Neurovascular Imaging with Ultra-High-Resolution Photon-Counting CT: Preliminary Findings on Image Quality Evaluation.

BACKGROUND AND PURPOSE: The first-generation photon-counting detector (PCD) CT was recently introduced into clinical practice and represents a promising innovation in high-resolution CT imaging. The purpose of this study was to assess the image quality of ultra-high-resolution (UHR) PCD-CT compared with energy-integrating detector (EID)-CT, and to explore different reconstruction kernel sharpness levels for the evaluation of intracranial aneurysms. MATERIALS AND METHODS: Ten patients with intracranial saccular aneurysms, who had previously undergone conventional EID-CT, were prospectively enrolled. CT angiograms were acquired on a clinical dual-source PCD-CT in UHR mode, and reconstructed with four vascular kernels (Bv36, Bv40, Bv44, Bv48). Quantitative and qualitative image quality parameters of the intracranial arteries were evaluated. For the quantitative analysis (image noise, SNR, CNR), regions of interest were manually placed at standard anatomical intracranial and extracranial locations by one author. In addition, vessel border sharpness was evaluated quantitatively. For the qualitative analysis, three blinded neuroradiologists rated PCD-CT and EID-CT image quality for the evaluation of the intracranial vessels (i.e., the aneurysms and nine standard vascular branching locations) on a 5-point Likert-type scale. Additionally, readers independently selected their preferred kernel among the four kernels evaluated on PCD-CT. RESULTS: In terms of quantitative image quality, Bv48, the sharpest kernel, yielded increased image noise, and decreased SNR and CNR parameters compared to Bv36, the smoothest kernel. Compared to EID-CT, the Bv48 kernel offered better quantitative image quality for the evaluation of small intracranial vessels (p < .001). Image quality ratings of the Bv48 were superior to those of the EIDCT, and not significantly different from ratings of the B44 reconstruction kernel. When comparing side-by-side all four PCD-CT reconstruction kernels, readers selected the B48 kernel as the best to visualize the aneurysms in 80% of cases. CONCLUSIONS: UHR PCD-CT provides improved image quality for neurovascular imaging. Although the less sharp kernels provided superior SNR and CNR, the sharpest kernels delivered the best subjective image quality on PCD-CT for the evaluation of intracranial aneurysms.CNR ＝ Contrast-to-Noise Ratio; EID-CT ＝ Energy-Integrating Detector CT; PCD-CT ＝ Photon-Counting Detector CT; QIR ＝ Quantum Iterative Reconstruction; UHR ＝ Ultra-High-Resolution.

Non-sedated fast spine magnetic resonance imaging in pediatric patients.

BACKGROUND: Traditional spine magnetic resonance imaging (MRI) protocols require sedation in young children and uncooperative patients. There is an increased interest in non-sedated pediatric MRI protocols to reduce risks associated with anesthetic agents and improve MRI access. OBJECTIVE: To evaluate the image quality of pediatric non-sedated fast spine MRI. MATERIALS AND METHODS: We retrospectively reviewed 69 pediatric non-sedated fast spine MRI exams performed in 57 patients. Two blinded readers provided image quality ratings for the evaluation of bones, cranio-cervical junction, cerebrospinal fluid (CSF) spaces, spinal cord, soft tissues, ligaments, and overall diagnostic quality on a 1-5 scale, and determined whether there was evidence of syringomyelia, abnormal conus medullaris position, or filum terminale abnormality. RESULTS: Mean patient age was 7.2 years (age range ≤ 1-17). Indications included syringomyelia (n=25), spinal dysraphism (n=4), combination of both syringomyelia and spinal dysraphism (n=8), and other miscellaneous indications (n=32). The inter-observer agreement ranged between moderate and very good for each variable (Cohen's weighted kappa] range=0.45-0.69). The highest image quality ratings were given to CSF spaces (mean image quality=3.5/5 ± 0.8) and cranio-cervical junction evaluations (3.5/5 ± 0.9). Overall diagnostic quality was worst in the <5 years group (P=0.006). Readers independently identified a cervical spinal cord syrinx in 6 cases, and 1 mm spinal cord central canal dilation in one case. Readers agreed on the position of the conus medullaris in 92% of cases (23/25 cases). CONCLUSION: Non-sedated pediatric spine MRI can be an effective diagnostic test to evaluate for spine pathology, especially syringomyelia, Chiari malformation, and conus medullaris anatomy.

Impact of Delayed Time to Antibiotics in Medical and Surgical Necrotizing Enterocolitis.

This study investigated whether delayed receipt of antibiotics in infants with necrotizing enterocolitis (NEC) is associated with disease severity. In this retrospective, single-center cohort study of infants diagnosed with NEC over 4 years, we compared the timing of antibiotic administration in infants (time order placed to time of receipt) in medical and surgical NEC. Cases were independently reviewed, then various clinical factors were compared. Of 46 suspected cases, 25 were confirmed by a panel of radiologists with good interrater reliability (ICC 0.657; p < 0.001). Delays in antibiotic receipt were 1.7× greater in surgical than medical NEC cases (p = 0.049). Every hour after order entry increased the adjusted odds of surgical NEC by 2.4 (1.08−5.23; p = 0.032). Delayed antibiotic receipt was more common in infants with surgical than medical NEC. Larger studies will be needed to investigate if optimizing antibiotic expediency could improve intestinal outcomes.

Evaluation of liver fibrosis and hepatic venous pressure gradient with MR elastography in a novel swine model of cirrhosis.

PURPOSE: To assess the correlation among MR elastography (MRE) measured liver stiffness (LS), liver fibrosis, and hepatic venous pressure gradient (HVPG) in a swine model of cirrhosis. MATERIALS AND METHODS: Three swine served as controls, and liver fibrosis was induced in eight swine by transarterial embolization. LS and HVPG were obtained at baseline and 4 weeks (prenecropsy) following induction of liver fibrosis. RESULTS: Four weeks following the induction of liver cirrhosis, experimental animals developed an increase in HVPG of 8.0±6.4 mmHg compared with 0.3±1.2 mmHg for controls (P=0.08). Over the same timeframe, mean MRE-measured LS increased 0.82±0.39 kPa for experimental swine and 0.1±0.05 kPa for controls (P=0.01). A positive correlation was observed between increases in HVPG and LS (ρ=0.682; P=0.02). Liver fibrosis was measured on explanted livers at 4 weeks and yielded mean fibrosis scores of 2.8 for experimental animals and 0 for controls (P=0.0016). A positive correlation was observed between higher LS and liver fibrosis (ρ=0.884; P=0.0003). CONCLUSION: MRE is a reliable noninvasive technique to measure LS in a swine model of cirrhosis. Significant positive correlations were observed between LS and HVPG as well as LS and fibrosis.