Decreased Noise and Identification of Very Low Voltage Signals Using a Novel Electrophysiology Recording System.

Aims: The interpretation of intracardiac electrograms recorded from conventional electrophysiology recording systems is frequently impacted by powerline (50/60 Hz) noise and distortion due to notch filtering. This study compares unipolar electrograms recorded simultaneously from a conventional electrophysiology recording system and one of two 3D mapping systems (control system) with those from a novel system (ECGenius, CathVision ApS) designed to reduce noise without the need for conventional filtering. Methods: Unipolar electrograms were recorded simultaneously from nine consecutive patients undergoing catheter ablation for AF (five patients), atrioventricular nodal re-entrant tachycardia (three patients), or ventricular tachycardia (one patient) over the course of 1 week in 2020. Results: The noise spectral power of the novel system (49-51 Hz) was 6.1 ± 6.2 times lower than that of the control system. Saturation artefact following pacing (duration 97 ± 85 ms) occurred in eight control recordings and no novel system recordings (p<0.001). High frequency, low amplitude signals and fractionated electrograms apparent on unfiltered novel system unipolar recordings were not present on control recordings. Control system notch filtering obscured His bundle electrograms observable without such filtering using the novel system and induced electrogram distortion that was not present on novel system recordings. Signal saturation occurred in five of seven control system recordings but none of the novel system recordings. Conclusion: In this study, novel system recordings exhibited less noise and fewer signal artefacts than the conventional control system and did not require notch filtering that distorted electrograms on control recordings. The novel recording system provided superior electrogram data not apparent with conventional systems.

Brain perfusion CT compared with ¹5O-H2O PET in patients with primary brain tumours.

PURPOSE: Perfusion CT (PCT) measurements of regional cerebral blood flow (rCBF) have been proposed as a fast and easy method for identifying angiogenically active tumours. In this study, quantitative PCT rCBF measurements in patients with brain tumours were compared to the gold standard PET rCBF with (15)O-labelled water ((15)O-H(2)O). METHODS: On the same day within a few hours, rCBF was measured in ten adult patients with treatment-naïve primary brain tumours, twice using (15)O-H(2)O PET and once with PCT performed over the central part of the tumour. Matching rCBF values in tumour and contralateral healthy regions of interest were compared. RESULTS: PCT overestimated intratumoural blood flow in all patients with volume-weighted mean rCBF values of 28.2 ± 18.8 ml min(-1) 100 ml(-1) for PET and 78.9 ± 41.8 ml min(-1) 100 ml(-1) for PCT. There was a significant method by tumour grade interaction with a significant tumour grade rCBF difference for PCT of 32.9 ± 15.8 ml min(-1) 100 ml(-1) for low-grade (WHO I + II) and 81.5 ± 15.4 ml min(-1) 100 ml(-1) for high-grade (WHO III + IV) tumours, but not for PET. The rCBF PCT and PET correlation was only significant within tumours in two patients. CONCLUSION: Although intratumoural blood flow measured by PCT may add valuable information on tumour grade, the method cannot substitute quantitative measurements of blood flow by PET and (15)O-H(2)O PET in brain tumours.

Brain perfusion CT compared with15O-H2O-PET in healthy subjects.

BACKGROUND: Regional cerebral blood flow [rCBF] measurements are valuable for identifying angiogenically active tumours, and perfusion computed tomography [CT] has been suggested for that purpose. This study aimed to validate rCBF measurements by perfusion CT with positron-emission tomography [PET] and15O-labelled water [15O-H2O] in healthy subjects. METHODS: RCBF was measured twice in 12 healthy subjects with15O-H2O PET and once with perfusion CT performed over the basal ganglia. Matching rCBF values in regions of interest were compared. RESULTS: Measured with perfusion CT, rCBF was significantly and systematically overestimated. White matter rCBF values were 17.4 ± 2.0 (mean ± SD) mL min-1 100 g-1 for PET and 21.8 ± 3.4 mL min-1 100 g-1 for perfusion CT. Grey matter rCBF values were 48.7 ± 5.0 mL min-1 100 g-1 for PET and 71.8 ± 8.0 mL min-1 100 g-1 for perfusion CT. The overestimation of grey matter rCBF could be reduced from 47% to 20% after normalization to white matter rCBF, but the difference was still significant. CONCLUSION: RCBF measured with perfusion CT does contain perfusion information, but neither quantitative nor relative values can substitute rCBF measured by15O-H2O PET yet. This, however, does not necessarily preclude a useful role in patient management.