Vascular Attenuation Research Articles

Central Retinal Artery Occlusion Following Sphenopalatine Artery Embolization: A Case Report and Review of the Literature.

Report of a case of central retinal artery occlusion following sphenopalatine artery (SPA) embolization. A review of the literature describing complications following SPA embolization and ligation. Retrospective case report and literature review. A 68-year-old woman with a history notable for hypertension, hyperlipidemia, and eight years of intermittent right-sided epistaxis previously requiring blood transfusions underwent right-sided embolization of the SPA with the neurosurgery service. SPA embolization was achieved with Embosphere microspheres and Concerto coils. No thromboembolic complications were noted at the conclusion of the case. On waking from general anesthesia, the patient reported painless right sided vision loss and was found to have best-corrected visual acuity of light perception, a relative afferent pupillary defect, and a cherry-red spot with vascular attenuation consistent with central retinal artery occlusion (CRAO). CRAO can be a complication of ipsilateral SPA embolization.

Clinical audit of the image quality and customised contrast volume using P3T contrast injection software versus standard injection protocol in CT coronary angiography

IntroductionThe implications of shorter scan time and lower tube voltage in the dual-source CT coronary angiography (CTCA) scan protocol necessitate the adaptation of contrast media (CM) injection parameters. This audit evaluates the coronary arteries' vascular attenuation and image quality by comparing the personalised patient protocol technology (P3T) contrast injection software with standard injection protocol. The secondary aim is to determine the relationship between CM volume and the patient's weight. MethodologyA Siemens Somatom Definition Force CT Unit was used to scan 30 sets of patients between August 2020 and October 2020. Patients were selected retrospectively and separated into Standard Injection and P3T injection protocols. An experienced radiologist blinded to the groups reviewed the coronary vessels' contrast enhancement and image quality. ResultsOverall, the mean HU of all the main coronary artery vessels obtained from P3T injection software reached above 350 HU and was diagnostically sufficient. The mean attenuation at the proximal region of RCA in the 80–99 kg weight category was significantly higher in the P3T injection software than the standard injection protocol (p < 0.001). The CM volume proposed by P3T injection software for 40–59 kg was approximately 57 ± 5 mls, while 75 ml was used for the standard injection protocol. ConclusionP3T injection software in CTCA resulted in an adequate diagnostic attenuation of coronary arteries (>350HU) in all weight groups, most effectively in the higher weight group, while maintaining diagnostic image quality. Further, the P3T software reduces CM volumes in lower-weight patients. ImplicationsP3T software enables reducing CM volume in lower-weight patients while improving vascular enhancement in CTCA scans in higher-weight patients.

NoiseNet, a fully automatic noise assessment tool that can identify non-diagnostic CCTA examinations

Image noise and vascular attenuation are important factors affecting image quality and diagnostic accuracy of coronary computed tomography angiography (CCTA). The aim of this study was to develop an algorithm that automatically performs noise and attenuation measurements in CCTA and to evaluate the ability of the algorithm to identify non-diagnostic examinations. The algorithm, “NoiseNet”, was trained and tested on 244 CCTA studies from the Swedish CArdioPulmonary BioImage Study. The model is a 3D U-Net that automatically segments the aortic root and measures attenuation (Hounsfield Units, HU), noise (standard deviation of HU, HUsd) and signal-to-noise ratio (SNR, HU/HUsd) in the aortic lumen, close to the left coronary ostium. NoiseNet was then applied to 529 CCTA studies previously categorized into three subgroups: fully diagnostic, diagnostic with excluded parts and non-diagnostic. There was excellent correlation between NoiseNet and manual measurements of noise (r = 0.948; p < 0.001) and SNR (r = 0.948; <0.001). There was a significant difference in noise levels between the image quality subgroups: fully diagnostic 33.1 (29.8–37.9); diagnostic with excluded parts 36.1 (31.5–40.3) and non-diagnostic 42.1 (35.2–47.7; p < 0.001). Corresponding values for SNR were 16.1 (14.0–18.0); 14.0 (12.4–16.2) and 11.1 (9.6–14.0; p < 0.001). ROC analysis for prediction of a non-diagnostic study showed an AUC for noise of 0.73 (CI 0.64–0.83) and for SNR of 0.80 (CI 0.71–0.89). In conclusion, NoiseNet can perform noise and SNR measurements with high accuracy. Noise and SNR impact image quality and automatic measurements may be used to identify CCTA studies with low image quality.

