Prototype Ultrahigh-Resolution Computed Tomography for Chest Imaging: Initial Human Experience.

OBJECTIVE: The objective of this study was to evaluate a prototype, ultrahigh-resolution computed tomography offering higher reconstruction matrix (1024 × 1024) and spatial resolution (0.15 mm) for chest imaging. METHODS: Higher (1024) matrix reconstruction enabled by ultrahigh-resolution computed tomography scanner (128-detector rows; detector width, 0.25 mm; spatial resolution, 0.15 mm) was compared with conventional (512) reconstruction with image quality grading on a Likert scale (1, excellent; 5, nondiagnostic) for image noise, artifacts, contrast, small detail, lesion conspicuity, image sharpness, and diagnostic confidence. Image noise and signal-to-noise ratio were quantified. RESULTS: Diagnostic image quality was achieved for all scans on 101 patients. The 1024 reconstruction demonstrated increased image noise (20.2 ± 4.0 vs 17.2 ± 3.8, P < 0.001) and a worse noise rating (1.98 ± 0.63 vs 1.75 ± 0.61, P < 0.001) but performed significantly better than conventional 512 matrix with fewer artifacts (1.37 ± 0.43 vs 1.50 ± 0.48, P < 0.001), better contrast (1.50 ± 0.56 vs 1.62 ± 0.57, P < 0.001), small detail detection (1.06 ± 0.19 vs 2.02 ± 0.22, P < 0.001), lesion conspicuity (1.08 ± 0.23 vs 2.02 ± 0.24, P < 0.001), sharpness (1.09 ± 0.24 vs 2.02 ± 0.28, P < 0.001), and overall diagnostic confidence (1.09 ± 0.25 vs 1.18 ± 0.34, P < 0.001). CONCLUSIONS: Ultrahigh-resolution computed tomography enabled a higher reconstruction matrix and improved image quality compared with conventional matrix reconstruction, with a minor increase in noise.

Reduced radiation dose with model based iterative reconstruction coronary artery calcium scoring.

Assessing coronary artery calcium (CAC) is a valuable tool for individualizing cardiac risk assessment. In CAC scanning, this technical report assesses the use of a true model-based iterative reconstruction algorithm using forward projected model-based iterative reconstruction ("FIRST") and assess whether FIRST allows for reduced radiation dose CAC scanning on 320-detector row computed tomography (320-CT). Here, 100 consecutive patients prospectively underwent reduced and standard dose scans. For the patients (59 ± 9 years, 61% male) stratified by Agatston categories 0, 1-10, 11-100, 101-400,> 400, agreement between reduced dose with FIRST versus standard dose with FBP was excellent at 81% (95% CI: 73-88%) with kappa 0.74 (95% CI: 0.64-0.85). Median radiation exposure was 75% lower for reduced (0.35 mSv) versus standard dose (1.37 mSv) scans. In conclusion, agreement was excellent for reduced dose with FIRST and standard dose with FBP in 320-detector row CT CAC imaging in well-established categories of cardiovascular risk. These methods make it possible to reduce radiation exposure by 75%.

Feasibility of low radiation dose retrospectively-gated cardiac CT for functional analysis in adult congenital heart disease.

BACKGROUND: The use of cardiac computed tomography (CT) in the evaluation of adult congenital heart disease patients is limited due to concerns of high radiation doses. The purpose of this study was to prospectively assess whether low radiation dose cardiac CT is feasible to evaluate ventricular systolic function in adults with congenital heart disease. METHODS: The study group included 30 consecutive patients with significant congenital heart disease who underwent a total of 35 ECG-gated cardiac CT scans utilizing a 320-detector row CT scanner. Each study included a non-contrast scan and subsequent contrast-enhanced retrospectively-gated acquisition. Effective radiation dose was estimated by multiplying the dose length product by a k-factor of 0.014mSv/mGycm. RESULTS: The mean age of the patients was 34.4±8.9years, 60% were men, and mean body mass index was 24.2±4.3kg/m2. A majority of patients (n=28, 93.3%) had contraindications to cardiac MRI. A tube potential of 80kV was used in 27 (77.1%) of the contrast-enhanced scans. The mean signal-to-noise and contrast-to-noise ratios were 11.5±3.9 and 10.3±3.7, respectively. The median radiation dose for non-contrast and contrast-enhanced images were 0.1mSv (0.07-0.2mSv) and 0.94mSv (0.5-2.1mSv), respectively. All 35 CT scans were successfully analyzed for ventricular systolic function. CONCLUSIONS: A low radiation contrast-enhanced, retrospectively-gated cardiac CT with a median radiation dose of less than 1mSv was successful in evaluating ventricular systolic function in 30 consecutive adult congenital heart disease patients who underwent a total of 35 scans.