Prediction of clinically significant prostate cancer by [68 Ga]Ga-PSMA-11 PET/CT: a potential tool for selecting patients for active surveillance.

PURPOSE: In our study, our aim was to investigate the role of [68 Ga]Ga-PSMA-11 PET /CT imaging in the diagnosis of clinically significant prostate cancer (csPCa) (ISUP GG 2 and higher) in patients initially diagnosed with ISUP GG 1 and 2 after prostate biopsy. MATERIALS AND METHODS: We retrospectively reviewed 147 patient records in whom [68 Ga]Ga-PSMA-11 PET/CT imaging was performed preoperatively. All patients were initially diagnosed with ISUP GG 1 and 2 PCa by biopsy. Final pathology reports were obtained after radical prostatectomy. The [68 Ga]Ga-PSMA-11 PET/CT images were evaluated to determine the PRIMARY score. Patients' mpMRI-PIRADS scores were also recorded when available and analyzed in correlation with the pathology results. RESULTS: For the 114 patients scored using PRIMARY, 19 out of 37 patients with scores of 1 and 2 (51%) were diagnosed with csPCa. Of the 77 patients with PRIMARY scores between 3 and 5, 64 (83%) had csPCa. Notably, every patient with a PRIMARY score of 5 had csPCa. PRIMARY scoring had a sensitivity of 77% and specificity of 58%, with a positive predictive value of 83%. A moderate correlation was observed between PRIMARY scores and ISUP GG (Rho = 0.54, p < 0.001). In contrast, the PIRADS score displayed a sensitivity and specificity of 86% and 25% respectively, with a positive predictive value of 68%. No substantial correlation was found between PIRADS and ISUP GG. Statistical analysis revealed a significant correlation between PRIMARY and ISUP GG (p < 0.001), but not between PIRADS and ISUP GG (p = 0.281). Comparatively, PRIMARY scoring was significantly more reliable than PIRADS scoring in identifying csPCa. CONCLUSION: [68 Ga]Ga-PSMA-11 PET/CT imaging is promising for distinguishing high-risk prostate cancer patients from those apt for active surveillance, potentially aiding in the identification of csPCa.

18F-FDG PET/MRI Image of Skin Metastasis of Ovarian Cancer.

Ovarian cancer is one of the deadliest tumors among women. It mostly metastasizes to the liver, pleura, lungs, and bones. We present a sixty-six-year-old patient with skin lesions. The patient who underwent biopsy due to skin lesions was diagnosed with ovarian cancer. 18F-fluorodeoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) performed for metastasis search shows widespread skin involvement, especially in the lower abdomen and legs. Skin involvement it ovarian cancer can be rarely seen, and in this article we would like to share 18F-FDG PET/MRI of skin involvement in ovarian cancer.

Rituximab in the management of retroperitoneal fibrosis: A single tertiary rheumatology care center experience.

AIM: To investigate the clinical and radiological outcomes and glucocorticoid-sparing effect of rituximab therapy in 13 patients with retroperitoneal fibrosis (RPF). METHODS: We analyzed the data of both glucocorticoid-naive and glucocorticoid-resistant RPF patients who were treated with rituximab. Demographic features, positron emission tomography computed tomography (PET-CT) findings, and clinical and histopathologic outcomes were collected retrospectively. RESULTS: We evaluated the data of 13 RPF patients (8M/5F). The median follow-up duration was 28 months (interquartile range [IQR] 24.5-55.5 months) and median age at the time of diagnosis was 50.8 years (IQR 46.5-54.5 years). PET-CT scans showed that following the rituximab therapy, the craniocaudal diameter of the RPF mass reduced from 74 mm (IQR 50.5-130 mm) to 52 mm (IQR 35-77 mm; p = .06), and periaortic thickness of the RPF mass reduced from 14 mm (5.5-21.9 mm) to 7 mm (4.5-11 mm; p = .12). The maximum standardized uptake value (based on body weight) of the RPF mass decreased from 5.8 (4.3-9.7) to 3.1 (2.8-5.3) after the therapy (p = .03). The number of patients with hydronephrosis reduced from 11 to 6 following rituximab therapy (p = .04). Before rituximab, nine patients received a median dose of 10 mg (IQR 0-27.5 mg) prednisolone per day. After the rituximab treatment, we discontinued prednisolone treatment for four out of nine patients and reduced the daily dose for the remaining patients. At the time of the final evaluation of the patients, the median prescribed prednisolone dose was 5 mg/day (IQR 2.5-7.5 mg/day; p = .01). CONCLUSION: Our study shows that rituximab may be a favorable treatment option for glucocorticoid-refractory RPF patients with high disease activity on PET-CT scans.

