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Old 07-16-2011, 10:02 AM
gdpawel gdpawel is offline
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Default Pet Scans in Oncology

Although PET has set its sights beyond the realm of cancer imaging, oncology remains the cornerstone application for the modality.

PET has replaced some studies that are considered conventional nuclear medicine because of its tremendous capability to image the biochemistry of tumors noninvasively, according to Dr. Steven Larson, chief of nuclear medicine at Memorial Sloan-Kettering Medical Center in New York City.

PET has been approved by the FDA for characterization of solitary pulmonary nodules, lung cancer staging, evaluation of colorectal cancer in patients with rising levels of cardioembryonic antigen, and imaging of patients who have lymphoma and melanoma. Researchers at several institutions are focused on establishing PET's comparative accuracy in other cancers.

One of the primary research goals is to improve the noninvasive staging of tumors for better surgical management, and looking at specific circumstances, such as esophageal cancer, to validate PET as a diagnostic tool.

Other sites are focusing on advancing PET's applications in brain tumor, which was the first clinical indication for fluorodeoxyglucose (FDG) in tumor imaging. Researchers have found the technique useful in patients with both metastatic and primary brain tumor who have been treated with chemotherapy and whose MRI scans show an increase in the residual abnormality (like necrotizing leukoencephalopathy).

Morphologically, it's impossible to distinguish radiation change (like radiation necrosis) from recurrent tumor. PET in this situation is very accurate in distinguishing between those two diagnoses. And it is often used to base treatment decisions without further biopsies, since brain biopsy isn't easy and is very invasive.

In staging cancers of the head and neck, comparative studies report a slight statistical advantage for PET over CT or MRI, with some published reports documenting high sensitivity and specificity for PET. For example, FDG PET is more sensitive in detecting primary tumors (PET sensitivity, 89% to 100%; CT or MRI sensitivity, 68% to 92%), and lymph node involvement (PET sensitivity, 74% to 100%; CT or MRI sensitivity, 36% to 94%).

Other studies, however, document few such differences. But in no study has PET proved inferior to either CT or MRI, according to Dr. Val Lowe, a nuclear medicine specialist at the Mayo Clinic.

Detecting the recurrence of disease in head and neck cancer is an area where PET clearly excels. In a prospective study of patients post-therapy, researchers found that PET can detect recurrence when it may be unidentifiable by other clinical methods.

PET is very useful in looking for residual disease after primary treatment, usually chemo and radiation, to determine whether salvage surgery is necessary. It is useful in detecting mediastinal disease, which doesn't happen very often, but occasionally can occur with non-enlarged lymph nodes, so it's missed by CT.

Another PET application seeing widespread use is in differentiating recurrent tumor from scar after therapy for colorectal cancer. The technique has also made inroads in assessing thyroid tumor recurrence in postsurgical patients.

The diagnostic evaluation usually includes another radioiodine scan, but that scan is negative about one-third of the time. So most physicians then order an ultrasound or MRI of the neck, but those studies are negative more than half the time. About two-thirds of these patients can have their recurrent thyroid cancers localized by PET, permitting either follow-up surgery or external beam radiation therapy.
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Old 07-16-2011, 10:07 AM
gdpawel gdpawel is offline
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Default Oncology Applications

Early Detection: Since PET images biochemical activity, it can accurately predict whether a tumor is benign or malignant, thereby avoiding surgical biopsy when the PET scan is negative. Conversely, since a PET scan images the entire body, confirmation of non-local metastasis can alter treatment plans. In some cases this may mean a change from surgical intervention to chemotherapy. Some patients may avoid unwarranted surgery and a delay in the most appropriate treatment in these cases.

Staging of CA: PET is extremely sensitive in determining the full extent of disease, especially in lymphoma, melanoma, breast, lung, colon and ovarian cancers. Confirmation of advanced metastases allows the physician and patient to more accurately decide on how to proceed, especially if the patient is against extraordinary measures or decides not to undergo the rigors of chemotherapy in the time they have remaining. PET improves the quality of a patient's remaining time in these cases.

Checking for Recurrences: PET is the most accurate diagnostic procedure to differentiate tumor recurrences from radiation necrosis or post-surgical changes. Patients can often avoid additional surgery in these cases.

Tracking the Effectiveness of Cancer Treatment

Research indicates that PET is playing a growing role in tracking the effectiveness of chemotherapy and evaluating early response to a selected drug. The level of tumor metabolism is compared on PET scans taken before and after chemotherapy. A successful response seen on a PET scan frequently precedes alterations in anatomy and would therefore be an earlier indicator of tumor shrinkage than would be seen with other diagnostic modalities. The same assessment applies to tracking the effectiveness of radiation therapy.

