Purpose
The dual‐energy computed tomography (DECT) technique is an emerging imaging tool that can better characterize material features and has the potential to be a noninvasive means of predicting ...lymph node metastasis. The purpose of this study was to establish a DECT‐specified quantitative approach based on a neural network to characterize the sentinel lymph node (SLN).
Methods
With IRB approval, we retrospectively collected a total of 229 patients (100/229 metastasis) with biopsy proven breast cancer in this study. The chest and axillary spectral CT examinations were performed prior to the axillary lymph node (ALN) surgery. A decoupling convolution network with 11 ROIs from sequential keV (40 to 140 keV with 10 keV increment) was proposed to explicitly extract the spectral and spatial features in a DECT to predict the lymph node status. Focal loss was introduced as the loss function. The metric of the slope of the spectral Hounsfield unit curve measured at the venous phase was used as the baseline approach in comparison to our approach. In additional, a logistic model with radiomic features was also compared to our approach. The area under ROC curve (AUC) was used as the figure of merit to evaluate the classification performance.
Results
By introducing spectral convolution and focal loss, AUC on test set could be improved by 0.15 and 0.01 separately. Compared to the slope of the spectral curve with the average AUC of 0.611 and radiomic model with AUC of 0.825, the proposed approach demonstrates a considerably better performance, with test set AUC value of 0.837, by using decoupling spectral and spatial convolution together with focal loss function.
Conclusions
We presented a new decoupling neural network based quantification method for DECT analysis, which might have potential as a noninvasive tool to predict metastasis lymph node status for breast cancer in clinical practice.
This study investigates the potential of a machine learning classifier using dual‐ energy computed tomography (DECT) radiomics to differentiate between malignant pancreatic lesions and normal ...pancreas tissue. A total of 100 patients who underwent third‐generation DECT between November 2018 and October 2022 were included, with 60 patients having pancreatic cancer and 40 normal pancreatic tissue. Radiomics features were extracted from non‐contrast and arterial‐enhanced DECT scans with stepwise feature reduction used to identify relevant features. Thetrained machine learning classifiers achieved a diagnostic accuracy of 0.97 in the arterial‐enhanced model and 0.88 in non‐contrast scans with sensitivities of 0.97 and 0.96, respectively. Areas under the curve were 0.97 (95% CI, 0.92–1.0, p < 0.001) and 0.96 (95% CI, 0.90–1.0, p < 0.001), respectively with no significant differences between both models (p= 0.52). This approach shows promise in enhancing pancreatic cancer detection and improving patient diagnoses, particulary in specific patient groups.
Purpose
The stoichiometric calibration method for dual‐energy CT (DECT) proposed by Bourque et al. (Phys Med Biol. 59:2059; 2014), which provides estimators of the electron density and the effective ...atomic number, is adapted to a maximum a posteriori (MAP) framework to increase the model’s robustness to noise and biases in CT data, specifically for human tissues. Robust physical parameter estimation from noisy DECT scans is required to maximize the precision of quantities used for radiotherapy treatment planning such as the proton stopping power (SPR).
Methods
Estimation of electron density and effective atomic number is performed by constraining their variation to the natural range of values expected for human tissues, while maximizing attenuation data fidelity. The MAP framework is first compared against the original method using theoretical CT numbers with Gaussian noise. The quantitative accuracy of the MAP framework is then validated experimentally on the Gammex 467 phantom. Then, using two clinical datasets, the advantages of the approach are experimentally evaluated, qualitatively, and quantitatively.
