Detection Rate of 18F-Fluorethylcholine-PET/CT in relation to PSA Value in PCA Patients Referred with Biochemical Relapse.

Attempts to predict the likelihood of positive morphological imaging related with PSA value in patients referred with biochemical recurrence were the focus of many studies. Using nuclear medicine modalities, numerous studies likewise had been performed for the same purpose, however mostly using C-11-labeled choline. For this purpose, we selected 193 prostate cancer patients from our database between 2006 and 2010. They had been referred to our department to undergo 18F-fluorethylcholine (FECH)-PET/CT due to biochemical recurrence after potentially curative procedures. As a result, in 84 out of 193 patients, 18F-FECH-PET demonstrated positive findings with an overall detection rate of 44%. Statistically, there was a significant difference in PSA values in positive findings vs. negative findings (p < 0.001), and there was a linear correlation between the detection rate and PSA value (r = 0.91). Moreover, there was a relation between initial therapy and recurrence type. So, the local relapse was the most frequent recurrence (>70%) after radiation therapy alone. By contrast, patients after radical prostatectomy followed by salvage radiotherapy showed a low likelihood of local recurrence. In conclusion, PSA value was confirmed to have a determinant role in 18F-FECH-PET outcome. Moreover, there was a link between recurrence type and initial therapy, which-if prospectively confirmed-may play a guiding role in selecting the appropriate diagnostic methods.

Imaging Comparison between (18) F-FDG-PET/CT and (18) F-Flouroethyl Choline PET/CT in Rare Case of Thymus Carcinoma Exhibiting a Positive Choline Uptake.

It is of great value by using PET imaging in oncology to recognize any atypical uptake not related to the underlying disease. That helps in avoiding the false positive finding and may contribute in extending the application range of used radiopharmaceuticals in further disorders. It is well known that radiolabeled choline is an essential PET tracer used currently in prostate cancer. The physiological choline distribution was described. Nevertheless there is still a lack of studies, which describe this distribution in young patients; given that the radiolabeled choline is generally being used in the field of prostate cancer. Whether the thymus exhibits normally a positive choline uptake or not is still unknown. In particular, it is known that the lymphocytes express high affinity of choline transporter and enzymes involving its metabolism. Some cases of thymus carcinoma exhibiting a positive choline had been reported in the literature, however, mostly using (11)C-choline. We report a rare case of metastatic thymic carcinoma detected incidentally using (18)F-choline-PET in a 78-year-old male patient referred with elevation of prostate specific antigen. Moreover we present a comparison pattern with (18)F-FDG-PET modality, in which (18)F-choline-PET was turned out to be superior in tumor delineation.

Kinetic Modeling Application to (18)F-fluoroethylcholine Positron Emission Tomography in Patients with Primary and Recurrent Prostate Cancer Using Two-tissue Compartmental Model.

Although (18)F-fludeoxyglucose-positron emission tomography (PET) is the most applied diagnostic method in tumor staging, its role in prostate cancer (PCA) is limited because glucose metabolism tends to be low unless PCA has high Gleason score. Alternatively, choline PET was introduced as a valuable imaging method. Kinetic analysis of PET acquisition has increasingly gained momentum as an investigative tool because it provides a non-invasive approach to obtain kinetic and metabolic data from tissues of interest including transport and metabolism of the administered material. In this regard, we sought to apply it in (18)F-fluoroethylcholine (FECH)-PET/computed tomography (CT) in patients with PCA. 64 patients, the mean age 69 (range: 47-87 years) with primary/recurrent PCA were encompassed. They underwent (18)F-FECH-PET started with a dynamic acquisition using a 20-frame each 30 s over the prostate region and followed at 1 h post-injection by a static whole body imaging. The kinetic evaluation of the data was performed using the software package PMOD (PMOD Technologies Ltd., Zürich, Switzerland). Significant increase in mean values for K1, K3, FD, standardized uptake value (SUV) and global influx in tumor tissue versus normal tissue (P < 0.05). Moderate but significant correlation (r: 0.28, P = 0.023) between SUV and K1. By contrast, no correlation between SUV and K3 (r: -0.08, P = 0.79). In patients with recurrent tumors, there is no significant difference in all kinetic parameters and SUV (P > 0.1) between the different types of recurrences. The kinetic analysis of dynamic FECH-PET provides a novel method in primary PCA diagnosis and could be of potential value in the delineation of tumor focus.

Diagnostic Role of (18)F-FECH-PET/CT Compared with Bone Scan in Evaluating the Prostate Cancer Patients Referring with Biochemical Recurrence.

(18)F-FECH-PET/CT has been proved to be an imaging agent for prostate carcinoma. However, its role in detecting the bone metastases is still blurred owing to the lack of related studies. The purpose of our study was to assess the efficacy of PET with (18)F-ethylcholine in assessing the bone status and to compare the results with that of conventional bone scan findings. For this purpose, we selected 37 patients (mean age 69 ± 7), who had been referred for restaging purposes due to biochemical recurrences and underwent both (18)F-FECH-PET/CT and bone scan in a short interval. Generally 18 patients out 37 patients referred with biochemical relapse were confirmed to have bone involvement. From 18 confirmed bone involvement cases, (18)F-FECH-PET/CT identified correctly the bone involvement in 15 cases with overall sensitivity of 83.3%. On the other hand, bone scan identified 17 out of 18 confirmed cases with overall sensitivity of 94.4%. The lesion-related results show that the sensitivity of each investigation differs with the anatomical regions, and by comparing both results, (18)F-FECH-PET/CT was mostly superior to bone scan; however, without a statistical significance (P > 0.1). In conclusion, no significant gain in sensitivity was achieved using bone scan compared with (18)F-FECH-PET/CT.

