The role of baseline Ga-68 DOTATATE positron emission tomography/computed tomography in the prediction of response to fixed-dose peptide receptor radionuclide therapy with Lu-177 DOTATATE.

BACKGROUND/AIM: To describe the role of baseline gallium (Ga)-68 DOTATATE positron emission tomography (PET)/computed tomography (CT) in the prediction of the response to peptide receptor radionuclide therapy (PRRT) using lutetium (Lu)-177 DOTATATE. MATERIALS AND METHODS: Analysis was made of baseline Ga-68 DOTATATE PET/CT images of 29 patients (17 females and 12 males; mean age: 50.7 ± 14.6 years) with metastatic neuroendocrine tumors who received PRRT with Lu-177 DOTATATE. Maximum standardized uptake values (SUVmax) of reference lesions and their ratios to physiological uptake organs were calculated. The relationship between these values and the radiological response was analyzed. RESULTS: Partial response was observed in 8 (28%) patients, stable disease in 18 (62%) patients, and progressive disease in 3 (10%) patients. Mean SUVmax of reference lesions was calculated as 23.8 ± 20.5 (min-max: 5.1-87.3). There was no significant correlation between radiological responses and SUVmax of reference lesions and their ratios to other organs. CONCLUSION: Baseline Ga-68 DOTATATE PET/CT helps to show somatostatin receptor expression status and disease stage in patients who are candidates for PRRT. However, SUVs do not have a role in the prediction of treatment response.

Demonstration of Response to Androgen Deprivation Therapy by 68Ga-PSMA PET/CT.

We present pretreatment and posttreatment Ga-PSMA PET/CT images of a 68-year-old man with metastatic prostate cancer who is a responder to androgen deprivation therapy.

Widespread Metastatic Prostate Carcinoma Shown by 68Ga-PSMA PET/CT.

We present the F-FDG and Ga prostate-specific membrane antigen PET/CT images of a 61-year-old patient with a newly diagnosed prostate carcinoma (4 + 4 Gleason score) and high serum prostate-specific antigen levels (460 ng/mL). In F-FDG PET/CT, minimal uptake was demonstrated in the prostatic mass without any accompanying pathological uptake. However, Ga prostate-specific membrane antigen PET/CT revealed multiple pathological uptake in the lung nodules, mediastinal nodes, abdominal-pelvic lymph nodes, bone lesions, and prostatic mass.

Radioembolization with (90)Y resin microspheres for intrahepatic cholangiocellular carcinoma: prognostic factors.

AIM: To investigate the prognostic factors that predict overall survival after radioembolization in patients with cholangiocellular carcinoma. METHODS: The study comprised 16 patients who received radioembolization with Y(90) resin microspheres for cholangiocarcinoma. The statistical relationships between overall survival after radioembolization and age, number, dimension and fluorodeoxyglucose (FDG) avidity of liver lesions, liver tumor load, presence of extrahepatic metastases, and radiological response were analyzed. RESULTS: Mean 1.7 ± 0.1 GBq(90)Y microspheres were administered to a total of 16 patients (mean age: 55.37 ± 17.7; 8 males, 8 females). Mean AST, ALT, and total bilirubin levels were calculated as 35 ± 15, 40 ± 37 IU/L, and 0.77 ± 0.37 mG/dL, respectively. In 6 patients, 1 liver lesion was determined, in 2 patients ≤ 5, and in 8 patients >5, with dimensions varying between 12 and 120 mm. The liver lesions of 13 patients were FDG avid (mean SUVmax: 7.4 ± 2.2). Extrahepatic metastases were demonstrated in 5 patients. Tumor load of 4, 8, and 4 patients was calculated as <25, 25-50, and >50%, respectively. Five patients were responsive to treatment. During the follow-up period of 243 (range 98-839) days, 12 patients died. In Cox-regression analysis, FDG avidity (p = 0.02), the dimensions (p = 0.03) of the liver lesion, tumor load (p = 0.02), and radiological response (p = 0.01) were found to be statistically significant parameters predictive of overall survival after radioembolization (p = 0.006). CONCLUSION: FDG avidity and the dimension of the largest liver lesion, tumor load, and radiological response are prognostic factors in patients receiving radioembolization for cholangiocellular carcinoma. Patients with lower tumor load, FDG-negative tumors, and smaller tumors seem to survive longer after radioembolization.

The Role of 18F-FDG PET/CT in the Primary Staging of Gastric Cancer.