Bilateral Lymphadenopathy After COVID Vaccine in 18F-Choline PET/MRI Performed for Hyperparathyroidism.

ABSTRACT: We describe a case of a 56-year-old woman with primary hyperparathyroidism. 18F-Choline PET/MRI revealed incidental bilateral axillary lymphadenopathy with mild-moderate increased 18F-choline uptake. The patient had her first and third doses of COVID-19 vaccines from the left arm and second dose of vaccine from the right arm before PET examination.

SPECT/CT-based dosimetry of salivary glands and iodine-avid lesions following 131I therapy.

Objective: The purpose was to provide uptake and radiation dose estimates to salivary glands (SG) and pathologic lesions following radioiodine therapy (RIT) of differentiated thyroid cancer patients (DTC). Methods: A group of DTC patients (n = 25) undergoing 131I therapy joined this study with varying amounts of therapeutic activity. Sequential SPECT/CT scans were acquired at 4 ± 2, 24 ± 2, and 168 ± 3 h following administration of 3497-9250 MBq 131I. An earlier experiment with Acrylic glass body phantom (PET Phantom NEMA 2012 / IEC 2008) was conducted for system calibration including scatter, partial volume effect and count loss correction. Dose calculation was made via IDAC-Dose 2.1 code. Results: The absorbed dose to parotid glands was 0.04-0.97 Gy/GBq (median: 0.26 Gy/GBq). The median absorbed dose to submandibular glands was 0.14 Gy/GBq (0.05 to 0.56 Gy/GBq). The absorbed dose to thyroid residues was from 0.55 to 399.5 Gy/GBq (median: 21.8 Gy/GBq), and that to distal lesions ranged from 0.78 to 28.0 Gy/GBq (median: 3.12 Gy/GBq). 41% of the thyroid residues received dose > 80 Gy, 18% between 70-80 Gy, 18% between 40-70 Gy, and 23% has dose < 40 Gy. In contrast, 18% of the metastases exhibited a dose > 80 Gy, 9% between 40-60 Gy, and the dose to the vast majority of lesions (64%) was < 40 Gy. Conclusion: It was inferred that dose estimation after RIT with SPECT/CT is feasible to apply, together with good agreement with published 124I PET/CT dose estimates. A broad and sub-effective dose range was estimated for thyroid residues and distal lesions. Moreover, the current methodology might be useful for establishing a dose-effect relationship and radiation-induced salivary glands damage after RIT.

Hybrid Ga-68 prostate-specific membrane antigen PET/MRI in the detection of skeletal metastasis in patients with newly diagnosed prostate cancer: Contribution of each part to the diagnostic performance.

