Advanced Noise-Optimized Dual-Energy Virtual Monochromatic Imaging vs. Conventional 120-kVp CT Imaging: Image Quality Assessment

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 Methods: For 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. Results: The 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. Conclusion: Both 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.

Diagnostic Accuracy of 128-Slice Dual Source CT Coronary Angiography with Invasive Catheter Coronary Angiography in a Tertiary Care Teaching Hospital

Background: Coronary artery disease (CAD) morbidity and mortality increasing day by day in India as well as worldwide. Coronary arteries visualization by using invasive catheterization angiography is still using as a front-line diagnostic tool to evaluate the patients with CAD. 128 slice dual source CT improves the cardiac imaging such as high scanning speed, good temporal resolution and low radiation dose. Objective: To assess the diagnostic accuracy of 128-slice dual source CT cardiac angiography with conventional catheter angiography to find common arteries involved in CAD. Methods: This is a prospective, comparative, cross sectional study conducted at cardiology OPD. Patients with complaint of chest pain and suspected CAD were evaluated by CT and conventional coronary angiography and results were compared. Serum creatinine and ECG status were analyzed before the angiography. SIEMENS 128-slice Dual Source Flash Definition CT Scanner was used as a CT coronary angiography. Severity distribution of coronary artery disease, artery wise distribution of non-significant, significant lesions and coronary artery dominance pattern were analyzed and compared. Results: A total of 70 suspected CAD patients were selected and analyzed. American Heart Association (AHA) model of 17-segment was used to assess the coronary arteries. Normal angiograms reported in 15.71% patients and 58.57% had significant disease. A total of 356 lesions were identified from 690 out of 720 segments. Right coronary artery (RCA) is the most common location of significant lesions which contributes 33.5% (n=55/164). Coronary circulation of right-sided dominance was most commonly reported (70.0%). CT angiography showed 96.13% of an overall sensitivity, 96.28% specificity, 89.72% positive predictive value and 98.49% negative predictive value. Conclusion: 128-slice dual source CT scanner has showed high accuracy and act as non-invasive assessment of coronary arteries in patients with CAD Keywords: Cardiac angiography, Catheter coronary angiography, CT coronary angiography, 128-slice MDCT, Conventional angiography