Visceral Hepatic Leishmaniasis in a Melanoma Patient in FDG-PET.

BACKGROUND: Leishmaniasis is caused by protozoans that depend on female phlebotomine sandflies as vectors. The natural habitat of these sandflies is changing due to climatic changes, affecting the immunocompromised population, as more patients get immunocompromised due to cancer therapy in the present time. CASE REPORT: We report the case of a 72-year-old patient with melanoma in whom we found visceral leishmaniasis mimicking hepatic metastasis in routine FDG-PET/CT. The patient was hospitalised due to fever and pancytopenia in the general hospital Steyr. The diagnosis was made by biopsy of the iliac crest with cytological study and polymerase chain reaction. After treatment with amphotericin B, the patient recovered and tests became negative, including FDG-PET/CT. Because of climate change and the increasing use of immunomodulatory medication, our awareness of such findings should grow. CONCLUSION: New pitfalls in diagnosis and surveillance of cancer patients because of altered environmental conditions and immunocompromised patients have to be taken into account.

Lack of association between cortical amyloid deposition and glucose metabolism in early stage Alzheimer´s disease patients.

BACKGROUND: Beta amyloid (Aß) causes synaptic dysfunction leading to neuronal death. It is still controversial if the magnitude of Aß deposition correlates with the degree of cognitive impairment. Diagnostic imaging may lead to a better understanding the role of Aß in development of cognitive deficits. The aim of the present study was to investigate if Aß deposition in the corresponding brain region of early stage Alzheimer´s disease (AD) patients, directly correlates to neuronal dysfunction and cognitive impairment indicated by reduced glucose metabolism. PATIENTS AND METHODS: In 30 patients with a clinical phenotype of AD and amyloid positive brain imaging, 2-[18F] fluoro-2-deoxy-d-glucose (FDG) PET/CT was performed. We extracted the average [18F] flutemetamol (Vizamyl) uptake for each of the 16 regions of interest in both hemispheres and computed the standardized uptake value ratio (SUVR) by dividing the Vimazyl intensities by the mean signal of positive and negative control regions. Data were analysed using the R environment for statistical computing and graphics. RESULTS: Any negative correlation between Aß deposition and glucose metabolism in 32 dementia related and corresponding brain regions in AD patients was not found. None of the correlation coefficient values were statistically significant different from zero based on two-sided p- value. CONCLUSIONS: Regional Aß deposition did not correlate negatively with local glucose metabolism in early stage AD patients. Our findings support the role of Aß as a valid biomarker, but does not permit to conclude that Aß is a direct cause for an aberrant brain glucose metabolism and neuronal dysfunction.

Serotonin 1A receptor density measured by F18-Mefway PET/CT in mesiotemporal cortex and raphe does not discriminate therapeutic response in patients with major depressive episode.

BACKGROUND: More than 50% of patients with major depressive episode (MDE) fail to respond to initial treatment with first line pharmacological therapy. Altered receptor and serotonin transporter function are considered to be associated with mental disorders. Our investigation aimed on the density of the HT1A receptor in mesiotemporal cortex (MTC) and raphe measured by F18-Mefway in patients with MDD. METHODS: Patients with untreated clinically suspected major depressive episode were recruited from June 2012 to May 2014. 49 patients were included into the study: 36 patients (73%) were identified as responders, whereas 13 (27%) were non-responders. Gender distribution was 26 men (56%) and 23 women (44%). For treatment, only a standard medication of a selective serotonin reuptake inhibitor (SSRI) with escitalopram in a range of 10-20 mg/day was permitted. Responders were defined by improvement of the MADRS>50%. Visually MTC had the highest uptake of F18-Mefway among all brain regions, an asymmetry could not be observed in any patient. An elliptical region was drawn over the amygdala and hippocampus area and a small circular region was drawn over the raphe nuclei. All data were calculated related to (unspecific) cerebellar uptake. RESULTS: The quotient of the right MTC was 5.00 [4.33; 5.50] in all patients, in responders 5.00 [4.00; 5.75] and in non-responders 5.00 [4.50; 5.50] (P=0.56). The quotient of the left MTC presented with a median level of 4.50 [4.50; 5.50] in all persons. The responders had 4.50 [4.50; 5.75] which was not statistically significant to the data of the non-responders with 5.00 [4.50; 5.50] at P=0.64. The raphe had a median quotient of 2.50 [2.00; 3.00] in all and the cohort of responders, whereas non-responders had 2.50 [2.00; 2.50] (P=0.61). Also the absolute values of SUV in the three brain regions were not statistically different between the cohorts. Additionally, we did not find any sex-related differences in our patient group. CONCLUSIONS: Serotonin 1A receptor density can be assessed efficiently by F18-Mefway and PET-CT in patients with MDE. The method can be estimated as a possible tool for clinical and academic investigation, marked tracer uptake can constantly be observed at MTC and the raphe. Anyhow, under conditions of real life in patient care, it is not possible to distinguish patients with a good prognosis who will respond to standard SSRI therapy from non-responders who would benefit from a different therapeutic approach starting earlier.

68Ga/64Cu PSMA Bio-Distribution in Prostate Cancer Patients: Potential Pitfalls for Different Tracers.

