Chronic kidney failure no barrier to CT angiography.

CT angiography (CTA) using moderate doses of IV contrast in patients with advanced renal failure is a safe procedure that negatively affects renal function in only a small percentage of patients, according to researchers from Baltimore.

But the imaging options are even better with newer MDCT scanners. CTA protocols with low kVp and using half the normal dose of iodinated contrast have even less impact on kidney patients and produce excellent images, said Dr. Barry Daly from the University of Maryland.

In a study presented at last month’s International Society for Computed Tomography (ISCT) meeting in San Francisco, Daly showed how even normal contrast doses had little effect on serum creatinine levels in most patients. Information gained by the studies far outweighs the chance of adverse effects in patients with chronic renal failure, he said.

Daly also showed his latest protocol for low-contrast-dose, low-kV CTA imaging that delivers high image quality with even less risk for these patients.

Don’t skip the CTA

CTA isn’t something you want to skip, even though many centers do just that, he said. Before renal transplant surgery, for example, surgeons need to see what they’re going to be dealing with in the operating room.

“There are big risks going into surgery without CTA in this group because they have the risk of a major change in operative procedure, prolonged surgery, poor graft outcomes, failure to engraft, loss of the organ — which is a total disaster, especially in the setting of matched renal donor transplantation — and, of course, the possibility of missing important pathologies,” Daly said.

Incidental right iliac venous stent
Patient is in renal failure but not yet on dialysis. CTA was acquired at 80 kVp and 360 mAs following administration of 50 mL of 350 mg/mL contrast. Contrast density in the iliac arteries is > 400 HU. Radiation dose is 4.3 mSv. There is an incidental right iliac venous stent. Images courtesy of Dr. Barry Daly.

Daly and colleagues reviewed the use of CTA in 180 potential renal transplant recipients, all with matched donors, “but we were especially interested in looking at a predialysis cohort of 40 patients,” he said.

Patients were assessed for aortoiliac and calcific atherosclerosis, venous thrombosis, and increased incidence of renal cell carcinoma (four to seven times the normal rate in native kidneys). The only prophylaxis was aggressive oral hydration both before and after CTA, he said.

It’s important to find an appropriate place for the engraftment, Daly said. Many patients may require surgical correction with bypass grafts before transplantation can be done.

“Because a lot of these folks have had chronic hemodialysis, it’s not uncommon to find occlusion of the iliac veins,” he said. In a couple of cases, this has become obvious only in the operating room — “with disastrous consequences.”

The study measured serum creatinine (SeCr) and estimated glomerular filtration rate (eGFR) before and after imaging in the 40 predialysis patients. “There was almost no difference between the two groups in mean measurements,” Daly said.

“Nobody had to undergo dialysis, but looking at the changes, there clearly were some shifts that we shouldn’t ignore,” he said.

Post CTA, 27 patients had stable or mean decreased SeCr of 10.2%. Thirteen patients had a mean increase of 6.3%, with one patient showing a 32% rise, and three saw almost no change (0.5-1.5 mg/dL increase).

Change in SeCr after CTA in predialysis cohort of 40 patients

SeCr mean SeCr range eGFR mean
Pre-CTA 5.2 2.9-14.1 20.5
Post-CTA 5.1 2.4-14.2 21.0

A low rate of contrast-induced nephropathy (CIN) in renal patients isn’t all that surprising, Daly said. Newhouse, Katzberg, and others have shown that the risks of IV low-osmolar contrast precipitating CIN have been overestimated.

These previous studies demonstrate that moderate doses of IV contrast are much less nephrotoxic than arterial administration, he said. Many studies without controls failed to allow for other factors affecting renal function, especially in hospital populations. Finally, a 2010 study in Radiologyshowed that low-osmolar contrast may be as safe as iso-osmolar contrast, he noted.

Low-kVp, low-contrast-dose CTA

Daly and colleagues also performed a study of low-kVp, low-contrast-dose CTA in chronic renal failure patients. Why is this necessary if the regular dose is safe?

