Using Phantomless QCT for evaluating BMD evolution in maintenance hemodialysis patients

Abstract

This study was aimed to investigate the evolution of bone mineral density (BMD) in patients with maintenance hemodialysis (MHD) by using phantom-less quantitative computed tomography (PL-QCT). We collected patients with MHD in Suzhou Hospital of Nanjing Medical University from September 2020 to December 2023 as the prospective observation group. BMD of thoracolumbar vertebra, total hip and femoral neck were measured by PL-QCT. Patients with MHD were divided into 9 groups according to hemodialysis duration. Chest CT scans of patients in prospective observation group were collected during the first three months of MHD and 1 year, 2 years, 3 years after dialysis between January 2017 and December 2023 as the retrospective observation group, and BMD of the twelfth thoracic vertebra was measured. According to the BMD changes among the prospective observation group and the retrospective observation group, the evolution of thoracolumbar vertebral BMD, whole hip BMD and femoral neck BMD were comprehensively analyzed. BMD of thoracolumbar vertebra gradually decreased within 36 months in patients with MHD. Thoracolumbar vertebral BMD tended to increase when hemodialysis duration was more than 36-48 months, and thoracolumbar vertebral BMD increased significantly with hemodialysis duration when hemodialysis duration was more than 60 months, and significantly exceeded the BMD before MHD. BMD of total hip and femoral neck gradually decreased within 36 months in patients with MHD. BMD of total hip and femoral neck increased with hemodialysis duration when hemodialysis duration was more than 72 months, but was almost the same as that of the first year of MHD. In the follow-up evaluation of BMD in MHD patients, it is recommended to use QCT to measure BMD in thoracolumbar vertebrae or hip the first 3 years of MHD, and use QCT to measure BMD in thoracolumbar vertebrae to evaluate changes over 5 years of MHD.

Keywords: Bone mineral density; Evolution; Hemodialysis duration; Maintenance hemodialysis; Phantom-less quantitative computed tomography.

Fig. 1

Shows the measurement of thoracolumbar vertebral BMD by using PL-QCT. The blue circle in (A) refers to the ROI of the measured vertebral body, The ROI is selected from the cancellous region in the middle of the vertebra to maximize ROI while avoiding the cortical bone, basal vein of the vertebral body, osteophyte and other areas. The red circle indicates the ROI of subcutaneous fat and paravertebral muscle on the same layer of the measured vertebral body. (B) shows that vertebral BMD is calibrated by CT values of the ROI of paravertebral muscle and subcutaneous fat on the same level of the measured vertebral body, and the ROI region needs to be adjusted to a normal distribution on the calibration curve. (C) shows coronal ROI.

Fig. 2

Shows the measurement of whole hip BMD and femoral neck BMD by using PL-QCT. (A) shows the ROI of hip muscle and fat in quality control, (B) shows the horizontal state of the femoral neck in axial position, and (C) shows the generated coronal volume projection image of the hip, with the ROI of the femoral neck in the box.

Fig. 3

Shows the changes of thoracolumbar vertebral BMD, whole hip BMD and femoral neck BMD in patients with MHD over hemodialysis duration. As shown in (A), BMD of thoracolumbar vertebrae showed a gradual upward trend after 36–48 months of dialysis. After 60 months of hemodialysis duration, BMD of thoracolumbar vertebrae increased significantly with hemodialysis duration and was significantly higher than the initial stage of dialysis. (B,C) showed that BMD of the whole hip and femoral neck gradually decreased within 36 months of dialysis, and increased with hemodialysis duration after 72 months of hemodialysis duration, but was almost the same as that in the first year of dialysis.

Fig. 4

Shows the changes of thoracolumbar vertebral BMD in patients with MHD over hemodialysis duration. (A) shows a male, 58 years old, with a BMD of 117.0 mg/cm² after 18 months of dialysis; (B) shows a male, 60 years old, with a 77-month dialysis, with a BMD of 154.6 mg/cm²; (C) shows a female, 66 years old, with a 179-month dialysis, with a BMD of 233.1 mg/cm². The BMD of thoracolumbar vertebrae increased significantly after 60 months of hemodialysis duration, and the BMD was significantly higher than that at the initial stage of dialysis.

Fig. 5

Shows the changes of whole hip BMD and femoral neck BMD in patients with MHD over hemodialysis duration. (A) shows a male, aged 66, with a BMD of whole hip and femoral neck of 0.736 and 0.634 g/cm² after 28 months of dialysis; (B) shows a female, aged 65, with BMD of whole hip and femoral neck of 0.766 and 0.670 g/cm² after 72 months of dialysis; (C) shows a female, aged 60, with a dialysis of 183 months. The BMD of the whole hip and femoral neck were 0.797 and 0.722 g/cm², which increased with hemodialysis duration but were almost the same as that at the initial stage of dialysis.