A streamlined workflow for comprehensive 4DCT imaging QA with automated analysis of spatial integrity and image quality.

In order to analyze the impact of multisource vibration on the imaging quality of aerospace optical payload during camera scanning, a dynamic imaging quality degradation model fused with satellite vibration filter templates is established. Firstly, according to the motion scanning process of the TDI camera, a filter template combining the amplitude and frequency of the vibration source is designed; Secondly, a piecewise function of satellite vibration with a frequency range of 1 Hz to 1000 Hz is obtained by curve fitting, and the amplitudes of different frequency ranges are brought into the image filter template to simulate the output image affected by the vibration. Finally, the output degraded image is analyzed through structural similarity and mean square error. The simulation results show that during the imaging process of the aerospace scanning mirror, the line frequency of the camera changes regularly with the scanning speed. When platform vibration frequency is similar to the camera’s exposure frequency, it will have a large impact on image quality. Therefore, when the camera’s exposure frequency is 110 Hz, vibration at a frequency of 110 Hz will further degrade the image quality. This article is expected to provide guidance for spatial vibration suppression and image quality degradation assessment in the imaging process of aerospace scanning mirrors.

We are developing a method to objectively quantify image quality and applying it to the optimization of fast magnetic resonance imaging methods. In MRI, to capture the details of a dynamic process, it is critical to have both high temporal and spatial resolution. However, there is typically a trade-off between the two, making the sequence engineer choose to optimize imaging speed or spatial resolution. In response to this problem, a number of different fast MRI techniques have been proposed. To evaluate different fast MRI techniques quantitatively, we use a perceptual difference model (PDM) that incorporates various components of the human visual system. The PDM was validated using subjective image quality ratings by naive observers and task-based measures as defined by radiologists. Using the PDM, we investigated the effects of various imaging parameters on image quality and quantified the degradation due to novel imaging techniques including keyhole, keyhole Dixon fat suppression, and spiral imaging. Results have provided significant information about imaging time versus quality tradeoffs aiding the MR sequence engineer. The PDM has been shown to be an objective tool for measuring image quality and can be used to determine the optimal methodology for various imaging applications.

Dose reduction techniques for computed tomography angiography (CTA) in children with cardiovascular diseases have the potential of reducing risks of radiation-induced cancer. To evaluate effectiveness of these techniques, both radiation dose and image quality must be compared. While clinically practical methods of estimating effective dose are available, there are no generally accepted metrics for the assessment of image quality in CTA. We introduce a measurable and reproducible image quality index, CTA QI. Using this index, along with calculated effective dose, we test the hypothesis that volume scan CTA delivers comparable image quality at substantially reduced radiation dose when compared to helical CTA. CTA QI is a measure of intraluminal contrast variation in three-dimensions, and it is calculated from standardized measurements of means and standard deviations of Hounsfield units in the thoracic descending aorta. From institutional database, 83 studies of CTA for thoracic cardiovascular diseases were retrospectively identified. CTA QI values were independently measured by two radiologists and compared using correlation. CTA QI and DLP-derived effective dose were compared for the following groups: non-cardiac gated wide-detector and helical CTA, ECG-synchronized retrospective wide-detector and helical CTA, ECG-synchronized wide detector retrospective and target technique CTA. Statistical significance was evaluated with the Student-t test. The correlations of CTA QI values between the radiologists were 0.83 and 0.92 for non-gated studies and ECG-synchronized studies respectively. Comparing non-gated volume scan CTA to helical CTA, there was a radiation dose reduction of 69% (P < 0.0001) without a significant change in CTA QI (1.4 ± 1.0 vs. 1.9 ± 1.4, P = 0.13). Comparing retrospective ECG-synchronized wide-detector CTA to helical CTA, there was a radiation dose reduction of 46% (P < 0.0001) with and improvement in CTA QI (1.0 ± 0.8 vs. 3.7 ± 3.4, P < 0.01). Comparing ECG-synchronized wide-detector target CTA to retrospective CTA, there was a radiation dose reduction of 68% (P < 0.0001, but at the cost of a significant reduction in CTA QI (2.0 ± 1.0 vs. 0.8 ± 0.4, P < 0.0044). CTA QI is a simple, reproducible metric of image quality suited for comparing CTA studies. Using this quality index, we establish that CTA performed with wide-detector scan techniques can yield substantially lower radiation dose without compromising diagnostic imaging quality. A wide-detector target technique can further reduce effective dose compared to wide-detector retrospective ECG-synchronization, but with a reduction in image quality.

