Structural Optical Coherence Tomography Images Research Articles

Presumed Müller Cell Activation in Multiple Evanescent White Dot Syndrome.

The purpose of this study was to investigate the foveal changes occurring in multiple evanescent white dot syndrome (MEWDS) using multimodal imaging techniques with a specific focus on hyper-reflective dots (HRDs). This was a retro-prospective observational study including 35 eyes with active MEWDS. Structural and en face optical coherence tomography (OCT) was performed, with follow-up visits at 2 weeks, 6 weeks, and 2 months from baseline. HRD percentage area (HRD % area) was calculated in a 600 µm fovea centered circle on en face OCT, after background subtraction and image binarization. HRD % area was compared with 23 fellow control eyes. Longitudinal changes in the HRD % areas were assessed using repeated-measure statistics. HRDs were observed as scattered hyper-reflective spots on the vitreoretinal interface on en face OCT images, colocalizing with HRDs or vertical hyper-reflective lines on structural OCT images. The baseline evaluation showed a significantly higher HRD % area in MEWDS eyes compared to fellow eyes (0.10 ± 0.03 vs. 0.08 ± 0.04, P = 0.01). The HRD% area correlated positively with LogMAR visual acuity and inversely with the duration of symptoms. Longitudinal analysis revealed a significant reduction in the HRD % area over time. There was no significant interaction between the rate of HRD disappearance and clinical or demographic factors at baseline. As HRD potentially represents the end-feet projections of activated Müller cells on the retinal surface, this study supports the involvement of Müller cells in the pathogenesis of the disease. The findings highlight the potential of en face OCT imaging for monitoring the progression of MEWDS.

Quantification of linear and nonlinear elasticity by compression optical coherence elastography for determining lymph node status in breast cancer

We report the first application of compression optical coherence elastography (C-OCE) to evaluate both linear and nonlinear elastic properties of lymph nodes (LNs) for assessing their status, which is an important factor for detecting metastasis and staging breast cancer. The reported study involved 27 excised sentinel and axillary LNs from 24 patients with breast cancer, including normal LNs (n = 6), reactive LNs with follicular hyperplasia (n = 7) and sinus histiocytosis (n = 8), and metastatic LNs (n = 6). C-OCE data were compared with co-registered gold-standard histopathology and demonstrated a significantly higher contrast in differentiation of LNs as compared to structural optical coherence tomography imaging. Normal LNs are characterized by low stiffness values in the areas of LN cortex (<200 kPa). C-OCE revealed that abnormal reactive LNs with follicular hyperplasia exhibit moderately increased stiffness (200–300 kPa) in the cortex areas and more pronounced stiffness increase (400–600 kPa) in the areas of sinus histiocytosis. LNs with total metastasis exhibit fairly uniformly distributed highest stiffness values (>600 kPa). Since in terms of the tangent Young’s modulus there remained an appreciable overlap among these types of LNs, we also evaluated their elastic nonlinearity parameters. Complementary usage of both linear and nonlinear elastic parameters enabled very clear differentiation of all four main states of LNs. Thus, C-OCE imaging demonstrates high potential for future intraoperative usage to rapidly determine the LN status during breast-conserving surgery and to assess the extent of the cancer cells propagation in regional lymphatic collectors for preserving benign LNs. This is important for reducing the associated risks and complications (such as lymphedema) from excessive surgical removal of lymphoid structures.

Nondestructive label-free detection of peritumoral white matter damage using cross-polarization optical coherence tomography

To improve the quality of brain tumor resections, it is important to differentiate zones with myelinated fibers destruction from tumor tissue and normal white matter. Optical coherence tomography (OCT) is a promising tool for brain tissue visualization and in the present study, we demonstrate the ability of cross-polarization (CP) OCT to detect damaged white matter and differentiate it from normal and tumor tissues. The study was performed on 215 samples of brain tissue obtained from 57 patients with brain tumors. The analysis of the obtained OCT data included three stages: 1) visual analysis of structural OCT images; 2) quantitative assessment based on attenuation coefficients estimation in co- and cross-polarizations; 3) building of color-coded maps with subsequent visual analysis. The defining characteristics of structural CP OCT images and color-coded maps were determined for each studied tissue type, and then two classification tests were passed by 8 blinded respondents after a training. Visual assessment of structural CP OCT images allows detecting white matter areas with damaged myelinated fibers and differentiate them from normal white matter and tumor tissue. Attenuation coefficients also allow distinguishing all studied brain tissue types, while it was found that damage to myelinated fibers leads to a statistically significant decrease in the values of attenuation coefficients compared to normal white matter. Nevertheless, the use of color-coded optical maps looks more promising as it combines the objectivity of optical coefficient and clarity of the visual assessment, which leads to the increase of the diagnostic accuracy of the method compared to visual analysis of structural OCT images. Alteration of myelinated fibers causes changes in the scattering properties of the white matter, which gets reflected in the nature of the received CP OCT signal. Visual assessment of structural CP OCT images and color-coded maps allows differentiating studied tissue types from each other, while usage of color-coded maps demonstrates higher diagnostic accuracy values in comparison with structural images (F-score = 0.85-0.86 and 0.81, respectively). Thus, the results of the study confirm the potential of using OCT as a neuronavigation tool during resections of brain tumors.