Photon-Counting Detector CT Virtual Monoenergetic Images in Cervical Trauma Imaging-Optimization of Dental Metal Artifacts and Image Quality.

The aim of this study was to analyze the extent of dental metal artifacts in virtual monoenergetic (VME) images, as they often compromise image quality by obscuring soft tissue affecting vascular attenuation reducing sensitivity in the detection of dissections. Neck photon-counting CT datasets of 50 patients undergoing contrast-enhanced trauma CT were analyzed. Hyperattenuation and hypoattenuation artifacts, muscle with and without artifacts and vessels with and without artifacts were measured at energy levels from 40 keV to 190 keV. The corrected artifact burden, corrected image noise and artifact index were calculated. We also assessed subjective image quality on a Likert-scale. Our study showed a lower artifact burden and less noise in artifact-affected areas above the energy levels of 70 keV for hyperattenuation artifacts (conventional polychromatic CT images 1123 ± 625 HU vs. 70 keV VME 1089 ± 733 HU, p = 0.125) and above of 80 keV for hypoattenuation artifacts (conventional CT images -1166 ± 779 HU vs. 80 keV VME -1170 ± 851 HU, p = 0.927). Vascular structures were less hampered by metal artifacts than muscles (e.g., corrected artifact burden at 40 keV muscle 158 ± 125 HU vs. vessels -63 ± 158 HU p < 0.001), which was also reflected in the subjective image assessment, which showed better ratings at higher keV values and overall better ratings for vascular structures than for the overall artifact burden. Our research suggests 70 keV might be the best compromise for reducing metal artifacts affecting vascular structures and preventing vascular contrast if solely using VME reconstructions. VME imaging shows only significant effects on the general artifact burden. Vascular structures generally experience fewer metal artifacts than soft tissue due to their greater distance from the teeth, which are a common source of such artifacts.

Successful Treatment of Clinically Diagnosed Cancer-Associated Retinopathy with Intravitreal Dexamethasone Implant Followed by 0.18 mg Fluocinolone Implant without Systemic Immunosuppression.

To report a case of clinically diagnosed cancer-associated retinopathy (CAR) successfully treated with intravitreal corticosteroid implants without systemic immunosuppression. Case report with multimodal imaging. An 80-year-old man without known systemic malignancy presented with debilitating shimmering, hemeralopia and rapidly progressive bilateral vision loss following uncomplicated cataract surgery. Mild vitritis, extensive photoreceptor loss, mottling of retinal pigmentary epithelium (RPE), and mild vascular attenuation were found in both eyes. Full field electroretinogram (ffERG) showed severe bilateral rod-cone dysfunction. Infectious etiologies and vitreoretinal lymphoma were ruled out. During cancer workup, intravitreal corticosteroid treatment was offered. Significant anatomical improvement with reconstitution of ellipsoid zone, improved RPE irregularities and functional improvement, were observed 3 weeks after bilateral intravitreal dexamethasone implants (Ozurdex). 2 months later, patient received bilateral intravitreal 0.18mg fluocinolone acetonide implants (YUTIQ). Later, a colonic adenocarcinoma was found (pathologic stage pT3 pN0). Patient recovered well from surgery and no chemotherapy was needed. 9 months since bilateral intravitreal fluocinolone acetonide implants (11 months since bilateral intravitreal dexamethasone implants), best corrected vision maintained at 20/25-2 OD, 20/20 OS without ongoing treatments. Bilateral reconstitution of ellipsoid zones and nearly resolution of RPE irregularities remained stable. Repeat ffERG demonstrated improved cone response OS and stable diminished rod response OU. Patient reports resolution of ocular symptoms. The sustained improvements with intravitreal corticosteroid monotherapy suggest potential advantages using local therapy over systemic treatment. Long term follow-up is warranted. Further research is needed to evaluate the efficacy of using 0.18mg fluocinolone implant (YUTIQ) to treat CAR.

TOWARD AN IMAGING-CENTRIC DEFINITION OF NONPARANEOPLASTIC AUTOIMMUNE RETINOPATHY.

