[Impact of (18)F-FDG PET/CT on the therapeutic management in the initial staging of the esophageal cancer]

OBJECTIVE

The incidence of esophageal cancer has increased considerably over recent years, it now being the 6th most frequent cause of cancer-related death. Our study has aimed to compare the clinical value of PET/CT and CT scan in the initial staging of patients with esophageal cancer.

MATERIAL AND METHODS

Fifty nine patients (6 women) diagnosed of esophageal cancer were assessed retrospectively. All patients underwent diagnostic CT scan and PET/CT for initial staging within 3 to 15 days following clinical diagnosis.

RESULTS

PET/CT showed intracellular (18)F-FDG entrapment having pathological significance in all the tumors (100%), signs of locoregional lymph node infiltration (N1) in 34 and a total of 19 lesions consistent with metastasis (M1) in 14 patients (23.72%). The CT scan detected malignancy in 57 patients (96.6%), abnormal lymph node in 32 patients and 17 N1 in 12 patients (20.33%). In three cases, CT- PET detected synchronous esophageal lesion in staging studies for other neoplastic processes (lung and ear-nose-throat).

CONCLUSION

PET/CT showed a higher detection rate of primary malignant lesions, abnormal lymph nodes and distant metastases. A change in stage was only observed in two patients.

[Positron emission tomography using 18-FDG-PET in radiologically indeterminate pulmonary lesions]

OBJECTIVE

Fluorine-18 deoxyglucose Positron Emission Tomography (FDG-PET) is a non-invasive technique that offers the possibility to define if the radiologically indetermined pulmonary lesions are benign or malignant with high positive and negative predictive values. Considering the indexed literature we can observe that there are few original studies performed with the diagnostic possibilities of our means. For this reason, our main objective is to evaluate the diagnostic accuracy of positron emission tomography in sixty-seven radiologically indetermined pulmonary nodular lesions.

MATERIAL AND METHOD

Retrospectively, we evaluated the diagnostic ability of FDG-PET globally (by means of visual and semiquantitative analysis) and partially (only considering the Standardized Uptake Value (SUV)), in sixty-seven patients confirmed by pathology or clinical and radiological monitoring, in a time interval superior to one year.

RESULTS

Globally, FDG-PET had a sensitivity (S) of 92%, specificity (SP) of 86.6%, positive predictive value (PPV) of 89.4%, negative predictive value (NPV) of 89.6% and diagnostic accuracy (DA) of 89%. The best results were obtained for an SUV equal or superior to 2.5. With this value, the clinical efficacy parameters were: S 0.92, SP 0.90, PPV 0.92, NPV 0.90 and DA 0.91.

CONCLUSIONS

We can characterize most of the radiologically indetermined pulmonary lesions by FDG-PET. The additional use of SUV facilitates an increase in the positive predictive value and specificity of FDG-PET.

[Diagnostic accuracy of semiquantitative analysis of positron emission tomography in radiologically indeterminate lung lesions]

OBJECTIVE

The objective of this work was to assess the Standardized Uptake Value (SUV) in the differential diagnosis of radiologically indeterminate lung lesions by means of ROC curves.

MATERIAL AND METHOD

Forty seven patients were studied by Positron Emission Tomography with 18-fluorine-2-desoxy-D-glucose (FDG PET) analyzing the value of maximum SUV. The patients were classified into three groups. Group 1 = patients without previous neoplasia (WPN) + patients with previous neoplasia (PN). Group 2 = WPN. Group 3 = PN.

RESULTS

The ROC curves showed a high diagnostic accuracy in the three groups, with area under the curve (AUC) values of 0.96, 0.98 and 0.91 respectively. The typical error was 0.03, 0.02 and 0.08. The maximum SUV cutoffs with the best diagnostic accuracy for the three groups were: 2.6; 3 and 2.4, with an accuracy (A) of 93.6%, 97% and 92.3%, respectively. Analyzing all the patients globally (group 1), we obtained one false positive result in a patient with hamartoma (max SUV = 2.8) and two false negative results in one patient with lung metastases from malignant fibrohistiocytoma (max SUV = 0.7) and in another patient with lung metastases from unknown origin adenocarcinoma (max SUV = 1.9).

CONCLUSIONS

FDG PET permits differentiation with a very high diagnostic accuracy of benign and malignant lung lesions using the maximum SUV. The differences observed between the different groups are due to the different disease prevalence, obtaining a lower negative predictive value of max SUV in patients with previous neoplasia.