Lower-extremity muscle wasting in patients with peripheral arterial disease: quantitative measurement and evaluation with CT.

OBJECTIVES: Lower-extremity peripheral arterial disease (PAD) results in limb ischemia and is strongly associated with sarcopenia. This study aimed to retrospectively evaluate the association between the quantity of muscle mass in the lower extremities and the severity of vascular stenosis in PAD patients. METHODS: Between January 2018 and August 2021, 128 patients with PAD and 53 individuals without PAD, diagnosed by computed tomography, were enrolled. The severity of stenosis of lower-extremity arteries was measured using a grading system. The muscle and fat mass areas were calculated in the abdomen at the L3 or L4 level, mid-thigh, and lower leg. Multivariable logistic regression was conducted to clarify the risk associated with low muscle mass. The difference in muscle mass between PAD and non-PAD patients was evaluated by using propensity score matching. RESULTS: A strong positive correlation between the abdomen muscle area and leg muscle area was observed. The muscle area and muscle index of the leg were lower in PAD patients. These changes occurred earlier than in the abdomen muscle area. The group with more severe artery stenosis had more muscle wasting in the lower extremities. Greater age, female, lower BMI, and PAD were associated with low muscle mass. After propensity score matching, the leg muscle area was still lower in PAD patients. CONCLUSIONS: There is a direct association between PAD and regional muscle wasting. This occurs earlier regionally in the lower extremities than in central muscles. Early diagnosis of PAD might prevent progressive muscle loss, improving disease outcome and quality of life. KEY POINTS: • Peripheral arterial disease is strongly associated with sarcopenia. • Muscle wasting in the lower extremities is earlier and more prominent than that in the abdomen. • More severe arterial stenoses are associated with higher muscle wasting in the lower extremities.

Deep learning-based denoising in projection-domain and reconstruction-domain for low-dose myocardial perfusion SPECT.

BACKGROUND: Low-dose (LD) myocardial perfusion (MP) SPECT suffers from high noise level, leading to compromised diagnostic accuracy. Here we investigated the denoising performance for MP-SPECT using a conditional generative adversarial network (cGAN) in projection-domain (cGAN-prj) and reconstruction-domain (cGAN-recon). METHODS: Sixty-four noisy SPECT projections were simulated for a population of 100 XCAT phantoms with different anatomical variations and 99mTc-sestamibi distributions. Series of LD projections were obtained by scaling the full dose (FD) count rate to be 1/20 to 1/2 of the original. Twenty patients with 99mTc-sestamibi stress SPECT/CT scans were retrospectively analyzed. For each patient, LD SPECT images (7/10 to 1/10 of FD) were generated from the FD list mode data. All projections were reconstructed by the quantitative OS-EM method. A 3D cGAN was implemented to predict FD images from their corresponding LD images in the projection- and reconstruction-domain. The denoised projections were reconstructed for analysis in various quantitative indices along with cGAN-recon, Gaussian, and Butterworth-filtered images. RESULTS: cGAN denoising improves image quality as compared to LD and conventional post-reconstruction filtering. cGAN-prj can further reduce the dose level as compared to cGAN-recon without compromising the image quality. CONCLUSIONS: Denoising based on cGAN-prj is superior to cGAN-recon for MP-SPECT.

Quantitative Assessment of Lipiodol-Related Artifact Reduction for Dual-Energy Computed Tomography After Transcatheter Arterial Chemoembolization: A Phantom Study Evaluating the Use of Metal Artifact Reduction Algorithms.

OBJECTIVE: This study used metal artifact reduction (MAR) software to examine the computed tomography (CT) number of dual-energy CT (DECT) of hepatocellular carcinoma after transcatheter arterial chemoembolization. METHODS: Hollow columnar acrylic phantoms were filled with lipiodol and inserts of 2 sizes (large and small) were used to simulate liver tumors on a Revolution GSI CT scanner. The CT numbers of a single test object were collected twice: once with and once without the MAR algorithm. Lipiodol beam-hardening artifacts were quantified by measuring CT numbers in a region of interest around the tumor-simulating insert. RESULTS: The virtual monochromatic CT numbers of large and small tumors were closely related to energy. For small tumors, CT numbers increased with energy. For large tumors, CT numbers increased with energy at 1 cm from the margin but decreased with an increase in energy at 5 cm. Regardless of the size, distance, or location of the tumor, the CT numbers fluctuated more at low energy levels. CONCLUSIONS: At 1 cm from the margin, the CT numbers with MAR were significantly different from those without MAR. Low-energy CT numbers with MAR were near reference values. Metal artifact reduction exhibited superior performance for small tumors. Tumor margin images are affected by artifacts caused by Lipiodol. However, with MAR, CT numbers can be effectively calibrated, thus enabling clinicians to more accurately evaluate hepatocellular carcinoma development and identify residual tumors and recurrent or metastatic lesions.

