Reasons for a false positive pet scan - Doctor answers

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Following cancer surgery I had 2 clear pet scans. Now after 5 yrs the pet scan is abnormal. What can be the reason, what to do?

Following cancer surgery I had 2 clear pet scans. Now after 5 yrs the pet scan is abnormal. What can be the reason, what to do?

Abnormal PET....: It is difficult to say without knowing your exact history. What type of cancer was it? Was the pet performed at the same institution and interpreted by the same person? Abnormal pet could mean recurrence but without the report it is difficult to say. There are many causes of false positive on pet. Please look further into this calmly and discuss with your doctor to understand the details. ...Read more

Dr. Guido Davidzon
291 Doctors shared insights

Pet Scan (Definition)

Pet scans most often use a radioactive form of glucose, the energy source for most of the cells in our bodies. The pet scanner can detect and measure how much of the radioactive glucose analog, f-18 fdg, is in a particular organ or region. The areas using more glucose are hyper metabolic and generally more worrisome. Our brains and sometimes hearts prefer glucose as food, making ...Read more


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False positive stress test reason?

False positive stress test reason?

Body habitus: Most common cause of false positive stress test is body habitus. This commonly affects women because the heart rhythm needs to be picked up through their breast tissue. ...Read more

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Is it possible to get a false positive herpes culture test? How often does it occur? What is the reasoning for it?

Is it possible to get a false positive herpes culture test? How often does it occur? What is the reasoning for it?

Rarely if ever: False positive results are very unlikely for HSV culture. If the test was actually a DNA test (PCR test), there is a slightly higher chance of false pos, but still very unlikely. If you have had a positive culture or PCR, for sure you have herpes at whatever site was tested (genital, oral). But if a blood antibody test, not culture or PCR, false positive results are quite common. Good luck. ...Read more

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If an ovarian cyst gave a false positive last yr and I've taken 3 tests last week and all r pos, could a cyst be the reason why again?

If an ovarian cyst gave a false positive last yr and I've taken 3 tests last week and all r pos, could a cyst be the reason why again?

Preg test: I assume you are referring to a positive pregnancy test. If 3 tests report positive results then you need to see a doctor and determine if you are pregnant. Do not assume it is due to a cyst. If you are sexually active at all it could be a pregnancy. ...Read more

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Hi, my boyfriend tested positive for oxazepam but has never taken it in his life. Could a sleep aid or even tramodol be a reason for a false positive?

Hi, my boyfriend tested positive for oxazepam but has never taken it in his life. Could a sleep aid or even tramodol be a reason for a false positive?

False positives: Are very common when it comes to drug screening. Gas chromatography and mass spectrometry, however, don't lie. Ask to have the sample sent for definitive testing. ...Read more

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Why is HIV PCR used to test blood at blood banks, babies and acute HIV symps but not as a diagnosis? Other than cost and false positive what could be the reason that some docs don't trust it? Thanks

Why is HIV PCR used to test blood at blood banks, babies and acute HIV symps but not as a diagnosis? Other than cost and false positive what could be the reason that some docs don't trust it? Thanks

PCR is a. .: ..complex test, & more technically difficult to perform accurately than the antibody tests. Because PCR detects viral-RNA (proteins within the HIV virus) it is positive early in the course of infection & is used to try to confirm/exclude HIV as a diagnosis for a set of symptoms. You are correct that there are more false positives with PCR than with antibody tests. Antibody tests are gold standard ...Read more

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Is genital herpes a reason to produce a false positive ELISA HIV test?

Is genital herpes a reason to produce a false positive ELISA HIV test?

Asked and Answered: No. Absolutely not. But there is a link. Having hsv 2 makes your risk of contracting HIV five times higher than those without hsv 2. ...Read more

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Which is better, pet scan or cisternogram? Father already had a cisternogram results borderline positive. Should pet scan be done or repeat cisterno

Which is better, pet scan or cisternogram? Father already had a cisternogram results borderline positive. Should pet scan be done or repeat cisterno

Different tests: Cisternography is used to determine if there is normal pressure hydrocephalus. It looks at the flow of CSF fluid.