Applications in Oncology: Tumor-therapy Monitoring

Evaluating therapeutic efficacy

PET is useful in a variety of therapy-monitoring applications, including distinguishing between radiation necrosis and recurrence; determining the resectability of a recurrence; and evaluating response to chemotherapy or radiation therapy.

This is because effective therapy leads to rapid reductions in the glucose uptake levels of tumors. PET tracers can easily reveal this drop in metabolic activity and show - sometimes within minutes or hours - whether a patient is responding positively to a particular course of treatment. With this information, physicians can quickly modify less effective therapy, thereby improving patient outcomes and reducing the cost of ineffective treatment.

But not all cancers show up on FDG Pet scans, because some use glutamine metabolism rather than glycolysis, or they could depend on another nutrient, amino acid glycine. Researchers know very little about how the body regulates glycine metabolism, yet its contribution to tumor cell proliferation only increases the evidence that changes in metabolism are a cause of cancer, not just a consequence of it.

PET has demonstrated efficacy for monitoring therapeutic response in a wide range of cancers, including breast, lung, ovarian, head, neck, and thyroid cancers, as well as melanoma and lymphoma.

Can cancer patients be evaluated annually with Pet scanning?

A PET scan is a diagnostic test (ordered to answer a specific question) as opposed to a screening test (ordered to try rule out a particular condition). PET scans are used in combination with other radiology procedures (MRI, CT, X-rays) to help make a diagnosis or follow a patient that has undergone treatment. They are not used as screening tests for cancer.

A good screening test needs to be safe, specific (positive only for the particular condition being screened), and make a difference in survival because it allows for early initiation of treatment. There are a number of reasons for a PET scan to have increased activity, not just cancer. If a PET scan was used to screen for cancer and increased activity was found, this may lead to undue anxiety and further unnecessary evaluations and procedures that could be harmful to the patient.

Furthermore, PET scans are not helpful in all types of cancer. Thus it is not feasible to do a PET scan on everyone annually for cancer screening. Below are the indications for FDG-PET scans (both Medicare approved and non-Medicare approved). Typically a PET scan costs between US $ 1500 to 2500. Frequently patients who pay from their own pockets to get a scan when their insurance company has denied.
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Last edited by gdpawel : 01-30-2013 at 05:46 PM. Reason: spelling errors
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Old 09-26-2011, 01:39 PM
gdpawel gdpawel is offline
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Default Explanation of Pet

A Regular Bone Scan cannot distinguish what a lesion represents and cannot differentiate between a tumor, an infection or a fracture. A Triple Phase Bone Scan may occasionally be helpful in determining benign from malignant lesions. Enhanced (contrast) agents increase the sensitivity, conspicuity and accuracy of an exam. The agent most commonly used is Gadolinium. The proper medical protocol for all Brain and Spinal MRI's for metastatic diseases is "enhanced" with contrast.

However, with the introduction of the Pet Scan, it is useful in a variety of therapy-monitoring applications, including distinguishing between radiation necrosis and recurrence, determining the resectability of a recurrence and evaluating response to chemotherapy or radiation therapy. Futhermore, Pet has demonstrated efficacy for monitoring therapeutic response in a wide range of cancers, including breast, lung, ovarian, head, neck, and thyroid cancers, as well as melanoma and lymphoma.

A small injection of a radioactive sugar is given to the patient. The sugar travels thru the body and gets "gobbled up" by cancer cells. Cancer cells metabolize the sugar and trap it. Since the sugar is radioactive, it gives off energies that can be captured and turned into a picture. The PET scan shows what is going on at the cellular level (cancer cells eating up the sugar). While this is very informative, the integrated PET/CT gives much more information to the physician so they can tailor the treatment more specifically to each patient.

When the patient lies down to be scanned, a whole body CT scan is done on the patient, which shows exemplary anatomic detail. The patient is then moved a little further into the tube to get the PET scan performed. Since these two tests are integrated into one machine, the technician can overlay the physiologic data (PET) with the anatomic data (CT) which will tell the patients physician exactly where the tumor is, and how they can plan their therapy to kill it. A PET/CT scan takes on average 20 minutes, while the more antiquated PET or software fused PET takes in excess of one hour, and is nowhere near as informative to the physician.

Most insurances (including Medicare) pay for PET/CT scans because they change the patient management up to 40% of the time, and may help avoid unnecessary and costly surgery.

This scan is extremely important in lung, colo-rectal, ovarian, lymphoma, and breast cancers especially where there is mediastinal involvement or a question if there is chest wall involvement, or lymph node involvement. With the "fused" PET/CT, if there is a spot in the mediastinum, you will know exactly if it is a particular lymph node, or a mass, which is extremely important for Radiation Therapy planning or surgery. A plain PET scan or a PET scan that uses software fusion is not as accurate as an integrated PET/CT. It could make a world of difference.