To explore characteristic imaging features of nonparaneoplastic autoimmune retinopathy (npAIR) to augment diagnostic criteria. This is a retrospective cohort study of patients with npAIR evaluated at the Emory Eye Center between 2013 and 2019. Multimodal fundus images were evaluated to characterize the evolution of the disease. Twenty-one eyes of 12 patients were classified as having npAIR. Five patients (42%) were female, with median (range) age of 59 years (45-85 years). Median baseline visual acuity was 20/30 (20/20 to hand motions). Disease was asymmetric in 11 patients (92%). Common imaging findings included absence of bone spicules (86% of affected eyes), presence of attenuated vessels (86%), and speckled hypoautofluorescence in perimacular and perivenular regions. Three eyes were noted to present early with subtle splotchy fundus autofluorescence abnormality, ultimately developing characteristic speckled perimacular hypoautofluorescence. On optical coherence tomography, 18 eyes (86%) had loss of outer retinal bands with relative foveal sparing and a tapered transition zone. Many eyes with npAIR exhibit a subacute, asymmetric, generalized photoreceptor degeneration featuring outer retinal atrophy with relative foveal sparing, retinal vascular attenuation, absence of bone spicules, and speckled hypoautofluorescence often in a perimacular and perivenular distribution. Findings of this study augment diagnostic criteria to improve specificity and accessibility of testing for npAIR.

Macular perfusion changes in people administered two types of COVID-19 vaccines: optical coherence tomography angiography study.

To evaluate macular chorioretinal flow changes on optical coherence tomography angiography, in participants who received inactivated and messenger RNA (mRNA) vaccines to prevent Coronavirus disease 2019 (COVID-19). In this prospective cohort study, healthy participants who received two doses of an inactivated COVID-19 vaccine (CoronaVac) and then one dose of an mRNA vaccine (BNT162b2) were examined before and after each vaccination. Ophthalmologic examination and imaging with optical coherence tomography angiography were performed during each visit. We evaluated vascular densities in the superficial and deep capillary plexuses in foveal, parafoveal, and perifoveal areas; the foveal avascular zone; and choriocapillaris flows (in 1- and 6-mm-diameter areas). One eye in each of the 24 participants was assessed. Superficial capillary plexus vascular densities in the parafoveal area were significantly lower after the second dose of the CoronaVac vaccine than after the first dose. In the deep capillary plexus, vascular attenuation was observed only in the parafoveal region after the first CoronaVac dose. However, in all regions, the deep capillary plexus vascular densities and subfoveal choriocapillaris flow were significantly decreased after the second CoronaVac dose. After the BNT162b2 dose, the superficial capillary plexus vascular densities, the deep capillary plexus vascular densities, and subfoveal choriocapillaris flow of most regions were significantly lower than those before vaccinations. Vascular attenuation, observed particularly after the second dose of the CoronaVac vaccine, may explain the pathogenesis of postvaccine ocular ischemic disorders reported in the literature. However, these disorders are extremely rare, and the incidence of thrombotic events caused by COVID-19 itself is higher.

Diagnostic Efficacy and Safety of Low-Contrast-Dose Dual-Energy CT in Patients With Renal Impairment Undergoing Transcatheter Aortic Valve Replacement.

This study aimed to evaluate the diagnostic efficacy and safety of low-contrast-dose, dual-source dual-energy CT before transcatheter aortic valve replacement (TAVR) in patients with compromised renal function. A total of 54 consecutive patients (female:male, 26:38; 81.9 ± 7.3 years) with reduced renal function underwent pre-TAVR dual-energy CT with a 30-mL contrast agent between June 2022 and March 2023. Monochromatic (40- and 50-keV) and conventional (120-kVp) images were reconstructed and analyzed. The subjective quality score, vascular attenuation, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were compared among the imaging techniques using the Friedman test and post-hoc analysis. Interobserver reliability for aortic annular measurement was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. The procedural outcomes and incidence of post-contrast acute kidney injury (AKI) were assessed. Monochromatic images achieved diagnostic quality in all patients. The 50-keV images achieved superior vascular attenuation and CNR (P < 0.001 in all) while maintaining a similar SNR compared to conventional CT. For aortic annular measurement, the 50-keV images showed higher interobserver reliability compared to conventional CT: ICC, 0.98 vs. 0.90 for area and 0.97 vs. 0.95 for perimeter; 95% limits of agreement width, 0.63 cm² vs. 0.92 cm² for area and 5.78 mm vs. 8.50 mm for perimeter. The size of the implanted device matched CT-measured values in all patients, achieving a procedural success rate of 92.6%. No patient experienced a serum creatinine increase of ≥ 1.5 times baseline in the 48-72 hours following CT. However, one patient had a procedural delay due to gradual renal function deterioration. Low-contrast-dose imaging with 50-keV reconstruction enables precise pre-TAVR evaluation with improved image quality and minimal risk of post-contrast AKI. This approach may be an effective and safe option for pre-TAVR evaluation in patients with compromised renal function.

