Coronary computed tomography angiography (CCTA) is a first-line modality in the investigation of suspected coronary artery disease (CAD). Mapping of perivascular fat attenuation index (FAI) on routine CCTA enables the non-invasive detection of coronary artery inflammation by quantifying spatial changes in perivascular fat composition. We now report the performance of a new medical device, CaRi-Heart^®, which integrates standardized FAI mapping together with clinical risk factors and plaque metrics to provide individualized cardiovascular risk prediction. The study included 3912 consecutive patients undergoing CCTA as part of clinical care in the USA (n = 2040) and Europe (n = 1872). These cohorts were used to generate age-specific nomograms and percentile curves as reference maps for the standardized interpretation of FAI. The first output of CaRi-Heart^® is the FAI-Score of each coronary artery, which provides a measure of coronary inflammation adjusted for technical, biological, and anatomical characteristics. FAI-Score is then incorporated into a risk prediction algorithm together with clinical risk factors and CCTA-derived coronary plaque metrics to generate the CaRi-Heart^® Risk that predicts the likelihood of a fatal cardiac event at 8 years. CaRi-Heart^® Risk was trained in the US population and its performance was validated externally in the European population. It improved risk discrimination over a clinical risk factor-based model [Δ(C-statistic) of 0.085, P = 0.01 in the US Cohort and 0.149, P < 0.001 in the European cohort] and had a consistent net clinical benefit on decision curve analysis above a baseline traditional risk factor-based model across the spectrum of cardiac risk. Mapping of perivascular FAI on CCTA enables the non-invasive detection of coronary artery inflammation by quantifying spatial changes in perivascular fat composition. We now report the performance of a new medical device, CaRi-Heart^®, which allows standardized measurement of coronary inflammation by calculating the FAI-Score of each coronary artery. The CaRi-Heart^® device provides a reliable prediction of the patient's absolute risk for a fatal cardiac event by incorporating traditional cardiovascular risk factors along with comprehensive CCTA coronary plaque and perivascular adipose tissue phenotyping. This integration advances the prognostic utility of CCTA for individual patients and paves the way for its use as a dual diagnostic and prognostic tool among patients referred for CCTA.

Perivascular adipose tissue mapping by means of the coronary CT angiography (CCTA)–derived fat attenuation index is a recently developed method to noninvasively detect coronary inflammation and ath... Coronary CT angiography (CCTA) has evolved into a first-line diagnostic test for the investigation of chest pain. Despite advances toward standardizing the reporting of CCTA through the Coronary Ar...

Objectives: Photon-counting CT (PCCT) represents a newer CT technology with reduced electronic noise and potentially better dose efficiency than conventional CT. However, it remains unclear how vertical off-center positioning affects dose and image quality across a spectrum of patient sizes. The aim was to quantify the effects of vertical off-centering on radiation dose and image noise in PCCT using anthropomorphic phantoms representing both adult and pediatric body sizes. Materials and Methods: Three anthropomorphic phantoms (adult male, 10-year-old, and 5-year-old) were scanned on a commercially available PCCT system at multiple vertical offsets using a posteroanterior localizer with the x-ray tube positioned below the phantom. Chest and abdomen protocols were used, with radiation doses, Monte Carlo-simulated organ doses, and image noise recorded at each offset. Results: Off-centering markedly affected radiation dose, whereas image noise differed primarily between the predefined image quality levels. A strong linear relationship was observed between vertical offset and CTDI _vol [median R ² (IQL) = 0.85 (0.78-0.98)]. Downward off-centering (−4 cm) increased radiation dose by up to 16% in adults and 17% in pediatric phantoms for both chest and abdominal scans, with the largest effects in chest scans without tin filtration. Upward off-centering (+4 cm) reduced dose by up to 11% in adults and 8% in pediatric phantoms. Larger phantoms showed steeper regression slopes, indicating stronger dose dependence on positioning. In contrast, no consistent dependence of image noise on vertical off-centering was observed within a given image quality level [median R ² = 0.23 (0.03-0.52)]. Across all offsets, the overall variation reached +72%/-47% in chest PCCT and +66%/-13% in abdominal PCCT. Conclusions: Vertical off-center positioning substantially affects radiation dose in PCCT, whereas image noise appears largely independent of vertical positioning within a given image quality level. Meticulous isocenter alignment remains crucial for both adult and pediatric imaging to avoid unnecessary radiation and sustain diagnostic image quality.

