Real-time target moving monitoring algorithm in respiration gating system

This study proposes the use of the ScanNet real-time target moving monitoring method that allows the therapist to set up three primary color detection threshold values, the detection range, the automatic compensation of the distance of the device and the angle of the device. Moreover, the real-time images detected are used for reminding the patient to maintain the therapeutic posture. If the displacement exceeds the permitted range, an alert message will be sent out. Moreover, because the operation is simple, and the system requirements are not too demanding, ScanNet, in addition to its use in monitoring displacement during radiation therapy, can be applied to MRI and other treatments that require the patient to maintain a position for a long time or on patients receiving residential respiratory therapy.

Dependence of Intravoxel Incoherent Motion diffusion MR threshold b-value selection for separating perfusion and diffusion compartments and liver fibrosis diagnostic performance

PurposeTo explore how the selection of threshold b-value impacts Intravoxel Incoherent Motion (IVIM) diffusion parameters of PF (f), Dslow (D),and Dfast (D*) values and their performance for liver fibrosis detection.Materials and MethodsFifteen healthy volunteers and 33 hepatitis-b patients were included. With a 1.5 T MR scanner and respiration gating, IVIM data was acquired with 10 b-values of 10,20,40,60,80,100,150, 200, 400, and 800 s/mm2. Signal measurement was performed on right liver. Segmented-unconstrained analysis was used to compute IVIM parameters, and six threshold b-values between 40 and 200 s/mm2 were compared. PF, Dslow, and Dfast values were placed along the x-axis, y-axis, and z-axis, and a plane was defined to separate volunteers from patients.ResultsHigher threshold b-values were associated with higher PF measurement; while lower threshold b-values led to higher Dslow and Dfast measurements. The dependence of PF, Dslow, and Dfast on threshold b-value differed between healthy livers and fibrotic livers; with the healthy livers showing a higher dependence. Threshold b-value=60 s/mm2 showed the largest mean distance between healthy liver datapoints vs. fibrotic liver datapoints in 3-dimensional space.ConclusionFor segmented-unconstrained analysis, the selection of threshold b-value=60 s/mm2 improves IVIM diffusion differentiation between healthy livers and fibrotic livers.