Pre-transplant imaging evaluation in sickle cell disease: recommended protocols before allogeneic hematopoietic stem cell transplantation

Objective: To review the recommended imaging modalities for pre-transplant evaluation in patients with sickle cell disease (SCD) undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Materials and Methods: This was a narrative review focusing on key imaging techniques employed to assess organ damage and stratify risks prior to HSCT in patients with SCD, including transcranial Doppler (TCD) ultrasonography, brain magnetic resonance imaging (MRI) with magnetic resonance angiography (MRA), MRI for osteonecrosis evaluation, and MRI-based hepatic iron quantification. Results and discussion: TCD, including blind Doppler and TCD imaging (TCDI), plays a critical role in detecting in-creased cerebral blood flow velocities associated with stroke risk. Brain MRI/MRA is essential for identifying silent cerebral infarcts and intracranial vasculopathy, even in patients with normal TCDI velocities. Bone MRI allows early detection of osteonecrosis, which is frequently asymptomatic in SCD. Liver MRI, using R2 relaxometry and T2*-weighting, provides accurate quantification of hepatic iron overload, an important risk factor for transplant-related complications. Cardiac MRI, chest computed tomography, and liver ultrasound are also recommended to help stratify pre-HSCT risk and identify organ damage. Conclusion: A structured imaging protocol is essential for pre-HSCT assessment in SCD. Radiologists play a pivotal role in identifying subclinical organ damage and providing information critical to transplant candidacy and perioperative management.