Complications from computed tomography-guided core needle biopsy for patients receiving stereotactic body radiation therapy for early-stage lesions of the lung.

BACKGROUND: Obtaining a tissue diagnosis has traditionally been standard practice before initiating therapy for early-stage non-small-cell lung cancer (NSCLC). In several recent studies from Europe and Asia, a substantial proportion of patients have received stereotactic body radiation therapy (SBRT) based only on the imaging characteristics of the suspicious lesion. The underlying assumption is that the risk of percutaneous needle biopsy may outweigh the benefits in a population that generally has underlying pulmonary dysfunction and other medical comorbidity. Nevertheless, there is limited information regarding biopsy-related complication rates in high-risk patients with early-stage NSCLC who are treated with SBRT. MATERIALS AND METHODS: This was a retrospective review of outcomes after biopsy in patients treated with SBRT. Complications of percutaneous core needle biopsy were analyzed in relation to patient and tumor characteristics. Each biopsy event was analyzed independently for patients with multiple biopsies. RESULTS: A total of 112 percutaneous biopsies were performed in 103 patients. Pneumothorax of any degree was observed in 40 patients (35%) (95% CI, 27%-45%), and 12 patients (10.7%) had a clinically significant pneumothorax requiring chest tube placement (95% CI, 6%-18%). The time to first fraction of SBRT was not different in patients who had a pneumothorax or placement of a chest tube. On multivariate analysis, age, performance status, smoking history, pack-years of smoking, chronic obstructive pulmonary disease history, and forced expiratory volume in the first second of expiration were not statistically significantly associated with chest tube placement. CONCLUSION: Computed tomography-guided needle biopsy in a primarily medically inoperable patient population is safe, with an acceptable degree of complications.

Extracting the Chern number from the dynamics of a Fermi gas: implementing a quantum Hall bar for cold atoms.

We propose a scheme to measure the quantized Hall conductivity of an ultracold Fermi gas initially prepared in a topological Chern insulating phase and driven by a constant force. We show that the time evolution of the center of mass, after releasing the cloud, provides a direct and clear signature of the topologically invariant Chern number. We discuss the validity of this scheme, highlighting the importance of driving the system with a sufficiently strong force to displace the cloud over measurable distances while avoiding band-mixing effects. The unusual shapes of the driven atomic cloud are qualitatively discussed in terms of a semiclassical approach.