Artificial Intelligence for the Diagnosis and Screening of Retinal Diseases

Artificial intelligence (AI) is becoming established as a new method for analysing ophthalmological data, and unveiling new clinical and pathogenic insights into retinal diseases. AI-based algorithms are largely employed in the field of the most prevalent retinal diseases, including diabetic retinopathy, age-related macular degeneration and myopia. Several research groups are also testing AI in other retinal diseases, including inherited retinal dystrophies, retinopathy of prematurity, central serous chorioretinopathy and retinal vein occlusion. AI models are mainly used in screening of the fundus and structural optical coherence tomography images. However, more advanced methodologies are under investigation to extract clinically relevant information regarding the biomarkers of disease activity and outcome measures. AI is a powerful tool for increasing the amount of information obtained in clinical and research contexts. However, many issues still need addressing, including the resulting high demand for technology and resources, and the need for very large databases. Moreover, several ethical issues require debate, and specific rules are needed to govern the use of AI algorithms and check the quality of the analysed data. This article reviews the current use of AI in retinal diseases, unmet needs and future perspectives.

Quantitative compressive optical coherence elastography using structural OCT imaging and optical palpation to measure soft contact lens mechanical properties.

In this study, the principle of 'optical palpation' was applied to a compression optical coherence elastography (OCE) method using spectral domain optical coherence tomography (OCT). Optical palpation utilizes a compliant transparent material of known mechanical properties, which acts as a stress sensor, in order to derive the mechanical properties of a sample material under examination. This technique was applied to determine the mechanical properties of soft contact lenses, with one lens being used as the compliant stress sensor and the other as the sample under investigation to extract the mechanical properties. This compliant stress sensor allowed for the stress of the compression to be measured without the use of a force sensor. The strain of the materials was measured through an automatic boundary segmentation that tracks the material thickness (of the sensor and the sample) during compression through sequential structural OCT images. A total of five contact lens combinations were tested, using three separate commercially available contact lenses with unique mechanical properties. Various combinations of contact lens materials were used to further validate the technique. The Young's modulus derived from this method was compared to nominal manufacturer's values. Both accuracy and repeatability were assessed, with highly accurate measurements obtained, with a percentage difference between the nominal and experimentally derived Young's modulus being less than 6% for all the tested combinations as well as providing a Young's modulus that was not statistically significant different (p > 0.01) to the nominal value. The results demonstrate the potential of optical palpation in OCE to accurately measure the mechanical properties of a material without the use of sophisticated electronics to capture the stress of the sample. These findings have potential to be translated into a method for tissue mechanical testing with ex vivo and in vivo clinical applications.

Time-encoded mid-infrared Fourier-domain optical coherence tomography.

We report on a technically simple approach to achieve high-resolution and high-sensitivity Fourier-domain optical coherence tomography (OCT) imaging in the mid-infrared (mid-IR) range. The proposed OCT system employs an InF3 supercontinuum source. A specially designed dispersive scanning spectrometer based on a single InAsSb point detector is employed for detection. The spectrometer enables structural OCT imaging in the spectral range from 3140 nm to 4190 nm with a characteristic sensitivity of over 80 dB and an axial resolution below 8µm. The capabilities of the system are demonstrated for imaging of porous ceramic samples and transition-stage green parts fabricated using an emerging method of lithography-based ceramic manufacturing. Additionally, we demonstrate the performance and flexibility of the system by OCT imaging using an inexpensive low-power (average power of 16 mW above 3µm wavelength) mid-IR supercontinuum source.

Quantitative characterization of human breast tissue based on deep learning segmentation of 3D optical coherence tomography images.

