Initial experience in staging primary oesophageal/gastro-oesophageal cancer with 18F-FDG PET/MRI

Background 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) may improve cancer staging by combining sensitive cancer detection with high-contrast resolution and detail. We compared the diagnostic performance of 18F-FDG PET/MRI to 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for staging oesophageal/gastro-oesophageal cancer. Following ethical approval and informed consent, participants with newly diagnosed primary oesophageal/gastro-oesophageal cancer were enrolled. Exclusions included prior/concurrent malignancy. Following 324 ± 28 MBq 18F-FDG administration and 60-min uptake, PET/CT was performed, immediately followed by integrated PET/MRI from skull base to mid-thigh. PET/CT was interpreted by two dual-accredited nuclear medicine physicians and PET/MRI by a dual-accredited nuclear medicine physician/radiologist and cancer radiologist in consensus. Per-participant staging was compared with the tumour board consensus staging using the McNemar test, with statistical significance at 5%. Results Out of 26 participants, 22 (20 males; mean ± SD age 68.8 ± 8.7 years) completed 18F-FDG PET/CT and PET/MRI. Compared to the tumour board, the primary tumour was staged concordantly in 55% (12/22) with PET/MRI and 36% (8/22) with PET/CT; the nodal stage was concordant in 45% (10/22) with PET/MRI and 50% (11/22) with PET/CT. There was no statistical difference in PET/CT and PET/MRI staging performance (p > 0.05, for T and N staging). The staging of distant metastases was concordant with the tumour board in 95% (21/22) with both PET/MRI and PET/CT. Of participants with distant metastatic disease, PET/MRI detected additional metastases in 30% (3/10). Conclusion In this preliminary study, compared to 18F-FDG PET/CT, 18F-FDG PET/MRI showed non-significant higher concordance with T-staging, but no difference with N or M-staging. Additional metastases detected by 18F-FDG PET/MRI may be of additive clinical value.

Analysis of factors affecting the accuracy of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in case of suspected prosthetic valve infective endocarditis

Aim. To analyze the factors affecting the accuracy of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (PET/CT) in case of suspected prosthetic valve endocarditis (PVE).Material and methods. The results of PET/CT performed in 66 patients after heart valve replacement were analyzed: 55 patients with suspected PVE (≥3 months after surgery) and 11 comparison groups without PVE (2 months after surgery). In the group with suspected PVE (n=55) at the time of the study, 27% (15/55) had a normal body temperature, 85% (47/55) — no leukocytosis. In 16% (9/55), the examination was performed from 3 to 6 months after surgery and in 67% (37/55) — against the background of long-term antibiotic therapy (ABT). The final diagnosis of PVE was made on the basis of clinical (including 6±3 followup), laboratory, instrumental, and intraoperative (n=40) data: confirmed — in 37 patients; ruled out — in 29 patients. In order to determine the influence of factors on obtaining false PET/CT results, the odds ratio was calculated.Results. In the group with suspected PVE (n=55), the PET/CT results made it possible to establish and rule out PVE in 92% (34/37) and 67% (12/18) of patients, respectively. In 16% (9/55) of patients, false positive (n=6) and false negative (n=3) results. Thus, the sensitivity, specificity and diagnostic accuracy of PET/CT in the diagnosis of PVE were 92%, 67% and 84%, respectively; positive and negative predictive values — 85% and 80%. The analysis of the odds ratio did not reveal the relationship of low inflammatory activity, the interval between surgery and PET/CT from 3 to 6 months, and long-term ABT before PET/CT with false PET/CT results (p>0,05). In the comparison group without PVE (n=11), 91% (10/11) received false positive PET/CT results, and one patient received a true negative result.Conclusion. The data obtained indicate the high informative value of PET/CT in the diagnosis of PVE. Interval >2 months between surgery and PET/CT significantly reduces the accuracy of PET/CT results. Other factors analyzed in the presented group did not affect the accuracy of PET/CT results.

The role of preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in retroperitoneal sarcoma

18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scan was used to predict pathologic grade based on the maximum standardized uptake value (SUVmax) in soft tissue sarcoma and bone sarcoma. In retroperitoneal sarcoma (RPS), the effectiveness of PET scan was not well known. This study is designed to investigate the association of SUVmax with histopathologic grade and usefulness of 18 F-FDG PET/CT scan preoperatively. Patients undergoing primary surgery for retroperitoneal sarcoma with preoperative 18F-FDG PET/CT imaging were investigated between January 2001 and February 2020 at Samsung Medical Center. The relationship between SUVmax and histologic features was assessed. The association of SUVmax with overall survival (OS), local recurrence (LR), and distant metastasis (DM) was studied. Of the total 129 patients, the most common histologic subtypes were liposarcoma (LPS, 68.2%) and leiomyosarcoma (LMS,15.5%). The median value of SUVmax was 4.5 (range, 1- 29). The value of SUVmax was correlated with higher tumor grade (p < 0.001, Spearman coefficient 0.627) and mitosis (p < 0.001, Spearman coefficient 0.564) and showed a higher value in LMS (12.04±6.73) than in dedifferentiated liposarcoma (DDLPS, 6.32±4.97, p = 0.0054). The optimal threshold to distinguish high tumor grade was 4.8. High SUVmax group based on the above threshold showed poor prognosis in OS, LR, and DM (p < 0.001). SUVmax was correlated with pathologic parameters (tumor grade, mitosis) in RPS and was higher in the LMS group than DDLPS group. In addition, prognosis (OS, LR, DM) was poor at high SUVmax values (p < 0.001). The value of SUVmax 4.8 is the optimal threshold to rule out high-grade tumors and predict prognosis.