Diffusion-weighted Imaging Restriction Research Articles

Transradial versus transfemoral access for diagnostic cerebral angiography: frequency of acute MRI findings in 500 consecutive patients at a single center

BackgroundThe frequency of clinically symptomatic and asymptomatic diffusion-weighted imaging (DWI) hyperintense lesions and their correlation with the transradial artery (TRA) approach is unclear.ObjectiveTo assess the frequency of abnormal diffusion restriction...

Transradial versus transfemoral arterial approach for cerebral angiography and the frequency of embolic events on diffusion weighted MRI

BackgroundThe radial artery approach has become popular as a ‘radial first’ strategy for arterial access in neuroangiography and neurointerventions. Recent studies have shown that transradial arterial access (TRA) for cerebral...

Postoperative diffusion-weighted imaging and neurological outcome after convexity meningioma resection.

Convexity meningiomas are commonly managed with resection. Motor outcomes and predictors of new deficits after surgery are poorly studied. The objective of this study was to determine whether postoperative diffusion-weighted imaging (DWI) was associated with neurological deficits after convexity meningioma resection and to identify the risk factors for postoperative DWI restriction. A retrospective review of patients who had undergone convexity meningioma resection from 2014 to 2018 was performed. Univariate and multivariate logistic regressions were performed to identify variables associated with postoperative neurological deficits and a DWI signal. The amount of postoperative DWI signal was measured and was correlated with low apparent diffusion coefficient maps to confirm ischemic injury. The authors identified 122 patients who had undergone a total of 125 operations for convexity meningiomas. The median age at surgery was 57 years, and 70% of the patients were female. The median follow-up was 26 months. The WHO grade was I in 62% of cases, II in 36%, and III in 2%. The most common preoperative deficits were seizures (24%), extremity weakness/paralysis (16%), cognitive/language/memory impairment (16%), and focal neurological deficit (16%). Following resection, 89% of cases had no residual deficit. Postoperative DWI showed punctate or no diffusion restriction in 78% of cases and restriction > 1 cm in 22% of cases. An immediate postoperative neurological deficit was present in 14 patients (11%), but only 8 patients (7%) had a deficit at 3 months postoperatively. Univariate analysis identified DWI signal > 1 cm (p < 0.0001), tumor diameter (p < 0.0001), preoperative motor deficit (p = 0.0043), older age (p = 0.0113), and preoperative embolization (p = 0.0171) as risk factors for an immediate postoperative deficit, whereas DWI signal > 1 cm (p < 0.0001), tumor size (p < 0.0001), and older age (p = 0.0181) were risk factors for deficits lasting more than 3 months postoperatively. Multivariate analysis revealed a DWI signal > 1 cm to be the only significant risk factor for deficits at 3 months postoperatively (OR 32.42, 95% CI 3.3-320.1, p = 0.0002). Further, estimated blood loss (OR 1.4 per 100 ml increase, 95% CI 1.1-1.7, p < 0.0001), older age (OR 1.1 per year older, 95% CI 1.0-1.1, p = 0.0009), middle third location in the sagittal plane (OR 16.9, 95% CI 1.3-216.9, p = 0.0026), and preoperative peritumoral edema (OR 4.6, 95% CI 1.2-17.7, p = 0.0249) were significantly associated with a postoperative DWI signal > 1 cm. A DWI signal > 1 cm is significantly associated with postoperative neurological deficits, both immediate and long-lasting. Greater estimated blood loss, older age, tumor location over the motor strip, and preoperative peritumoral edema increase the risk of having a postoperative DWI signal > 1 cm, reflective of perilesional ischemia. Most immediate postoperative deficits will improve over time. These data are valuable when preoperatively communicating with patients about the risks of surgery and when postoperatively discussing prognosis after a deficit occurs.

Heidenhain Variant of Sporadic Creutzfeldt-Jakob Disease: First Reported Case from East Africa

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare prion disease that causes rapidly progressive fatal neurodegeneration. The rarer Heidenhain variant of sCJD presents with visual symptoms and is rarely reported in the literature from sub-Saharan Africa. We report the case of a 57-year-old male with a three-week history of losing direction when driving home and visual hallucinations described as seeing rainbows. Magnetic resonance imaging (MRI) of the brain revealed unilateral parieto-occipital sulcal hyperintensities with restriction on diffusion-weighted imaging (DWI), and electroencephalography (EEG) showed right para-central slowing leading to an initial diagnosis of non-convulsive status epilepticus. He was treated with anti-epileptic medication but was re-admitted less than a month later with worsening spatial memory, aggression, ataxia, dysarthria, myoclonic jerks and a positive startle response, later developing generalised tonic-clonic seizures. Repeat MRI brain scan showed widespread posterior-predominant sulcal DWI restriction in a cortical ribboning pattern pathognomonic for sCJD. EEG showed diffuse slowing, and cerebrospinal fluid was analyzed for abnormal prion protein using real-time quaking-induced conversion but was inconclusive due to suboptimal sample collection. The patient fulfilled the diagnostic criteria for probable sCJD, Heidenhain variant; the family declined brain biopsy for definitive diagnosis. He was subsequently palliated at a local hospice where he died approximately three months after the onset of symptoms. Our case highlights the presence of a rare form of sCJD, and the diagnostic challenges faced in our resource-limited setting.