Radionuclide detection of multiple soft tissue metastases of osteosarcoma masquerading as bone metastasis.

OBJECTIVE: The aim of this work was to report an unusual case of multiple soft tissue metastases of osteosarcoma detected using bone scan and confirmed by CT scan. CLINICAL PRESENTATION AND INTERVENTION: A 15-year-old patient with a history of osteogenic sarcoma presented with fatigue and loss of appetite in addition to a painless swelling of the distal left lower extremity. Bone scan and chest CT scan were performed for restaging purposes. The bone scan revealed multiple bone metastases and suspected tumor recurrence in the left lower extremity in addition to multiple extraosseous hot spots. The latter findings were assessed as ossified soft tissue metastases after considering the performed CT scan. CONCLUSION: This case showed the double role of bone scan in osteosarcoma in simultaneously assessing the bone status and tumor spread in soft tissue. The benefit of a comparison of bone scan findings with other modalities was also demonstrated.

Incidental detection and monitoring of spontaneous recovery of sarcoidosis via fluorine-18-fluoroethyl-choline positron emission tomography/computed tomography.

We report a case of sarcoidosis detected incidentally by using fluorine-18-fluoroethylcholine- positron emission tomography/computed tomography (¹8F-FECH-PET/CT) in a 72 years old patient with prostate cancer, who had been referred for restaging after relapse indicated prostate specific antigen (PSA). The ¹8F-FECH-PET/CT examination showed a focal increased uptake in the prostate bed suggestive for local recurrence, in addition to multifocal uptake in the mediastinum matching with enlarged hilar and paratracheal lymph nodes. Histopathology revealed sarcoidosis. No treatment was recommended. Two years later the patient was referred again to us because of another recurrent PSA elevation. The second ¹8F-FECH-PET/CT showed again the previously described local recurrence, but did not show the previously described mediastinal findings nor the enlarged hilar and paratracheal lymph nodes, thus, illustrating spontaneous healing of sarcoidosis. In conclusion, this case suggests that ¹8F-FECH PET/CT study can show positive findings in sarcoidosis that were no longer detectable after two years, suggestive of spontaneous recovery.

The Potential Benefit by Application of Kinetic Analysis of PET in the Clinical Oncology.

PET is an appropriate method to display the functional activities in target tissue using many types of traces. The visual assessment of PET images plus the semiquantitative parameter (SUV) are the main diagnostic standards considered in identifying the malignant lesion. However, these standards lack occasionally the proper specificity and/or sensitivity. That emphasizes the importance of considering supplemental diagnostic criteria such as the kinetic parameter. The latter gives the way to image the ongoing metabolic processes within the target tissue as well as to identify the alterations occurring at the microscale level before they become observable in the conventional PET-imaging. The importance of kinetic analysis of PET imaging has increased with newly developed PET devices that offer images of good quality and high spatial resolution. In this paper, we highlighted the potential contribution of kinetic analysis in improving the diagnostic accuracy in intracranial tumour, lung tumour, liver tumour, colorectal tumour, bone and soft tissue tumours, and prostate cancer. Moreover, we showed that the appropriate therapy monitoring can be best achieved after considering the kinetic parameters. These promising results indicate that the kinetic analysis of PET imaging may become an essential part in preclinical and clinical molecular imaging as well.

Positive somatostatin receptor scintigraphy in accessory spleen mimicking recurrent neuroendocrine tumor.

We report the case of a female patient who had a neuroendocrine tumor in the pancreatic tail. Followup using (68)Ga DOTA-d-Phe(1)-Tyr(3)-octreotide (DOTATOC) positron-emission tomography (PET)/computed tomography (CT) detected a round, well-circumscribed nodular mass that exhibited positive somatostatin receptors. This finding was highly suggestive of an accessory spleen; however, due to the slight elevation of the tumor marker, recurrence of the tumor or lymph node metastasis of the endocrine tumor was considered as well. Ultimately, splenic scintigraphy (SS) confirmed an accessory spleen. This case shows the benefit of splenic scintigraphy in excluding a recurrent neuroendocrine tumor by confirming an accessory spleen.

Impact of geometric mean imaging in the accurate determination of partial function in MAG3 renal scanning in a patient with retroperitoneal mass.

Liposarcoma frequently occurs in the retroperitoneum and lower extremities, accounting for 20% of all mesenchymal malignancies. Liposarcomas vary by histology and can be classified into four types. Those four types are well differentiated, myxoid/round cell, pleomorphic and dedifferentiated. Due to retroperitoneal location of this tumor, it is expected to affect the kidney position. Renography has provided a unique tool for noninvasive evaluation of various functional parameters e.g. relative renal function. Most renography studies are carried out using the posterior view, under the assumption that the depths of both kidneys are similar so that the radiotracer counts in the region of interest will be attenuated to the same extent. Errors in estimation of the relative renal function may arise if the kidneys are at different depths e.g. secondary to a pushing tumor. Geometric mean imaging from combined anterior and posterior views helps to overcome this issue. This case shows the impact of geometric mean imaging in the truthful determination of partial function in patients with retroperitoneal liposarcoma.