Effect of a dedicated PI-QUAL curriculum on the assessment of prostate MRI quality

Предложен и обоснован новый метод многокритериальной оценки качества цифрового изображения молочной железы. Разработаны шкалы интегральных оценок качества маммограммы, в основу которых кроме субъективных критериев положены объективные характеристики маммографического изображения. С использованием разработанных шкал врачи-рентгенологи оценивают качество конкретного маммографического снимка. Для сравнения усредненных оценок качества маммографического изображения, полученного в результате обработки различными методами, предлагается использовать различные критерии оптимальности в условиях неопределенности.

PurposeTo assess the impact of prostate MRI image quality by means of the Prostate Imaging Quality (PI-QUAL) score, on the identification of extraprostatic extension of disease (EPE), predicted using the EPE Grade Score, Likert Scale Score (LSS) and a clinical nomogram (MSKCCn). MethodsWe retrospectively included 105 patients with multiparametric prostate MRI prior to prostatectomy. Two radiologists evaluated image quality using PI-QUAL (≥4 was considered high quality) in consensus. All cases were also scored using the EPE Grade, the LSS, and the MSKCCn (dichotomized). Inter-rater reproducibility for each score was also assessed. Accuracy was calculated for the entire population and by image quality, considering two thresholds for EPE Grade (≥2 and = 3) and LSS (≥3 and ≥ 4) and using McNemar’s test for comparison. ResultsOverall, 66 scans achieved high quality. The accuracy of EPE Grade ranged from 0.695 to 0.743, while LSS achieved values between 0.705 and 0.733. Overall sensitivity for the radiological scores (range = 0.235–0.529) was low irrespective of the PI-QUAL score, while specificity was higher (0.775–0.986). The MSKCCn achieved an AUC of 0.76, outperforming EPE Grade (=3 threshold) in studies with suboptimal image quality (0.821 vs 0.564, p = 0.016). EPE Grade (=3 threshold) accuracy was also better in high image quality studies (0.849 vs 0.564, p = 0.001). Reproducibility was good to excellent overall (95 % Confidence Interval range = 0.782–0.924). ConclusionAssessing image quality by means of PI-QUAL is helpful in the evaluation of EPE, as a scan of low quality makes its performance drop compared to clinical staging tools.

PurposeThis study presents MZ CUBE, a newly developed multipurpose phantom designed to assess both image quality and geometrical accuracy in image‐guided radiotherapy.MethodsThe phantom is a 16 × 16 × 16 cm3 cube made of acrylonitrile butadiene styrene and designed to evaluate HU constancy, HU uniformity, spatial integrity, spatial resolution, low contrast resolution, and geometrical accuracy. Two CT simulators (Big Bore RT and Discovery RT Gen3) and two cone‐beam CT (CBCT) systems (XVI and OBI) were used for verification alongside commercial phantoms (ACR 464 and CatPhan 504).ResultsHU constancy differences were within 3 HU, and uniformity was within 1 HU for CT and 2 HU for CBCT, based on repeated MZ CUBE measurements. Spatial resolution with the MZ CUBE was 7 lp/cm (Big Bore RT), 8 lp/cm (Discovery RT Gen3), 7 lp/cm (XVI), and 8 lp/cm (OBI). The minimum discernible disk diameters were 7, 5, 6, and 6 mm, respectively. Geometrical accuracy was confirmed with translational offsets below 1 mm and rotational deviations below 0.2° for both CBCT systems.ConclusionsMZ CUBE enables comprehensive image quality and geometric accuracy evaluation in a single scan, offering an efficient and cost‐effective solution for radiotherapy QA.

The American College of Radiology's (ACR) Nuclear Medicine and PET Accreditation Programs evaluate qualifications of personnel, equipment, image quality, and quality control measures. It is believed that these are primary factors that impact the quality of patient imaging. The ACR accreditation allows facilities to critique and improve their practices as part of their preparation for the accreditation evaluation process. The goals of the ACR Nuclear Medicine and PET Accreditation Programs are improvement in the quality of imaging, provision of educational information by raising awareness of imaging issues, and the recognition of imaging facilities which meet program objectives. This presentation will outline the program requirements, highlighting some of the common pitfalls that may cause deficiencies in both the clinical and phantom submissions.This presentation will provide participants with:1. General information describing the ACR Accreditation Programs2. Information about the Diagnostic Modality Accreditation Programs3. Specific information about the ACR Nuclear Medicine and PET Accreditation Program, to include the application process, clinical images submission and quality control requirements.

