Discussion
pulmonary embolism, sub-collectives, MM
PULMONARY EMBOLISM
This prospective study showed that the performance of the device-assisted Mueller maneuver (MM) compared to the standard breathing command (SBC) did in tendency increase contrast attenuation in the pulmonary trunk in CTPA studies. Furthermore, the presence of the TIC phenomenon was reduced significantly to 0% in this single-center study, and using the device resulted in a better overall contrast on the central, lobar, segmental, and subsegmental levels. As a result, an increase in diagnostic accuracy in patients with suspected pulmonary embolism might be feasible by device-assisted Mueller maneuver.Given that the rate of TIC phenomenon was significantly lower in the MM group, lower blood flow from the IVC [The concern of suboptimal contrast has been discussed since the implementation of CTPA in clinical routine, as it poses a relevant clinical challenge. Therefore, the influence of different breathing techniques during CTPA scanning was investigated in several studies. Gosselin et al found the TIC phenomenon as an inspiration-associated artifact in CTPA in 37.2% of patients enrolled [The results of our study presented in this paper are in line with the MR- and CTPA-pilot studies mentioned above and support the assumption that Mueller-Maneuver assisted by an appropriate device can increase contrast attenuation in CTPA and reduce the presence of TIC phenomenon. The clinical importance of this finding is supported by evidence showing that the TIC phenomenon is present in every fifth patient using standard end-inspiratory breath-hold command [The results presented in this work must be interpreted with regard to certain limitations: Blinding the readers for the presence or absence of the breathing device was not fully feasible, due to a variation in arm positioning and visibility in the topogram. Certain device-associated artifacts may be possible: In this study, breathing artifacts did differ significantly between MM and SBC groups for the collective. Yet, this may be addressed by techniques, which do not require the device to be held in the hand. Furthermore, the applicability of the device may differ based on the patient’s condition. However, in this study, the device was applied to a diverse collective of patients in a university medical center emergency setting. Additional studies on sub-collectives or in different clinical settings may be of interest.In summary, this work shows the advantages of a device-assisted, suction against resistance breathing maneuver (Mueller maneuver) in CTPA studies with regard to diagnostic image quality and, especially, mitigation of the TIC phenomenon in a prospective study. Implementation of an appropriate device in PE diagnostics with CTPA may be a feasible strategy to improve diagnostic accuracy and lower the risk of missed PE.