Imaging Pearls ❯ Syndromes in CT ❯ Sickle Cell Disease
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- “Sickle cell disease (SCD), one of the most common inherited genetic syndromes in the USA, is characterized by recurring episodes of acute illness and progressive multisystem organ injury. Individuals with SCD frequently present to the emergency department for a spectrum of complications, such as vaso-occlusive crises, infection, cholecystitis, and stroke. Imaging correlates for most of these presentations exist, positioning the emergency radiologist to play a pivotal role in facilitating patient care. Using a systems-based approach, we describe the acute and chronic imaging manifestations of SCD that an emergency radiologist can expect to encounter in most practice settings, highlighting the unique pathophysiology of this disorder that typically underlies the imaging findings.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - “Globally, there is an estimated inci- dence of 300,000–400,000 cases of SCD live births per year. In the USA, it is estimated that 1:365 African-Americans and 1:16,350 Hispanic-Americans are born with the homogenous form (sickle cell anemia), and around 1:13 African-Americans have sickle cell trait. Though the incidence of SCD in the USA is declining, medical costs associated with the manifold complications continue to represent a significant economic burden, with an estimated average annual per-person cost of > $10,000 for pediatric patients and > $30,000 for adult patients [4]. Imaging plays an important role in the diagnosis and treat- ment of the disease.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "ACS is one of the most common pulmonary manifestations of SCD and, as in other complications, is attributed to tissue ischemia from microvascular occlusion, precipitated by deox- ygenated states. Although the inciting mechanism for ACS is incompletely understood, conditions that have been associated with predisposition to ACS in SCD include pneumonia, fat emboli originating from infarcted bone marrow, and pulmo- nary infarction mediated by vascular occlusion from deep ve- nous thrombosis/pulmonary embolism. The diagnosis of ACS requires both an acute pulmonary illness, clinically characterized by anemia, fever, chest pain, cough, dyspnea, tachypnea, tachycardia, or cyanosis, and the presence of a new pulmonary opacity or consolidation involving at least one complete lung segment on radiograph or computed tomography (CT).”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "Of note, 30–60% of patients who are subsequently diagnosed with ACS will not have an imaging abnormality on initial presentation but will develop an airspace opacity on follow-up imaging. Due to effective immune compromise from autosplenectomy in this population, sickle cell patients are especially predisposed to pneumonia (especially encapsulated organisms) as compared with the general population. Consequently, it is often difficult to confidently exclude pneumonia on the basis of imaging alone when a new lung opacity is identified.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - “Cardiomyopathy is common in SCD and is multifactorial in etiology, often related to high-output heart failure in the set- ting of chronic anemia, iron overload, and additional volume overload related to renal insufficiency. Pulmonary hypertension can lead to left heart failure and cor pulmonale. Additionally, myocardial fibrosis related to chronic microvascular occlusion contributes to diastolic dysfunction and further impairment of cardiac function. Cardiac and left atrial enlargement can easily be identified on chest radiographs and CT. Contrast-enhanced CT of the chest may reveal myocardial thinning in areas of previous myocardial infarction, reported in 7–30% of SCD patients. Myocardial fibrosis is best evaluated with cardiac MRI, although it is typically not uti- lized in the emergent setting.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "The spleen is universally affected in SCD. Repeated episodes of VOC lead to splenic autoinfarction and functional hypo- or asplenia, usually occurring within the first 2 years of life. An autoinfarcted spleen is easily recognized on CT and frequently on plain radiography as a contracted, calcified left upper quadrant mass. Functional asplenia from autoinfarction is associated with a susceptibility to infection, particularly by encapsulated bacteria; therefore, prophylactic administration of penicillin and pneumococcal vaccine is rec- ommended in childhood.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "Rapid accumulation of blood within a visceral organ can result in acute sequestration syndrome, leading to profound anemia, hemodynamic shock, and, in some cases, death. While acute sequestration syndrome is frequently precipitated by infection, the precise mechanism is unclear. Splenic se- questration, which occurs much more commonly than hepatic sequestration, usually occurs in the pediatric population since most adult spleens SCD have undergone complete autoinfarction . The most common imaging finding of splenic sequestration is a heterogeneously enlarged spleen. In some instances, multiple peripheral infarcts or perisplenic hemorrhage may be present.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "Early renal manifestations of SCD include hyposthenuria (inability to concentrate urine), polyuria, and enuresis. Later complications include proteinuria, nephrotic syndrome, hematuria, and papillary necrosis. Approximately 50% of in- dividuals with SCD have enlarged kidneys on imaging, likely related to increased renal blood volume and glomerular hypertrophy.
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - “Two important entities with a particular association with SCD include segmental infarction and papillary necrosis. As with any other solid abdominal organ, acute renal infarction appears as peripheral, wedge-shaped hypoattenuating areas on contrast- enhanced CT and may be associated with mild mass effect from edema. Perirenal hematomas can rarely occur in acute renal infarction. Remote infarcts are characterized by focal cortical scarring. It is estimated that renal papillary necrosis affects up to 50% of individuals with SCD. Papillary necrosis is optimally depicted on excretory phase contrast-enhanced CT as calyceal blunting or excreted contrast enveloping necrotic, sloughed papillae (golf ball-on-tee sign).”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "An estimated 30% of SCD patients will be diagnosed with sickle cell–related avascular necrosis (AVN) in their lifetime. A 2018 study in children with SCD matched patients with AVN with children without AVN demonstrated that VOC frequency was the strongest independent predictor of the development of AVN. Vaso-occlusion within the medullary capillaries of long bones can present with acute bone pain, a common symptom leading to visits to the emergency department in this population. Over time, this phenomenon leads to frank bone infarction, reactive sclerosis, and new bone formation.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "Typically, EMH occurs in the abdomen, presenting as hepatosplenomegaly or focal soft tissue masses in the peritoneum. In other instances, however, EMH can manifest as soft tissue masses in the musculoskeletal system. A study of EMH in a cohort of patients with anemias of different etiologies demonstrated that a majority of cases with mass-like EMH occurred along the axial skeleton, predominantly in paraspinal regions of the thoracic spine or sacrum . On CT, EMH typically presents as heterogeneous hypovascular paraspinal soft tissue masses with lipid- rich regionS. The masses are typically bilateral in the thoracic spine. While EMH is typically an incidental finding, the soft tissue can occur in the epidural space, encasing neural foramina and, rarely, the spinal canal, resulting in symptomatic myelopathy.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164 - "CD is a relatively common inherited hemoglobinopathy that presents with a spectrum of manifestations that can impact any number organ systems, particularly the lungs, cardiovascular system, abdominal viscera, musculoskeletal system, neuro- logical system, and neurovasculature. Its protean effects on these organs are attributable to both acute and cumulative effects of microvascular ischemia. Hospital resource utiliza- tion for individuals with SCD is high and includes frequent medical imaging to assist in the diagnosis of complications from an early age. Since much of the imaging of SCD occurs out of the emergency department, the emergency radiologist should have an understanding of the relationship between the unique pathophysiology of SCD as well as a familiarity of the range of imaging appearances in the acute and chronic setting, some of which are rare in the general population, but notably distinctive for this population.”
Imaging review of sickle cell disease for the emergency radiologist
Shenise N. Gilyard et al.
Emergency Radiology (2021) 28:153–164