Results
The theoretical study shows that the root‐mean‐square error on the electron density, the effective atomic number and the SPR are, respectively, reduced from 2.3 to 1.5, 5.7 to 3.2 and 2.8 to 1.7% with the adapted framework, when analyzing soft tissues and bone together. The experimental validation study shows that the standard deviation in Gammex inserts can be reduced, on average, by factors of 1.4 (electron density), 2.7 (effective atomic number), and 1.9 (SPR), while the quantitative accuracy of the three physical parameters is preserved, on average. Evaluation on clinical datasets show apparent noise reduction in maps of all estimated physical quantities, and suggests that the MAP framework has increased robustness to beam hardening and photon starvation artifacts. Mean values for the electron density, the effective atomic number, and the SPR averaged in four uniform regions of interest (brain, muscle, adipose, and cranium), respectively, differ by 0.7, 1.8, and 0.9% between both frameworks. The standard deviation in the same regions of interest is also reduced, on average, by factors of 1.8, 6.6, and 3.2 with the MAP framework. Differences in mean value and standard deviations are statistically significant.
Conclusion
Theoretical and experimental results suggest that the MAP framework produces more accurate and precise estimates of the electron density and SPR. Thus, the present approach limits the propagation of noise in DECT attenuation data to radiotherapy‐related parameters maps such as the SPR and the electron density. Using a MAP framework with DECT for radiotherapy treatment planning can help maximizing the precision of dose calculation. The method also provides more precise estimates of the effective atomic number. The MAP methodology is presented in a general way such that it can be adapted to any DECT image‐based tissue characterization method.
Predicting the risk of flares in patients with gout is a challenge and the link between urate burden and the risk of gout flare is unclear. The objective of this study was to determine if the extent ...of monosodium urate (MSU) burden measured with dual-energy computed tomography (DECT) and ultrasonography (US) is predictive of the risk of gout flares.
This prospective observational study recruited patients with gout to undergo MSU burden assessment with DECT (volume of deposits) and US (double contour sign) scans of the knees and feet. Patients attended follow-up visits at 3, 6 and 12 months. Patients having presented with at least one flare at 6 months were compared to those who did not flare. Odds ratios (ORs) (95% confidence interval) for the risk of flare were calculated.
Overall, 64/78 patients included attended at least one follow-up visit. In bivariate analysis, the number of joints with the double contour sign was not associated with the risk of flare (p = 0.67). Multivariate analysis retained a unique variable: DECT MSU volume of the feet. For each 1 cm
increase in DECT MSU volume in foot deposits, the risk of flare increased 2.03-fold during the first 6 months after initial assessment (OR 2.03 (1.15-4.38)). The threshold volume best discriminating patients with and without flare was 0.81 cm
(specificity 61%, sensitivity 77%).
This is the first study showing that the extent of MSU burden measured with DECT but not US is predictive of the risk of flares.
Purpose
This study developed methods to quantify and improve the accuracy of dual‐energy CT (DECT)‐based bone marrow edema imaging using a clinical CT system. Objectives were: (a) to quantitatively ...compare DECT with gold‐standard, fluid‐sensitive MRI for imaging of edema‐like marrow signal intensity (EMSI) and (b) to identify image analysis parameters that improve delineation of EMSI associated with acute knee injury on DECT images.
Methods
DECT images from ten participants with acute knee injury were decomposed into estimated fractions of bone, healthy marrow, and edema based on energy‐dependent differences in tissue attenuation. Fluid‐sensitive MR images were registered to DECT for quantitative, voxel‐by‐voxel comparison between the two modalities. An optimization scheme was developed to find attenuation coefficients for healthy marrow and edema that improved EMSI delineation, compared to MRI. DECT method accuracy was evaluated by measuring dice coefficients, mutual information, and normalized cross correlation between the DECT result and registered MRI.
Results
When applying the optimized three‐material decomposition method, dice coefficients for EMSI identified through DECT vs MRI were 0.32 at the tibia and 0.13 at the femur. Optimization of attenuation coefficients improved dice coefficient, mutual information, and cross‐correlation between DECT and gold‐standard MRI by 48%–107% compared to three‐material decomposition using non‐optimized parameters, and improved mutual information and cross‐correlation by 39%–58% compared to the manufacturer‐provided two‐material decomposition.
Conclusions
This study quantitatively evaluated the performance of DECT in imaging knee injury‐associated EMSI and identified a method to optimize DECT‐based visualization of complex tissues (marrow and edema) whose attenuation parameters cannot be easily characterized. Further studies are needed to improve DECT‐based EMSI imaging at the femur.