“The answer, of course, is that lower is always better,” Daly said. Even if the negative effects aren’t as bad as they were feared to be, “there is still a small portion of patients in our group who are still at risk with the conventional dose,” he said, adding that “new CT scanners have enabled new techniques for getting more out of each gram of iodine.”

The technique involves dropping the kV and increasing the mAs. For example, if you drop the tube current from 120 kV to 80 kV, you would increase the mAs by a factor of 2.7. Thus, 120 kVp and 250 mAs become 80 kV and 600 mAs, he said, and for large patients the tube may reach the maximum mAs.

MDCT can be used with extended z-axis coverage to shorten scan times to correspond to a shorter bolus train. Ideally, there should be at least 40 mm to 80 mm of coverage, he advised.

How it works is by now well-known, he said. “The k-edge of iodine is only [33.2] keV, so by dropping our kVp we can actually get considerably increased x-ray absorption. There’s a nearly a twofold increase in iodine attenuation at 80 kV compared to 120 kV.” Thus, the iodine dose can be cut in half while producing similar CT values, according to Daly.

The researchers perform the 80-kV studies on a Brilliance iCT 256 or a Brilliance 64 scanner (Philips Healthcare) using 320 to 350 mgI/mL of contrast.

They inject 35 to 50 mL of contrast at 4 mL per second in a peripheral vein, followed by 40 to 60 mL of a saline chaser at 4 mL per second. Automated bolus tracking is set for a 120- to 150-HU threshold in the aorta just below the hiatus, and the automated minimum scan delay is set to 4.2 to 6.5 seconds, he said.

Tube rotation speed is 0.75 seconds for a 256-slice scanner and 0.75 to 1 second for a 64-detector-row scanner. mAs values are based on patient body mass index (noise present at precontrast phase) with pitch set at maximum for the mAs selected, Daly said.

The resulting images look great, but using iterative reconstruction (iDose5, Philips) allows even lower doses, or the scanning of larger patients using low-kV, low-contrast protocols, he said.

In summary, CTA with a moderate 100-mL dose of iso-osmolar contrast in advanced renal failure “is a safe procedure with a negative impact on renal function in only a small percentage of patients,” Daly said, adding that “these aren’t patients with creatinine of 1.8, these are patients with major renal compromise.”

However, even though the 100-mL contrast protocol has a “very limited negative effect on people … a better option today is low 80-kVp, low-contrast-dose CTA technique with 35 to 50 mL of iso-osmolar contrast,” Daly said.

This very safe technique yields high diagnostic quality and works on most newer CT scanners, he added.

“Finally, if you have the benefit of iterative reconstruction, it improves image quality and allows us to use this technique even in very large patients,” Daly said.

Molecular imaging: Researcher forsees application in myocardial failure.

The landscape of molecular imaging has changed over the past two years, with advances having been made in image-guided drug delivery, gene-based therapy, and cellular therapy. For the latter, cell-labeling methods and image-based magnetic control of cells now enable the monitoring and guidance of therapy. Potential future applications, such as intracellular heating, could place imaging at the very center of therapy delivery.

A panel of experts will show, in a dedicated minicourse today at the European Congress of Radiology (ECR), that molecular imaging can — and soon could — offer improvements in the efficiency of treatment.

2012_02_29_17_52_31_430_p15_Monday_MC23E_Figure8_225 (1)

The recent development of cell-labeling techniques using superparamagnetic nanoparticles has confirmed the role of imaging in monitoring cellular therapies. In particular, researchers have been able to develop high-resolution cellular imaging, using cryoprobes in MR applications. This combination enables high-resolution imaging with a sharp definition of cells in a given organ.

“It’s probably the main discovery we have made over the past two years. By labeling macrophage cells in an ischemic pad of a rat’s foot, we could clearly see the colonized cells and the ischemic territory,” said Professor Olivier Clément, a radiologist working at European Hospital Georges Pompidou in Paris, France.

