SA Journal of Radiology - Volume 16, Issue 4, 2012
Volume 16, Issue 4, 2012
A semi-automated method for measuring thickness and white matter integrity of the corpus callosum : original articleSource: SA Journal of Radiology 16, pp 130 –133 (2012)More Less
Aim. Diseases affecting cerebral white matter may lead to left-right asymmetries and atrophy of interhemispheric connections, i.e. the corpus callosum (CC). Our aim was to describe and test a semi-automated system that divides the midline CC into a number of segments and determines thickness at each, then performs fibre tracking from these segments.
Methods. Six normal female volunteers (average age 25.8 ± 6.7 years) and a female patient with diagnosed multiple sclerosis (age 26 years) were scanned on a 3T MRI. We performed diffusion-weighted imaging in 12 directions, and calculated diffusion tensors and fractional anisotropy (FA) maps from this pre-processed data. Fibre tracking from a region-of-interest encompassing the entire CC was done. This fibre data, together with FA maps and the unweighted diffusion tensor imaging (DTI) image (b = 0 s/mm2), were imported into a custom tool written in MATLAB. The midline sagittal position was carefully defined by selecting multiple midline points in coronal and axial views and rotating the image volume and fibre co-ordinates accordingly.
Using the customised tool, dorsal and ventral CC contours were manually drawn on the mid-sagittal FA image, initiating automated calculation of a contour midway between these manually drawn lines. The programme was designed to then divide the midline contour into a pre-selected number of segments; from each segment border, perpendicular spokes were projected until they intersected with the dorsal and ventral contours. This technique divided the CC into a pre-set amount of segments, the number of which was limited by the spatial resolution. It was decided to set the number at 40 to ensure that each segment depicted a contiguous strip of voxels across the CC from the dorsal to the ventral contour. The system allows these segments to then be used as seeds for separate fibre tracking in each cerebral hemisphere, and various parameters are automatically plotted as a function of distance along the midline contour. The following parameters are measurable: midline CC thickness; midline FA; fibre volume for each hemisphere (represented as a left/right ratio centred on zero) and mean fibre FA for each hemisphere (also represented as a left/right ratio centred on zero).
Results. The tool proved successful in measuring and plotting CC midline thickness and FA, but was not sensitive for peripheral white matter lesions.
Conclusions. The technique successfully determined values of CC midline thickness, FA and interhemispheric differences. Future research will determine normal values for age and compare CC thickness with peripheral white matter volume loss in large groups of patients, using the semi-automated technique.
Author P. ParagSource: SA Journal of Radiology 16, pp 134 –135 (2012)More Less
Sialoblastomas are rare, locally aggressive, perinatal or congenital salivary gland tumours that mostly originate in the parotid gland. Significant variability in histological range and clinical course exists. This report is of a case of congenital sialoblastoma of the accessory parotid gland.
Multi-detector computer tomography venography (MDCTV) as a diagnostic tool in the management of patients with atypical, complicated and/or recurrent varicose veins : case seriesSource: SA Journal of Radiology 16, pp 136 –138 (2012)More Less
Aim. To evaluate the role of multi-detector computer tomography venography (MDCTV), compared with conventional venography, as a diagnostic tool in the management of patients with atypical, complicated and/or recurrent varicose veins.
Materials and methods. Retrospective review of 21 patients who had undergone both MDCTV and conventional transfemoral or transpopliteal venography between January 2008 and April 2011 for the management of recurrent varicose veins and/or chronic venous ulcers. MDCTV was performed using a 16-slice CT scanner. Spiral acquisition was commenced 180 seconds after intravenous injection of 150 ml of 350 mmol/l iodinated contrast medium. A reconstruction interval of 1.5 mm was used. Conventional venography was performed by the resident vascular surgeon and was followed by stenting or coiling where appropriate.