Improvements in Left Ventricular Diastolic Mechanics After Parachute Device Implantation in Patients With Ischemia Heart Failure: A Cardiac Computerized Tomographic Study.

BACKGROUND: Percutaneous ventricular restoration therapy with the use of a left ventricle (LV)-partitioning Parachute device has emerged as a clinical treatment option for LV apical aneurysm after extensive anterior myocardial infarction (AMI). We assessed changes of diastolic mechanics and functional improvements following LV Parachute device implantation by means of cardiac computerized tomography (CCT). METHODS AND RESULTS: CCT data were obtained from 28 patients before and after LV Parachute device implantation. Diastolic functional indices were determined by means of quantitative CCT assessment: 1) transmitral velocities in early (E) and late (A) diastole and ratio (E/A); 2) early diastolic mitral septal tissue velocity (Ea) and E/Ea; and 3) vortex formation time (VFT). Functional improvements were assessed with the use of New York Heart Association (NYHA) functional classification. Among the study patients, there were no significant differences in all transmitral velocities and E/A, though there was significantly increased Ea, reduced E/Ea, and greater VFT 6 months after LV Parachute device implantation. Finally, the improvement of diastolic functional indices after Parachute treatment correlated with observed clinical functional alterations (Δ E/Ea and Δ NYHA functional class:, r = 0.563; P = .002; Δ VFT and Δ NYHA functional class: r = -0.507; P = .006). CONCLUSIONS: LV Parachute device implantation therapy in heart failure caused by AMI and LV apical aneurysm formation showed improvements in several diastolic functional mechanics according to CCT-based measures.

Characteristic Features on Morphologic and Topographic Findings of Pulmonary Vein Orifices in Transition From Diastolic Dysfunction to Heart Failure: A Computerized Tomography Study.

BACKGROUND: Diastolic dysfunction (DD), a precursor to clinical heart failure (HF), has traditionally been evaluated by means of echocardiography. Data regarding morphologic descriptions of pulmonary vein (PV) orifices in transition from DD to HF have been lacking. METHODS AND RESULTS: We retrospectively studied 124 subjects with computerized tomography (CT)-derived PV parameters and echocardiography-derived diastolic indices. We categorized our subjects as 1) non-DD, 2) DD, or 3) heart failure with preserved ejection fraction (HFpEF) and observed a graded enlargement for 4 PV orifice areas across these groups. Positive linear relationship between the 4 PV orifice areas, echocardiography-derived mean pulmonary capillary wedge pressure (PCWP), and velocity of propagation (VP) were observed. Finally, maximum areas of left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV) significantly increased clinical diagnosis of HFpEF (likelihood-ratio χ(2): from 42.92 to 50.75 and 54.67 for LSPV and LIPV, respectively) when superimposed on left ventricular mass index, PCWP, and left atrial volume. CONCLUSIONS: PV size measurements with the use of CT are feasible and further aid in diseases discrimination between preclinical DD and those progressed into HF, even with preserved global pumping. Our data suggest that CT-based PV measures may help to identify subjects at risk for HF.

Interpolated average CT for cardiac PET/CT attenuation correction.