Офтальмоскопия как метод оценки фармакологической безопасности препаратов

The toxic effects of drugs can affect the anterior segment of the eye, the lens and the poste­rior segment of the eye. Оphthalmoscopy is used аor intravital assessment of the condition of the posterior segment of the eye. Сharacteristic changes, that can be observed by ophthalmoscopy, appear most often after systemic or intraocular use of drugs. However, before interpreting pathological ophthalmoscopic signs in laboratory animals, normal variations in the fundus pattern should be known, since among animal species there is a significant diversity in the structure of the fundus (presence or absence of tapetum, pigmentation, and type of nutrition of the retina). Pathological data obtained during ophthalmoscopy, indicating the toxic effect of the drug, can be expressed in the form of exudative, inflammatory, degenerative and atrophic processes, expansion and tortuosity of the retinal vessels, discoloration of the tapetum, retinal detachment, hemorrhages in the fundus, vascular attenuation of the retina and hyperreflectivity tapetum. Ophthalmoscopic examination is the most important tool for diagnosing pathologies of the posterior segment of the eyes in laboratory animals participating in the study of the pharmacological safety of drugs. Ophthalmoscopy should be carried out by a highly qualified veterinary ophthalmologist at all stages of the preclinical study of the drug.

Low Dose Iodinated Contrast Material and Radiation for Virtual Monochromatic Imaging in Craniocervical Dual-Layer Spectral Detector Computed Tomography Angiography: A Prospective and Randomized Study

Rationale and ObjectivesTo investigate the feasibility of virtual monochromatic imaging (VMI) of dual-layer spectral detector computed tomography (SDCT) to reduce iodinated contrast material and radiation dose in craniocervical computed tomography angiography (CTA). Materials and MethodsA total of 280 consecutively selected patients performed craniocervical CTA with SDCT were prospectively selected and randomly divided into four groups (A, DoseRight index (DRI) 31, iopromide 370mgI/ml, volume 0.8ml/kg; B, DRI 26, iopromide 370mgI/ml, volume 0.4ml/kg; C, DRI 26, ioversol 320mgI/ml, volume 0.4ml/kg; D, DRI 26, iohexol 300mgI/ml, volume 0.4ml/kg). 50-70 kiloelectron volts (keV) VMIs in group B were reconstructed and compared with group A to select the optimal keV. Then, the optimal keV in groups B, C and D was reconstructed and compared. Objective image quality, including vascular attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), was evaluated. Subjective image quality was assessed using a 5-point Likert scale. In addition, the effective dose (ED), iodine load and iodine delivery rate (IDR) were compared between groups A and D. Results55 keV VMI was the optimal VMI in group B. The objective and subjective image quality of 55 keV VMI in group B were equal to or better than those of the CI in group A. The SNR, CNR and subjective image quality in group D were similar to those in group B (P>0.05). The ED, iodine load and IDR of group D were reduced by 44%, 59%, and 19%, respectively, when compared with those of group A. ConclusionsLow dose iodinated contrast material and radiation for 55 keV VMI in craniocervical CTA using SDCT could still provide equivalent or better image quality than the conventional scanning protocol.

