PURPOSE: Dual velocity encoding PC-MRI can produce spurious artifacts when using high ratios of velocity encoding values (VENCs), limiting its ability to generate high-quality images across a wide range of encoding velocities. This study aims to propose and compare dual-VENC correction methods for such artifacts. THEORY AND METHODS: Two denoising approaches based on spatiotemporal regularization are proposed and compared with a state-of-the-art method based on sign correction. Accuracy is assessed using simulated data from an aorta and brain aneurysm, as well as 8 two-dimensional (2D) PC-MRI ascending aorta datasets. Two temporal resolutions (30,60) ms and noise levels (9,12) dB are considered, with noise added to the complex magnetization. The error is evaluated with respect to the noise-free measurement in the synthetic case and to the unwrapped image without additional noise in the volunteer datasets. RESULTS: In all studied cases, the proposed methods are more accurate than the Sign Correction technique. Using simulated 2D+T data from the aorta (60 ms, 9 dB), the Dual-VENC (DV) error 0.82±0.07$$ 0.82\pm 0.07 $$ is reduced to: 0.66±0.04$$ 0.66\pm 0.04 $$ (Sign Correction); 0.34±0.04$$ 0.34\pm 0.04 $$ and 0.32±0.04$$ 0.32\pm 0.04 $$ (proposed techniques). The methods are found to be significantly different (p-value <0.05$$ <0.05 $$ ). Importantly, brain aneurysm data revealed that the Sign Correction method is not suitable, as it increases error when the flow is not unidirectional. All three methods improve the accuracy of in vivo data. CONCLUSION: The newly proposed methods outperform the Sign Correction method in improving dual-VENC PC-MRI images. Among them, the approach based on temporal differences has shown the highest accuracy.
- MeSH
- Algorithms * MeSH
- Aorta * diagnostic imaging MeSH
- Artifacts * MeSH
- Phantoms, Imaging MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Intracranial Aneurysm diagnostic imaging MeSH
- Humans MeSH
- Magnetic Resonance Imaging * methods MeSH
- Brain diagnostic imaging MeSH
- Computer Simulation MeSH
- Image Processing, Computer-Assisted * methods MeSH
- Signal-To-Noise Ratio * MeSH
- Reproducibility of Results MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- MeSH
- Image Interpretation, Computer-Assisted methods instrumentation MeSH
- Automation, Laboratory methods instrumentation MeSH
- Microscopy classification methods MeSH
- Drug Discovery * methods MeSH
- High-Throughput Screening Assays methods MeSH
- Combinatorial Chemistry Techniques methods MeSH
- Drug Development methods instrumentation MeSH
- Publication type
- Review MeSH
PURPOSE: Transcranial sonography (TCS) magnetic resonance (MR) fusion imaging and digital image analysis are useful tools for the evaluation of various brain pathologies. This study aimed to compare the echogenicity of predefined brain structures in Huntington's disease (HD) patients and healthy controls by TCS-MR fusion imaging using Virtual Navigator and digitized image analysis. MATERIALS AND METHODS: The echogenicity of the caudate nucleus (CN), substantia nigra (SN), lentiform nucleus (LN), insula, and brainstem raphe (BR) evaluated by TCS-MR fusion imaging using digitized image analysis was compared between 21 HD patients and 23 healthy controls. The cutoff values of echogenicity indices for the CN, LN, insula, and BR with optimal sensitivity and specificity were calculated using receiver operating characteristic analysis. RESULTS: The mean echogenicity indices for the CN (67.0±22.6 vs. 37.9±7.6, p<0.0001), LN (110.7±23.6 vs. 59.7±11.1, p<0.0001), and insula (121.7±39.1 vs. 70.8±23.0, p<0.0001) were significantly higher in HD patients than in healthy controls. In contrast, BR echogenicity (24.8±5.3 vs. 30.1±5.3, p<0.001) was lower in HD patients than in healthy controls. The area under the curve was 90.9%, 95.5%, 84.1%, and 81.8% for the CN, LN, insula, and BR, respectively. The sensitivity and specificity were 86% and 96%, respectively, for the CN and 90% and 100%, respectively, for the LN. CONCLUSION: Increased CN, LN, and insula echogenicity and decreased BR echogenicity are typical findings in HD patients. The high sensitivity and specificity of the CN and LN hyperechogenicity in TCS-MR fusion imaging make them promising diagnostic markers for HD.