BACKGROUND: Previously, we proposed interpolated averaged CT (IACT) for improved attenuation correction (AC) in thoracic PET/CT. This study aims to evaluate its feasibility and effectiveness on cardiac PET/CT. METHODS: We simulated (18)F-FDG distribution using the XCAT phantom with normal and abnormal cardiac uptake. Average activity and attenuation maps represented static PET and respiration average CT (ACT), respectively, while the attenuation maps of end-inspiration/expiration represented 2 helical CTs (HCT). IACT was obtained by averaging the 2 extreme phases and the interpolated phases generated between them. Later, we recruited 4 patients who were scanned 1 hr post 315-428 MBq (18)F-FDG injection. Simulated and clinical PET sinograms were reconstructed with AC using (1) HCT, (2) IACT, and (3) ACT. Polar plots and the 17-segment plots were analyzed. Two regions-of-interest were drawn on lesion and background area to obtain the intensity ratio (IR). RESULTS: Polar plots of PETIACT-AC were more similar to PETACT-AC in both simulation and clinical data. Artifacts were observed in various segments in PETHCT-AC. IR differences of HCT as compared to the phantom were up to ~20%. CONCLUSIONS: IACT-AC reduced respiratory artifacts and improved PET/CT matching similarly to ACT-AC. It is a promising low-dose alternate of ACT for cardiac PET/CT.

The association among MDCT-derived three-dimensional visceral adiposities on cardiac diastology and dyssynchrony in asymptomatic population.

BACKGROUND: Visceral adipose tissue, a biologically active fat depot, has been proposed as a reliable marker for visceral adiposity and metabolic abnormalities. Effects of such adiposity on LV diastolic function and dyssynchrony remained largely unknown. METHODS: We assessed pericardial fat (PCF) and thoracic peri-aortic fat (TPAF) by three-dimensional (3D) volume-vender multi-detector computed tomography (MDCT) (Aquarius 3D Workstation, TeraRecon, San Mateo, CA, USA). Echo-derived diastolic parameters and tissue Doppler imaging (TDI) defined mitral annular systolic (S'), early diastolic (E') velocities as well as LV filling (E/E') were all obtained. Intra-ventricular systolic (Sys-D) and diastolic (Dias-D) dyssynchrony were assessed by TDI method. RESULTS: A total of 318 asymptomatic subjects (mean age: 53.5 years, 36.8 % female) were eligible in this study. Greater PCF and TPAF were both associated with unfavorable diastolic indices and higher diastolic dyssynchrony (all p < 0.05). These associations remained relatively unchanged in multi-variate models. PCF and TPAF set at 81.68 & 8.11 ml yielded the largest sensitivity and specificity (78.6 and 60 % for PCF, 75 and 66.6 % for TPAF, respectively) in predicting abnormally high LV diastolic dyssynchrony, which was defined as Dias-D≧55 ms. CONCLUSION: Increasing visceral adiposity may be associated with adverse effects on myocardium, primarily featured by worse diastolic function and greater degree of dyssynchrony.

Qualitative and semi-quantitative evaluation of myocardium perfusion with 3 T stress cardiac MRI.

BACKGROUND: 3 T MRI has been adopted by some centers as the primary choice for assessment of myocardial perfusion over conventional 1.5 T MRI. However, there is no data published on the potential additional value of incorporating semi-quantitative data from 3 T MRI. This study sought to determine the performance of qualitative 3 T stress magnetic resonance myocardial perfusion imaging (3 T-MRMPI) and the potential incremental benefit of using a semi-quantitative perfusion technique in patients with suspected coronary artery disease (CAD). METHODS: Fifty eight patients (41 men; mean age: 59 years) referred for elective diagnostic angiography underwent stress 3 T MRMPI with a 32-channel cardiac receiver coil. The MR protocol included gadolinium-enhanced stress first-pass perfusion (0.56 mg/kg, dipyridamole), rest perfusion, and delayed enhancement (DE). Visual analysis was performed in two steps. Ischemia was defined as a territory with perfusion defect at stress study but no DE or a territory with DE but additional peri-infarcted perfusion defect at stress study. Semi-quantitative analysis was calculated by using the upslope of the signal intensity-time curve during the first pass of contrast medium during dipyridamole stress and at rest. ROC analysis was used to determine the MPRI threshold that maximized sensitivity. Quantitative coronary angiography served as the reference standard with significant stenosis defined as >70 % diameter stenosis. Diagnostic performance was determined on a per-patient and per-vessel basis. RESULTS: Qualitative assessment had an overall sensitivity and specificity for detecting significant stenoses of 77 % and 80 %, respectively. By adding MPRI analysis, in cases with negative qualitative assessment, the overall sensitivity increased to 83 %. The impact of MPRI differed depending on the territory; with the sensitivity for detection of left circumflex (LCx) stenosis improving the most after semi-quantification analysis, (66 % versus 83 %). CONCLUSIONS: Pure qualitative assessment of 3 T MRI had acceptable performance in detecting severe CAD. There is no overall benefit of incorporating semi-quantitative data; however a higher sensitivity can be obtained by adding MPRI, especially in the detection of LCx lesions.

