Susceptibility-Weighted MR Imaging: A Review of Clinical Applications in Children

Abstract

SUMMARY: Susceptibility-weighted imaging (SWI) is a high-spatial-resolution 3D gradient-echo MR imaging technique with phase postprocessing that accentuates the paramagnetic properties of blood products such as deoxyhemoglobin, intracellular methemoglobin, and hemosiderin. It is particularly useful for detecting intravascular venous deoxygenated blood as well as extravascular blood products. It is also quite sensitive to the presence of other substances such as iron, some forms of calcification, and air. We have used this technique in the past several years to study a wide variety of pediatric neurologic disorders. We present a review with selected case histories to demonstrate its clinical usefulness in the improvement of the following: 1) detection of hemorrhagic lesions seen in various conditions, including traumatic brain injury and coagulopathic or other hemorrhagic disorders; 2) detection of vascular malformations such as cavernous angiomas, telangiectasias, or pial angiomas associated with Sturge-Weber syndrome; 3) demonstration of venous thrombosis and/or increased oxygen extraction in the setting of infarction, hypoxic/anoxic injury, or brain death; 4) delineation of neoplasms with hemorrhage, calcification, or increased vascularity; and 5) depiction of calcium or iron deposition in neurodegenerative disorders. SWI has provided new understanding of some of these disease processes. It is hoped that as SWI becomes more widely available, it will provide additional diagnostic and prognostic information that will improve the care and outcome of affected children.

“Brush Sign” on Susceptibility-Weighted MR Imaging Indicates the Severity of Moyamoya Disease

“…Uncoupling between oxygen supply and demand in hypoperfused tissue may cause a relative increase of deoxyhemoglobin levels and a decrease of oxyhemoglobin in the tissue capillaries and the draining veins. Therefore, SWI has been applied to various pathologies of the brain that affect magnetic inhomogeneity, such as stroke, 8,11 trauma, 8 cerebral cavernous malformation, 12,13 arteriovenous malformation, 14 dural arteriovenous fistula, 15 pathophysiology affecting iron storage conditions, [16][17][18] brain tumor, 19 and cerebral amyloid angiopathy. 20 It is noteworthy that this method has the potential to demonstrate increased oxygen extraction in focal cerebral ischemia.…”

“…In particular, SWI has been accepted as a method available to evaluate deep venous flow in acute or chronic ischemia and to demonstrate increased oxygen extraction in focal cerebral ischemia. 8 Here, we first describe the characteristics of the signal intensity of DMVs by using SWI. We then determine whether this SWI could be used to assess the severity of the hemodynamics in MMD by evaluating the correlation between SWI stage and hemodynamics, including CBF and CVR, on SPECT.…”

In the Eye of Experimental Cerebral Malaria

“…16,18 T 1 -weighted imaging allowed the detection of focal hemorrhages, a hallmark of the disease, and infarction in some patients 14 -16,19 at the cortical and subcortical levels, believed to be a consequence of parasitized erythrocytes obstructing capillaries. 15,16 More recently, susceptibility-weighted imaging 20 has proved more sensitive in the detection of petechiae and seems to correlate better with postmortem findings of diffuse petechial hemorrhages. 17 We previously demonstrated that MRI provides specific and reliable markers of ECM that could help decipher some of the pathogenic processes underlying this cerebral syndrome.…”

Interdisciplinary Approach to Neurocritical Care in the Intensive Care Nursery

“…47 Susceptibility-weighted imaging is useful for detecting blood products, and vascular imaging (MR angiogram and MR venogram) can be useful when evaluating hemorrhage, vascular malformations, and venous sinus thrombosis. [48][49][50] Developmental Care and the Follow-Up Specialist…”