In this study, we performed dual-modality optical coherence tomography (OCT) characterization (volumetric OCT imaging and quantitative optical coherence elastography) on human breast tissue specimens. We trained and validated a U-Net for automatic image segmentation. Our results demonstrated that U-Net segmentation can be used to assist clinical diagnosis for breast cancer, and is a powerful enabling tool to advance our understanding of the characteristics for breast tissue. Based on the results obtained from U-Net segmentation of 3D OCT images, we demonstrated significant morphological heterogeneity in small breast specimens acquired through diagnostic biopsy. We also found that breast specimens affected by different pathologies had different structural characteristics. By correlating U-Net analysis of structural OCT images with mechanical measurement provided by quantitative optical coherence elastography, we showed that the change of mechanical properties in breast tissue is not directly due to the change in the amount of dense or porous tissue.

Online measurement of floc size, viscosity, and consistency of cellulose microfibril suspensions with optical coherence tomography

In this study, cellulose microfibril (CMF) suspensions were imaged during pipe flow at consistencies of 0.4%, 1.0%, and 1.6% with optical coherence tomography (OCT) to obtain images of the structure and the local velocity of the suspension. The viscosities obtained by combining pressure loss measurement with the OCT velocity data showed typical shear thinning behavior and were in excellent agreement with viscosities obtained with ultrasound velocity profiling. The structural OCT images were used to calculate the radial and the axial floc sizes of the suspension. A fit of power law to the geometrical floc size–shear stress data gave the same power law index for all consistencies, suggesting that floc rupture dynamics is independent of consistency. The dependence of viscosity and floc size on shear stress was similar, indicating that the shear thinning behavior of CMF suspensions is closely related to the rupture dynamics of flocs. The results also showed that an apparent attenuation coefficient of the OCT signal can be used to determine the consistency of CMF suspensions.

Vitreomacular traction quantitative cutoffs for the assessment of resolution after ocriplasmin intravitreal treatment

This study aimed to assess optical coherence tomography (OCT) parameters associated with vitreomacular traction (VMT) resolution after ocriplasmin intravitreal injection and also associated with the development of vitreomacular complications. Study designed was a retrospective case series. Structural OCT images were acquired at baseline and over the follow-up after treatment. We developed a mathematical model to provide quantitative parameters associated with VMT resolution. Moreover, we adopted the same model to assess the quantitative parameters associated with development of further vitreomacular complications or with the worsening of the coexisting condition. Main outcome measures were BCVA, central macular thickness (CMT), VMT reflectivity, VMT size, VMT resolution, epiretinal membrane (ERM), macular holes. 73 eyes of 73 VMT patients (mean age 73 ± 9 years) were recruited. The mean follow-up duration was 2.6 ± 1.1 years. Mean baseline BCVA was 0.38 ± 0.18 LogMAR, improving to 0.26 ± 0.20 at the end of the follow-up (p < 0.01). Baseline CMT was 431 ± 118 µm, improving to 393 ± 122 µm at the end of the follow-up (p < 0.01). 38/73 eyes (52%) showed only VMT, whereas 35/73 eyes (48%) also showed coexisting alterations at baseline. VMT resolved in 40/73 eyes (55% of cases). Our model disclosed VMT reflectivity as the most involved parameter in VMT resolution. VMT size showed less influence on the success of ocriplasmin treatment. ERM was negatively associated with VMT resolution. Moreover, VMT reflectivity values and ERM represented the most important parameters for the onset of vitreomacular complications.

VARYING OPTICAL COHERENCE TOMOGRAPHY APPEARANCE OF THE INNER CHOROID WITH AGE: Possible Explanation and Histologic Correlate.

To investigate the reflectivity of the structural optical coherence tomography images of the inner choroid as it relates to potential structural composition. The reflectivity of slab images 29 to 49 µm and 45 to 65 µm below the retinal pigment epithelium, obtained with the Zeiss Plex Elite 9000, was evaluated. The mean and SD of a group of subjects with no ocular disorders were determined. Binarization of the images was performed and a threshold level established at the mean plus one SD for each slab depth. The proportion of area binarized was evaluated with generalized estimating equations. Representative histologic images obtained from autopsy donors were stained with Masson's trichrome, a staining method helpful in evaluating collagen and ground substance of tissue. There were 67 eyes of 38 subjects with a mean age of 44.5 (range 22-82) years. Using generalized estimating equations, age was found to be a significant predictor for the proportion of binarized pixels in both the 29 to 49 µm (P = 0.034) and the 45 to 65 µm (P < 0.001) slabs. The histologic specimens illustrated the loss of ground substance with increasing compaction of collagen fibers in the choroidal stroma with advancing age. The reflectivity from the inner choroid is not uniform and changes with age. As suggested by the histologic specimens, we propose the optical coherence tomography reflectance from the inner choroid is related, in part, to the packing density of collagen fibers present there.

