Is [18F]fluorodeoxyglucose Positron Emission Tomography the Ultimate Tool for Response and Prognosis Assessment?

The role of (18)F-fluorodeoxyglucose positron emission tomography in the diagnosis, staging, and follow-up of cholangiocarcinoma

(18)F-Fluorodeoxyglucose positron emission tomography ((18)FDG-PET) is a new diagnostic technique for the diagnosis and staging of cholangiocarcinoma. For diagnosis of a primary cholangiocarcinoma, (18)FDG-PET seems to be helpful to discriminate between malignant and benign lesions. However, the accuracy of (18)FDG-PET seems to be dependent on the anatomic location, growth pattern, and pathologic characteristics of the lesion. It has been proved that the accuracy of (18)FDG-PET is limited to detection of extrahepatic, infiltrating, and mucinous cholangiocarcinomas. Due to its lower sensitivity, (18)FDG-PET provides complementary rather than confirmative information in the diagnosis of regional lymph node metastasis. In contrast, it has high accuracy in detecting unsuspected distant metastases. The role of (18)FDG-PET in detecting cancer recurrence, monitoring treatment response, and predicting prognosis is still controversial.

PET scanning and prognosis in Hodgkin's lymphoma

PURPOSE OF REVIEW

Risk-adapted treatment strategies are currently under investigation in the management of patients with lymphoma. This review presents the latest evidence for the use of early interim [(18)F]-fluorodeoxyglucose-positron emission tomography for risk-adapted treatment in Hodgkin's lymphoma.

RECENT FINDINGS

In recent years, PET after two cycles of ABVD (adriamycin, bleomycin, vincristin, and dexamethasone) was shown to be the only independent prognostic factor for the prediction of relapse in Hodgkin's lymphoma and to have at least the same prognostic accuracy as end-of-treatment PET. A high prognostic value of PET was reported even earlier, before the second cycle of chemotherapy. The earlier PET becomes negative, the more chemosensitive the disease, which may offer opportunities toward the limitation of the therapy. However, more false-positive lesions occur at earlier time points, and preliminary results indicate that accuracy of PET results differs after BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone) and immunotherapy.

SUMMARY

[(18)F]-Fluorodeoxyglucose-positron emission tomography after two cycles of ABVD is now recognized as the single most important factor in defining disease-specific outcome and is highly promising for investigation of response-adapted treatment strategies. It is now recognized that the optimal time point of PET for response evaluation is crucial and dependent on the administered treatment. Standardization of PET-response is essential and should be adapted to time-dependent and therapy-dependent changes.

THE ACCURACY OF [18F]FLUORODEOXYGLUCOSE POSITRON EMISSION TOMOGRAPHY AS CONFIRMED BY BIOPSY IN THE DIAGNOSIS OF SPINE METASTASES IN A CANCER POPULATION

OBJECTIVE

To determine the accuracy of [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in the diagnosis of vertebral metastases in patients with cancer using needle-biopsy results and patient follow-up data.

METHODS

A retrospective chart review of all patients who underwent a needle biopsy of a spinal lesion and underwent FDG-PET within 6 weeks of the biopsy was performed. Biopsy results and magnetic resonance imaging and computed tomographic appearance of the biopsied lesion, as well as long-term clinical follow-up data, were recorded for each patient. A total of 82 patients with solid tumors and hematological spine metastases were included in this study.

RESULTS

The mean standardized uptake values of lesions with active cancer were 7.1 and 2.1 in benign lesions (P < 0.02). In patients with metastatic solid tumors, the mean standardized uptake value was 7.3. Stratification of solid tumor lesions according to whether they had a sclerotic appearance on computed tomographic scans showed that FDG-PET was a significantly better predictor of cancer status in lytic or mixed lesions. In patients with a history of solid tumors, there was 100% concordance between the FDG-PET and needle-biopsy diagnoses in nonsclerotic lesions, when the standardized uptake value cutoff of 2 was used.

CONCLUSION

FDG-PET is an accurate screening test for vertebral metastases in cancer patients. It is especially accurate in patients with nonsclerotic vertebral lesions and a history of solid malignancy.