Dosimetry and efficiency comparison of knowledge-based and manual planning using volumetric modulated arc therapy for craniospinal irradiation.

BACKGROUND: Craniospinal irradiation (CSI) poses a challenge to treatment planning due to the large target, field junction, and multiple organs at risk (OARs) involved. The aim of this study was to evaluate the performance of knowledge-based planning (KBP) in CSI by comparing original manual plans (MP), KBP RapidPlan initial plans (RPI), and KBP RapidPlan final plans (RPF), which received further re-optimization to meet the dose constraints. PATIENTS AND METHODS: Dose distributions in the target were evaluated in terms of coverage, mean dose, conformity index (CI), and homogeneity index (HI). The dosimetric results of OARs, planning time, and monitor unit (MU) were evaluated. RESULTS: All MP and RPF plans met the plan goals, and 89.36% of RPI plans met the plan goals. The Wilcoxon tests showed comparable target coverage, CI, and HI for the MP and RPF groups; however, worst plan quality was demonstrated in the RPI plans than in MP and RPF. For the OARs, RPF and RPI groups had better dosimetric results than the MP group (P < 0.05 for optic nerves, eyes, parotid glands, and heart). The planning time was significantly reduced by the KBP from an average of 677.80 min in MP to 227.66 min (P < 0.05) and 307.76 min (P < 0.05) in RPI, and RPF, respectively. MU was not significantly different between these three groups. CONCLUSIONS: The KBP can significantly reduce planning time in CSI. Manual re-optimization after the initial KBP is recommended to enhance the plan quality.

How far can the radiation dose be lowered in head CT with iterative reconstruction? Analysis of imaging quality and diagnostic accuracy.

OBJECTIVE: To evaluate the imaging quality of head CT at lowered radiation dose by combining filtered back projection (FBP) and iterative reconstruction (IR) algorithms. METHODS: Experimental group A (n = 66) underwent CT with 43 % tube current reduction, and group B (n = 58) received an equivalent reduced dose by lowering the tube voltage. An age- and sex-matched control group (n = 72) receiving the conventional radiation dose was retrospectively collected. Imaging for the control group was reconstructed by FBP only, while images for groups A and B were reconstructed by FBP and IR. The signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), sharpness, number of infarcts and severity of subcortical arteriosclerotic encephalopathy (SAE) were compared to assess imaging quality and diagnostic accuracy. RESULTS: There were no significant differences in SNRs and CNRs between group A and the control group. There were significantly decreased SNRs and increased CNRs in group B. Image sharpness decreased in both groups. Correlations between detected infarcts and severity of SAE across FBP and IR were high (r = 0.73-0.93). Head diameter was the only significant factor inversely correlated with infratentorial imaging quality. CONCLUSION: Head CT with 43 % reduced tube current reconstructed by IR provides diagnostic imaging quality for outpatient management. KEY POINTS: • Cranial CT using iterative reconstruction provides diagnostic images with 43 % mAs reduction. • Blurring of infratentorial images becomes evident using low-radiation head CT. • Head diameter was inversely correlated with imaging quality in the infratentorium. • Lowering tube kilovoltage requires a higher radiation dose to maintain image quality.

High pericardial and peri-aortic adipose tissue burden in pre-diabetic and diabetic subjects.