Pet scans are for looking at the brain cells and associated pathology. ...Read more

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Thyroid from 4cm to 7.1cm. Uptake 20.5%/34%. Fnb significant # multinucleated giant cells with positive pet scan prior to surgery 4 breast ca surgery?

Goiter: A goiter, size increased from 4 cm to 7.1 cm? Suspicious needle biopsy and positive pet scan? Possible breast cancer? You need consult with surgery and endocrinology. More information is needed, but likely you will benefit from thyroid surgery. The pathology exam will make diagnosis, and cancer is a concern. This is complicated, so take a friend with you for your consult. ...Read more

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What can a pet scan show?

What can a pet scan show?

What is the question: Currently pet scans are widely use for evaluation of glucose metabolism in the body.
In oncology, is use to for initial metabolic characterization of tumors, metastases as well as for treatment response and surveillance. In cardiology, pet scans are use to assess heart ischemia and viability and in neurology the study is use to evaluate cognitive disorders, epilepsy and brain tumors ...Read more

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Is it possible for pet scans to make a mistake?

Is it possible for pet scans to make a mistake?

Yes: Yes. As with all tests there can be some false positives and false negatives. If you think there may be a mistake you can always get a second opinion. ...Read more

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What are pet scans? What exactly is a pet scan?

What are pet scans? What exactly is a pet scan?

Positron Emission: These studies are done by injecting a special "dye" that is attached to a specific molecule. Most of the pet today is done using FDG (a glucose/sugar look-a-like molecule). Wherever this molecule is used/concentrated, the pet scan is brighter. Hence, tumors/infections (which use a lot of energy/sugar/fdg) are bright on such studies. More: http://en. Wikipedia. Org/wiki/positron_emission_tomography. ...Read more

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Can someone be with me while I have a pet scan?

Can someone be with me while I have a pet scan?

Probably: I would not recommend a child or pregnant woman be the companion. The amount of radiation dose is minimal to caretaker as long as has usual distance of 3.5 feet from patient. Study involves injection of isotope and sitting in quiet room for about 45 minutes. Then pet ct scan performed possibly for another half hour. Typical dose would be about 0.13 msv. Round-trip flight from new york to tokyo 0.13msv. ...Read more

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Are pet scans accurate or are other scans better?

Are pet scans accurate or are other scans better?

Depends: Depends on what you are looking for. PET scan usually uses a glucose based tracer to evaluate metabolic activity which can be increased in tumors. All modalities have a certain rate of false positives and negatives. Sometimes multiple modalities can each give you different information to obtain a complete evaluation. ...Read more

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What is the definition or description of: pet scan?

What is the definition or description of: pet scan?

Physiology of lesion: Pet scans most often use a radioactive form of glucose, the energy source for most of the cells in our bodies. The pet scanner can detect and measure how much of the radioactive glucose analog, f-18 fdg, is in a particular organ or region. The areas using more glucose are hyper metabolic and generally more worrisome. Our brains and sometimes hearts prefer glucose as food, making it hard to see. ...Read more

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How many pet scans can a person safely have in 2 months?

Depends: Radiation received from pet ct is relatively high compared to other imaging tests. Pet ct is mainly used for demonstrating metastatic disease, making decisions about effect of therapy, and looking for recurrence. Pet ct has helped prolong life because it can detect small lesions not seen by other tests. Wise decision should be made judging radiation risk versus positive benefit to the patient. ...Read more

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What is the difference between mris & pet scans?

What is the difference between mris & pet scans?

Anatomy vs Physiolog: Mri and ct look at the structure of the body, the anatomy, and the way diseases change or distort it.

Pet looks at the physiology, or how the body uses, or metabolizes something. For pet, the most common metabolism pathway looked at is how glucose is used. A low dose ct is often acquired at the same time as the pet (as in pet/ct scan), to correlate the pet findings with the ct anatomy. ...Read more

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Is pet scan can see previous stroke from 6 months ago?

Is pet scan can see previous stroke from 6 months ago?

Why PET?: Pet very valuable study to assess metabolic dysfnctn areas in brain due to many causes, and now we can inject newer chemicals to assess both alzheimer's and parkinson's, but really rather un-necessary and expensive test for stroke, as visualization readily available on an mri. ...Read more

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