Rene M Botnar

King's College London | KCL · Division of Imaging Sciences and Biomedical Engineering

The detection and characterization of coronary artery stenosis and atherosclerosis using imaging tools are key for clinical decision-making in patients with known or suspected coronary artery disease (CAD). In this regard, imaging-based quantification can be improved by choosing the most appropriate imaging modality for diagnosis, treatment and pro...

Purpose To develop and evaluate a highly efficient free‐breathing and contrast‐agent‐free three‐dimensional (3D) whole‐heart Cardiac Magnetic Resonance Angiography (CMRA) sequence at 0.55T. Methods Free‐breathing whole‐heart CMRA has been previously proposed at 1.5 and 3T. Direct application of this sequence to 0.55T is not possible due to changes...

Purpose To develop a 3D free‐breathing cardiac multi‐parametric mapping framework that is robust to confounders of respiratory motion, fat, and B1+ inhomogeneities and validate it for joint myocardial T1 and T1ρ mapping at 3T. Methods An electrocardiogram‐triggered sequence with dual‐echo Dixon readout was developed, where nine cardiac cycles were...

Heart failure (HF) affects 64 million people globally with enormous societal and healthcare costs. Myocardial fibrosis, characterised by changes in collagen content drives HF. Despite evidence that collagen type III (COL3) content changes during myocardial fibrosis, in vivo imaging of COL3 has not been achieved. Here, we discovered the first imagin...

Atherosclerosis is a chronic inflammatory condition of the arteries and represents the primary cause of various cardiovascular diseases. Despite ongoing progress, finding effective anti-inflammatory therapeutic strategies for atherosclerosis remains a challenge. Here, we assessed the potential of molecular magnetic resonance imaging (MRI) to visual...

Background Coronary computed tomography angiography (CCTA) is recommended as the first-line diagnostic imaging modality in low-to-intermediate-risk individuals suspected of stable coronary artery disease (CAD). However, CCTA exposes patients to ionizing radiation and potentially nephrotoxic contrast agents. Invasive coronary angiography is the gold...

Background The diagnosis of myocarditis by cardiovascular magnetic resonance (CMR) requires the use of T2 and T1 weighted imaging, ideally incorporating parametric mapping. Current two-dimensional (2D) mapping sequences are acquired sequentially and involve multiple breath-holds resulting in prolonged scan times and anisotropic image resolution. We...

Background Active inflammatory bowel disease (A-IBD) but not remission (R-IBD) has been associated with an increased risk of cardiovascular death and hospitalization for heart failure. Objectives Using cardiovascular magnetic resonance (CMR), this study aims to assess adverse myocardial remodeling in patients with IBD in correlation with disease a...

Purpose To develop a framework for simultaneous three‐dimensional (3D) mapping of T1$$ {\mathrm{T}}_1 $$, T2$$ {\mathrm{T}}_2 $$, and fat signal fraction in the liver at 0.55 T. Methods The proposed sequence acquires four interleaved 3D volumes with a two‐echo Dixon readout. T1$$ {\mathrm{T}}_1 $$ and T2$$ {\mathrm{T}}_2 $$ are encoded into each v...

Cardiovascular magnetic resonance (CMR) imaging is recommended in patients with congenital heart disease (CHD) in clinical practice guidelines as the imaging standard for a large variety of diseases. As CMR is evolving, novel techniques are becoming available. Some of them are already used clinically, whereas others still need further evaluation. I...

Purpose ¹⁸F-fluorocholine is a positron emission tomography (PET) tracer earlier found to be a marker of macrophage content in carotid plaques. We aimed to assess the feasibility of ¹⁸F-choline PET-MRI to non-invasively localize vulnerable coronary plaques, using optical coherence tomography (OCT) as reference standard. Methods Patients with recent...

