Natural history of prostate cancer (PCa) is extremely variable, as it ranges from indolent and slow growing tumors to highly aggressive histotypes. Genetic background and environmental factors co-operate to the genesis and clinical manifestation of the tumor and include among the others race, family, specific gene variants (i.e., BRCA1 and BRCA2 mutations), acute and chronic inflammation, infections, diet and drugs. In this scenario, remaining actual the clinical interest of bone scan (BS) in detecting skeletal metastases, an important role in diagnostic imaging may be also carried out by, positron emission tomography/computed tomography (PET/CT) and PET/magnetic resonance imaging (PET/MRI), which combine morphological information provided by CT and MRI with functional and metabolic data provided by PET acquisitions. With respect to PET radiotracers, being ancillary the usefulness of F-18 fluoro-deoxyglucose and not yet demonstrated the cost-effectiveness of F-18 Fluoride respect to BS, the main role is now played by choline derivatives, in particular by 11C-choline and 18F-fluorocholine. More recently, a greater interest for both diagnostic and therapeutic purposes has been associated with radiotracers directed to prostate-specific membrane antigen (PSMA), a transmembrane protein expressed on the cell surface, which showed high selective expression in PCa, metastatic lymph nodes and bone metastases. Several PSMA-targeted PET tracers have been developed many of which showing promising results for accurate diagnosis and staging of primary PCa and re-staging after biochemical recurrence, even in case of low prostate specific antigen values. In particular, the most widely used PSMA ligand for PET imaging is a ⁶⁸Ga-labelled PSMA inhibitor, ⁶⁸Ga-PSMA-HBED-CC (⁶⁸Ga-PSMA-11). ^99mTc-HYNIC-Glu-Urea-A for single photon emission computed tomography, and ¹⁷⁷Lu-PSMA-617 for radioligand therapy has also been applied in humans, with interesting preliminary results related to a possible theranostic approach. A potential role of PSMA radioligands in radio-guided surgery has also been proposed.

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Gallium-68 prostate-specific membrane antigen (Ga-68 PSMA) ligand (HBED-CC) is a new promising positron emission tomography (PET) tracer for prostate cancer. Intense renal parenchymal uptake is a physiologic finding on Ga-68 PSMA ligand PET images. Evaluation of kidneys in low intensity demonstrates excellent distribution of this radiotracer in renal parenchyma with excellent image quality and resolution. In this article, we present the Ga-68 PSMA ligand PET renal images of four patients with prostate cancer. In two patients, there is normal distribution of radiotracer, and in other two, there are renal cysts causing parenchymal defects.

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[¹⁸F] 2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography scan was performed on 45 children with autism to study the baseline pattern and age-related developmental changes in the brain metabolism. Median standardized uptake values (SUVs) were compared with published healthy control data. Results showed that, in contrary to control data, the median SUVs in children with autism decrease linearly with increase in age. As compared to controls, autism children below 5 years showed greater metabolism and older children showed lower metabolism. In autism group, comparison of absolute SUVs within different regions of the brain revealed relatively lower metabolism in amygdala, hippocampus, parahippocampal gyrus, caudate nucleus, cerebellum, mesial temporal lobe, thalamus, superior and middle temporal pole, and higher metabolic uptake in calcarine fissure and Heschl's gyrus. These results help in understanding the baseline metabolism and developmental changes of brain among different age groups in autism.

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Prostate-specific membrane antigen (PSMA) is a glycosylated type-II transmembrane protein highly expressed in certain tumor cells. To the best of our knowledge, this is the first case reported of an isolated well-differentiated hepatocellular carcinoma (HCC) strongly suspected on gallium-68 (⁶⁸Ga)-PSMA positron emission tomography/computed tomography (PET/CT), which was not well characterized both on magnetic resonance imaging (MRI) liver with Primovist as well as fluorine-18 (¹⁸F)-choline PET/CT. Our patient had previous prostate cancer and previously was imaged using ¹⁸F-choline PET/CT. The last scan showed an indeterminate segment VII hypodensity which was not significantly choline-avid. The lesion was initially stable on serial MRI scans but then showed growth from 1.0 to 1.5 cm. ⁶⁸Ga-PSMA PET/CT was performed. The lesion was intensely tracer-avid. This was surgically excised and histology confirmed the presence of well-differentiated HCC. Well-differentiated HCC can be optimally imaged using ⁶⁸Ga-PSMA PET/CT and further prospective studies are needed to look into the potential of this imaging modality.