Preservation of the Foveal Avascular Zone in Achromatopsia Despite the Absence of a Fully Formed Pit.

PurposeTo examine the foveal avascular zone (FAZ) in patients with congenital achromatopsia (ACHM).MethodsForty-two patients with genetically confirmed ACHM were imaged either with Optovue's AngioVue system or Zeiss's Plex Elite 9000, and the presence or absence of a FAZ was determined. For images where a FAZ was present and could be confidently segmented, FAZ area, circularity index, and roundness were measured and compared with previously published normative values. Structural optical coherence tomography images were acquired to assess the degree of foveal hypoplasia (number and thickness of inner retinal layers present at the fovea).ResultsA FAZ was present in 31 of 42 patients imaged (74%), although no determination could be made for 11 patients due to poor image quality (26%). The mean ± SD FAZ area for the ACHM retina was 0.281 ± 0.112 mm2, which was not significantly different from the previously published normative values (P = 0.94). However, their FAZs had decreased circularity (P < 0.0001) and decreased roundness (P < 0.0001) compared to the normative cohort. In the patients with ACHM examined here, the FAZ area decreased as the number and thickness of the retained inner retinal layers increased.ConclusionsOur data demonstrate that despite the presence of foveal hypoplasia, patients with ACHM can have a FAZ. This is distinct from other conditions associated with foveal hypoplasia, which generally show an absence of the FAZ. In ACHM, FAZ formation does not appear to be sufficient for complete pit formation, contrary to some models of foveal development.

PREDICTIVE ACTIVATION BIOMARKERS OF TREATMENT-NAIVE ASYMPTOMATIC CHOROIDAL NEOVASCULARIZATION IN AGE-RELATED MACULAR DEGENERATION.

To assess the long-term evolution of treatment-naive quiescent choroidal neovascularization (CNV), in age-related macular degeneration (AMD), to identify predictive activation biomarkers. Patients with quiescent CNV underwent a comprehensive ophthalmological examination, including fluorescein and indocyanine green angiographies, structural optical coherence tomography (OCT), and OCT angiography. Qualitative and quantitative analyses of structural OCT and OCT angiography images were performed during the study period. At the last follow-up evaluation, the enrolled eyes were divided into two groups: eyes with quiescent CNV converting to exudative AMD (eAMD) and those not progressing to eAMD. Sixty-eight eyes of 68 patients were enrolled in the study. Mean follow-up duration was 40 ± 28 months using multimodal imaging and 22 ± 13 months using OCT angiography. On structural OCT, quiescent CNV not converting to eAMD showed a preferential growth of the pigment epithelium detachment greatest linear diameter (P = 0.009), whereas the eAMD group presented a preferential growth of the pigment epithelium detachment maximal height (P < 0.0001) during the study period. Quantitative analysis of choriocapillaris OCT angiograms confirmed the CNV area growth during follow-up (from 4.18 ± 4.77 mm at baseline to 5.10 ± 5.06 mm at the last follow-up visit; P = 0.02). A close follow-up is recommended to early identify predictive activation biomarkers of treatment-naive quiescent CNV.

Choroidal luminal and stromal areas and choriocapillaris perfusion are characterised by a non-linear quadratic relation in healthy eyes

PurposeTo assess the associations among different optical coherence tomography (OCT) structural and angiography quantitative metrics used to characterise the choroid in healthy subjects.MethodsIn this cross-sectional study, macular structural OCT and...

Visualization of Anatomical Structures of Biological Tissues by Optical Coherence Tomography with Digital Processing of Morphological Data

A new method for reducing the general level of speckle noise in optical coherence tomography (OCT) structural images is described. The suggested approach is based on a combination of multilevel multipurpose filtering and cyclical morphological processing of interference signals. It involves repeatedly applied morphological erosion of speckle patterns and morphological dilation of the remaining parts of the structural OCT image. The suggested approach can be used in optical coherence elastography to determine control points in structural OCT images before and after the deforming action.

Clinical Corneal Optical Coherence Elastography Measurement Precision: Effect of Heartbeat and Respiration.