BACKGROUND: Central obesity in relation to insulin resistance is strongly linked to the development of type 2 diabetes. However, data regarding the association between pericardial and peri-aortic adiposity, a potential estimate of visceral adipose tissue burden, and pre-diabetes status remains unclear.The aim of this study was to examine whether the degree of pericardial and thoracic peri-aortic adipose tissue, when quantified by multi-detector computed tomography (MDCT), differs significantly in a normal, pre-diabetic, and overtly diabetic population. METHODS: We studied 562 consecutive subjects including 357 healthy, 155 pre-diabetic, and 50 diabetic patients selected from participants who underwent annual health surveys in Taiwan. Pre-diabetes status was defined by impaired fasting glucose or impaired glucose intolerance according to American Diabetes Association guidelines. Pericardial (PCF) and thoracic peri-aortic (TAT) adipose tissue burden was assessed using a non-contrast 16-slice multi-detector computed tomography (MDCT) dataset with off-line measurement (Aquarius 3D Workstation, TeraRecon, San Mateo, CA, USA). Body fat composition, serum high-sensitivity C-reactive protein (hs-CRP) level and insulin resistance (HOMA-IR) were also assessed. RESULTS: Patients with diabetes and pre-diabetes had greater volume of PCF (89 ± 24.6, 85.3 ± 28.7 & 67.6 ± 26.7 ml, p < 0.001) as well as larger TAT (9.6 ± 3.1 ml vs 8.8 ± 4.2 & 6.6 ± 3.5 ml, respectively, p < 0.001) when compared to the normal group, although there were no significant differences in adiposity between the diabetic and pre-diabetic groups. For those without established diabetes in our study, increasing TAT burden, but not PCF, appear to correlate with insulin resistance (HOMA-IR) and hs-CRP in the multivariable models. CONCLUSIONS: Pre-diabetic and diabetic subjects, compared to normoglycemia, were associated with significantly higher pericardial and peri-aortic adipose tissue burden. In addition, visceral fat accumulation adjacent to the thoracic aorta seemed to exert a significant impact on insulin resistance and systemic inflammation.

Quantitative flow measurement by digital subtraction angiography in cerebral carotid stenosis using optical flow method.

OBJECTIVE: We analyzed intracranial regional blood flows using an optical flow method (OFM) and digital subtraction angiography in patients with internal carotid artery (ICA) stenosis. We also retrospectively explored the correlation between the patients' diagnoses and the severity of the ICA stenoses. MATERIALS AND METHODS: OFM, an image-processing algorithm to estimate motion, was applied to determine the mean velocity V(mean) in the vessels. A group of 40 patients without vascular anomalies acted as the control group. The patients were classified as having either moderate stenosis (< 80%, n=14) or severe stenosis (> 80%, n=23). RESULTS: The V(mean) of the ICAs was significantly lower in the stenotic group compared with the control group (p< 0.01). The V(mean) of the ICAs was inversely correlated with the severity of the stenosis (p< 0.05). The receiver operating characteristic curve of the V(mean) in an AP view showed substantial discriminatory power, with an optimal cutoff value of 3.48 pixels/frame for the detection of patients with carotid stenosis. The sensitivity and specificity were 84% and 50%, respectively. On a lateral view, the best cutoff for the V(mean) was 4.01 pixels/frame, and the sensitivity and specificity were 92% and 43%, respectively. CONCLUSIONS: Digital subtraction angiography combined with the OFM is a feasible parametric method for intracranial blood flow measurements in patients with moderate to severe carotid stenosis.

Evaluation of the cardiac subvolume dose and myocardial perfusion in left breast cancer patients with postoperative radiotherapy: a prospective study.

Adjuvant breast radiotherapy could reduce the risk of local recurrence. However, the radiation dose received by the heart also increases the risk of cardiotoxicity and causes consequential heart diseases. This prospective study aimed to evaluate more precisely cardiac subvolume doses and corresponding myocardial perfusion defects according to the American Heart Association (AHA)'s 20-segment model for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) interpretation for breast cancer after radiotherapy. The 61 female patients who underwent adjuvant radiotherapy following breast cancer surgery for left breast cancer were enrolled. SPECT MPI were performed before radiotherapy for baseline study, and 12 months after for follow-up. Enrolled patients were divided into two groups, new perfusion defect (NPD) and non new perfusion defect found (non-NPD) according to myocardial perfusion scale score. CT simulation data, radiation treatment planning, and SPECT MPI images were fused and registered. The left ventricle was divided into four rings, three territories, and 20 segments according to the AHA's 20-segment model of the LV. The doses between NPD and non-NPD groups were compared by the Mann-Whitney test. The patients were divided into two groups: NPD group (n = 28) and non-NPD group (n = 33). The mean heart dose was 3.14 Gy in the NPD group and 3.08 Gy in the non-NPD group. Mean LV doses were 4.84 Gy and 4.71 Gy, respectively. The radiation dose of the NPD group was higher than the non-NPD group in the 20 segments of LV. There was significant difference in segment 3 (p = 0.03). The study indicated that the radiation doses to 20 segments of LV in NPD were higher than those in non-NPD significantly at segment 3, and higher in other segments in general. In the bull's eye plot combining radiation dose and NPD area, we found that the new cardiac perfusion decline may exist even in the low radiation dose region.Trial registration: FEMH-IRB-101085-F. Registered 01/01/2013, https://clinicaltrials.gov/ct2/show/NCT01758419?cond=NCT01758419&draw=2&rank=1 .

