18F-FDOPA PET/CT for detection of recurrence in patients with glioma: prospective comparison with 18F-FDG PET/CT.

PURPOSE: Differentiation between recurrence and radiation necrosis in patients with glioma is crucial, since the two entities have completely different management and prognosis. The purpose of the present study was to compare the efficacies of (18)F-FDG PET/CT and 3,4-dihydroxy-6-[(18)F]fluoro-phenylalanine ((18)F-FDOPA) PET/CT in detection of recurrent gliomas. METHODS: A total of 28 patients (age 38.82 ± 1.25 years; 85.7% men) with histopathologically proven glioma with clinical/imaging suspicion of recurrence were evaluated using (18)F-FDG PET/CT and (18)F-FDOPA PET/CT. (18)F-FDG PET/CT and (18)F-FDOPA PET/CT images were evaluated qualitatively and semiquantitatively. The combination of clinical follow-up, repeat imaging and/or biopsy (when available) was taken as the reference standard. RESULTS: Based on the reference standard, 21 patients were positive and 7 were negative for tumour recurrence. The sensitivity, specificity and accuracy of (18)F-FDG PET/CT were 47.6%, 100% and 60.7%, respectively, and those of (18)F-FDOPA PET/CT were 100%, 85.7% and 96.4%, respectively. The results of (18)F-FDG PET/CT and (18)F-FDOPA PET/CT were concordant in 57.1% of patients (16 of 28) and discordant in 42.9% (12 of 28). The difference in the findings between (18)F-FDG PET/CT and (18)F-FDOPA PET/CT was significant (P = 0.0005, McNemar's test). The difference was significant for low-grade tumours (P = 0.0039) but not for high-grade tumours (P = 0.250). CONCLUSION: (18)F-FDOPA PET/CT is highly sensitive and specific for detection of recurrence in glioma patients. It is superior to (18)F-FDG PET/CT for this purpose and is especially advantageous in patients with low-grade gliomas.

Comparative diagnostic accuracy of contrast-enhanced MRI and (18)F-FDOPA PET-CT in recurrent glioma.

OBJECTIVES: To compare the diagnostic accuracy of contrast enhanced magnetic resonance imaging (Ce-MRI) and (18)F-fluorodopa ((18)F-FDOPA) positron emission tomography (PET)-computed tomography (CT) for detecting recurrent glioma. METHODS: In this prospective study, 35 patients (age, 36.62 ± 0.86 years; 80 % male) with histopathologically proven glioma with clinical suspicion of recurrence were evaluated using Ce-MRI and (18)F-FDOPA PET-CT. (18)F-FDOPA PET-CT images were evaluated qualitatively and semi-quantitatively. Combination of clinical follow-up (minimum 1 year), repeat imaging and/or biopsy (when available) was taken as the reference standard. RESULTS: Based on the reference standard, 26 patients were positive and nine were negative for recurrence. The sensitivity, specificity and accuracy of Ce-MRI were 92.3 %, 44.4 % and 80 % respectively, whereas those of (18)F-FDOPA PET-CT were 100 %, 88.89 % and 97.1 % respectively. Results of Ce-MRI and (18)F-FDOPA PET-CT were concordant in 74.3 % (29/35) and discordant in 17.1 % of patients (6/35). On McNemar analysis the difference was not statistically significant overall (P = 0.687), for high-grade tumour (P = 0.5) or low-grade tumours (P = 1.0). However, (18)F-FDOPA PET-CT was more specific than Ce-MRI overall (P = 0.0002), for high-grade tumour (P = 0.006) and low-grade tumours (P = 0.004). CONCLUSION: F-FDOPA PET-CT shows a high but comparable diagnostic accuracy to Ce-MRI for the detection of recurrent glioma. However, it is more specific than Ce-MRI. KEY POINTS: • Recurrent glioma in the postoperative site remains a diagnostic dilemma. • (18) F-FDOPA PET-CT shows high diagnostic accuracy for detecting recurrent glioma. • Diagnostic accuracies for (18) F-FDOPA PET-CT and contrast enhanced MRI are comparable. • However, (18) F-FDOPA PET-CT is more specific than Ce-MRI for recurrent glioma.

