Photon-counting CT-angiography in pre-TAVR aortic annulus assessment: effects of retrospective vs. prospective ECG-synchronization on prosthesis valve selection.

To compare the diagnostic value of ultrahigh-resolution CT-angiography (UHR-CTA) compared with high-pitch spiral CTA (HPS-CTA) using a first-generation, dual-source photon-counting CT (PCD-CT) scanner for preprocedural planning of transcatheter aortic valve replacement (TAVR). Clinically referred patients with severe aortic valve stenosis underwent both, retrospective ECG-gated cardiac UHR-CTA (collimation: 120 × 0.2 mm) and prospective ECG-triggered aortoiliac HPS-CTA (collimation: 144 × 0.4 mm, full spectral capabilities) for TAVR planning from August 2022 to March 2023. Radiation dose was extracted from the CT reports, and the effective dose was calculated. Two radiologists analyzed UHR-CTA and HPS-CTA datasets, assessing the image quality of the aortic annulus, with regard to the lumen visibility and margin delineation using a 4-point visual-grading scale (ranges: 4 = "excellent" to 1 = "poor"). Aortic annulus area (AAA) measurements were taken for valve prosthesis sizing, with retrospective UHR-CTA serving as reference standard. A total of 64 patients were included (mean age, 81 years ± 7 SD; 28 women) in this retrospective study. HPS-CTA showed a lower radiation dose, 4.1 mSv vs. 12.6 mSv (p < 0.001). UHR-CTA demonstrated higher image quality to HPS-CTA (median score, 4 [IQR, 3-4] vs. 3 [IQR, 2-3]; p < 0.001). Quantitative assessments of AAA from both CTA datasets were strongly positively correlated (mean 477.4 ± 91.1 mm2 on UHR-CTA and mean 476.5 ± 90.4 mm2 on HPS-CTA, Pearson r2 = 0.857, p < 0.001) with a mean error of 22.3 ± 24.6 mm2 and resulted in identical valve prosthesis sizing in the majority of patients (91%). Patients with lower image quality on HPS-CTA (score value 1 or 2, n = 28) were more likely to receive different sizing recommendations (82%). Both UHR-CTA and HPS-CTA acquisitions using photon-counting CT technology provided reliable aortic annular assessments for TAVR planning. While UHR-CTA offers superior image quality, HPS-CTA is associated with lower radiation exposure. However, severely impaired image quality on HPS-CTA may impact on prosthesis sizing, suggesting that immediate post-scan image evaluations may require complementary UHR-CTA scanning.

Photon-counting computed tomography - clinical application in oncological, cardiovascular, and pediatric radiology. / Photon-Counting Computertomographie ­ klinische Anwendungen in der onkologischen, kardiovaskulären und pädiatrischen Radiologie.

BACKGROUND: Photon-counting detector computed tomography (PCD-CT) is a promising new technology with the potential to fundamentally change workflows in the daily routine and provide new quantitative imaging information to improve clinical decision-making and patient management. METHOD: The contents of this review are based on an unrestricted literature search of PubMed and Google Scholar using the search terms "photon-counting CT", "photon-counting detector", "spectral CT", "computed tomography" as well as on the authors' own experience. RESULTS: The fundamental difference with respect to the currently established energy-integrating CT detectors is that PCD-CT allows for the counting of every single photon at the detector level. Based on the identified literature, PCD-CT phantom measurements and initial clinical studies have demonstrated that the new technology allows for improved spatial resolution, reduced image noise, and new possibilities for advanced quantitative image postprocessing. CONCLUSION: For clinical practice, the potential benefits include fewer beam hardening artifacts, a radiation dose reduction, and the use of new or combinations of contrast agents. In particular, critical patient groups such as oncological, cardiovascular, lung, and head & neck as well as pediatric patient collectives benefit from the clinical advantages. KEY POINTS: · Photon-counting computed tomography (PCD-CT) is being used for the first time in routine clinical practice, enabling a significant dose reduction in critical patient populations such as oncology, cardiology, and pediatrics.. · Compared to conventional CT, PCD-CT enables a reduction in electronic image noise.. · Due to the spectral data sets, PCD-CT enables fully comprehensive post-processing applications.. CITATION FORMAT: · Hagen F, Soschynski M, Weis M et al. Photon-counting computed tomography - clinical application in oncological, cardiovascular, and pediatric radiology. Fortschr Röntgenstr 2024; 196: 25 - 34.

Improved mini-Tn7 Delivery Plasmids for Fluorescent Labeling of Stenotrophomonas maltophilia.

