Multi Slice Spiral CT Pulmonary Angiography in Dynamic Pitch Mode using Volume Helical Shuttle Technology for the Diagnosis of Pulmonary Embolism

ABSTRACT

Introduction: Multi slice Computed Tomography Pulmonary Angiography (CTPA) in dynamic pitch (Volume Helical Shuttle-VHS) mode is an evolving method to visualize pulmonary arteries including the peripheral pulmonary vasculature. The purpose of this study is to evaluate CT Pulmonary Angiography in dynamic pitch mode (Volume Helical Shuttle) for pulmonary embolism in comparison with standard pitch mode. Methods: We have done a multicentric analytical comparison study with study group involving patients undergone CTPA in dynamic pitch mode-Volume Helical Shuttle (VHS) and comparison group involving patients undergone CTPA in standard pitch mode. Results: Optimal contrast enhancement phase of the pulmonary artery in the study group in Phase I to III were 22.6%, 43.4% and 34%. The best phases were the last two phases in our study. Study Group main pulmonary artery mean signal intensity is 423.83±75.94 HU and comparison groups mean signal intensity is 361.74±98.28HU (P value = 0.039). The percentages of analyzable segmental arteries were 91.6% in study group and 87.3% in comparison group (P value-0.008). The percentages of analyzable sub segmental arteries were 89.5% in study group and 84% in comparison group (P value-0.004). The study group shows less percentage of motion artefacts and higher image quality than the comparison group, however it was not statistically significant (P value >0.05). Conclusions: Multislice CTPA in dynamic pitch mode using Volume Helical Shuttle (VHS) technology increase the ability to obtain the Optimal contrast enhancement in pulmonary arteries, improves the overall image quality, obviate the need for breath holding.