Eva Ferdová

Fever of unknown origin: A value of 18F-FDG-PET/CT with integrated full diagnostic isotropic CT imaging

AIM The aim of presented work is to evaluate the clinical value of (18)F-FDG-PET/CT in patients with fever of unknown origin (FUO) and to compare PET/CT finding with the results of the following investigation. MATERIAL AND METHOD 48 patients (24 men, 24 women, mean age 57.6 years with range 15-89 years) underwent (18)F-FDG-PET/CT due to the fever of unknown origin. All examinations were performed using complex PET/CT protocol combined PET and whole diagnostic contrast enhanced CT with sub-millimeter spatial resolution (except patient with history of iodine hypersensitivity or sever renal impairment). CT data contained diagnostic images reconstructed with soft tissue and high-resolution algorithm. PET/CT finding were compared with results of biopsies, immunology, microbiology or autopsy. RESULTS The cause of FUO was explained according to the PET/CT findings and followed investigations in 44 of 48 cases-18 cases of microbial infections, nine cases of autoimmune inflammations, four cases of non-infectious granulomatous diseases, eight cases of malignancies and five cases of proved immunity disorders were found. In 46 cases, the PET/CT interpretation was correct. Only in one case, the cause was overlooked and the uptake in atherosclerotic changes of arteries was misinterpreted as vasculitis in the other. The reached sensitivity was 97% (43/44), and specificity 75% (3/4) respectively. CONCLUSION In patients with fever of unknown origin, (18)F-FDG-PET/CT might enable the detection of its cause.

Pulmonary imaging using dual-energy CT, a role of the assessment of iodine and air distribution.

AIM The aim of the study is to present the feasibility of using dual-energy CT and the evaluation of iodine and air distribution in differentiation of pathological conditions. MATERIAL AND METHOD We used the data of 50 CT examinations performed due to suspected pulmonary embolism with any pathological finding except consolidation of the parenchyma. The patients underwent CT angiography of the pulmonary arteries on a dual-source CT (DSCT), with the two tubes independently operated at 140 and 80 kV. By exploiting the dual-energy information, iodine distribution maps were obtained in addition to the conventional CT images which served as a marker of pulmonary perfusion. Minimum intensity projections (MinIP) were used as a marker of air content. RESULTS By comparing the iodine distribution maps and MinIP images, it was possible to differentiate between the following templates of lung parenchyma: A--normal iodine and air distribution; B--iodine content deficit with minimal or with no redistribution of air; C--reduced iodine content and increased content of air; D--deficit of iodine content and increased content of air; E--increased iodine content and normal content of air; F--increased iodine content and reduced content of air; G--reduced perfusion and reduced content of air. The type A (five cases) was typical for the pulmonary embolism with preserved normal conditions of perfusion and ventilation. Type B (18 cases) occurred in pulmonary embolism; type C was found in case of inflammation of small respiratory airways (five cases); emphysema was typical for type D (nine cases); increased perfusion was observed in the parenchyma preserved from emphysema or preserved from embolism in cases of emphysema or pulmonary embolism; type F occurred in pulmonary interstitial edema (four cases) both with pulmonary infection; finally type G was found in interstitial lung diseases (five cases). CONCLUSION Imaging of the pulmonary circulation by means of dual-energy CT opens the potential to study pathological changes of circulatory and pulmonary perfusion impairments, our presented work signs the important relations between iodine and air distribution which have to be thought in the interpretation of dual-energy perfusion imaging of the lungs.

Diffusion tensor magnetic resonance imaging of glial brain tumors

AIM To evaluate the authors experience with the use of diffusion tensor magnetic resonance imaging (DTI) on patients with glial tumors. METHODS A retrospective evaluation of a group of 24 patients with glial tumors was performed. There were eight patients with Grade II, eight patients with Grade III and eight patients with Grade IV tumors with a histologically proven diagnosis. All the patients underwent routine imaging including T2 weighted images, multidirectional diffusion weighted imaging (measured in 60 non-collinear directions) and T1 weighted non-enhanced and contrast enhanced images. The imaging sequence and evaluation software were produced by Massachusetts General Hospital Corporation (Boston, MA, USA). Fractional anisotropy (FA) maps were calculated in all patients. The white matter FA changes were assessed within the tumorous tissue, on the tumorous borderline and in the normally appearing white matter adjacent to the tumor. A three-dimensional model of the white matter tract was created to demonstrate the space relationship of the tumor and the capsula interna or corpus callosum in each case using the following fiber tracing parameters: FA step 0.25 and a tensor declination angle of 45 gr. An additional assessment of the tumorous tissue enhancement was performed. RESULTS A uniform homogenous structure with sharp demargination of the Grade II tumors and the wide rim of the intermedial FA in all Grade III tumors respectively, were found during the evaluation of the FA maps. In Grade IV tumors a variable demargination was noted on the FA maps. The sensitivity and specificity for the discrimination of low- and high-grade glial tumors using FA maps was revealed to be 81% and 87% respectively. If the evaluation of the contrast enhancement was combined with the evaluation of the FA maps, both sensitivity and specificity were 100%. CONCLUSION Although the evaluation of the fractional anisotropy maps is not sufficient for glioma grading, the combination of the contrast enhancement pattern and fractional anisotropy maps evaluation improves the possibility of distinguishing low- and high-grade glial tumors. Three-dimensional models of the white matter fibers in the corpus callosum and the internal capsule may be used in the presurgical planning.