Fluorescently labeled bacterial cells have become indispensable for many aspects of microbiological research, including studies on biofilm formation as an important virulence factor of various opportunistic bacteria of environmental origin such as Stenotrophomonas maltophilia. Using a Tn7-based genomic integration system, we report the construction of improved mini-Tn7 delivery plasmids for labeling of S. maltophilia with sfGFP, mCherry, tdTomato and mKate2 by expressing their codon-optimized genes from a strong, constitutive promoter and an optimized ribosomal binding site. Transposition of the mini-Tn7 transposons into single neutral sites located on average 25 nucleotides downstream of the 3'-end of the conserved glmS gene of different S. maltophilia wild-type strains did not have any adverse effects on the fitness of their fluorescently labeled derivatives. This was demonstrated by comparative analyses of growth, resistance profiles against 18 antibiotics of different classes, the ability to form biofilms on abiotic and biotic surfaces, also independent of the fluorescent protein expressed, and virulence in Galleria mellonella. It is also shown that the mini-Tn7 elements remained stably integrated in the genome of S. maltophilia over a prolonged period of time in the absence of antibiotic selection pressure. Overall, we provide evidence that the new improved mini-Tn7 delivery plasmids are valuable tools for generating fluorescently labeled S. maltophilia strains that are indistinguishable in their properties from their parental wild-type strains. IMPORTANCE The bacterium S. maltophilia is an important opportunistic nosocomial pathogen that can cause bacteremia and pneumonia in immunocompromised patients with a high rate of mortality. It is now considered as a clinically relevant and notorious pathogen in cystic fibrosis patients but has also been isolated from lung specimen of healthy donors. The high intrinsic resistance to a wide range of antibiotics complicates treatment and most likely contributes to the increasing incidence of S. maltophilia infections worldwide. One important virulence-related trait of S. maltophilia is the ability to form biofilms on any surface, which may result in the development of increased transient phenotypic resistance to antimicrobials. The significance of our work is to provide a mini-Tn7-based labeling system for S. maltophilia to study the mechanisms of biofilm formation or host-pathogen interactions with live bacteria under non-destructive conditions.

Clinical outcomes of transcatheter aortic valve implantation in patients younger than 70 years rejected for surgery: the AMTRAC registry.

BACKGROUND: The mean age of transcatheter aortic valve implantation (TAVI) patients is steadily decreasing. AIMS: The aim of the study was to describe the characteristics, the indications for and the outcomes of TAVI in patients <70 years old. METHODS: All patients undergoing TAVI (n=8,626) from the 18 participating centres between January 2007 and June 2020 were stratified by age (70). For patients <70, the indications for TAVI were extracted from Heart Team discussions and the baseline characteristics and mortality were compared between the two groups. RESULTS: Overall, 640 (7.4%) patients were <70 (9.1% during 2018-2020, p<0.001); the mean age was 65.0±2.3 years. The younger patients were more often male, with bicuspid valves or needing valve-in-valve procedures. They had a higher prevalence of lung disease and diabetes. In 80.7% of cases, the Heart Team estimated an increased surgical risk and TAVI was selected, reflected by an STS score >4% in 20.4%. Five-year mortality was similar (29.4 vs 29.8%, HR 0.95, p=0.432) in the <70 and >70 groups. In the <70 group, mortality was higher for those referred for TAVI due to an increased surgical risk compared to those referred for other reasons (31.6 vs 24.5%, HR 1.23, p=0.021). Mortality was similar regardless of the STS stratum in patients judged by the Heart Team to be at increased surgical risk (32.6 vs 30.4%, HR 0.98, p=0.715). CONCLUSIONS: Use of TAVI in patients <70 is becoming more frequent. The main reason for choosing TAVI is due to an increased surgical risk not adequately represented by the STS score. The outcomes for these patients are similar to those for older TAVI patients. Dedicated trials of TAVI/SAVR in younger patients are needed to guide decisions concerning expansion of TAVI indications. ((ClinicalTrials.gov: NCT04031274).

Prognostic impact of invasive exercise haemodynamics in patients with severe mitral regurgitation.

