Imaging techniques play an important role in the diagnosis, staging, efficacy evaluation, and prognosis of hepatocellular carcinoma.
What is PET-CT?
PET-CT, known as positron emission computed tomography (PET-CT), is an advanced imaging tool that integrates function and anatomy to show abnormal functional metabolism in the body by injecting minute amounts of radioactive imaging agent into the body. The CT is used to determine the functional and anatomical changes of the lesion.
Unique value of PET-CT in the diagnosis and treatment of liver cancer
18F-FDG (fluorine-18-deoxyglucose) is the most commonly used radiographic agent in clinical practice, so what is the unique clinical value of 18F-FDG PET-CT in the diagnosis and treatment of liver cancer?
Diagnosis
PET-CT is less sensitive for the diagnosis of hepatocellular carcinoma, especially in moderately to highly differentiated grades.
However, in patients with hepatocellular carcinoma who are followed up after treatment, if conventional imaging such as CT and MRI does not reveal abnormalities, but alpha fetal protein (AFP) is progressively or persistently elevated, and there is clinical suspicion of residual tumor, recurrence, or metastasis, whole-body PET-CT may look for some extrahepatic recurrent metastases or The tumor residual foci may be detected by whole-body PET-CT.
Staging and restaging
Staging and restaging
The greatest advantage of PET-CT examination is that a single image of the patient’s entire body (routinely from head to mid-thigh) provides a comprehensive visual assessment of the patient’s entire body (lymph node metastases and metastases to distant organs), allowing clinicians to accurately stage the patient and thus select the appropriate treatment plan.
PET-CT, with the advantage of functional imaging, allows early detection of lesions with abnormal uptake of glucose metabolism without significant morphologic changes, such as morphologically normal-sized lymph nodes.
Because PET functional imaging is anatomically independent, it can accurately show recurrent metastases after anatomic changes or in areas with complex anatomy, allowing PET-CT to accurately restage patients after surgery or combination therapy for liver cancer.
Efficacy evaluation
PET-CT as an efficacy assessment tool allows early assessment of the efficacy of liver cancer treatment in terms of changes in focal glucose metabolism. In particular, targeted drugs aimed at inhibiting hepatocellular carcinoma activity will be more sensitive and accurate than conventional imaging methods to assess efficacy based on changes in tumor size.
In addition, a single imaging session can comprehensively evaluate systemic lesion glucose metabolism as well as morphologic changes so that clinicians can adjust treatment plans in a timely manner, allowing patients to avoid unnecessary pain and prolong their survival.
Guiding the outlining of biological targets for radiotherapy, puncture biopsy sites
PET-CT exams can provide both functional and anatomical information about liver cancer lesions, guiding the overall extent of the radiotherapy biotarget and the calculation of target volume.
Because some hepatocellular carcinoma lesions are prone to internal necrosis, puncture based on PET-CT showing high glycolytic uptake of the lesion will avoid necrotic areas and improve the positivity and accuracy of puncture.
Evaluation of the malignancy and prognosis of the lesion
The SUVmax value is commonly used clinically as a measure of focal glucose uptake. 18F-FDG is a glucose analogue, and in general, a higher focal glucose uptake, i.e., a higher SUVmax value, indicates a high metabolism of tumor cells, a higher malignancy of liver cancer, and a worse prognosis for the patient. Thus, the prognosis of the patient can be initially assessed based on the level of 18F-FDG uptake.
Preoperative screening and postoperative evaluation of liver transplantation
18F-FDG PET-CT “one-stop” whole-body imaging can better screen for patients who will benefit from liver transplantation, improve survival of transplant patients, and predict patient prognosis based on tumor stage and glucose metabolism uptake.
For post-transplant evaluation, PET-CT exams can detect tumor recurrence and metastasis early after liver transplantation for liver cancer.