RESUMO
Study Objectives: The initial imaging modality recommended by the American College of Radiology for suspected hand and wrist fractures is radiography. As there are radiation exposure risks associated with radiography, 2D ultrasound (2DUS) has also been investigated for diagnosis of these injuries. While sensitive and specific, 2DUS is operator dependent, requiring expertise to acquire and interpret images. 3DUS by novices is little studied in orthopedic evaluation. We aimed to determine whether novice-acquired 3DUS with expert or novice readers can identify hand and wrist fractures. We hypothesized that expert and novice interpretations of novice-acquired 3DUS of orthopedic injuries would show high agreement with each other and with the reference standard. Methods: The STARD criteria for studies of diagnostic tests were applied. Following IRB approval and informed consent, we prospectively enrolled subjects at a tertiary care academic medical center and an associated orthopedic clinic. We estimated a sample size of 70 subjects for an intraclass correlation coefficient (ICC) 0.7 (with alpha of 0.5 and power 0.8) and to detect kappa of 0.8. A single novice operator third-year medical student (MS3) performed all image acquisitions without any specific effort to identify anatomy or injuries during acquisition. 2D B mode US images were acquired using a Philips Lumify L12-4 transducer connected to a smartphone, and paired to an inertial measurement unit. All scans were reconstructed in volume rendering mode and displayed in 3DSlicer, an open-source visualization tool. Scans were interpreted by three groups of readers: 2 MS3s (novice), 3 emergency physicians with US fellowship training, and 2 board certified radiologists with musculoskeletal fellowship training (expert). The reference standard was board-certified radiologist interpretation of x-rays obtained during routine clinical care. Readers were blinded to all clinical data and x-ray diagnosis and rated 3DUS volumes for the presence or absence of fracture, fracture characteristics when present, and additional findings. Agreement between novices and experts in 3DUS interpretation and between 3DUS and x-ray findings are reported (kappa/ICC). Sensitivity/specificity/LR+/LR- with 95% CI were calculated. Time to perform and interpret 3DUS were reported. Results: 22 subjects were enrolled before the study was suspended due to the COVID-19 pandemic, with 90 3DUS volumes available for interpretation. Analysis is ongoing as results continue to be submitted, precluding calculation of kappa/ICC at this time. Expert 1 had sensitivity 0.8 (0.28, 0.99), specificity 0.69 (0.39, 0.91), LR+ 2.58 (1.03, 6.49), and LR- 0.29 (0.05, 1.73). Novice 1 had sensitivity 0.4 (0.05, 0.85), specificity 0.31 (0.09, 0.61), LR+ 0.58 (0.19, 1.79), and LR- 1.94 (0.66, 5.70). Interpretation times declined by over 50% for both novice and expert readers with an increasing number of scans interpreted. Mean acquisition time was 97 seconds per volume (median 97, IQR 57.75) with a mean of 2.5 volumes acquired per subject (median 2, IQR 1.25). Conclusion: Novice-acquired 3DUS by augmentation of 2DUS was rapid, and interpretation times decreased rapidly with experience. Preliminary results show a promising LR+ when scans are interpreted by an expert reader.
RESUMO
Study Objectives: Carotid ultrasound using dedicated 3D systems is more reproducible and better quantifies disease compared to 2D Doppler ultrasound, but 3D system costs limit access. Low-cost point-of-care 3D ultrasound (POC 3DUS) can augment any 2D ultrasound. This system previously had near-perfect agreement for fetal measurements between novice and expert operators. We hypothesized that carotid assessment would not differ between novice-acquired 3DUS interpreted by novices and experts and CT angiography (CTA) interpreted by radiologists. Methods: We adhered to STARD criteria. Enrollment was by prospective convenience sample at a single medical center;any patient with recent/upcoming head and neck CTA was eligible. 2D B mode US acquisitions used a linear probe coupled to a screen capture device or smartphone, plus an orientation sensor and 3D reconstruction software. Scans were displayed as 2D stacks and intersecting cardinal planes (Figure). 3DUS were interpreted by medical students (novice), US fellowship trained emergency physicians, and radiologists (expert). CTAs were interpreted by neuroradiologists. Readers described NASCET stenosis, plaque, intimal-medial thickness, and minimum luminal cross-sectional area. Inter-reader reliability was measured by intraclass correlation coefficient (ICC)/kappa. We determined a sample size of 50 subjects for ICC 0.7 (alpha 0.05, power 0.8) and kappa 0.8. 3DUS sensitivity/specificity/LRs were estimated with CTA as the reference standard. Anonymous patient satisfaction surveys were administered. Results: Due to COVID-19, enrollment ended after 30 subjects (144 3DUS, 33 CTAs). Of the 60 arteries imaged, 21 had plaque on clinical CTA interpretation. Analysis is still in process. Mean 3DUS acquisition and reconstruction times were 13.1 sec (median 12.7, IQR 9.1-17.3) and 7.9 sec (med 8.0, IQR 5.0-10.3). Mean 3DUS interpretation time was 3m, 52s (med 3:06, IQR 2:14-4:49) for the first 497 3DUS reads. 13 patient surveys were completed. Mean subject willingness to repeat 3DUS was 8.1/10 (med 10, IQR 6.1-10). 2 subjects reported increased discomfort during the exam (mean change 0, med 0, IQR 0-0). 9 of 11 (81.8%) perceived a shorter scan time for 3DUS than for CTA, MRA, and/or 2DUS (2 declined to answer). CTA inter-reader agreement on plaque presence is 11/14 (0.79, 95% CI 0.52-0.92). Expert interpretations of the first 120 3DUS agreed on 55 (0.45, 95% CI 0.37-0.55), disagreed on 35 (0.29, 95% CI 0.22-0.38), and one or both readers were “unsure” on 30 (0.25, 95% CI 0.18-0.33). Of 90 3DUS where both readers answered with certainty, there was 61% raw agreement (95% CI 0.51-0.71). For the first 264 expert 3DUS interpretations, sensitivity is 0.77 (95% CI 0.66-0.87), specificity 0.59 (95% CI 0.50-0.67), +LR 0.47, -LR 0.84, using the original CTA read as reference standard (excluding 42 “unsure”). Conclusion: POC 3DUS is time-efficient with good patient satisfaction and promising sensitivity. Potential applications include initial diagnostic evaluation for neurologic symptoms or carotid bruit in low-resource settings. [Formula presented]