According to radiology and imaging services at hospitals, patients with diabetes need to follow special instructions for a PET because they have trouble processing glucose and it means keeping blood sugar or insulin levels under control for the exam.

[url]http://www.stonybrookmedicalcenter.org/lcec/diabetic

Role of FDG PET/CT in Staging of Recurrent Ovarian Cancer

[url]http://radiographics.rsna.org/content/31/2/569.full.pdf
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Old 11-15-2011, 01:03 PM
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Default Magnetic Resonance Imaging (MRI scan)

By: Peter F. Ullrich, Jr., MD

The MRI (Magnetic resonance Imaging) was developed in the 1980’s and has revolutionized treatment for patients with low back pain. An MRI scan is generally considered to be the single best imaging study of the spine.

Physicians usually have a good idea of what they are looking for on the MRI scan before one is performed. The scans are most commonly used for pre-surgical planning, such as for a decompression or a lumbar spinal fusion. MRI scans are extremely sensitive to picking up information about the health of the discs, as well as the presence of any tumors or a lumbar disc herniation pinching the nerve roots.

In addition to pre-surgical planning, MRI scans are also very useful for the following:

To rule out infection or tumor

For patients who have had surgery, to differentiate scar tissue from a recurrent disc herniation.

Prior to performing an epidural injection to rule out the risk of injecting a steroid into a tumor or infection

An MRI scan is not the best diagnostic study to assess a fracture. A computerized Tomography (CT scan) is generally done for patients who have suffered some trauma (such as a fall) if a fracture is suspected.

The MRI works by rotating a magnet around a patient, which changes the excitation level of hydrogen atoms in the body. When the hydrogen atoms revert back to their normal level of excitation, they emit a slight amount of radiation that is then picked up on a scanner.

The developed image shows anatomy by differentiating between tissues that have a lot of water (such as fat, cerebrospinal fluid or discs) and tissues that do not have much water (such as bone, cartilage, and nerve roots).

If you have low back pain and/or leg pain and are wondering if you should get an MRI scan to see what is causing the pain, the following general rules explain when a scan is useful and when it is not useful:

Important considerations for an MRI scan:

There are a number of important factors to take into consideration for an MRI scan, including limitations with interpretation of findings and the timing of when an MRI scan should be performed.

First, the difficulty with the results of an MRI scan, as with many other diagnostic studies, is that the "abnormality" that shows up on the MRI scan may not actually be the cause of pain. Numerous clinical studies have shown that approximately 30% of individuals in their thirties and forties have a lumbar disc herniation on their MRI scan, although they do not have any pain.

Therefore, an MRI scan cannot be interpreted on its own. Everything seen on an MRI needs to be well-correlated to the individual patient’s situation, including:

Symptoms (such as the duration, location, and severity of pain)

Any neurological deficits on their physical examination

Another important consideration with MRI scans is the timing of when the scan is done. The only time an MRI scan is needed immediately is when a patient has either:

Bowel or bladder incontinence

Progressive weakness in the legs due to nerve damage.

Fortunately, both of the above situations are rare.

When patients have predominantly leg pain and a lumbar disc herniation is suspected, MRI scans are usually recommended early in a patient’s course of pain. This is because surgery for a lumbar disc herniation generally carries few unwanted side effects (morbidity) and leads to an early return to normal function for the patient.

When patients have primarily low back pain, generally the only surgical treatment available is a lumbar spinal fusion. This type of surgery does carry a reasonable amount of unwanted aftereffects (morbidity) and a longer healing time. Therefore, physicians often recommend waiting 3 to 6 months (after the onset of pain) before having an MRI scan done in order to see if the pain will get better with conservative treatments.

As a very general rule, if the results of the MRI scan are not going to affect a patient’s further treatment and patient will continue with non-surgical treatments such as chiropractic treatments, physical therapy and medications, waiting to obtain a scan in most situations is a reasonable option.

Indications and contraindications for an MRI scan:

The following general rules are usually considered by a physician before ordering an MRI scan for a patient.

Indications include:

After 4 to 6 weeks of leg pain, if the pain is severe enough to warrant surgery.

After 3 to 6 months of low back pain, if the pain is severe enough to warrant surgery.

If the pain is accompanied by constitutional symptoms (such as loss of appetite, weight loss, fever, chills, shakes, or severe pain when at rest). These symptoms may indicate that the pain is due to a tumor or an infection.

For patients who may have lumbar spinal stenosis and are considering an epidural injection to alleviate painful symptoms.

For patients who have not done well after having surgery, if their pain symptoms do not get better after 4 to 6 weeks.

Contraindications include:

Patients who have a heart pacemaker may not have an MRI scan

Patients who have a metallic foreign body (metal sliver) in their eye, or who have an aneurysm clip in their brain, cannot have an MRI scan since the magnetic field may dislodge the metal.

