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Objective This study aims to determine if low iodine dynamic computed tomography angiography performed after a fixed delay or test bolus acquisition demonstrates high concordance with clinical computed tomography angiography (using a routine amount of iodinated contrast) to display lower extremity peripheral arterial disease. Methods After informed consent, low iodine dynamic computed tomography angiography examination (using either a fixed delay or test bolus) using 50 ml of iodine contrast media was performed. A subsequent clinical computed tomography angiography using standard iodine dose (115 or 145 ml) served as the reference standard. A vascular radiologist reviewed dynamic and clinical computed tomography angiography images to categorize the lumen into “not opacified”, “70% stenosis”, and “occluded” for seven arterial segments in each lower extremity. Concordance between low iodine dynamic computed tomography angiography and the routine iodine reference standard was calculated. The clinical utility of 4D volume-rendered images was also evaluated. Results Sixty-eight patients (average age 66.1 ± 12.3 years, male; female = 49: 19) were enrolled, with 34 patients each undergoing low iodine dynamic computed tomography angiography using fixed delay and test bolus techniques, respectively. One patient assigned to the test bolus group did not undergo low iodine computed tomography angiography due to unavailable delayed time. The fixed delay was 13 s, with test bolus acquisition resulting in a mean variable delay prior to image acquisition of 19.5 s (range; 8–32 s). Run-off to the ankle was observed using low iodine dynamic computed tomography angiography following fixed delay and test bolus acquisition in 76.4% (26/34) and 100% (33/33) of patients, respectively ( p = 0.005). Considering extremities with run-off to the ankle and without severe artifact, the concordance rate between low iodine dynamic computed tomography angiography and the routine iodine reference standard was 86.8% (310/357) using fixed delay and 97.9% (425/434) using test bolus ( p Conclusion Low iodine dynamic computed tomography angiography with test bolus acquisition has a high concordance with routine peripheral computed tomography angiography performed with standard iodine dose, resulting in improved run-off to the ankle compared to dynamic computed tomography angiography performed after a fixed delay. This method is useful for minimizing iodine dose in patients at risk for contrast-induced nephropathy. 4D volume-rendered computed tomography angiography images provide useful dynamic information.

To obtain 3D CT measurements of mitral annulus throughout cardiac cycle using prototype mitral modeling software, assess interobserver agreement, and compare among patients with mitral prolapse (MP) and control group.Pre-procedural imaging is critical for planning of transcatheter mitral valve (MV) replacement. However, there is limited data regarding reliable CT-based measurements to accurately characterize the dynamic geometry of the mitral annulus in patients with MV disease.Patients with MP and control subjects without any MV disease who underwent ECG-gated cardiac CT were retrospectively identified. Multiphasic CT data was loaded into a prototype mitral modeling software. Multiple anatomical parameters in 3D space were recorded throughout the cardiac cycle (0-95%): annular circumference, planar-surface-area (PSA), anterior-posterior (A-P) distance, and anterolateral-posteromedial (AL-PM) distance. Comparisons were made among the two groups, with p 0.05 considered statistically significant. Interobserver agreement was assessed on ten patients using intraclass correlation coefficient (ICC) among 4 experienced readers.A total of 100 subjects were included: 50 with MP and 50 control. Annular dimensions were significantly higher in the MP group than control group, with circumference (144 ± 11 vs. 117±8 mm), PSA (1533 ± 247 vs. 1005 ± 142 mmA significant variation in the mitral annular measures between different cardiac phases and two groups was observed with excellent interobserver agreement.

Background Low tube potential-high tube current computed tomography (CT) imaging allows reduction in iodine-based contrast dose and may extend the benefit of routine contrast-enhanced CT exams to patients at risk of nephrotoxicity. Purpose To determine the ability of an iodine contrast reduction algorithm to maintain diagnostic image quality for contrast-enhanced abdominal CT. Material and Methods CT exams with iodine contrast reduction were prescribed for patients at risk for renal dysfunction. The iodine contrast reduction algorithm combines weight-based contrast volume reduction with patient width-based low tube potential selection and bolus-tracking. Control exams with routine iodine dose were selected based on weight, width, and scan protocol. Three radiologists evaluated image quality and diagnostic confidence using a 4-point scale (Results Forty-six contrast reduction algorithm and control exams were compared (mean creatinine 1.6 vs. 1.2 mg/dL, P ≤ 0.0001). Thirty-nine contrast reduction patients had an eGFR 2 and 15 had single or transplanted kidney. Mean iodine contrast dose was lower in the contrast reduction group (20.9 vs. 39.4 g/mL, P < 0.0001). Diagnostic confidence was rated as acceptable in 95% (131/138) of contrast reduction and 100% of control exams (1.18–1.28 vs. 1.02–1.13, respectively; P > 0.06). Liver attenuation and contrast-to-noise ratio (CNR) were similar ( P = 0.08), but portal vein attenuation and CNR were lower with contrast-reduction (mean 176 vs. 198 HU, P = 0.02; 13 vs. 16, P = 0.0002). Conclusion This size-based contrast reduction algorithm using low kV and bolus tracking reduced iodine contrast dose by 50%, while achieving acceptable image quality in 95% of exams.