BACKGROUND: 68Ga-PSMA is a widely useful PET/CT tracer for prostate cancer imaging. Being a transmembrane protein acting as a glutamate carboxypeptidase enzyme, PSMA is highly expressed in prostate cancer cells. PSMA can also be labeled with 64Cu, offering a longer half-life and different resolution imaging. Several studies documented bio-distribution and pitfalls of 68Ga-PSMA as well as of 64Cu- PSMA. No data are reported on differences between these two variants of PSMA. Our aim was to evaluate physiological distribution of these two tracers and to analyze false positive cases. METHODS: We examined tracer bio-distribution in prostate cancer patients with negative 68Ga-PSMA PET/CT (n=20) and negative 64Ga-PSMA PET/CT (n=10). A diagnostic pitfall for each tracer was documented. RESULT: Bio-distribution of both tracers was similar, with some differences due to renal excretion of 68Ga- PSMA and biliary excretion of 64Cu-PSMA. 68Ga-PSMA uptake was observed in sarcoidosis while 64Cu- PSMA uptake was recorded in pneumonitis. DISCUSSION: Both tracers may present similar bio-distribution in the human body, with similar uptake in exocrine glands and high intestinal uptake. Similarly to other tracers, false positive cases cannot be excluded in clinical practice. CONCLUSION: The knowledge of difference in bio-distribution between two tracers may help in interpretation of PET data. Diagnostic pitfalls can be documented, due to the possibility of PSMA uptake in inflammation. Our results are preliminary to future studies comparing diagnostic accuracies of 68Ga-PSMA and 64Cu-PSMA.

Uptake of 68Ga-Prostate-Specific Membrane Antigen PET in Adrenal Gland: A Potential Pitfall.

A 76-year-old man with prostate cancer pT2c N0 M0 R1 GS9 (4+5) operated 2009 and radiated postoperatively underwent restaging by Ga-PSMA-PET in January 2017 because of PSA rise at 0.44 ng/ml under medication with GnRH analogues. An intense focal uptake of the diffusely enlarged left adrenal gland was observed as the only pathological finding. Further evaluation by MRI imaging revealed a plump left adrenal gland with a relatively enlarged diameter of 2 cm and excluded tumor and nodular hyperplasia as well. Without any change of the therapeutic regime the patient presented in July 2017 with a PSA level of 0.05 ng/ml and no sign of cancer progress.

Is there a place for FET PET in the initial evaluation of brain lesions with unknown significance?

PURPOSE: The aim of this study was to evaluate the clinical value of the use of O-(2-[(18)F]fluoroethyl)-L: -tyrosine (FET) positron emission tomography (PET)/computed tomography (CT) in patients of a neurological clinic for evaluation of brain lesions newly diagnosed by magnetic resonance imaging (MRI). METHODS: We evaluated 88 patients (44 women and 44 men) with a mean age of 50 +/- 19 years who were sent consecutively for evaluation of an intracerebral mass or lesion observed by MRI from 2006 to 2008. Hospitalization was necessary due to neurological clinical symptoms. Images were obtained by PET/CT 30 min after i.v. injection of 185 MBq FET. Coregistration with MRI was done by HERMES workstation. RESULTS: FET uptake above the cortical level was observed in 60 patients. Neurosurgery was performed in 60 patients (51 with FET-positive imaging); 36 high-grade and 19 low-grade tumours were verified histologically. The sensitivity of FET PET for high-grade tumours (WHO III-IV) was 94% in this setting. Among the low-grade brain tumours (WHO I-II) 13 of 19 were FET positive, which indicates a sensitivity of 68%. Five of ten (50%) astrocytomas I and II could not be visualized by FET. Histological data were not provided for 28 of 88 patients, so the diagnostic approach is based upon longitudinal observation. Radiological and/or clinical control was done at a median of 7 months later. Three patients (all FET positive) died a few months after the examination because of rapid progression of the malignant brain tumour. A malignant entity could be excluded in the other 25 patients. Considering the whole cohort of 88 patients, 43 patients with malignant tumour could be identified, including high-grade glioma, intracerebral lymphoma (n = 1) and metastasis (n = 3). The sensitivity of FET PET for detecting a malignant tumour entity was 93%. We observed two false-positive cases with postischaemic lesions. Remarkably, the two patients with cerebral gliomatosis were false-negative on FET PET imaging. The negative predictive value for a malignant entity was calculated to be 89%. CONCLUSION: Our results indicate a high sensitivity of FET PET for detecting high-grade glioma in patients with neurological symptoms and recently observed brain lesions by MRI. In the setting of evaluating new brain lesions of unknown significance via FET PET a negative image can encourage a wait and see strategy-of course in accordance with the clinical picture and morphological imaging.

99mTc-apcitide scintigraphy in patients with clinically suspected deep venous thrombosis and pulmonary embolism.

AIM: Detection of acute deep venous thrombosis (DVT) in patients presenting with clinical symptoms suggesting DVT and pulmonary embolism (PE) with (99m)Tc-apcitide, a synthetic polypeptide, binding to glycoprotein IIb/IIIa receptors expressed on activated platelets is the objective of the study. MATERIALS AND METHODS: Nineteen patients (11 males, eight females) received within 24h after admission to the hospital a mean of 841 MBq (range 667 to 1,080) (99m)Tc-apcitide i.v. followed by planar recordings 10, 60, and 120 min after injection. Images were compared to the results of compression ultrasonography and/or phlebography. Patients with clinically suspected PE underwent spiral computed tomography or lung perfusion scans. RESULTS: (99m)Tc-apcitide scintigraphy showed acute clot formation in 14 out of 16 patients where the other imaging modalities suggested DVT. Positive scintigraphic results were seen up to 17 days after the onset of clinical symptoms. In three out of three patients without any proof of DVT, (99m)Tc-apcitide scintigraphy was truly negative. Glycoprotein receptor imaging showed only one segmental PE in six patients with imaging-proven subsegmental (N = 3) or segmental PE (N = 3). CONCLUSION: (99m)Tc-apcitide scintigraphy may be an easy and promising tool for the detection of acute clot formation in patients with DVT up to 17 days after the onset of clinical symptoms with a sensitivity of 87% and a specificity of 100%. However, it failed to demonstrate PE in 83% of examined patients with proven PE.