Chest x-ray (CXR) can play a role in diagnosing patients with suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but only few small-scale studies are available. We assessed the diagnostic performance of CXR in consecutive patients presenting at the emergency room at the Policlinico San Donato, Milan, Italy from February 24 to April 8, 2020 for suspected SARS-CoV-2 infection. The results of CXR were classified as positive or negative according to the original prospective radiologic reports. To overcome the limitations of reverse transcriptase-polymerase chain reaction (RT-PCR) swab, especially oscillating sensitivity, we added the information obtained from phone calls to discharged patients with negative initial RT-PCR. Thus, we included 535 patients with concomitant CXR and RT-PCR on admission (aged 65±17 y; 340 males, 195 females), resulting in 408 RT-PCR positive and 127 negative patients at the composite reference standard. Original CXR reports showed an 89.0% sensitivity (95% confidence intervals [CI], 85.5%-91.8%), 60.6% specificity (95% CI, 51.6%-69.2%), 87.9% positive predictive value (95% CI, 84.4%-90.9%), and 63.1% negative predictive value (95% CI, 53.9%-71.7%). The adoption of CXR alongside RT-PCR to triage patients with suspected SARS-CoV-2 infection could foster a safe and efficient workflow, counteracting possible false negative RT-PCR results.
Highlights
Chest x-ray had a 89 % sensitivity detecting COVID-19 pneumonia during pandemic peak.
Experienced radiologists had higher specificity than less-experienced ones.
Overall and per-group sensitivity in detecting COVID-19 pneumonia increased over time.
Overall and per-group accuracy in detecting COVID-19 pneumonia increased over time.
BackgroundThe contrast agent (CA) dose for abdominal computed tomography (CT) is typically based on patient total body weight (TBW), ignoring adipose tissue distribution. We report on our experience of dosing according to the lean body weight (LBW).MethodsAfter Ethics Committee approval, we retrospectively screened 219 consecutive patients, 18 being excluded for not matching the inclusion criteria. Thus, 201 were analysed (106 males), all undergoing a contrast-enhanced abdominal CT with iopamidol (370 mgI/mL) or iomeprol (400 mgI/mL). LBW was estimated using validated formulas. Liver contrast-enhancement (CEL) was measured. Data were reported as mean ± standard deviation. Pearson correlation coefficient, ANOVA, and the Levene test were used.ResultsMean age was 66 ± 13 years, TBW 72 ± 15 kg, LBW 53 ± 11 kg, and LBW/TBW ratio 74 ± 8%; body mass index was 26 ± 5 kg/m2, with 9 underweight patients (4%), 82 normal weight (41%), 76 overweight (38%), and 34 obese (17%). The administered CA dose was 0.46 ± 0.06 gI/kg of TBW, corresponding to 0.63 ± 0.09 gI/kg of LBW. A negative correlation was found between TBW and CA dose (r = -0.683, p < 0.001). CEL (Hounsfield units) was 51 ± 18 in underweight patients, 44 ± 8 in normal weight, 42 ± 9 in overweight, and 40 ± 6 in obese, with a significant difference for both mean (p = 0.004) and variance (p < 0.001). A low but significant positive correlation was found between CEL and CA dose in gI per TBW (r = 0.371, p < 0.001) or per LBW (r = 0.333, p < 0.001).ConclusionsThe injected CA dose was highly variable, with obese patients receiving a lower dose than underweight patients, as a radiologist-driven ‘compensation effect’. Diagnostic abdomen CT examinations may be obtained using 0.63 gI/kg of LBW.
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