Patients with severe claustrophobia may not be able to tolerate an MRI scan, although more open scanners are now available, and medical sedation is available to make the test easier to tolerate.

Patients who have had metallic devices placed in their back (such as pedicle screws or anterior interbody cages) can have an MRI scan, but the resolution of the scan is often severely hampered by the metal device and the spine is not well imaged.

If a patient's symptoms match the indications for an MRI scan, and there are no known risk factors (contraindications), then an MRI scan can potentially be very beneficial in helping plan further treatment.
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Old 11-15-2011, 01:05 PM
gdpawel gdpawel is offline
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Default Do I need an MRI?

An MRI is a completely different technology from an x-ray and CT scan and represents the single most useful imaging study available for spine surgery.

It is particularly useful as an aid in the assessment of certain conditions by providing detail of the disc (such as for degenerative disc disease, isthmic spondylolisthesis) and nerve roots (such as for lumbar disc herniation, lumbar spinal stenosis). MRI scans are also useful to rule out tumors or spinal infections.

An MRI images the spine by using a magnet that goes around the body to excite hydrogen atoms. After the atoms return to their normal level of excitation, they emit energy that is picked up on a scanner. Since humans are composed primarily of water (which is two parts hydrogen), MRI's provide highly refined detail of the spine's anatomy.

Unlike an x-ray beam, there is no radiation with the magnet so the scans may be done for pregnant women. However, patients with a pacemaker implanted in their heart should not have a scan because the magnetic field will cause the pacemaker to malfunction. Also, anyone who works around metal should first have an x-ray of their eye sockets to ensure that they do no have any metal filings in their eyes, which the magnetic field may cause to migrate and damage the eye.

Because most scanners are fairly tight, certain patients may feel uncomfortable, or may not tolerate, lying in a tight tunnel for 45 to 60 minutes while the scan is being performed. To address this issue, newer generation scanners are designed with more open space, although a more open tube does sacrifice the excellent detail provided by the tight tubes.

How much does an MRI cost?

[url]http://clearhealthcosts.com/blog/2012/11/how-much-does-an-mri-cost-part-1/
[url]http://clearhealthcosts.com/blog/2012/11/how-much-does-an-mri-cost-part-2/

Cancer Detection With MRI As Effective As PET-CT Scan, But With Zero Radiation Risks

As a way to avoid heavy radiation exposure during cancer detection, scientists from Stanford University’s School of Medicine and Lucile Packard Children’s Hospital have demonstrated that MRI-based imaging techniques are just as effective as conventional scanning methods, but bring none of the risks.

Finding cancerous tumors before they spread is a critical part of the disease’s prevention. Unfortunately, one of the most effective ways to find them is to send radioactive tracers swimming through the body, as part of PET-CT scan, exposing patients to the equivalent of 700 chest X-rays. Among children especially, whose bodies and brains are still developing, high-level exposure to radiation could lead to secondary forms of cancer later in life. This risk-reward dilemma prompted the team to investigate the safety and effectiveness of MRI-based approaches, which mimic a PET-CT scan’s results, but bear none of the costs.

"I'm excited about having an imaging test for cancer patients that requires zero radiation exposure," said senior author of the study, Dr. Heike Daldrup-Link, associate professor of radiology at Stanford and a diagnostic radiologist at the hospital, in a statement. "That is a big deal."

Traditional PET-CT (positron emission tomography-computed tomography) scans utilize the dual power of the PET scan, which locates a radioactive isotope injected into a patient’s desired tissues, and a CT scan, which produces a 3-D model of the body via X-rays. In the team’s current study, involving 22 patients ages 8 to 33 who had lymphoma or sarcoma, PET-CT scans found 163 of 174 total tumors.

Meanwhile, some research suggests that one PET-CT scan exposes a person to the same amount of radiation that employees who work with radiation directly can safely be exposed to in a year. And while the risk of cancer arises at levels five times that amount, experts fear that early exposure in life increases a child’s risk for cancer, particularly as they have many years left to develop it. Daldrup-Link and her colleagues sought to solve this problem with MRI-based techniques.

"Some type of whole-body MRI imaging test is available at many big children's hospitals right now," Daldrup-Link said, adding that hesitant doctors have remained withdrawn because of a lack of confidence. "It's slowly entering clinical practice, but clinicians are cautious and want to be convinced.”

The team hopes their current study changes that, as the MRI scans found 158 of 174 total tumors. As opposed to an injectable tracer that courses through the patient’s body, these scans work via a contrasting agent made up of iron nanoparticles. The nanoparticles stay in the body for many days, and when scanned, reveal blood vessels as brighter and important organs and components, such as livers, spleens, and bone marrow, as darker — providing a contrast to see tumors in greater relief. The U.S. Food and Drug Administration has approved the nanoparticles to treat anemia, and the team received permission for experimental use.