Objective Chest computed tomography (CT) imaging enables detailed visualization of the pulmonary structures and diseases. This article reviews how continued innovation and improvements in modern CT system hardware and software now facilitate a wider range of image acquisition options and generate unique qualitative and quantitative information that can benefit patients Results Dual energy imaging utilizes two x-ray energies to highlight differences in tissue properties and increase iodine signal to improve diagnosis or reduce metal artifacts. Ultra-low dose imaging can be performed by using additional x-ray beam filtration, such as a tin filter, combined with iterative reconstruction algorithms to benefit lung cancer screening or pediatric imaging. Ultra-fast pitch spiral acquisition improves temporal resolution and reduces motion artifacts. Higher spatial resolution acquisition and reconstruction methods permit improved visualization of small structures. Radiomic analysis of chest CT image features permits risk stratification of pulmonary nodules and masses and reliable measures of change in pulmonary architecture and disease. Conclusions Multiple new CT acquisition and reconstruction techniques, along with advanced post processing methods permit detailed analysis of changes in pulmonary architecture and function, and an expanded ability to adapt chest CT to the unique needs of different patients.

OBJECTIVE The aim of this study was to determine if computed tomography (CT) angiography using an individualized transition delay (CTA-ID) would facilitate reductions in injection rate and iodine dose. METHODS The CTA-ID was performed in 20 patients with routine injection rate and iodine dose; 20 patients with injection rate lowered by 1 mL/s; and 40 patients with injection rate lowered by 1 mL/s with 29% less iodine. Routine CTAs in the same or size-matched patients served as controls. Diagnostic image quality and intra-arterial CT numbers were assessed. RESULTS The median transition delay between aortic threshold and CTA-ID image acquisition was significantly longer than with conventional bolus tracking (mean increase, 13.3 seconds; P < 0.0001), with image quality being the same or better. Intra-arterial CT numbers were 200 Hounsfield units or greater for 80 of 80 CTA-ID, but not for 6 of 49 (12%) internal control or for 11 of 80 (14%) size-matched control patients. CONCLUSION The CTA-ID bolus-tracking software alters transition delays to permit diagnostic CTA examinations despite slower injection rate and less iodine.

PURPOSE: To determine the accuracy of CT number and calcium score of a kV-independent technique based on an artificial 120 kV reconstruction, and its potential to reduce radiation dose. METHODS: Anthropomorphic chest phantoms were scanned on a third-generation dual-source CT system equipped with the artificial 120 kV reconstruction. First, a phantom module containing a 20-mm diameter hydroxyapatite (HA) insert was scanned inside the chest phantoms at different tube potentials (70–140 kV) to evaluate calcium CT number accuracy. Next, three small HA inserts (diameter/length = 5 mm) were inserted into a pork steak and scanned inside the phantoms to evaluate calcium score accuracy at different kVs. Finally, the same setup was scanned using automatic exposure control (AEC) at 120 kV, and then with automatic kV selection (auto-kV). Phantoms were also scanned at 120 kV using a size-dependent mA chart. CT numbers of soft tissue and calcium were measured from different kV images. Calcium score of each small HA insert was measured using commercial software. RESULTS: The CT number difference from 120 kV was small with tube potentials from 90 to 140 kV for both soft tissue and calcium (maximal difference of 4/5 HU, respectively). Consistent calcium scores were obtained from images of different kVs compared to 120 kV, with a relative difference

Continued advances in computed tomographic angiography (CTA) over the years have facilitated an increasing role of CTA in evaluating the arteries of the upper and lower extremities. Current applications of peripheral arterial CTA include arterial occlusive disease, aneurysmal disease, trauma, vasculitis, arteriovenous fistulae and malformations, vascular compression and entrapment syndromes, and surgical planning (Cook 2016; Dave and Fleischmann 2016).