Optimal combination periprosthetic vasculature visualization and metal artifact reduction by spectral computed tomography using virtual monoenergetic images in total hip arthroplasty

ObjectivesTo investigate the optimal parameters of spectral CT for preferably visualizing the periprosthetic vasculature and metal artifact reduction (MAR) in total hip arthroplasty (THA).MethodsA total of 34 THA of 30 patients were retrospectively included. Image reconstructions included conventional image (CI), CI combined with MAR (CIMAR), and virtual monoenergetic images (VMI) combined with MAR (VMIMAR) at 50–120 keV. The attenuation and standard deviation of the vessel and artifact, and the width of artifact were measured. Qualitative scoring was evaluated including the vascular contour, the extent of artifact, and overall diagnostic evaluation.ResultsThe attenuation, noise of the vessel and artifact, and the width of artifact decreased as the energy level increased (p < 0.001). The downtrend was relatively flat at 80–120 keV, and the vascular attenuation dropped to 200 HU at 90 keV. The qualitative rating of vascular contour was significantly higher at CIMAR (3.47) and VMIMAR 60–80 keV (2.82–3.65) compared with CI (2.03) (p ≤ 0.029), and the highest score occurred at 70 and 80 keV (3.65 and 3.56). The score of the extent of artifact was higher at VMIMAR 80 keV than CIMAR (3.53 VS 3.12, p = 0.003). The score of the overall diagnostic evaluation was higher at VMIMAR 70 and 80 keV (3.32 and 3.53, respectively) than CIMAR (3.12) (p ≤ 0.035).ConclusionEighty kiloelectron volts on VMIMAR, providing satisfactorily reduced metal artifacts and improved vascular visualization, can be an optimal recommended parameter of spectrum CT for the assessment of periprosthetic vasculature in THA patients.Critical relevance statementThe metal artifact is gradually reducing with increasing energy level; however, the vascular visualization is worsening. The vascular visualization is terrible above 100 keV, while the vessel is disturbed by artifacts below 70 keV. The best performance is found at 80 keV.Key points• VMIMAR can provide both reduced metal artifacts and improved vascular visualization.• Eighty kiloelectron volts on VMIMAR performs best in vascular visualization of total hip arthroplasty patients.• Energy spectrum CT is recommended for routine use in patients with total hip arthroplasty.Graphical

Preventive Effects of Exosome-Rich Conditioned Medium From Amniotic Membrane-Derived Mesenchymal Stem Cells for Diabetic Retinopathy in Rats.

Diabetic retinopathy (DR) is an important disease that causes vision loss in many diabetic patients. Stem cell therapy has been attempted for treatment of this disease; however, it has some limitations. This study aimed to evaluate the preventive efficacy of exosome-rich conditioned medium (ERCM) derived from amniotic membrane stem cells for DR in rats. Twenty-eight 8-week-old male Sprague-Dawley rats were divided into three groups: group 1, normal control (Con) group; group 2, diabetes mellitus (DM) group; and group 3, DM with ERCM-treated (DM-ERCM) group. DM was induced by intraperitoneal injection of streptozotocin. The DM-ERCM group received ERCM containing 1.2 × 10⁹ exosomes into subconjunctival a total of four times every 2 weeks. On electroretinogram, the DM-ERCM group had significantly higher b-wave and flicker amplitudes than those in the DM group. In fundoscopy, retinal vascular attenuation was found in both the DM and DM-ERCM groups; however, was more severe in the DM group. On histology, the ganglion cell and nerve fiber layer rates of the total retinal layer significantly increased in the DM group compared with the Con group, whereas the DM-ERCM group showed no significant difference compared with the Con group. Cataracts progressed significantly more in the DM group than that in the DM-ERCM group and there was no uveitis in the DM-ERCM group. Subconjunctival ERCM delayed the progression of DR and cataracts and significantly reduced the incidence of uveitis. Our study shows the clinical potential of minimally invasive exosome-rich conditioned medium treatment to prevent diabetic retinopathy.

The impact of body compositions on contrast medium enhancement in chest CT: a randomised controlled trial.

To compare a fixed-volume contrast medium (CM) protocol with a combined total body weight (TBW) and body composition-tailored protocol in chest CT. Patients referred for routine contrast enhanced chest CT were prospectively categorised as normal, muscular or overweight. Patients were accordingly randomised into two groups; Group 1 received a fixed CM protocol. Group 2 received CM volume according to a body composition-tailored protocol. Objective image quality comparisons between protocols and body compositions were performed. Differences between groups and correlation were analysed using t-test and Pearson's r. A total of 179 patients were included: 87 in Group 1 (mean age, 51 ± 17 years); and 92 in Group 2 (mean age, 52 ± 17 years). Compared to Group 2, Group 1 showed lower vascular attenuation in muscular (mean 346 Hounsfield unit (HU) vs 396 HU; p = 0.004) and overweight categories (mean 342 HU vs 367 HU; p = 0.12), while normal category patients showed increased attenuation (385 vs 367; p = 0.61). In Group 1, strongest correlation was found between attenuation and TBW in muscular (r = -.49, p = 0.009) and waist circumference in overweight patients (r = -.50, p = 0.005). In Group 2, no significant correlations were found for the same body size parameters. In Group 1, 13% of the overweight patients was below 250 HU (p = 0.053). A combined TBW and body composition-tailored CM protocol in chest CT resulted in more homogenous enhancement and fewer outliers compared to a fixed-volume protocol. This is, to our knowledge, the first study to investigate the impact of various body compositions on contrast medium enhancement in chest CT.

