| 1. |
- Ahlgren, Åsa Rydén, et al.
(författare)
-
Response of the carotid artery longitudinal motion to submaximal physical activity in healthy humans-Marked changes already at low workload
- 2023
-
Ingår i: Physiological Reports. - : Wiley. - 2051-817X. ; 11:2
-
Tidskriftsartikel (refereegranskat)abstract
- The longitudinal motion of the arterial wall, that is, the displacement of the arterial wall along the artery, parallel to blood flow, is still largely unexplored. The magnitude and nature of putative changes in longitudinal motion of the arterial wall in response to physical activity in humans remain unknown. The aim of this study was therefore to study the longitudinal motion of the carotid artery wall during physical activity in healthy humans. Using in-house developed non-invasive ultrasonic methods, the longitudinal motion of the intima-media complex and the diameter changes of the right common carotid artery (CCA) in 40 healthy volunteers (20 volunteers aged 22-35 years; 20 volunteers aged 55-68 years) were assessed at rest and during submaximal supine bicycle exercise. In a subset of the subjects (n = 18) also intramural shear strain were analyzed. The longitudinal motion of the intima-media complex underwent marked changes in response to physical activity, already at low workload; with most evident a marked increase of the first antegrade displacement (p < 0.001) in early systole. Likewise, the corresponding shear strain also increased significantly (p = 0.004). The increase in longitudinal motion showed significant correlation to increase in blood pressure, but not to blood flow velocity or wall shear stress. In conclusion, physical activity markedly influences the longitudinal motion of the carotid artery wall in healthy humans already at low load. A possible "cushioning" function as well as possible implications for the function of the vasa vasorum, endothelium, and smooth muscle cells and extracellular matrix of the media, are discussed.
|
|
| 2. |
- Bunke, Josefine, et al.
(författare)
-
Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin
- 2021
-
Ingår i: Biomedical Optics Express. - 2156-7085. ; 12:7, s. 4084-4096
-
Tidskriftsartikel (refereegranskat)abstract
- Clinical monitoring of blood oxygen saturation (sO2) is traditionally performed using optical techniques, such as pulse oximetry and diffuse reflectance spectroscopy (DRS), which lack spatial resolution. Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technique that is superior to previous techniques in that it combines optical excitation and acoustic detection, providing a map of chromophore distribution in the tissue. Hitherto, PAI has primarily been used in preclinical studies, and only a few studies have been performed in patients. Its ability to measure sO2 with spatial resolution during local vasoconstriction after adrenaline injection has not yet been investigated. Using PAI and spectral unmixing we characterize the heterogeneous change in sO2 after injecting a local anesthetic containing adrenaline into the dermis on the forearm of seven healthy subjects. In comparison to results obtained using DRS, we highlight contrasting results obtained between the two methods arising due to the so-called ‘window effect’ caused by a reduced blood flow in the superficial vascular plexus. The results demonstrate the importance of spatially resolving sO2 and the ability of PAI to assess the tissue composition in different layers of the skin.
|
|
| 3. |
- Dahlstrand, Ulf, et al.
(författare)
-
Photoacoustic imaging for three-dimensional visualization and delineation of basal cell carcinoma in patients
- 2020
-
Ingår i: Photoacoustics. - : Elsevier BV. - 2213-5979. ; 18
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used to determine the borders of basal cell carcinomas (BCC) preoperatively in order to reduce the need for repeated surgery.Methods: Two- and three-dimensional PA images were obtained by scanning BCCs using 59 wavelengths in the range 680-970 nm. Spectral unmixing was performed to visualize the tumor tissue distribution. Spectral signatures from 38 BCCs and healthy tissue were compared ex vivo.Results and discussion: The PA spectra could be used to differentiate between BCC and healthy tissue ex vivo (p < 0.05). Spectral unmixing provided visualization of the overall architecture of the lesion and its border.Conclusion: PA imaging can be used to differentiate between BCC and healthy tissue and can potentially be used to delineate tumors prior to surgical excision.
|
|
| 4. |
- Erlöv, Tobias, et al.
