Pamplemousse: a fast and one-click sequence combining co-registered PSIR, dual bright- and black-blood LGE, and T2 mapping for efficient and comprehensive assessment of myocardial injury

Presenting Author(s)

• 

  Thaïs Genisson, MSc

  PhD student
  IHU Liryc, Université de Bordeaux
  Bordeaux, Aquitaine, France

Primary Author(s)

• 

  Thaïs Genisson, MSc

  PhD student
  IHU Liryc, Université de Bordeaux
  Bordeaux, Aquitaine, France

Co-Author(s)

• 

  Kalvin Narceau, MSc

  Phd student
  Bordeaux University - INSERM U1045
  Pessac, Aquitaine, France
• TR

  Théo Richard, MSc

  Engineer
  IHU LIRYC, Heart rhythm disease institute, Université de Bordeaux – INSERM U1045, Avenue du Haut Lévêque, 33604, Pessac, France
  Bordeaux, Aquitaine, France
• 

  Victor de Villedon de Naide, MSc

  PhD student
  Bordeaux University - INSERM U1045
  Bordeaux, Aquitaine, France
• EB

  Ewan Barel

  Research engineer
  IHU Liryc, Université de Bordeaux, France
• EG

  Edouard Gerbaud, MD, PhD

  Cardiac Intensive Care Unit, Groupe Hospitalier Sud, CHU de Bordeaux, Pessac, France, France
• PJ

  Pierre Jaïs, MD, PhD

  PROF/PhD
  Hôpital Cardiologique du Haut-Lévêque, CHU de Bordeaux
  Bordeaux, Aquitaine, France
• MS

  Matthias Stuber, PhD

  Professor/Director
  CIBM/CHUV/UNIL
  Lausanne, Switzerland
• HC

  Hubert Cochet, MD, PhD

  Professor
  Bordeaux University - INSERM U1045
  Bordeaux, Aquitaine, France
• 

  Aurelien Bustin, FSCMR

  Research Associate
  Department of Cardiovascular Imaging, Hôpital Cardiologique du Haut-Lévêque, CHU de Bordeaux, Avenue de Magellan, Pessac, France; IHU LIRYC, Electrophysiology and Heart Modeling Institute, Université de Bordeaux – INSERM U1045, Avenue du Haut Lévêque, Pessac, France; Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
  Bordeaux, Aquitaine, France

Background: CMR relies on multiple sequences to assess myocardial injury: T2 mapping, phase-sensitive inversion recovery (PSIR)¹ and more recently, black-blood (BlB) imaging^2,3. These sequences are run independently, increasing exam complexity: patients face longer exams with many breath-holds; MR operators handle complex planning/execution; radiologists perform repetitive analyses as images are not co-registered and contrast may be suboptimal^2,3.

We introduce and evaluate the feasibility of a novel “one-click” sequence, called Pamplemousse, acquiring co-registered PSIR magnitude and phase, bright-blood (BrB) and BlB images, and T2 maps⁴^˒⁵.

Methods: The study included 10 patients (80% male, age range 42-79) with chronic ischemic heart disease. Breath-held short-axis 2D whole-heart post-contrast Pamplemousse images were collected on a 1.5T system (Siemens Aera). Image resolution was 1.4x1.4mm² with 8mm slice thickness. For each slice location, 12 interleaved single-shot images (3 PSIR magnitude, 3 PSIR reference, 3 BrB and 3 BlB) were acquired in mid-diastole. A non-selective inversion pulse directly followed by an adiabatic T2-preparation module generated BlB contrast. T2-preparation module alone, with incremental times (0, 27, 55 ms), generated BrB contrast and enabled co-registered T2 mapping using 2-parameter fitting (Fig. 1). Conventional breath-held PSIR¹, joint BrB/BlB (SPOT⁵) images and pre-contrast T2 maps were also acquired with similar parameters.

Acquisition times were estimated for 10 slices, assuming one breath-hold per slice, 10s breathing recovery pause and 60bpm heart rate. Left ventricular (LV) wall was manually outlined on conventional PSIR, SPOT BrB and Pamplemousse BrB images; averaged segmentation times on the later were recorded. Manual scar segmentation was done on PSIR (conventional and Pamplemousse) and BlB (SPOT and Pamplemousse) images. Scar burden agreement for PSIR and BlB images was assessed with Bland–Altman analysis and intraclass correlation coefficient (ICC). Remote T2 values were measured on conventional and Pamplemousse maps.

Results: Estimated acquisition times were: PSIR 3min10s, SPOT 3min10s, T2 mapping 2min40s (9min total) vs. Pamplemousse 3min30s. LV wall segmentation on Pamplemousse BrB images averaged 13min31s. As all Pamplemousse images are co-registered, contours can be propagated onto PSIR and T2 maps, saving ~27min in segmentation time (Fig.2). Excellent agreement in scar burden was found between conventional and Pamplemousse PSIR (bias -0.4±11.2%/ICC=0.89, Fig.3A) and SPOT and Pamplemousse BlB (bias +4.2±9.2%/ICC=0.93, Fig.3B). Remote T2 values accuracy/precision were 48.9±2.0/3.2±0.5ms for conventional and 60.8±3.8/5.0±1.3ms for Pamplemousse (Fig.3C).

Conclusion: This work introduces a time-saving “one-click” cardiac imaging sequence for comprehensive assessment of myocardial injuries. Further study in a larger cohort with several different cardiomyopathies, including acute myocardial infarction, is warranted.

Fig.1: Schematic overview of the proposed Pamplemousse sequence (breath-held co-registered PSIR, bright-blood, black-blood, and T2 mapping sequence). During the first heartbeat, a 180° inversion pulse is applied followed by a magnetization recovery heartbeat (PSIR sequence). The first two heartbeat allows the reconstruction of the PSIR magnitude and phase images. During the third heartbeat, a 180° inversion pulse is followed by an adiabatic T2 preparation module, generating a black-blood contrast ideal for scar detection. In the fourth heartbeat, only the T2 module is activated, resulting in bright-blood contrast tailored for scar localization. To acquire one slice, the latter sequence of 4 heartbeats is repeated 3 times. The preparation time for the T2 module is progressively increased across the 3 bright-blood shots ([0, 27, 55] ms), allowing for the extraction of a T2 map through curve fitting. Imaging parameters included: 5 signal averages, 1.4mmx1.4mm in-plane resolution, 8mm slice thickness, FA=60° (FA PSIR reference=8°), GRAPPA x2, ~160ms acquisition window, TE/TR=1.2/2.8ms, bandwidth=870Hz/pixel, inversion time determined from a prior scout acquisition. Abbreviations: FA = flip angle; TI = inversion time.
Fig.2: A) Comparison of conventional (PSIR, SPOT bright- and black-blood, T2 mapping) and Pamplemousse images for three patients with ischemic heart disease. B) Full ventricular view of Pamplemousse images in a 42-year-old-male patient with myocardial infarction originating from left anterior descending artery.
Fig.3: A) Bland-Altman analysis for scar burden comparing conventional and Pamplemousse PSIR images. B) Bland-Altman analysis for scar burden comparing SPOT and Pamplemousse black-blood images. C) Accuracy and precision of remote T2 values for both conventional and Pamplemousse T2 maps. Two patients with unusable conventional T2 maps were excluded.