Compositional mapping of surfaces in atomic force microscopy

We propose a method for mapping the composition of a surface by using an amplitude modulation atomic force microscope operated without tip-surface mechanical contact. The method consists in exciting the first two modes of the microcantilever. The nonlinear dynamics of the tip motion, the coupling of its first two modes, and the sensitivity of the second mode to long-range attractive forces allows us to use this mode to probe compositional changes while the signal from the first mode is used to image the sample surface. We demonstrate that the second mode has a sensitivity to surface force variations below 10−11 N.The authors acknowledge helpful discussions with A. San Paulo. This work was financially supported by then Dirección General de Investigación Científica y Técnica of Spain (PB98-0471) and the European Commission (MONA-LISA, G5RD-CT-2000-00349).Peer reviewe

Use of full-dose contrast-enhanced CT for extrahepatic staging using Gallium-68-DOTATATE PET/CT in patients with neuroendocrine tumors

PURPOSEStudies have demonstrated that positron emission tomography/computed tomography (PET/CT) with Gallium-68 (68Ga)-labeled somatostatin analogues are effective at detecting metastatic disease in neuroendocrine tumors (NET), especially extrahepatic metastases. However, PET in combination with full-dose contrast-enhanced CT (ceCT) exposes patients to higher radiation (~25 mSv). The use of non-contrast-enhanced low-dose CT (ldCT) can reduce radiation to about 10 mSv and may avoid contrast-induced side effects. This study seeks to determine whether ceCT could be omitted from NET assessments.METHODSWe retrospectively compared the performance of PET/ldCT versus PET/ceCT in 54 patients (26 male, 28 female) who had undergone a 68Ga-DOTATATE PET/CT. The selection criteria were as follows: available ldCT and ceCT, histologically confirmed NET, and follow-up of at least 6 months (median, 12.6 months; range, 6.1–23.2 months). The PET/ldCT and PET/ceCT images were analyzed separately. We reviewed metastases in the lungs, bones, and lymph nodes. The results were compared with the reference standard (clinical follow-up data).RESULTSThe PET/ceCT scans detected 139 true-positive bone lesions compared with 140 lesions detected by the PET/ldCT scans, 106 true-positive lymph node metastases (PET/ceCT) compared with 90 metastases detected by the PET/ldCT scans, and 26 true-positive lung lesions (PET/ceCT) compared with 6 lesions detected by the PET/ldCT scans. The overall lesion-based sensitivity for full-dose PET/ceCT was 97%, specificity 86%, negative predictive value (NPV) 93%, and positive predictive value (PPV) 93%. The overall lesion-based sensitivity for PET/ldCT was 85%, specificity 73%, NPV 72%, and PPV 85%.CONCLUSIONThis study presents the first evidence that ceCT should not be omitted from extrahepatic staging using 68Ga-DOTATATE PET/CT in patients with NET. ceCT alone can be used as a follow-up to reduce radiation exposure when the patient has already undergone PET/ceCT and suffers from non-DOTATATE-avid NET

Associations between Covariates and Pneumothorax Observations in CT-Guided Lung Biopsies

The purpose of this study is to assess the effect of nine covariates on the occurrence or absence of stable or symptomatic pneumothorax. Forty-three patients underwent CT-guided lung biopsies from January 2020 to January 2022 (24 m, 19 f, median age 70 years). All the interventions were carried out with a semi-automatic 18G needle and a 17G trocar in a prone or supine position. Different covariates were measured and correlated to the rate and severity of the pneumothoraces observed. Nominal two-sided t-test p-values for the continuous variables and Fisher’s exact test results for the categorical variables were conducted. The data included the lesion size, distance to the pleura, needle-pleura angle, age, gender, position during the procedure, and the presence of chronic obstructive pulmonary disease. Patients with an observed pneumothorax had an average angle between the needle and the pleura of 74.00° compared to 94.68° in patients with no pneumothorax (p-value = 0.028). A smaller angle measurement correlated with a higher risk of pneumothorax development. The needle-pleural angle plays a vital role in the outcome of a CT-guided lung biopsy. Correctly adjusting the needle-pleural angle can diminish the pneumothorax risk associated with a CT-guided lung biopsy. The study results show that as the needle’s angle deviates from the perpendicular, the pleural surface area experiencing trauma increases, and pneumothorax is more likely to occur

Associations between Covariates and Pneumothorax Observations in CT-Guided Lung Biopsies

The purpose of this study is to assess the effect of nine covariates on the occurrence or absence of stable or symptomatic pneumothorax. Forty-three patients underwent CT-guided lung biopsies from January 2020 to January 2022 (24 m, 19 f, median age 70 years). All the interventions were carried out with a semi-automatic 18G needle and a 17G trocar in a prone or supine position. Different covariates were measured and correlated to the rate and severity of the pneumothoraces observed. Nominal two-sided t-test p-values for the continuous variables and Fisher’s exact test results for the categorical variables were conducted. The data included the lesion size, distance to the pleura, needle-pleura angle, age, gender, position during the procedure, and the presence of chronic obstructive pulmonary disease. Patients with an observed pneumothorax had an average angle between the needle and the pleura of 74.00° compared to 94.68° in patients with no pneumothorax (p-value = 0.028). A smaller angle measurement correlated with a higher risk of pneumothorax development. The needle-pleural angle plays a vital role in the outcome of a CT-guided lung biopsy. Correctly adjusting the needle-pleural angle can diminish the pneumothorax risk associated with a CT-guided lung biopsy. The study results show that as the needle’s angle deviates from the perpendicular, the pleural surface area experiencing trauma increases, and pneumothorax is more likely to occur

Safe Zone to Avoid Pneumothorax in a CT-Guided Lung Biopsy

Pneumothorax is one of the most frequent complications of computed tomography (CT)-guided lung biopsies. We aim to identify the safe zone of the needle–pleura angle during a CT-guided lung biopsy. Fifty-two patients underwent CT-guided lung biopsies between January 2020 and September 2022 (27 males, 25 females, median age 70 years). Right and left needle angles were measured and correlated to the incidence of pneumothorax. The minimum delta (δmin) was calculated as the absolute value of the difference between a 90° angle and the right and left angles. t-test p-values for δmin were conducted. We recorded 29 patients with pneumothorax, including intraprocedural and transient, postprocedural with minimal symptoms, or postprocedural requiring a chest tube insertion. Thirty-two patients had a δmin ≥ 10°, while 20 had a δmin < 10°. Of the patients with a δmin < 10°, 30% experienced pneumothorax compared to 71.8% in patients with δmin ≥ 10° (p = 0.0023). The study results show that as the needle’s angle deviates from the perpendicular, with an absolute value of more than 10°, the likelihood of pneumothorax increases significantly. A needle–pleura angle between 80° and 100° gives the operator a safe zone to reduce the risk of pneumothorax

Western Star, 1913-09-24

The Western Star began publication on Newfoundland's west coast on 4 April 1900, appearing weekly with brief semiweekly periods up to 1952, when it became a daily. As of 17 April 2019 it continues as a free weekly community paper