Evaluation of ECG-Gated, High-Pitch Thoracoabdominal Angiographies With Dual-Source Photon-Counting Detector Computed Tomography.

PURPOSE: The aim of this study was to evaluate the radiation dose, image quality, and the potential of virtual monoenergetic imaging (VMI) reconstructions of high-pitch computed tomography angiography (CTA) of the thoracoabdominal aorta on a dual-source photon-counting detector-CT (PCD-CT) in comparison with an energy-integrating detector-CT (EID-CT), with a special focus on low-contrast attenuation. METHODS: Consecutive patients being referred for an electrocardiogram (ECG)-gated, high-pitch CTA of the thoracoabdominal aorta prior to transcatheter aortic valve replacement (TAVR), and examined on the PCD-CT, were included in this prospective single-center study. For comparison, a retrospective patient group with ECG-gated, high-pitch CTA examinations of the thoracoabdominal aorta on EID-CT with a comparable scan protocol was matched for gender, body mass index, height, and age. Virtual monoenergetic imaging reconstructions from 40 to 120 keV were performed. Enhancement and noise were measured in 7 vascular segments and the surrounding air as mean and standard deviation of CT values. The radiation dose was noted and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Finally, a subgroup analysis was performed, comparing VMI reconstructions from 40 keV to 70 keV in patients with at least a 50% decrease in contrast attenuation between the ascending aorta and femoral arteries. RESULTS: Fifty patients (mean age 77.0±14.5 years; 31 women) were included. The radiation dose was significantly lower on the PCD-CT (4.2±1.4 vs. 7.2±2.2 mGy; p<0.001). With increasing keV, vascular noise, SNR, and CNR decreased. Intravascular attenuation was significantly higher on VMI at levels from 40 to 65, compared with levels of 120 keV (p<0.01 and p<0.005, respectively). On the PCD-CT, SNR was significantly higher in keV levels 40 and 70 (all p<0.001), and CNR was higher at keV levels 40 and 45 (each p<0.001), compared with scans on the EID-CT. At VMI ≤60 keV, image noise was also significantly higher than that in the control group. The subgroup analysis showed a drastically improved diagnostic performance of the low-keV images in patients with low-contrast attenuation. CONCLUSION: The ECG-gated CTA of the thoracoabdominal aorta in high-pitch mode on PCD-CT have significantly lower radiation dose and higher objective image quality than EID-CT. In addition, low-keV VMI can salvage suboptimal contrast studies, further reducing radiation dose by eliminating the need for repeat scans. CLINICAL IMPACT: ECG-gated CT-angiographies of the thoracoabdominal aorta can be acquired with a lower radtiation dose and a better image quality by using a dual-source photon-countinge detector CT. Furthermore, the inherent spectral data offers the possiblity to improve undiagnostic images and thus saves the patient from further radiation and contrast application.

[Radiological imaging to assess individual cardiovascular risk]. / Radiologische Bildgebung zur Bestimmung des individuellen kardiovaskulären Risikos.

CLINICAL/METHODICAL ISSUE: Radiologic imaging for the assessment of individual cardiovascular risk. STANDARD RADIOLOGICAL METHODS: The correct estimation of the individual cardiovascular risk is prerequisite for the prevention of cardiovascular diseases. Here, extensive evidence is available for coronary calcium scans as well as coronary CT angiography (CTA). METHODICAL INNOVATIONS: Summary of the available evidence for the use of calcium score and coronary CTA. Illustration of the significance of both tests in current guidelines. PERFORMANCE: Both tests have high prognostic value, surpassing a risk-factor based assessment. In comparison with the calcium score, the CTA has higher incremental value. ACHIEVEMENTS: Results from recent trials confirm an improvement of outcomes in symptomatic patients by performing a CTA compared with standard care. PRACTICAL RECOMMENDATIONS: European and US guidelines recommend a calcium score for risk stratification of asymptomatic patients with a low to intermediate risk profile. For symptomatic patients with low to intermediate coronary artery disease pretest probability, a CTA is recommended.

Evaluation of run-off computed tomography angiography on a first-generation photon-counting detector CT scanner - Comparison with low-kVp energy-integrating CT.