Saving Contrast Media in Coronary CT Angiography with Photon-Counting Detector CT

To determine the optimal virtual monoenergetic image (VMI) energy level and the potential of contrast-media (CM) reduction for coronary computed tomography angiography (CCTA) with photon-counting detector CT (PCD-CT). In this institutional review board-approved study, patients who underwent CCTA with dual-source PCD-CT with an identical scan protocol and radiation dose were included. In group 1, CCTA was performed with our standard CM protocol (volume: 72-85.2mL, 370mg iodine/mL). VMIs were reconstructed from 40 to 60keV at 5keV increments. Objective image quality (IQ) (vascular attenuation, image noise, and contrast-to-noise ratio [CNR]) was measured. Two blinded, independent readers rated subjective IQ (overall IQ, subjective image contrast, and subjective noise using a five-point discrete visual scale). Results of group 1 served to determine the best VMI level for CCTA. In group 2, CM volume was reduced by 20%, and in group 3 by another 20%. A total of 100 patients were enrolled (45 females, mean age 54±13 years). Inter-reader agreement was good-to-excellent for all comparisons (κ > 0.6). In group 1, the best VMI level regarding objective and subjective IQ was 45keV, which was selected as the reference for groups 2 and 3. For group 2, mean vascular attenuation was 890 Hounsfield units (HU) and mean CNR was 26, with no differences compared to group 1, 45keV for both objective and subjective IQ. For group 3, mean vascular attenuation was 676 HU and mean CNR was 21, and all patients were rated as diagnostic except one (severe motion artifacts). Increased IQ of PCD-CT can be used for considerable CM volume reduction while still maintaining a diagnostic IQ of CCTA.

Virtual Monoenergetic Imaging of Lower Extremities Using Dual-Energy CT Angiography in Patients with Diabetes Mellitus.

Type 2 diabetes mellitus (DM) is the most common metabolic disorder in the world and an important risk factor for peripheral arterial disease (PAD). CT angiography represents the method of choice for the diagnosis, pre-operative planning, and follow-up of vascular disease. Low-energy dual-energy CT (DECT) virtual mono-energetic imaging (VMI) has been shown to improve image contrast, iodine signal, and may also lead to a reduction in contrast medium dose. In recent years, VMI has been improved with the use of a new algorithm called VMI+, able to obtain the best image contrast with the least possible image noise in low-keV reconstructions. To evaluate the impact of VMI+ DECT reconstructions on quantitative and qualitative image quality in the evaluation of the lower extremity runoff. We evaluated DECT angiography of lower extremities in patients suffering from diabetes who had undergone clinically indicated DECT examinations between January 2018 and January 2023. Images were reconstructed with standard linear blending (F_0.5) and low VMI+ series were generated from 40 to 100 keV, in an interval of 15 keV. Vascular attenuation, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated for objective analysis. Subjective analysis was performed using five-point scales to evaluate image quality, image noise, and diagnostic assessability of vessel contrast. Our final study cohort consisted of 77 patients (41 males). Attenuation values, CNR, and SNR were higher in 40-keV VMI+ reconstructions compared to the remaining VMI+ and standard F_0.5 series (HU: 1180.41 ± 45.09; SNR: 29.91 ± 0.99; CNR: 28.60 ± 1.03 vs. HU 251.32 ± 7.13; SNR: 13.22 ± 0.44; CNR: 10.57 ± 0.39 in standard F_0.5 series) (p < 0.0001). Subjective image rating was significantly higher in 55-keV VMI+ images compared to the other VMI+ and standard F_0.5 series in terms of image quality (mean score: 4.77), image noise (mean score: 4.39), and assessability of vessel contrast (mean value: 4.57) (p < 0.001). DECT 40-keV and 55-keV VMI+ showed the highest objective and subjective parameters of image quality, respectively. These specific energy levels for VMI+ reconstructions could be recommended in clinical practice, providing high-quality images with greater diagnostic suitability for the evaluation of lower extremity runoff, and potentially needing a lower amount of contrast medium, which is particularly advantageous for diabetic patients.