Results. MDCTV and venography were compared in 21 patients (6 male, 15 female; average age 55 years, range 33 - 78 years); 8 also underwent endovascular iliac vein stenting. The area under the receiver operator curve (ROC) for percentage iliac vein stenosis determined on MDCTV versus venography was 0.75. Four (19%) false-positive iliac vein stenoses were reported on MDCTV. Ten patients underwent gonadal vein coil embolisation. Gonadal vein size >5.2 mm (range 1 - 11 mm) on MDCTV predicted significant venographic reflux requiring coil embolisation. Three (30%) patients who underwent embolisation did not have gonadal vein enlargement on MDCTV.
Conclusion. MDCTV plays an important adjunctive role in the diagnostic workup of patients with complex venous disease. The findings at MDCTV correlate well with conventional venography.
Source: SA Journal of Radiology 16, pp 141 –142 (2012)More Less
Osteogenesis imperfecta (OI) is a heterogeneous group of genetic bone disorders that are characterised by decreased bone mass, increased bone fragility and susceptibility to fractures. The severe, perinatal lethal form (Type II) (OMIM 166210) is characterised by bone fragility, with perinatal fractures, severe bowing of long bones, undermineralisation, and death in the perinatal period owing to respiratory insufficiency. The overall prevalence of OI Type II is unknown. There are three subtypes of OI Type II (A, B and C) that are characterised by different radiological features, and may be caused by different genetic faults. Two fetuses with OI Type IIA are presented.
Source: SA Journal of Radiology 16, pp 144 –146 (2012)More Less
We present a pictorial review of anomalous origin of the left vertebral artery observed in 5 patients imaged in our after-hours trauma radiology unit within a period of 7 days. We raise the question of whether the incidence of anomalous origin of the left vertebral artery quoted in the radiology literature as 5% is really that low, and suggest that the current increased frequency of cross-sectional imaging could elevate the observed incidence of this anomaly in practice. We discuss the implications of vertebral artery anomalies in the endovascular treatment of aortic arch injuries.
Source: SA Journal of Radiology 16, pp 147 –148 (2012)More Less
Rigler's sign was first described in 1941 by L G Rigler as a new radiological sign for recognising free air in the peritoneal cavity on supine radiograph. The presence of pneumoperitoneum allows free intraperitoneal air to be contrasted with intraluminal gas, accentuating the wall of gas-containing viscera. It is observed in infants and very ill patients where only limited radiographs of the abdomen are possible. The football sign was first described by R E Miller in the 1960s. Seen on supine abdominal radiographs, this describes an oval radiolucency resembling an American football. It is important for the radiologist to recognise the supporting signs of pneumoperitoneum, such as Rigler's sign and the football sign, on supine abdominal radiographs, especially in neonates and infants, where erect chest/abdominal radiographs are not always possible.
Source: SA Journal of Radiology 16, pp 149 –150 (2012)More Less
A 5-year-old boy presented to A&E with quadriparesis after a motor vehicle accident. Initial plain radiographs were normal. The CT images of the cranio-cervical junction (CCJ) obtained on admission showed a large acute prepontine retroclival extradural haematoma (REH). There is posterior displacement of the tectorial membrane and compression of the lower pons and medulla. No fractures of the clivus or the upper cervical vertebrae is noted. The cranio-cervical junction bony elements retain their normal alignment with preservation of the powers ratio.
Source: SA Journal of Radiology 16 (2012)More Less
A 40-year-old man presented with acute onset of severe vomiting. From the images provided, describe the relevant findings and provide the most appropriate clinical diagnosis. Please submit your response to Dr Misser at firstname.lastname@example.org not later than 11 January 2013.
Source: SA Journal of Radiology 16, pp 153 –155 (2012)More Less
RSSA - MIP ultrasound mini conference highly successful
First International Day of Radiology - 8 November 2012
Honorary RSSA membership awarded to Professor Dr Robert Hermans
RSSA/Leuven Head and Neck Cancer Imaging Course, Spier Estate, 21 - 23 September 2012
MIP hold seminar at Grey's