Identifying and Distinguishing Treatment Effects and Complications from Malignancy at FDG PET/CT

Abstract

Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is increasingly used in the initial staging, evaluation of treatment response, and surveillance of many malignancies. Uptake of FDG is substantially increased in most malignancies, compared with its uptake in normal tissues, and the finding of FDG avidity often leads to cancer detection earlier than abnormalities can be seen at anatomic imaging. However, FDG is not a cancer-specific agent, and FDG avidity can be seen in many benign processes. It can be particularly challenging to discriminate malignancy from benign FDG-avid changes caused by surgery and procedures, radiation therapy, and chemotherapy. FDG-avid abnormalities caused by surgery and procedures include inflammation at sites of incision or dissection, inflammation from vascular compromise or surgical retraction, surgical transposition of structures with physiologic FDG avidity (such as ovaries or testes), and pleurodesis inflammation. Radiation therapy may induce FDG-avid pneumonitis, esophagitis, or hepatitis, as well as osteoradionecrosis or fractures. FDG-avid chemotherapy complications include pneumonitis, osteonecrosis, enterocolitis, and pancreatitis. Use of granulocyte colony stimulating factor for treatment of bone marrow suppression after chemotherapy induces temporary increases of FDG avidity in the bone marrow and spleen. Familiarity with common and unusual iatrogenic causes of FDG avidity that can confound interpretation of FDG PET/CT results will improve the accuracy of distinguishing treatment effects and complications from residual or recurrent malignancy at FDG PET/CT examinations.

Radiation-induced liver disease as a mimic of liver metastases at serial PET/CT during neoadjuvant chemoradiation of distal esophageal cancer

“…Perhaps the best known examples of pseudoprogression are increasing blastic change of bone lesions in breast and prostate cancer patients that might suggest worsening of metastases but may actually reflect healing by sclerosis [32–33]. Other examples include benign sequelae of chemoradiation and surgery that can result in FDG avidity, such as pneumonitis, esophagitis, and osteonecrosis [34]. Diffuse increase in FDG avidity in the bone marrow and spleen is commonly seen after treatment with granulocyte colony stimulating factor, which can also mimic metastases [35].…”

Fertility-sparing for young patients with gynecologic cancer: How MRI can guide patient selection prior to conservative management

“…Depending on the phase of ovulatory cycle, transposed ovaries may demonstrate physiologic fluorine 18-fluorodeoxyglucose (FDG) avidity on PET/CT (Figure 2). This should not be misinterpreted as metastatic disease (26). Metastases to transposed ovaries are extremely rare and have the same imaging features as metastases to non-transposed ovaries (23).…”

Ocena przydatności badań opóźnionych 18F-FDG PET/CT w różnicowaniu zmian łagodnych i złośliwych

“…Pomimo, że fluorodeoksyglukoza nie jest znacznikiem swoistym (ang. non tumor-specific) [4,[11][12][13], należy do najczęściej stosowanych radiofarmaceutyków w radioizotopowej diagnostyce onkologicznej.…”