Overall, the two methods produced similar levels of sensitivity, specificity, and diagnostic accuracy. Despite a small risk of allergic reaction to the nanoparticles' coating, the MRI scans yielded no negative side-effects among subjects. With their latest success, the team has plans for future research to encompass all aspects of cancer treatment, from early stages to later stages that includes a broader pool of patients with more diverse forms of the disease.

"It's really exciting that this will soon be clinically applicable," Daldrup-Link said.

Source: Klenk C, Gawande R, Uslu L, et al. Ionising radiation-free whole-body MRI versus ¹⁸F-fluorodeoxyglucose PET/CT scans for children and young adults with cancer: a prospective, non-randomised, single-centre study. The Lancet. 2014.
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Last edited by gdpawel : 06-26-2014 at 12:47 AM. Reason: Additional info
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Old 02-08-2012, 01:41 PM
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Default CMS/ACRIN Collaborative Trial on PET Scans

There was a large collaborative trial in 2006, with CMS (Centers for Medicare and Medicaid Services) and ACRIN (American College of Radiology Imaging Network) to gather data shared with CMS gleaned from the National Oncologic PET Registry (NOPR), what was thought to determine "efficacy" of the PET scan in cancer treatment management. The results of that study showed that 36.5% of patients anticipated course of treatment was changed. Some thought that this was significant.

This was not "efficacy." Efficacy means that the use of the modality in question (lab test, radiographic test, whatever) improves clinical outcomes, compared to patient management in the absence of such testing. The alternative to getting a PET scan is to rely on the use of much less expensive imaging (CT scan, MRI, ultrasound, plain X-rays, etc.) or just to manage patients on the basis of history and physical examination.

If patients were managed only on the basis of less expensive imaging studies, the clinical outcomes would be so identical that it would take a 100 million dollar study in 20,000 patients to begin to show the hint of a difference.

All the CMS/ACRIN data showed is that the doctors pay attention to the test results. If a study was made, like this, on whether patients anticipated course of treatment were changed in cases where cell culture assay testing were ordered, you'd find that the treatment would be changed in more than 40% of cases.

Even in the underpowered Cree, et al study, the use of the ATP assay changed treatment decisions in something like 90% of the cases, but the study was too small to show that the changed treatment decisions were to the benefit of the patient, in terms of longer survival. The study allowed the physician's choice arm to include Dr. Cree's own drug combination as the trial accrued (BMC Cancer. 2003; 3:19).

The "bar" is very low for PET because it benefits clinical researchers (e.g. ASCO leadership) and is a convenience to doctors (who only have to write an order) and makes a lot of money for institutions which provide it. It's never been shown that the use of PET results in patients live longer. The use of PET, in most cases, has negligible impact on ultimate clinical outcomes.

Efficacy doesn't mean proof that treatment decisions are changed; efficacy means that you prove that patient "outcomes" are improved as a result of the changed treatment decisions. It hasn't been proven to improve outcomes and that is what is meant by "efficacy" in this context.
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Old 02-08-2012, 01:52 PM
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Default CMS Covers Majority of PET Scans for Medicare Cancer Patients

The move by the Centers for Medicare and Medicaid Services (CMS) to cover positron emission tomography (PET) scans for the majority of Medicare cancer patients nationwide is based upon significant clinical evidence regarding the effectiveness of PET for the management of patients with cancer gleaned from the National Oncologic PET Registry (NOPR) which is co-managed by the ACR and ACRIN.

”Expanded CMS coverage for PET is a tremendous step forward for cancer care in this country. The NOPR is a shining example of how the medical community can interact with government on research that can ultimately save and extend patients’ lives,” said James H. Thrall, M.D., FACR, chair of the ACR Board of Chancellors, Radiologist-in-Chief, Massachusetts General Hospital, and Professor of Radiology, Harvard Medical School.

PET scans for many cancers were previously reimbursed only if the facility submitted data to the NOPR registry. Now, Medicare patients with essentially all cancers can receive Medicare coverage for at least one PET scan prescribed by their physicians for initial treatment strategy evaluation. In addition, PET is also now covered for 11 cancer types for subsequent treatment strategy evaluation. These cancers are breast, cervix, colorectal, esophageal, head and neck, lymphoma, melanoma, non-small cell lung, thyroid, myeloma and ovary.

Patients with these cancers represent the vast majority of cancer patients in the Medicare system. For all other cancers, PET coverage for subsequent treatment strategy evaluation requires participation in an approved Coverage with Evidence Development (CED) program. The NOPR can, with planned modifications, continue to serve this function for those PET studies still requiring CED.