(författare)
-
A Computer Program for Assessing Histoanatomical Morphometrics in Ultra-High-Frequency Ultrasound Images of the Bowel Wall in Children : Development and Inter-Observer Variability
- 2023
-
Ingår i: Diagnostics. - 2075-4418. ; 13:17
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra-high-frequency ultrasound (UHFUS) has a reported potential to differentiate between aganglionic and ganglionic bowel wall, referred to as histoanatomical differences. A good correlation between histoanatomy and UHFUS of the bowel wall has been proven. In order to perform more precise and objective histoanatomical morphometrics, the main research objective of this study was to develop a computer program for the assessment and automatic calculation of the histoanatomical morphometrics of the bowel wall in UHFUS images. A computer program for UHFUS diagnostics was developed and presented. A user interface was developed in close collaboration between pediatric surgeons and biomedical engineers, to enable interaction with UHFUS images. Images from ex vivo bowel wall samples of 23 children with recto-sigmoid Hirschsprung’s disease were inserted. The program calculated both thickness and amplitudes (image whiteness) within different histoanatomical bowel wall layers. Two observers assessed the images using the program and the inter-observer variability was evaluated. There was an excellent agreement between observers, with an intraclass correlation coefficient range of 0.970–0.998. Bland–Altman plots showed flat and narrow distributions. The mean differences ranged from 0.005 to 0.016 mm in thickness and 0 to 0.7 in amplitude units, corresponding to 1.1–3.6% and 0.0–0.8% from the overall mean. The computer program enables and ensures objective, accurate and time-efficient measurements of histoanatomical thicknesses and amplitudes in UHFUS images of the bowel wall. The program can potentially be used for several bowel wall conditions, accelerating research within UHFUS diagnostics.
|
|
| 5. |
- Erlöv, Tobias, et al.
(författare)
-
Regional motion correction for in vivo photoacoustic imaging in humans using interleaved ultrasound images
- 2021
-
Ingår i: Biomedical Optics Express. - 2156-7085. ; 12:6, s. 3312-3322
-
Tidskriftsartikel (refereegranskat)abstract
- In translation from preclinical to clinical studies using photoacoustic imaging, motion artifacts represent a major issue. In this study the feasibility of an in-house algorithm, referred to as intensity phase tracking (IPT), for regional motion correction of in vivo human photoacoustic (PA) images was demonstrated. The algorithm converts intensity to phase-information and performs 2D phase-tracking on interleaved ultrasound images. The radial artery in eight healthy volunteers was imaged using an ultra-high frequency photoacoustic system. PA images were motion corrected and evaluated based on PA image similarities. Both controlled measurements using a computerized stepping motor and free-hand measurements were evaluated. The results of the controlled measurements show that the tracking corresponded to 97 ± 6% of the actual movement. Overall, the mean square error between PA images decreased by 52 ± 15% and by 43 ± 19% when correcting for controlled- and free-hand induced motions, respectively. The results show that the proposed algorithm could be used for motion correction in photoacoustic imaging in humans.
|
|
| 6. |
- Evertsson, Maria, et al.
(författare)
-
Design of a Pediatric Rectal Ultrasound Probe Intended for Ultra-High Frequency Ultrasound Diagnostics
- 2023
-
Ingår i: Diagnostics. - 2075-4418. ; 13:10
-
Tidskriftsartikel (refereegranskat)abstract
- It has been shown that ultra-high frequency (UHF) ultrasound applied to the external bowel wall can delineate the histo-anatomic layers in detail and distinguish normal bowel from aganglionosis. This would potentially reduce or lessen the need for biopsies that are currently mandatory for the diagnosis of Hirschsprung’s disease. However, to our knowledge, no suitable rectal probes for such a use are on the market. The aim was to define the specifications of an UHF transrectal ultrasound probe (50 MHz center frequency) suitable for use in infants. Probe requirements according to patient anatomy, clinicians’ requests, and biomedical engineering UHF prerequisites were collected within an expert group. Suitable probes on the market and in clinical use were reviewed. The requirements were transferred into the sketching of potential UHF ultrasound transrectal probes followed by their 3D prototype printing. Two prototypes were created and tested by five pediatric surgeons. The larger and straight 8 mm head and shaft probe was preferred as it facilitated stability, ease of anal insertion, and possible UHF technique including 128 piezoelectric elements in a linear array. We hereby present the procedure and considerations behind the development of a proposed new UHF transrectal pediatric probe. Such a device can open new possibilities for the diagnostics of pediatric anorectal conditions.
|
|
| 7. |
- Graneli, Christina, et al.
