Carlos Leiva-Salinas

MR imaging of soft-tissue vascular malformations: diagnosis, classification, and therapy follow-up.

Vascular malformations and tumors comprise a wide, heterogeneous spectrum of lesions that often represent a diagnostic and therapeutic challenge. Frequent use of an inaccurate nomenclature has led to considerable confusion. Since the treatment strategy depends on the type of vascular anomaly, correct diagnosis and classification are crucial. Magnetic resonance (MR) imaging is the most valuable modality for classification of vascular anomalies because it accurately demonstrates their extension and their anatomic relationship to adjacent structures. A comprehensive assessment of vascular anomalies requires functional analysis of the involved vessels. Dynamic time-resolved contrast material-enhanced MR angiography provides information about the hemodynamics of vascular anomalies and allows differentiation of high-flow and low-flow vascular malformations. Furthermore, MR imaging is useful in assessment of treatment success and establishment of a long-term management strategy. Radiologists should be familiar with the clinical and MR imaging features that aid in diagnosis of vascular anomalies and their proper classification. Furthermore, they should be familiar with MR imaging protocols optimized for evaluation of vascular anomalies and with their posttreatment appearances. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.315105213/-/DC1.

Arteriopathy Diagnosis in Childhood Arterial Ischemic Stroke Results of the Vascular Effects of Infection in Pediatric Stroke Study

Background and Purpose Although arteriopathies are the most common cause of childhood arterial ischemic stroke (AIS), and the strongest predictor of recurrent stroke, they are difficult to diagnose. We studied the role of clinical data and follow-up imaging in diagnosing cerebral and cervical arteriopathy in children with AIS.Background and Purpose— Although arteriopathies are the most common cause of childhood arterial ischemic stroke, and the strongest predictor of recurrent stroke, they are difficult to diagnose. We studied the role of clinical data and follow-up imaging in diagnosing cerebral and cervical arteriopathy in children with arterial ischemic stroke. Methods— Vascular effects of infection in pediatric stroke, an international prospective study, enrolled 355 cases of arterial ischemic stroke (age, 29 days to 18 years) at 39 centers. A neuroradiologist and stroke neurologist independently reviewed vascular imaging of the brain (mandatory for inclusion) and neck to establish a diagnosis of arteriopathy (definite, possible, or absent) in 3 steps: (1) baseline imaging alone; (2) plus clinical data; (3) plus follow-up imaging. A 4-person committee, including a second neuroradiologist and stroke neurologist, adjudicated disagreements. Using the final diagnosis as the gold standard, we calculated the sensitivity and specificity of each step. Results— Cases were aged median 7.6 years (interquartile range, 2.8–14 years); 56% boys. The majority (52%) was previously healthy; 41% had follow-up vascular imaging. Only 56 (16%) required adjudication. The gold standard diagnosis was definite arteriopathy in 127 (36%), possible in 34 (9.6%), and absent in 194 (55%). Sensitivity was 79% at step 1, 90% at step 2, and 94% at step 3; specificity was high throughout (99%, 100%, and 100%), as was agreement between reviewers (&kgr;=0.77, 0.81, and 0.78). Conclusions— Clinical data and follow-up imaging help, yet uncertainty in the diagnosis of childhood arteriopathy remains. This presents a challenge to better understanding the mechanisms underlying these arteriopathies and designing strategies for prevention of childhood arterial ischemic stroke.

The Vascular Effects of Infection in Pediatric Stroke (VIPS) Study

Understanding the vascular injury pathway is crucial to developing rational strategies for secondary stroke prevention in children. The multicenter Vascular Effects of Infection in Pediatric Stroke (VIPS) cohort study will test the hypotheses that (1) infection can lead to childhood arterial ischemic stroke by causing vascular injury and (2) resultant arteriopathy and inflammatory markers predict recurrent stroke. The authors are prospectively enrolling 480 children (aged 1 month through 18 years) with arterial ischemic stroke and collecting extensive infectious histories, blood and serum samples (and cerebrospinal fluid, when clinically obtained), and standardized brain and cerebrovascular imaging studies. Laboratory assays include serologies (acute and convalescent) and molecular assays for herpesviruses and levels of inflammatory markers. Participants are followed prospectively for recurrent ischemic events (minimum of 1 year). The analyses will measure association between markers of infection and cerebral arteriopathy and will assess whether cerebral arteriopathy and inflammatory markers predict recurrent stroke.