Purpose To develop and validate a highly efficient motion compensated free‐breathing isotropic resolution 3D whole‐heart joint T1/T2 mapping sequence with anatomical water/fat imaging at 0.55 T. Methods The proposed sequence takes advantage of shorter T1 at 0.55 T to acquire three interleaved water/fat volumes with inversion‐recovery preparation,...

Introduction Coronary artery disease (CAD) is the leading cause of morbidity and mortality in the developed world. Computed tomography coronary angiography (CTCA), with a spatial resolution of approximately 0.6 mm, is the gold standard in both American and European guidelines for non-invasive anatomical assessment low and intermediate risk patients...

Introduction Heart failure (HF) has reached epidemic proportions, affecting about 64 million people globally and is the main cause of death and disability[1]. Cardiac fibrosis, characterised by changes in type I (COL1) and III (COL3) collagen, drive HF[2,3]. After a myocardial infarction (MI), both COL1 and COL3 increase in the infarcted myocardium...

Contrast enhanced pulmonary vein magnetic resonance angiography (PV CE-MRA) has value in atrial ablation pre-procedural planning. We aimed to provide high fidelity, ECG gated PV CE-MRA accelerated by variable density Cartesian sampling (VD-CASPR) with image navigator (iNAV) respiratory motion correction acquired in under 4 min. We describe its use...

Purpose A 2D image navigator (iNAV) based 3D whole-heart sequence has been used to perform MRI and PET non-rigid respiratory motion correction for hybrid PET/MRI. However, only the PET data acquired during the acquisition of the 3D whole-heart MRI is corrected for respiratory motion. This study introduces and evaluates an MRI-based respiratory moti...

Dark-blood late gadolinium enhancement (LGE) has been shown to improve the visualization and quantification of areas of ischemic scar compared to standard bright-blood LGE. Recently, the performance of various semi-automated quantification methods has been evaluated for the assessment of infarct size using both dark-blood LGE and conventional brigh...

Background Cardiovascular magnetic resonance (CMR) is an important imaging modality for the assessment and management of adult patients with congenital heart disease (CHD). However, conventional techniques for three-dimensional (3D) whole-heart acquisition involve long and unpredictable scan times and methods that accelerate scans via k-space under...

Aims Unstable atherosclerotic plaques have increased activity of myeloperoxidase (MPO). We examined whether molecular magnetic resonance imaging (MRI) of intraplaque MPO activity predicts future atherothrombosis in rabbits and correlates with ruptured human atheroma. Methods and results Plaque MPO activity was assessed in vivo in rabbits (n=12) us...

Purpose Simultaneous PET‐MRI improves inflammatory cardiac disease diagnosis. However, challenges persist in respiratory motion and mis‐registration between free‐breathing 3D PET and 2D breath‐held MR images. We propose a free‐breathing non‐rigid motion‐compensated 3D T2‐mapping sequence enabling whole‐heart myocardial tissue characterization in a...

Background Quantification of three-dimensional (3D) cardiac anatomy is important for the evaluation of cardiovascular diseases. Changes in anatomy are indicative of remodeling processes as the heart tissue adapts to disease. Although robust segmentation methods exist for computed tomography angiography (CTA), few methods exist for whole-heart cardi...

Background Incomplete atrial lesions resulting in pulmonary vein‐left atrium reconnection after pulmonary vein antrum isolation (PVAI), are related to atrial fibrillation (AF) recurrence. Unfortunately, during the PVAI procedure, fluoroscopy and electroanatomic mapping cannot accurately determine the location and size of the ablation lesions in the...

Introduction: Cardiac magnetic resonance (CMR) coronary evaluation remains challenging in teenagers and young adults using conventional respiratory navigation strategies due to irregular respiratory patterns. Motion correction strategies have shown promise in improving efficiency and quality. We sought to evaluate a non-contrast 3D whole-heart sequ...

Purpose To evaluate the feasibility of liver MR fingerprinting (MRF) for quantitative characterization and diagnosis of focal liver lesions. Materials and Methods This single-site, prospective study included 89 participants (mean age, 62 years ± 15 [SD]; 45 women, 44 men) with various focal liver lesions who underwent MRI between October 2021 and A...