Projects such as the European Network for Cell Imaging and Tracking (ENCITE), coordinated by the European Institute for Biomedical Imaging and Research and funded by the EU (, have played a major role in this progress, the researcher underlined.

These techniques have shown no adverse effects on cell proliferation and functionalities while conferring magnetic properties on various cell types. The magnetic labeling of living cells creates opportunities for numerous biomedical applications, such as individual cell manipulation and magnetic control of cell migration.

Clément and his team are currently working on facilitating cell-homing in myocardial infarct cellular therapy, by placing an external magnet over the heart to create a local field gradient which induces magnetic targeting.

“We have been working on a study to improve cell-homing in the heart and succeeded in having more cells when using a magnet. We still haven’t been able to show a therapeutic effect with this technique, but other studies have, and they could show a long-term effect, including scar reduction,” he said.

Intracellular heating will, probably soon, become a field of investigation for many researchers. With this method, one will be able to kill cancerous cells and tumors or liberate drugs contained in a liposome by redirecting the heat, created by the use of magnetic fields, to superparamagnetic nanoparticles.

“Let’s imagine that we have a liposome containing drugs and superparamagnetic nanoparticles. With a magnet, you can drag the liposome exactly where you want it; to a tumor, for instance. Then, you just have to heat your liposome, using external microwaves, after which it will break and allow for chemotherapy. This is still a concept, but it could become a third application in the short term,” Clément said.

The transition of these techniques into clinical practice remains a long-term prospect. Many things are still to be done, including toxicity tests. On the bright side, cellular therapies such as blood transfusion and bone marrow transplant already work without image-based monitoring.

Molecular imaging should, however, prove very useful for tissue transplants and regeneration by showing exactly what happens.

“It is not clear at all whether the injected cells will replace organ function, for instance in myocardial failure. A cell can also trigger signals that help the heart to function better. In this case, imaging helps us understand exactly what happens,” said Clément, who foresees its upcoming clinical application in the heart.

“Imaging can significantly improve the accuracy of treatment,” said Dr. Michal Neeman, a researcher working on the development of reporter genes for MRI at Weizmann Institute in Rehovot, Israel.

Reporter genes encode proteins that can be detected by imaging and serve as a surrogate for the activity of a particular promoter area. For example, reporter genes are used to follow the activation of tumor-associated fibroblasts as they penetrate tumors, and follow the expression of angiogenic and lymphangiogenic growth factors by tumors.

Different reporter genes have been developed to allow detection by different imaging modalities. The most common reporter genes are the fluorescent and bioluminescent proteins that emit light and can be detected using sensitive cameras. Reporter genes are now also available for nuclear imaging and MRI.

“I believe the next steps will be to prove efficacy and safety in specific diseases,” Neeman concluded.

The first success story is the treatment of hemophilia B, as shown by a study recently published in the New England Journal of Medicine by researchers at University College London and St. Jude Children’s Research Hospital in the U.S.

Source: ECR 

Outcomes similar with different low-osmolar iodinated contrast agents.

Among patients undergoing coronary angiography or percutaneous coronary interventions with low-osmolar contrast media (LOCM), adverse outcomes are uncommon, with no advantage apparent between different agents.

That finding comes from a retrospective look at data on more than 100,000 patients, reported in theAmerican Journal of Cardiology online March 22 by Dr. James K. Min, with Cedars-Sinai Medical Center in Los Angeles, California, and colleagues.

“In contrast to previous studies that compared LOCM to iso-osmolar contrast media, our study directly compared alternate LOCM for differences in clinical outcomes,” the authors point out.

They note that previous reports have suggested that iohexol may be associated with increased rates of contrast-induced nephropathy (CIN) compared to an iso-osmolar contrast medium, whereas this has not been reported with other LOCM such as ioversol and iopamidol.

To determine if there is any difference between LOCMs, the team looked at outcomes in patients exposed to iohexol (n = 20,136), iopamidol (n = 21,539), or ioversol (n = 66,319) during invasive coronary procedures.

