Pulsed magneto-motive ultrasound imaging using ultrasmall magnetic nanoprobes

Nano-sized particles are widely regarded as a tool to study biologic events at the cellular and molecular levels. However, only some imaging modalities can visualize interaction between nanoparticles and living cells. We present a new technique, pulsed magneto-motive ultrasound imaging, which is capable of in vivo imaging of magnetic nanoparticles in real time and at sufficient depth. In pulsed magneto-motive ultrasound imaging, an external high-strength pulsed magnetic field is applied to induce the motion within the magnetically labeled tissue and ultrasound is used to detect the induced internal tissue motion. Our experiments demonstrated a sufficient contrast between normal and iron-laden cells labeled with ultrasmall magnetic nanoparticles. Therefore, pulsed magneto-motive ultrasound imaging could become an imaging tool capable of detecting magnetic nanoparticles and characterizing the cellular and molecular composition of deep-lying structures.     

Photoacoustic imaging in cancer detection, diagnosis, and treatment guidance

Imaging modalities play an important role in the clinical management of cancer, including screening, diagnosis, treatment planning and therapy monitoring. Owing to increased research efforts during the past two decades, photoacoustic imaging (a non-ionizing, noninvasive technique capable of visualizing optical absorption properties of tissue at reasonable depth, with the spatial resolution of ultrasound) has emerged. Ultrasound-guided photoacoustics is noted for its ability to provide in vivo morphological and functional information about the tumor within the surrounding tissue. With the recent advent of targeted contrast agents, photoacoustics is now also capable of in vivo molecular imaging, thus facilitating further molecular and cellular characterization of cancer. This review examines the role of photoacoustics and photoacoustic-augmented imaging techniques in comprehensive cancer detection, diagnosis and treatment guidance.     

Comparison of pulsed photothermal radiometry,optical coherence tomography and ultrasound for melanoma thickness measurement in PDMS tissue phantoms

Melanoma accounts for 75% of all skin cancer deaths. Pulsed photothermal radiometry (PPTR), optical coherence tomography (OCT) and ultrasound (US) are non‐invasive imaging techniques that may be used to measure melanoma thickness, thus, determining surgical margins. We constructed a series of PDMS tissue phantoms simulating melanomas of different thicknesses. PPTR, OCT and US measurements were recorded from PDMS tissue phantoms and results were compared in terms of axial imaging range, axial resolution and imaging time. A Monte Carlo simulation and three‐dimensional heat transfer model was constructed to simulate PPTR measurement. Experimental results show that PPTR and US can provide a wide axial imaging range (75 μm–1.7 mm and 120–910 μm respectively) but poor axial resolution (75 and 120 μm respectively) in PDMS tissue phantoms, while OCT has the most superficial axial imaging range (14–450 μm) but highest axial resolution (14 μm). The Monte Carlo simulation and three‐dimensional heat transfer model give good agreement with PPTR measurement. PPTR and US are suited to measure thicker melanoma lesions (<$>><$>400 μm), while OCT is better to measure thin melanoma lesions (<$><<$>400 μm). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Epidemiology of sudden cardiac death in rural South India - insights from the andhra pradesh rural health initiative

Background

Sudden cardiac death (SCD) is a common initial presentation of coronary artery disease (CAD). Despite the growing epidemic of CAD in India, the epidemiology of SCD is largely unknown.

Objective

The objective of the study was to define the prevalence and determinants of sudden cardiac deaths in rural South India.

Methods

Prospective mortality surveillance was conducted in 45 villages (180,162 subjects) in rural South India between January 2006 and October 2007. Trained multipurpose health workers sought to do verbal autopsies within 4 weeks of any death. Detailed questionnaires including comorbidities and circumstances surrounding death were recorded. SCD was adjudicated using the modified Hinkle-Thaler classification.

Results

A total of 1916 deaths occurred in the study population over the 22 month time period and verbal autopsy was obtained in 1827 (95%) subjects. Overall mean age of the deceased was 62 ± 20 years and 1007 (55%) were men. Cardiovascular and cerebrovascular diseases together accounted for 559 deaths (31%), followed by infectious disease (163 deaths, 9%), cancer (126 deaths, 7%) and suicide (93 deaths, 5%).Of the 1827 deaths, after excluding accidental deaths (89 deaths), 309 deaths (17%) met criteria for SCD. Cardiovascular disease was the underlying causes in the majority of the SCD events (231/309 (75%)). On multivariate analyses, previous MI/CAD (p < 0.001, OR 14.25), hypertension (p < 0.001, OR 1.84), and age groups between 40-60 yrs (p=0.029) were significantly associated with SCD.

Conclusion

Sudden cardiac death accounted for up to half of the cardiovascular deaths in rural Southern India. Traditional cardiovascular risk factors were strongly associated with SCD.     

Achieving secondary prevention low-density lipoprotein particle concentration goals using lipoprotein cholesterol-based data

Background

Epidemiologic studies suggest that LDL particle concentration (LDL-P) may remain elevated at guideline recommended LDL cholesterol goals, representing a source of residual risk. We examined the following seven separate lipid parameters in achieving the LDL-P goal of <1000 nmol/L goal for very high risk secondary prevention: total cholesterol to HDL cholesterol ratio, TC/HDL, <3; a composite of ATP-III very high risk targets, LDL-C<70 mg/dL, non-HDL-C<100 mg/dL and TG<150 mg/dL; a composite of standard secondary risk targets, LDL-C<100, non-HDL-C<130, TG<150; LDL phenotype; HDL-C≥40; TG<150; and TG/HDL-C<3.

Methods

We measured ApoB, ApoAI, ultracentrifugation lipoprotein cholesterol and NMR lipoprotein particle concentration in 148 unselected primary and secondary prevention patients.

Results

TC/HDL-C<3 effectively discriminated subjects by LDL-P goal (F = 84.1, p<10⁻⁶). The ATP-III very high risk composite target (LDL-C<70, nonHDL-C<100, TG<150) was also effective (F = 42.8, p<10⁻⁵). However, the standard secondary prevention composite (LDL-C<100, non-HDL-C<130, TG<150) was also effective but yielded higher LDL-P than the very high risk composite (F = 42.0, p<10⁻⁵) with upper 95% confidence interval of LDL-P less than 1000 nmol/L. TG<150 and TG/HDL-C<3 cutpoints both significantly discriminated subjects but the LDL-P upper 95% confidence intervals fell above goal of 1000 nmol/L (F = 15.8, p = 0.0001 and F = 9.7, p = 0.002 respectively). LDL density phenotype neared significance (F = 2.85, p = 0.094) and the HDL-C cutpoint of 40 mg/dL did not discriminate (F = 0.53, p = 0.47) alone or add discriminatory power to ATP-III targets.

Conclusions

A simple composite of ATP-III very high risk lipoprotein cholesterol based treatment targets or TC/HDL-C ratio <3 most effectively identified subjects meeting the secondary prevention target level of LDL-P<1000 nmol/L, providing a potential alternative to advanced lipid testing in many clinical circumstances.