FDG-PET/CT in infections: the imaging method of choice?

[No abstract available

Pheochromocytomas/Paragangliomas and two cases

Pheochromocytomas are catecholamine-producing neuroendocrine tumours that arise from the adrenal medulla or extramedullary pheochromoblasts with highly variable clinical presentation, including episodes of headache, sweating, palpitations and hypertension. Due to the non-specificity of the symptoms there is usually a delay between the onset of symptoms and the final diagnosis. To make a firm diagnosis, biochemical testing of the blood (catecholamines) or urine (metanephrines and VMA) are mandatory. Many stimuli increase circulating catecholamines and metabolites and must receive due attention to prevent false-positive results. Therapeutically, surgery is the gold standard. To minimise complications during and post surgery the lesion(s) should be carefully localised via imaging studies. Adequate pre- and postoperative medical treatment is important. The history, diagnosis and therapy of two patients - the one with a paraganglioma of the organ of Zuckerkandl, the other with a intra thoracic paraganglioma are presented. South African Family Practice Vol. 49 (5) 2007: pp. 42-4

The use of 18F-FDG PET/CT metabolic parameters in predicting overall survival in patients undergoing restaging for malignant melanoma

Malignant melanoma is one of the more aggressive cancers in the skin, with an increasing incidence every year. Melanoma has a better prognosis if diagnosed early and survival tends to decrease once the disease has metastasized. Positron emission tomography (PET) with 2-[18F]fluoro2-deoxy-D-glucose (18F-FDG) has been used extensively over the past two decades in staging and assessing responses to therapy in patients with melanoma. Metabolic PET parameters have been demonstrated to be independent prognostic factors for progression-free survival (PFS) and overall survival (OS) in different malignancies, melanoma included. In our study, we evaluated the metabolic parameters of 18F-FDG PET/CT (flourodeoxyglucose positron emission tomography/computed tomography) in predicting the overall survival in patients with malignant melanoma who presented for restaging. Metabolic PET parameters (maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG)) of the primary tumor, as well as whole-body MTV and TLG of the metastatic disease, were measured. Survival curves for OS were constructed and mortality rates were determined using the different PET variables. Forty-nine patients who presented for a PET/CT restaging in melanoma were included in this study. We found that non-survivors had significantly higher median MTV (11.86 cm3 vs. 5.68 cm3 ; p-value = 0.022), TLG (3125 vs. 14; p-value = 0.0357), whole-body MTV (53.9 cm3 vs. 14.4 cm3 ; p-value = 0.0076) and whole-body TLG (963.4 vs. 114.6; p-value = 0.0056). This demonstrated that high MTV and TLG values of the primary tumor and whole-body TLG as quantified by 18F-FDG PET/CT were prognostic factors for overall survival. The findings may potentially guide clinicians in decision making and identifying patients with a poorer prognosis.https://www.mdpi.com/journal/diagnosticsdm2022Nuclear Medicin

[68 Ga]Ga-FAPi PET/CT vs [18F]F-FDG PET/CT in various cancers: Initial experience

https://drive.google.com/file/d/1XJSXXwXb9eK56-UgDlrw69lIXleOi6IC/view?usp=sharinghttps://drive.google.com/drive/folders/1KrqkKx5LQG9uPrY6_gsr7jjg7XEVv_To?usp=sharinghttps://drive.google.com/drive/folders/1fpqwRHsic5hXdQnMQKRDXvm-_DzlLUfS?usp=sharin

Appropriate indications for positron emission tomography/computed tomography, 2015

These recommendations are intended to serve an important and relevant role in advising referring physicians on the appropriate use of 18F-fluorodeoxyglucose (18F-FDG) and non-18F-FDG positron emission tomography/computed tomography (PET/CT), which can be a powerful tool in patient management in oncology, cardiology, neurology and infection/inflammation. PET is a non-invasive molecular imaging tool that provides tomographic images and quantitative parameters of perfusion, cell viability, proliferation and/or metabolic activity of tissues. These images result from the use of different substances of biological interest (sugars, amino acids, metabolic precursors, hormones) labelled with positron-emitting radionuclides (PET radiopharmaceuticals). Fusion of the aforementioned important functional information with the morphological detail provided by CT as PET/CT provides clinicians with a sensitive and accurate one-step whole-body diagnostic and prognostic tool, which directs and changes patient management. Hence PET/CT is currently the most widely used molecular imaging technology for a patient-tailored treatment approach. In these recommendations we outline which oncological and non-oncological indications are appropriate for PET/CT. Once each combination of pathology and clinical indication is defined, a recommendation is given as: 1. Recommended; 2. Recommended in select cases; 3. May be considered; or 4. Not recommended.http://www.samj.org.zaam2016Nuclear Medicin

A prospective investigation of tumor hypoxia imaging with 68Ga-nitroimidazole PET/CT in patients with carcinoma of the cervix uteri and comparison with 18F-FDG PET/CT : correlation with immunohistochemistry

