dual energy computed tomography
در نشریات گروه پزشکی-
Background
The spatial pattern of monosodium urate (MSU) crystal deposition is a hallmark of gout progression and contributes to the pathogenesis of associated comorbidities. However, the correlations between MSU crystal volume in the feet/ankle, knee, and hand/wrist joint sites and clinical features in gout patients remain unclear.
ObjectivesThis study aims to explore the spatial pattern of MSU crystal deposition and its potential relationship with associated comorbidities. Additionally, it evaluates the correlation between MSU crystal volume detected by dual-energy computed tomography (DECT) in different joints and clinical characteristics, including serum uric acid (sUA), glomerular filtration rate (GFR), and disease duration. Patients and
MethodsIn this single-center study conducted from October 2017 to August 2023, 527 patients (mean age 49.0 ± 23.0 years) diagnosed with gout and confirmed MSU deposition via DECT were included. Spearman's rank correlation coefficient was used to assess relationships between sUA, gout duration, GFR, and MSU volumes in the foot/ankle, knee, and hand/wrist.
ResultsAmong the 527 patients, the median gout duration was 6.0 years. MSU crystals were most commonly found in the feet/ankles (84.8%), followed by knees (63.6%) and hands/wrists (28.8%). Gout duration positively correlated with MSU crystal volumes (r = 0.32, P < 0.01). MSU volumes in the feet/ankle and knee showed negative correlations with GFR (r = -0.18, P < 0.01; r = -0.16, P = 0.03, respectively), while no significant correlation was observed in hand/wrist volume (r = -0.06, P = 0.55). No significant associations were found between MSU volumes and sUA levels across all groups.
ConclusionThe MSU crystal burden negatively correlates with GFR but not with sUA levels. The volumes of MSU crystals in the ankle/foot and knee joints, along with the total volume of MSU crystals in the ankle/foot, hands/wrists, and knee joints, show a negative correlation with GFR and a positive correlation with disease duration. This indicates a need for further research on the relationship between MSU deposition and renal dysfunction in gout patients.
Keywords: Crystal Arthropathy, Gout, Dual-Energy Computed Tomography, Monosodium Urate -
Purpose
This study aimed at evaluating the image quality characteristics of advanced noise-optimized and traditional virtual monochromatic images compared with conventional 120-kVp images from second-generation Dual-Source CT.
Materials and MethodsFor spiral scans six syringes filled with diluted iodine contrast material (1, 2, 5, 10, 15, 20 mg I/ml) were inserted into the test phantom and scanned with a second-generation dual-source CT in both single-energy (120-kVp) and dual-energy modes. Images set contain conventional single-energy 120-kVp, and virtual monochromatic were reconstructed with energies ranging from 40 to 190-keV in 1-keV steps. An energy-domain noise reduction algorithm was applied and the mean CT number, image noise, and iodine CNR were calculated.
ResultsThe iodine CT number of conventional 120-kVp images compared with monochromatic of 40-, 50-, 60- and 70-keV images showed increase. The improvement ratio of image noise on Advanced Virtual Monochromatic Images (AVMIs) compared with the Traditional Virtual Monochromatic Images (TVMIs) at energies of 40-, 50-, 60, 70-keV was 52.9%, 35.7%, 8.1%, 2.1%, respectively. At AVMIs from 75- to 190-keV, the image noise value was less than conventional 120-kVp images. CNR improvement ratio at 20 mg/ml of iodinated contrast material for TVMIs and AVMIs compared to 120-kVp CT images and AVMIs compared to TVMI was 18.3% and 56.3%, 32.1% respectively.
ConclusionBoth TVMIs (in energies ranging from 54 to 71-keV) and AVMIs (in energies ranging from 40 to 74-keV) represent improvement in the iodine contrast-to-noise ratio than conventional 120-kVp CT images for the same radiation dose. Also, AVMIs compared to TVMIs have been obtained considerable noise reduction and CNR improvement for low-energy virtual monochromatic images. In the present study, we show that virtual monochromatic image and its Advanced version (AVMI) may boost the dual-energy CT advantages by providing higher CNR images in the same exposure value compared to routinely acquired single-energy CT images.
Keywords: Dual-Source Computed Tomography, Dual Energy Computed Tomography, Advanced VirtualMonochromatic Images, Traditional Virtual Monochromatic Images, Contrast-to-Noise Ratio -
Background
Multidetector computed tomography (MDCT) angiography is considered as the gold standard imaging modality in the evaluation of acute pulmonary embolism. Optimum vascular enhancement is critical for MDCT studies. The suboptimal opacification in pulmonary artery could be salvaged using low-energy virtual monoenergetic images (VMI) at rapid kVP switch dual energy CT.
ObjectivesTo explore the potential improvement in pulmonary artery opacification and to assess the change in image quality parameters in VMI using fast switch kVp dual energy CT. Patients and
MethodsThe CT images of 877 patients who were referred with a preliminary diagnosis of pulmonary embolism were reviewed. Sixty patients with suboptimal enhancement (< 200 Hounsfeld Unit [HU]) were involved. Standard images (140 kVp) and VMI from 40 to 120 keV were generated. Attenuation, noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were measured in the pulmonary artery. Using VMIs, the best image was determined as the image with the main pulmonary artery opacification greater than 200 HU and image quality ≥ 3. Fifty six studies that met these criteria were considered as salvaged. At this best energy level, quantitative parameters were compared with standard images.
ResultsThe mean attenuation of pulmonary arteries was 169.80 HU in standard images in patients with suboptimal enhancement. The attenuations of VMIs at 40, 45, 50, 55, 60, 65, and 70 keV were significantly higher than standard images (P < 0.001). Similar findings were observed with SNR and CNR. In the salvaged patients, the average increase in mean pulmonary artery attenuation was 62% (from 172.61 ± 23.4 to 280.55 ± 40.7), the average increase in SNR was 38% (from 12.1 ± 5.3 to 16.7 ± 7.1) and the average increase in CNR was 48% (9.2 ± 4.3 to 13.7 ± 6) (P < 0.001).
ConclusionsLow keV VMI reconstructions significantly increase pulmonary artery attenuation, CNR and SNR compared to standard image reconstructions. Suboptimal CT studies could be salvaged using low keV VMIs.
Keywords: Dual Energy Computed Tomography, Pulmonary Artery, Pulmonary Embolism
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