Propensity scoring generated 19,482 matched pairs of patients exposed to iohexol versus ioversol, and 10,204 pairs exposed to iohexol versus iopamidol.

The researchers found no significant difference between the iohexol-ioversol pairs in rates of new inpatient hemodialysis (relative risk 0.72; p = 0.05), inpatient mortality (RR 0.90; p = 0.42), or 30-day readmission for CIN (RR 0.81; p = 0.52).

Outcomes were also similar between the matched iohexol-iopamidol patients in terms of inpatient hemodialysis (RR 1.18; p = 0.45), inpatient mortality (RR 1.09; p = 0.60), or 30-day CIN readmission (RR 1.11; p = 0.82).

“Encouragingly, in this large dataset, even before matching, rates of in-hospital hemodialysis and mortality and 30-day readmission rates for CIN were low for all patients, irrespective of contrast medium used,” Dr. Min and colleagues comment.

“After matching,” they conclude, “we could not identify any significant differences in adverse events for patients who underwent ICA and/or PCI with different LOCM.”


Source: Am J Cardiol 


Hydration before contrast cuts CIN in high-risk patients.

Even patients with advanced kidney disease can steer clear of contrast-induced nephropathy (CIN) if given plenty of hydration, say researchers from the Netherlands. Results from the study of nearly 1,000 patients with stage 3 or 4 kidney disease were published in the June issue of Radiology.

The study found that fewer than 2.5% of the patients examined developed CIN when current guidelines emphasizing hydration were followed, according to the researchers from Radboud University Nijmegen Medical Centre in the Netherlands. The study also found that heart failure, low body mass index, and repeat contrast administration were associated with CIN.

CIN is the third most common cause of acute renal failure in hospitalized patients, and while most cases are limited to mild and transient impairment of renal function, serious morbidity and mortality, as well as longer hospital stays, can occur.

“In current practice, hydration is considered the preventive method of choice; however, evidence supporting its use is limited,” wrote Dr. Corinne Balemans and colleagues. Previous studies have relied on a variety of hydration protocols that were often used inconsistently (Radiology, June 2012, Vol. 263:3 pp. 706-713).

Balemans and colleagues aimed to determine risk factors associated with CIN by evaluating its incidence in patients with an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m2 who received iodinated contrast media intravenously and were treated using current guidelines.

Current CIN guidelines developed in Europe and the U.S. emphasize the identification of patients at high risk for CIN and the use of hydration as a preventive measure, either using normal saline or sodium bicarbonate as an alternative option, they wrote.

In the study, patients with renal insufficiency were evaluated at a special outpatient clinic where CIN was assessed and normal saline hydration was prescribed (Centraal Begeleidings Orgaan guidelines, 2007), with renal function assessed after the procedures.

The researchers stratified all patients with eGFR less than 60 mL/min/1.73 m2 for risk of CIN; those at high risk based on absolute GFR and risk factors were hydrated with 1,000 mL of isotonic saline before and after contrast injection. Serum creatinine was measured three to five days later, and CIN was defined as an increase of 25% or more from baseline. Finally, the authors recorded and compared risk factors between patients with CIN and those without using stepwise multiple logistic regression analysis.

The study included 747 patients (43% female; mean age, 71.3 years ± 10) who underwent 944 procedures. Patients were hydrated in 511 (54.1%) procedures. CIN developed after 23 procedures (2.4%).

Independent predictors of CIN were heart failure (odds ratio, 3.0), body mass index (BMI) (odds ratio, 0.9), and repeated contrast material administration (odds ratio, 2.8), Balemans and colleagues wrote. No patients needed dialysis.

The population was carefully prepared before iodinated contrast injection, and only 7.7% of patients at high risk for CIN did not receive hydration.

“Our study provides reliable estimates of CIN and shows that the incidence of CIN is low in a homogeneous population of patients with stage 3 or 4 chronic kidney disease who underwent treatment in accordance with existing guidelines and who received intravenous iodinated contrast material,” the authors wrote.

