Doctor insights on:
Difference Between Pet Scan And Ct Scan
Metabolism & Anatomy: A pet scan is use to evaluate metabolic processes in your body. Currently pet scans are most commonly use to evaluate the glucose metabolism to assess the activity of neoplasms by capturing gamma photons. For this purpose a radioactive form of sugar is injected in the patient. In ct scans external x-rays are use to produce an anatomic image of the body to evaluate size, shape, etc. ...Read more
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
Metabolism / Anatomy: A pet scan is an image study that assess glucose metabolism for different tissues in your body using gamma photons while a ct scan is an anatomic picture of your body that reveals size, shape and intensities of organs using x-rays. Pet scans have several indications, including: cancer, cognitive disorders and heart perfusion stress and viability. ...Read more
Sorry to be so vague. They are very different in what can be seen and what can be diagnosed. Not enough room to go through the details. The Internet has many resources for this information. Try this one:
http://www. Radiologyinfo. Org/ ...Read more
Imaging tests: Ct uses radiation, like multiple x-rays. Mri uses magnets, and is very useful in characterizing soft tissue differences such as in the brain or joints, but also is more expensive and takes much more time. Pet is typically used for cancer imaging as it detects glucose usage by tissue (which is greater in tumors). Bone / gallium uses radiotracer. Best I can explain in 400 letters! ...Read more
Anatomy vs Physiolog:
Mri and ct scans are typically looking at the anatomy of a patient, as well as differences in blood flow if contrast is administered.
Pet, bone and gallium scans are all looking at the function, or physiology of the patient, and the anatomy is of secondary concern. For example, pet scans are usually using f-18 fdg, a glucose analog, and display differences in glucose use, a main energy source. ...Read more
Anatomy / metabolism: CAT scan utilizes xrays for determination of anatomical structures in multiple planes coronal, sagittal, and transaxial. PET scan uses radioactivity with tracer FDG 18 a glucose metabolite to show metabolic areas. Usually malignant lesions are most active. Small metastatic lesions can be detected. Sometimes compared with anatomy with PT CT. ...Read more
My father has metastatic melanoma, 1 lymph node involvement. Pet scan and CT scan shows no other metastasis at this time. Does this mean he is cured?
Melanoma...: Melanoma is a very tricky disease and must be followed closely. It can metastasize to odd places. It is good news that only 1 lymph node is seen on pet/ct rather than many lymph nodes but one should note that micrometastases or very small lesions may be below the resolution of pet imaging. ...Read more
Anatomic/physiologic: Pet scan involves intravenous injection of radio tracer usually f18 fdg.Imaging of whole body occurs for localization of areas of increased glucose metabolism. Malignant tumors usually most active.Ct scan involves x-ray and performs anatomic imaging of parts of body usually head, chest, abdomen, pelvis, or extremities. Pet? Ct combines imaging modalities for anatomic localization of areas of uptake. ...Read more
When having a pet scan, is the CT scan that used in conjunction good enough to diagnose all tumors?
Good but not all: It is good to have ct in conjunction with pet scan because ct provides more resolution. It helps the radiologist correlate signals seen on pet scan with actual anatomy precisely. However, no test is perfect, so pet/ct is not able to diagnose all tumors. But pet/ct can diagnose many types. ...Read more
Both: The actual diagnosis of lymphoma requires tissue, usually excisional biopsy of an entire lymph node. Staging to see where other sites of disease could be is done with a combined PET/CT. The staging used to matter more many years ago when they would often give XRT or do surgery, it doesn't matter as much as it used to because almost everybody gets systemic chemotherapy for both Hodkins and non H ...Read more
Not the same: Ct scan will tell you the anatomy -whether there is a mass, nodule, lymph nodes, scars etc. Pet scan will tell you about the function /metabolism of the cells. Cancer cells have rapid turnover time thus it would uptake more sugar -resulting in " glowing" on the pet scan on the area with increased metabolism-like in cancerous area, or infection. Adding pet to ct scan will give more information. ...Read more
If I've had a CT scan of mu lungs and there was a subpleural nodule found 6mm should I get a pet scan? And could this be cancerous?