PURPOSE: Bone metastasis is essential in patients with prostate cancer (PCa) as it determines prognosis and survival. Hybrid PET/MRI allows simultaneous acquisition of PET and MRI data, thus combining the strength of both technologies allows the detection of bone marrow metastases that are missed by PET/CT. In this retrospective study, we aimed to evaluate the diagnostic efficiency of hybrid PET/MRI with Ga-68 prostate-specific membrane antigen (PSMA) in detecting skeletal metastases in newly diagnosed PCa patients and compared the effectiveness of stand-alone PSMA PET reviewing versus stand-alone whole-body (WB) MRI evaluation. We also investigated the effect of the interpretation of all PET/MR data together on clinical management. METHODS: We studied 74 newly diagnosed PCa patients who underwent PSMA PET/MRI for staging purposes. At first, PET and MRI were evaluated separately for bone lesions on a patient-and-lesion basis and then a further joint PSMA PET/MRI interpretation was made. RESULTS: Patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy analysis for bone metastasis was, respectively, 1.0, 0.83, 0.54, 1.0, 0.86 for PET; 0.75, 0.96, 0.81, 0.95, 0.93 for WB MRI and 0.91, 0.95, 0.78, 0,98, 0.94 for PET/MRI. The combined PET/MRI evaluation changed the clinical impact in 13.5% of patients (eight correct and two wrong decisions) compared to PET stand-alone interpretation. CONCLUSION: PSMA PET imaging showed superior sensitivity to WB MRI in detecting bone metastases in newly diagnosed PCa patients, whereas WB MRI has superior specificity and PPV. Furthermore, the specificity and PPV of joint PET/MRI evaluation are better than PSMA PET alone. Despite the longer acquisition period, adding WB MRI sequences to PSMA PET imaging appears beneficial for PCa patient management.

Simplification of dosimetry in 90Y-radioembolization therapy by dual planar images.

AIM: The purpose was to provide a practical and effective method for performing reliable 90Y dosimetry based on 99mTc-MAA and SPEC/CT. The impact of scatter correction (SC) and attenuation correction (AC) on the injected 90Y activity, lung shunt fraction (LSF) and the delivered dose to lung and liver compartments was investigated within the scope of the study. MATERIAL AND METHODS: Eighteen eligible patients (F: 3, M: 15) were subjected to 90Y therapy. 99mTc-MAA (111-222 MBq) was injected into the targeted liver, followed by whole-body scan (WBS) with peak-window at 140 keV (15% width) and one down-scatter window. SPECT/CT scan was subsequently acquired encompassing lung and liver regions. The LSFs were fashioned from standard WBS LSFwb (St), scatter corrected WBS LSFwb (Sc), only scatter corrected SPECT LSFspect (NoAC-SC) and SPECT/CT with attenuation and scatter correction LSFspect (AC-SC). The absorbed doses that would be delivered to tumor and injected healthy liver were estimated using different calculation modes involving AC-SC (SPECT/CT), NoAC-SC (SPECT), NoAC-NoSC+LSFwb (SC), AC-SC + LSFwb (St), and NoAC-NoSC+LSFwb (St). RESULTS: The average deviations (range) in LSF values between standard LSFwb (St) and those from SPECT/CT (AC-SC), SPECT (NoAC-SC), and LSFwb (SC) were - 50% (- 29/- 71), - 32% (- 8/- 67), and - 45% (- 13/80), respectively. The suggested 90Y activity (GBq/Gy) was decreased within a range of 2-11%, 1-9%, and 2-7% by using LSFspect (AC-SC), LSFspect (NoAC-SC), and LSFwb (SC), respectively. Overall, two-sample t-test yielded no statistically significant difference (p < 0.05) in the absorbed doses to tumor and injected healthy liver between AC-SC (SPECT) and the rest of approaches with/and without AC and SC. However, a statistically significant difference (p < 0.05) was demonstrated in the lung shunt fractions and lung doses due to AC and SC. The LSFs from scatter corrected planar images LSFwb (SC) exhibited well agreement (R2 = 0.92) with SPECT/CT (AC-SC) and there was no statistically significant difference (Pvalue > 0.05) between both methods. CONCLUSION: It was deduced that SPECT/CT with attenuation and scatter correction plays a crucial role in the measurements of lung shunt fraction and dose as well as the total number of 90Y treatments. However, the absorbed dose to tumors and injected healthy liver was minimally affected by AC and SC. Besides, a good agreement was observed between LSF datasets from SPECT/CT versus scatter corrected WBS that can be alternatively and effectively used in 90Y dosimetry.