To prevent the progression of posttraumatic osteoarthritis, assessment of cartilage composition is critical for effective treatment planning. Posttraumatic changes include proteoglycan (PG) loss and ...elevated water content. Quantitative dual‐energy computed tomography (QDECT) provides a means to diagnose these changes. Here, we determine the potential of QDECT to evaluate tissue quality surrounding cartilage lesions in an equine model, hypothesizing that QDECT allows detection of posttraumatic degeneration by providing quantitative information on PG and water contents based on the partitions of cationic and nonionic agents in a contrast mixture. Posttraumatic osteoarthritic samples were obtained from a cartilage repair study in which full‐thickness chondral defects were created surgically in both stifles of seven Shetland ponies. Control samples were collected from three nonoperated ponies. The experimental (n = 14) and control samples (n = 6) were immersed in the contrast agent mixture and the distributions of the agents were determined at various diffusion time points. As a reference, equilibrium moduli, dynamic moduli, and PG content were measured. Significant differences (p < 0.05) in partitions between the experimental and control samples were demonstrated with cationic contrast agent at 30 min, 60 min, and 20 h, and with non‐ionic agent at 60 and 120 min. Significant Spearman's rank correlations were obtained at 20 and 24 h (ρ = 0.482–0.693) between the partition of cationic contrast agent, cartilage biomechanical properties, and PG content. QDECT enables evaluation of posttraumatic changes surrounding a lesion and quantification of PG content, thus advancing the diagnostics of the extent and severity of cartilage injuries.
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•Patients with gout have impaired muscle quality.•Patients with gout may be at increased risk of sarcopenia.•The importance of sarcopenia in rheumatic diseases is increasingly ...recognized.
Patients with gout are at elevated risk of multiple vascular and metabolic comorbidities. Whether they are also at risk of sarcopenia, which is known to affect patients with other rheumatic diseases, has not been previously assessed. We examined whether patients with gout have decreased lumbar muscle quality and quantity, indicating an association between gout and sarcopenia.
Fifty gout subjects and 25 controls, ages 45–80, underwent computed tomography imaging of the lumbosacral spine. We measured muscle quantity (skeletal muscle area SMA and index SMI) and quality (skeletal muscle radiation attenuation SMRA and intermuscular adipose tissue IMAT area and index IMATI) of the psoas and erector spinae muscles at the L3 level.
Seventy subjects (45 gout and 25 controls) were included in the analysis. Gout subjects had higher BMI, more kidney disease and hypertension, lower exercise frequency, and higher mean serum urate and creatinine vs. controls. Lumbar SMRA was significantly lower in gout subjects vs. controls, indicating reduced muscle quality. Lumbar IMAT area was significantly higher in gout subjects vs. controls, as was lumbar IMATI, indicating increased muscle adiposity. These differences persisted after adjusting for potential confounders. In contrast, there was no significant difference between gout and control groups in lumbar SMA or lumbar SMI, suggesting that muscle quantity may not be routinely affected by the diagnosis of gout.
Gout patients exhibit decreased lumbar muscle quality compared with controls, consistent with an association between gout and sarcopenia.
Objective
To evaluate clinical applications of dual‐energy computed tomography (DECT) in pediatric‐specific lung diseases and compare ventilation and perfusion findings with those from single‐photon ...emission computed tomography (SPECT‐CT) V/Q.
Methods
All patients at our institution who underwent exams using both techniques within a 3‐month period were included in this study. Two readers independently described findings for DECT, and two other readers independently analyzed the SPECT‐CT V/Q scan data. All findings were compared between readers and disagreements were reassessed and resolved by consensus. Inter‐modality agreements are described throughout this study.
