Simultaneous Arterial and Venous Imaging Using 3D Quantitative Parameter Mapping

Figures

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  Fig. 1. Processing flow of proposed method. Multiple quantitative parameter maps and vascular images are obtained by (a) capturing 3D images using pRSGE sequences under multiple imaging conditions, (b) estimating relaxation time, (c) synthesizing arterial images, (d) estimating magnetic susceptibility maps, and (e) generating venous images. pRSGE, partially RF-spoiled gradient echo.

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  Fig. 2. Weight calculation and image calculation processes used for arterial image generation. (I) Weight calculation using previously captured datasets of QPM and TOF images. (II) Arterial-image calculation from the QPM images. QPM, quantitative parameter mapping; TOF, time-of-flight.

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  Fig. 3. Example of image used for weight calculation. (a) TOF image, (b) arterial mask image obtained by binarization of TOF image, and (c–d) first echo images of Nos. 1 and 5 QPM scanned images. (MIP to sagittal plane). MIP, maximum intensity projection; QPM, quantitative parameter mapping; TOF, time-of-flight.

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  Fig. 4. Average pixel values of arteries in each axial slice of each image and map used in weight calculation. (a–e) First echo images of Scans Nos. 1–5. (f) PD map, (g) T1 map, and (h) T2* map. Pixel values were normalized so that mean and variance through entire region including background tissues would become 0 and 1, respectively. Each line represents individual subject. Thick line represents mean value between subjects. Dashed line represents average value over entire target area (equal to 0 because of normalization). PD, proton density; T1, longitudinal relaxation time; T2*, apparent transverse relaxation time.

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  Fig. 5. Standard deviation of artery pixel values in each axial slice of each image and map used for weight calculation. (a–e) First echo images of Scan Nos. 1–5. (f) PD map, (g) T1 map, and (h) T2* map. Each thin line represents standard deviation of individual subject. Dashed line represents average of standard deviations of each subject. Thick line represents standard deviation of average intensity value between subjects. PD, proton density; T1, longitudinal relaxation time; T2*, apparent transverse relaxation time.

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  Fig. 6. Weight calculated for each axial slice. Weights differed depending on slice position.

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  Fig. 7. Quantitative images (axial, coronal, and sagittal slices) and vascular images (MIP to each plane). In each case, artifact-free images were obtained. MIP, maximum intensity projection.

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  Fig. 8. Comparison of arterial images obtained with proposed method and reference TOF method for test subject. (a) Arterial image from proposed method, (b) reference image from TOF method, and (c) histogram of pixel values of image from proposed method in arterial and background regions defined by reference TOF image. (d) ROC curve of pixel values with proposed method between arterial and background regions. AUC of ROC curve was 0.932. AUC, area under the curve; ROC, receiver operating characteristic; TOF, time-of-flight.

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  Fig. 9. Comparison of venous images obtained with proposed method and reference QSM method for test subject. (a) Venous image from proposed method, (b) reference venous image, and (c) histogram of pixel values of image with proposed method in venous and background regions defined by reference venous image. (d) ROC curve of pixel values with proposed method between venous and background regions. AUC of ROC curve was 0.920. AUC, area under the curve; QSM, quantitative susceptibility mapping; ROC, receiver operating characteristic.