6 - First-pass multi-contrast and multi-phase myocardial perfusion using simultaneous multi-slice imaging

Wednesday, February 12, 2020

4:17 PM – 4:26 PM

Location: Canary 3 & 4

Background: Conventional myocardial perfusion protocols use a short saturation delay time (TS) to enable acquisition of multiples slices (usually 3-4) in each heartbeat. However, there may be benefits of using longer TS to reduce the blood/myocardium (BM) signal ratio associated with dark rim artifacts, and to increase the myocardial/defect (MD) contrast, potentially leading to improved visual detection of perfusion defects. Simultaneous multislice (SMS) imaging allows to acquire multiple slices using the same time as a single-slice acquisition (1) and has proven promising to accelerate myocardial perfusion (2). In this study, we develop a multi-TS/multi-phase myocardial perfusion SMS sequence to increase MD contrast and to reduce BM ratio.

Methods: The proposed sequence consists of two saturation recovery blocks (#1/#2) acquired in each heartbeat. Each block uses a different TS (#1: LTS=300ms; #2: STS=130ms). Three slices (base, mid, apex) are simultaneously imaged using SMS with multiband factor (MB) 3. SMS was performed using CAIPIRINHA encoding (3) (relative shift of the slices of FOV/3 along PE direction) adapted for bSSFP imaging (4) and combined with GC LOLA (5). T-GRAPPA acceleration (6) and phase oversampling were employed for an in-plane acceleration of 2.3. Image reconstruction was performed using a non-linear iterative reconstruction algorithm with spatio/temporal L1 regularisation (7).
Numerical simulations were used to study the impact of TS for MD contrast and BM ratio (Fig1). The sequence was evaluated in 5 patients referred for contrast CMR (acquisition parameters in Fig2) at 1.5T (MAGNETOM Aera, Siemens Healthcare, Erlangen, Germany). Each patient underwent late gadolinium enhancement (LGE) imaging (one patient LGE positive). A contrast dose of 0.075 (4 cases)/0.150 (1 case) mmol/kg was injected. Patients performed an exhale breathold during first pass perfusion. LTS and STS data were compared as follows: blood pool and left ventricular myocardium were segmented at baseline, peak blood, and peak myocardial enhancement. Contrast between peak and baseline myocardium (used as a surrogate for defect) is reported. BM ratios at peak blood and peak myocardium were calculated.

Results: Simulations showed that MD contrast is maximized for a TS range of 300-500ms (Fig1a). Fig1b suggests that the BM ratio decreases with increasing TS. Across all patients, LTS images led to higher peak vs baseline myocardium contrast (158±21%, p< 0.01) as well as decreased BM ratio at peak blood (62±13%) and peak myocardium (79±12%) (Fig2b/c/d). In the LGE-positive patient (Fig3), myocardial/scar contrast increased by 158% at peak myocardial enhancement.

Conclusion: SMS enables multi-TS and multi-phase myocardial perfusion imaging. Long TS images result in increased myocardial/defect contrast and decreased peak blood/myocardium signal ratios. Further studies in a larger patient population are warranted to evaluate the benefit of this technique.

Presenting Author(s)

GF

Giulio Ferrazzi, PhD

Research Associate
King's College London

Disclosure: Disclosure information not submitted.

Primary Author(s)

GF

Giulio Ferrazzi, PhD

Research Associate
King's College London

Disclosure: Disclosure information not submitted.

Co-Author(s)

Sarah McElroy, MSc

PhD Student
King's College London

Disclosure: Disclosure information not submitted.
RN

Radhouene Neji, PhD

Senior MR Scientist
Siemens Healthineers

Disclosure: Disclosure information not submitted.
KK

Karl Kunze, PhD

Siemens Healthineers

Disclosure: Disclosure information not submitted.
Muhummad Sohaib Nazir, MD, PhD

NIHR Clinical Lecturer in Cardiology
King's College London

Disclosure: Disclosure information not submitted.
PS

Peter Speier, PhD

Principal Key Expert
Siemens Healthcare GmbH

Disclosure: Siemens Healthcare GmbH (Individual(s) Involved: Self, Products/Services: MR products): Other Financial or Material Support, Salary, patent royalties, Stockholder/Ownership Interest (excluding diversified mutual funds)
DS

Daniel Stäb, PhD

Siemens Healthineers

Disclosure: Disclosure information not submitted.
CF

Christoph Forman, PhD

Siemens Healthcare GmbH, Erlangen, Germany
Siemens Healthcare GmbH

Disclosure: Disclosure information not submitted.
Reza Razavi, PhD

Professor of Paediatric Cardiovascular Science
King's College London

Disclosure: Disclosure information not submitted.
Amedeo Chiribiri, MD, PhD, FSCMR

Reader in Cardiovascular Imaging; Consultant Cardiologist
King's College London

Disclosure: GE Healthcare: Consulting Fees (e.g., advisory boards); Philips Healthcare: Grant/Research Support; Siemens Healthineers: Grant/Research Support
SR

Sébastien Roujol, PhD

Lecturer, Biomedical Engineering Department
King's College London

Disclosure: Disclosure information not submitted.