Risk Factors for Small Cortical Infarction on Diffusion-Weighted Magnetic Resonance Imaging in Patients With Acute Ischemic Stroke

Mimics and chameleons in stroke

Ischaemic stroke is a treatable medical emergency. In an era of time-dependent reperfusion techniques, it is crucial that an accurate and prompt diagnosis is made. Approximately 30% of patients admitted to hyperacute stroke units are subsequently found not to have a final diagnosis of acute stroke although some of these patients do have incidental or previously symptomatic cerebrovascular disease. These patients do not benefit from thrombolysis and may require the input of other specialists or treatments. Meanwhile, a proportion of patients with acute stroke have unusual presentations and are sometimes initially admitted to general medical admissions units prior to accessing stroke unit care. It is important that atypical presentations of stroke are recognised so that patients are not denied the benefits of stroke unit care and secondary prevention. This article describes some characteristics of common stroke mimics and chameleons, considers how to avoid diagnostic mistakes and discusses the contributory role of imaging.

Diagnostic performance of diffusion-weighted magnetic resonance imaging in differentiating human renal lesions (benignity or malignancy): a meta-analysis

PURPOSE

This study aims to quantitatively evaluate the potential of diffusion-weighted magnetic resonance imaging (DW-MRI) for differentiating malignant and benign human renal lesions.

MATERIALS AND METHODS

A systematic literature was performed to identify previous research related to the diagnostic performance of DW-MRI for determining whether human renal lesions were benign or malignant. ADC values were extracted from normal renal tissue and different lesion types. Data were extracted to assess the diagnostic performance of DW-MRI for differentiating malignant and benign human renal lesions, as well as running threshold effect and heterogeneity.

RESULTS

Nine publications with 11 subsets were eligible for data extraction and diagnostic performance calculation. A total of 988 apparent diffusion coefficient (ADC) measurements were included. The differences in ADC values between benign lesions (2.47 ± 0.81 × 10(-3) mm(2)/s) and malignant lesions (1.81 ± 0.41 × 10(-3) mm(2)/s) were statistically significant (P < 0.001). The diagnostic odds ratio, the overall positive, negative likelihood ratios, pooled weighted sensitivity and specificity with 95% CI were 20.05 (95% CI 12.56-32.02), 3.32 (95% CI 2.13-5.18), 0.20 (95% CI 0.15-0.27), 88% (95% CI 0.84-0.91) and 72% (95% CI 0.67-0.76), respectively. The area under the curve of the summary receiver operating characteristic was 0.90.

CONCLUSIONS

This meta-analysis indicated that DW-MRI had a relatively good diagnostic accuracy in differentiating malignant and benign human renal lesions. We preliminarily recommend that DW-MRI is performed with a maximum b value ranging from 800 to 1000 s/mm(2) at 3.0 T for imaging protocol, and that DW-MRI should be used with caution when the study population includes children.

Cortical Ischemic Lesion Burden Measured by DIR Is Related to Carotid Artery Disease Severity

Background: Over time, exposure to cerebrovascular risk factors and carotid artery disease may cause multiple asymptomatic brain cortical and subcortical microinfarcts, which are commonly found at brain autopsy. So far, lack of convenient neuroimaging tools limited the investigation of grey matter ischemic damage in vivo. We applied the Double Inversion Recovery (DIR) sequence to explore the impact of carotid artery disease on intracortical ischemic lesion load in vivo, taking into account the impact of demographic characteristics and vascular risk factors. Methods: DIR was acquired in 62 patients with common cerebrovascular risk factors stratified in three groups according to carotid artery disease severity. Intracortical lesions scored on DIR (DIRlns) were classified by vascular territory, lobe and hemisphere. White matter hyperintensities (WMHs) volume was also quantified on Fluid Attenuated Inversion Recovery sequence (FLAIR). Results: Among demographic characteristics and cerebrovascular risk variables explored, General Linear Model indicated that age and carotid artery disease were significantly associated to DIRlns. After correcting for age, DIRlns load was found to be significantly dependent on carotid artery stenosis severity (F(2, 58) = 5.56, p = 0.006). A linear positive correlation between DIRlns and WMHs was found after correcting for age (p = 0.003). Conclusions: Carotid disease severity is associated with DIRlns accrual. Microembolism and impaired cerebral hemodynamics may act as physiopathological mechanisms underlying cortical ischemic damage. The role of other factors, such as small vessel disease and the possible interaction with carotid disease, remains to be further explored.

Unilateral borderzone infarction in a young polytrauma patient

Although post-traumatic cerebral infarction is a known complication of craniocerebral trauma, borderzone infarction (BZI) after multiple traumas in young adults are uncommon and published data on this are extremely scant. We present an unusual occurrence of unilateral borderzone infarction in a 21-year-old male who sustained multiple traumas in a traffic accident, which included mild head injury, blunt cardiac injury, right traumatic hemopneumothorax, and three long bone open fractures. Initial head scan revealed mild brain edema, and the BZI was uncovered by a repeated brain CT scan since the patient had a delayed neurological deficit which was incompatible for the injury severity of the head. Comprehensive work-up was performed and a narrowed right internal carotid artery was disclosed by CT angiography. Although unilateral BZI is extremely rare in young patients, emergency physicians should still keep in mind to warrant serial examinations for BZI and early recognition to provide appropriate treatment.