Results
Eight patients were included for evaluation. The median age for DECT scanning was 3.5 months (IQR = 2). Five of these patients were scanned for both DECT and SPECT‐CT V/Q studies the same day, and three had a time gap of 7, 65, and 94 days between studies. The most common indications were chronic lung disease (5/8; 63%) and pulmonary hypertension (6/8; 75%). DECT and SPECT‐CT V/Q identified perfusion abnormalities in concordant lobes in most patients (7/8; 88%). In one case, atelectasis limited DECT perfusion assessment. Three patients ultimately underwent lobectomy with corresponding perfusion abnormalities identified by all reviewers on both DECT and SPECT‐CT V/Q in all resected lobes.
Conclusion
DECT is a feasible technique that could be considered as an alternative for SPECT‐CT V/Q for lung perfusion evaluation in infants.
To determine the dual-energy computed tomography (DECT) attenuation properties of meniscal calcifications in calcium pyrophosphate deposition (CPPD) in vivo, and assess whether DECT was able to ...discriminate meniscal CPP deposits from calcium hydroxyapatite (HA) in subchondral and trabecular bone.
Patients with clinical suspicion of crystal-related arthropathy (gout and/or CPPD) and knee DECT scans were retrospectively assigned to CPPD (n = 19) or control (n = 21) groups depending on the presence/absence of chondrocalcinosis on DECT. Two observers drew standardized regions of interest (ROI) in meniscal calcifications, non-calcified menisci, as well as subchondral and trabecular bone. Five DECT parameters were obtained: CT numbers (HU) at 80 and 140 kV, dual-energy index (DEI), electron density (ρe), and effective atomic number (Zeff). The four different knee structures were compared within/between patients and controls using linear mixed models, adjusting for confounders.
Meniscal calcifications (n = 89) in CPPD patients had mean ± SD CT numbers at 80 and 140 kV of 257 ± 64 and 201 ± 48 HU, respectively; with a DEI of 0.023 ± 0.007, and ρe and Zeff of 140 ± 35 and 8.8 ± 0.3, respectively. Meniscal CPP deposits were readily distinguished from calcium HA in subchondral and trabecular bone (p ≤ 0.001), except at 80 kV separately (p = 0.74). Zeff and ρe both significantly differed between CPP deposits and calcium HA in subchondral and trabecular bone (p < 0.0001).
This proof-of-concept study shows that DECT has the potential to discriminate meniscal CPP deposits from calcium HA in subchondral and trabecular bone in vivo, paving the way for the non-invasive biochemical signature assessment of intra- and juxta-articular calcium crystal deposits.
Gout is the most common cause of inflammatory arthritis in adults. Gout predominantly affects the peripheral joints, but an increasing number of published cases report gout affecting the spine. We ...used dual-energy CT (DECT) to assess the prevalence of monosodium urate (MSU) deposition in the spine of gout patients compared to controls, and to investigate whether gout or spinal MSU deposition is associated with low back pain.
25 controls and 50 gout subjects (non-tophaceous and tophaceous) were enrolled. Demographics, gout history, Aberdeen back pain score, serum urate (sU), ESR and CRP were ascertained. Subjects underwent DECT of the lumbosacral spine, which was analyzed using manufacturer's default post-processing algorithm for MSU deposition as well as a maximally-specific algorithm to exclude potential artifact.
72 subjects were analyzed (25 control, 47 gout). Gout subjects had greater BMI, serum creatinine, sU, CRP, and ESR versus controls. Using the default algorithm, MSU-coded volumes in the lumbosacral spines were significantly higher among the gout subjects vs controls (p = 0.018). 34% of gout subjects vs 4% of controls had spinal MSU-coded deposition (p = 0.0036). Applying the maximally-specific DECT post-processing algorithm, 18% of gout patients vs 0% of controls continued to demonstrate spinal MSU-coded deposition (p = 0.04). Non-tophaceous and tophaceous subjects did not differ in spinal MSU-coded deposition or sU. Gout patients had more back pain than controls.
A significant subpopulation of gout patients have spinal MSU-coded lesions. Default and maximally-specific MSU post-processing algorithms yielded different absolute MSU-coded volumes, but similar patterns of results. Gout patients had more back pain than controls. Spinal MSU deposition in gout patients may have implications for clinical picture and treatment.
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