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Previous observational studies using old qualitative methods have not clarified the role of amyloid positron emission tomography (PET) in the assessment of dementia. Given the moderately positive predictive value, the presence of amyloid deposition does not necessarily imply the diagnosis of dementia. Conversely, the absence of amyloid PET deposition has been shown to be useful in excluding the neurodegenerative pathology, irrespective of the aging process. We describe the clinical application of new innovative software recently developed to increase the sensitivity of this technique and to discriminate pathological deposition of cerebral amyloid from the age-related changes, reporting preliminary findings from a case-series study. In three different clinical profiles, we underline the need of integrating neuropsychological assessment and findings with this new PET scan and software that provide quantitative information of the cerebral amyloid and may increase the probability of rapid and accurate assessment of Alzheimer's disease. Although this amyloid quantification is promising, these preliminary results should be confirmed in future prospective studies with adequate sample size.

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Bronchobiliary fistula (BFF) is an abnormal communication between the biliary tree and airway. A patient usually presents with cough and bilioptysis, and at times, it poses diagnostic and therapeutic challenge. This case demonstrates the usefulness of cholescintigraphy with single-photon emission computerized tomography in diagnosing BFF in case of hydatid cyst of the liver.

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Radium 223 dichloride (Ra223) is the only targeted alpha therapy able to extend survival in patients with bone metastases from prostate cancer. Mechanism of action and data currently available focused mainly on osteoblastic metastases from prostate cancer. In our institution, a patient with breast cancer affected by osteolytic metastases was treated with off-label use of Ra223. The evaluation of the deposit areas of Ra223 showed a perfect overlap with the regions of osteolysis previously detected by scintigraphy, indicating a possible therapeutic effect. This case report is the first document attesting Ra223 deposit in osteolytic metastases opening new opportunity of therapeutic development for this radiopharmaceutical.

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Tumor thrombosis is a relatively uncommon complication of renal cell carcinoma (RCC), and its diagnosis has therapeutic and prognostic implication. Computerized tomography (CT) is the primary imaging modality for staging RCC, but it has low sensitivity to differentiate between tumor thrombus and bland or benign thrombus. 18-fluorodeoxyglucose positron emission tomography/CT (PET/CT) has a limited role in diagnosis and staging of RCC, but its diagnostic accuracy is considerably high for detection of metabolically active tumor thrombus. We are presenting a case of metastatic left-sided RCC with massive hypermetabolic tumor thrombus extending from left kidney to left renal vein and inferior vena cava giving an interesting “Suspension Bridge” appearance on PET/CT images.

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Birt–Hogg–Dubé (BHD) syndrome is an autosomal dominant genetic disorder characterized by small papular skin lesions (fibrofolliculomas) causing susceptibility to kidney cancer, renal and pulmonary cysts, spontaneous pneumothoraces, and several noncutaneous tumors. We report a case of a 67-year-old woman, with a previous history of right hemithyroidectomy for adenomatous lesion. She presented with a swelling in the right thyroid bed that on subsequent biopsy revealed features of metastatic carcinoma. 18F-fludeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) performed for the detection of primary malignancy showed increased high-grade metabolic activity in the right supraclavicular soft tissue mass extending into the superior mediastinum. Moreover, on low-dose CT, there have been bilateral renal interpolar cortical lesions with mild metabolic activity. Given the fact that the right neck mass was highly unlikely to represent renal metastases in the absence of widespread metastatic disease, surgical excision of the right neck mass was performed. The histology of the mass was in keeping with hurtle cell thyroid carcinoma. In regard to renal lesions, bilateral partial nephrectomy was performed, which was consistent with chromophobe renal cell carcinoma, raising the suspicion of BHD that was confirmed by the subsequent genetic evaluation. It is well established that 18F-FDG PET/CT study is not an optimal modality for evaluation of renal lesions. However, careful assessment of the CT features in conjunction with the associated metabolic activity of the 18F-FDG PET component increases the diagnostic accuracy of PET/CT.