PurposeNormal physiological movements (e.g., respiration and heartbeat) induce eye motions during clinical measurements of human corneal biomechanical properties using optical coherence elastography (OCE). We quantified the effects of respiratory and cardiac-induced eye motions on clinical corneal OCE measurement precision and repeatability.MethodsCorneal OCE was performed using low-force, micro-air-pulse tissue stimulation and high-resolution phase-sensitive optical coherence tomography (OCT) imaging. Axial surface displacements of the corneal apex were measured (M-mode) at a 70-kHz sampling rate and three different stimulation pressures (20–60 Pa). Simultaneously, the axial corneal position was tracked with structural OCT imaging, while the heartrate and respiration were monitored over a 90 second period.ResultsRespiratory- and cardiac-induced eye motions have distinctly lower frequency (0.1–1 Hz) and much greater amplitude (up to ± 50 µm movements) than air-pulse-induced corneal tissue deformations (∼250 Hz, <1 µm). The corneal displacements induced during OCE measurements in vivo were –0.41 ± 0.06 µm (n = 22 measurements, coefficient of variation [CV]: 14.6%) and –0.44 ± 0.07 µm (n = 50 measurements, CV: 15.9%), respectively, from two human subjects at 40 Pa stimulation pressure. Observed variation in corneal tissue displacements were not associated with tissue stimulation magnitude, or the amplitude of physiologically induced axial eye motion.ConclusionsThe microsecond timescale and submicron tissue displacements observed during corneal OCE measurements are separable from normal involuntary physiological movements, such as the oculocardiac pulse and respiratory movements.Translational RelevanceThis work advances innovations in biomedical imaging and engineering for clinical diagnostic applications for soft-tissue biomechanical testing.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES OF FOCAL CHOROIDAL EXCAVATION AND THE CHOROIDAL STROMA VARIATIONS WITH OCCURRENCE OF EXCAVATION

To describe retinal and choroidal vascular changes, and choroidal stroma variations occurring in focal choroidal excavation (FCE). Study design was a cross-sectional case series. Consecutive patients affected by FCE and healthy controls were recruited. All patients underwent complete ophthalmologic assessment and multimodal imaging, including structural optical coherence tomography and optical coherence tomography angiography. Choroidal thickness and stromal index were calculated from structural optical coherence tomography images. Moreover, we measured vessel density values of the superficial capillary plexus, deep capillary plexus and choriocapillaris at the level of the macula. Twenty-two patients (28 eyes; mean age 57.2 ± 16.4) and 28 control eyes (mean age of 56.5 ± 9.8) were included. Five patients (23%) were asymptomatic, whereas 17 patients (77%) complained of visual symptoms. FCE was associated with choroidal neovascularization in 10 eyes (35%). Choroidal stromal component was lower in FCE patients than controls, whereas choroidal thickness was unremarkable. Stromal index values calculated in the region proximal to the FCE was significantly lower than the values obtained from the external region. Deep capillary plexus vessel density was lower in FCE than controls. Choriocapillaris was altered in the region surrounding the FCE, whereas it was normal in the external region. Deep capillary plexus and choriocapillaris plexus were significantly altered in FCE patients. Moreover, choroidal stroma was significantly reduced in the areas closer to FCE compared to the surrounding choroid in patients, as well as compared to healthy controls, suggesting the hypothesis of weakening of the architectural support, creating a more friable point, which can favor FCE development.

OCTA-Based Identification of Different Vascular Patterns in Stargardt Disease.

PurposeThe aim of the present study was to analyze quantitative optical coherence tomography (OCT) and OCT angiography (OCTA) parameters to identify clinically relevant cutoff values able to detect clinically different Stargardt's disease (STGD) subgroups.MethodsConsecutive STGD patients were recruited and underwent complete ophthalmologic examination, including multimodal imaging. Several quantitative parameters were extracted both from structural OCT and OCTA images and were statistically analyzed. A post hoc analysis was performed to identify a quantitative cutoff able to distinguish two clinically different STGD subgroups. Main outcome measures were total retinal thickness, central macular thickness (CMT), retinal layers thickness, retinal and choroidal hyperreflective foci (HF) number, vessel density (VD), vessel tortuosity (VT), vessel dispersion (Vdisp), and vessel rarefaction (VR) of macular and optic nerve head plexa.ResultsOverall, 54 eyes of 54 STGD patients (18 males) and 54 eyes of 54 healthy age- and sex-matched controls were included in the analysis. All quantitative parameters resulted significantly worse in STGD than controls (P < 0.01). Moreover, a VT cutoff of 5 allowed to distinguish the following two categories: a functionally and anatomically better STGD group and a worse group. BCVA resulted 0.42 ± 0.28 logMAR in the best group versus 1.09 ± 0.36 logMAR in the worst (P < 0.01). Structural OCT and OCTA parameters significantly differed between the two STGD groups.ConclusionsQuantitative OCTA was able to detect different morphofunctional STGD phenotypes.Translational RelevanceOCTA-based classification of STGD patients detected different patients' subgroups, differing in terms of morphologic and functional features, with a potential impact on clinical and research settings.