OBJECTIVES: Abnormal invasive exercise haemodynamics in asymptomatic patients with severe mitral regurgitation were associated with higher regurgitation burden. We analysed the association between parameters of invasive exercise testing with mortality and valve surgery compared to guideline defined non-invasive criteria. METHODS: This single centre, retrospective cohort study assesses the association of invasive exercise haemodynamics and mortality with and without surgery in patients with severe mitral regurgitation and normal ejection fraction (≥55%) as primary outcome. The secondary outcome was the need for mitral valve surgery in 113 asymptomatic patients primarily managed conservatively. RESULTS: We identified 314 patients [age 59 years (standard deviation 13), 27% female] with available exercise haemodynamics with a median follow-up of 8.2 (interquartile range 5.2-11.2) years. Five-year survival rate was 93.0%. Pulmonary capillary wedge pressure at maximum exercise >30 mmHg was the only parameter independently associated with mortality after adjustment for age and guideline criteria [hazard ratio (HR) 2.7 (1.3-5.6), P = 0.007]. In the 113 patients primarily managed conservatively, maximum pulmonary capillary wedge pressure was independently associated with mitral valve surgery during follow-up in multivariable analysis (HR 2.10 (1.32-3.34), P = 0.002; after adjustment for workload and weight: HR 1.31 (1.14-1.52), P < 0.001], whereas systolic pulmonary artery pressure and current guideline criteria were not. Adding maximum pulmonary capillary wedge pressure >25 mmHg improved the predictive power of current guideline criteria for surgery (area under the curve 0.61-0.68, P = 0.02). CONCLUSIONS: Invasive exercise haemodynamics predict mortality and improve prognostic information about surgery during follow-up derived from current guideline criteria in asymptomatic patients with severe mitral regurgitation.

Predictors for low TAVI-prosthesis position assessed by fusion imaging of pre- and post-procedural CT angiography.

BACKGROUND: Low prosthesis position after transcatheter aortic valve implantation (TAVI) is associated with higher rates of new onset conduction disturbances and permanent pacemaker implantations. Purpose of this study was to investigate possible predictors of a low prosthesis position of the SAPIEN 3 (Edwards Lifesciences, Irvine, California, USA) valve type using fusion imaging of pre- and post-procedural computed tomography angiography (CTA). METHODS: CTA fusion imaging was performed in 120 TAVI-patients with 3D-reconstruction of the transcatheter heart valve (THV) position within the device landing zone. A low implantation position was defined according to the manufacturer's recommendations as > 30% of the prosthesis below the native annulus plane. RESULTS: A low THV position was found in 17 patients (14%). Patients with low THV position had less calcification of the annulus region and a smaller annulus size compared to patients with a normal or high THV position (P = 0.003 and 0.041, respectively). The only independent predictor of a low THV position in multivariate logistic regression analysis was the extent of calcification of the cusp region (odds ratio [CI] 0.842 [0.727-0.976], P = 0.022). CONCLUSIONS: Fusion imaging of pre-and post-procedural CTA identified reduced calcification of the cusp region as an independent predictor of a low THV position of the SAPIEN 3. This should be considered when planning the TAVI procedure. Correlation of cusp region calcification and prosthesis position after TAVI.

Impact of On-Clopidogrel Platelet Reactivity on Incidence of Hypoattenuated Leaflet Thickening After Transcatheter Aortic Valve Replacement.

OBJECTIVES: To assess the impact of on-clopidogrel platelet reactivity (PR) on HALT, the authors prospectively tested whether patients with below-median on-clopidogrel PR have a lower incidence of HALT compared with those with above-median on-clopidogrel PR. BACKGROUND: It is unclear whether the apparent ineffectiveness of clopidogrel in preventing hypoattenuated leaflet thickening (HALT) after transcatheter aortic valve replacement (TAVR) questions the concept of P2Y12 inhibition after TAVR or is a consequence of an inadequate response to clopidogrel in elderly patients with severe aortic stenosis. METHODS: Patients were either on long-term dual antiplatelet therapy with clopidogrel and acetylsalicylic acid or were given bolus doses of both drugs the day before TAVR. Adenosine diphosphate (ADP)-induced multielectrode impedance aggregometry was performed before TAVR. After TAVR, clopidogrel was continued in all patients. Computed tomographic angiography was performed to detect HALT. RESULTS: Of 331 patients enrolled, computed tomographic angiography was performed in 200 at 5 days (interquartile range: 4 to 6 days). Among patients with below-median ADP-induced PR (<180 AU · min), 16 were diagnosed with HALT, whereas 20 patients with above-median PR were diagnosed with HALT (p = 0.58). Among patients with high on-clopidogrel PR (>468 AU · min; n = 29), 7 (24%) displayed HALT, compared with 19 (17%) with ADP-induced PR ≤468 AU · min (p = 0.43). Consistently, ADP-induced PR as a continuous variable was not significantly associated with HALT (p = 0.75). Oral anticoagulation was associated with reduced rates of HALT (odds ratio: 0.41; 95% CI: 0.18 to 0.96; p = 0.04). CONCLUSIONS: On-clopidogrel ADP-induced PR was not significantly associated with the occurrence of HALT. In contrast, oral anticoagulation was associated with reduced rates of HALT.

