Spontaneous intracranial hypo and hypertensions: an imaging review

Cerebrospinal fluid (CSF) pressure changes can manifest as either intracranial hypertension or hypotension. The idiopathic forms are largely under or misdiagnosed. Spontaneous intracranial hypotension occurs due to reduced CSF pressure usually as a result of a spontaneous dural tear. Idiopathic intracranial hypertension (IIH) is a syndrome of elevated intracranial tension without hydrocephalus or mass lesions and with normal CSF composition. Neuroimaging plays an important role in excluding secondary causes of raised intracranial tension. As the clinical presentation is varied, imaging may also help the clinician in arriving at the diagnosis of IIH with the help of a few specific signs. In this review, we attempt to compile the salient magnetic resonance imaging findings in these two conditions. Careful observation of these findings may help in early accurate diagnosis and to provide appropriate early treatment.     

Vascular decomposition using weighted approximate convex decomposition

Objective

Stroke treatment often requires analysis of vascular pathology evaluated using computed tomography (CT) angiography. Due to vascular variability and complexity, finding precise relationships between vessel geometries and arterial pathology is difficult. A new convex shape decomposition strategy was developed to understand complex vascular structures and synthesize a weighted approximate convex decomposition (WACD) method for vascular decomposition in computer-aided diagnosis.

Materials and methods

The vascular tree is decomposed into optimal number of components (determined by an expert). The decomposition is based on two primary features of vascular structures: (i) the branching factor that allows structural decomposition and (ii) the concavity over the vessel surface seen primarily at the site of an aneurysm. Such surfaces are decomposed into subcomponents. Vascular sections are reconstructed using CT angiograms. Next the dual graph is constructed, and edge weights for the graph are computed from shape indices. Graph vertices are iteratively clustered by a mesh decimation operator, while minimizing a cost function related to concavity.

Results

The method was validated by first comparing results with an approximate convex decomposition (ACD) method and next on vessel sections (n = 177) whose number of clusters (ground truth) was predetermined by an expert. In both cases, WACD produced promising results with 84.7 % of the vessel sections correctly clustered and when compared with ACD produced a more effective decomposition. Next, the algorithm was validated in a longitudinal study data of 4 subjects where volumetric and surface area comparisons were made between expert segmented sections and WACD decomposed sections that contained aneurysms. The results showed a mean error rate of 7.8 % for volumetric comparisons and 10.4 % for surface area comparisons.

Conclusion

Decomposition of the cerebral vasculature from CT angiograms into a geometrically optimal set of convex regions may be useful for computer-assisted diagnosis. A new WACD method capable of decomposing complex vessel structures, including bifurcations and aneurysms, was developed and tested with promising results.     

Synthesis of nanosilver using a vitamin C derivative and studies on radiation protection

Silver nanoparticles were prepared from silver nitrate using a vitamin C derivative, 6-palmitoyl ascorbic acid-2-glucoside (PAsAG), via a sonochemical experiment. The resultant golden yellow solution that contained silver nanoparticle-PAsAG complex (SN-PAsAG) of about 5?nm particle sizes was explored for its potential to offer protection to DNA from γ-radiation-induced damages. The presence of SN-PAsAG during irradiation inhibited the disappearance of covalently closed circular (ccc) form of plasmid pBR322 with a dose modifying factor of 1.78. SN-PAsAG protected cellular DNA from radiation-induced damage as evident from comet assay study on mouse spleen cells, irradiated ex vivo. When orally administered with SN-PAsAG at 1 hour prior to whole-body radiation exposure, cellular DNA was found protected from radiation-induced strand breaks in various tissues (spleen cells, bone marrow cells, and blood leucocytes) of animals. Also, SN-PAsAG could enhance the rate of repair of cellular DNA in blood leucocytes and bone marrow cells when administered immediately after radiation exposure. The studies, under in vitro, ex vivo, and in vivo radiation exposure conditions, showed effective radiation protection.     

PHOS GRAPH a novel tool in hyperphosphataemia management in haemodialysis patients

Background: In patients with end stage renal disease, hyperphosphataemia is an almost universal complication. Prolonged hyperphosphataemia is associated with increased morbidity and mortality (Kidney Disease Outcomes Quality Initiative‐K/DOQI, 2004). Pharmacological interventions such as phosphate binders are important in the management of hyperphosphataemia, but these need to be complemented by education regarding binder compliance with phosphate containing foods and limiting excessive phosphate intake. A previous audit carried out in September 2006 of the ‘knowledge of haemodialysis patients on a low phosphate diet and binders’ clearly indicated that we need to improve patients’ knowledge to achieve better control of hyperphosphataemia. The purpose of the study was to assess the effectiveness of an innovative method of patient education (Phos Graph) on the management of serum phosphate in haemodialysis patients with persistent hyperphosphataemia. Methods: The renal dietitians and the renal multi disciplinary team devised a tool called the Phos Graph. The Phos Graph is a novel patient information tool, to inform patients of their phosphate levels relative to their peers on dialysis. The Graph shows the upper limit and lower limit of the normal range, the patient's value for the month as well as their value for the previous month and a rank in comparison to their dialysis peers. Thirty‐four (of 129 patients on haemodialysis) patients with phosphate levels >1.8 mM were identified at the beginning of the study. These patients received a copy of the Phos Graph, an individual dietary assessment and a review of their low phosphate diet by the renal specialist dietitians. This study was carried out for three consecutive months (April to June 2007). The mean serum phosphate levels at the start and finish of the study were compared using the paired student two tailed t‐test. Statistical significance was taken at the P‐value <0.05. Results: Table 1 shows the comparison of phosphate levels for patients who received both, the Phos Graph and dietary intervention and those who received only Phos Graph.

Table 1. Mean phosphate levels during the 3 month study period

Focal neuronal loss, reversible subcortical focal T2 hypointensity in seizures with a nonketotic hyperglycemic hyperosmolar state

Introduction Neuroimaging in seizures associated with nonketotic hyperglycemia (NKH) is considered normal. We report magnetic resonance imaging (MRI) abnormalities in four patients with NKH and seizures. Methods We prospectively evaluated clinical and radiological abnormalities in four patients with NKH during the period March 2004 to December 2005. Results All patients presented with seizures, either simple or complex partial seizures or epilepsia partialis continua. Two of them had transient hemianopia. MRI showed subcortical T2 hypointensity in the occipital white matter and in or around the central sulcus (two patients each), T2 hyperintensity of the overlying cortex (two patients), focal overlying cortical enhancement (three patients) and bilateral striatal hyperintensity (one patient). Diffusion-weighted imaging (DWI) performed in three patients showed restricted diffusion. The ictal semiology and electroencephalographic (EEG) findings correlated with the MRI abnormalities. On clinical recovery, the subcortical T2 hypointensity and striatal hyperintensity reversed in all patients. The initial cortical change evolved to FLAIR hyperintensity suggestive of focal cortical gliosis. The radiological differential diagnosis considered initially included encephalitis, malignancy and hemorrhagic infarct rendering a diagnostic dilemma. Conclusion We identified subcortical T2 hypointensity rather than hyperintensity as a characteristic feature of seizures associated with NKH. Only very few similar reports exist in literature. Reversible bilateral striatal T2 hyperintensity in NKH has not been reported to the best of our knowledge.