Differentiating recurrent tumours from post-treatment changes in head and neck cancers: does diffusion-weighted MRI solve the eternal dilemma?

AIM: To evaluate the utility of diffusion-weighted imaging (DWI) in differentiating post-treatment changes from tumour recurrence in head and neck cancers and to establish a threshold apparent diffusion coefficient (ADC) value to differentiate the two conditions. MATERIALS AND METHODS: This was a prospective study of 80 treated head and neck cancer patients. The patient cohort consisted of a wide spectrum of head and neck sites, including the oral cavity, oropharynx, larynx, hypopharynx, paranasal sinuses, orbits, salivary glands, and infra-temporal fossa. Qualitative analysis of the diffusion images and quantitative analysis of the corresponding ADC maps was performed and the data were correlated with histopathological findings and clinical examinations. RESULTS: The mean ADC value of recurrent tumours in the present cohort was 0. 932±0.19×10-3 mm2/s and the mean ADC value of lesions representing post-treatment changes was 1.394±0.32×10-3 mm2/s. A threshold ADC value of 1.2×10-3mm2/s used to differentiate post-treatment changes from recurrent head and neck cancers showed the highest combined sensitivity of 90.13%, specificity of 82.5%, accuracy of 86.4%, positive predictive value of 84.4%, negative predictive value of 88.9%, and mean kappa measurement of agreement of 72.8. CONCLUSION: Combined qualitative and quantitative analysis of DWI is a useful non-invasive technique to differentiate recurrent head and neck malignancies from post-treatment changes using a threshold ADC value.

Uptake of clinical yeast isolates by human epithelial cell line.

OBJECTIVE: The occurrence of yeast infections in humans has increased, with the species belonging to genus Candida still being the most common cause of infection. Nevertheless, infections caused by less common yeasts have been widely reported in recent years. The main objective of this study was to assess the potential of these less common saprophytic yeasts to invade the host cell, which is essential for causing systemic infections. MATERIAL AND METHODS: Various yeast isolates were identified by DNA sequence information of PCR amplified ITS region. The purported saprophytic yeasts were characterized for internalization by mammalian cells in vitro, by staining the F-actin. CONCLUSION: The identification of different yeast isolates from various patients revealed that 70% of the isolates belonged to the genus Candida, while remaining 30% of the isolates were yeasts not belonging to genus Candida. These non-Candida clinical isolates, either in yeast or hyphal forms, were efficiently internalized by human epithelial cells. The internalization was marked by a process of actin polymerization surrounding the invading yeast. Such uptake by epithelial cells signifies traversal of cell barrier by yeast cells during infection in vivo.

Magnetic resonance imaging of human dental pulp stem cells in vitro and in vivo.

Recent advances in stem cell research have shown the promising nature of mesenchymal stem cells as plausible candidates for cell-based regenerative medicine. Many studies reported the use of human dental pulp stem cells (hDPSCs), which possess self-renewal capacity, high proliferation potential, and the ability to undergo multilineage differentiation. Together with this therapeutic approach, development of effective, noninvasive and nontoxic imaging techniques for visualizing and tracking the cells in vivo is crucial for the evaluation and improvement of stem cell therapy. Magnetic resonance imaging (MRI) is one of the most powerful diagnostic imaging techniques currently available for in vivo diagnosis and has been proposed as the most attractive modality for monitoring stem cell migration. The aim of this study was to investigate the labeling efficiency of hDPSCs using superparamagnetic iron oxide (SPIO) particles in order to allow visualization using in vitro and in vivo MRI without influencing cellular metabolism. MRI and transmission electron microscopy (TEM) showed optimal uptake with low SPIO concentrations of 15 µg/ml in combination with 0.75 µg/ml poly-L-lysine (PLL) resulting in more than 13 pg iron/cell and an in vitro detection limit of 50 labeled cells/µl. Very low SPIO concentrations in the culture medium resulted in extremely high labeling efficiency not reported before. For these conditions, tetrazolium salt assays showed no adverse effects on cell viability. Furthermore, in vivo MRI was performed to detect labeled hDPSCs transplanted into the brain of Rag 2-γ C immune-deficient mice. Transplanted cells did not show any signs of tumorgenecity or teratoma formation during the studied time course. We have reported on a labeling and imaging strategy to visualize human dental pulp stem cells in vivo using MRI. These data provide a solid base to allow cell tracking in future regenerative studies in the brain longitudinally.

Ipsilateral stroke with uncrossed pyramidal tracts and underlying right internal carotid artery stenosis treated with percutaneous transluminal angioplasty and stenting. A rare case report and review of the literature.

We present a unique case of ipsilateral stroke in a 55-year-old right-handed hypertensive man with proven uncrossed pyramidal tract demonstrated by tractography. Diffusion-weighted imaging disclosed small acute ischemic infarcts in the right corona radiata with MR angiography showing narrowing of the right internal carotid artery. Significant carotid stenosis of right internal carotid artery (ICA) was detected on digital subtraction angiography as the underlying cause and subsequently treated with percutananeous transluminal angioplasty and stenting with good outcome. The presence of uncrossed pyramidal tract was confirmed by diffusion tensor imaging tractography. To our knowledge there are few reports of ipsilateral stroke with proven uncrossed pyramidal tracts described in the literature. This is the first documented report of ipsilateral stroke with uncrossed fibre tracts due to underlying critical stenosis of the ICA treated successfully with a good recovery.

Pre- and posttreatment MR imaging findings in lead encephalopathy.

A 41-year-old man suspected of having lead poisoning was evaluated with MR imaging before and after British antilewisite therapy. The MR imaging findings showed bilateral symmetric involvement of the occipital lobe, affecting predominantly the gray-white matter junction and the subcortical white matter. A right cerebellar lesion was noted, with focal hyperintensities involving the gray-white matter. Similar lesions were seen in the temporal, parietal, and frontal regions. These lesions resolved after chelation therapy.