In the study, money was saved by restricting hydration to about half of the study population; patients at high risk for CIN were hydrated, whereas those at low risk were not. However, it’s possible the incidence could have been reduced further by a less restrictive policy.

Regarding heart failure, a well-known risk factor for CIN, such patients may have more severe atherosclerotic vascular disease and are more prone to hemodynamic changes during and after procedures. For them, hydration may not be helpful, the authors wrote.

The inverse association between BMI and CIN may not have been reported previously, they noted. Patients with low BMI usually have a lower percentage of muscle mass, and as a result the formulas used to calculate eGFR overestimate renal function, Balemans and colleagues wrote.

Another study reported the association between repeat contrast exposure and CIN. In that study (Trivedi and Foley), the increased risk was even notable in patients with preserved renal function.

As for study limitations, the population was large but the number of events was small. Absolute GFR was used to classify risk, and there is debate about whether GFR should be corrected for body surface area.

The incidence of CIN in patients with stage 3 or 4 chronic kidney disease is low when treated in accordance with current guidelines, the authors concluded.

“Our findings support the efficacy of hydration regimens,” they wrote. “The risk of CIN is increased in patients with heart failure, low BMI, and repeated contrast material administration. These risk factors need to be validated in future studies.”

CT nanoparticle contrast: Good as gold?

CT nanoparticle-based contrast agents are all investigational — and at this point all preclinical — but they’re out there. In a few years, the tiny contrast agent delivery vehicles, which work well in animals, could greatly affect the diagnosis and treatment of disease in humans.

That’s according to David Cormode, PhD, assistant professor of radiology at the University of Pennsylvania. He spoke on nanoparticle CT contrast media at last month’s International Society for Computed Tomography (ISCT) annual meeting in San Francisco.

The integration of nanoparticle CT contrast into the clinical mainstream will take a while, Cormode said, but the process might be speeded up if elements are developed that are cheaper than gold, which is currently used to make the nanoparticles.

Nanoparticles for CT imaging aren’t so different in design and structure from those built for other imaging modalities such as MRI, except that they contain CT contrast agents in their lipid-based cores. Inside every nanoparticle agent is an inner core surrounded by various layered and scattered components including liposomes, micelles, emulsions, and nanocrystals with biocompatible coatings, Cormode said.

CT contrast agents have bigger cores than, for example MR agents, because they need them. Due to CT’s relative insensitivity to contrast compared to other imaging modalities, high-contrast payloads are required for better sensitivity, Cormode said. Nevertheless, they are still quite small, typically less than 4 nm in diameter.

“If you compare the Earth to the size of a soccer ball, it’s about 58 millionth of the size,” he said. “Going from [the soccer ball] to a nanoparticle, it’s about the same factor of difference in sizes.”

In recent years, interest in imaging nanoparticles has soared, with about 80 peer-reviewed studies being published a year, compared with fewer than 10 as recently as 2006, Cormode said. The reason is, quite simply, their vast potential in diagnosing and treating disease.

Nanoparticles are designed to be long-lasting contrast agents that do not need to be readministered in the case of multiple exams being acquired over several hours or potentially even days, Cormode said.

“Compared to agents we are currently using, nanoparticles have long circulation half-lives,” he said. “They can be targeted to allow molecular imaging or specific cells or specific processes. They can be used with spectral CT, and they can also be multifunctional, providing contrast for more than one imaging technique.”

Although no nanoparticle agents are approved for CT, a couple have been cleared for use with MRI, including Doxil, a liposomal formulation of doxorubicin approved for head and neck cancers in the mid-1990s, and Feridex, an iron-oxide nanoparticle contrast agent.

The tiny structures have become more complex in recent years, featuring multiple layers of different coatings, and an antibody or protein used to direct the agent to a biological target. For example, a 2009 in vitro and rat study by Pan and colleagues examined an iodine-loaded agent targeted to fibrin for thrombus imaging, he said.