Acute DWI Reductions In Patients After Single Epileptic Seizures - More Common Than Assumed.

Background: Changes of cerebral diffusivity detected by magnetic resonance imaging (MRI) have been reported in epilepsy. Diffusion weighted imaging (DWI) detects changes in the distribution of water molecules by measuring the apparent diffusion coefficient (ADC) and is mainly used in the diagnosis of ischemic stroke. DWI changes in epilepsy were reported in status epilepticus (SE) or series of seizures. It remains unclear whether this phenomenon also occurs after single seizures. Accordingly, possible pathomechanisms have only been discussed on the presumed basis of ongoing epileptic brain activity.Methods: In this retrospective study, we systematically analyzed DWI alterations related to epileptic seizures in 454 patients who received MRI scanning within the first 24 h after seizure onset.Results: DWI restrictions not classified as ischemic stroke were observed in 18 patients (4%). We found DWI restrictions in 19% of patients with SE/seizure series and in 3% of patients after single focal and 2.5% after single generalized seizures. 17 patients with DWI alterations were diagnosed with a structural epilepsy. DWI signal decreased in the majority of patients within the first days and could not be detected in follow-up imaging >3 months. In all patients except one, DWI alterations were detected in the same hemisphere as the lesion. In the case of seizure series or SE, DWI restrictions mostly presented with a typical “garland-like” pattern alongside the cortical band or on the border of a defined lesion, while in isolated seizures, the restrictions were often rather subtle and small.Discussion: We show that DWI restrictions can be observed in patients after single epileptic seizures. As the vast majority of these patients was diagnosed with an epilepsy due to structural cerebral pathology, DWI restriction may reflect a higher vulnerability in these regions. This might also explain the fact that diffusivity changes were observed after single focal seizures as well as after multiple seizures or SE. The occurence itself on one side as well as the spatial pattern of this phenomenon on the other may thus not only be related to the duration of ictal activity, but to structural pathology.

Focal and Generalized Patterns of Cerebral Cortical Veins Due to Non-Convulsive Status Epilepticus or Prolonged Seizure Episode after Convulsive Status Epilepticus – A MRI Study Using Susceptibility Weighted Imaging

ObjectiveThe aim of this study was to investigate variant patterns of cortical venous oxygenation during status epilepticus (SE) using susceptibility-weighted imaging (SWI).MethodsWe analyzed magnetic resonance imaging (MRI) scans of 26 patients with clinically witnessed prolonged seizures and/or EEG-confirmed SE. All MRI exams encompassed SWI, dynamic susceptibility contrast perfusion MRI (MRI-DSC) and diffusion-weighted imaging (DWI). We aimed to identify distinct patterns of SWI signal alterations that revealed regional or global increases of cerebral blood flow (CBF) and DWI restrictions. We hypothesized that SWI-related oxygenation patterns reflect ictal or postictal patterns that resemble SE or sequelae of seizures.ResultsSixteen patients were examined during nonconvulsive status epilepticus (NCSE) as confirmed by EEG, a further ten patients suffered from witnessed and prolonged seizure episode ahead of imaging without initial EEG. MRI patterns of 15 of the 26 patients revealed generalized hyperoxygenation by SWI in keeping with either global or multifocal cortical hyperperfusion. Eight patients revealed a focal hyperoxygenation pattern related to focal CBF increase and three patients showed a focal deoxygenation pattern related to focal CBF decrease.ConclusionsSWI-related hyper- and deoxygenation patterns resemble ictal and postictal CBF changes within a range from globally increased to focally decreased perfusion. In all 26 patients the SWI patterns were in keeping with ictal hyperperfusion (hyperoxygenation patterns) or postictal hypoperfusion (deoxygenation patterns) respectively. A new finding of this study is that cortical venous patterns in SWI can be not only focally, but globally attenuated. SWI may thus be considered as an alternative contrast-free MR sequence to identify perfusion changes related to ictal or postictal conditions.

