Real-Time Phase-Contrast MRI to Monitor Cervical Blood and Cerebrospinal Fluid Flow Beat-by-Beat Variability

Baselli, Giuseppe; Fasani, Federica; Pelizzari, Laura; Cazzoli, Marta; Baglio, Francesca; Laganà, Maria Marcella

doi:10.3390/bios12060417

Cited by 14 publications

(18 citation statements)

References 39 publications

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“…Additional file 3 : Figure S3 shows a representative pulse wave (separately for ICAs, IJVs, and CSF flow rates): the diastolic peaks were identified over the whole 60-s acquisition and aligned, each heart cycle dynamic was stretched or compressed, normalizing each cardiac cycle duration to the mean HR as previously described in [ 32 ], and finally the median, 5th and 95th percentiles of all the curves were computed.…”

Section: Resultsmentioning

confidence: 99%

Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters

Laganà

Tella

Ferrari

et al. 2022

Fluids Barriers CNS

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Background Cervical blood and cerebrospinal fluid (CSF) flow rates can be quantified with Phase-contrast (PC) MRI, which is routinely used for clinical studies. Previous MRI studies showed that venous and CSF flow alterations are linked to various pathological conditions. Since it is well known that, besides the heart beating, the thoracic pump influences the blood and CSF dynamics, we studied the effect of different respiration modes on blood and CSF flow rates using a real-time (RT)-PC prototype. Methods Thirty healthy volunteers were examined with a 3 T scanner. A RT-PC sequence was acquired at the first cervical level to quantify the flow rates of internal carotid arteries, internal jugular veins (IJVs) and CSF. Each RT-PC acquisition was repeated three times, while the subjects were asked to breathe in three different ways for 60 s each: freely (F), with a constant rate (PN) and with deep and constant respiration rate (PD). The average flow rates were computed, they were removed from the respective signals and integrated in the inspiratory and expiratory phases (differential volumes). Finally, the power spectral density was computed for each detrended flow rate. High- and very-high frequency peaks were identified on the spectra while their frequencies were compared to the respiratory and cardiac frequencies estimated using a thoracic belt and a pulse oximeter. The area under the spectra was computed in four 0.5 Hz-wide ranges, centered on the high-frequency peak, on very-high frequency peak and its 2nd and 3rd harmonics, and then they were normalized by the flow rate variance. The effect of breathing patterns on average flow rates, on systolic and diastolic peaks, and on the normalized power was tested. Finally, the differential volumes of inspiration were compared to those of expiration. Results The frequencies of the high- and very-high spectral peaks corresponded to the respiratory and cardiac frequencies. The average flow rate progressively decreased from F to PN to PD breathing, and the cardiac modulations were less predominant especially for the IJVs. The respiratory modulation increased with PD breathing. The average volumes displaced in the inspiratory phases were not significantly different from those of the expiratory one. Conclusions The spectral analyses demonstrated higher respiratory modulations in PD compared to free breathing, even prevailing the cardiac modulation in the IJVs, showing an increment of the thoracic pump affecting the flow rate shape.

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Section: Resultsmentioning

confidence: 99%

Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters

Laganà

Tella

Ferrari

et al. 2022

Fluids Barriers CNS

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“…The scanning protocol for the IJV and SSS flow rate measurements consisted of two separate PC sequences, one with a velocity encoding (VENC) rate of 70 cm/s and the other with a VENC of 40 cm/s, respectively. Both were run using a RT-PC prototype sequence [ 14 , 30 ] with a segmented EPI readout, parallel acceleration factor in the temporal direction, and a 2-sided shared velocity encoding reconstruction algorithm (field of view [FOV] = 153 × 175 mm 2 , matrix size = 96 × 128, interpolated resolution = 0.7 × 0.7 mm 2 , slice thickness = 8.6 mm, time resolution of 58.5 ms, GRAPPA = 3, TR/TE = 14.6/8 ms, flip angle = 15°) [ 14 ]. For IJVs acquisition, the imaging slice was positioned at the C1 vertebra level, perpendicularly to the vessels.…”

Section: Methodsmentioning

confidence: 99%

“…The signal analysis was performed using ad hoc scripts developed in MATLAB (version 2012a, Mathworks, Natick, WA, USA). The physiologic signals were temporally aligned with the RT-PC images, using the starting time stored in the log files recorded during the acquisition and the acquisition time stored in the DICOM headers [ 14 , 31 ], then the average heart rate (HR) and BR during each RT-PC acquisition were computed.…”

Section: Methodsmentioning

confidence: 99%

“…Nonetheless, it does not allow the detection of beat-by-beat flow rate changes and the identification of respiratory influences. The recent advent of a real-time (RT)-PC MRI technique for flow quantification allowed evaluation of the effect of coughing, inspiration, and expiration on the venous flow [ 5 , 10 , 11 ] and beat-by-beat variability [ 14 ]. However, the published studies investigated the blood flow rate of extracranial vessels only, with the exception of work from a preliminary conference proceeding [ 15 ] that showed intracranial maps.…”