- MeSH
- Adult MeSH
- Huntington Disease * diagnostic imaging MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Magnetic Resonance Imaging * methods MeSH
- Brain * diagnostic imaging MeSH
- Cerebral Cortex diagnostic imaging MeSH
- Multimodal Imaging methods MeSH
- Caudate Nucleus diagnostic imaging MeSH
- Image Processing, Computer-Assisted methods MeSH
- Reference Values MeSH
- ROC Curve MeSH
- Aged MeSH
- Sensitivity and Specificity MeSH
- Ultrasonography, Doppler, Transcranial methods MeSH
- User-Computer Interface MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- MeSH
- Respiratory Tract Absorption MeSH
- Diagnostic Techniques, Respiratory System * classification instrumentation MeSH
- Diagnostic Imaging * classification methods instrumentation MeSH
- Image Interpretation, Computer-Assisted methods instrumentation MeSH
- Humans MeSH
- Magnetic Resonance Imaging MeSH
- Respiratory Tract Diseases diagnostic imaging MeSH
- Ultrasonography MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
- MeSH
- Arachnoid Cysts diagnostic imaging MeSH
- Adult MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Meningocele diagnostic imaging MeSH
- Cerebrospinal Fluid * diagnostic imaging MeSH
- Neuroimaging * methods MeSH
- Postoperative Complications diagnostic imaging MeSH
- Treatment Outcome MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Publication type
- Case Reports MeSH
Introduction: Measurement of an- hippocampal area or volume is useful in clinical practice as a supportive aid for diagnosis of Alzheimer's disease. Since it is time-consuming and not simple, it is not being used very often. We present a simplified protocol for hippocampal atrophy evaluation based on a single optimal slice in Alzheimer's disease. Methods: We defined a single optimal slice for hippocampal measurement on brain magnetic resonance imaging (MRI) at the plane where the amygdala disappears and only the hippocampus is present. We compared an absolute area and volume of the hippocampus on this optimal slice between 40 patients with Alzheimer disease and 40 age-, education- and gender-mateched elderly controls. Furthermore, we compared these results with those relative to the size of the brain or the skull: the area of the optimal slice normalized to the area of the brain at anterior commissure and the volume of the hippocampus normalized to the total intracranial volume. Results: Hippocampal areas on the single optimal slice and hippocampal volumes on the left and right in the control group were significantly higher than those in the AD group. Normalized hippocampal areas and volumes on the left and right in the control group were significantly higher compared to the AD group. Absolute hippocampal areas and volumes did not significantly differ from corresponding normalized hippocampal areas as well as normalized hippocampal volumes using comparisons of areas under the receiver operating characteristic curves. Conclusion: The hippocampal area on the well-defined optimal slice of brain MRI can reliably substitute a complicated measurement of the hippocampal volume. Surprisingly, brain or skull normalization of these variables does not add any incremental differentiation between Alzheimer disease patients and controls or give better results.
- MeSH
- Alzheimer Disease diagnostic imaging MeSH
- Hippocampus diagnostic imaging MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Magnetic Resonance Imaging methods MeSH
- Aged MeSH
- Imaging, Three-Dimensional methods MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- MeSH
- Diagnostic Imaging * classification MeSH
- Angiography, Digital Subtraction MeSH
- Child MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Tomography, Emission-Computed, Single-Photon MeSH
- Humans MeSH
- Central Nervous System Diseases * diagnostic imaging MeSH
- Positron-Emission Tomography methods MeSH
- Radiopharmaceuticals MeSH
- Check Tag
- Child MeSH
- Humans MeSH
Even though MRI visualization of white matter lesions is pivotal for the diagnosis and management of multiple sclerosis (MS), the issue of detecting diffuse brain tissue damage beyond the apparent T2-hyperintense lesions continues to spark considerable interest. Motivated by the notion that rotating frame MRI methods are sensitive to slow motional regimes critical for tissue characterization, here we utilized novel imaging protocols of rotating frame MRI on a clinical 3 Tesla platform, including adiabatic longitudinal, T1ρ, and transverse, T2ρ, relaxation methods, and Relaxation Along a Fictitious Field (RAFF) in the rotating frame of rank 4 (RAFF4), in 10 relapsing-remitting multiple sclerosis patients and 10 sex- and age-matched healthy controls. T1ρ, T2ρ and RAFF4 relaxograms extracted from the whole white matter exhibited a significant shift towards longer relaxation time constants in MS patients as compared to controls. T1ρ and RAFF4 detected alterations even when considering only regions of normally appearing white matter (NAWM), while other MRI metrics such as T1w/T2w ratio and diffusion tensor imaging measures failed to find group differences. In addition, RAFF4, T2ρ and, to a lesser extent, T1ρ showed differences in subcortical grey matter structures, mainly hippocampus, whereas no functional changes in this region were detected in resting-state functional MRI metrics. We conclude that rotating frame MRI techniques are exceptionally sensitive methods for the detection of subtle abnormalities not only in NAWM, but also in deep grey matter in MS, where they surpass even highly sensitive measures of functional changes, which are often suggested to precede detectable structural alterations. Such abnormalities are consistent with a wide spectrum of different, but interconnected pathological features of MS, including the loss of neuronal cells and their axons, decreased levels of myelin even in NAWM, and altered iron content.
- MeSH
- White Matter diagnostic imaging pathology MeSH
- Adult MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Magnetic Resonance Imaging methods MeSH
- Brain pathology MeSH
- Neuroimaging methods MeSH
- Cross-Sectional Studies MeSH
- Multiple Sclerosis, Relapsing-Remitting diagnostic imaging pathology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