Feasibility of Ultra-Low Volume Contrast-Saline Mixture Injection With Dual-Flow Technique in a Pre-TAVI Computed Tomography Angiography.

To explore the feasibility and image quality of ultra-low volume contrast-saline mixture injection with dual-flow injection technique in a computed tomography angiography (CTA) protocol in patients scheduled for transcatheter aortic valve implantation (TAVI). Forty (40) TAVI candidates underwent investigation with CTA using a third-generation dual-source CT scanner between September and November 2020. Different volumes of a monophasic contrast-saline mixture at an 80:20 ratio were administered at an infusion rate of 3 mL/s in 20 patients (group A). The injected volume was based on patient body mass index (BMI): 50 mL if BMI <29 kg/m2 and 63 mL if BMI >29 kg/m2. The other 20 patients (group B)-the control cases-received a total of 65 mL of contrast medium (CM), in multiphasic injections at different flow rates, followed by 10 mL of saline. The images that were obtained were prospectively evaluated for image quality, vessel attenuation (HU), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and estimated radiation dose. Image quality of the aortic root and ilio-femoral vessels was diagnostic in all patients. Vascular attenuation was >200 HU and CNR >3 at any vessel level. Data from this study suggest that a monophasic ultra-low volume contrast-saline mixture injection with a dual-flow technique can provide clear visualisation of the aortic root and ilio-femoral vessels in pre-TAVI CTA, which is comparable with a standard multiphasic volume injection protocol.

Preliminary characterization of a novel form of progressive retinal atrophy in the German Spitz dog associated with a frameshift mutation in GUCY2D.

To describe the clinical, preliminary electroretinographic and optical coherence tomography features of a newly identified form of progressive retinal atrophy (PRA) in German Spitzes, and identify the causal gene mutation. Thirty-three client-owned German Spitz dogs were included. All animals underwent a full ophthalmic examination, including vision testing. In addition, fundus photography, ERG, and OCT were performed. A DNA-marker-based association analysis was performed to screen potential candidate genes and the whole genomes of four animals were sequenced. Initial fundus changes were pale papilla and mild vascular attenuation. Oscillatory nystagmus was noted in 14 of 16 clinically affected puppies. Vision was impaired under both scotopic and photopic conditions. Rod-mediated ERGs were unrecordable in all affected dogs tested, reduced cone-mediated responses were present in one animal at 3months of age and unrecordable in the other affected animals tested. Multiple small retinal bullae were observed in three clinically affected animals (two with confirmed genetic diagnosis). OCT showed that despite loss of function, retinal structure was initially well-preserved, although a slight retinal thinning developed in older animals with the ventral retina being more severely affected. Pedigree analysis supported an autosomal recessive inheritance. A mutation was identified in GUCY2D, which segregated with the disease (NM_001003207.1:c.1598_1599insT; p.(Ser534GlufsTer20)). Human subjects with GUCY2D mutations typically show an initial disconnect between loss of function and loss of structure, a feature recapitulated in the affected dogs in this study. We identified early-onset PRA in the German Spitz associated with a frameshift mutation in GUCY2D.

Deep learning image reconstruction algorithm: impact on image quality in coronary computed tomography angiography