Status epilepticus: Clinical characteristics and EEG patterns associated with and without MRI diffusion restriction in 69 patients

ObjectiveIncidence and localization of cortical and thalamic peri-ictal diffusion-weighted imaging (DWI) abnormalities were investigated in patients with status epilepticus (SE). Clinical characteristics and EEG features were compared between patients with and without peri-ictal regional DWI restriction. Such correlations are important to improve the understanding of causes and significance of peri-ictal DWI restriction. MethodsWe retrospectively investigated 69 SE-patients treated in our emergency department in whom SE was confirmed by EEG and MRI including DWI was performed. Results19/69 patients presented with peri-ictal DWI restriction: 18/19 with cortical restriction, 13 of them with additional thalamic restriction, and 1/19 with thalamic restriction only. 17/69 patients had DWI restrictions related to other pathologies, so that a possible overlap with peri-ictal DWI restriction could not be determined. In 33/69 patients no peri-ictal DWI restriction was detected. In contrast to SE-patients without DWI restriction, those with peri-ictal DWI restriction always presented with regional/unilateral epileptiform discharges (p<0.001). The EEG of SE-patients with peri-ictal DWI restriction was predominated by circumscribed periodic lateralized epileptiform discharges (PLEDs) (p<0.001) and by repetitive seizure patterns (p=0.009), while PLEDs occurred infrequently and EEG patterns were more variable in extent in patients without DWI restriction. Patients with peri-ictal diffusion had more often a quantitative disorder of consciousness (p=0.05) compared to patients without peri-ictal DWI restriction. No significant differences were found concerning age of patients, preceding generalized tonic–clonic seizures, and mortality. SignificancePatients with peri-ictal DWI restriction presented with a rather uniform EEG pattern characterized by circumscribed PLEDs possibly resulting from local cortical metabolic disturbances and with intermittent seizure patterns. The frequently observed quantitative disorder of consciousness despite circumscribed EEG patterns could be related to epileptic activity in the temporal lobe and cortico-thalamic synchronization. The higher percentage of bilateral status patterns and subcortical lesions in patients without peri-ictal DWI restrictions suggest a different pathomechanism.

The value of susceptibility-weighted imaging (SWI) in patients with non-neonatal hypoxic-ischemic encephalopathy

ObjectiveIn susceptibility-weighted imaging (SWI) in the normal brain, cortical veins appear hypointense due to paramagnetic properties of deoxy-hemoglobin. Global cerebral anoxia decreases cerebral oxygen metabolism, thereby increasing oxy-hemoglobin levels in cerebral veins. We hypothesized that a lower cerebral oxygen extraction fraction in comatose patients with non-neonatal hypoxic-ischemic encephalopathy (IHE) produces a pattern of global rarefied or pseudo-diminished cortical veins due to higher oxy-hemoglobin. Purpose(1) To investigate the topographic relationship between susceptibility effects in cortical veins and related diffusion restrictions on diffusion-weighted imaging (DWI) in patients with IHE. (2) To relate imaging findings to patterns of altered resting activity on surface EEG. MethodsTwenty-three IHE patients underwent MRI. EEG patterns were used to classify the depth of coma. Regional vs. global susceptibility changes on SWI and patterns of DWI restrictions were compared with the depth of coma. ResultsAll patients exhibited areas of restricted cortical diffusion and SWI abnormalities. The dominant DWI restrictions encompassed widespread areas along the precuneus, frontal and parietal association cortices and basal ganglia. For SWI, nineteen patients had generalized bi-hemispherical patterns, the EEG patterns correlated with coma grades III–V. Four patients had focal decreases of deoxy-hemoglobin following DWI restrictions; associated with normal EEGs. ConclusionFocal patterns of diamagnetic effects on SWI according to relative decreases in deoxy-hemoglobin due to reduced metabolic demand are associated with normal EEG in IHE patients. Global patterns indicated increased depth of coma and widespread cortical damage. Clinical relevanceThe results indicate a potential diagnostic value of SWI in patients with IHE.

Focal hemodynamic patterns of status epilepticus detected by susceptibility weighted imaging (SWI).

To investigate pathological findings in the susceptibility weighted imaging (SWI) of patients experiencing convulsive (CSE) or non-convulsive status epilepticus (NCSE) with focal hyperperfusion in the acute setting. Twelve patients (six with NCSE confirmed by electroencephalogram (EEG) and six patients with CSE with seizure event clinically diagnosed) underwent MRI in this acute setting (mean time between onset of symptoms and MRI was 3h 8min), including SWI, dynamic susceptibility contrast MR imaging (DSC) and diffusion-weighted imaging (DWI). MRI sequences were retrospectively evaluated and compared with EEG findings (10/12 patients), and clinical symptoms. Twelve out of 12 (100%) patients showed a focal parenchymal area with pseudo-narrowed cortical veins on SWI, associated with focal hyperperfused areas (increased cerebral blood flow (CBF) and mean transit time (MTT) shortening), and cortical DWI restriction in 6/12 patients (50%). Additionally, these areas were associated with ictal or postical EEG patterns in 8/10 patients (80%). Most frequent acute clinical findings were aphasia and/or hemiparesis in eight patients, and all of them showed pseudo-narrowed veins in those parenchymal areas responsible for these symptoms. In this study series with CSE and NCSE patients, SWI showed focally pseudo-narrowed cortical veins in hyperperfused and ictal parenchymal areas. Therefore, SWI might have the potential to identify an ictal region in CSE/NCSE. • The focal ictal brain regions show hyperperfusion in DSC MR-perfusion imaging. • SWI shows focally diminished cortical veins in hyperperfused ictal regions. • SWI has the potential to identify a focal ictal region in CSE/NCSE.

