Impact of the COVID-19 Pandemic on Refractive Surgery.

PURPOSE OF REVIEW: In this article, we review the impact of the COVID-19 pandemic on refractive surgery. RECENT FINDINGS: COVID-19 infection frequently causes eye symptoms, most commonly conjunctivitis or mild irritation. While virus can be detected in tears of symptomatic patients, the risk of transmission via this route appears low. SUMMARY: Refractive surgery consultations were significantly reduced during the pandemic; however, volume is rebounding quickly likely due to a number of lifestyle, health, and financial factors. Laser refractive and intraocular surgery likely confer a low risk of virus spread, especially in asymptomatic patients. Screening prior to the refractive consultation and surface disinfection in the clinic and operating room can help reduce transmission risk further.

Unplanned returns to the operating room within three months of pediatric cataract-related intraocular surgery: indications and risk factors.

PURPOSE: To evaluate the indications and associated risk factors for unplanned returns to the operating room within 90 days of pediatric cataract-related surgery. METHODS: The medical records patients undergoing either cataract extraction or secondary intraocular lens (IOL) implantation at a single center from 1991 to 2018 were reviewed retrospectively. RESULTS: A total of 1,392 eyes of 989 patients were included, with 48 unplanned reoperations in 46 eyes of 43 patients, yielding a reoperation rate of 3.3% (46/1392) for one reoperation and 0.14% (2/1392) for two within 90 days of surgery. Of the 48 reoperations, indications for reoperation were as follows: lens cortex reproliferation (n = 14), elevated intraocular pressure (n = 11), inflammatory pupillary membranes (n = 7), vitreous wick to the cataract surgery wound (n = 6), synechiae (n = 3), uveitis (n = 3), posterior capsule opacification in an eye with intact posterior capsule (n = 1), retained cortex (n = 1), traumatic iris prolapse (n = 1), and foreign body in anterior chamber (n = 1). Risk factors for an unplanned reoperation included a history of traumatic cataract (relative risk, 2.55) or age <1 year at time of first surgery (relative risk, 3.02). In the absence of these risk factors, the reoperation rate was 1.1%. CONCLUSIONS: Unplanned reoperations after pediatric cataract surgery are uncommon, but when they occur it is often in the setting of trauma or surgery performed before the age of 1 year.

Advanced Robotic Angiography Systems for Image Guidance During Conventional Transarterial Chemoembolization: Impact on Radiation Dose and Image Quality.

OBJECTIVES: The aim of this study was to compare 2 advanced robotic angiography systems for real-time image guidance in terms of radiation dose and image quality (IQ) during conventional transarterial chemoembolization (C-TACE) of hepatic malignant tumors. MATERIALS AND METHODS: One hundred six patients (57 women/49 men; mean age, 60 ± 11 years) who had undergone C-TACE using 2 generations of robotic angiography platforms for image guidance were included in this retrospective study. Patients were divided into 2 groups (n = 53, respectively): group 1 (first generation) and group 2 (second generation). Radiation dose for fluoroscopy and digital subtraction angiography (DSA) was compared between first-generation and second-generation angiography equipment, respectively. Among several features of the second-generation compared with the first-generation system, improvements included a refined crystalline detector system for enhanced noise reduction and advanced CARE filter software for lowering radiation dose. Radiation dose was measured using an ionization chamber. Image quality was assessed by 3 radiologists using 5-point Likert scales. RESULTS: Both groups were comparable in terms of number and location of lesions, as well as body weight, body mass index, and anatomical variants of feeding hepatic arteries (all P > 0.05). Dose-area product (DAP) for fluoroscopy was significantly lower in group 2 (1.4 ± 1.1 Gy·cm) compared with group 1 (2.8 ± 3.4 Gy·cm; P = 0.001). For DSA, DAP was significantly lower (P = 0.003) in group 2 (2.2 ± 1.2 Gy·cm) versus group 1 (4.7 ± 2.3 Gy·cm). Scores for DSA IQ indicated significant improvements for group 2 by 30% compared with group 1 (P = 0.004). Regarding fluoroscopy, scores for IQ were 76% higher in group 2 compared with group 1 (P = 0.001). Good to excellent interrater agreement with Fleiss kappa coefficients of κ = 0.75 for group 1 and κ = 0.74 for group 2 were achieved. CONCLUSIONS: Most recent generation robotic angiography equipment allows for considerable radiation dose reductions while improving IQ in fluoroscopy and DSA image guidance during C-TACE treatment.