Section: Introductionmentioning

confidence: 99%

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Cardiac and Respiratory Influences on Intracranial and Neck Venous Flow, Estimated Using Real-Time Phase-Contrast MRI

et al. 2022

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The study of brain venous drainage has gained attention due to its hypothesized link with various neurological conditions. Intracranial and neck venous flow rate may be estimated using cardiac-gated cine phase-contrast (PC)-MRI. Although previous studies showed that breathing influences the neck’s venous flow, this aspect could not be studied using the conventional segmented PC-MRI since it reconstructs a single cardiac cycle. The advent of real-time PC-MRI has overcome these limitations. Using this technique, we measured the internal jugular veins and superior sagittal sinus flow rates in a group of 16 healthy subjects (12 females, median age of 23 years). Comparing forced-breathing and free-breathing, the average flow rate decreased and the respiratory modulation increased. The flow rate decrement may be due to a vasoreactive response to deep breathing. The respiratory modulation increment is due to the thoracic pump’s greater effect during forced breathing compared to free breathing. These results showed that the breathing mode influences the average blood flow and its pulsations. Since effective drainage is fundamental for brain health, rehabilitative studies might use the current setup to investigate if respiratory exercises positively affect clinical variables and venous drainage.

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“…However, the clinical cardiac-gated cine PC-MRI requires several heartbeats to form the time-resolved flow images covering the entire cardiac cycle, not allowing to assess beat-by-beat variability differences and respiratory-driven flow changes. To overcome these limitations, we recently used a real-time (RT)-PC prototype for the study of blood and CSF flow rate modulations, showing lowfrequency oscillations (Mayer waves) 4 . With the same MRI technique, in the current study we focused on assessing the cardiac and respiratory modulations on the blood and CSF flow rates, and the effects of different respiration modes.…”

Section: Introductionmentioning

confidence: 99%

Measuring respiratory and cardiac influences on blood and cerebrospinal fluid flow with real-time MRI

Laganà

Pirastru

Tella

et al. 2022

Veins and Lymphatics

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Background. A link between various pathological conditions and blood and cerebrospinal fluid (CSF) flow alterations has been suggested by numerous studies.1 The blood and CSF dynamics are influenced by many factors, such as posture,2 heart beating, and thoracic pressure changes during respiration.2,3 The blood/CSF can be estimated using phase-contrast (PC) – magnetic resonance imaging (MRI). However, the clinical cardiac-gated cine PC-MRI requires several heartbeats to form the time-resolved flow images covering the entire cardiac cycle, not allowing to assess beat-by-beat variability differences and respiratory-driven flow changes. To overcome these limitations, we recently used a real-time (RT)-PC prototype for the study of blood and CSF flow rate modulations, showing low-frequency oscillations (Mayer waves).4 With the same MRI technique, in the current study we focused on assessing the cardiac and respiratory modulations on the blood and CSF flow rates, and the effects of different respiration modes. Methods. Thirty healthy volunteers (21 females, median age=26 years old, age range= 19-57 years old) were examined with a 3 T scanner. RT-PC sequences (Figure 1) allowed for a quantification of the flow rates of internal carotid arteries (ICAs), internal jugular veins (IJVs), and CSF at the first cervical level. The superior sagittal sinus (SSS) was also studied in 16 subjects.5 The flow rates were estimated with a temporal resolution of 58.5 ms for the blood, and 94 ms for the CSF. Each RT-PC lasted 60 seconds and was repeated three times: while the subject breathed with free (F) breathing, at a constant rate with a normal (PN) or forced (PD) strength. The systolic, diastolic and average flow rates and their power spectral densities were computed. High and very-high frequency peaks were identified on the spectra. Frequencies associated to the identified peaks were compared to the respiratory and cardiac frequencies estimated by a thoracic band and a pulse oximeter. The area under the spectra, normalized by the flow rate variance, was computed in the respiratory and cardiac frequency ranges (0.5 Hz-wide ranges, centered on the cardiac or breathing frequency peaks, respectively). Results. The frequencies associated with the spectral peaks were not significantly different compared to the respiratory and cardiac frequencies, for all regions and breathing modes. The average blood flow rate and the diastolic CSF peak progressively decreased from F to PN to PD breathing, the flow rate variance remained stable, and only the ICAs cross-sectional area decreased. The respiratory modulation increased with PD breathing compared with F and PN, while the cardiac modulations were less predominant for all the structures of interest. Conclusions. Using the RT-PC sequence we showed that the blood and CSF flow rates were modulated at the respiratory and cardiac frequencies. The observed reduced blood flow rate during forced breathing in the arteries and consequently in the extra and intracranial veins are suggestive of compensatory vasoconstriction in response to decreased CO2 blood concentration. Breathing modulation of flow rates was observed both in the extracranial and intracranial compartments, and it was greater during forced breathing than free breathing, due to the greater thoracic pump effect on the flow rates.

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Real-Time Phase-Contrast MRI to Monitor Cervical Blood and Cerebrospinal Fluid Flow Beat-by-Beat Variability

Cited by 14 publications

References 39 publications

Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters

Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters

Cardiac and Respiratory Influences on Intracranial and Neck Venous Flow, Estimated Using Real-Time Phase-Contrast MRI

Measuring respiratory and cardiac influences on blood and cerebrospinal fluid flow with real-time MRI

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