High-frequency ultrasound imaging was used to evaluate the intestinal walls of the duodenum and colon in patients with intestinal parasitic infections. Ultrasound images were obtained from 100 consecutive patients with symptomatic intestinal parasitic diseases and 40 healthy controls. High-frequency annular array transducer of 7.5 MHz was used to obtain B-mode ultrasound gray-scale and color images of the duodenum and colon with and without water contrast. The diagnosis of parasitic infections was based on clinical presentation, serial stool microscopy, and finding of parasites in duodenal aspirates. We demonstrated normal duodenum and colon echoanatomy in control subjects. In patients with giardiasis, the lesions of the duodenum and colon were associated with increased dimensions and wall thickness compared to healthy controls (p < 0.05). The ultrasound features of giardial lesions were characterized by increased wall echogenicity, flattening or loss of duodenal folds, and/or colonic haustration, hyperechoic floating foci demonstrating chaotic motility, increased perilesional tissue echogenicity, and altered colonic peristalsis. In amebic lesions there were hyperechoic floating foci with bulk motility. There is loss of wall thickness at amebic ulcer sites or wall thickening at amebic granuloma. Helminths were visualized as large hyperechoic linear or curvilinear foci with serpentine or jolting motility. In conclusion, high-frequency B-mode ultrasound imaging with water contrast demonstrated details of duodenal and colonic echoanatomy in normal subjects and patients with giardiasis.
Part of the book: Essentials of Abdominal Ultrasound
Fourier time-series analysis could be used to segregate changes in the ventral and dorsal streams of the visual system in male and female mice. Color memory processes of long-term potentiation and long-term depression could be identified through spectral analysis. We used small animal positron emission tomography and magnetic resonance imaging (PET/MRI) to measure the accumulation of [18F]fluorodeoxyglucose ([18F]FDG) in the mouse brain during light stimulation with blue and yellow filters compared to darkness condition. The mean standardized uptake values (SUV) of [18F]FDG for each stimulus condition was analyzed using standard Fourier analysis software to derive spectral density estimates for each condition. Spectral peaks were identified as originating from the subcortical region (S-peak) by subcortical long-term potentiation (SLTP) or depression (SLTD), and originating from the cortical region (C-peak) by cortical long-term potentiation (CLTP) or depression (CLTD). Luminance opponency occurred at S-peak by SLTP in the dorsal stream in the left visual cortex in male mice. On the other hand, chromatic opponency occurred by wavelength-differencing at C-peak by CLTP in the cortico-subcortical pathways in the ventral stream in the left visual cortex in male mice. In contrast in female mice, during luminance processing, there was resonance phenomenon at C-peak in the ventral stream in the right visual cortex. Chromatic opponency occurred at S-peak by SLTP in the dorsal stream in the right visual cortex in female mice. Application of Fourier analysis improved spatial and temporal resolutions of conventional fPET/MRI methods. Computation of color processing as a conscious experience has wide range applications in neuroscience and artificial intelligence.
Part of the book: Fourier Transforms