PET in cancer: PET scans are used to detect areas of abnormally increased metabolism, while CT scans only detect areas of differing density or lucency to radiation. So an abnormality like an area of scarred old tumor might look abnormal on CT scan but not have increased metabolism indicating active cancer on PET scan. False positives still occur with both, but they tend to commplement each other. ...Read more
Ct scan found mass on pancreas, adnocarcinoma in acities. Pet scan found no masses. Doctors said they are confused. What could this be?
Mass: Have an endoscopic ultrasound to look at the pancreas and biopsy any suspicious areas seen. This is the best test. ...Read more
Radiology - in sclc is the primary tumor normally difficult to see on a CT scan? Heard that often only spread to nodes can be seen. Pet scan better?
Small Cell Lung Ca:
SCLC does metastasize early, often to nodes, which are often the presenting finding. Usu. The primary tumor is small even though symptoms have occurred.
CT has very high resolution so it has the best chance to find it, esp. If pt. Has been followed with serial screening CTs based on risk factors like smoking history.
PET is useful to find mets, but not a small primary.
CT scan showed 0.7cm sub pleural noncalcified nodule along left hemidiaphragm. Should I monitor with normal CTs in 2-3 months or PET scan now?
How often do you need to use PET scan or bronchoscope to locate lung cancer because it does not show on CT scan but symptoms tell you to keep looking?
Clinical judgement: This pathologist is underwhelmed with the health or public benefits of intensive screening for tiny lung cancers. I'd hope that if the person is symptomatic, some other investigations are undertaken and the actual cause gets found. ...Read more
My dad is 53 years old and in good shape. He was diagnosed with stage 4 secondary liver cancer; the primary is still unknown. He has had a CT scan, an endoscopy, and a colonoscopy done. Will a pet scan show something more?
High parathyroid related peptide and hypercalcemia with elevated ACE in 12 yr old. Clear pet scan, CT scan and bone marrow. On prednisone to control.
Glucose metabolism: PET with F18 FDG, glucose metabolite, determines glucose metabolism of normal and abnormal structures. For example, sometimes lymph nodes are visualized on CT and do no know whether benign or malignant. In general malignant lesions are more active and have higher metabolism of glucose ...Read more
Can you explain results of chest X-ray led 2 cat scan, which led 2 pet scan. Results are multiple nodules. What causes lung nodules?
Multiple: There are many causes for pulmonary nodules, which can be broken down into benign or malignant. There are a large number of causes for benign nodules, and 95% of nodules seen on CT scan are benign. If the nodule is large enough, a biopsy may be recommended. The initial move is to see if the same mass was present on a previous scan. PET scans are used to add information, but should not be done firs ...Read more
Many differences: Mri (magnetic resonance) does not utilize ionizing radiation (ir) characterize tissues, extent of tumor, infection, damage to cartilage/ligaments. Ct (ir) can localize traumatic changes, tumors, appendicitis, kidney disease. Pet/ct (ir) combo isotope /ct finds subtle metastases and recurrent malignancy, ...Read more
There are differences in techniques between the ct scan with a pet scan and a general ct scan. Additionally, radiologists may measure a nodule slightly differently.
Please look at a ruler and realize just how small 1 mm is. Radiologists routinely are measuring things less than 1 cm or about 3/8 of an inch. ...Read more
A PET scan with contrast shows changes at the molecular level. So, why is it that a lesion larger than 2 cm's did not show up at all on a CT?
Very unlikely: You need to talk with your own md about this. It would take a lot of scans. . ...Read more
Different mechanisms: Mri uses magnetic radiation (no x-ray) for anatomic localization and characterization of different parts of body, water and fat constitution of different tissues. Ct uses x-ray to characterize anatomy of body, better for bone than mr. Pet, bone, gallium scans use radio tracers intravenously. Petglucose metabolism of tumors, gallium (infection/tumor), bone scan for fxs, tumors, infection bone metabolism. ...Read more
A Ct looking for PE, had incidental nodules finding in rt hiler. A 3.5 mass, Pet Scan suggests malignancy and Bronchoscope showed no cancer? Now what?
Ct uses xrays taken an 360 degrees combined with a computer to see"inside" the body. The table moves as the xray tube and detectors spin around the patient 10 times a second or more! The image shows excellent soft tissue detail, enhanced with injection of intravenous contrast or oral contrast. This way the body is shown in slices, in any plane, usually axially, but ...Read more
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