Photon-counting computed tomography (PCCT) offers new possibilities for optimizing image quality while reducing radiation dose. However, the influence of acquisition parameters such as tube voltage and spectral shaping with tin filtration on chest imaging remains insufficiently understood. Adult male and female anthropomorphic phantoms were scanned using a dual-source PCCT system across a broad range of image quality levels (IQL 1–100). Radiation dose and signal-to-noise ratio (SNR) were evaluated for protocols using 120 kVp and 140 kVp without tin filtration, and 100 kVp with tin filtration. The male phantom required a significantly higher tube current and radiation dose than the female, reflecting sex-based attenuation differences. Increasing the tube voltage to 140 kVp raised the radiation dose with minimal SNR improvement. Tin filtration substantially reduced the dose despite a higher mAs, with the radiation dose and tube current plateauing near IQL 80. In the low-dose range (IQL 1–20), tin filtration enabled dose reduction without saturation. Slight SNR trade-offs between bone and mediastinum highlight the need for tissue-specific considerations when optimizing PCCT chest protocols. Sex- and tissue-specific differences with tin filtration and varying tube voltages underscore baseline differences in radiation dose and image quality behavior between representative adult body geometries. These baseline relationships provide a technical foundation for future patient-specific protocol optimization.

Purpose: The aim of the study was to investigate whether the ventriculoperitoneal (VP) shunt valve setting can be reliably assessed using maximum intensity projection (MIP) reconstructions from non-contrast, full-dose head CT scans, and how this method performs in comparison to conventional lateral skull radiographs. Methods: This retrospective study included 41 adult patients (mean age 59 ± 25 years) with Codman Certas programmable VP shunt valves who underwent lateral skull X‑ray and a same-day, non-contrast head CT scan between January and July 2024. From the CT data, MIP reconstructions of the valve region were generated. Three neuroradiologists, blinded to each other’s assessments, independently rated valve settings and image quality using a 5-point Likert scale. Mean reconstruction time was recorded. Radiation dose data were extracted from institutional dose-monitoring software. Results: Valve settings were identifiable in all 44 CT/X-ray image pairs, with 95% agreement between MIP and X-ray readings. MIP reconstructions were successfully generated (median CTDI _vol 35.34 mGy (30.42; 40.32); mean reconstruction time 70 s). Image quality was rated lower for MIP (median 2 [IQR 2]) than for X‑ray (median 4 [IQR 1]; p < 0.001). In 45% of cases scanned with photon-counting CT, MIP quality was significantly higher (median 3 vs. 1; p < 0.001). Inter-reader reliability was good for MIPs (ICC = 0.82) and excellent for X‑rays (ICC = 0.97). Conclusion: MIP reconstructions from non-contrast head CT allow reliable VP shunt valve setting assessment and may reduce the need for additional radiographs, especially when advanced CT systems are used.

Purpose: The standard modality for the diagnosis of ventriculoperitoneal (VP) shunt failure is the radiographic shunt series (RSS). However, ultra-low dose computed tomography (ULD-CT) may replace RSS. The aim of this study was to compare the radiation doses of RSS and ULD-CT in the diagnosis of mechanical shunt failure in human phantoms including pediatric phantoms and to further reduce the total CT dose by reducing the topogram radiation. Methods: Mechanical VP shunt complications were placed on human phantoms representing ages of 1, 5, 10 and 30 years. RSS and ULD-CT were performed on each phantom with different radiation doses of the topogram with varying tube currents (10, 20, 30, 40 and 50 mAs). Effective doses of RSS and ULD-CT were estimated by using conversion factors. Results: ULD-CT demonstrated lower effective doses than RSS in phantoms representing ages 5, 10 and 30 years, while successfully depicting all mechanical shunt complications. However, higher effective doses were assessed for ULD-CT scans of the 1-year phantom than RSS. The effective doses for RSS and ULD-CT (utilizing 10 mAs topograms), respectively, were estimated as follows: 1-year: 0.056 vs. 0.133 mSv; 5-year: 0.186 vs. 0.123 mSv; 10-year: 0.240 vs. 0.107 mSv; 30-year: 0.641 vs. 0.076 mSv. Conclusion: This study demonstrated ULD-CT as an alternative to RSS for the detection of mechanical VP shunt complications, reducing radiation doses in phantoms equivalent to 5 years of age and older while demonstrating the complications equally to RSS. This may be of clinical interest, especially in children due to the reduction of radiation risks.