PurposeTo evaluate and compare the image quality and diagnostic accuracy of Artificial Intelligence-assisted Compressed Sensing (ACS) sequences for lumbar disease, as an acceleration method for MRI combining parallel imaging, half-Fourier, compressed sensing and neural network and routine 2D sequences for lumbar spine.MethodsWe collected data from 82 healthy subjects and 213 patients who used 2D ACS accelerated sequences to examine the lumbar spine while 95 healthy subjects and 234 patients used routine 2D sequences. Acquisitions included axial T2WI, sagittal T2WI, T1WI, and T2-fs sequences. All obtained images of these subjects were analyzed in the light of calculating image quality factors such as signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for selected regions of interest. The lumbar image quality, artifacts and visibility of lesion structure were assessed by two radiologists independently. Differences between the evaluation values above were tested for statistical significance by the Wilcoxon signed-ranks test. Inter-observer agreements of image quality between two radiologists were measured using Cohen’s kappa correlation coefficient.ResultsThe ACS accelerated sequences not only reduced the scanning time by 18.9%, but also retained basically the same image quality as the routine 2D sequences in both healthy subjects and patients. Artifacts are less produced on ACS accelerated sequences compared with routine 2D sequences (p < 0.05). Apart from this, there were no significant differences in quantitative SNR, CNR measurements and qualitative scores within reviewing radiologists for each group (p > 0.05). Moreover, inter-observer agreement between two radiologists in scoring image quality was substantial consistently for ACS accelerated sequences and routine sequences (kappa = 0.622–0.986).ConclusionCompared with routine 2D sequences, ACS accelerated sequences allow for faster lumbar spine imaging with similar imaging quality and present reliable diagnostic accuracy, which can potentially improve workflow and patient comfort in musculoskeletal examinations.

Forensic oral imaging quality of hand-held dental X-ray devices: Comparison of two image receptors and two devices

An optimized CNN-based quality assessment model for screen content image

Quantitative Assessment of Image Quality in 64-slice-computed Tomography of Coronary Arteries in Subjects Undergoing Screening for Coronary Artery Disease

영상 처리 및 컴퓨터 비전 분야에 있어서, 평균 제곱 오차(Mean Squared Error: MSE)는 좋은 수학적 특성(예를 들어, 척도성(metricability), 미분가능성(differentiability) 및 볼록 성질(convexity))을 가짐으로 인해 많은 영상 화질 최적화 문제의 객관적 척도로 사용되어 왔다. 그러나 MSE가 영상의 왜곡 신호에 대한 시각적 인지 화질과 상관도가 높지 않다는 것이 알려지면서, 이를 해결하기 위해 위에서 언급한 좋은 수학적 특성과 높은 영상 화질 예측 성능을 동시에 가지는 객관적 영상 화질 측정(Image Quality Assessment: IQA)척도가 활발히 연구되어 왔다. 비록 최근 제안된 좋은 수학적 성질을 만족시키는 IQA 척도들은 MSE와 비교하여 매우 향상된 주관적 화질 예측 성능을 보이지만, 상대적으로 높은 계산 복잡도를 가진다. 본 논문은 이를 해결하기 위해, 단순 라플라스 연산자를 이용한 좋은 수학적 특성을 가지는 새로운 IQA 척도를 제안한다. 제안 IQA 방법에 도입한 단순 라플라스 연산자는 인간 시각 체계의 망막에서의 광도 자극에 대한 시신경 반응을 효과적으로 모사할 뿐만 아니라 계산이 매우 단순하기 때문에, 제안 IQA 척도는 단순 라플라스 연산자를 사용하여 매우 빠른 계산 속도와 높은 주관적 화질 점수 예측력을 확보하였다. 제안 IQA 척도의 효과를 검증하기 위해, 최신 IQA 척도들과 광범위한 성능비교 실험을 수행하였다. 실험 결과, 제안하는 IQA 척도는 모든 테스트 IQA 척도들 중 MSE를 제외하고 가장 빠른 처리 속도를 보였을 뿐만 아니라, 가장 높은 주관적 화질예측 성능을 보였다. In image processing and computer vision fields, mean squared error (MSE) has popularly been used as an objective metric in image quality optimization problems due to its desirable mathematical properties such as metricability, differentiability and convexity. However, as known that MSE is not highly correlated with perceived visual quality, much effort has been made to develop new image quality assessment (IQA) metrics having both the desirable mathematical properties aforementioned and high prediction performances for subjective visual quality scores. Although recent IQA metrics having the desirable mathematical properties have shown to give some promising results in prediction performance for visual quality scores, they also have high computation complexities. In order to alleviate this problem, we propose a new fast IQA metric using a simple Laplace operator. Since the Laplace operator used in our IQA metric can not only effectively mimic operations of receptive fields in retina for luminance stimulus but also be simply computed, our IQA metric can yield both very fast processing speed and high prediction performance. In order to verify the effectiveness of the proposed IQA metric, our method is compared to some state-of-the-art IQA metrics. The experimental results showed that the proposed IQA metric has the fastest running speed compared the IQA methods except MSE under comparison. Moreover, our IQA metric achieves the best prediction performance for subjective image quality scores among the state-of-the-art IQA metrics under test.