Beam-hardening in 70-kV Coronary CT angiography: Artifact reduction using an advanced post-processing algorithm.

PURPOSE: To investigate the effect of an iterative beam-hardening correction algorithm (iBHC) on artifact reduction and image quality in coronary CT angiography (cCTA) with low tube voltage. MATERIAL AND METHODS: Thirty-six patients (17 male, mean age, 57.3 ±â€¯14.5 years) were prospectively enrolled in this IRB-approved study and underwent 70-kV cCTA using a third-generation dual-source CT scanner. Images were reconstructed using a standard algorithm (Bv36) both with and without the iBHC technique. Several region-of-interest (ROI) measurements were performed in the inferior wall of the left ventricle (LV), an area prone to beam-hardening, as well as other myocardial regions. Coronary contrast-to-noise (CNR) and signal-to-noise ratios (SNR) were calculated. Two radiologists assessed subjective image quality. RESULTS: The iBHC algorithm generally increased myocardial attenuation in all ROIs (P < 0.566); however, the increase was significantly more distinct in beam-hardening prone areas such as the inferior LV (increase, +13.9 HU, +18.6%, P < 0.001), compared to the remaining myocardium (increase, +4.4 HU, +4.5%, P < 0.003). While no significant difference was found for image noise (P < 0.092), greater CNR and SNR values for the left main coronary artery (increase, +20.7% and +17.3%, respectively) were found using the iBHC algorithm (both with P < 0.001). Subjective image quality was comparable between both image series (P = 0.217). CONCLUSION: The iBHC post-processing algorithm leads to significantly reduced beam-hardening while providing improved objective and equivalent subjective image quality in 70-kV cCTA.

Assessment of salivary gland tumors using MRI and CT: impact of experience on diagnostic accuracy.

RATIONALE AND OBJECTIVES: To analyze the accuracy of radiological diagnosis in MRI and CT studies of salivary gland tumors depending on the radiologist's experience. MATERIALS AND METHODS: Three radiologists with differing experience (R1 > 20, R2 > 11, and R3 > 7 years, respectively) retrospectively reviewed 128 cases (116 MRI, 12 CT studies) with suspected salivary gland tumors regarding dignity and classification using histopathology as a reference standard. Sensitivity, specificity, positive/negative predictive value and inter-observer agreement (using Cohen's κ) were calculated to compare diagnostic performance. RESULTS: Lesions were benign in 87 and in 23 cases malignant. Neoplasia was absent in 18 cases (15 cases without neoplasia and 3 cases without disease). The highest inter-observer agreement for determining dignity using CT was found between R1 and R2 (κ = 0.74, p < 0.001), and the lowest between R2 and R3 (κ = 0.28, p < 0.001). MRI sensitivity/specificity for classifying pleomorphic adenomas was as follows: R1 (100%/100%), R2 (76.92%/87.01%), R3 (43.53%/67.53%), and for CT: R1 (100%/100%), R2 (100%/88.89%), R3 (66.67%/88.89%; for Warthin's tumor using MRI: R1 (100%/97.44%), R2 (68.42%/83.33%), R3 (50.00%/67.95%), and using CT: R1 (100%/100%), R2 (50.00%/100%), R3 (100%/100%; for squamous cell carcinomas using MRI: R1 (100%/100%), R2 (75.00%/97.12%), R3 (75.00%/99.04%), and using CT: R1 (100%/100%), R2 (66.67%/88.89%), R3 (66.67%/66.67%). The highest agreement was found between R1 and R2 for MRI (κ = 0.62, p < 0.001), and the lowest between R1 and R3 at MRI (κ = 0.28, p < 0.001). CONCLUSION: Diagnostic accuracy in the assessment of salivary gland tumors strongly depends on the observer's expertise and increases with higher experience.