(författare)
-
Histopathological dimensions differ between aganglionic and ganglionic bowel wall in children with Hirschsprung’s disease
- 2022
-
Ingår i: BMC Pediatrics. - : Springer Science and Business Media LLC. - 1471-2431. ; 22
-
Tidskriftsartikel (refereegranskat)abstract
- Background: In the validation of new imaging technology for children with Hirschsprung’s disease (HSCR), basic anatomical parameters of the bowel wall must be established specifically for this patient group. Aim: To explore differences in histoanatomical layers of bowel wall, comparing ganglionic and aganglionic bowel walls, and to examine if the bowel wall thickness is linked to patient weight. Methods: This was an observational study of bowel specimens from children weighing 0–10 kg, operated on consecutively during 2018–2020. Ganglionic and aganglionic bowel walls were measured in digitalized microscopy images from 10 sites per trans-sectional specimen and compared regarding the thickness of their histoanatomical layers. Results: Bowel walls were measured in 21 children. Full bowel wall thickness did not differ between aganglionic and ganglionic bowel (2.20 vs 2.04; p = 0.802) while weight at surgery correlated positively with both ganglionic and aganglionic bowel wall thickness (r = 0.688 and 0.849, respectively), and age at surgery with ganglionic bowel wall thickness (r = 0.517). In aganglionic segments, the muscularis externa layer was thicker compared to that in ganglionosis (0.45 vs 0.31 mm, p = 0.012) whereas the muscularis interna was thinner (0.45 vs 0.62 mm, p < 0.001). A diagnostic index was identified whereby a lower ratio of muscularis interna/externa thickness followed by a thinner muscularis interna differed between aganglionic and ganglionic bowel in all specimens. Conclusion: Thicknesses of the bowel wall’s muscle layers differ between aganglionic and ganglionic bowel walls in children with HSCR. These findings support a diagnostic index that could be validated for transfer to instant diagnostic imaging techniques.
|
|
| 8. |
- Granéli, Christina, et al.
(författare)
-
Ultra high frequency ultrasonography to distinguish ganglionic from aganglionic bowel wall in Hirschsprung disease : A first report
- 2021
-
Ingår i: Journal of Pediatric Surgery. - : Elsevier BV. - 0022-3468. ; 56:12, s. 2281-2285
-
Tidskriftsartikel (refereegranskat)abstract
- Background/Purpose: In Hirschsprung disease (HD) surgery, confirming ganglionic bowel is essential. A faster diagnostic method than the current frozen biopsy is desirable. This study investigated whether aganglionic and ganglionic intestinal wall can be distinguished from each other by ultra high frequency ultrasound (UHF ultrasound). Methods: In an HD center during 2019, intestinal walls of recto-sigmoid specimens from HD patients were examined ex vivo with a 70 MHz UHF ultrasound transducer. Data from four sites were described. Histopathologic analysis was compared to the ultrasonography outcome at each site. Each patient's specimen served as its own control. Results: 11 resected recto-sigmoid specimens (median 20 cm long [range 6.5–33]) with transition zones of 5 cm (2–11 cm) were taken from children aged 22 days (13–48) weighing 3668 g (3500–5508); 44 key sites were analyzed. There was full concordance for 42/44 (95%) key sites and 10 of 11 (91%) specimens. The specimen with discordance of two key sites contained a segment of aganglionosis (3 cm) and a transition zone (1 cm): the site discordance was limited to the transition zone ends. Conclusions: This first report on UHF ultrasound in recto-sigmoid HD shows promising results in identifying aganglionosis, transition zones and ganglionic bowel. Further in vivo studies are required.
|
|
| 9. |
- Hawez, Tebin, et al.
(författare)
-
Ultra-High Frequency Ultrasound Imaging of Bowel Wall in Hirschsprung’s Disease—Correlation and Agreement Analyses of Histoanatomy
- 2023
-
Ingår i: Diagnostics. - 2075-4418. ; 13:8
-
Tidskriftsartikel (refereegranskat)abstract
- Hirschsprung’s disease (HD) is characterized by aganglionosis in the bowel wall, requiring resection. Ultra-high frequency ultrasound (UHFUS) imaging of the bowel wall has been suggested to be an instantaneous method of deciding resection length. The aim of this study was to validate UHFUS imaging of the bowel wall in children with HD by exploring the correlation and systematic differences between UHFUS and histopathology. Resected fresh bowel specimens of children 0–1 years old, operated on for rectosigmoid aganglionosis at a national HD center 2018–2021, were examined ex vivo with UHFUS center frequency 50 MHz. Aganglionosis and ganglionosis were confirmed by histopathological staining and immunohistochemistry. Histoanatomical layers of bowel wall in histopathological and UHFUS images, respectively, were outlined using MATLAB programs. Both histopathological and UHFUS images were available for 19 aganglionic and 18 ganglionic specimens. The thickness of muscularis interna correlated positively between histopathology and UHFUS in both aganglionosis (R = 0.651, p = 0.003) and ganglionosis (R = 0.534, p = 0.023). The muscularis interna was systematically thicker in histopathology than in UHFUS images in both aganglionosis (0.499 vs. 0.309 mm; p < 0.001) and ganglionosis (0.644 versus 0.556 mm; p = 0.003). Significant correlations and systematic differences between histopathological and UHFUS images support the hypothesis that UHFUS reproduces the histoanatomy of the bowel wall in HD accurately.
|
|
| 10. |
|
|