18F-FDG-PET/CT of orofacial tumors, a value of whole-body imaging approach

AIM Staging of head and neck tumors is one of the most difficult tasks in imaging techniques, due to the very complicated head and neck anatomy and serious problems with the differentiation of reactive enlarged lymph nodes and lymph nodes involved with metastases. The aim of the study was to evaluate the validity of the whole-body approach in the assessment of head and neck malignancies using (18)F-FDG-PET/CT. MATERIALS AND METHODS The analysis of a group of 1750 consecutive whole-body procedures in all indications of (18)F-FDG-PET/CT was made according to: the presence of orofacial tumors; their histology; findings concerning the spread outside head and neck region; and findings concerning the primary staging or restaging. The examinations of head and neck tumors were performed after intravenous application of the (18)F-FDG and its accumulation for one hour. Drinking and speaking is restricted during this accumulation to prevent artificial muscle (18)F-FDG uptake and to minimize false positive findings. In our hospital, high resolution PET is followed by the sub-millimeter isotropic acquisition of CT data after intravenous application of an iodinated contrast material. The acquisitions of head and neck region and trunk are performed separately to obtain optimal resolution in both regions. RESULTS 105 examinations of the orofacial tumors were performed on 87 patients in a group of 1750 consecutive PET/CT examinations. The ratio between primary staging and restaging was 3:7. The most frequent indications were carcinomas of the tongue (19 examinations) and carcinomas of the salivary glands (19 examinations). The metastatic spread of the tumor outside the region of the head and neck was noted in 12 cases. CONCLUSION Our findings of distant metastases confirmed the importance of the use of whole-body PET/CT in this indication.

18F-FDG-PET/MRI in lymphoma patients

The introduction of hybrid PET/MRI imaging using integrated systems into clinical practice has opened up the possibility of reducing the radiation dose from hybrid imaging by eliminating the contribution from computed tomography. Studies comparing the possibilities of PET/CT and PET/MRI imaging demonstrated it is possible to use the advantages of the high contrast resolution of magnetic resonance for soft tissue and bone marrow along with PET records in a quality comparable to PET/CT imaging. The significant feature for PET imaging in Hodgkińs lymphoma is that it is a tissue with high levels of radiopharmaceutical accumulation, which decreases proportionally after successful therapeutic effect, the effect of therapy is assessed using Deauville score system on interim examinations. While the efficacy of prognosis determined using the Deauville scale in HL is widely accepted, it turns out that in DLBCL, the prognostic value of PET imaging is bound to the evaluation of subtypes. PET/MRI scanning can be used to evaluate a relapse if follicular lymphoma has already been treated, or to confirm transformation into more aggressive forms. In children and adults with Burkitts lymphoma, negative findings after induction therapy have a high negative predictive value for relapse prognosis.

Pancreatic undifferentiated carcinoma with osteoclast-like giant cells masquerading as (extra)gastrointestinal stromal tumor: Potential diagnostic pitfall

To the Editor: Pancreatic undifferentiated carcinoma with osteoclast-like giant cells (UCWOLGC) is a rare neoplasm comprising <1% of all exocrine pancreatic tumors. Histologically, it is mainly composed of plump spindle-shaped to epithelioid tumor cells and scattered non-neoplastic osteoclast-like giant cells. In addition, an in situ or invasive adenocarcinomatous component may usually be found in some parts of the neoplasm. According to the literature, malignant fibrous histiocytoma, metastatic malignant melanoma, hepatocellular carcinoma, pleomorphic rhabdomyosarcoma, pleomorphic liposarcoma, choriocarcinoma, and extraskeletal (or metastatic) giant cell tumor (of bone) should be considered in the differential diagnosis of UCWOLGC. With the exception of the giant cell tumor, however, all other neoplasms listed here may instead

Low-dose High-resolution18F-FDG-PET/CT Using Time-of-flight and Point-spread Function Reconstructions: A Role in the Detection of Breast Carcinoma Axillary Lymph Node Metastases