Background Unstable atherosclerotic plaque is characterized by increased myeloperoxidase (MPO) activity. As unstable plaque is vulnerable to disruption and ensuing thrombosis, we examined whether plaque MPO activity predicts atherothrombosis in a pre-clinical model and correlates with ruptured human atheroma. Methods To assess if plaque MPO activi...

Objectives Visualizing left atrial anatomy including the pulmonary veins (PVs) is important for planning the procedure of pulmonary vein isolation with ablation in patients with atrial fibrillation (AF). The aims of our study are to investigate the feasibility of the 3D whole-heart bright-blood and black-blood phase-sensitive (BOOST) inversion reco...

Background: Coronary magnetic resonance angiography (coronary MRA) is increasingly being considered as a clinically viable method to investigate coronary artery disease (CAD). Accurate determination of the trigger delay to place the acquisition window within the quiescent part of the cardiac cycle is critical for coronary MRA in order to reduce ca...

Cardiac cine MRI is the gold standard for cardiac functional assessment, but the inherently slow acquisition process creates the necessity of reconstruction approaches for accelerated undersampled acquisitions. Several regularization approaches that exploit spatial-temporal redundancy have been proposed to reconstruct undersampled cardiac cine MRI....

Introduction: Left atrial appendage (LAA) thrombus is the most common source of embolization in atrial fibrillation (AF). Transesophageal echocardiography (TEE) is the gold standard method for LAA thrombus exclusion. Our pilot study aimed to compare the efficacy of a new non-contrast-enhanced cardiac magnetic resonance (CMR) sequence (BOOST) with T...

The detection and characterization of coronary artery stenosis and atherosclerosis using imaging tools are key for clinical decision-making in patients with known or suspected coronary artery disease. In this regard, imaging-based quantification can be improved by choosing the most appropriate imaging modality for diagnosis, treatment and procedura...

Introduction Cardiac fibrosis after myocardial infarction (MI) is a hallmark of the failing heart. Activation of myofibroblasts after MI can lead to excessive deposition of extracellular matrix (ECM) proteins and development of a fibrotic scar rich in collagen and elastin, that can impair cardiac function. Currently, there is a clinical need for di...

Introduction Cardiac fibrosis after myocardial infarction (MI) is a hallmark of the failing heart. Activation of myofibroblasts after MI can lead to excessive deposition of extracellular matrix (ECM) proteins and the development of a fibrotic scar rich in collagen and elastin, that can impair cardiac function. Currently, there is a clinical need fo...

Heart failure (HF) has reached epidemic proportions, affecting approximately 64 million people globally and is the main cause of death and disability.¹ Myocardial fibrosis, characterised by changes in the amount and/or distribution of collagen I and III, impairs cardiac function and relates to adverse outcomes of HF.2 3 Clinically, we rely on indir...

Purpose: Develop a novel approach for 2D breath-hold cardiac cine from a single heartbeat, by combining cardiac motion corrected reconstructions and non-rigidly aligned patch-based regularization. Methods: Conventional cardiac cine imaging is obtained via motion resolved reconstructions of data acquired over multiple heartbeats. Here, we achieve...

Non-Alcoholic Fatty Liver Disease (NAFLD) is the leading cause of chronic liver disease worldwide. Liver biopsy remains the gold-standard for diagnosis and staging of disease. There is a clinical need for non-invasive diagnostic tools for risk stratification, follow-up and monitoring treatment response which are currently lacking, as well as precli...

Purpose To develop an open‐source, high‐performance, easy‐to‐use, extensible, cross‐platform, and general MRI simulation framework (Koma). Methods Koma was developed using the Julia programming language. Like other MRI simulators, it solves the Bloch equations with CPU and GPU parallelization. The inputs are the scanner parameters, the phantom, an...