Fast myocardial perfusion SPECT denoising using an attention-guided generative adversarial network.

Purpose: Deep learning-based denoising is promising for myocardial perfusion (MP) SPECT. However, conventional convolutional neural network (CNN)-based methods use fixed-sized convolutional kernels to convolute one region within the receptive field at a time, which would be ineffective for learning the feature dependencies across large regions. The attention mechanism (Att) is able to learn the relationships between the local receptive field and other voxels in the image. In this study, we propose a 3D attention-guided generative adversarial network (AttGAN) for denoising fast MP-SPECT images. Methods: Fifty patients who underwent 1184 MBq 99mTc-sestamibi stress SPECT/CT scan were retrospectively recruited. Sixty projections were acquired over 180° and the acquisition time was 10 s/view for the full time (FT) mode. Fast MP-SPECT projection images (1 s to 7 s) were generated from the FT list mode data. We further incorporated binary patient defect information (0 = without defect, 1 = with defect) into AttGAN (AttGAN-def). AttGAN, AttGAN-def, cGAN, and Unet were implemented using Tensorflow with the Adam optimizer running up to 400 epochs. FT and fast MP-SPECT projection pairs of 35 patients were used for training the networks for each acquisition time, while 5 and 10 patients were applied for validation and testing. Five-fold cross-validation was performed and data for all 50 patients were tested. Voxel-based error indices, joint histogram, linear regression, and perfusion defect size (PDS) were analyzed. Results: All quantitative indices of AttGAN-based networks are superior to cGAN and Unet on all acquisition time images. AttGAN-def further improves AttGAN performance. The mean absolute error of PDS by AttcGAN-def was 1.60 on acquisition time of 1 s/prj, as compared to 2.36, 2.76, and 3.02 by AttGAN, cGAN, and Unet. Conclusion: Denoising based on AttGAN is superior to conventional CNN-based networks for MP-SPECT.

Integrating subvolume dose and myocardial perfusion imaging parameters to assess the impact of radiation therapy on heart function in breast cancer patients: A comparative analysis between left- and right-sided breast cancer.

BACKGROUND: This study aimed to utilize an innovative method of integrating the 20 subvolume dose of left ventricle and the Tl-201 single photon emission computed tomography (SPECT) with myocardial perfusion imaging (MPI) parameters in patients with left- and right-sided breast cancer after radiation therapy. METHODS: Female patients with breast cancer underwent SPECT MPI before commencing radiotherapy and 12 months later were enrolled from January 2014 to December 2018. The images of CT simulation and SPECT MPI were integrated into the treatment planning system. The differences of doses and parameters of MPI in all cardiac subvolumes between left- and right-sided breast cancer patients were analyzed. RESULTS: Patients with left-sided breast cancer (n = 61) received a higher radiation dose to the heart, left ventricular, and its territories and subvolumes, compared to patients with right-sided breast cancer (n = 19). The 20-segment analysis also showed statistically significant disparities in the average radiation doses received by the two groups. In different coronary artery territories, the end-diastolic perfusion and end-systolic perfusion showed a decrease in both sides, with no significant differences. However, the wall motion and wall thickening showed a significant decline in subregions within the left- and right-sided coronary artery territories. CONCLUSION: This study demonstrates an innovative integrated method combining the left ventricular 20 regional doses with SPECT MPI which shows that left-sided breast cancer patients receive a higher subvolume dose than right-sided breast cancer patients. Further research is needed to confirm the potential impact on heart function after radiotherapy on both sides.