18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging Appearance of Gastrointestinal Behcet's Disease.

Behcet's syndrome (BS) is a variable vessel vasculitis with multi-organ involvement. Recurrent episodes of oral and genital ulcers, papulopustular and erythema nodosum-like skin lesions, and arthritis are relatively more frequent, whereas uveitis, venous and arterial lesions, nervous system, and gastrointestinal involvement are less common, but are severe manifestations. The frequency of gastrointestinal involvement shows important variation between countries as more common in the Far East and the United States, and much less common in Turkey and the Middle East. The main clinical signs of gastrointestinal Behcet's disease include abdominal pain, diarrhea, blood in the stool, fever, and weight loss. Ulcers seen in the terminal ileum, cecum, and ascending colon are common endoscopic findings. Herein, we presented the positron emission tomography/magnetic resonance imaging findings of gastrointestinal involvement in BS.

Comparison of brain F-18 FDG PET/MRI with PET/CT imaging in pediatric patients.

BACKGROUND: Standardized uptake values (SUVs) are important indexes for evaluating the accuracy of disease diagnoses achieved via fluoro-18 deoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) and positron emission tomography/magnetic resonance imaging (PET/MRI). The purpose of this study is to describe normal cerebral FDG uptake in the pediatric population and compare SUVmax/mean results for brain images obtained from PET/CT and PET/MRI in neurologically healthy pediatric examinees. METHODS: This study included 20 patients who were < 18 years of age and were without intracranial malignancy and/or brain disorders. Patients underwent either PET/CT imaging (n = 10) or PET/MRI imaging (n = 10) after 70-80 min of F-18 FDG injection. The SUVmax and SUVmean for various brain regions were calculated and compared between sides and imaging modalities using with appropriate statistical tests. RESULTS: The median SUVmax/SUVmean values of the right-sided frontal, parietal, temporal, and occipital lobes were 8.63/ 6.18, 8.85 / 6.97, 6.88 / 4.99, and 11.06 / 7.02 in PET/CT, respectively, and 11.45 / 8.59, 10.16 / 8.47, 8.82 / 6.6, and 11.71 / 8.25 in PET/MRI, respectively. The median SUVmax/SUVmean values of the left-sided frontal, parietal, temporal, and occipital lobes were 9.05 / 6.86, 8.03 / 6.62, 6.49 / 4.77, and 10.6 / 7.73 in PET/CT, respectively, and 10.7 / 8.16, 11.06 / 7.88, 8.13 / 6.09, and 10.96 / 9.22 in PET/MRI, respectively. CONCLUSIONS: These results showed that there was no statistically significant difference in SUVs values between the two brain imaging modalities except from SUVmax value of left-sided parietal lobe and no asymmetric radiopharmaceutical uptake between the left and right brain regions or cerebellums in each modality, suggested that in brain imaging, PET/MRI can be used reliably instead of PET/CT.

Evaluation of F-18 DOPA PET/CT in the detection of recurrent or metastatic medullary thyroid carcinoma: comparison with GA-68 DOTA-TATE PET/CT.

OBJECTIVE: PET imaging with F-18 DOPA (FDOPA) and Ga-68 DOTATATE (TATE) shows the most promising results to detect medullary thyroid cancer (MTC) recurrence. We performed this comparative study to detect the site of recurrent or metastatic disease in MTC patients with elevated serum calcitonin (Ctn) and/or carcinoembryonic antigen (CEA) levels. METHODS: We studied 46 MTC patients (25 women, 21 men) with elevated Ctn and/or CEA levels during follow-up who had both FDOPA and TATE PET/CT scans for re-staging purposes. RESULTS: FDOPA PET imaging yielded an overall sensitivity of 86.8%, specificity of 100%, PPV of 100%, NPV of 61.5%, and accuracy of 89.1%, while TATE PET scan had the same values as 84.2%, 87.5%, 96.9%, 53.8%, and 84.6%, respectively, and there was no statistically significant difference between the two modalities with the exception of the specificity value that was higher for FDOPA imaging. In a subgroup of patients with overt Ctn or CEA elevation, sensitivity of FDOPA increased significantly, whereas TATE sensitivity did not change. FDOPA PET imaging was significantly superior in detecting liver and regional lymph node (LN) metastases, while TATE PET scan was significantly better in the skeletal metastases. Early FDOPA demonstrated 11 invisible lesions on late FDOPA. CONCLUSION: Both FDOPA and TATE PET/CT imaging are useful to localize recurrences in MTC patients. While TATE imaging is superior to reveal skeletal disease, FDOPA seems better in liver and regional LN metastases; therefore, the two modalities appear complementary in monitoring MTC patients with elevated serum Ctn and/or CEA levels.