“NOPR data undoubtedly served a primary role in this CMS decision, which will allow seniors far greater access to PET imaging to guide their care. The registry provided undeniable evidence that PET scans can serve a vital role in diagnosing, staging, restaging and monitoring treatment for patients with many types of cancer. We are proud that NOPR efforts have enabled CMS take this very important step to help cancer patients nationwide,” said Barry Siegel, M.D., FACR, chair of the ACRIN PET Imaging Core Laboratory, co-chair of the NOPR working group, and professor of radiology and chief of Nuclear Medicine at the Mallinckrodt Institute of Radiology in St. Louis.

Studies published in the Journal of Clinical Oncology the Journal of Nuclear Medicine and Cancer analyzed data from more than 41,000 NOPR cases and found that results of PET scans led to an intended change in cancer management of nearly 40 percent of patients. Approximately 10 percent of all Medicare covered PET scans in 2007 were performed under the auspices of the NOPR.

“For a great many patients, who would otherwise have to pay out-of-pocket for their PET scans, this CMS decision will save thousands of dollars. It will also allow more providers to offer this life-saving care to our nation’s seniors,” stated R. Edward Coleman, M.D., member of the NOPR working group, former chair of the ACR Nuclear Medicine Guidelines and Standards Committee, and chief of Nuclear Medicine at Duke University Hospital.

The NOPR was launched in May 2006. The ACR and ACRIN worked to develop the NOPR in collaboration with registry sponsor, the Academy for Molecular Imaging since CMS announced its intent to support a PET registry in January 2005. The American Society of Clinical Oncology and the Society for Nuclear Medicine also have played key roles in guiding the project’s development.

FDG-PET, also called PET imaging or PET scan, is a test that images the function of cells to show differences between healthy tissue and diseased tissue. It uses a small amount of a radioactive chemical which is combined with sugar. This combination is called FDG, so the test is sometimes called an FDG-PET scan. It is used to evaluate various neurological and cardiac disorders, as well as for diagnosing, staging, and monitoring the treatment of many different cancers.

CMS National Coverage Determination [url]http://www.cms.hhs.gov/mcd/viewdecisionmemo.asp?from2=viewdecisionmemo.asp&id

Note: From NCD to LCD determination

CMS is ending its requirement for coverage with evidence development for fluorodeoxyglucose positron emission tomography (FDG-PET) in oncology. In Pet scanning for solid tumors, the agency removed the requirement for prospective data collection by NOPR and will now cover only three scans after the completion of initial therapy.

Coverage of any additional FDG-PET scans used to guide subsequent management will be determined by local Medicare contractors. America's Health Insurance Plans stated that there is inadequate evidence to justify coverage of any post-treatment scans. Avalere Health noted that subsequent scans should not be evaluated by local Medicare Administrative Contractors because of increased administrative burden
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Last edited by gdpawel : 06-16-2013 at 11:31 AM. Reason: additional info
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Old 03-05-2012, 01:02 AM
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Default Primer on Pet Scans

PET stands for “positron emission tomography”, and a PET scan is a procedure designed to identify abnormal cellular activity that might indicate cancer. A prominent use for the PET scan (or combination PET/CT) is in achieving accurate staging of cancer.

In a PET scan, the patient is injected with a glucose-based tracer substance: think of it as a “hot sugar” . The PET scan picks up where this sugar localizes in the body. The idea in use for oncology is that the cancer cells, because they’re very active, eat up more sugar than non-cancerous cells and so the cancer cells will collect this tracer and will appear brighter on the scan than normal tissue.

PET scan results are reported in “SUV” units, in which SUV stands for “standardized uptake value”. The SUV is just a measure that indicates how bright the tissue is on the scan; that is, how much cellular activity is occurring in that area. This activity can represent various things, from inflammation to infection to cancer. There is no threshold SUV number that distinguishes cancer from inflammation or infection, but higher numbers (especially in the high single digits or more) are most suggestive of cancer.

PET scans are very sensitive (finding abnormality when one exists), but not perfectly specific, meaning that they can be positive for things other than cancer. In reviewing the PET scan, medical personnel look for the shape and location of the abnormal activity as well as the SUV number.

Most cancer types (e.g., lung, breast, colon) show up well on PET scans. Certain cancers (e.g., renal cell) are not seen as well with the PET scan. Some areas of the body (e.g., heart, brain, sometimes the bowels) normally have a significant glucose uptake/metabolic activity anyway, soincreased SUV numbers in those areas are of less concern than high activity in other areas. Given this activity, other types of scans (e.g., MRIs) might be more useful than PET scans for imaging certain tumors (e.g., brain tumors).

Some studies have supported a correlation of cancers with higher uptake (maximum SUV) being associated with a more aggressive clinical behavior, or conversely, low PET uptake with a more indolent clinical behavior of the cancer. In addition, though PET scans are not a standard imaging test for assessing response to therapy (compared with the far more established CT scan), some research suggests that PET scans may provide early feedback about the clinical benefit of lack of benefit from a systemic therapy. However, PET scans also tend to pick up inflammation in the area of recent prior surgery or radiation and are therefore well known to be very difficult to interpret in that setting.