Hazard-based risk grouping effectively stratifying breast cancer patients in post-irradiation long-term heart diseases: a population-based cohort study.

Background: Even though advanced radiotherapy techniques provide a better protective effect on surrounding normal tissues, the late sequelae from radiation exposure to the heart are still considerable in breast cancer patients. The present population-based study explored the role of cox-regression-based hazard risk grouping and intended to stratify patients with post-irradiation long-term heart diseases. Materials and methods: The present study investigated the Taiwan National Health Insurance (TNHI) database. From 2000 to 2017, we identified 158,798 breast cancer patients. Using a propensity score match of 1:1, we included 21,123 patients in each left and right breast irradiation cohort. Heart diseases, including heart failure (HF), ischemic heart disease (IHD), and other heart diseases (OHD), and anticancer agents, including epirubicin, doxorubicin, and trastuzumab, were included for analysis. Results: Patients received left breast irradiation demonstrated increased risks on IHD (aHR, 1.16; 95% CI, 1.06-1.26; p < 0.01) and OHD (aHR, 1.08; 95% CI, 1.01-1.15; p < 0.05), but not HF (aHR, 1.11; 95% CI, 0.96-1.28; p = 0.14), when compared with patients received right breast irradiation. In patients who received left breast irradiation dose of >6,040 cGy, subsequent epirubicin might have a trend to increase the risk of heart failure (aHR, 1.53; 95% CI, 0.98-2.39; p = 0.058), while doxorubicin (aHR, 0.59; 95% CI, 0.26-1.32; p = 0.19) and trastuzumab (aHR, 0.93; 95% CI, 0.33-2.62; p = 0.89) did not. Older age was the highest independent risk factor for post-irradiation long-term heart diseases. Conclusion: Generally, systemic anticancer agents are safe in conjunction with radiotherapy for managing post-operative breast cancer patients. Hazard-based risk grouping may help stratify breast cancer patients associated with post-irradiation long-term heart diseases. Notably, radiotherapy should be performed cautiously for elderly left breast cancer patients who received epirubicin. Limited irradiation dose to the heart should be critically considered. Regular monitoring of potential signs of heart failure may be conducted.

Machine learning combined with radiomics and deep learning features extracted from CT images: a novel AI model to distinguish benign from malignant ovarian tumors.

BACKGROUND: To develop an artificial intelligence (AI) model with radiomics and deep learning (DL) features extracted from CT images to distinguish benign from malignant ovarian tumors. METHODS: We enrolled 149 patients with pathologically confirmed ovarian tumors. A total of 185 tumors were included and divided into training and testing sets in a 7:3 ratio. All tumors were manually segmented from preoperative contrast-enhanced CT images. CT image features were extracted using radiomics and DL. Five models with different combinations of feature sets were built. Benign and malignant tumors were classified using machine learning (ML) classifiers. The model performance was compared with five radiologists on the testing set. RESULTS:  Among the five models, the best performing model is the ensemble model with a combination of radiomics, DL, and clinical feature sets. The model achieved an accuracy of 82%, specificity of 89% and sensitivity of 68%. Compared with junior radiologists averaged results, the model had a higher accuracy (82% vs 66%) and specificity (89% vs 65%) with comparable sensitivity (68% vs 67%). With the assistance of the model, the junior radiologists achieved a higher average accuracy (81% vs 66%), specificity (80% vs 65%), and sensitivity (82% vs 67%), approaching to the performance of senior radiologists. CONCLUSIONS:  We developed a CT-based AI model that can differentiate benign and malignant ovarian tumors with high accuracy and specificity. This model significantly improved the performance of less-experienced radiologists in ovarian tumor assessment, and may potentially guide gynecologists to provide better therapeutic strategies for these patients.

Peritherapeutic quantitative flow analysis of arteriovenous malformation on digital subtraction angiography.