Active Giant Cell Vasculitis Diagnosis with 68Ga PSMA PET/CT Imaging.

Vasculitis is a multisystem disease characterized by inflammation with infiltration of leukocytes into the blood vessels. Giant cell arteritis (GCA) is the most common form of vasculitis that mostly affects medium- and large-sized arteries. 18Fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is increasingly used to diagnose inflammation of large arteries in GCA. Galium-68 prostate-specific membrane antigen (PSMA) PET/CT has a vital role in the assessment of patients with prostate cancer for recurrence and metastasis of the disease. Various benign and non-prostate malignant conditions may give rise to increased PSMA uptake. Herein, we demonstrate that PSMA uptake can be seen in GCA.

The role of 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT in the follow-up of patients with medullary thyroid cancer.

OBJECTIVE: Medullary thyroid cancer (MTC) is an aggressive form of thyroid malignancy with local metastasis in 30%-50% of the cases and distant metastasis predominantly to lung, liver and skeleton in 13%-15% of patients. Identification of the lesion using imaging modalities is of crucial importance for disease management in the recurrent or metastatic MTC. In this study, we aimed to determine the efficacy of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid tyrosine-3-octreotate (68Ga-DOTATATE) PET/CT imaging in patients with MTC and to evaluate the relationship between imaging findings and serum tumor markers. MATERIALS AND METHODS: The records of MTC patients, who were treated and followed-up in our department between the years 2005 and 2018 were retrospectively analyzed. Seventy-three patients with MTC, who underwent either 68Ga-DOTATATE PET/CT (n=61) and/or 18F-FDG PET/CT (n=59) together with serum calcitonin (Ctn) and/or carcinoembryogenic antigen (CEA) measurement within 6 months period were included in the study. Gallium-68-DOTATATE PET/CT and 18F-FDG PET/CT scans performed within 6 months on the same patient (n=38) were analyzed separately for comparison of the efficacy of both modalities. RESULTS: The overall sensitivity of 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT were 72.4% and 88.1%, respectively in detecting recurrent or metastatic disease. In the group of patients, who had both 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT within 6 months interval (median: 1.14 months; range: 0.03 - 5.7 months), no significant difference was found in the overall sensitivity of both imaging modalities, however 68Ga-DOTATATE PET/CT was found to be more sensitive in detection of bone lesions compared to 18F-FDG PET/CT (P=0.005). CONCLUSION: Both 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT are efficient imaging modalities in detection of recurrent or metastatic disease in MTC patients. Gallium-68-DOTATATE PET/CT could be more beneficial in detection of bone metastases with respect to 18F-FDG PET/CT.

Importance of combined use of preoperative 18F-FDG PET/CT imaging and intraoperative 18F-FDG handheld gamma probe detection in recurrent papillary thyroid cancer.

Radio-guided surgery using an intra-operative positron emission tomography (PET) probe in recurrent thyroid cancer (RTC) can be a useful method for tumor localization, verification of complete excision and to decrease operation time. We describe a case of RTC whose serum thyroglobulin (Tg) level was 5.6ng/mL. Preoperative fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) revealed two focal abnormalities in the anterior tracheal and right upper mediastinal regions and a handheld gamma probe was used intraoperatively to identify the hot areas seen on PET scan. Postoperative 18F-FDG PET/CT imaging after tumor excision was normal. This case shows that recurrent tumor can be localized correctly using 18F-FDG PET/CT and a surgical gamma probe.

