Somatom sensation 40

The patients underwent CT scans before the operation with a 64-row volumetric CT machine (SOMATOM Sensation 40, Siemens, Malvern, PA) and 5-mm slice thickness. The images were stored in DICOM format and analyzed by Mimics 17.0 (Materialise, Belgium). The angle and plate of both tibia and femoral distal bone resection and the prosthetic component size were determined before surgery by the 3D printing technology medical application research institute of Changsha and printed by the Beijing Engineering Technology R&D Center. The objective was to achieve a neutral mechanical axis for the femur and tibia. The plans were reviewed and confirmed by the surgeon for each patient. The resection plates of the tibia were designed to be at a 90°angle to the longitudinal tibial axis with a 3° posterior slope. For ensuring the proximal tibia and distal femur resection can be performed precisely, the contact area between the bone and PSI was enlarged and used the osteophytes as the contact surface as much as possible. The flexion degree in the sagittal plane for the femoral component depended on the patient’s specific anatomical features. The templates were sterilized by a plasma sterilizer before surgery. Our group obtained invention patents for the PSI and design method (patent numbers ZL201520623218.2 and ZL201510507788.X).

CT images were obtained with multidetector row CT scanners (Somatom Sensation 40 or Somatom Sensation 64; Siemens AG, Medical Solutions, Business Unit CT, Forchheim, Germany), with a slice thickness of 5 mm. Images were uploaded to a picture archiving and communication system (PACS, GE Healthcare-Centricity RIS CE V2.0, GE Medical Systems, US). CT image analysis was performed with the image post-processing software module (AW module) embedded in this PACS. We selected the cross-sectional CT images at the third lumbar vertebra (L3) as a standard landmark to quantify visceral fat area (VFA) and skeletal muscle area(SMA) according to previous literatures 17 , 21 (link). Two consecutive cross-sectional CT images at L3 level were reformatted by AW module. Preset thresholds of Hounsfield units (HU) were as follows: -190HU to -30HU for fat tissue, and -30HU to 90HU for skeletal muscle tissue. Total abdominal fat volume (including visceral fat and subcutaneous fat) and skeletal muscle volume of selected two consecutive slices were quantified automatically by AW module. Then, we obtained visceral fat volume by removing subcutaneous fat from total abdominal fat manually. Finally, we could calculate VFA and SMA by dividing these measurements by thickness (two consecutive images, 5mm×2 =1cm).

The examinations were carried out either on the recently introduced PCCT (Naeotom Alpha, Siemens Healthineers, Erlangen, Germany) or on a standard CT scanner (SCT, Somatom Sensation 40, Siemens Healthineers, Erlangen, Germany). The characteristics of both scanners are compared in Table 1.

In this study, the Siemens Somatom Sensation 40 CT machine (Siemens, Germany) was adopted to obtain the composition spatial distribution of ingredients and meso-structure information of five specimens. This X-ray CT system is based on cone-beam scanning technology, which consists of a 240 kV/320 W microfocus X-ray source and a radiation detector with a nominal resolution of less than 2 μm. This microfocused X-ray source has a resolution of 1 μm and a minimum distance of 4.5 mm between the focus and the sample. In the experiment, 190 kV lamp voltage and 0.45 mA current value were used. After the CT system was ready, the cylindrical sample was secured to a table on a low-density poly-cylindrical base. In order to receive the X-ray radiation beam evenly in the acquisition system, each specimen was moved up and down automatically during the 1 h scan.

Patients underwent CT scans on multiple CT scanners (SOMATOM Sensation64, SOMATOM Sensation40, SOMATOM Definition AS, Siemens AG Medical Solutions; Brilliance 64, Philips). The acquisition protocol satisfied the following requirements: tube voltage: 120 KV; tube current: 90–270 mA; matrix: 256 × 256; thickness of reconstructed images: 1 mm; three-phases scan; after plain scanning, two-phase contrast-enhanced CT scans were initiated at 30 s (arterial phase), 80 s (venous phase) after injection of the contrast agent. With a high-pressure injector, 100 ml of a nonionic-contrast agent was injected at a rate of 2.5 ml/s.
Preoperative CT scans were recorded and extracted from the picture archiving and communication system in the Department of Radiology at Fudan University Shanghai Cancer Center. The venous-phase CT digital imaging and communication in medicine images were required and then loaded into a personal computer for further radiomics analysis.