Clinical PET/CT Oncology :Clinical PET/CT Oncology By: Jessenia Ramirez


Objectives :Objectives Describe intracellular F-18 FDG metabolism Determine the advantages and disadvantages Describe the ways in which PET oncology imaging can be performed Discuss what SPN is Describe the normal whole body FDG distribution


Intracellular F-18 FDG Metabolism :Intracellular F-18 FDG Metabolism F 18 FDG is a non physiological compound with a chemical structure similar to that of naturally occurring glucose. F-18 FDG serves as an external marker of cellular glucose metabolism It is the most widely used radiopharmaceutical in PET cancer imaging


Cont’d :Cont’d Malignant tumors have a greater affinity for glucose than normal cells which results in increased glucose flow into cancerous cells Hexokinase, 1st intracellular enzyme involved in glucose breakdown, is much more active in normal cells.


Advantages and Disadvantages :Advantages and Disadvantages FDG PET can serve as powerful screening tool in the investigation of a wide variety of cancers Cancers demonstrate an increase FDG utilization so it is an advantage in finding cancerous tumors Cancers are detected but so are other noncancerous conditions such as, infections, inflammation, muscular activity and healing tissues


Cont’d :Cont’d Since these all show up as increased FDG utilization, a simple infection can come up as a cancerous tumor Thus FDG PET cancer screening is a broad- base approach


Patient Prep and Injection :Patient Prep and Injection FDG are extremely sensitive to small changes in tissue metabolism, therefore it is critical to ensure the patients baseline metabolic activity starts at low levels and the patient remains at rest prior to, during and after injection After the IV line is started the patient must be placed in a bed or chair for 10 mins and must refrain from talking


Cont’d :Cont’d If the patients has barriers such as language, hearing or learning it must be addressed before patients arrival Patients must fast for 4-6 hrs before appointment to reduce peripheral blood glucose, if not the blood glucose competes with FDG and there will be little difference between tumors and normal soft tissue uptake The ideal value of blood glucose should be less than 120mg/dl


Administration of FDG :Administration of FDG FDG should be administered while the patient is in a resting state. 10-20 mCi is administered The injection is performed using a 3way stopcock attached to the IV line and to the dose syringe. After injection the IV should be flushed with 20-30 mL of saline Patient should void immediately prior to imaging


PET Scan Acquisition :PET Scan Acquisition PET oncology imaging can be performed in several ways: Limited area scanning: is used when the patients history indicates the need to evaluate only a very specific area of the body. Dynamic imaging: requires continuous imaging in a single bed position


Cont’d :Cont’d Imaging from base of skull to mid-thigh: most common in oncology studies. Requires 5-8 bed positions and are obtained just after patient has voided. Total body imaging: performed if there is a question that a cancer might include the head or legs. Requires more then 10 bed positions and covers from the top of head through the feet. Most commonly used for patients with malignant melanomas


Normal Whole Body FDG Distribution :Normal Whole Body FDG Distribution The most common and constant sites of intense activity are: Brain Liver Kidneys Bladder


Normal Variations in FDG Localization :Normal Variations in FDG Localization Myocardial activity is the most noticeable normal variation in FDG localization There are two sets of normal variations that occasionally cause misdiagnoses: GI tract activity Muscular or brown fat activity in the neck and shoulders


Cont’d :Cont’d Exercise, shivering, and even muscular tension can lead to increased FDG This then appears as if there was a metastatic disease but its due to the increased FDG uptake in that area


Solitary Pulmonary Nodule :Solitary Pulmonary Nodule SPN were the 1st FDG PET oncology studies covered by Medicare Increased FDG utilization in a SPN suggests malignancy PET outperforms CT in determining whether an SPN is malignant or non malignant


Mesothelioma :Mesothelioma A rare form of cancer that develops in the lining of the chest It may also occur in the peritoneum or the pericardium as well Most people that have mesothelioma have had some exposure to asbestos during there lifetime


Melanoma :Melanoma Skin tumors characterized by the malignant growth of melanocytes PET is the best screening examination for high risk melanoma patients Any patient with a history of melanoma should have a total body scan


Lymphoma :Lymphoma A tumor arising from the lymph nodes Two types of lymphomas are Hodgkin’s (HD) and non Hodgkin’s disease (NHD) Factors to consider with a pt with Hodgkin’s disease: number and location of diseased lymph nodes, presence of disease on one or both sides of diaphragm, and metastatic spread to bone marrow, liver, lung, spleen or bones


Myeloma :Myeloma A disease that begins in the marrow of the bone Occurs when plasma cells form a mass in the marrow If patients are asymptomatic, the best decision may be to forego the treatment due to the risks and side effects outweighing the benefits The main form of treatment for myeloma is chemotherapy