Correlation of SUVmax and Apparent Diffusion Coefficient Values Detected by Ga-68 PSMA PET/MRI in Primary Prostate Lesions and Their Significance in Lymph Node Metastasis: Preliminary Results of an On-going Study

Objectives: Gallium-68 (Ga-68) prostate specific membrane antigen (PSMA) positron emission tomography (PET) has been shown to be more accurate than multiparametric prostate magnetic resonance imaging (MRI) in detection of primary prostate lesions. Using hybrid PET/MRI we aim to detect the correlation between SUVmax and apparent diffusion coefficient (ADC) in primary prostate lesions and to assess their prognostic value in detection of lymph node (LN) metastasis. Methods: Twenty-six patients, who were diagnosed as having prostate cancer with biopsy and underwent Ga-68 PSMA PET/MRI together with biparametric prostate MRI (bpMRI) were included. SUVmax, SUVmean and ADC were recorded for index lesions drawing a region of interest (ROI) of 1 cm2 around the pixel with the highest SUVmax (ROI-1) and another ROI following borders of prostate tumor detected by bpMRI (ROI-2). Presence of LN metastasis was recorded according to PSMA PET/MRI Results: SUVmax was inversely correlated with ADC (ROI-1: p=0.010; ROI-2: p=0.017 for b=800). SUVmax and SUVmeans were both higher in patients with LN metastasis and ADC was lower in patients with LN metastasis for ROI-1. SUVmax cut-off value of 19.8 for ROI-1 and 20.9 for ROI-2 had sensitivity and specificity of 77.8% and 76.5%, respectively for detection of LN metastasis, whereas ADC (b=800) cut-off value of 0.92x10-3 mm2/s had sensitivity and specificity of 87.5% and 76.5%, respectively. SUVmax/ADC (b=800) ratio increased the sensitivity and specificity to 100% and 82.4%, respectively. Conclusion: SUV and ADC values are inversely correlated in primary prostate lesions and the combined use of both values increases the diagnostic accuracy of hybrid PET/MRI in the detection of primary prostate lesions.

Comparison of PERCIST and RECIST criteria for evaluation of therapy response after yttrium-90 microsphere therapy in patients with hepatocellular carcinoma and those with metastatic colorectal carcinoma.

OBJECTIVE: Yttrium-90 (Y) microsphere therapy has been increasingly used to treat hepatocellular carcinoma (HCC) and liver metastasis of colorectal cancer (mCRC). This study aims to compare two different criterias used for therapy response evaluation following Y therapy within the same group of patients. PATIENTS AND METHODS: A total of 21 patients with HCC and 19 patients with mCRC were included in this study, with 36 and 42 liver lesions, respectively. The lesions were evaluated before and after therapy by CT or MRI and fluorine-18 fluorodeoxyglucose (F-FDG) PET/CT. Several metabolic parameters were analyzed including maximum and mean standardized uptake values, peak standardized uptake value, metabolic tumor volume (MTV), and total lesion glycolysis. Tumor volume was determined using CT or MRI images for all lesions, and the applied activity was estimated to deliver 120±20 Gy for the treated lobe. Six weeks after Y microsphere therapy, F-FDG PET/CT scan was performed to evaluate tumor response using PERCIST and RECIST criteria. Overall survival was calculated using Kaplan-Meier method. RESULTS: A total of 78 liver lesions were treated without any major complication. The mean tumor volumes of HCC lesions calculated by CT or MRI before and after therapy were 84.38 and 86.62 cm, respectively. The average MTV of these lesions on PET images was calculated as 68.142 mm before therapy and 56.945 mm after treatment. In patients with mCRC, the mean tumor volume was 52.32 cm before therapy and 54.52 cm after therapy. The average MTV was calculated as 41.720 mm before and 44.967 mm after therapy for the same patient group. Response Evaluation Criteria In Solid Tumors (RECIST) and PET Response Criteria In Solid Tumors incompatibility was seen in seven of 36 lesions in HCC-diagnosed patients and seven of 42 lesions in patients with mCRC. The mean overall survival was calculated as 13.09 months in patients with HCC and 10.6 months in patients with mCRC. CONCLUSION: Y therapy response can be evaluated by both RECIST and European Organization for Research and Treatment of Cancer criteria. However, RECIST and European Organization for Research and Treatment of Cancer incompatibility can be seen. The anatomic methods for evaluating HCC response is relatively more accurate, whereas the metabolic parameters guided by PET/CT scan showed greater importance in response to evaluation of liver mCRC.

