A qualitative study on stakeholder perceptions of digital prosthetic socket fabrication for transtibial amputations.

BACKGROUND: Digital residual limb shape capture (three-dimensional [3D] scanning), computer-assisted design (CAD), and computer-assisted manufacturing with 3D printing technology show promise for a completely digital process of fabricating prosthetic sockets for patients with limb loss. The effectiveness and quality of digitally designed 3D-printed lower extremity prosthetic sockets is understudied, and there is lack of data on the patient and prosthetist experiences with this digital workflow. OBJECTIVE: To obtain stakeholder feedback on the feasibility and acceptability of using a completely digital prosthetic fabrication process consisting of 3D scanning, CAD, and 3D printing in a rehabilitation setting for adults with transtibial limb amputations. STUDY DESIGN: Qualitative design. METHODS: Study participants with a transtibial-level amputation were fit with a prosthetic socket fabricated using digital shape capture with a 3D scanner, CAD, and 3D printing in addition to a traditionally handcasted manually fabricated socket. Participants tried on and evaluated both sockets. Semistructured interviews took place after the fitting appointments. A focus group was conducted with prosthetists to obtain their feedback. Audio data were transcribed verbatim, and an inductive content analysis was undertaken. RESULTS: Eleven patient participants and 3 prosthetists identified 4 main themes: 1) openness and enthusiasm for digital prosthetic fabrication; 2) relative advantages of digital fabrication vs. traditional socket fabrication; 3) readiness of the technology used for adoption in practice; and 4) digital prosthetic workflow and 3D printing implementation considerations. CONCLUSIONS: Patients and prosthetists were enthusiastic about digital prosthetic socket fabrication and saw potential advantages over traditional methods. Both patients and prosthetists had concerns about the durability, safety, and aesthetics of the 3D printed sockets in this study. Further studies are needed to optimize digital prosthetic fabrication with 3D printing in prosthetic practice.

Leveraging non-contrast head CT to improve the image quality of cerebral CT perfusion maps.

Purpose: The purpose of our work is to present a method that utilizes high-quality non-contrast CT (NCCT) images to reduce the noise of CT perfusion (CTP) baseline images to improve the visibility of infarct core in cerebral blood volume (CBV) maps. Methods: First, a theoretical analysis of the CTP imaging system was performed to demonstrate that for both deconvolution- and non-deconvolution-based CTP systems. The noise of CBV maps is profoundly influenced by the baseline image noise. Consequently, baseline noise reduction is extremely effective in improving the contrast-to-noise ratio (CNR) of ischemic lesions in CBV maps. Second, a method was proposed to fuse the freely available NCCT images with the original CTP baseline images. An optimal weighting scheme was derived such that the noise of the fused baseline image is minimized. Third, the impact of the proposed NCCT-baseline fusion method was investigated using five in vivo canine subjects with different infarct core sizes. NCCT and CTP scans were performed following a clinical stroke CT imaging protocol using a 64-slice MDCT. Two of the subjects also received a diffusion-weighted imaging scan using a 3T-MRI scanner to establish the reference diagnosis for the infarct core. Results: For all five canine subjects, the proposed method led to lower CBV noise and better conspicuity of the infarct core. Compared with a standard CTP postprocessing method, the proposed method reduced the CBV noise standard deviation by 70 % ± 24 % and increased the CNR of infarct core by 23 % ± 11 % ( p < 0.01 ). Conclusions: By utilizing the high-quality NCCT images to reduce CTP baseline image noise, the quality of CBV maps and the conspicuity of ischemic infarct core can be effectively improved. The proposed method can be readily implemented with minimal interruption to the existing clinical workflow.

Impacts of photon counting CT to maximum intensity projection (MIP) images of cerebral CT angiography: theoretical and experimental studies.

While CTA is an established clinical gold standard for imaging large cerebral arteries and veins, an important challenge that currently remains for CTA is its limited performance in imaging small perforating arteries with diameters below 0.5 mm. The purpose of this work was to theoretically and experimentally study the potential benefits of using photon counting detector (PCD)-based CT (PCCT) to improve the performance of CTA in imaging these small arteries. In particular, the study focused on an important component of the CTA image package known as the maximum intensity projection (MIP) image. To help understand how the physical properties of a detector quantitatively influence the MIP image quality, a theoretical model on the statistical properties of MIP images was developed. After validating this model, it was used to explore the individual and joint contribution of the following detector properties to the MIP signal-to-noise ratio (SNR): inter-slice noise covariance, spatial resolution along the z direction, and native pixel pitch along z. The model demonstrated that superior slice sensitivity, reduced inter-slice noise correlation, and smaller native pixel pitch along z provided by PCDs lead to improved vessel SNR in MIP images. Finally, experiments were performed by scanning an anthropomorphic cerebral angiographic phantom using a benchtop PCCT system and a commercial MDCT system. The experimental MIP results consistently demonstrated that compared with MDCT, PCCT provides superior vessel conspicuity and reduced artifactual stenosis.