Native T1 Relaxation Time and Extracellular Volume Fraction as Accurate Markers of Diffuse Myocardial Fibrosis in Heart Valve Disease　- Comparison With Targeted Left Ventricular Myocardial Biopsy.

BACKGROUND: The aim of our study was to investigate the relationship between the cardiac magnetic resonance (CMR)-derived native T1 relaxation time and myocardial extracellular volume (ECV) fraction and the extent of diffuse myocardial fibrosis (DMF) on targeted myocardial left ventricular (LV) biopsy. METHODS AND RESULTS: The study population consisted of 40 patients (age 63±8 years, 65% male) undergoing valve and/or ascending aorta surgery for severe aortic stenosis (77.5%), root dilatation (7.5%) or valve regurgitation (15%). The T1 relaxation time was assessed in the basal interventricular septum pre- and 10-min post-contrast administration using the modified Look-Locker Inversion recovery sequence prior to surgery. LV myocardial biopsy specimen was obtained during surgery from the basal interventricular septal segment matched with the T1 mapping assessment. The percentage of myocardial collagen was quantified using picrosirius red staining. The average percentage of myocardial collagen was 22.0±14.8%. Both native T1 relaxation time with cutoff value ≥1,010 ms (sensitivity=90%, specificity=73%, area under the curve=0.82) and ECV with cutoff value ≥0.32 (sensitivity=80%, specificity=90%, area under the curve=0.85) showed high accuracy to identify severe (>30%) DMF. The native T1 relaxation time showed significant correlation with LV mass (P<0.01). CONCLUSIONS: Native T1 relaxation time and ECV at 10 min after contrast administration are accurate markers of DMF. (Circ J 2016; 80: 1202-1209).

Comparison of dose length product and image quality of a biphasic whole-body polytrauma CT protocol with and without the automatic tube voltage selection.

BACKGROUND AND AIMS: A significant source of man-made radiation is now linked to medical devices especially X-ray imaging based ones like CT scans which expose the body to cumulative ionizing radiation and thus attendant cancer risks. The aim of this study was to determine whether using a combination of Automatic Tube Current Modulation (ATCM) and Automatic Tube Voltage Selection (ATVS) during two-phase whole-body CT (2PWBCT) examinations would reduce the radiation dose while preserving the image quality. PATIENTS AND METHODS: This was a prospective, observational, single-centre study of 127 adult patients who had undergone the 2PWBCT polytraumatic protocol. All were examined on a Somatom Drive scanner (Siemens). The patients were divided into two groups: ATCM only (42 patients) and ATCM +ATVS (85 patients). Patients' arm positions during examination and the examination dose length product (DLP) values were recorded, as well the standard deviations (SD) of the density in reference areas on CT scans for the image quality assessment. The DLP values and image quality in the groups were compared using ANOVA. RESULTS: Mean Total DLP (in mGy*cm): ATCM only: 3337 +/-797, ATCM+ATVS: 3402 +/-830; P=0.674. No effect of arm position (P=0.586). Mean density SD values in reference areas (in HU) in ATCM only: 49 +/-45, 15 +/-6, 9 +/-2, 12 +/-4, 10 +/-3, in ATCM+ATVS: 48 +/-45, 17 +/-6, 11 +/-3, 15 +/-6, 12 +/-4. SD values was higher in ATCM+ATVS group (P<0.001). CONCLUSION: Combination of ATVS and ATCM in polytraumatic 2PWBCT leads to no significant radiation load reduction compared with ATCM only but does lead to a slight degradation of image quality. The radiation load is significantly reduced if the patient has their arms behind the head when scanning, regardless of the activation of ATVS.

OPTIMISATION OF ABDOMINAL CT EXAM PROTOCOLS IN OBESE PATIENTS.

Obesity is marked as a global epidemic, and the number of obese people is steadily increasing. This disease affects various aspects of health care, which also includes radiodiagnostic imaging modalities. CT exams of bariatric patients are becoming common in radiological practice and bring problems of both technical and physical nature. Obesity affects the quality of CT images, therefore, optimisation of the used CT protocols is important, which is difficult to be carried out on patients, because of the principles of radiation protection and ethical point of view. This study evaluates and compares three available CT protocols for examination of the abdomen in terms of image quality, radiation dose and scan time on two CT scanners of the manufacturer Siemens. For optimisation, an anthropomorphic phantom of the abdomen was used, which, by its size and attenuation of the used materials, suitably simulated an obese patient.

A systematic review of conversion factors between kerma-area product and effective/organ dose for cardiac interventional fluoroscopy procedures performed in adult and paediatric patients.

