Non-Invasive Measurement of Increased Vessel Wall Inflammation by [18F]FDG PET/CT in Patients with Multiple Myeloma upon Allogeneic Hematopoietic Cell Transplantation

Introduction: In patients with multiple myeloma (MM), allogeneic hematopoietic cell transplantation (allo-HCT) is used as a salvage approach, but is also associated with cardiovascular events during follow-up. Here, we investigated whether increased vessel wall inflammation upon allo-HCT can be monitored by [¹⁸F]fluorodeoxyglucose (FDG) PET/CT.

Methods: 15 MM patients underwent [¹⁸F]FDG before and three months after allo-HCT. By analyzing 8 vessel segments per patient, a non-invasive semi-quantitative read-out of the entire vasculature was conducted. Using healthy lung uptake as reference, correlative indices between derived vessel-to-lung ratios (VLR) and uptake from organs of hematopoietic activation (bone marrow [BM]) were determined. A central review investigated baseline and follow-up scans, which provided the delta VLR between both scans.

Results: For all vessels, the pre-therapeutic VLR was 3.04±0.64 (95%CI, 2.68-3.39) and correlated with uptake derived from BM (R=0.67, P<0.01). After HCT, TBR of all investigated vessel segments increased by 20.1% to 3.64±0.72 (95%CI, 3.24-4.05; P=0.0003 vs. pre-therapeutic VLR). Those findings were primarily driven by an increase of VLR in the abdominal (30.2%, P=0.001) and thoracic aorta (aortic arch, 28.4%; ascending aorta, 26%; descending aorta, 18.5%; P<0.05 for all).

Conclusions: Allo-HCT in MM patients was associated with increased vessel wall uptake, in particular in the thoracic and abdominal aorta. Our study suggests that [¹⁸F]FDG PET/CT may be a helpful tool to determine the vessel wall inflammation in MM patients upon allo-HCT.