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The objective of this study was to determine whether [¹⁸F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) scan could predict the pathological response in esoph neoadjuvant concurrent chemoradiation (NACCRT) and neoadjuvant chemotherapy (NACT). A randomized prospective study was carried out from March 2014 to October 2016; thirty patients of histopathologically proven, locally advanced, potentially operable carcinoma esophagus comprising both squamous carcinoma and adenocarcinoma were randomized into NACCRT and NACT arms equally. Both groups had pretreatment FDG-PET-computed tomography (CT) scan and repeat scan after 5–6 weeks of neoadjuvant therapy (NAT). The change in mean %Δmaximum standardized uptake value (%ΔSUVmax) was compared with tumor regression grade (TRG) in the postoperative histology. Patients with TRG 1–2 were deemed responders and 3–5 were nonresponders. Pathologic response was correlated with percentage change in [¹⁸F]-FDG uptake (%ΔSUVmax); receiver operating characteristics (ROC) analyses were done to assess sensitivity and specificity of FDG-PET to determine its diagnostic accuracy. The mean SUV in NACCRT group decreased from 15.47 ± 2.92 to 7.31 ± 4.07 (P < 0.001), while in NACT group, mean SUV decreased from 14.74 ± 3.95 to 8.60 ± 3.89 (P < 0.001). Comparison between NACCRT and NACT leads to mean SUV of 57.80 ± 22.40 and 45.92 ± 19.23, respectively (P = 0.13). In NACCRT and NACT, TRG had mean %ΔSUVmax values of 2.53 ± 1.25 and 2.93 ± 1.28 (P = 0.393). However, we found a statistically significant correlation between SUV% reduction and TRG (P = 0.002). ROC curve analysis for FDG-PET-CT suggested an area under the curve of 0.693 and sensitivity and specificity of 80% and 46.7%, respectively. NACCRT and NACT lead to a statistically significant reduction in mean %ΔSUVmax and with statistical significance correlation when compared with pathological response assessment. Hence, PET-CT can be used for differentiating responders and nonresponders to NAT.

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Neuroendocrine tumors (NETs) are a diverse group of tumors that often present late due to nonspecific symptoms. These tumors frequently express somatostatin receptors (SSRs), which allows for positron emission tomography/computed tomography (PET/CT) imaging with Ga-68-DOTATATE. In eligible patients, this may then be followed by peptide receptor radionuclide therapy (PRRT). Here, we report our initial results and experience with PRRT in a developing country, as one of the first groups to provide this therapy in South Africa. Eligible patients with confirmed inoperable NETs were recruited prospectively and treated with Lu-177-DOTATATE. Baseline imaging was performed with either single-photon emission CT- or PET-based SSR analogs, whereas follow-up was performed with ⁶⁸Ga-DOTATATE PET/CT 6 months post treatment completion. Interim treatment response evaluation was based on post therapy imaging of Lu-177-DOTATATE. A total of 48 patients with a mean age of 58 years were treated with PRRT, of whom 22 (46%) demonstrated stable disease, 20 (42%) demonstrated a partial response, and 6 (12%) demonstrated progressive disease. The median progression-free survival (PFS) was 20 months with an interquartile range (IQR)_25%–75%of 4.5–30 months. The median freedom from progression duration was 32 months with an IQR_25%–75%of 25–40 months, and the median overall survival was 10 months with an (IQR)_25%–75%of 5–24 months. Our subgroup analysis demonstrated an inverse association between metabolic tumor volume with PFS, which requires further validation. In conclusion, PRRT with Lu-177-DOTATATE resulted in a median PFS of 20 months in patients with inoperable NETs in the absence of significant side effects.

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