Sensitivity of Thoracic Digital Tomosynthesis (DTS) for the Identification of Lung Nodules

Thoracic computed tomography (CT) is considered the gold standard for detection lung pathology, yet its efficacy as a screening tool in regards to cost and radiation dose continues to evolve. Chest radiography (CXR) remains a useful and ubiquitous tool for detection and characterization of pulmonary pathology, but reduced sensitivity and specificity compared to CT. This prospective, blinded study compares the sensitivity of digital tomosynthesis (DTS), to that of CT and CXR for the identification and characterization of lung nodules. Ninety-five outpatients received a posteroanterior (PA) and lateral CXR, DTS, and chest CT at one care episode. The CXR and DTS studies were independently interpreted by three thoracic radiologists. The CT studies were used as the gold standard and read by a fourth thoracic radiologist. Nodules were characterized by presence, location, size, and composition. The agreement between observers and the effective radiation dose for each modality was objectively calculated. One hundred forty-five nodules of greatest diameter larger than 4 mm and 215 nodules less than 4 mm were identified by CT. DTS identified significantly more >4 mm nodules than CXR (DTS 32 % vs. CXR 17 %). CXR and DTS showed no significant difference in the ability to identify the smaller nodules or central nodules within 3 cm of the hilum. DTS outperformed CXR in identifying pleural nodules and those nodules located greater than 3 cm from the hilum. Average radiation dose for CXR, DTS, and CT were 0.10, 0.21, and 6.8 mSv, respectively. Thoracic digital tomosynthesis requires significantly less radiation dose than CT and nearly doubles the sensitivity of that of CXR for the identification of lung nodules greater than 4 mm. However, sensitivity and specificity for detection and characterization of lung nodules remains substantially less than CT. The apparent benefits over CXR, low cost, rapid acquisition, and minimal radiation dose of thoracic DTS suggest that it may be a useful procedure. Work-up of a newly diagnosed nodule will likely require CT, given its superior cross-sectional characterization. Further investigation of DTS as a diagnostic, screening, and surveillance tool is warranted.     

COMPASS 31: A Refined and Abbreviated Composite Autonomic Symptom Score

ObjectiveTo develop a concise and statistically robust instrument to assess autonomic symptoms that provides clinically relevant scores of autonomic symptom severity based on the well-established 169-item Autonomic Symptom Profile (ASP) and its validated 84-question scoring instrument, the Composite Autonomic Symptom Score (COMPASS).Patients and MethodsWe assessed the internal consistency of COMPASS using Cronbach α coefficients based on the ASP of 405 healthy control subjects recruited and seen in the Mayo Clinic Autonomic Disorders Center between March 1, 1995, and March 31, 2010. Applying a simplified scoring algorithm, we then used exploratory factor analysis with orthogonal rotation and eigenvalue calculations to extract internally consistent domains and to reduce dimensionality. This analysis was followed by expert revisions to eliminate redundant content and to retain clinically important questions and final assessment of the new instrument.ResultsThe new simplified scoring algorithm alone resulted in higher Cronbach α values in all domains. Factor analysis revealed 7 domains with a total of 54 questions retained. Expert revisions resulted in further reduction of questions and domains with a remaining total of 31 questions in 6 domains (COMPASS 31). Measures of internal consistency were much improved compared to those for COMPASS. Following appropriate weighting, this instrument provides an autonomic symptom score from 0 to 100.ConclusionCOMPASS 31 is a refined, internally consistent, and markedly abbreviated quantitative measure of autonomic symptoms. It is based on the original ASP and COMPASS, applies a much simplified scoring algorithm, and is suitable for widespread use in autonomic research and practice.