## What is/are Four Dimensional Ct?

Four Dimensional Ct - The presence of irregular pulsation detected by four-dimensional CT angiography (4D-CTA) is associated with ruptured aneurysms.^{[1]}We show that an image-based DL risk score derived from a series of four-dimensional CT images varies in a deterministic, sinusoidal trajectory in phase with the respiratory cycle.

^{[2]}Four-dimensional CT image-rendering was performed to determine the presence of reduced leaflet motion (RELM).

^{[3]}Four-dimensional CT (4DCT) can image joints as they move through range of motion (ROM).

^{[4]}For each patient, dose was estimated using Monte-Carlo convolution for helical computed tomography (helical CT), Four-Dimensional CT (4D-CT), and kilovoltage Cone-Beam CT (kV-CBCT).

^{[5]}We aimed to use four-dimensional CT angiography (4D-CTA) to investigate the associations of irregular pulsation of IAs with conventional risk factors and the estimated rupture risk.

^{[6]}Results Tumors were localized by MIBI scans in 190 patients (MIBI [+] group) and by ultrasound or parathyroid four-dimensional CT in 27 patients (MIBI [−] group).

^{[7]}The gross tumour volume (GTV) was segmented in each phase of a four-dimensional CT (4DCT).

^{[8]}In this study, we developed a method for estimating liver elasticity using the finite element method (FEM) and four-dimensional CT (4DCT) images acquired during radiotherapy planning, and we subsequently evaluated its feasibility as a biomarker for liver fibrosis.

^{[9]}The continuous motion of the ribs during tidal breathing was also described using four-dimensional CT datasets from seven participants with thoracic esophageal malignancies.

^{[10]}CONCLUSIONS Four-dimensional CT can provide the detailed findings of VPF that are not possible with conventional CT, and the exposure dose was considered medically acceptable.

^{[11]}We recommend that planar sestamibi imaging, single photon emission computed tomography (SPECT), SPECT/CT, CT neck/mediastinum with contrast, MRI, and four dimensional CT (4D‐CT) may be used in conjunction with high‐resolution neck ultrasound to preoperatively localize pathologic parathyroid glands.

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