Impact of the type of transcatheter heart valve on the incidence of early subclinical leaflet thrombosis.

OBJECTIVES: The aim of this study was to investigate whether balloon-expandable and self-expandable transcatheter heart valves (THVs) differ in terms of the incidence of early subclinical leaflet thrombosis (LT). METHODS: Electrocardiographic-gated cardiac dual-source computed tomography angiography was performed at a median of 5 days after transcatheter aortic valve implantation and assessed for evidence of LT. RESULTS: Of the 629 consecutive patients, 538 (86%) received a balloon-expandable THV and 91 (14%) a self-expandable THV. LT was documented in 77 (14%) patients with a balloon-expandable valve and in 16 (18%) with a self-expandable valve (P = 0.42). Similarly, LT was not significantly related to THV size (P = 0.62). Corresponding to a lower rate of atrial fibrillation in the group with LT [25 (27%) vs 222 (41%), P = 0.01], anticoagulation at the time of computed tomography angiography was less frequent in this group [21 (23%) vs 183 (34%), P = 0.03]. Among the other potentially relevant covariables, there was no significant difference in the clinical baseline and the procedural characteristics between patients with and without LT (age 82 ± 6 years vs 82 ± 6 years, P = 0.51; ejection fraction 49 ± 10% vs 50 ± 10%, P = 0.47). In multivariate logistic regression analysis, including potentially relevant covariables, valve type was not significantly associated with LT (P = 0.36). In the univariate and multivariate analyses, only the lack of anticoagulation at the time of computed tomography angiography was predictive of thrombus formation [0.563 (0.335-0.944), P = 0.03; 0.576 (0.343-0.970), P = 0.04]. CONCLUSIONS: In this large retrospective study of 629 patients, the type and the size of THV was not predictive of early LT.

Suppression of APC/CCdh1 has subtype specific biological effects in acute myeloid leukemia.

The E3 ubiquitin ligase and tumor suppressor APC/CCdh1 is crucial for cell cycle progression, development and differentiation in many cell types. However, little is known about the role of Cdh1 in hematopoiesis. Here we analyzed Cdh1 expression and function in malignant hematopoiesis. We found a significant decrease of Cdh1 in primary acute myeloid leukemia (AML) blasts compared to normal CD34+ cells. Thus, according to its important role in connecting cell cycle exit and differentiation, decreased expression of Cdh1 may be a mechanism contributing to the differentiation block in leukemogenesis. Indeed, knockdown (kd) of Cdh1 in HL-60 cell line (AML with maturation, FAB M2) led to less differentiated cells and a delay in PMA-induced differentiation. Acute promyelocytic leukemia (APL, FAB M3) is an AML subtype which is highly vulnerable to differentiation therapy with all-trans retinoic acid (ATRA). Accordingly, we found that APL is resistant to a Cdh1-kd mediated differentiation block. However, further depletion of Cdh1 in APL significantly reduced viability of leukemia cells upon ATRA-induced differentiation. Thus, low Cdh1 expression may be important in AML biology by contributing to the differentiation block and response to therapy depending on differences in the microenvironment and the additional genetic background.

Monitoring bortezomib therapy in multiple myeloma: screening of cyclin D1, D2, and D3 via reliable real-time polymerase chain reaction and association with clinico-pathological features and outcome.

Cyclins D1, D2, and D3 (CCND1, 2, 3) are regulated by proteasomal degradation. Their overexpression in multiple myeloma (MM) has prognostic value. We performed this pilot study to analyze a possible association between CCND1-3 overexpression and response to treatment with the proteasome inhibitor bortezomib, since a specific prognostic marker for bortezomib response has not been reported, but would be ideal to predict who benefits most from bortezomib in times of several potentially efficient therapeutic options. Bone marrow (BM) specimens of 20/47 consecutive patients were available for reliable CCND1-3 analyses by real-time PCR. With CCND1 overexpression in 9/20 patients, the risk for progression after bortezomib treatment was significantly decreased (HR 0.102, 95% CI 0.021-0.498, p = 0.0048) and progression-free survival substantially prolonged (p = 0.0011). Our study is the first to suggest that overexpressed CCND1 in MM is an independent prognostic marker associated with a more durable response to bortezomib. These preliminary results warrant a larger study.