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PET/CT Symposium: Q&A

March 20, 2018

Want to know more about the value and advancements of PET/CT at Cardinal Santos Medical Center (CSMC)? Read on to learn from CSMC's medical experts and Dr. Gustav von Schulthess as they tackle on the remaining list of questions submitted by participants during the PET/Ct Symposium's Open Forum held on March 20, 2018 at the Events Center, PCAS Building, Cardinal Santos Medical Center.

Q: Does your center do additional 30min head and neck protocol imaging aside from whole body scan for head and neck ca?

A: No

Q: Which tracers are available here in CSMC?

A: F-18 FDG and F-18 choline

Q: How sensitive is PET/CT SCAN in detecting pancreatic carcinoma? Interested to hear you experience with this PET CT Sensitivity, specificity and accuracy in detecting pancreatic cancer

A: Sensitivity: 85%-97%

Accuracy: 85%-95%.

Specificity is relatively low at 61%-94%

Source: Xiao-Yi Wang, Feng Yang, Chen Jin, De-Liang Fu. Utility of PET/CT in diagnosis, staging, assessment of resectability and metabolic response of pancreatic cancer. World J Gastroenterol 2014 November 14; 20(42): 15580-15589


1. Tang et al:

Pooled sensitivity of 90.1%

specificity of 80.1%

Source: Tang S, et al. Usefulness of 18F-FDG PET, combined FDG-PET/CT and EUS in diagnosing primary pancreatic carcinoma: a meta-analysis. Eur J Radiol 2011; 78: 142-150

2. Wu et al

Pooled sensitivity of 87%

specificity of 83%.

Source: Wu LM, et al. Diagnostic value of diffusion-weighted magnetic resonance imaging compared with fluorodeoxyglucose positron emission tomography/computed tomography for pancreatic malignancy: a meta-analysis using a hierarchical regression model.J Gastroenterol Hepatol 2012; 27: 1027-1035

Q: Do you recommend diet modification as complement to therapy

A: A healthy, well-balanced diet rich in fiber, complex carbohydrates, protein, good fats, vitamins and minerals is encouraged, on and off therapy.

Q: For people who are prone to certain cancers (genetics) who want to go through PET/CT scan as part of their regular check-up. Is this ok?

A: PETCT is best utilized in evaluating the extent of the disease (such as nodal and distant metastasis) in a patient with a KNOWN cancer. It is a valuable tool for therapy monitoring and to detect recurrence. For individuals AT RISK for malignancy, it is advised that we follow the guideline for early detection pertaining to the specific cancer. For instance, a routine mammography and breast sonography for those at risk for breast cancer, or an early colonoscopy for colon cancer.

Q: TB is common in the Philippines, it also has uptake on PET, can we differentiate TB from CA?

A: It is technically difficult to differentiate Tuberculosis from carcinoma because CT features between the two entities overlap and both may have significantly increased SUVmax

Q: Can SUV quantify/at least qualify response of tumors to certain chemotherapy agents? (E.g. osteosarcoma)

A: Yes, generally, a decrease in SUVmax in a tumor following a course of chemotherapy suggests disease regression.

Q: Are there anymore radiation moeity useful for PET/CT aside from Fluorine-18?

A: Yes. We have C-11 acetate for liver study, pittsburg compound to detect plaques in Alzeimer’s disease, N-13 ammonia and O-15 water for cardiac PET perfusion study, Ga-68 Dotatate for neuroendocrine tumors, Ga-68 PSMA for prostate cancer, to name a few.

Q: How can we influence better take-up of PET/CT scan (patients & oncologists) in the Philippines?

A: Increase awareness that PET CT is an indispensible tool in knowing the extent of the disease that can subsequently change the treatment and management plan. It is likewise an important aspect in therapy monitoring and to detect disease recurrence. Government subsidy for PET CT will help in alleviating the financial burden of cancer imaging and treatment in general.

Q: What cardiac pathology would best benefit from PET CT?

A: Ischemic heart disease and coronary artery disease

Q: Pet ct can identify abscess vs neoplastic process?

A: Most of the time yes, based on history and radiologic morphology.

Q: Example: lung CA with brain metastasis, using PET CT Scan, do we need to use two kinds of tracers? Or can we use MRI for the brain Instead?

A: We can use PET CT to detect, evaluate and monitor brain PET. FDG will suffice for a metastatic lesion. However, for a brain lesion that has undergone treatment (eg. Gamma knife surgery, radiation treatment to the brain), F-18 ethyl tyrosine is a good tracer to use to differentiate between inflammation/ post treatment changes versus recurrence/ residual disease.

Q: For a patient with pulmonary mass but also has pneumonia, will the presence of pneumonia affect the result of a suspected malignancy?

A: No, unless pneumonia masks the pulmonary lesion or mass.

Q: What significant differences are there between pet/ct and pet/mr clinically?

A: PET/MR is best used to evaluate the head and neck region and the pelvic region. It is a good tool for gynecologic malignancy and cancers arising from the head and neck area.

Q: What is the status of pet mammography?

A: According to Dr. Gustav, it is still best to assess the breast mass/ lesion with a digital mammography and/ or breast ultrasound.

Q: Do you recommend PETCT to be used as a substitute for biopsy in primary diagnosis of CA?

A: No. PET CT cannot substitute a biopsy as tissue sampling is the gold standard in diagnosing cancer. However, a PET CT can guide the surgeon or the interventional radiologist on the best lesion to biopsy

Q: Do the PET tracers produced i your centers undergo registration and regulation processes?

A: Yes. It undergoes strict regulatory process and quality control from the FDA

Q: From RT-Intern30, does the short half-life of the tracer used has an advantage to PET Imaging versus longer-lived tracers?

A: It has the advantage of having less radiation burden

Q: From RT-Intern 30, Are there anymore Radiation Moeity available for PET/CT aside from Fluorine-18 and Gallium-68?

A: Answered above

Q: From RT-Intern30-How will PET-CT be in the future?

A: FDG PET CT is the workhorse in cancer imaging. Through the years, it is proven to be a useful and effective tool in disease staging, monitoring treatment response and detecting recurrence. Currently, PET CT is included in several guidelines (eg. NCCN, AJCC) in the monitoring and management of cancer; and will likely be in the foreseeable future.