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What is the need of PET-CT scan?


A PET-CT scan is a combination of a CT scan and a PET scan. The scan provides detailed information about patient cancer. Computed tomography takes a series of x-rays of the patient’s entire body and puts all together to create a three-dimensional (3D) image. A positron emission tomography (PET) scan is an imaging test that allows the doctor to check the diseases. The scan uses a special dye that contains radioactive markers. These markers are swallowed, inhaled, or injected into a vein in the patient’s arm, depending upon which part of the body is being examined by a doctor. The best Pet ct scan centre in bangalore provide this scan facility in less time or cost in an effective manner. When detected by a PET scanner, the tracers help the doctor see how well the patient’s organs and tissues are working. The tracer will accumulate in areas of higher chemical activity, which is useful because some tissues of the body and some diseases have a higher level of chemical movement. These areas of the disease will appear as dazzling spots in the PET scan. PET scanning can also measure blood flow, the use of oxygen, the way the human body uses sugar and much more. A PET scan is an outpatient process. That means that a patient can go day after the test ends.

Need for PET scan

A doctor may need a PET scan to inspect the patient’s blood flow, oxygen intake, or the metabolism of patient organs and tissues. PET scans show the various problems at the cellular level.

PET scans are used to detect:

• Cancer Disease
• Various heart problems
• Nerves system disorders(CNS)

1. Cancer Disease:- Cancer cells have a higher metabolic rate as compared to noncancerous cells due to this high level of chemical activity, cancer cells illustrate up as bright spots on PET scans. Because of this reason, PET scans are useful for detecting cancer and for:

• Checking if cancer has spread
• To test whether the cancer treatment is working or not
• Examination for a cancer recurrence

The doctor carefully analyses these examinations since it is possible that non-cancerous diseases resemble cancer on a scan. It is also possible for solid tumours not to appear on PET scans.

2. Various Heart problems:- PET scans revealed areas of the heart where the blood flow decreased because healthy heart tissue will absorb more tracer than delicate tissue and these tissues reduced blood flow. The different colours and degrees of brightness in the scan will indicate various levels of tissue function, which will help the patient and doctor to decide the best way forward.

3. Brain disorders:- Glucose is the primary oil of the brain. During PET scans, tracers “bind” with glucose. With the detection of radioactive glucose, the PET scan can detect which areas of the brain use glucose at the maximum rates. The doctor will examine the scan to see how the brain is functioning and to detect abnormalities. PET scan is used to help diagnose and control many central nervous system (CNS) disorders, which include:

• Depression
• Alzheimer disease
• Head trauma
• Parkinson’s disease
• epilepsy

Preparation of the patient

The optimal development for patients who are about to undertake PET / CT is evolving. The main objectives of the patient preparation are to minimise the uptake of the marker in normal tissues, like as the myocardium and skeletal muscle, while handling absorption in the target tissues. Commonly used protocols are:-

1. Pregnancy and lactation: See the Procedures Guide of the Society of Nuclear Medicine for general images.

2. Before arrival instruction:-Patients should be instructed to not consume any beverages, except water, for at least 4-6 h before the administration of 18F-FDG to reduce physiological levels of glucose and to decrease serum insulin levels to almost basal. Oral hydration with water recommend. The intravenous fluid contains parenteral feeding that retained for 4 to 6 h. When the intravenous contrast material is going to be used by the doctor before that patient should undergo a background check for allergy to iodinated contrast material. The metformin is applying for the treatment of diabetes mellitus, and kidney disease. Intravenous contrast material not be used, when the serum creatinine level is more than 2.0 mg / dL.

3. Before giving the injection to the patient:-

a. For brain imaging, the patient must be in a silence mode, low-light room for the administration of 18F-FDG and the subsequent uptake phase.
b. For body images, the patient must stay seated or reclined for the administration of 18F-FDG and the subsequent uptake phase to avoid muscle uptake.
c. The blood glucose level must check before of 18F-FDG. The tumour uptake of 18F-FDG is reducing in the states of hyperglycemia. Majority of institutions reschedule the patient to check the blood glucose level if it is greater than 150-200 mg / dL. Dropping the serum glucose level can be considered by the administration of insulin, but the administration of 18F-FDG should be a delay after insulin administration.

B. Relevant information to perform the procedure

1. History center, which includes the type and site of the malignancy, the dates of diagnosis and treatment (results of the biopsy, surgery, radiation, chemotherapy, and administration of stimulants of the bone marrow and steroids) and current medications.
2. Record of diabetes, fasting state and recent infectivity.
3. The patient’s ability to remain still during the acquisition (15-45 min)
4. History of claustrophobia.
5. The patient’s ability to put his arms on his head.

Recent advancement in various scan technologies, image interpretation criteria, and clinical management of patients with lymphoma place rising responsibility on radiologists to provide precise disease evaluation to deliver the best patient care. The diagnostic benefits of FDG PET/CT in initial staging and response evaluation is establishing. Residual FDG uptake on PET/CT scans obtained throughout and after first-line therapy is also associated with patient prognosis. To do this scan, various centers are available in the country, but pet ct scan in Bangalore is the first place where this scan was available. Now due to the rise in the cancer cases, almost every city pet ct scan is possible.

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