BACKGROUND: Digital subtraction angiography (DSA) provides detailed hemodynamic information. However, the imaging interpretation is mainly based on the physician's experience and observation. We aimed to quantitatively study the peritherapeutic blood flow changes of a cerebral arteriovenous malformation (AVM) treated by embolization using optical flow estimation on DSA. METHODS: A 37-year-old woman with an AVM in the right frontal lobe of her brain was enrolled. The optical flow method with a pixel-by-pixel measurement was applied to determine the blood flow in brain vessels on anterior-posterior and lateral DSA views before and after embolization. RESULTS: A return toward normalization of blood flow as a result of embolization was determined semiquantitatively on the posttherapeutic DSA. CONCLUSIONS: Optical flow analysis on DSA illustrated the potential of quantifying intracranial blood flows in patients with cerebral vascular disorders and the therapeutic effects.

Pix2Pix generative adversarial network for low dose myocardial perfusion SPECT denoising.

Background: Myocardial perfusion (MP) SPECT is a well-established method for diagnosing cardiac disease, yet its radiation risk poses safety concern. This study aims to apply and evaluate the use of Pix2Pix generative adversarial network (Pix2Pix GAN) in denoising low dose MP SPECT images. Methods: One hundred male and female patients with different 99mTc-sestamibi activity distributions, organ and body sizes were simulated by a population of digital 4D Extended Cardiac Torso (XCAT) phantoms. Realistic noisy SPECT projections of full dose of 987 MBq injection and 16 min acquisition, and low dose ranged from 1/20 to 1/2 of the full dose, were generated by an analytical projector from the right anterior oblique (RAO) to the left posterior oblique (LPO) positions. Additionally, twenty patients underwent ~1,184 MBq 99mTc-sestamibi stress SPECT/CT scan were also retrospectively recruited for the study. For each patient, low dose SPECT images (7/10 to 1/10 of full dose) were generated from the full dose list mode data. Our Pix2Pix GAN model was trained with full dose and low dose reconstructed SPECT image pairs. Normalized mean square error (NMSE), structural similarity index (SSIM), coefficient of variation (CV), full-width-at-half-maximum (FWHM) and relative defect size differences (RSD) of Pix2Pix GAN processed images were evaluated along with a reference convolutional auto encoder (CAE) network and post-reconstruction filters. Results: NMSE values of 0.0233±0.004 vs. 0.0249±0.004 and 0.0313±0.007 vs. 0.0579±0.016 were obtained on 1/2 and 1/20 dose level for Pix2Pix GAN and CAE in the simulation study, while they were 0.0376±0.010 vs. 0.0433±0.010 and 0.0907±0.020 vs. 0.1186±0.025 on 7/10 and 1/10 dose level in the clinical study. Similar results were also obtained from the SSIM, CV, FWHM and RSD values. Overall, the use of Pix2Pix GAN was superior to other denoising methods in all physical indices, particular in the lower dose levels in the simulation and clinical study. Conclusions: The Pix2Pix GAN method is effective to reduce the noise level of low dose MP SPECT. Further studies on clinical performance are warranted to demonstrate its full clinical effectiveness.

Validation of Virtual Monochromatic Images and Effect of Body Size Obtained Using a Rapid kVp-switching Dual-energy Computed Tomography System: A Phantom Study.

ABSTRACT: The objective of this paper is to validate virtual monochromatic computed tomography (CT) numbers and the effect of the body size of insert materials in phantoms on the findings of a dual-energy CT scanner. The material inserted in the phantom simulates human organs. This study investigated the effect of different body sizes on CT numbers to understand the accuracy of dual-energy CT. The effect of body size on virtual monochromatic CT numbers was investigated using a QRM phantom. The true monochromatic CT numbers of insert materials were calculated from coefficients obtained using NIST XCOM. The true Z eff values were supplied by phantom manufacturers or computed using Mayneord's equation. The virtual monochromatic CT numbers of insert materials in both the phantoms varied with energy. The CT numbers of materials with a Z eff of >7.42 (water Z eff ) and <7.42 decreased and increased with energy, respectively. The CT numbers were affected by phantom size as a function of energy. For water, tissues, and air, the CT numbers in the XL phantom were considerably larger than those in other phantom sizes at 40 keV. Body size affected the CT numbers, particularly for the XL size and at low energies. For all materials, the magnitude of difference between the measured and true CT numbers was related to the Z eff of the materials, potentially because the photoelectric effect is more prominent at low energies for materials with a higher Z eff . The difference in CT numbers appeared to be dependent on position. The true and measured Z eff agreed to within 6% for all the materials except the SR2 brain, for which the discrepancy was 25%.