17q25 Locus Is Associated With White Matter Hyperintensity Volume in Ischemic Stroke, But Not With Lacunar Stroke Status

Background and Purpose— Recently, a novel locus at 17q25 was associated with white matter hyperintensities (WMH) on MRI in stroke-free individuals. We aimed to replicate the association with WMH volume (WMHV) in patients with ischemic stroke. If the association acts by promoting a small vessel arteriopathy, it might be expected to also associate with lacunar stroke. Methods— We quantified WMH on MRI in the stroke-free hemisphere of 2588 ischemic stroke cases. Association between WMHV and 6 single-nucleotide polymorphisms at chromosome 17q25 was assessed by linear regression. These single-nucleotide polymorphisms were also investigated for association with lacunar stroke in 1854 cases and 51 939 stroke-free controls from METASTROKE. Meta-analyses with previous reports and a genetic risk score approach were applied to identify other novel WMHV risk variants and uncover shared genetic contributions to WMHV in community participants without stroke and ischemic stroke. Results— Single-nucleotide polymorphisms at 17q25 were associated with WMHV in ischemic stroke, the most significant being rs9894383 (P=0.0006). In contrast, there was no association between any single-nucleotide polymorphism and lacunar stroke. A genetic risk score analysis revealed further genetic components to WMHV shared between community participants without stroke and ischemic stroke. Conclusions— This study provides support for an association between the 17q25 locus and WMH. In contrast, it is not associated with lacunar stroke, suggesting that the association does not act by promoting small-vessel arteriopathy or the same arteriopathy responsible for lacunar infarction.

Responses to the 10 Most Frequently Asked Questions About Perfusion CT

OBJECTIVE The objective of this article is to address the 10 most frequently asked questions radiologists face when planning, performing, processing, and interpreting a perfusion CT study in a patient with clinical suspicion of acute ischemic stroke. CONCLUSION It is important for radiologists using PCT for stroke imaging to be familiar with the perfusion software used at their institution, with the parameters that can be selected during the post-processing and how these may influence the PCT results.

Neuroimaging of Cerebral Ischemia and Infarction

SummaryThe imaging workup for patients with suspected acute ischemic stroke has advanced significantly over the past few years. Evaluation is no longer limited to noncontrast computed tomography, but now frequently also includes vascular and perfusion imaging. Although acute stroke imaging has made significant progress in the last few decades with the development of multimodal approaches, there are still many unanswered questions regarding their appropriate use in the setting of daily patient care. It is important for all physicians taking care of stroke patients to be familiar with current multimodal computed tomography and magnetic resonance imaging techniques, including their strengths, limitations, and their role in guiding therapy.

Imaging of Acute Ischemic Stroke

In this article the individual components of multimodal computed tomography and multimodal magnetic resonance imaging are discussed, the current status of neuroimaging for the evaluation of the acute ischemic stroke is presented, and the potential role of a combined multimodal stroke protocol is addressed.

Gradient of Apparent Diffusion Coefficient Values in Peritumoral Edema Helps in Differentiation of Glioblastoma From Solitary Metastatic Lesions

OBJECTIVE Glioblastoma and solitary metastatic lesions can be difficult to differentiate with conventional MRI. The use of diffusion-weighted MRI to better characterize peritumoral edema has been explored for this purpose, but the results have been conflicting. The purpose of this study was to test the hypothesis that the gradient of apparent diffusion coefficient (ADC) values in peritumoral edema--that is, the difference in ADC values from the region closest to the enhancing tumor and the one closest to the normal-appearing white matter--may be a marker for differentiating glioblastoma from a metastatic lesion. MATERIALS AND METHODS Forty patients, 20 with glioblastoma and 20 with a solitary metastatic lesion, underwent diffusion-weighted brain MRI before surgical resection. The ADC values were retrospectively collected in the peritumoral edema in three positions: near, an intermediate distance from, and far from the core enhancing tumor (G1, G2, and G3). The ADC gradient in the peritumoral edema was calculated as the subtractions ADCG3 - ADCG1, ADCG3 - ADCG2, and ADCG2 - ADCG1. The ADC values in the enhancing tumor, peritumoral edema, ipsilateral normal-appearing white matter, contralateral healthy white matter, and CSF were also collected. RESULTS A gradient of ADC values was found in the peritumoral edema of glioblastoma. The ADC values increased from the region close to the enhancing tumor (1.36 ± 0.24 × 10(-3) mm(2)/s) to the area near the normal-appearing white matter (1.57 ± 0.34 × 10(-3) mm(2)/s). In metastatic lesions, however, those values were nearly homogeneous (p = 0.04). CONCLUSION The ADC gradient in peritumoral edema appears to be a promising tool for differentiating glioblastoma from a metastatic lesion.

The alphabet soup of perfusion CT and MR imaging: terminology revisited and clarified in five questions

The five questions answered in this article revolve around the different parameters resulting from perfusion imaging processing, and this clarifies the frequently confusing terminology used to describe these parameters. More specifically, the article discusses the different imaging techniques and main mathematical models behind perfusion imaging, reviews the perfusion attributes of brain tissue, and proposes a standardized parameter terminology to facilitate understanding and avoid common misinterpretations.

Uncommon Occupational Lung Diseases: High-Resolution CT Findings

OBJECTIVE The purpose of this article is to describe the high-resolution CT (HRCT) features of uncommon occupational lung diseases. CONCLUSION HRCT plays an increasing role in the evaluation of occupational lung diseases. We present several cases of unusual occupational lung diseases and their HRCT findings. The diseases studied were siderosis, talcosis, berylliosis, calcicosis, hypersensitivity pneumonitis (due to wheat flour and isocyanates), and Ardystil syndrome. The characteristic HRCT findings together with clinical features and related occupational history improve the diagnostic accuracy of these diseases.