Predicting Treatment Response of Colorectal Cancer Liver Metastases to Conventional Lipiodol-Based Transarterial Chemoembolization Using Diffusion-Weighted MR Imaging: Value of Pretreatment Apparent Diffusion Coefficients (ADC) and ADC Changes Under Therapy.

PURPOSE: To use absolute pretreatment apparent diffusion coefficients (ADC) derived from diffusion-weighted MR imaging (DWI) to predict response to repetitive cTACE for unresectable liver metastases of colorectal carcinoma (CRLM) at 1 and 3 months after start of treatment. MATERIALS AND METHODS: Fifty-five metastases in 34 patients were examined with DWI prior to treatment and 1 month after initial cTACE. Treatment was performed in 4-week intervals. Response was evaluated at 1 and 3 months after start of therapy. Metastases showing a decrease of ≥30% in axial diameter were classified as responding lesions. RESULTS: One month after initial cTACE, seven lesions showed early response. There was no significant difference in absolute pretreatment ADC values between responding and non-responding lesions (p = 0.94). Three months after initial cTACE, 17 metastases showed response. There was a significant difference (p = 0.021) between absolute pretreatment ADC values of lesions showing response (median 1.08 × 10-3 mm2/s) and no response (median 1.30 × 10-3 mm2/s). Pretreatment ADC showed fair diagnostic value to predict response (AUC 0.7). Lesions showing response at 3 months also revealed a significant increase in ADC between measurements before treatment and at one month after initial cTACE (p < 0.001). Applying an increase in ADC of 12.17%, response at 3 months after initial cTACE could be predicted with a sensitivity and specificity of 77 and 74%, respectively (AUC 0.817). Furthermore, there was a strong and significant correlation (r = 0.651, p < 0.001) between percentage change in size after third cTACE and percentage change in ADC. CONCLUSION: In patients with CRLM, ADC measurements are potential biomarkers for assessing response to cTACE.

State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism.

OBJECTIVE: Pulmonary CT angiography (CTA) is the imaging modality of choice in suspected acute pulmonary embolism (PE). Current pulmonary CTA techniques involve ever lower doses of contrast medium and radiation along with advanced postprocessing applications to enhance image quality, diagnostic accuracy, and provide added value in patient management. The objective of this article is to summarize these current developments and discuss the appropriate use of state-of-the-art pulmonary CTA. CONCLUSION: Pulmonary CTA is well established as a fast and reliable means of excluding or diagnosing PE. Continued developments in CT system hardware and postprocessing techniques will allow incremental reductions in radiation and contrast material requirements while improving image quality. Advances in risk stratification and prognostication from pulmonary CTA examinations should further refine its clinical value while minimizing the potential harm from overutilization and overdiagnosis.

Radiation Optimized Dual-source Dual-energy Computed Tomography Pulmonary Angiography: Intra-individual and Inter-individual Comparison.

OBJECTIVES: This study aimed to intra-individually and inter-individually compare image quality, radiation dose, and diagnostic accuracy of dual-source dual-energy computed tomography pulmonary angiography (CTPA) protocols in patients with suspected pulmonary embolism (PE). METHODS: Thirty-three patients with suspected PE underwent initial and follow-up dual-energy CTPA at 80/Sn140 kVp (group A) or 100/Sn140 kVp (group B), which were assigned based on tube voltages. Subjective and objective CTPA image quality and lung perfusion map image quality were evaluated. Diagnostic accuracies of CTPA and perfusion maps were assessed by two radiologists independently. Effective dose (ED) was calculated and compared. RESULTS: Mean computed tomography (CT) values of pulmonary arteries were higher in group A than group B (P = .006). There was no difference in signal-to-noise ratio and contrast-to-noise ratio between the two groups (both P > .05). Interobserver agreement for evaluating subjective image quality of CTPA and color-coded perfusion images was either good (κ = 0.784) or excellent (κ = 0.887). Perfusion defect scores and diagnostic accuracy of CTPA showed no difference between both groups (both P > .05). Effective dose of group A was reduced by 45.8% compared to group B (P < .001). CONCLUSIONS: Second-generation dual-source dual-energy CTPA with 80/Sn140 kVp allows for sufficient image quality and diagnostic accuracy for detecting PE while substantially reducing radiation dose.