The reliability of routine clinical post-processing software in assessing potential diffusion-weighted MRI "biomarkers" in brain metastases.

BACKGROUND AND PURPOSE: Diffusion MRI characteristics have been used as biomarkers to guide prognosis in cerebral pathologies including brain metastases. The measurement of ADC is often described poorly in clinical and research studies with little detail given to the practical considerations of where to place ROIs, which post processing software package to use and how reproducible the resulting metrics will be. METHOD: We investigated a series of 12 patients with brain metastases and preoperative DWI. Three post processing platforms were used. ROI were placed over the tumour, peritumoural region and across the brain-tumour interface. These recordings were made by a neurosurgeon and a neuroradiologist. Inter-intra-observer variability was assessed using Bland-Altman analysis. An exploratory analysis of DWI with overall survival and tumour type was made. RESULTS: There was excellent correlation between the software packages used for all measures including assessing the whole tumour, selective regions with lowest ADC, the change of ADC across the brain-tumour interface and the relation of the tumour ADC to peritumoural regions and the normal white matter. There was no significant inter- or intra-observer variability for repeated readings. There were significant differences in the mean values obtained using different methodologies and different metrics had differing relationships to overall survival and primary tumour of origin. CONCLUSION: Diffusion weighted MRI metrics offer promise as potential non-invasive biomarkers in brain metastases and a variety of metrics have been shown to be reliably measured using differing platforms and observers.

The effect of sex and handedness on white matter anisotropy: a diffusion tensor magnetic resonance imaging study.

Diffusion tensor magnetic resonance imaging provides a way of assessing the asymmetry of white matter (WM) connectivity, the degree of anisotropic diffusion within a given voxel being a marker of coherently bundled myelinated fibers. Voxel-based statistical analysis was performed on fractional anisotropy (FA) images of 42 right- and 40 left-handers, to assess differences in underlying WM anisotropy and FA asymmetry across the whole brain. Right-handers show greater anisotropy than left-handers in the uncinate fasciculus (UF) within the limbic lobe, and WM underlying prefrontal cortex, medial and inferior frontal gyri. Significantly greater leftward FA asymmetry in cerebellum posterior lobe is seen in left- than right-handers, and males show significantly greater rightward (right-greater-than-left) FA asymmetry in regions of middle occipital lobe, medial temporal gyrus, and a region of the superior longitudinal fasciculus underlying the supramarginal gyrus. Leftward (left-greater-than-right) anisotropy is found in regions of the arcuate fasciculus (AF), UF, and WM underlying pars triangularis in both handedness groups, with right-handers alone showing additional leftward FA asymmetry along the length of the superior temporal gyrus. Overall results indicate that although both handedness groups show anisotropy in similar WM regions, greater anisotropy is observed in right-handers compared with left-handers. The largest differences in FA asymmetry are found between males and females, suggesting a greater effect of sex than handedness on FA asymmetry.

Radiation exposure to children during cardiac catheterization.

The purpose of this study was to assess the suitability of different radiation dosimetry methods and record radiation exposures during paediatric catheterization. Three methods of dosimetry were employed: thermoluminescent dosimetry (TLD), dose-area product and calculation of entrance surface dose from calibrated exposure factors. Examinations included bi-plane fluoroscopy, and cineangiography for diagnosis and treatment of congenital heart disease. The most suitable method of radiation dosimetry for cardiac catheterization is the use of calculated entrance dose or a dose-area product meter. Children were exposed to high levels of radiation during cardiac catheterization but there was a wide variation in radiation dosage. Careful consideration should be given to the suitability of radiation dosimetry for cardiac catheterization.

A comparison of the methods of distraction for stress examination of the acromioclavicular joint.

Acromioclavicular joint disruption is frequently evaluated with a radiographic examination of the joint under stress (weight bearing). Certain authors recommend suspending the weights from the arm, rather than being hand-held, to allow for total muscle relaxation. This study examines the relationship between the coracoclavicular distance measured and the method of distraction. 30 normal subjects participated in the study which used ultrasound (5 MHz linear array) to measure the coracoclavicular distance under four conditions (levels of traction): non-stressed, muscles relaxed; non-stressed, muscles tensed; stressed with 7.5 kg weight hand held; stressed with 7.5 kg weight suspended from the wrist. The data were subjected to a multifactor ANOVA. The level of traction was statistically significant (p < 0.001). The data were then subjected to a Bonferroni multiple comparisons procedure. This showed a difference between the non-stressed and stressed conditions, but there was no difference between the two methods of applying stress to the joint. It was concluded that, in normal subjects, the method of performing the weight bearing examination does not have a significant effect on the magnitude of the coracoclavicular distance.

Technical note: measuring the coracoclavicular distance with ultrasound--a new technique.

The distance between the clavicle and the coracoid process of the scapula is frequently assessed during the radiographic investigation of the acromioclavicular joint. This study defines an ultrasound technique (5 MHz real time linear array) for measuring the coracoclavicular distance, and determines its reliability and validity. A new ultrasonic technique was performed on 49 healthy subjects who had volunteered to participate in the study, having given signed, informed consent. The measuring endpoints for the coracoclavicular distance were the superior border of the clavicle and the superior border of the coracoid process. Three replicate scans were performed on each shoulder. The ultrasound measurements for 19 of the subjects were compared with the measurement obtained from a normal shoulder radiograph (which had previously been requested on clinical grounds). The data were subjected to analysis of variance (ANOVA) and the limits of agreement method of analysis. The mean difference between the radiograph and ultrasound measurements was 0.38 mm. The limits of agreement (95% confidence intervals) were -0.57 (-0.97, -0.17) and 1.33 (0.93, 1.73). Intraoperator and interoperator reliability were evaluated with a multifactor ANOVA and gave p = 0.7 for intraoperator reliability and p = 0.5 for interoperator reliability. The mean of the coefficients of variation for the two operators was 1.84%. The average range for repeated trials (same operator, same subject) was 1.35 mm. The maximum differences in the averages for each operator was 1.2 mm. The ultrasound technique described is a reliable, accurate and valid technique for evaluating the coracoclavicular distance and may usefully supplement the routine radiographic examination of the shoulder in patients presenting for radiographic examination of the acromioclavicular joint.

The role of imaging in the diagnosis of postural disorders related to low back pain.

The function of the spine in humans is support of the body in an upright position, whilst defying gravity, conserving energy and permitting purposeful movement. Low back pain may either be caused by or result in postural disorders. It is an important cause of lost workdays in the industrialised world, with accompanying social and economic implications, and is a common and disabling problem in many sports. Increased awareness of the potential benefits of exercise, together with a change in attitudes in professional sport (placing greater pressure upon individuals to achieve more spectacular results), have resulted in increased pressure on medical services. This article reviews the examination protocols and clinical applications of the diagnostic imaging modalities available for the evaluation and diagnosis of postural disorders related to low back pain. Conventional radiography continues to be of value in demonstrating skeletal relationships and quantifying spinal kinematics. Computed tomography (CT) is widely available and highly accurate in the evaluation of disc herniation and spinal stenosis. Magnetic resonance imaging (MRI) demonstrates discs and the spinal cord with superb morphological accuracy, is painless and noninvasive, and has no known adverse effects or morbidity. It is the most accurate and sensitive modality for diagnosis of subtle occult changes in low back pains in patients where early preventative measures can be adopted to avoid further damage.