PurposeTo perform a comprehensive intraindividual objective and subjective image quality evaluation of coronary CT angiography (CCTA) reconstructed with deep learning image reconstruction (DLIR) and to assess correlation with routinely applied hybrid iterative reconstruction algorithm (ASiR-V).Material and methodsFifty-one patients (29 males) undergoing clinically indicated CCTA from April to December 2021 were prospectively enrolled. Fourteen datasets were reconstructed for each patient: three DLIR strength levels (DLIR_L, DLIR_M, and DLIR_H), ASiR-V from 10% to 100% in 10%-increment, and filtered back-projection (FBP). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) determined objective image quality. Subjective image quality was assessed with a 4-point Likert scale. Concordance between reconstruction algorithms was assessed by Pearson correlation coefficient.ResultsDLIR algorithm did not impact vascular attenuation (P ≥ 0.374). DLIR_H showed the lowest noise, comparable with ASiR-V 100% (P = 1) and significantly lower than other reconstructions (P ≤ 0.021).DLIR_H achieved the highest objective quality, with SNR and CNR comparable to ASiR-V 100% (P = 0.139 and 0.075, respectively). DLIR_M obtained comparable objective image quality with ASiR-V 80% and 90% (P ≥ 0.281), while achieved the highest subjective image quality (4, IQR: 4–4; P ≤ 0.001). DLIR and ASiR-V datasets returned a very strong correlation in the assessment of CAD (r = 0.874, P = 0.001).ConclusionDLIR_M significantly improves CCTA image quality and has very strong correlation with routinely applied ASiR-V 50% dataset in the diagnosis of CAD.

Inner Retinal Thickness and Vasculature in Patients with Reticular Pseudodrusen

Introduction: The aim of this study was to investigate retinal layer thickness and vessel density differences between patients with reticular pseudodrusen (RPD) and intermediate dry age-related macular degeneration (iAMD). Methods: Participants included in the study were patients diagnosed by retinal specialists with RPD, iAMD, and both RPD and iAMD at our academic referral center, seen from May 2021 until February 2022. The central 3 mm retinal thickness was measured using spectral-domain optical coherence tomography (Heidelberg Spectralis HRA+OCT System; Heidelberg Engineering, Heidelberg, Germany). Individual retinal thickness measurements were obtained from the innermost layer (nerve fiber layer) until the outermost layer (retinal pigment epithelium [RPE]). Each thickness measurement was subdivided into nine Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. For the vessel density, OCT angiography from the Heidelberg Spectralis System was measured using proprietary third-party software (AngioTool; National Institutes of Health, National Cancer Institute, Bethesda, MD). Clinical and demographic characteristics were compared across the three groups (iAMD, RPD, iAMD and RPD) and analyzed with necessary adjustments. Linear mixed-effects models with necessary corrections were employed to compare continuous eye-level measurements between our three groups as well as in pairwise fashion using the R statistical programming software (R version 4.2.1). Results: A total of 25 eyes of 17 patients with RPD, 20 eyes of 15 patients with iAMD, and 14 eyes of 9 patients with both iAMD and RPD were analyzed. Retinal thickness analysis identified that the superior inner (p = 0.028) and superior outer (p = 0.027) maculas of eyes with both iAMD and RPD were significantly thinner than those with iAMD alone. In eyes with RPD, the superior inner and superior outer RPE (p = 0.011 and p = 0.05, respectively), outer plexiform layer (p = 0.003 and p = 0.013, respectively), and inner nuclear layer (p = 0.034 and p = 0, respectively) were noted to be thinner compared to eyes with iAMD alone. In addition, the macular deep capillary plexus vessel density was significantly reduced in eyes with RPD compared to eyes with iAMD (p = 0.017). Conclusion: Patients with RPD had inner retinal structural as well as vascular changes compared to iAMD patients. Inner retinal vascular attenuation should be investigated further to see if there is a causal association with retinal thinning.

Superficial and Deep Capillary Plexus Nonperfusion in Nonaccidental Injury on OCTA.

A 5-year-old Caucasian male with a history nonaccidental injury (NAI) at age 1 presented with new onset no light perception in the left eye due to a closed funnel retinal detachment. The right eye showed optic nerve pallor, peripheral vascular attenuation, and leakage. Optical coherence tomography angiography (OCTA) revealed significant parafoveal attenuation of the superficial vascular plexus, intermediate capillary plexus, and the deep capillary plexus. This correlated with inner and middle retinal layer thinning temporal to the fovea and preservation of the ellipsoid zone. The peripapillary vascular plexus was preserved. Laser photocoagulation was performed to the nonperfused peripheral retina and intravitreal bevacizumab was injected. OCTA may be used in patients with NAI to characterize macular ischemia changes. Attenuation of the superficial, intermediate, and deep capillary plexuses in our patient may represent chronic ischemic retinal changes that arise from traumatic injury to the vitreoretinal interface and inner retina in NAI.