Aim: to evaluate the performance of N-staging assessment in clinically-proven T1 breast carcinoma by high-resolution 18F-fluorodeoxyglucose-positron-emission tomography/computed tomography (18F-FDG-PET/CT) using time-of-flight with point-spread function reconstruction. Patients and Methods: In 30 women with clinically proven T1 breast carcinoma, imaging before surgery was performed using 18F-FDG-PET/CT. The results of PET/CT in detection of lymph node metastases were compared with those obtained after pathological investigation of axillary biopsy. A four-ring PET subsystem with image reconstruction using time-of-flight and point-spread function was used with the radiopharmaceutical dose reduction to 2.5 MBq/kg. Results: Axillary lymph node metastasis was confirmed by histology in 13 patients, but metastasis was suspected based on PET/CT in 12 of those patients, the absence of metastasis was surgically confirmed in 17 women, 15 of which were suspected based on PET/CT. The sensitivity for detection of axillary lymph node metastasis was 93.3%, with a specificity of 88.2% in the whole patient cohort. Additionally, distant metastatic spread was found in 13.3% of patients. Conclusion: The reconstruction of PET images with time-of-flight and point-spread function enabled the improvement of diagnostic performance in N-staging of breast carcinoma, even when the dose of radiopharmaceutical was reduced to 2.5 MBq/kg

Hybrid Imaging PET/CT with Application of18F-Fluorothymidine in Patients with Head and Neck Carcinoma Undergoing Radiotherapy

Aim: To introduce the possible benefits of the positron-emission tomography (PET)/computed tomography (CT) with 18F-3’-deoxy-3’-fluorothymidine (18F-FLT) in patients with orofacial carcinomas and its impact to patient management. Materials and Methods: Thirty-six patients with orofacial squamous cell carcinomas underwent 18F-FLT-PET/CT during radiotherapy. Examinations were performed after administration of 18F-FLT (1.8 MBq/kg) including full-diagnostic CT. Analysis of the radiotherapy effect was performed with possible prospect of repeated and focused irradiation. Results: Complete absence of 18F-FLT uptake was found in 20 patients, thus complete response to radiotherapy was reported. Persistence of focal 18F-FLT uptake was observed in 16 patients; in 11 patients, the measured activity was only mild. In five patients, a higher level of 18F-FLT uptake was measured and additional irradiation was performed in defined regions. Repeated follow-up proved complete regression 18F-FLT uptake. Conclusion: It was possible to assess the effect of radiotherapy with the use of 18F-FLT-PET/CT and findings are suitable for radiation dose-escalation planning.

18F-Fluorocholine PET/MRI in Restaging of Prostatic Carcinoma in Relation to PSA Level and Detection of Active Disease

Aim: To evaluate our own experience with 18F- fluoromethylcholine-(FCH)-positron-emission tomography combined with magnetic resonance imaging (PET/MRI) in restaging of patients with prostatic carcinoma and elevated serum prostate-specific antigen (PSA) level. Patients and Methods: The analysis was performed on a sample of 100 male patients who underwent 18F-FCH-PET/MRI, with a mean age of 63.2 years (range=47-78 years). The imaging was performed using an integrated PET/MRI hybrid system after intravenous application of 18F-FCH at a dose of 1.25 MBq/kg. The number and sites of pathological accumulation of FCH related to local recurrence, nodal spread and skeletal metastases were compared to corresponding MRI findings; furthermore, the relation of PSA level and presence of FCH accumulation in tumorous tissue was assessed; finally we correlated the findings of different sites of metastatic involvement. Results: In patients with a PSA level up to 2 ng/ml, accumulation in tumorous tissue of local recurrence or metastases was found in 83.33% in cases of biochemical relapse, and in patients with PSA level above 5 ng/ml in 100% of cases. In general, we found any finding explained rise of PSA level in 94% of patients. Conclusion: 18F-FCH-PET/MRI using an integrated system with 1,25 MBq/kg dosing of FCH is a valuable tool in evaluation of restaging in patients with prostatic carcinoma, with high detection rate even in those with a low serum PSA level.

PET/MRI of the thorax, abdomen and retroperitoneum: Benefits of the breathing-synchronized scanning

Hybrid imaging using various radiopharmaceuticals is currently essential not only in detection and therapy response monitoring of tumors, but also in assessment of inflammatory or systemic diseases. Combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) is still relatively new method with great prospects of comprehensive assessment using anatomical and multiple functional information. However, benefits of PET/MRI in thorax, abdomen and retroperitoneum are not completely defined. Breathing movements affect imaging of thoracic, abdominal and retroperitoneal organs and pathological structures using PET and MRI. Fast MRI sequences are performed using breath-hold technique; however, acquisition of longer sequences and PET scanning need to be breathing-synchronized. Review article summarizes concrete PET/MRI protocols and importance of concrete MRI sequences and radiopharmaceuticals in different pathological lesions with focus on benefit of breathing-synchronized techniques.