The aim of this systematic review is to undertake a critical appraisal of the evidence in the published literature concerning the conversion factors between kerma-area product (PKA) and effective/organ dose (DCED_PKA, DCHT_PKA) for cardiac interventional fluoroscopy procedures performed in adults and paediatric patients and to propose reference conversion factors to help standardize dose calculations. A search strategy utilizing MeSH headings in three databases identified 59 (adult) and 37 (paediatric) papers deemed eligible for the review. Exclusion criteria were adopted to select data only from publications which established DCED_PKAin patients using the ICRP 103 tissue weighting factors. A time restriction from January 2007 was introduced in the search to capture the evolving trends of utilization of fluoroscopy-guided intervention technologies only in recent years. The suggested DCED_PKAand DCHT_PKAwere synthesized by calculating the weighted averages of the values reported by the authors with weights corresponding to the study sample size. Eighteen studies for both adult (9) and paediatric (9) patients matching the search terms fulfilled the inclusion criteria. The suggested value for DCED_PKAin adult patients amounts to 0.24 mSv Gy-1cm-2. The suggested values for DCHT_PKAranged from a minimum of 0.15 mSv Gy-1cm-2for the female breast to a maximum of 0.97 mSv Gy-1cm-2for the lungs. The suggested values for DCED_PKAin paediatric patients ranged from 3.45 mSv Gy-1cm-2for the new-born to 0.49 mSv Gy-1cm-2in the 15 years age class. The suggested values for DCHT_PKAranged from a minimum of 0.33 mSv Gy-1cm-2for bone marrow in the 15 years age class to a maximum of 11.49 mSv Gy-1cm-2for the heart in the new-born. To conclude, values of DCED_PKA/DCHT_PKAwere provided for calculating effective/organ doses in cardiac interventional procedures. They can be useful for standardizing dose calculations, hence for comparison of the radiation detriment from different imaging procedures and in the framework of epidemiologic studies.

Selective coronary angiography, percutaneous coronary intervention and asymptomatic peri-procedural myocardial injury.

BACKGROUND: While there have been a number of studies reporting the incidence and implications of elevated troponin levels after percutaneous coronary intervention (PCI), the body of information about the incidence, associations, and implications of elevated troponin levels following coronary angiography (CAG) is limited. MATERIALS AND METHODS: A total of 220 consecutive patients with stable coronary artery disease or intermediate or low-risk acute coronary syndrome without persistent ST-segment elevation (NSTE-ACS) were included in our study. High-sensitivity cardiac troponin I (hs-cTnI) levels were measured before and after coronary angiography (CAG) in patients with or without PCI and correlated with a number of clinical variables. RESULTS: Hs-cTnI elevations above the 99th percentile upper reference limit (URL), or above 20% of the initially positive, yet already declining values, were found in 60 (37.2%) patients after CAG and in 45 (76.2%) patients undergoing PCI. Significant correlations of hs-cTnI elevation were found with the following variables: volume of contrast, fluoroscopy time, dose-area product, amount of contrast agent injected directly into the coronary arteries, total time of balloon dilation and the number and total length of implanted stents (P<0.001 for all). CONCLUSION: While an asymptomatic elevation of hs-cTnI is a common finding after PCI, it does occur, quite surprisingly, also after CAG. Despite contradictory views regarding the clinical relevance of asymptomatic post-procedural elevated hs-cTnI levels, it is generally believed that a mild elevation is not associated with an increased risk. Still, it may pose a diagnostic quandary following a successful interventional procedure and even more so after an uncomplicated CAG. TRIAL REGISTRATION: Clinicaltrials.gov - NCT02960321.

New Imaging Markers of Clinical Outcome in Asymptomatic Patients with Severe Aortic Regurgitation.

Background: Determining the value of new imaging markers to predict aortic valve (AV) surgery in asymptomatic patients with severe aortic regurgitation (AR) in a prospective, observational, multicenter study. Methods: Consecutive patients with chronic severe AR were enrolled between 2015-2018. Baseline examination included echocardiography (ECHO) with 2- and 3-dimensional (2D and 3D) vena contracta area (VCA), and magnetic resonance imaging (MRI) with regurgitant volume (RV) and fraction (RF) analyzed in CoreLab. Results: The mean follow-up was 587 days (interquartile range (IQR) 296-901) in a total of 104 patients. Twenty patients underwent AV surgery. Baseline clinical and laboratory data did not differ between surgically and medically treated patients. Surgically treated patients had larger left ventricular (LV) dimension, end-diastolic volume (all p < 0.05), and the LV ejection fraction was similar. The surgical group showed higher prevalence of severe AR (70% vs. 40%, p = 0.02). Out of all imaging markers 3D VCA, MRI-derived RV and RF were identified as the strongest independent predictors of AV surgery (all p < 0.001). Conclusions: Parameters related to LV morphology and function showed moderate accuracy to identify patients in need of early AV surgery at the early stage of the disease. 3D ECHO-derived VCA and MRI-derived RV and RF showed high accuracy and excellent sensitivity to identify patients in need of early surgery.

Impact of the Ceiling-Mounted Radiation Shielding Position on the Physician's Dose from Scatter Radiation during Interventional Procedures.

The effect of the ceiling-mounted radiation shielding on the amount of the scatter radiation was assessed under conditions simulating obese patients for clinically relevant exposure parameters. Measurements were performed in different projections and with different positions of the ceiling-mounted shielding: without shielding; shielding closest to the patient; and shielding closest to the physician performing the procedure. The protection provided by the shielding was assessed for cardiology when the femoral access is used and for radiology when the physician performs the procedure in the abdominal area. The results show that the use of the ceiling-mounted shielding can decrease the dose from the scatter radiation by 95% at the position of the performing physician. In cardiology, the impact is more pronounced when the left oblique projection is used. In radiology, a large decrease was observed for right oblique projections, compared to cardiology. The ceiling-mounted shielding should be placed as close to the physician as possible. The idea of creating the largest radiation shadow by placing the radiation shielding as close to the patient as possible does not provide as effective radiation protection of the operator as it might be thought.