Publications by authors named "Peter Drivas"

Objective: To evaluate dynamic magnetic resonance dacryocystography (MRDCG) in eyes with functional epiphora.

Methods: We included prospective eyes with epiphora if no alternative cause was found on clinical examination, were patent on syringing, had no obstruction or stenosis on DCG, and had an abnormal DSG. MRDCG was performed to qualitatively assess for block or patency and quantitatively measure tear transit time.

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Importance: This study introduces a new technique in the assessment of nasolacrimal drainage with magnetic resonance imaging.

Background: To describe a new dynamic magnetic resonance dacryocystography (MRDCG) protocol and report normative findings on asymptomatic lacrimal drainage systems.

Design: A prospective observational study at the Royal Adelaide Hospital.

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Background: Wave intensity analysis (WIA) of the coronary arteries allows description of the predominant mechanisms influencing coronary flow over the cardiac cycle. The data are traditionally derived from pressure and velocity changes measured invasively in the coronary artery. Cardiovascular magnetic resonance (CMR) allows measurement of coronary velocities using phase velocity mapping and derivation of central aortic pressure from aortic distension.

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Background: T2* magnetic resonance of tissue iron concentration has improved the outcome of transfusion dependant anaemia patients. Clinical evaluation is performed at 1.5 T but scanners operating at 3 T are increasing in numbers.

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Background: There is a need for improved worldwide access to tissue iron quantification using T2* cardiovascular magnetic resonance (CMR). One route to facilitate this would be simple in-line T2* analysis widely available on MR scanners. We therefore compared our clinically validated and established T2* method at Royal Brompton Hospital (RBH T2*) against a novel work-in-progress (WIP) sequence with in-line T2* measurement from Siemens (WIP T2*).

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Cardiovascular magnetic resonance is a non-invasive imaging modality which is emerging as important tool for the investigation and management of pediatric cardiovascular disease. In this review we describe the key technical and practical differences between scanning children and adults, and highlight some important considerations that must be taken into account for this patient population. Using case examples commonly seen in clinical practice, we discuss the important clinical applications of cardiovascular magnetic resonance, and briefly highlight key future developments in this field.

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Background: Myocardial black blood (BB) T2* relaxometry at 1.5T provides robust, reproducible and calibrated non-invasive assessment of cardiac iron burden. In vitro data has shown that like T2*, novel native Modified Look-Locker Inversion recovery (MOLLI) T1 shortens with increasing tissue iron.

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Objective: Premature atherosclerosis has been observed among HIV-infected individuals with high cardiovascular risk using one-dimensional ultrasound carotid intima-media thickness. We evaluated the assessment of HIV-infected individuals with low traditional cardiovascular disease risk using cardiovascular magnetic resonance, which allows three-dimensional assessment of the carotid artery wall.

Methods: Carotid cardiovascular magnetic resonance was performed in 33 HIV-infected individuals (cases) (19 male, 14 female), and 35 HIV-negative controls (20 male, 15 female).

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Background: Temporal patterns of coronary blood flow velocity can provide important information on disease state and are currently assessed invasively using a Doppler guidewire. A non-invasive alternative would be beneficial as it would allow study of a wider patient population and serial scanning.

Methods: A retrospectively-gated breath-hold spiral phase velocity mapping sequence (TR 19 ms) was developed at 3 Tesla.

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Purpose: To develop an accurate method of performing free-breathing coil calibration for application to parallel imaging reconstructions of dynamic single-shot datasets.

Methods: Coil calibration data are produced through acquisition of multiple prescans before the accelerated scan, applied during free-breathing. These multiple free-breathing prescans (MFPs) provide the necessary coil information for accurate parallel imaging reconstruction of each accelerated frame of a dynamic series, under guidance of an appropriate respiratory position based matching algorithm.

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The prevalence of obstructive sleep apnoea (OSA) increases with age, yet the risk factors for OSA in older people remain poorly understood. This study aimed to define the age-related changes in upper airway morphology in carefully matched groups of healthy older (>60 years, n=11) and younger (<40 years, n=14) males, using direct (magnetic resonance imaging (MRI)) and indirect (acoustic reflection) imaging. The median (interquartile range) combined retropalatal and retroglossal pharyngeal length was greater in older than in younger males (older 8.

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Purpose: To develop navigator-gated free-breathing 3D spiral late gadolinium enhancement (LGE) imaging of the left ventricle at 3T and compare it with conventional breath-hold 2D Cartesian imaging.

Materials And Methods: Equivalent slices from 3D spiral and multislice 2D Cartesian acquisitions were compared in 15 subjects in terms of image quality (1, nondiagnostic to 5, excellent), sharpness (1-3), and presence of artifacts (0-2). Blood signal-to-noise ratio (SNR), blood/myocardium contrast-to-noise ratio (CNR), and quantitative sharpness were also compared.

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Purpose: Navigator-gated three-dimensional (3D) late gadolinium enhancement (LGE) imaging demonstrates scarring following ablation of atrial fibrillation. An artifact originating from the slice-selective navigator-restore pulse is frequently present in the right pulmonary veins (PVs), obscuring the walls and making quantification of enhancement difficult. We describe a simple sequence modification to greatly reduce or remove this artifact.

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Purpose: Acquisition durations of navigator-gated high-resolution three-dimensional late gadolinium enhancement studies may typically be up to 10 min, depending on the respiratory efficiency and heart rate. Implementation of the continuously adaptive windowing strategy (CLAWS) could increase respiratory efficiency, but the resulting non-smooth k-space acquisition order during gadolinium wash-out could result in increased artifact.

Methods: Navigator-gated three-dimensional late gadolinium enhancement acquisitions were performed in 18 patients using tracking end-expiratory accept/reject (EE-ARA) and CLAWS algorithms in random order.

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Investigation of pesticide impacts on human health depends on good measures of exposure. Historical exposure data are needed to study health outcomes, such as cancer, that involve long latency periods, and other outcomes that are a function of the timing of exposure. Environmental or biological samples collected at the time of epidemiologic study may not represent historical exposure levels.

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