Zirconium-89 (t(1/2)=78.41 hours) is an ideal metallic radioisotope for immuno-positron emission tomography (PET), given that its physical half-life closely matches the biological half-life of monoclonal antibodies. In this study, the authors measured the spatial resolution and image quality of Zr-89 PET and compared the results against those obtained using F-18 PET, which is widely regarded as the gold standard for comparison of imaging characteristics. The spatial resolution and image qualities of Zr-89 were measured on the Siemens Biograph Truepoint TrueV PET/CT scanner, partly according to NEMA NU2-2007 standards. For spatial resolution measurement, the Zr-89 point source was located at the center of the axial field of view (FOV) and offset 1/4 axial FOV from the center. For image quality measurements, an NEMA IEC Phantom was used. The NEMA IEC Phantom consists of six hot spheres that were filled with Zr-89 solution. Spatial resolution and image quality (%contrast, %background variability [BV], and source to background ratio [SBR]) were assessed to compare the imaging characteristics of F-18 with those of Siemens Biograph Truepoint TrueV. The transverse and axial spatial resolutions at 1 cm were 4.5 and 4.7 mm for Zr-89, respectively. The %contrast of Zr-89 was 25.5% for the smallest 10 mm sized sphere and 89.8% for the largest 37 mm sized sphere, and for F-18, it was 32.5% for the smallest 10 mm sized sphere and 103.9% for the largest 37 mm sized sphere using the ordered subset expectation maximization (OSEM) reconstruction method. The %BV of F-18 PET was 6.4% for the smallest 10 mm sized sphere and 3.5% for the largest 37 mm sized sphere using the OSEM reconstruction. The SBR of Zr-89 was 1.8 for the smallest 10 mm sized sphere and 3.7 for the largest 37 mm sized sphere, and for F-18, it was 2.0 for the smallest 10 mm sized sphere and 4.1 for the largest 37 mm sized sphere using the OSEM reconstruction method. This study assessed Zr-89 imaging characteristics using a Siemens Biograph Truepoint TrueV PET/CT scanner and compared the results with those obtained for F-18 PET. Although spatial resolution and image quality of Zr-89 PET were lower compared with F-18 PET, due to longer positron range and low positron branching ratio, Zr-89 is advantageous for immuno-PET due to well-matched half-life with monoclonal antibodies.

Ferumoxytol is becoming more widely used as an off-label blood-pool contrast agent for MR angiography (MRA) and four-dimensional (4D) flow imaging in pediatric cardiovascular disease. Brand and generic versions of ferumoxytol are available with no information on relative efficacy as a contrast agent and safety profiles. This study evaluates patient safety and image quality of comparable dosages of generic ferumoxytol (GF) versus brand ferumoxytol (BF) with the following hypotheses: (1) Reducing the contrast dosage from 3 to 2mg/kg will not affect imaging quality and diagnostic accuracy of MRA and four-dimensional 4D flow. (2) GF and BF have similar image quality. (3) GF and BF have similar patient safety profiles. In an IRB-approved retrospective study, changes in vitals/clinical status between baseline, during infusion, and 30min post-infusion were analyzed in 3 groups: group 1 (3mg/kg BF, 216 patients, age: 19.29 ± 11.71years ranging from 2months to 62years), group 2 (2mg/kg BF, 47 patients, age: 15.35 ± 8.56years ranging from 10days to 41years), and group 3 (2mg/kg GF, 127 patients, age: 17.16 ± 12.18years ranging from 6days to 58years). Both pediatric and adult patients with congenital heart disease (CHD) indications were included within the study. Adverse reactions were classified as mild, moderate, or severe. Quantitative analysis of MR image quality was performed with signal-to-noise ratio (SNR) on MRA and velocity-to-noise ratio (VNR) on 4D flow. Qualitative grading of imaging features was performed by 2 experienced observers. Two-way analysis of variance (ANOVA) and chi-square tests were used for comparison with a P value of ≤ 0.05 used for significance. No statistical difference was found in clinical status and vital signs (P>0.05). No severe reactions were reported. 7.9% of GF patients experienced an adverse reaction compared to 2.3% with 3mg/kg BF and 8.4% with 2mg/kg BF. There was no statistical difference in SNR between the 3 groups (P>0.05). For 4D flow, 2mg/kg GF demonstrated an increase in VNR compared to 2mg/kg BF (P = 0.005). The qualitative scores for MRA and 4D flow were high (≥ 3) across all 3 groups. No significant difference was identified between 2mg/kg GF and BF in terms of safety profile and image quality. Given the small sample size of this study, further studies are required to confirm these results.