PURPOSE: To assess the overall imaging performance (radiation dose and image quality) of a photon-counting detector CT (PCD-CT) in comparison with a state-of-the-art energy-integrating detector CT (EID-CT) in run-off CTAs. METHODS: Consecutive patients who underwent run-off CTA on a PCD-CT were included (PCD-CT cohort). A retrospective cohort of patients who had undergone run-off CTA on an EID-CT was matched for gender, body mass index, height, and age (EID-CT cohort). Virtual monoenergetic imaging (VMI) reconstructions for various keV settings (40-120 keV) were generated. CT values and noise were semiautomatically measured for 13 vascular segments of the abdomen, pelvis, and lower extremities. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for each segment. Subjective image quality was evaluated by two radiologists along the dimensions 'vessel attenuation', 'vessel sharpness', and 'overall image quality' using 5-point Likert scales. RESULTS: Forty patients (age 70.9 ± 9.8 years; 14 women) were included in the PCD-CT cohort and matched with a corresponding number of EID-CT patients. Overall, there was an inverse correlation of signal and noise but also of SNR and CNR with keV levels used for VMI reconstructions. SNR and CNR in the 40 - 60 keV range exceeded EID-CT levels significantly. Subjective image quality was substantially higher at lower keV levels and showed no significant difference to EID-CT. CONCLUSION: Low keV VMI reconstructions of run-off CTA scans on a PCD-CT result in substantially higher SNR and CNR than 80 kVp and 100 kVp EID-CT acquisitions with equal subjective image quality.

Targeted tibio-peroneal re-entry during subintimal revascularization using the Outback® catheter.

BACKGROUND: Re-entry devices are used regularly in subintimal recanalization of chronic occlusions of the iliac and femoro-popliteal arteries and significantly contribute to the high success rate of these interventions. However, the use in tibio-peroneal arteries has only been described in few cases so far. The present work is a retrospective evaluation of the Outback® re-entry device for gaining targeted true lumen access at the level of the tibio-peroneal arteries. METHODS: From 9/2017 until 10/2020 the Outback® catheter was used in case of failed spontaneous re-entry at the level of the tibio-peroneal arteries in 14 patients either instead of the usual retrograde approach via a pedal/distal-crural access (n = 11) or in combination with it (n = 3). Baseline demographic and clinical data, morphologic characteristics of the occlusions, procedural succedss, as well as the Society of Vascular Surgery (SVS) runoff score before and after revascularization were documented. RESULTS: All patients (median age: 78 years; range: 66-93) suffered from peripheral artery occlusive disease Rutherford stage 4 to 6 with a median lesion length of 12 cm (range: 7-35). Technical and procedural success was achieved in all 14 patients. The mean re-entry accuracy was 0.25 cm (range: 0-0.8). The SVS runoff score improved from a median of 14.5 (interquartile range IQR: 10.8-16.4) to 7 (IQR: 6.3-7) (p < 0.01). CONCLUSIONS: The use of the Outback® catheter for targeted tibio-peroneal re-entry is associated with a high technical and procedural success rate and should be considered in case of otherwise failed ante- and retrograde recanalization.

Esophageal motility disorders in critically ill patients: a 24-hour manometric study.

OBJECTIVE: Impaired tubular esophageal motility is involved in the pathogenesis of gastroesophageal reflux disease, which, in turn, has been shown to cause nosocomial pneumonia in critically ill patients. As multiple factors are involved, this pilot study was undertaken to evaluate whether, similarly, impaired esophageal motility may contribute to nosocomial infections by determining esophageal motility in critically ill patients undergoing mechanical ventilation and sedation in comparison to that of a healthy control group. DESIGN: Open, single-centered study. PATIENTS AND METHODS: Fifteen consecutive ventilated intensive care unit (ICU) patients with different diseases and three regimens of analgo-sedation were included: group 1: no analgo-sedation, group 2: ketamine and benzodiazepines, and group 3: fentanyl and benzodiazepines. Six healthy volunteers were studied as controls. Twenty-four hour esophageal anterograde (propulsive) and retrograde motility changes were assessed by a manometry system. RESULTS: The frequencies of contractions were 0.67 +/- 0.1/min (no analgo-sedation) 0.093 +/- 0.02 (ketamine) and 0.076 +/- 0.01 (fentanyl) (p < 0.05 as compared to controls). The amplitudes (% of maximum) were 98 % (control), 58 % (analgo-sedation), 38 % (ketamine) and 42 % (fentanyl; p < 0.05 for the comparison of fentanyl and ketamine with controls). Whereas the percentage of propulsive contractions was significantly decreased in patients (no sedation: 45 %, ketamine: 34 %; fentanyl: 35 %, p < 0.05) as compared to controls (72 %), the percentage of retrograde contractions increased: no sedation: 29 %, ketamine: 34 % and fentanyl: 37 % as compared to controls: 10 %, p < 0.05. Analysis according to the underlying diseases showed marked inhibition of motility parameters within any disease group in comparison with controls. CONCLUSIONS: Irrespective of the underlying disease, propulsive motility of the esophageal body is significantly reduced during any kind of sedation in critically ill patients. Possibly central as well peripheral drug-related effects are involved in such a depression. Twenty-four hour motility recordings appear to be a valuable and feasible method to quantify and analyze esophageal motor disorders in critically ill patients.

