Initial evaluation of prospective cardiac triggering using photoplethysmography signals recorded with a video camera compared to pulse oximetry and electrocardiography at 7T MRI

Table 1 Noise properties from videos recorded during the measurement protocol

Result	Noise	1/(1)	1/(2)	1/(3)	2/(1)	2/(2)	2/(3)	3/(1)	3/(2)	3/(3)
vPPG signal computed from video of subject/stage
SNR (dB)	VLF	−9.3838	−11.1829	−7.4733	−9.1363	−15.2723	−15.5896	−15.8005	−8.2305	−7.8545
	LF	−4.1574	−9.5661	−9.0184	−0.6905	−1.1406	−0.0327	−6.3080	−4.4844	−7.4882
	HF	8.8457	6.0230	5.6720	7.0804	3.8714	5.1022	4.4189	4.4099	3.4681
Estimated \(\mu\)	VLF	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
	LF	0.0004	−0.0005	0.0039	0.0012	0.0004	0.0002	−0.0011	0.0007	0.0010
	HF	0.0001	0.0001	−0.0001	0.0000	0.0001	0.0000	0.0002	0.0002	0.0001
Estimated \(\sigma\)	VLF	0.1288	0.1201	0.0994	0.1251	0.2056	0.1344	0.1644	0.1126	0.0719
	LF	0.0399	0.0598	0.0709	0.0259	0.0214	0.0128	0.0313	0.0418	0.0382
	HF	0.0081	0.0092	0.0120	0.0105	0.0121	0.0068	0.0087	0.0142	0.0111
KS test	VLF	1	1	1	1	1	1	1	1	1
	LF	1	1	1	1	1	1	1	1	0
	HF	1	0	0	0	0	0	0	0	1

		4/(1)	4/(2)	4/(3)	5/(1)	5/(2)	5/(3)	6/(1)	6/(2)	6/(3)
SNR (dB)	VLF	−16.6716	−21.0377	−7.7598	−19.9921	−15.5100	−13.4868	−5.6413	−7.2446	−19.7351
	LF	−2.7974	−4.1851	−3.1127	−7.6886	−5.3285	−6.5990	0.7468	0.9326	−5.9409
	HF	7.7905	5.0893	4.8462	6.2689	7.5451	7.3158	9.0495	8.1937	6.0176
Estimated \(\mu\)	VLF	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
	LF	−0.0003	−0.0002	0.0004	−0.0003	−0.0002	0.0011	0.0008	−0.0000	−0.0001
	HF	0.0001	0.0004	0.0009	0.0001	−0.0000	0.0000	0.0000	−0.0001	−0.0000
Estimated \(\sigma\)	VLF	0.2149	0.2689	0.1253	0.2048	0.1579	0.1702	0.1257	0.1356	0.2005
	LF	0.0203	0.0198	0.0419	0.0260	0.0277	0.0449	0.0343	0.0307	0.0163
	HF	0.0063	0.0072	0.0165	0.0044	0.0058	0.0083	0.0123	0.0127	0.0049
KS test	VLF	1	1	1	1	1	1	1	1	1
	LF	1	1	1	1	0	1	1	1	1
	HF	1	1	1	1	1	0	1	0	0

		7/(1)	7/(2)	7/(3)	8/(1)	8/(2)	8/(3)
SNR (dB)	VLF	−5.7181	−11.7821	−6.2986	−4.8782	−9.8592	−8.6507
	LF	0.4626	−0.9377	2.5547	−1.0125	−1.0125	−4.1720
	HF	9.0742	7.0814	7.1712	7.3655	6.2019	6.2604
Estimated \(\mu\)	VLF	0.0000	0.0000	0.0000	0.0000	0.0000	0.0000
	LF	0.0008	0.0001	−0.0009	0.0019	0.0019	0.0014
	HF	0.0001	0.0003	0.0005	0.0002	0.0001	0.0002
Estimated \(\sigma\)	VLF	0.1200	0.1910	0.1481	0.1077	0.1284	0.1047
	LF	0.0329	0.0299	0.0306	0.0398	0.0491	0.0369
	HF	0.0116	0.0123	0.0179	0.0141	0.0109	0.0102
KS test	VLF	1	1	1	1	1	1
	LF	0	1	1	1	1	1
	HF	1	1	1	1	0	0

All values are rounded to the fourth decimal place. \(\mu\) and \(\sigma\) are obtained by either fitting the logistic distribution (Eq. 13) to histograms of the \(f(t)_{LF}\) and \(f(t)_{HF}\) noise or fitting the normal distribution (Eq. 14) to histograms of \(f(t)_{VLF}\) . The result of the KS test is 1 if the test rejects the null hypothesis at \(\alpha =1\%\) and 0 otherwise

ISSN: 1475-925X