical basis of DTI and DCE-MRI applied to Peripheral Nerves (PNs) evaluation with the aim of providing readers the main concepts and tools to acquire these types of sequences for PNs assessment. The potential added value of these advanced techniques for pre-and post-surgical PN assessment is also reviewed in diverse clinical scenarios. Finally, a brief introduction to the promising applications of Artificial Intelligence (AI) for PNs evaluation is presented.MethodsWe review the existing literature and analyze the latest evidence regarding DTI, DCE-MRI and AI for PNs assessment. This review is focused on a practical approach to these advanced sequences providing tips and tricks for implementing them into real clinical practice focused on imaging postprocessing and their current clinical applicability. A summary of the potential applications of AI algorithms for PNs assessment is also included.ResultsDTI, successfully used in central nervous system, can also be applied for PNs assessment. DCE-MRI can help evaluate PN's vascularization and integrity of Blood Nerve Barrier beyond the conventional gadolinium-enhanced MRI sequences approach. Both approaches have been tested for PN assessment including pre- and post-surgical evaluation of PNs and tumoral conditions. AI algorithms may help radiologists for PN detection, segmentation and characterization with promising initial results.ConclusionDTI, DCE-MRI are feasible tools for the assessment of PN lesions. This manuscript emphasizes the technical adjustments necessary to acquire and post-process these images. AI algorithms can also be considered as an alternative and promising choice for PN evaluation with promising results.

McDonough, Rosalie V.; Qiu, Wu; Ospel, Johanna M.; Menon, Bijoy K.; Cimflova, Petra; Goyal, Mayank

doi: 10.1007/s00234-021-02830-8pmid: 34668040

PurposeMedium vessel occlusions (MeVOs) can be challenging to detect on imaging. Multiphase computed tomography angiography (mCTA) has been shown to improve large vessel occlusion (LVO) detection and endovascular treatment (EVT) selection. The aims of this study were to determine if mCTA-derived tissue maps can (1) accurately detect MeVOs and (2) predict infarction on 24-h follow-up imaging with comparable accuracy to CT perfusion (CTP).MethodsTwo readers assessed mCTA tissue maps of 116 ischemic stroke patients (58 MeVOs, 58 non-MeVOs) and determined by consensus: (1) MeVO (yes/no) and (2) occlusion site, blinded to clinical or imaging data. Sensitivity, specificity, and area under the curve (AUC) for MeVO detection were estimated in comparison to reference standards of (1) expert readings of baseline mCTA and (2) CTP maps. Volumetric and spatial agreement between mCTA- and CTP-predicted infarcts was assessed using concordance/intraclass correlation and Dice coefficients. Interrater agreement for MeVO detection on mCTA tissue maps was estimated with Cohen’s kappa.ResultsMeVO detection from mCTA-derived tissue maps had a sensitivity of 91% (95% CI: 80–97), specificity of 82% (95% CI: 70–90), and AUC of 0.87 (95% CI: 0.80–0.93) compared to expert reads of baseline mCTA. Interrater reliability was good (0.72, 95% CI: 0.60–0.85). Compared to CTP maps, sensitivity was 87% (95% CI: 75–95), specificity was 78% (95%CI: 65–88), and AUC was 0.83 (95% CI: 0.76–0.90). The mean difference between mCTA- and CTP-predicted final infarct volume was 4.8 mL (limits of agreement: − 58.5 to 68.1) with a Dice coefficient of 33.5%.ConclusionmCTA tissue maps can be used to reliably detect MeVO stroke and predict tissue fate.

Singh, Nishita; Bala, Fouzi; Kim, B. J.; Najm, Mohamed; Ahn, Seong Hwan; Fainardi, Enrico; Rubiera, Marta; Khaw, Alexander V.; Zini, Andrea; Goyal, Mayank; Menon, Bijoy K.; Almekhlafi, Mohammed

doi: 10.1007/s00234-021-02837-1

Vitali, Paolo; Savoldi, Filippo; Segati, Flavia; Melazzini, Luca; Zanardo, Moreno; Fedeli, Maria Paola; Benedek, Adrienn; Di Leo, Giovanni; Menicanti, Lorenzo; Sardanelli, Francesco

