ABSTRACT
BACKGROUND: Prostate cancer (PC) is the second-most common cause of cancer.68Ga-prostate-specific membrane antigen (PSMA)-11 positron-emission tomography/computed tomography (PET/CT) scan help in accurate staging of PC owing to its high PSMA avidity and specificity. The aim of this prospective observational study was to determine the incremental value of Ga-68 PSMA-11 PET/CT over multiparametric magnetic resonance imaging (mpMRI) in the locoregional staging of intermediate- and high-risk PC using histopathology from radical prostatectomy specimens as a gold standard. MATERIALS AND METHODS: This was a prospective study, including 35 patients with biopsy-proven prostate carcinoma. All the patients underwent whole-body Ga-68 PSMA-11 PET/CT scans along with mpMRI including a dedicated pelvic imaging protocol within a time window of ± 10 days. The reference standard was based on histopathological results, postprostatectomy. RESULTS: All 35 patients showed Ga-68 PSMA-11-avid disease, of which 29 underwent radical prostatectomy, one underwent radiation therapy, and five did not undergo surgery owing to metastases. A total of 52 PC lesions were detected in 29 patients on histopathology. Of 52 lesions, 29 lesions were identified in prostate parenchyma and 23 were extraprostatic lesions on histopathology. Ga-68 PSMA-11 PET/CT detected a total of 45 lesions, of which 29 lesions were located within the prostate parenchyma and 16 were representative of extraprostatic lesions. mpMRI detected a total of 36 lesions, of which 29 lesions were located within the prostate parenchyma and seven were representative of extraprostatic lesions. The overall sensitivity of 68Ga-PSMA PET/CT and mpMRI in the detection of lesions was 86.2% and 68.6%, respectively. However, the overall specificity was 94.7% and 89.1% for 68Ga-PSMA and mpMRI, respectively. CONCLUSION: Ga-68 PSMA-11 PET/CT provided superior locoregional preoperative staging of PC as compared to mpMRI in intermediate- and high-risk PC patients.
ABSTRACT
BACKGROUND: Insulinoma is an islet-cell neoplasm that secretes insulin. It is usually localized to the pancreas and is often the most common cause of endogenous hyperinsulinemic hypoglycaemia in non-diabetic adult patients. Surgical excision with a curative intent is the standard modality of treatment, and it requires precise localization of tumor tissue. Ga-68 DOTA-exendin-4 PET/CT scan is a clinically reasonable and sensitive scan for the identification of insulinoma. The aim of this prospective cohort study was to determine the overall accuracy of Ga-68 DOTA-exendin-4 PET/CT scan in the detection of insulinoma. MATERIALS AND METHODS: Eight patients with fasting hyperinsulinemic hypoglycaemia with neuroglycopenic symptoms were enrolled in this study which was conducted during October 2016 to October 2017. Whole body PET/CT scan was performed on a Philips time of flight PET/CT scanner, 60 minutes after injection of Ga-68 DOTA-exendin-4 (and also Ga-68 DOTANOC). The imaging findings were compared to the histopathological diagnosis in six out of eight patients and to subsequent follow up in the remaining two patients who did not undergo surgery. RESULTS: The sensitivity of Ga-68 DOTA-Exendin-4 PET/CT scan in insulinoma detection was found to be 75%. CONCLUSION: Ga-68 DOTA-Exendin-4 PET/CT scan is highly sensitive for identification and exact localization of insulinoma which can guide better surgical exploration. However, randomised controlled trials are needed to assess the accuracy of Ga-68 DOTA-Exendin PET/CT scan in localization of insulinoma.
ABSTRACT
OBJECTIVE:: Two radiosensitizing chemotherapeutic drugs, capecitabine (CAP) and temozolomide (TEM), are administered concurrently to enhance the therapeutic efficacy of peptide receptor radionuclide therapy (PRRT). This study aims to assess the biodistribution and normal-organ and tumor radiation dosimetry for Lu-177 DOTATATE administered concurrently with CAP/TEM. METHODS:: 20 patients with non-resectable histologically confirmed gastroenteropancreatic neuroendocrine tumors with normal kidney function, a normal haematological profile and somatostatin receptor expression of the tumor lesions, as scintigraphically assessed by a Ga-68 DOTANOC scan, were included in two groups-case group (n = 10) and control group (n = 10). Patients included in case group were those who were advised concomitant CAPTEM therapy by the treating medical oncologist. Patients were administered CAP orally at a dose of 600mg m-2 bovine serum albumin twice a day for 14 days starting 9 days prior to PRRT and oral TEM as a single dose at a dose of 75 mg m-2 was given concurrently for the last 5 days commencing on the day of PRRT (days 9-14). In the control group, patients were treated with Lu-177 DOTATATE only. For PRRT, 6.4 GBq-7.6 GBq (173-207 mCi) of Lu-177 DOTATATE was administered as infusion into each patient over 10-15 min in a solution with positively charged amino acids for renal protection. Dosimetric calculations were done using the HERMES software. RESULTS:: Physiological uptake of Lu-177 DOTATATE was seen in all patients in liver, spleen kidneys, and bone marrow. Radiation absorbed doses (mean ± standard deviation) were obtained as 0.29 ± 0.12 mGy/MBq for kidneys, 0.30 ± 0.18 mGy/MBq for liver, 0.63 ± 0.37 mGy/MBq for spleen, 0.019 ± 0.001 mGy/MBq for bone marrow and 3.85 ± 1.74 mGy/MBq for tumours in the case group and they were 0.31± 0.26, 0.24 ± 0.14, 0.64 ± 0.42, 0.017 ± 0.016, 5.6 ± 11.27 mGy/MBq in kidneys, liver, spleen, bone marrow and neuroendocrine tumour, respectively, in the control group. Mann-Whitney U test between the variables of two groups showed an insignificant difference (p > 0.05). CONCLUSIONS:: The authors demonstrated no significant difference between the tumor and organ doses with Lu-177 DOTATATE in the patients treated with and without concomitant chemotherapy. ADVANCES IN KNOWLEDGE:: To our knowledge, this is the first dedicated study exhibiting dosimetric analysis in patients undergoing PRRT in combination with chemotherapy.