[Effects of peptide YY on functions of the gastrointestinal tract]. / Die Wirkungen von Peptid YY auf Funktionen des Gastrointestinaltraktes.

The present report gives a review about the localization, release and gastrointestinal actions of peptide YY in different animal species and in humans. Possible mechanisms of action, the physiological and pathophysiological significance of peptide YY and the role of peptide YY 3-36 are discussed. Finally, unanswered questions are specified.

Effects of native and denatured whey proteins on plasminogen activator activity.

The plasmin system native to bovine milk consists of the caseinolytic serine proteinase plasmin; its inactive zymogen, plasminogen; plasminogen activators; and inhibitors. Evidence in the literature indicates that whey proteins may inhibit plasmin activity, but there is very little mention of their effect on plasminogen activators. The objective of this research was to determine the effect of both unheated and heat-denatured beta-lactoglobulin (beta-LG), alpha-lactalbumin (alpha-LA), and BSA on plasminogen activators. Plasminogen activator activity was significantly stimulated by non-heat treated and denatured alpha-LA as well as by denatured beta-LG. The stimulation effect by these whey proteins was kinetically characterized, which showed that all 3 significantly increased the rate of plasminogen activation. The stimulation effect was shown to be independent of any effect of the whey proteins on plasmin activity by testing 2 different substrates, d-Val-Leu-Lys p-nitroanilide (S-2251) and Spectrozyme PL (Spec PL), in a plasmin assay. Results using S-2251 confirmed the inhibitory effect of whey proteins on plasmin observed by several researchers. However, use of SpecPL did not suggest inhibition. Ligand binding studies showed this discrepancy to be due to significant interaction between S-2251 and the whey proteins. Overall, this study indicates that whey protein incorporation into cheese may not hinder plasmin activity and may stimulate plasminogen activation. Furthermore, the results indicate the need for careful consideration of the type of synthetic substrate chosen for model work involving whey proteins and the plasmin system.

[Differentiation of sphincter insufficiency and constipation after surgical anal atresia treatment: value of a new continence score]. / Differenzierung von Sphinkterinsuffizienz und Obstipation nach operierter Analatresie: Wertigkeit eines neuen Kontinenzscores.

Surgery of anorectal malformations was evaluated by continence scores, excluding constipation. The authors introduce a new score considering the case history and clinical parameters that differentiate sphincter insufficiency and overflow-incontinence due to constipation.

A clinical trial of a knowledge-based medical record.

To meet the needs of primary care physicians caring for patients with HIV infection, we developed a knowledge-based medical record to allow the on-line patient record to play an active role in the care process. These programs integrate the on-line patient record, rule-based decision support, and full-text information retrieval into a clinical workstation for the practicing clinician. To determine whether use of a knowledge-based medical record was associated with more rapid and complete adherence to practice guidelines and improved quality of care, we performed a controlled clinical trial among physicians and nurse practitioners caring for 349 patients infected with the human immuno-deficiency virus (HIV); 191 patients were treated by 65 physicians and nurse practitioners assigned to the intervention group, and 158 patients were treated by 61 physicians and nurse practitioners assigned to the control group. During the 18-month study period, the computer generated 303 alerts in the intervention group and 388 in the control group. The median response time of clinicians to these alerts was 11 days in the intervention group and 52 days in the control group (PJJ0.0001, log-rank test). During the study, the computer generated 432 primary care reminders for the intervention group and 360 reminders for the control group. The median response time of clinicians to these alerts was 114 days in the intervention group and more than 500 days in the control group (PJJ0.0001, log-rank test). Of the 191 patients in the intervention group, 67 (35%) had one or more hospitalizations, compared with 70 (44%) of the 158 patients in the control group (PJ=J0.04, Wilcoxon test stratified for initial CD4 count). There was no difference in survival between the intervention and control groups (P = 0.18, log-rank test). We conclude that our clinical workstation significantly changed physicians' behavior in terms of their response to alerts regarding primary care interventions and that these interventions have led to fewer patients with HIV infection being admitted to the hospital.