Source: Cancergrace.org
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Last edited by gdpawel : 09-19-2012 at 06:28 PM. Reason: spelling errors
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Old 06-13-2012, 12:08 AM
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Default Use of Diagnostic Imaging Studies and Associated Radiation Exposure

A study in the Journal of the American Medical Association found that the number of MRIs quadrupled, CT scans tripled and PET scans went up 57 percent between 1996 and 2010. The researchers tracked up to 2 million members of six large health systems in the U.S.

Magnetic Resonance Imaging (MRI) uses magnets and radio frequency fields to scan the body and help doctors make diagnoses of tumors, torn ligaments or strokes without surgery. A PET, or positron emission tomography, scan can be conducted alone or combined with MRI with radioactive isotopes to show metabolic activity in the body such as cancer.

“The increase in use of advanced diagnostic images has almost certainly contributed to both improved patient care procedures and outcomes, but there are remarkably few data to quantify the benefits of imaging,” radiology professor and lead author Dr. Rebecca Smith-Bindman from the University of California, San Francisco, and her colleagues write.

Americans spend an estimated $100 billion a year on medical imaging. For each patient, each procedure can cost between a few hundred and several thousand dollars. Usually doctors order them for the best of reasons, but sometimes it is defensive medicine based on the fear of lawsuits or, even worse, the need to amortize the huge cost of a piece of equipment the practice has purchased.

Another major downside of increased imaging is the “false positive,” which is the discovery of a growth or other apparent problem that presents no danger but needs to be removed -- with additional cost and anxiety.

The biggest danger with scanning comes from CT, or computed tomography. A CT scan exposes the patient to huge amounts of X-rays. One CT scan of the chest zaps a patient with the same amount of radiation as 150 old-fashioned X-rays. In their survey of medical records, the authors of the study found that 3.9 percent of patients were receiving an exposure or more than 50 millisieverts every year. In comparison, that is about the equivalent of the one-time amount that the Japanese government estimates that the nearby residents of the Fukushima power plant got in the hours before they evacuated.

A recent Institute of Medicine report on risk factors for breast cancer listed chest CT scans high on the list. An international study found that children who get CT scans have a slightly higher risk of later developing leukemia and brain cancer. While the absolute risk of cancer is still small, the British researchers suggested minimizing radiation exposure as much as possible.

JAMA. 2012;307(22):2400-2409. doi:10.1001/jama.2012.5960

Use of Diagnostic Imaging Studies and Associated Radiation Exposure for Patients Enrolled in Large Integrated Health Care Systems, 1996-2010

Rebecca Smith-Bindman, MD; Diana L. Miglioretti, PhD; Eric Johnson, MS; Choonsik Lee, PhD; Heather Spencer Feigelson, PhD, MPH ; Michael Flynn, PhD; Robert T. Greenlee, PhD, MPH; Randell L. Kruger, PhD; Mark C. Hornbrook, PhD; Douglas Roblin, PhD; Leif I. Solberg, MD; Nicholas Vanneman, MA; Sheila Weinmann, PhD; Andrew E. Williams, PhD

Abstract

Context: Use of diagnostic imaging has increased significantly within fee-for-service models of care. Little is known about patterns of imaging among members of integrated health care systems.

Objective: To estimate trends in imaging utilization and associated radiation exposure among members of integrated health care systems.

Design, Setting, and Participants: Retrospective analysis of electronic records of members of 6 large integrated health systems from different regions of the United States. Review of medical records allowed direct estimation of radiation exposure from selected tests. Between 1 million and 2 million member-patients were included each year from 1996 to 2010.

Main Outcome Measure: Advanced diagnostic imaging rates and cumulative annual radiation exposure from medical imaging.

Results: During the 15-year study period, enrollees underwent a total of 30.9 million imaging examinations (25.8 million person-years), reflecting 1.18 tests (95% CI, 1.17-1.19) per person per year, of which 35% were for advanced diagnostic imaging (computed tomography [CT], magnetic resonance imaging [MRI], nuclear medicine, and ultrasound). Use of advanced diagnostic imaging increased from 1996 to 2010; CT examinations increased from 52 per 1000 enrollees in 1996 to 149 per 1000 in 2010, 7.8% annual increase (95% CI, 5.8%-9.8%); MRI use increased from 17 to 65 per 1000 enrollees, 10% annual growth (95% CI, 3.3%-16.5%); and ultrasound rates increased from 134 to 230 per 1000 enrollees, 3.9% annual growth (95% CI, 3.0%-4.9%). Although nuclear medicine use decreased from 32 to 21 per 1000 enrollees, 3% annual decline (95% CI, 7.7% decline to 1.3% increase), PET imaging rates increased after 2004 from 0.24 to 3.6 per 1000 enrollees, 57% annual growth. Although imaging use increased within all health systems, the adoption of different modalities for anatomic area assessment varied. Increased use of CT between 1996 and 2010 resulted in increased radiation exposure for enrollees, with a doubling in the mean per capita effective dose (1.2 mSv vs 2.3 mSv) and the proportion of enrollees who received high (>20-50 mSv) exposure (1.2% vs 2.5%) and very high (>50 mSv) annual radiation exposure (0.6% vs 1.4%). By 2010, 6.8% of enrollees who underwent imaging received high annual radiation exposure (>20-50 mSv) and 3.9% received very high annual exposure (>50 mSv).

