MATERIALS AND METHODS: The clinical data and scintigraphy findings of patients referred to the Department of Nuclear Medicine, Hospital Kuala Lumpur for Tc-99m TRODAT-1 SPECT-CT from July 2022 to July 2023 were retrospectively reviewed. Follow-up with primary team was conducted to determine the clinical implications and subsequent therapeutic management of the patients.
RESULTS: Tc-99m TRODAT-1 SPECT-CT was performed on sixteen patients (10 females and 6 males) with a mean age of 55.2 years (range 26 to 75 years). Five patients exhibited normal scintigraphy findings, while eleven patients showed abnormal Tc-99m TRODAT-1 SPECT-CT results. The scintigraphy findings led to changes in therapeutic management for 81.3% of the patients. Additionally, 19% of the patients were referred for further evaluation with Fluorine-18 fluorodeoxyglucose PET to assist in diagnosing atypical Parkinsonian disease.
CONCLUSIONS: Tc-99m TRODAT-1 SPECT-CT is a readily available tool for assessing presynaptic dopamine transporters in patients with parkinsonism. This study demonstrated that Tc-99m TRODAT-1 SPECT-CT significantly impacts the diagnostic and therapeutic outcomes for patients with parkinsonism.
OBJECTIVES: This study evaluates the effective dose for common PET/CT scans at Penang Hospital, with a particular focus on the influence of patient weight on both PET and CT dose components. Additionally, the study assesses whether weight-based dose protocols can contribute to dose optimization.
METHODS: This retrospective study analyzed 1439 PET/CT scans performed at Penang Hospital. The effective dose was calculated using International Commission on Radiological Protection (ICRP) 103, 106, and 128 dose coefficients. Conversion factors used were 0.019 mSv/MBq for 18F-FDG, 0.0199 mSv/MBq for 68Ga-PSMA, and 0.021 mSv/MBq for 68Ga-DOTATATE. The CT dose component was estimated using the dose-length product (DLP) with an empirical conversion factor (k = 0.015 mSv·mGy-1·cm-1) for whole-body CT.
RESULTS: The total effective dose for 18F-FDG (head-to-thigh and head-to-feet) scans was 12.34 and 16.38 mSv, respectively. For 68Ga-PSMA and 68Ga-DOTATATE scans, the total effective dose was 11.55 and 12.00 mSv, respectively. A statistically significant increase in dose was observed in heavier patients due to increased administered activity and CT parameters (P
METHODS: After baseline PET, patients were randomly assigned to an induction chemotherapy regimen: modified oxaliplatin, leucovorin, and fluorouracil (FOLFOX) or carboplatin-paclitaxel (CP). Repeat PET was performed after induction; change in maximum standardized uptake value (SUV) from baseline was assessed. PET nonresponders (< 35% decrease in SUV) crossed over to the alternative chemotherapy during chemoradiation (50.4 Gy/28 fractions). PET responders (≥ 35% decrease in SUV) continued on the same chemotherapy during chemoradiation. Patients underwent surgery at 6 weeks postchemoradiation. Primary end point was pathologic complete response (pCR) rate in nonresponders after switching chemotherapy.
RESULTS: Two hundred forty-one eligible patients received Protocol treatment, of whom 225 had an evaluable repeat PET. The pCR rates for PET nonresponders after induction FOLFOX who crossed over to CP (n = 39) or after induction CP who changed to FOLFOX (n = 50) was 18.0% (95% CI, 7.5 to 33.5) and 20% (95% CI, 10 to 33.7), respectively. The pCR rate in responders who received induction FOLFOX was 40.3% (95% CI, 28.9 to 52.5) and 14.1% (95% CI, 6.6 to 25.0) in responders to CP. With a median follow-up of 5.2 years, median overall survival was 48.8 months (95% CI, 33.2 months to not estimable) for PET responders and 27.4 months (95% CI, 19.4 months to not estimable) for nonresponders. For induction FOLFOX patients who were PET responders, median survival was not reached.
CONCLUSION: Early response assessment using PET imaging as a biomarker to individualize therapy for patients with esophageal and esophagogastric junction adenocarcinoma was effective, improving pCR rates in PET nonresponders. PET responders to induction FOLFOX who continued on FOLFOX during chemoradiation achieved a promising 5-year overall survival of 53%.