Detection of Primary Malignancy and Metastases with FDG PET/CT in Patients with Cholangiocarcinomas: Lesion-based Comparison with Contrast Enhanced CT

Role of 68 Ga-FAPI PET/CT in Assessing Hepatobiliary Malignancies : A Prospective Pilot Study

INTRODUCTION AND AIM

Preliminary studies showed good expression of fibroblast activating protein inhibitor (FAPI) in hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). Our aims were to study the diagnostic performance of 68 Ga-FAPI PET/CT in diagnosing the primary hepatobiliary malignancies and to compare its performance with 18 F-FDG PET/CT.

PATIENTS AND METHODS

Patients suspected to have HCC and CC were recruited prospectively. FDG and FAPI PET/CT studies were completed within 1 week. Final diagnosis of malignancy was achieved by tissue diagnosis (either histopathological examination or fine-needle aspiration cytology) and radiological correlation from conventional modalities. Results were compared with final diagnosis and expressed as sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy.

RESULTS

Forty-one patients were included. Thirty-one were positive for malignancy and 10 were negative. Fifteen were metastatic. Of 31, 18 were CC and 6 were HCC. For overall diagnosis of the primary disease, FAPI PET/CT performed exceptionally compared with FDG PET/CT with sensitivity, specificity, and accuracy of 96.77%, 90%, and 95.12%, respectively, versus 51.61%, 100%, and 63.41% for FDG PET/CT. FAPI PET/CT clearly outperformed FDG PET/CT for the evaluation of CC with sensitivity, specificity, and accuracy of 94.4%, 100%, and 95.24%, respectively, whereas for FDG PET/CT sensitivity, specificity, and accuracy were 50%, 100%, and 57.14%, respectively. Diagnostic accuracy of FAPI PET/CT was 61.54% for metastatic HCC compared with 84.62% for FDG PET/CT.

CONCLUSIONS

Our study highlights the potential role of FAPI-PET/CT in evaluating CC. It also ascertains its usefulness in the cases of mucinous adenocarcinoma. Although it showed a higher lesion detection rate than FDG in primary HCC, its diagnostic performance in the metastatic setting is questionable.

Impact of 18F-FDG-PET/CT on Clinical Management in Patients with Cholangiocellular Carcinoma

Objective:

To determine the impact of ¹⁸F-FDG-PET/CT on clinical management of patients with cholangiocellular carcinoma (CCA).

Methods:

Patients with CCA undergoing clinically indicated ¹⁸F-FDG-PET/CT between 04/2013 and 08/2018 were prospectively included in a local PET/CT registry study. Intended clinical management (“non-treatment” such as watchful-waiting or additional diagnostic tests, and “palliative” or “curative treatment”) was recorded before and after PET/CT. Changes in intended management after PET/CT were analyzed.

Results:

27 patients (mean age: 60 years, IQR: 51.5–67.5 years, 56% males) with 43 PET/CT examinations were included. Intended management changed in 35/43 cases (81.4%) following PET/CT. Major changes (i.e., between “non-treatment” and “treatment” strategies or between a “curative” and “palliative” treatment goal) occurred in 27/43 (62.8%) cases. Before PET/CT, additional imaging and/or biopsy were intended in 21/43 (48.8%) and 9/43 (20.9%) cases, respectively. After PET/CT, further imaging was carried out in one case and imaging-targeted biopsy in eight cases. Although the absolute number of biopsies after PET/CT did not decrease, in only one of these eight cases biopsy had already been planned before PET/CT, whereas in the other eight cases, the originally planned biopsies were dispensable after PET/CT.

Conclusions:

¹⁸F-FDG-PET/CT significantly impacts clinical management of patients with CCA. It guides decisions on treatment strategy (especially curative vs palliative treatment goal) and on additional tests, particularly by helping referring clinicians to avoid unnecessary imaging and by guiding targeted biopsy.

Advances in knowledge:

Systematic implementation of ¹⁸F-FDG-PET/CT may enable a more appropriate and tailored treatment of patients with CCA, especially in cases of suspected recurrence.

Clinical significance of preoperative CA19-9 and lymph node metastasis in intrahepatic cholangiocarcinoma

PURPOSE

This study aimed to identify prognostic factors for patients with ICC after a curative resection and clarify the appropriate indications for surgical resection and postoperative adjuvant chemotherapy.

METHODS

This retrospective study included 81 patients who underwent curative resection for ICC between April 1995 and December 2014. Kaplan-Meier and Cox regression models were used to analyze the effects of clinicopathological features on overall and recurrence-free survival.

RESULTS

The cumulative 5-year overall survival of 81 patients was 57.2%, and the 5-year recurrence-free survival was 24.0%. The multivariate analysis identified the lymph node status and preoperative CA19-9 levels as independent prognostic factors for overall survival. The 5-year overall survival rates were 79.9% and 38.7% in patients with normal and elevated CA19-9, respectively (p < 0.0001). The 5-year overall survival rates of patients with and without nodal metastasis were 33.7% and 60.9%, respectively (p = 0.0007). After adjusting for prognostic factors identified in a Cox regression analysis, we found that nodal-positive disease was significantly associated with benefit from adjuvant chemotherapy (HR 0.32, p = 0.03).

CONCLUSIONS

Surgical resection with curative intent combined with regional lymph node dissection should be indicated for ICC patients with normal CA19-9 levels. Postoperative adjuvant chemotherapy should be administered to high-risk patients with a positive nodal status.