Detection and localization of post-operative and post-traumatic bile leak: hybrid SPECT-CT with 99mTc-Mebrofenin.

PURPOSE: To evaluate the role of single photon emission tomography-computed tomography (SPECT-CT) with 99mTc-N-(3-bromo-2,4,6-trimethylacetanilide) iminodiacetic acid (Mebrofenin) for detection and localisation of post-operative and post-traumatic bile leak and compare the same with planar hepatobiliary scintigraphy (HBS). METHODS: Data of 32 consecutive patients (Age--35.7 ± !15.3 years; Female--53.2%) who underwent 99mTc-Mebrofenin planar HBS and SPECT-CT for suspected bile leak was prospectively collected and retrospectively analyzed. Twenty-six patients were post-operative and six had history of abdominal trauma. Planar HBS and SPECTCT images were evaluated by two experienced nuclear medicine physicians. Sensitivity, specificity and predictive values, were calculated for planar HBS and SPECT-CT. Final diagnosis was established based on a combination of re-operative findings, follow up imaging and clinical follow up (1-4 week).For evaluation of observer confidence a third observer used a scoring scale of 1-5, with 1 being definite bile leak and 5 being no leak. Receiver operating characteristic (ROC) curves were drawn and the areas under the curves were compared. RESULTS: The sensitivity, specificity and accuracy of SPECT-CT were 88.8%, 100% and 96.8% while that of planar HBS were 77.7%, 60.8% and 65.6%, respectively. Planar HBS showed very low diagnostic accuracy compared to SPECT-CT (65.6%vs. 96.8%; P = 0.021). It was false positive in nine patients. SPECT-CT also correctly localised the site of bile leak in eight of nine patients. On ROC analysis the observer confidence for SPECT-CT was significantly better than that for planar scintigraphy (P = 0.045). CONCLUSION: 99mTc-Mebrofenin hybrid SPECT-CT is highly sensitive and specific for detection and localisation of post-operative and post-traumatic bile leak. It is more accurate than planar HBS and should be routinely done in such patients.

Prospective comparison of (99m)Tc-GH SPECT/CT and (18)F-FDOPA PET/CT for detection of recurrent glioma: a pilot study.

OBJECTIVE: This study aimed to evaluate and compare the role of Tc-GH SPECT/CT and F-FDOPA PET/CT for diagnosing recurrence in patients with glioma. METHODS: Thirty patients with histopathologically proven glioma (glioblastoma multiforme, 14; grade III, 6; grade II, 8; and grade I, 2), who presented with clinical and/or imaging suspicion of recurrence were prospectively evaluated. They were primarily treated with surgery and radiotherapy with or without chemotherapy. Each patient underwent Tc-GH SPECT/CT and F-FDOPA PET/CT within a span of 15 days. Images were evaluated qualitatively and quantitatively by 2 experienced nuclear medicine physicians in consensus. Histopathology and/or clinical/imaging follow-up were used as reference standard. RESULTS: Based on reference standard, 22 patients were positive and 8 were negative for recurrence. Tc-GH SPECT/CT was positive for recurrence in 22 and negative in 8 patients. F-FDOPA PET/CT scan was positive for recurrence in 23 and negative in 7 patients. Sensitivity, specificity, and accuracy were 86.4%, 62.5%, and 80% for Tc-GH SPECT/CT and 100%, 87.5%, and 96% for F-FDOPA PET/CT, respectively. No significant difference was found between Tc-GH SPECT/CT and F-FDOPA PET/CT overall (P = 1.00), as well as for low-grade (P = 0.250) or high-grade tumors (P = 0.50). Significant correlation was noted between tumor-brain of Tc-GH with both tumor-striatum (r = 0.371; P = 0.044) and tumor-cerebellum ratio of F-FDOPA (r = 0.369; P = 0.045). CONCLUSIONS: For detection of recurrence in glioma patients, Tc-GH SPECT/CT is not inferior to F-FDOPA PET/CT and can be used as a low-cost alternative.