Ultrasound and magnetic resonance techniques for the haemodynamic quantification of the peripheral vascular system

The aim of this thesis was to determine whether the blood flow velocities in the peripheral vascular system measured using phase contrast magnetic resonance imaging, PC-MRI, techniques could be used in the same way that blood flow velocities measured using spectral Doppler ultrasound are used to aid in the diagnosis of peripheral vascular disease. Specifically, we aimed to investigate the measurement of maximum velocities and the use of maximum velocity ratios; an area of investigation which has been neglected in studies of PC-MRI blood flow quantification to date. A series of optimisation and comparison studies were carried out using in-house developed test phantoms. Key to the in-vitro work was the establishment of a dual modality flow test system which would allow comparison of identical flow conditions measured using ultrasound and MRI. The work was complemented by in-vivo studies in healthy volunteers. A 4D PC-MRI commercial work-in-progress protocol and software package became available during the study and was evaluated in-vitro and in-vivo using similar methods as for the 2D PC-MRI studies. The main findings of the thesis were that 2D PC-MRI measurement of maximum velocities significantly underestimated those measured using spectral Doppler ultrasound. However, if corrections were applied to account for the overestimation of ultrasound maximum velocity due to spectral broadening, then the two methods were in agreement. In contrast, the use of maximum velocity ratios showed no difference between spectral Doppler ultrasound and 2D PC-MRI measurements. It was noted that one of the potential problems with the use of 2D PC-MRI in the measurement of the maximum velocity at a stenosis is the accurate positioning of the 2D velocity encoded slice in the stenotic jet. 4D PC-MRI, with a time resolved velocity encoded volume dataset, offers a potential solution to this. However, our evaluation of 4D PC-MRI showed that it can significantly underestimate both maximum velocities and maximum velocity ratios in comparison with 2D PC-MRI and spectral Doppler ultrasound and requires further development before it can be used for peripheral vascular applications

Case series of breast fillers and how things may go wrong: radiology point of view

INTRODUCTION: Breast augmentation is a procedure opted by women to overcome sagging breast due to breastfeeding or aging as well as small breast size. Recent years have shown the emergence of a variety of injectable materials on market as breast fillers. These injectable breast fillers have swiftly gained popularity among women, considering the minimal invasiveness of the procedure, nullifying the need for terrifying surgery. Little do they know that the procedure may pose detrimental complications, while visualization of breast parenchyma infiltrated by these fillers is also deemed substandard; posing diagnostic challenges. We present a case series of three patients with prior history of hyaluronic acid and collagen breast injections. REPORT: The first patient is a 37-year-old lady who presented to casualty with worsening shortness of breath, non-productive cough, central chest pain; associated with fever and chills for 2-weeks duration. The second patient is a 34-year-old lady who complained of cough, fever and haemoptysis; associated with shortness of breath for 1-week duration. CT in these cases revealed non thrombotic wedge-shaped peripheral air-space densities. The third patient is a 37‐year‐old female with right breast pain, swelling and redness for 2- weeks duration. Previous collagen breast injection performed 1 year ago had impeded sonographic visualization of the breast parenchyma. MRI breasts showed multiple non- enhancing round and oval shaped lesions exhibiting fat intensity. CONCLUSION: Radiologists should be familiar with the potential risks and hazards as well as limitations of imaging posed by breast fillers such that MRI is required as problem-solving tool

Characterization of alar ligament on 3.0T MRI: a cross-sectional study in IIUM Medical Centre, Kuantan

INTRODUCTION: The main purpose of the study is to compare the normal anatomy of alar ligament on MRI between male and female. The specific objectives are to assess the prevalence of alar ligament visualized on MRI, to describe its characteristics in term of its course, shape and signal homogeneity and to find differences in alar ligament signal intensity between male and female. This study also aims to determine the association between the heights of respondents with alar ligament signal intensity and dimensions. MATERIALS & METHODS: 50 healthy volunteers were studied on 3.0T MR scanner Siemens Magnetom Spectra using 2-mm proton density, T2 and fat-suppression sequences. Alar ligament is depicted in 3 planes and the visualization and variability of the ligament courses, shapes and signal intensity characteristics were determined. The alar ligament dimensions were also measured. RESULTS: Alar ligament was best depicted in coronal plane, followed by sagittal and axial planes. The orientations were laterally ascending in most of the subjects (60%), predominantly oval in shaped (54%) and 67% showed inhomogenous signal. No significant difference of alar ligament signal intensity between male and female respondents. No significant association was found between the heights of the respondents with alar ligament signal intensity and dimensions. CONCLUSION: Employing a 3.0T MR scanner, the alar ligament is best portrayed on coronal plane, followed by sagittal and axial planes. However, tremendous variability of alar ligament as depicted in our data shows that caution needs to be exercised when evaluating alar ligament, especially during circumstances of injury