Comparison of Ga-68 PSMA positron emission tomography/computerized tomography with Tc-99m MDP bone scan in prostate cancer patients

Background/aim: The aim of our study was to compare Tc-99m MDP bone scan and Ga-68 PSMA PET/CT in terms of detection of bone metastasis in prostate cancer patients. Materials and methods: A total of 28 prostate cancer patients with bone scan and PSMA PET/CT performed within 90 days were retrospectively included in our analysis. All bone lesions were scored as negative (score-0), positive (score-1), or suspicious (score-2) for metastasis by two experienced nuclear medicine physicians. Both patient-based and region-based analyses were made for all osseous lesions. Results: On per-patient analysis; sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72.7%, 52.9%, 50%, 75%, and 60.7%, respectively, for bone scan and 90.9%, 100%, 100%, 94.4%, and 96.4%, respectively, for PSMA PET/CT. On per-region analysis; sensitivity, specificity, PPV, NPV, and accuracy were 76.2%, 80.9%, 57.1%, 91.1%, and 79.8%, respectively, for bone scan and 85.7%, 100%, 100%, 95.5%, and 95.4%, respectively, for PSMA PET/CT. Conclusion: Ga-68 PSMA PET/CT has higher sensitivity, specificity, and accuracy compared to bone scan in terms of bone metastasis detection in prostate cancer patients. Therefore, it might be the modality of choice for patients with suspicion for metastatic disease, despite negative bone scan and conventional imaging results

Diagnostic Capabilities of MRI Versus 18F FDG PET-CT in Postoperative Patients with Thyroglobulin Positive, 131I-negative Local Recurrent or Metastatic Thyroid Cancer.

BACKGROUND: The detection of recurrence or metastasis might be challenging in patients, who underwent total thyroidectomy and radioactive iodine therapy for Differentiated Thyroid Carcinoma (DTC), with increased serum Thyroglobulin (Tg) levels and negative 131I whole body scan (131I-WBS) results. AIMS: The purpose of this study was to compare the ability of Magnetic Resonance Imaging (MRI) and 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F FDG PET-CT) to detect recurrence or cervical and upper mediastinal metastases in postoperative DTC patients who had negative 131I-WBS despite elevated serum Tg levels. STUDY DESIGN: This study has a retrospective study design. METHODS: We evaluated cervical and upper mediastinal MRI and 18F FDG PET-CT of 32 postoperative patients with DTC (26 patients with papillary thyroid carcinoma and 6 patients with follicular thyroid carcinoma). RESULTS: We evaluated 44 lesions in 32 patients. For all lesions, the Positive Predictive Value, (PPV) Negative Predictive Value (NPV), sensitivity, specificity, and accuracy of MRI were 81.4%, 76.4%, 84.6%, 72.2%, and 79.5% respectively. The PPV, NPV, sensitivity, specificity, and accuracy of 18F FDG PET-CT were 100.0%, 85.7%, 88.4%, 100.0%, and 93.1%, respectively. CONCLUSION: Although we could not replace 18F FDG PET-CT, MRI might be used as an adjunct to 18F FDG PET-CT for the evaluation of recurrent or cervical and upper mediastinal metastatic thyroid cancers; however, MRI is inadequate for the detection of metastases in small lymph nodes.

