Caption: Figure 2: Signal-to-noise ratios and contrast-to-noise ratios in the first-pass MR angiography (TWIST) following the administration of the elastin-specific molecular agent and the clinically used agent gadobutrol.
Caption: Figure 4: Signal-to-noise ratios and contrast-to-noise ratios in the high-resolution 3D angiography (FLASH) following the administration of the elastin-specific molecular agent and the clinically used agent gadobutrol.
SNR-A was the contrast-to-noise ratio
of the irradiated portion of the phantom and SNR-B was the non-radiated part.
Image quality evaluation studies of CR systems typically use metrics such as contrast-to-noise ratios
(CNRs), limiting spatial resolution, the modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE).
Digora VistaScan Megadixel Sensor type PSP PSP CCD Size (mm) 41 x 31 39 x 28 30 x 20 Matrix size 640 x 484 787 x 553 1500 x 1000 Pixel size (mm) 0.064 0.05 0.02 Image format DICOM DICOM DICOM Input Gray level (bits) 14 16 14 Output Gray level (bits) 8 16 8 Table 2: Contrast-to-noise ratio
for each detector.
(9,10) In a study of 93 patients, Zhang et al (10) showed that focal hepatic lesions had similar CT-density measurements and contrast-to-noise ratios
on virtual unenhanced and true unenhanced images.
Image quality of TNC, VNCa, VNCv, and VNCe images, contrast-to-noise ratio (CNR) of metastasis in relation to the liver parenchyma, and metastasis detection rate were evaluated and analyzed.
Contrast-to-noise ratio of metastasis-to-liver was calculated as following: [sup],
Quantitative analysis was performed by comparison of mean aortic attenuation, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR).
d) contrast-to-noise ratio (CNR), calculated as the difference between the mean attenuation of the artery and the mean attenuation of the muscle, divided by image noise:
A potential limitation of 3D GE imaging is a diminished contrast-to-noise ratio
. This has led to concern regarding the use of this technique other than for gadolinium-enhanced fat-suppressed interstitial-phase imaging, in which the gadolinium effectively improves the contrast-to-noise ratio
Steady-state sequences are faster, and have higher SNRs and contrast-to-noise ratios
. With a spoiled sequence, the "bright blood" comes from through plane-flow enhancement (similar to time-of-flight angiography).