Radiation dose reduction for CT-guided intrathecal nusinersen administration in adult patients with spinal muscular atrophy.

Intrathecal administration of nusinersen in adult spinal muscular atrophy (SMA) patients with scoliosis and spondylodesis requires image guidance, which is preferably achieved with multi-detector computed tomography (MDCT). As long-term treatment is necessary and patients are young, radiation doses should be reduced to a minimum whilst a sufficient image quality for precise interventional performance should be kept. We compared 44 MDCT standard-dose scans (133.0-200.0 mA) with a hybrid iterative reconstruction (iDose4) to 20 low-dose scans (20.0-67.0 mA) with iterative model reconstruction (IMR), which were performed for procedure planning of intrathecal nusinersen administration in 13 adult patients with SMA and complex spinal conditions. Qualitative image evaluation, including confidence for intervention planning, was performed by two neuroradiologists for standard- and low-dose scans. All 64 MDCT-guided intrathecal administrations of nusinersen were successful. The dose length product (DLP) was significantly lower when using low-dose scanning with IMR (median DLP of standard-dose scans: 92.0 mGy•cm vs. low-dose scans: 34.5 mGy•cm; p < 0.0001). Image quality was significantly reduced for low-dose compared to standard-dose scanning. However, bone/soft tissue contrast and confidence for intervention planning were not significantly impaired in low-dose MDCT according to both readers, showing good inter-reader agreement. Thus, we hereby demonstrate a low-dose MDCT protocol combined with advanced image reconstruction for scanning during procedure planning as a viable option for image guidance in intrathecal nusinersen treatment of adult SMA patients with complex spinal conditions.