En Face OCT of Type 2 Neovascularization:A Reappraisal of the Pitchfork Sign.

To describe a new en face optical coherence tomography (OCT) imaging feature of type 2 choroidal neovascularization (CNV) and illustrate the OCT angiographic (OCTA) findings in these eyes. Multimodal images of patients with type 2 CNV who displayed the typical "pitchfork" sign with cross-sectional OCT were reviewed. Corresponding en face structural OCT and OCTA images were analyzed to correlate the finding before and after anti-vascular endothelial growth factor (VEGF) therapy. Five eyes of five patients, including two females and three males with a median age of 13 years (range: 8 years to 84 years), were studied. The etiology for type 2 CNV was laser-induced maculopathy in two eyes, idiopathic in two eyes, and age-related macular degeneration in one eye. None of the eyes had evidence of inflammatory ocular disease. En face OCT displayed a characteristic wreath-like pattern of hyperreflective spikes surrounding the type 2 neovascular membrane that originated from the ellipsoid zone and extended into the outer nuclear layer. Wreath-like spikes resolved with intravitreal anti-VEGF injection with good visual outcomes and transformation of the neovascular lesion from a type 2 to type 1 morphology. Type 2 CNV associated with the pitchfork sign with cross-sectional OCT displayed a characteristic wreath-like pattern of hyperreflective spikes with en face OCT that resolved with anti-VEGF therapy. This form of type 2 neovascularization may occur in eyes with different underlying etiologies and without signs of intraocular inflammation and is not limited to pediatric patients. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:719-725.].

Optical coefficients as tools for increasing the optical coherence tomography contrast for normal brain visualization and glioblastoma detection

The methods used for digital processing of optical coherence tomography (OCT) and crosspolarization (CP) OCT images are focused on improving the contrast ratio of native structural OCT images. Such advances are particularly important for the intraoperative detection of glioma margins where the visual assessment of OCT images can be difficult and lead to errors. The aim of the study was to investigate the application of optical coefficients obtained from CP OCT data for the differentiation of glial tumorous tissue from a normal brain. Pseudocolor en-face OCT maps based on two optical coefficients (the commonly used rate of attenuation in the cochannel, and in addition, the interchannel attenuation difference) were constructed for normal rat brain coronal cross sections and for brains with a 101.8 rat glioblastoma model. It was shown that the use of optical coefficients significantly increased the available information from the OCT data in comparison with unprocessed images. As a result, this allowed contrasting of the white matter from the gray matter and tumorous tissue ex vivo, and for this purpose, the interchannel attenuation difference worked better. The interchannel attenuation difference values of white matter were at least seven and two times higher than corresponding values of the cortex and tumorous tissue, whereas the same parameter for cochannel attenuation coefficient values of white matter are about 4 and 1.4. However, quantitative analysis shows that both coefficients are suitable for the purpose of glioblastoma detection from normal brain tissue regardless of whether a necrotic component was present (in all compared groups ).

Generating retinal flow maps from structural optical coherence tomography with artificial intelligence

Despite advances in artificial intelligence (AI), its application in medical imaging has been burdened and limited by expert-generated labels. We used images from optical coherence tomography angiography (OCTA), a relatively new imaging modality that measures retinal blood flow, to train an AI algorithm to generate flow maps from standard optical coherence tomography (OCT) images, exceeding the ability and bypassing the need for expert labeling. Deep learning was able to infer flow from single structural OCT images with similar fidelity to OCTA and significantly better than expert clinicians (P < 0.00001). Our model allows generating flow maps from large volumes of previously collected OCT data in existing clinical trials and clinical practice. This finding demonstrates a novel application of AI to medical imaging, whereby subtle regularities between different modalities are used to image the same body part and AI is used to generate detailed inferences of tissue function from structure imaging.