Dual Energy Gemstone Spectral Imaging (GSI) lung perfusion MDCT in acute pulmonary embolism: blood volume assessment and correlation with clinical symptoms

Abstract

Objectives: Aim of the study is to report feasibility and usefulness of single tube Dual Energy Spectral CT with rapid kVp switching imaging as surrogate of perfusion to evaluate the changes of pulmonary blood flow in symptomatic patients with suspected pulmonary embolism (PE) as support to conventional CT Pulmonary Angiography (CTPA) Materials and Methods: CTPA was performed in 86 consecutive patients (36 male, mean age: 74.8±10.9 y) with suspected PE (64- slice Discovery CT 750HD, GE) using Dual Energy Gemston Spectral Imaging (GSI). Dual Energy images were processed at workstation with MD review Spectral imaging software (Iodine-water) CTPA images and GSI iodine maps were assessed for presence of PE and iodine contrast. The image quality was evaluated using a semiquantitative score (0: no artifacts, 1: minimal artifacts, 2: substantial artifacts, 3: not evaluable). CTPA and GSI images were compared and related to clinical symptoms of patients Results: CTPA detected PE in 33 out of 86 pts. Perfusion defects were detected in 111 out of 1548 lung segments. Mean image quality score was 1.4±0.8 In comparison to CT angiography GSI showed in a patient based model sensibility, specificity, negative predictive value, positive predictive value and accuracy of: 73.3%, 87.5%, 85.9%, 75.8%, 82.5% respectively, while in a segment based model sensibility, specificity, negative predictive value, positive predictive value and accuracy were respectively 48.9%, 96.4%, 91.6%, 70.2% and 89.4% In comparison with CTPA, all patients classified as positive on GSI iodine maps were symptomatics for dyspnea Conclusions: Dual Energy GSI lung perfusion imaging is feasible and is a valid support to conventional CT angiography to assess presence of PE, specially in symptomatics patients that could have small vessels clots not detectable with standard images only.