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Background
Sickle cell disease is an inherited autosomal recessive multisystem disease which affects approximately 300,000 newborns every year. It occurs due to a abnormal sickle cell hemoglobin(HbS), which on deoxygenation and dehydration, leads to formation of polymers with normal Hb within RBCs leading to formation of abnormal, rigid, sickle shaped RBCs. These abnormal sickle shaped cells are prone to earlier destruction leading to hemolytic anemia and adhere to vascular endothelium leading to occlusion of blood vessels and ischemia; which manifests as painful vaso-occlusive crisis clinically and eventually tissue infarction which produces a myriad of radiological manifestations.

Educational Goals / Teaching Points
The aim of this educational exhibit is to review the pathophysiology of sickle cell disease, describe the radiological features of sickle cell disease involving multiple organ systems (Neurological, Pulmonary, Cardiovascular, Abdominal, Hematopoietic and Musculoskeletal).

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Sickle cell disease can affect all organ systems of the body, thus various imaging modalities are used for diagnosis including plain radiographs, CT and MRI. Pulmonary complications are the most common cause of morbidity and mortality in sickle cell patients. Pulmonary complications include acute chest syndrome (ACS) and pneumonia which can be diagnosed on plain radiographs and CT. Repeated episodes of ACS lead to chronic interstitial lung disease. Neurological involvement occurs due to vaso-occlusive crisis or sequestration crisis leading to brain ischemia and infarcts. 22% children with Sickle cell disease can suffer from silent infarcts which predominantly involve frontal and parietal lobes. Musculoskeletal involvement presents as extramedullary hematopoiesis, bone ischemia and increased susceptibility to osteomyelitis. CT and MRI are modalities of choice for diagnosing MSK complications. The characteristic patterns of bone ischemia include ‘H shaped vertebrae’, dactylitis of hands and feet in young children and avascular necrosis or osteonecrosis. The cardiovascular manifestations occur due to right heart failure due to pulmonary hypertension which can be readily diagnosed on CT/CTA chest. Chronic anemia predisposes to left ventricular hypertrophy and diastolic dysfunction. The abdominal manifestations of sickle cell involve the liver, gall bladder, spleen and the kidneys. Recurrent transfusions in sickle cell patients can lead to hepatic and splenic hemosiderosis. There can be splenomegaly due to sequestration crisis or auto splenectomy with atrophied spleen due to repeated microinfarction. Increased RBC destruction by reticuloendothelial cells increases the risk of pigment gallstones. Renal involvement develops due to sickling of cells in renal vessels causing cortical infarctions and papillary necrosis.

Conclusion
It is imperative to be familiar with imaging findings of sickle cell disease as it plays a crucial role for early diagnosis, to recognize and treat complications, implement the appropriate management and prevent unnecessary surgical interventions in Sickle cell disease.