Multimodality Image Fusion and Planning and Dose Delivery for Radiation Therapy

Image-guided radiation therapy (IGRT) relies on the quality of fused images to yield accurate and reproducible patient setup prior to dose delivery. The registration of 2 image datasets can be characterized as hardware-based or software-based image fusion. Hardware-based image fusion is performed by hybrid scanners that combine 2 distinct medical imaging modalities such as positron emission tomography (PET) and computed tomography (CT) into a single device. In hybrid scanners, the patient maintains the same position during both studies making the fusion of image data sets simple. However, it cannot perform temporal image registration where image datasets are acquired at different times. On the other hand, software-based image fusion technique can merge image datasets taken at different times or with different medical imaging modalities. Software-based image fusion can be performed either manually, using landmarks, or automatically. In the automatic image fusion method, the best fit is evaluated using mutual information coefficient. Manual image fusion is typically performed at dose planning and for patient setup prior to dose delivery for IGRT. The fusion of orthogonal live radiographic images taken prior to dose delivery to digitally reconstructed radiographs will be presented. Although manual image fusion has been routinely used, the use of fiducial markers has shortened the fusion time. Automated image fusion should be possible for IGRT because the image datasets are derived basically from the same imaging modality, resulting in further shortening the fusion time. The advantages and limitations of both hardware-based and software-based image fusion methodologies are discussed.     

Micropipette aspiration of human platelets: influence of microtubules and actin filaments on deformability

The deformability of human platelets has been evaluated by micropipette aspiration. Control discoid platelets were about ten times as resistant to deformation in the micropipette as red blood cells. Under a constant negative pressure of 10 cm H2O, control platelets developed extension lengths of 0.74 +/- 0.1 micron. Prior treatment with vincristine, colchicine, or low temperature, all of which remove platelet microtubules, was associated with marked increases in lengths of aspirated segments. Taxol or heavy water, which stabilize microtubules, prevented the increased deformability caused by agents that dissolve microtubules. Cytochalasin B, an agent that inhibits assembly of actin microfilaments, also caused an increase in lengths of aspirated segments that could not be prevented by taxol. Vincristine and cytochalasin B, together, caused a greater increase in deformability than either agent alone. These results indicate important roles for microtubules and microfilaments in platelet deformability.     

Trends of Incidence,Clinical Presentation,and In-Hospital Mortality Among Women With Acute Myocardial Infarction With or Without Spontaneous Coronary Artery Dissection: A Population-Based Analysis

Objectives

The authors sought to determine the clinical characteristics and in-hospital survival of women presenting with acute myocardial infarction (AMI) and spontaneous coronary artery dissection (SCAD).

Influence of metabolic-linked early life factors on the eruption timing of the first primary tooth

Aim

Early eruption of permanent teeth has been associated with childhood obesity and diabetes mellitus, suggesting links between tooth eruption and metabolic conditions. This longitudinal study aimed to identify pre-, peri- and postnatal factors with metabolic consequences during infancy that may affect the eruption timing of the first primary tooth (ETFT) in children from an ethnically heterogeneous population residing within the same community.

Material and methods

Participants were recruited (n = 1033) through the GUSTO (Growing Up in Singapore Towards healthy Outcomes) birth cohort (n = 1237). Oral examinations were performed at 3-month intervals from 6 to 18 months of age. Crude and adjusted analyses, with generalized linear modelling, were conducted to link ETFT to potential determinants occurring during pregnancy, delivery/birth and early infancy.

Results

Overall mean eruption age of the first primary tooth was 8.5 (SD 2.6) months. Earlier tooth eruption was significantly associated with infant’s rate of weight gain during the first 3 months of life and increased maternal childbearing age. Compared to their Chinese counterparts, Malay and Indian children experienced significantly delayed tooth eruption by 1.2 and 1.7 months, respectively.

Conclusions

Infant weight gain from birth to 3 months, ethnicity and maternal childbearing age were significant determinants of first tooth eruption timing. Early life influences can affect primary tooth development, possibly via metabolic pathways.

Clinical relevance

Timing of tooth eruption is linked to general growth and metabolic function. Therefore, it has potential in forecasting oral and systemic conditions such as caries and obesity.