Comparison of day 3 and day 5 thyroglobulin results after thyrogen injection in differentiated thyroid cancer patients.

BACKGROUND: It is necessary to stimulate serum thyroid-stimulating hormone (TSH) levels either endogenously by thyroid hormone withdrawal (THW) or exogenously by administration of recombinant human TSH (rhTSH) for radioactive iodine (RAI) therapy. Thyrotropin alfa (Thyrogen) has many advantages over THW. Radiation dose to laboratory staff while drawing blood for tests on the day 5 is one of the disadvantages of preferring Thyrogen. Our aim was to compare day 3 and day 5 blood test results after Thyrogen injections. MATERIAL AND METHOD: In our study, Thyrogen was preferred in 32 differentiated thyroid cancer patients with a mean age of 50.5 ± 12.3 years. Thyrogen was injected on day 1 and day 2 intramuscularly in all patients before I-131 was given on day 3. A total of 22 patients received 5 mCi RAI for ablation control scintigraphy and 10 patients received 100-250 mCi RAI for ablation or therapy (high-dose group). Blood tests were performed on day 3 and day 5 after Thyrogen injections. RESULTS: Mean TSH level was 98.1 mg/dl for day 3 and 29.5 mg/dl for day 5. In the diagnostic group, thyroglobulin (Tg) and anti-Tg levels were nearly the same on day 3 and day 5. In the therapy group, day 5 Tg levels were higher than day 3. CONCLUSION: After Thyrogen injection of two consecutive days, blood sampling might be enough on day 3. Day 5 blood sampling may not be necessary routinely for radiation protection of laboratory staff. For the diagnostic group, if Tg and anti-Tg is normal then 5 mCi imaging may not be necessary.

Orbital flourine-18-fluorodeoxyglucose positron emission tomography in patients with Graves' disease for evaluation of active inflammation.

OBJECTIVE: Prediction and early diagnosis of orbitopathy is needed in patients with Graves' disease, especially when radioiodine therapy is planned. Positron emission tomography/computerized tomography (PET/CT) using flourine-18-fluorodeoxyglucose (FDG) is an effective imaging modality in detection of inflammation, however, its ability to detect orbital inflammation has not been well studied. The aim of our study is to determine the ability of FDG PET/CT to detect orbital inflammation related with Graves' disease, identify active orbitopathy, predict the radioiodine-triggered orbitopathy, and find out the effects of radioiodine on orbital inflammation. MATERIALS AND METHODS: Total 31 Graves' disease patients and 17 controls were included. All Graves' disease patients underwent cranial FDG PET/CT imaging prior therapy. Radioiodine therapy and post-treatment PET/CT study was applied to 21 patients. PET/CT images of all examinees were evaluated, measuring extraocular muscle maximum standard uptake value (SUVmax) and muscle thickness. RESULTS: FDG uptake was increased in the majority of extraocular muscles in Graves' disease patients in comparison to controls and this increase was found to be irrelevant from muscle thickness. Extraocular muscle SUVmax values did not increase in Graves' orbitopathy patients who received radioiodine under corticosteroid prophylaxis. SUVmax level of all orbital rectus muscles were increased after radioiodine therapy in nonsmokers, whereas no increase was detected in smokers. CONCLUSION: FDG PET/CT may be helpful in detection of extraocular muscle inflammation and it may show ongoing orbitopathy in early stages of inflammation before anatomical changes occur.

FDG PET/CT in Peritoneal Metastasis From Prostate Cancer.

Prostate cancer is one of the leading causes of cancer death in men. The prognosis in prostate cancer is greatly worsened by the presence of metastases, which are most commonly found in bone, lung, liver, and brain. The peritoneum is an extremely uncommon metastatic site for prostate cancer, even in autopsy series. We present a case of FDG PET/CT demonstration of peritoneal metastasis from prostate cancer.