Purpose Develop a novel approach for accelerated 2D free‐breathing myocardial perfusion via low‐rank motion‐corrected (LRMC) reconstructions. Methods Myocardial perfusion imaging requires high spatial and temporal resolution, despite scan time constraints. Here, we incorporate LRMC models into the reconstruction‐encoding operator, together with hi...

Background: Bright-blood lumen and black-blood vessel wall imaging are required for the comprehensive assessment of aortic disease. These images are usually acquired separately, resulting in long examinations and potential misregistration between images. Purpose: To characterize the performance of an accelerated and respiratory motion-compensate...

Purpose: To assess the clinical performance of the three-dimensional, free-breathing, Magnetization Transfer Contrast Bright-and-black blOOd phase-SensiTive (MTC-BOOST) sequence in adult congenital heart disease (ACHD). Materials and methods: In this prospective study, participants with ACHD undergoing cardiac MRI between July 2020 and March 202...

Quantification of heart geometry is important in the clinical diagnosis of cardiovascular diseases. Changes in geometry are indicative of remodelling processes as the heart tissue adapts to disease. Coronary Computed Tomography Angiography (CCTA) is considered a first line tool for patients at low or intermediate risk of coronary artery disease, wh...

Cardiometabolic disease refers to the spectrum of chronic conditions that include diabetes, hypertension, atheromatosis, non-alcoholic fatty liver disease, and their long-term impact on cardiovascular health. Histological studies have confirmed several modifications at the tissue level in cardiometabolic disease. Recently, quantitative MR methods h...

Myocardial inflammation occurs following activation of the cardiac immune system, producing characteristic changes in the myocardial tissue. Cardiovascular magnetic resonance is the non-invasive imaging gold standard for myocardial tissue characterization, and is able to detect image signal changes that may occur resulting from inflammation, includ...

Cardiovascular magnetic resonance (CMR) features a variety of protocols that are sensitive to respiratory, cardiac, and other types of motion. For some applications, physiological motion corresponds to diagnostic data that can be obtained with dedicated sequences. In many other cases, motion is a major source of image artifacts that must be address...

The diagnosis of cardiac sarcoidosis (CS) remains challenging. While only a small fraction of patients with systemic sarcoidosis present with clinically symptomatic CS, cardiac involvement has been associated with adverse outcomes, such as ventricular arrhythmia, heart block, heart failure and sudden cardiac death. Despite the clinical relevance of...

Background Coronary artery disease (CAD) is the single most common cause of death worldwide. Recent technological developments with coronary cardiovascular magnetic resonance angiography (CCMRA) allow high-resolution free-breathing imaging of the coronary arteries at submillimeter resolution without contrast in a predictable scan time of ~ 10 min....

Cardiovascular magnetic resonance (CMR) is widely used for diagnostic imaging in the pediatric population. In addition to structural congenital heart disease (CHD), for which published guidelines are available, CMR is also performed for non-structural pediatric heart disease, for which guidelines are not available. This article provides guidelines...

Magnetic resonance imaging (MRI) is a versatile modality that can generate high‐resolution images with a variety of tissue contrasts. However, MRI is a slow technique and requires long acquisition times, which increase with higher temporal and spatial resolution and/or when multiple contrasts and large volumetric coverage is required. In order to s...

Purpose To introduce non‐rigid cardiac motion correction into a novel free‐running framework for the simultaneous acquisition of 3D whole‐heart myocardial T1$$ {T}_1 $$ and T2$$ {T}_2 $$ maps and cine images, enabling a ∼$$ \sim $$3‐min scan. Methods Data were acquired using a free‐running 3D golden‐angle radial readout interleaved with inversion...

Magnetic resonance fingerprinting (MRF) is a fast MRI-based technique that allows for multiparametric quantitative characterization of the tissues of interest in a single acquisition. In particular, it has gained attention in the field of cardiac imaging due to its ability to provide simultaneous and co-registered myocardial T1 and T2 mapping in a...