Colorectal Cancer :Colorectal Cancer This cancer is more prominent in individuals older than 50 who have a personal or family history of this disease Frequently metastasizes to the liver FDG PET can be used to search for cancer when the patients plasma tumor markers are rising and conventional anatomic imaging techniques have failed to detect any disease


Head and Neck Cancer :Head and Neck Cancer PET is an excellent imaging choice for this cancer Head and neck carcinoma may spread to the lungs FDG PET accurately identifies tumor recurrences


Esophageal Cancer :Esophageal Cancer Esophageal cancer continues to be diagnosed in advanced stages, leading to very little survival The origin of this cancer is still not understood PET shows levels of hypermetabolism at the cellular level using FDG


Breast Cancer :Breast Cancer Expect for skin cancer, breast cancer is the #1 malignant tumor in women Because of FDG utilization being related to cellular metabolism, PET can help demonstrate responses to therapy FDG PET may offer a method of determining which of the therapy options has greater success


Brain Cancer :Brain Cancer Brain tumors are classified by grade, low grade (I) to high grade (IV) Gliomas are the most common brain tumors Because the normal cerebral and cerebellar neurons utilize FDG, brain tumors can be and are missed FDG PET is used to help differentiate residual tumors from radiation necrosis and edema and not as a screening tool for metastatic brain tumors


Prostate Cancer :Prostate Cancer Occurs in males over the age of 50 Tends to grow more slowly than other cancers FDG PET does not detect the presence of local disease very well An abnormal FDG PET scan in pts with prostate cancer almost always indicates the presence of local metastatic disease


Cervical Cancer :Cervical Cancer Estimated that 3700 women will die of this disease annually HPV is one of the major risk factors associated with this cancer PET can be an important diagnostic tool in the initial staging of pts with cervical carcinoma


Ovarian Cancer :Ovarian Cancer Fairly common and deadly cancer in women The most prominent sign is enlargement of the abdomen If considered a high risk for ovarian carcinoma they should have a combination of a pelvic exam, transvaginal u/s, and blood test for the tumor marker PET/CT imaging in the pelvis may require bladder catheterization


Testicular Cancer :Testicular Cancer Divided into major categories: seminomas and non seminomas germ cell tumors Most common solid tumors in young males Treated with a combination of surgery, radiation and chemotherapy Seminomas utilize FDG FDG maybe beneficial in the staging and restaging of these tumors


Cont’d :Cont’d This tumors show very little FDG activity and cannot be distinguished from necrotic or fibrous tissues


Thyroid Cancer :Thyroid Cancer Divided into two main categories: Follicular cell tumors: makes thyroid hormones C-cell tumors: forms calcitonin FDG presents inherent diagnostic problems, these two points must be emphasized: FDG PET imaging is a reasonable approach to search for more poorly differentiated forms of thyroid cancer


Cont’d :Cont’d When unexplained abnormal findings occur in the thyroid on FDG PET examinations obtained for other indications, additional conventional tests should be performed to exclude unsuspected thyroid cancers


Pancreatic Cancer :Pancreatic Cancer Almost 32,000 people will die of pancreatic cancer annually It typically begins in the pancreatic ducts and about 60%-70% of all tumors are found in the head of the pancreas PET has shown to be helpful in differentiating chronic pancreatic masses from malignant disease


Question 1 :Question 1 Define F-18 FDG


Answer 1 :Answer 1 F 18 FDG is a non physiological compound with a chemical structure similar to that of naturally occurring glucose


Question 2 :Question 2 What is Hexokinase?


Answer 2 :Answer 2 1st intracellular enzyme involved in glucose breakdown


Question 3 :Question 3 What is a disadvantage of F18 FDG?


Answer 3 :Answer 3 a simple infection can come up as a cancerous tumor


Question 4 :Question 4 What is the idea blood glucose?


Answer 4 :Answer 4 The ideal value of blood glucose should be less than 120mg/dl


Question 5 :Question 5 What is mesothelioma?


Answer 5 :Answer 5 A rare form of cancer that develops in the lining of the chest


Question 6 :Question 6 Name the two normal variations that occasionally cause misdiagnoses


Answer 6 :Answer 6 GI tract activity Muscular or brown fat activity in the neck and shoulders


Question 7 :Question 7 Testicular scan is divided into two major categories. What are they? seminomas and non seminomas germ cell tumors


Answer 7 :Answer 7 Seminomas and non seminomas germ cell tumors


Question 8 :Question 8 What are the most common brain tumors?


Answer 8 :Answer 8 Gliomas


Question 9 :Question 9 What does PET differentiate in pancreatic cancer?


Answer 9 :Answer 9 chronic pancreatic masses from malignant disease


Question 10 :Question 10 What is testicular cancer treated with?


Answer 10 :Answer 10 Treated with a combination of surgery, radiation and chemotherapy