ABCD2 as a Screening Tool for Cerebral Infarction on Stroke MRI?

Background: The newly proposed transient ischemic attack (TIA) definition demands for MRI exclusion of infarction. Due to limited resources other tools than MRI predicting tissue infarction would be valuable. We hypothesized that ABCD² risk score is a valid screening tool for diffusion-weighted imaging (DWI) lesions. Methods: TIA patients were prospectively enrolled in an observational MRI study to receive acute and follow-up stroke MRI. ABCD² scores were calculated, and sociodemographics and risk factors were recorded. Results: One hundred and thirty-two TIA patients were enrolled over nine months. Five patients were excluded due to different diagnosis. Forty-five of the 127 remaining patients showed acute ischemic lesions on DWI. Median ABCD² scores for DWI-negative and -positive patients were 4 and 5, respectively. Ordinal, trichotomized and dichotomized ABCD² were significantly associated to DWI. Univariate analysis of single score items and other risk factors demonstrated unilateral weakness, duration of symptoms and smoking as predictive for DWI restrictions. In multivariate analysis unilateral weakness remained significant. Conclusions: High-risk ABCD² score due to the impact of hemiparesis is associated with the occurrence of DWI lesions but is still not accurate enough for a reliable differentiation of cerebrovascular events with and without MRI lesions.

Once upon a Cataract Surgeon

A 60-year-old man presented with diplopia and neurocognitive deficits, which progressed rapidly over several months. Magnetic resonance imaging of the head revealed bilateral signal abnormalities and diffusion-weighted imaging restriction in bilateral basal ganglia, thalami, mesial temporal regions, and periaqueductal gray matter. Cerebrospinal fluid analysis was positive for 14-3-3 and tau proteins. The patient developed progressive neurocognitive decline followed by sleep disturbance and myoclonic jerking consistent with probable Creutzfeldt-Jakob disease.

Bevacizumab-Induced Diffusion Restriction in Patients With Glioma: Tumor Progression or Surrogate Marker of Hypoxia?

TO THE EDITOR: Therapy with bevacizumab results in high response rates in patients with malignant glioma. However, the mechanisms of action of bevacizumab are poorly understood. Blood-brain barrier reconstitution and vascular normalization have been proposed as phenoma distinct from classical effects of antiangiogenic therapy (ie, induction of hypoxia). Refined magnetic resonance imaging may help to clarify this issue. We, therefore, read with great interest the case report recently presented by Gerstner et al in Journal of Clinical Oncology that described an area of restricted diffusion in a patient with malignant glioma treated with bevacizumab as analyzed by diffusion weighted imaging (DWI). The diffusion-restricted area was biopsied. Histology displayed diffuse tumor progression. Therefore, the authors conclude that diffusion-restricted areas in patients with glioma who are treated with antiangiogenic therapy could represent a special pattern of recurrent tumor. We agree with the authors that diffusion restriction occurs in patients treated with bevacizumab. In our recently published analysis, 18 patients treated with bevacizumab were prospectively analyzed for areas of diffusion restriction on DWI, and apparent diffusion coefficient maps were generated. We found that diffusion-restricted areas accompanied by a corresponding apparent diffusion coefficient decrease occurred in 13 patients (65%). Magnetic resonance imaging–based perfusion analysis performed in two patients showed reduction of regional cerebral blood flow and volume that corresponded with diffusion restriction during treatment with bevacizumab. In one patient, a diffusion-restricted area was biopsied, and histology demonstrated atypical necrosis. Furthermore, immunohistochemistry showed heavy nuclear staining for hypoxia inducible factor-1 . Thus, although we agree that increases in DWI might reflect tumor recurrence where dense cell packing occurs, such as in lymphoma, our analysis suggests that alternative causes for diffusion restriction exist. In our series, DWI restriction was common in patients whose diseases were responding to treatment. The atypical necrosis together with the hypoxia inducible factor-1 induction would be compatible with chronic hypoxia induced by prolonged antiangiogenic therapy. Whether antiangiogenic therapy truely induces hypoxia might be relevant given the therapy-resistant phenotype and diffuse infiltrating growth pattern often observed in gliomas after antiangiogenic therapy, as hypoxia might contribute to both phenoma.