Conclusion: Within integrated health care systems, there was a large increase in the rate of advanced diagnostic imaging and associated radiation exposure between 1996 and 2010.

[url]http://jama.jamanetwork.com/article.aspx?articleid=1182858

A doctor talks about: Radiation risk from medical imaging

[url]http://www.health.harvard.edu/newsletters/Harvard_Womens_Health_Watch/2010/October/radiation-risk-from-medical-imaging
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Gregory D. Pawelski

Last edited by gdpawel : 02-16-2014 at 07:23 PM. Reason: additional info
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Old 06-13-2012, 02:32 PM
gdpawel gdpawel is offline
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Default Hazards of CT Scans

The Archives of Internal Medicine reported on two studies estimating that the radiation exposure from the 72 million CT scans ordered in 2007 alone will result in 15,000 additional cancer deaths twenty to thirty years down the road.

An editorial in the Archives pointed out that there is an eight-fold difference in CT scan use around the country with no better outcomes where more scans are done.

Is there evidence that a CT saves lives? No. No diagnostic/laboratory test ever has. This is not what it does.

Diagnostic/laboratory tests are judged by accuracy and reproducibility and never by their effect upon treatment outcomes. Most tests used today have comparable "sensitivities" and "specificities."

CT scans were not approved because they saved lives in a controlled clinical trial that compared the outcome of patients who received care with or without the benefit of a CT scan. They were approved because their performance characteristics (sensitivity/specificity) are reproducible, favorable and provide information to treating physicians.

In cancer medicine, no test in oncology has ever been shown in prospective randomized clinical trials to improve patient outcomes. The existing standard has always been the "accuracy" of the test. This is true for every single test used in cancer medicine, from estrogen receptors to panels of immunohistochemical stains (IHC) to diagnosing and classifying tumor to Her2/neu and CA-125 to cell culture assays to MRI's, CT Scans, Pet Scans and so on.

Even when you get to the new genetic/molecular tests, the validation standard that private insurance companies is accepting is "accuracy" and not "efficacy." The essential "proof" is that all they have to do for these tests is that the test has a useful degree of "accuracy," not that the use of the diagnostic test improves clinical outcomes.

A cardiac CT provides anatomic information regarding the presence or absence of blockages in coronary arteries. Such findings alone do not determine whether or not a patient requires an invasive procedure such as an angiogram or angioplasty/stent. Such decisions should be based on physiologic indicators such as presence of angina or, more importantly, an abnormal stress test. A cardiac CT by itself will never be proven to save lives. However, it is yet another tool in the arsenal that must be used properly.

In cancer medicine, the CT is used to follow the size of the patient's tumor while the patient is receiving repeated courses of chemotherapy to determine whether or not the treatment is working and whether or not different drugs should be given, instead. This is an entirely unproven benefit, and were appropriate studies ever to be performed, there wouldn't be any measurable benefit at all, in terms of improving patient response to chemotherapy or patient survival with chemotherapy.

CT Scans and Cancer Risk: Been There, Done That

[url]http://www.cancer.org/AboutUs/DrLensBlog/post/2009/12/15/CT-Scans-and-Cancer-Risk-Been-There-Done-That.aspx

Projected Cancer Risks From Computed Tomographic Scans Performed in the United States in 2007

These detailed estimates highlight several areas of CT scan use that make large contributions to the total cancer risk, including several scan types and age groups with a high frequency of use or scans involving relatively high doses, in which risk-reduction efforts may be warranted.

[url]http://www.cancer.org/AboutUs/DrLensBlog/post/2007/11/29/How-Dangerous-Are-CT-Scans.aspx

Radiation Dose Associated With Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer

Radiation doses from commonly performed diagnostic CT examinations are higher and more variable than generally quoted, highlighting the need for greater standardization across institutions.

[url]http://archinte.ama-assn.org/cgi/content/short/169/22/2078?home
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Gregory D. Pawelski

Last edited by gdpawel : 03-29-2014 at 08:46 PM. Reason: additional info
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