A RANDOMIZED TRIAL OF SPIRAL CT AND VENTILATION-PERFUSION SCINTIGRAPHY FOR THE DIAGNOSIS OF PULMONARY-EMBOLISM

Purpose: To compare spiral computed tomographic pulmonary angiography (SCTA) with lung ventilation-perfusion scintigraphy (VQS) as the initi al investigation of patients with suspected pulmonary embolism (PE). M aterials and Methods: Prospective randomized trial of 78 patients with suspected pulmonary embolism. Patients underwent either SCTA or lung VQS as their initial investigation for PE, Cross-over between groups m eant that 50 patients received both examinations, The clinicians' asse ssment of overall clinical likelihood of PE was also collected. Result s: (1) It was possible to make a confident diagnosis in a significantl y larger proportion of patients when SCTA was used as the initial inve stigation (35/39, 90%) compared with using VQS first (21/39, 54% P < 0 .001). The main difference between the two groups was that SCTA demons trated lesions other than pulmonary embolism considered responsible fo r the patients' symptoms in 13/39 patients (33%) randomized to SCTA as the initial investigation and following a non-diagnostic VQS in 10/39 patients (25%) randomized to VQS as the initial investigation. (2) Th ere was no difference in the prevalence or detection of PE in the two groups. SCTA demonstrated pulmonary emboli in 6/39 patients (16%) in t he SCTA first group and VQS was high probability for PE in 5/39 patien ts (13%) in the VQS first group, SCTA detected PE in a further two pat ients in the VQS first group. Conclusion: It is proposed that, where l ogistically feasible, SCTA should replace VQS as the initial investiga tion for PE in patients with an underlying cardio-respiratory disorder .