OBJECTIVE: The aim of this study is to explore the role of 18F-FDG PET/CT in the primary staging of gastric cancer in the comparison of ceCT as routine staging method and evaluate influencing parameters of 18F-FDG uptake. METHODS: Thirty-one patients (mean age: 58.9±12.6) who underwent 18F-FDG PET/CT for primary staging of gastric cancer between June 2011 and June 2012 were included to the study. 18F-FDG PET/CT findings were compared with pathological reports in patients who underwent surgery following PET/CT. 18F-FDG PET/CT findings of primary lesions, lymph nodes and adjacent organs were compared with ceCT findings and pathological reports. Since 6 patients were accepted as inoperable according to 18F-FDG PET/CT and/or ceCT and/or laparotomy and/or laparoscopy findings, pathological confirmation could not be possible. RESULTS: In the postoperative TNM staging of patients, while 1 (4%), 1 (4%), 4 (16%), 2 (8%), 12 (48%) and 5 (20%) patients were staged as T0, Tis, T1, T2, T3 and T4, respectively, 8 (32%), 6 (24%), 6 (24%) and 5 (20%) patients were N0, N1, N2 and N3 respectively. 18F-FDG PET/CT was totally normal in 2 patients. While primary tumors were FDG avid in 27 patients, in 17 and 6 patients FDG uptake was observed in perigastric lymph nodes and distant organs, respectively. Mean SUVmax of FDG avid tumors was calculated as 13.49±9.29 (3.00-44.60). However, SUVmax of lymph nodes was computed as 9.28±6.92 (2.80-29.10). According to sub-analysis of histopathological subtypes of primary tumors, SUVmax of adenocarsinomas was calculated as 15.16 (3.00-44.60), of signet ring cells as 9.90 (5.50-17.70), of adenocarcinomas with signet ring cell component as 11.27 (6.20-13.90) (p=0.721). In the comparison with histopathological examination while ceCT was TP, TN, FN in 23, 1 and 1 patients, 18F-FDG PET/CT was TP, FP, FN in 20, 1 and 4 patients, respectively. Sensitivity, specificity, accuracy, PPD and NPV of ceCT in the detection of lymph node metastasis was calculated as 83.3%, 75%, 80%, 87.5% and 66.6%, respectively. These parameters for 18F-FDG PET/CT were 64.7%, 100%, 76%, 100% and 57.1%. CONCLUSION: Despite lower sensitivity than ceCT, diagnostic power of 18F-FDG PET/CT in the preoperative staging of gastric cancer is acceptable. Because of its high PPV, it might be beneficial in the evaluation of patients with suspected lymph nodes. The role of 18F-FDG PET/CT seems to be limited in the early stage and signet ring cell carcinomas due to lower 18F-FDG uptake.

18F-NaF Positive Bone Metastases of Non 18F-FDG Avid Mucinous Gastric Cancer.

Detection of gastric cancer bone metastasis is crucial since its presence is an independent prognostic factor. In this case report, we would like to present 18F-NaF positive bone metastases of non 18F-FDG avid gastric mucinous cancer.

The role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in the primary staging of rectal cancer.

BACKGROUND: In this study we aimed to determine the need for 18F-flourodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the preoperative staging of rectal carcinoma in our large patient group according to level and location of tumor. METHOD: Totally, 97 patients diagnosed with primary rectal adenocarcinoma between May 2009 and July 2011 were included in the study. Preoperative staging was performed by evaluating contrast-enhanced thoracic, abdominal, and pelvic computed tomographies. After staging by conventional methods, all patients underwent an 18F-FDG PET/CT. In all cases, the relationship between 18F-FDG uptake and gender, tumor height at the anal canal, localization in the rectal wall, plasma carcinoembryonic antigen levels, histopathological tumor type, and tumor stage were examined. RESULTS: While the ceCT was normal in 4 (4%) patients, it was positive for the rectum in 93 (95%), pelvic lymph nodes in 22 (22%), and distant metastases in 14 (14%) (liver (8), lung (8), bone (2), distant lymph nodes (6), and uterus (1)). Using computed tomography, disease stages were determined as stage 0, 1, 2, 3, and 4 in 4, 8, 48, 23, and 14 patients, respectively; 18F-FDG PET/CT was normal in two (2%) patients. The mean SUVmax of FDG-positive rectal tumors was calculated as 17.31 ± 9.37. Additionally, 18F-FDG uptake was seen in pelvic lymph nodes in 15 (15%) patients and in distant organs in 24 (24%) patients (liver (9), lung (12), bone (5), distant lymph nodes (11), uterus (1), and sigmoid colon (1)). According to an 18F-FDG PET/CT, 2, 7, 47, 20, and 21 patients were staged as stage 0, 1, 2, 3, and 4, respectively. In 14 patients (14.4%), the stage of the disease was either changed, and there was a need to make adjustments to the patient's treatment strategy (n = 10), or the type of operation was changed (n = 4). In seven patients (0.7%), findings from 18F-FDG PET/CT images did not require any changes of the treatment plan. CONCLUSION: F-FDG PET/CT provides new findings in addition to conventional techniques in the staging of primary rectal cancer. These findings could change the patients' treatment strategies.