Purpose To develop a fast free‐breathing whole‐heart high‐resolution myocardial T1ρ mapping technique with robust spin‐lock preparation that can be performed at 3 Tesla. Methods An adiabatically excited continuous‐wave spin‐lock module, insensitive to field inhomogeneities, was implemented with an electrocardiogram‐triggered low‐flip angle spoiled...

Background Liver MR fingerprinting (MRF) enables simultaneous quantification of T1, T2, T2*, and proton density fat fraction (PDFF) maps in single breath-hold acquisitions. Histopathologic correlation studies are desired for its clinical use. Purpose To compare liver MRF-derived metrics with separate reference quantitative MRI in participants with...

The aim of this study was to investigate the diagnostic accuracy and reader confidence for late-gadolinium enhancement (LGE) detection of a novel free-breathing, image-based navigated 3D whole-heart LGE sequence with fat–water separation, compared to a free-breathing motion-corrected 2D LGE sequence in patients with ischemic and non-ischemic cardio...

Background: Cardiac MRI plays an important role in the diagnosis and follow-up of patients with congenital heart disease (CHD). Gadolinium-based contrast agents are often needed to overcome flow-related and off-resonance artifacts that can impair the quality of conventional noncontrast 3D imaging. As serial imaging is often required in CHD, the de...

Purpose Free-breathing Magnetization Transfer Contrast Bright blOOd phase SensiTive (MTC-BOOST) is a prototype balanced-Steady-State Free Precession sequence for 3D whole-heart imaging, that employs the endogenous magnetisation transfer contrast mechanism. This achieves reduction of flow and off-resonance artefacts, that often arise with the clinic...

The incidence of abdominal aortic aneurysms (AAAs) has substantially increased during the last 20 years and their rupture remains the third most common cause of sudden death in the cardiovascular field after myocardial infarction and stroke. The only established clinical parameter to assess AAAs is based on the aneurysm size. Novel biomarkers are n...

Background Late gadolinium enhancement (LGE) is a widely used cardiac magnetic resonance imaging (MRI) technique to diagnose a broad range of ischemic and non-ischemic cardiomyopathies. Since its development and validation against histology already more than two decades ago, the clinical utility of LGE and its span of applications have increased co...

Objectives To investigate the efficacy of an in-line non-rigid motion-compensated reconstruction (NRC) in an image-navigated high-resolution three-dimensional late gadolinium enhancement (LGE) sequence with Dixon water–fat separation, in a clinical setting. Methods Forty-seven consecutive patients were enrolled prospectively and examined with 1.5...

Purpose Develop a novel 2D cardiac MR fingerprinting (MRF) approach to enable simultaneous T1, T2, T2*, and fat fraction (FF) myocardial tissue characterization in a single breath‐hold scan. Methods Simultaneous, co‐registered, multi‐parametric mapping of T1, T2, and FF has been recently achieved with cardiac MRF. Here, we further incorporate T2*...

Aims: 18F-sodium fluoride ([18F]fluoride) and gadobutrol are promising probes for positron emission tomography (PET) and magnetic resonance imaging (MRI) characterizing coronary artery disease (CAD) activity. Unlike [18F]fluoride-PET/computed tomography (CT), the potential of PET/MR using [18F]fluoride and gadobutrol simultaneously, has so far not...

Artificial intelligence (AI) refers to the area of knowledge that develops computerised models to perform tasks that typically require human intelligence. These algorithms are programmed to learn and identify patterns from “training data,” that can be subsequently applied to new datasets, without being explicitly programmed to do so. AI is revoluti...

Background: The application of cardiovascular magnetic resonance angiography (CMRA) for the assessment of thoracic aortic disease is often associated with prolonged and unpredictable acquisition times and residual motion artefacts. To overcome these limitations, we have integrated undersampled acquisition with image-based navigators and inline non...