Hypoxia in cervical cancer has been associated with a poor prognosis. Over the years 68Ga labelled nitroimidazoles have been studied and have shown improved kinetics. We present our initial experience of hypoxia Positron Emission Tomography (PET) imaging in cervical cancer with 68Ga-Nitroimidazole derivative and the correlation with 18F-FDG PET/CT and immunohistochemistry. Twenty women with cervical cancer underwent both 18F-FDG and 68Ga-Nitroimidazole PET/CT imaging. Dual-point imaging was performed for 68Ga-Nitroimidazole PET. Immunohistochemical analysis was performed with hypoxia inducible factor-1 (HIF-1 ). We documented SUVmax, SUVmean of the primary lesions as well as tumor to muscle ratio (TMR), tumor to blood (TBR), metabolic tumor volume (MTV) and hypoxic tumor volume (HTV). There was no significant difference in the uptake of 68Ga-Nitroimidazole between early and delayed imaging. Twelve patients had uptake on 68Ga-Nitroimidazole PET. Ten patients demonstrated varying intensities of HIF-1 expression and six of these also had uptake on 68Ga-Nitroimidazole PET. We found a strong negative correlation between HTV and immunohistochemical staining (r = 0.660; p = 0.019). There was no correlation between uptake on PET imaging and immunohistochemical analysis with HIF-1 . Two-thirds of the patients demonstrated hypoxia on 68Ga-Nitroimidazole PET imaging.https://www.mdpi.com/journal/jcmam2022Nuclear Medicin

Development of a clinical decision model for thyroid nodules

<p>Abstract</p> <p>Background</p> <p>Thyroid nodules represent a common problem brought to medical attention. Four to seven percent of the United States adult population (10–18 million people) has a palpable thyroid nodule, however the majority (>95%) of thyroid nodules are benign. While, fine needle aspiration remains the most cost effective and accurate diagnostic tool for thyroid nodules in current practice, over 20% of patients undergoing FNA of a thyroid nodule have indeterminate cytology (follicular neoplasm) with associated malignancy risk prevalence of 20–30%. These patients require thyroid lobectomy/isthmusectomy purely for the purpose of attaining a definitive diagnosis. Given that the majority (70–80%) of these patients have benign surgical pathology, thyroidectomy in these patients is conducted principally with diagnostic intent. Clinical models predictive of malignancy risk are needed to support treatment decisions in patients with thyroid nodules in order to reduce morbidity associated with unnecessary diagnostic surgery.</p> <p>Methods</p> <p>Data were analyzed from a completed prospective cohort trial conducted over a 4-year period involving 216 patients with thyroid nodules undergoing ultrasound (US), electrical impedance scanning (EIS) and fine needle aspiration cytology (FNA) prior to thyroidectomy. A Bayesian model was designed to predict malignancy in thyroid nodules based on multivariate dependence relationships between independent covariates. Ten-fold cross-validation was performed to estimate classifier error wherein the data set was randomized into ten separate and unique train and test sets consisting of a training set (90% of records) and a test set (10% of records). A receiver-operating-characteristics (ROC) curve of these predictions and area under the curve (AUC) were calculated to determine model robustness for predicting malignancy in thyroid nodules.</p> <p>Results</p> <p>Thyroid nodule size, FNA cytology, US and EIS characteristics were highly predictive of malignancy. Cross validation of the model created with Bayesian Network Analysis effectively predicted malignancy [AUC = 0.88 (95%CI: 0.82–0.94)] in thyroid nodules. The positive and negative predictive values of the model are 83% (95%CI: 76%–91%) and 79% (95%CI: 72%–86%), respectively.</p> <p>Conclusion</p> <p>An integrated predictive decision model using Bayesian inference incorporating readily obtainable thyroid nodule measures is clinically relevant, as it effectively predicts malignancy in thyroid nodules. This model warrants further validation testing in prospective clinical trials.</p

Biodistribution and dosimetry of 195mPt-cisplatin in normal volunteers

195mPt-cisplatin is regarded as a promising imaging agent for optimizing dosage in patients receiving cisplatin chemotherapy. We investigated the whole-body distribution and radiation dosimetry of 195mPt-cisplatin in humans. Methods: Whole-body scans were obtained up to 144 h after intravenous injection of 112.4 MBq 195mPt-cisplatin in each of five subjects. Blood samples were taken at various times up to 144 h after injection. Urine was collected up to 114 h after injection for calculation of renal clearance and wholebody clearance. Time/activity curves were generated by fitting the organ-specific geometric mean counts, obtained from regions of interest, on the respective images as a function of the time after injection. OLINDA software package was applied to calculate the absorbed radiation dose for various organs. Results: Most of the activity (32 ± 4%) was excreted in the urine during the first 5 h. The effective clearance half-life derived from extrapolation of the whole-body curve was 40 hours (1.7 days). On average, the highest dose was received by the kidneys (mean dose received 2.68 ± 1.5 mGy/MBq), followed by the spleen (mean dose received 1.6 ± 0.8 mGy/MBq) followed by the liver (mean dose received 1.45 ± 0.38 mGy/MBq). The estimated mean effective dose for the adult subject was 0.185 ± 0.034 mSv/MBq. Conclusion: 195mPt-cisplatin proved a safe radiopharmaceutical with a favourable biodistribution for early and delayed imaging of pathology above the diaphragm. The ED obtained was 0.185 ± 0.034 mSv/MBq. The highest organ dose was received by the kidneys (2.68 ± 1.5 mGy/MBq)