doi: 10.1007/s00234-021-02810-ypmid: 34647143

PurposeImaging of brain involvement in infective endocarditis can drive the clinical management of this serious condition. MRI is very sensitive, but CT is more readily available. In this retrospective study, we compared the detection rates of CT and MRI.MethodsAfter Ethics Committee approval, we retrospectively reviewed a series of 20 patients (13 males, median age 64 years) who underwent both CT and MRI either before or after cardiac surgery for definite infective endocarditis. Plain CT and MRI were evaluated for acute ischemic lesions, both punctuate and large, intraparenchymal hemorrhages, cerebral microbleeds, subarachnoid hemorrhages, abscesses, microabscesses, and meningitis. Qualitative assessment and McNemar test were performed. The value of contrast-enhanced scans (MRI, n = 14; CT, n = 9) and cognitive status were also assessed.ResultsA total of 166 lesions were identified on either technique: 137 (83%) on MRI only, 4 (2%) on CT only, and 25 (15%) on both techniques (p < 0.001). For these last 25 lesions, concordance on lesion type was only 16/25 (64%). MRI detected more microbleeds and ischemic lesions, while the 4 CT-only findings were false positives. Contrast-enhanced scans identified 68 enhancing lesions, mainly abscesses and microabscesses, and allowed a better characterization for 61/117 lesions (52%) with MRI, and for 11/81 (14%) with CT. Follow-up identified mild cognitive impairment in 6/13 and dementia in 3/13 patients.ConclusionWhile CT rapidly excludes large hemorrhages in patients with infective endocarditis, MRI accurately distinguishes the whole spectrum of brain lesions, including small ischemic lesions, microbleeds, and microabscesses.

Vyas, Sameer; Choudhary, Neha; Modi, Manish; Sankhyan, Naveen; Suthar, Renu; Saini, Arushi Gahlot; Bansal, Arun; Sharma, Navneet; Singh, Paramjeet

doi: 10.1007/s00234-021-02831-7pmid: 34657167

PurposeVascular complications can be seen in various viral CNS infections. Variable neuro-imaging findings have been described in the literature elucidating the parenchymal changes with vascular involvement. Vessel wall imaging (VWI) can help to detect these vascular involvements. We aimed to describe the role and usefulness of VWI in the evaluation of various viral CNS infections.MethodsIn this prospective study, we included 15 cases of various diagnosed viral CNS infections (varicella, HIV encephalopathy, HSV encephalitis, Japanese encephalitis, dengue, COVID-19). VWI and time-of-flight MR angiography (TOF MRA) were included in imaging protocol. All cases were evaluated for the presence of cerebral parenchymal changes, vascular enhancement, and vascular stenosis.ResultsWe found infarctions in all 5 cases of varicella, 1 case of HIV encephalopathy, and 1 case of COVID-19 encephalopathy. All these cases also showed vascular enhancement and stenosis on VWI. The rest of the cases, including 1 case of HIV encephalopathy, 3 cases of herpes encephalitis, 2 cases of dengue, and 2 cases of Japanese encephalitis did not have any vascular complication, and also did not show vascular enhancement or stenosis.ConclusionVWI can be useful in the detection of vascular involvement in various viral infections of CNS which show a relatively higher cerebrovascular complication rate like varicella, HIV encephalopathy, and COVID-19. However, VWI may not be useful in the routine evaluation of other viral infections like herpes, dengue, and Japanese encephalitis, which have a very low rate of cerebrovascular complication rate.

Buch, Karen; Hakimelahi, Reza; Locascio, Joseph J.; Bolar, Divya S.; Gonzalez, R. Giliberto; Schaefer, Pamela W.

doi: 10.1007/s00234-021-02835-3pmid: 34664110

PurposeTo assess the utility of ASL in evaluating patients presenting to the ED with stroke-like symptoms.MethodsASL and DWI images from 526 consecutive patients presenting to the ED with acute stroke symptoms were retrospectively reviewed. DWI images were evaluated for volume of restricted diffusion using ABC/2. ASL maps were evaluated for decreased, normal, or increased signal. The volume of decreased ASL signal was calculated using the same ABC/2 technique. The volume of decreased ASL signal was correlated with the volume of DWI signal abnormality to identify cases of mismatch (DWI:ASL ratio > 1.8) and to correlate this mismatch with infarct growth on imaging follow-up. NIHSS, length of hospital stay, mRS, and future admission for acute stroke-like symptoms were recorded. Correlations between ASL abnormalities and clinical parameters were evaluated using a two-tailed t-test.ResultsOf the 526 patients presenting with acute stroke symptoms, 136 patients had an abnormal ASL scan and 388 patients had a normal ASL scan. Of the 136 patients with abnormal ASL, 84 patients had low ASL signal with 79 of these being related to acute infarcts. Elevated ASL signal was seen in 52 patients, of which 30 of these patients had reperfusion hyperemia related to acute infarctions. ASL had a negative predictive value of 94% for evaluating patients with acute ischemic stroke. A subset of patients with abnormal ASL scans with a discharge diagnosis of acute infarction were found to have an ASL:DWI mismatch (ratio > 1.8) and demonstrated significant lesion growth on follow-up imaging (57%). This included some patients who exhibited low ASL signal before development of diffusion restriction (infarction).ConclusionIn patients presenting to the ED with acute stroke symptoms, ASL provides information not available with DWI alone. The NPV of ASL for evaluating patients with acute ischemia was 94%.