Representing a new class of nanoparticles designed for CT, the colloidal, radio-opaque and metal-encapsulated polymeric (cROMP) particle offered severalfold enhancement both in vivo and in a rat model, its authors reported, with sensitivity reaching to the low nanomolar particulate .

Key CT nanoparticle studies

In 2006, Mukundan and colleagues tested a blood-pool contrast nanoparticle encapsulating a high concentration of iodine. They injected the agent into five mice and scanned them with micro-CT. The researchers measured high initial enhancement of about 900 HU in the aorta, which plateaued at about 800 HU when measured again two hours later, and there was excellent contrast discrimination between the myocardium and cardiac blood pool .”I imagine if they had continued the study for a longer time, you would have seen the same amount of contrast,” Cormode said.

In a 2010 study of a gold high-density lipoprotein nanoparticle targeted at atherosclerosis, Cormode and colleagues showed that nanoparticles can distinguish several different components in a single scan. The group performed spectral imaging on a preclinical CT scanner developed by Philips Healthcare to differentiate gold (Au-HDL), iodine-based contrast, and calcium phosphate in phantoms. The gold nanoparticles were injected in mice and followed 24 hours later by an iodine-based contrast agent.

The gold particles were detected in the aortas of the mice, while the iodine-based contrast agent was highlighted in the blood and the calcium-rich tissue of the skeleton during a single CT scan. Microscopy showed that the gold was primarily localized in macrophages in the aorta, thereby showing that spectral CT also provided information about the macrophage burden 

“You can use nanoparticles … to extract several different parameters at the same time,” Cormode said of the study.

Also in 2010, Cormode collaborated with van Schooneveld et al to examine an all-in-one contrast agent for MRI, CT, and fluorescence imaging. The researchers created a gold/silica nanoparticle agent to enhance macrophage cells in vitro using MRI, CT, and fluoroscopy and mice livers in vivo using MRI and CT. The agent is useful in many applications, including cell tracking and target-specific molecular imaging, and is “a step in the direction of truly multimodal imaging,” the authors wrote.

Diagnostic and therapeutic

Gold nanoparticle-based contrast was also the agent of choice in a study by von Maltzahn et al, who used a gold nanorod agent to visualize and then ablate tumors in mice. The nanomaterials improved the specificity of cancer ablation by homing into tumors and acting as antennas for externally applied radiofrequency ablation, the authors .

The polyethylene glycol (PEG)-protected gold nanorods “actually absorb laser radiation very strongly, and when they do they heat up the surrounding material,” Cormode said of the study. “This can be used as a kind of hyperthermia technique” to completely eradicate the tumors, he noted.

In summary, CT nanoparticle contrast agents “are out there, but gold is sort of expensive and we need to create cheaper agents,” Cormode said. In addition, “extensive clearance and toxicity testing” will be needed before the agents are ready for routine clinical use.

Cornell dots show promise in targeting cancer cells during surgery.

The U.S. Food and Drug Administration (FDA) has approved the first clinical trial of a new technology that uses radiolabeled nanoparticles to brighten cancer cells so they can be detected by a PET-optical imaging camera.

Researchers from Memorial Sloan-Kettering Cancer Center (MSKCC) and Cornell University are collaborating with Hybrid Silica Technologies, a Cornell start-up company, and Dutch optical imaging developer O2view on the project and clinical trial.

The FDA’s investigational new drug (IND) approval for the study represents the first inorganic particle platform of its class to be used for multiple clinical indications, according to co-researcher Dr. Michelle Bradbury, a neuroradiologist at MSKCC and assistant professor of radiology at Weill Cornell Medical College.

The trial will explore the applications of cancer targeting and future therapeutic diagnostics, as well as cancer disease staging and tumor burden assessment through lymph node mapping.

Multiple applications

“Cancer has largely been the heavy hitter for nanoparticle probes, and I think there are overlaps with other diseases where institutions could make use of such types of particles,” Bradbury “We are developing the [therapeutic diagnostic] probes and using them for surgical applications, mainly lymph node mapping.”

The so-called “Cornell dots” are silica spheres approximately 6 nm in diameter that enclose several dye molecules. The silica shell, which is essentially glass, is chemically inert and small enough to pass through the body and exit in the urine. For clinical applications, the dots are coated with neutral molecules — polyethylene glycol (PEG) — so the body will not recognize them as foreign substances and activate a patient’s immune system to reject them.

To make the nanoparticles adhere to tumor cells, organic molecules that bind to tumor surfaces or specific locations within tumors can be attached to the PEG shell. When exposed to near-infrared light, the dots become brighter and help identify the targeted cancer cells.

Nanoparticle half-life

Nanoparticles in general can linger in the bloodstream for many hours and even days, depending on their size. Given their 6-nm size, the nanoparticles have a half-life of approximately six hours in the bloodstream before evacuation through the kidneys. “Within a 24-hour period,” Bradbury said, “50% may be cleared through the kidneys.”

Among the researchers’ goals in this trial is to validate the pharmacokinetics and dosimetry of the nanoparticles and PET-optical imaging technology for safe use in humans. Researchers also will collect blood and urine samples to see how different parts of the body, besides organs, react to the nanoparticles.

The study will include five metastatic melanoma patients as its first enrollees. “If all goes well with a few patients, we hope to proceed with a targeted study,” Bradbury said.

Surgical information

The technology, the researchers believe, could be particularly beneficial during surgical treatment, allowing surgeons to see the invasive or metastatic spread to lymph nodes and distant organs and illustrating the extent of treatment response.

Initially, the surgical applications will include cancer within the complex area of the head and neck. With the help of the nanoparticles and PET-optical imaging camera, surgeons will be able to detect the activity of the lymph nodes.

Currently, Bradbury explained, physicians have little or nothing to refer to during surgery other than a preclinical scan — and compared to the scan, the patient is now in a totally different position on the table.

“How would they know where they are in the neck?” she asked. “They just don’t [know], so they want tools so they can see what they are doing and see the nodes in relation to vital structures, such as nerves. They don’t want to pick up activity from a lymph node plus an adjacent tumor, which would be easy to do, if you don’t know where you are exactly.”

Nanoparticles in mice

Researchers have already had some success with the nanoparticles and the PET-optical imaging technology in a preclinical study in mice. Among the conclusions is that the nanoparticles have been “optimized for efficient renal clearance” and “concurrently achieved specific tumor targeting” (Journal of Clinical Investigation, July 2011, Vol. 121:7, pp. 2768-2780).

In addition, the multimodal silica nanoparticles exhibit “what we believe to be a unique combination of structural, optical, and biological properties,” wrote lead study authors Dr. Miriam Benezra and Dr. Oula Penate-Medina and colleagues.

To be clinically successful, the group added, the “next generation of nanoparticle agents should be tumor selective, nontoxic, and exhibit favorable targeting and clearance profiles. Developing probes meeting these criteria is challenging, requiring comprehensive in vivo evaluations.”


Virgin Galactic’s Record-Breaking SpaceShipTwo Test Flight Sets Stage for Passenger Trips By 2014.

Virgin Galactic‘s private spaceship flew higher and faster than it ever had before on Thursday (Sept. 5), giving company officials confidence that the vehicle is on track to start carrying passengers on suborbital jaunts next year.


In its second-ever rocket-powered test flight, which took off Thursday morning from the Mojave Air and Space Port in California, Virgin Galactic’s SpaceShipTwo reached a maximum altitude of 65,000 feet (19,800 meters) and a top speed of Mach 1.6, or 1.6 times the speed of sound (which is about 761 mph, or 1,225 km/h, at sea level).


The six-passenger space plane got up to 56,000 feet (17,000 m) and Mach 1.2 during its only previous powered flight, which occurred on April 29. SpaceShipTwo’s engine burned for 16 seconds during that first test, compared to 20 seconds on Thursday, Virgin Galactic officials said.

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