[en] Short communication

[en] Solitary fibrous tumor is rare mesenchymal tumor affecting mainly the pleura, the visceral pleura is the most commonly affected. It is usually a benign tumor but may have an unpredictable behavior and a malignant potential, complete excision is the standard of treatment. We present a case of solitary fibrous tumor of the mediastinal pleura which is a very rare incidence. Also, we reviewed the literature related to the condition. (authors).

[en] The multiple physical factors inherent to the acquisition process of the positron emission tomography imply possible levels of imprecision in the image acquisition process, which can translate into an incorrect description of the patient's pathology. It is necessary to know, analyze and apply a quality assurance plan that includes the performance of the positron emission tomograph with respect to the initial acceptance and/or factory results, to measure its level of reliability and thus way to ensure the quality of the medical diagnosis that is made to patients who require this aid. The impact of the performance parameters of the tomograph was evaluated, regarding its significance in the quality of the medical diagnosis. The PET sensitivity was determined using a linear source of 18F-FDG with 4.44 MBq (0.12 mCi); the sensitivity was obtained at 0 cm from the FOV axis: 6.28 cps/kBq, and at 10 cm from the FOV axis: 5.96 cps/kBq. The PET resolution was calculated by means of the sum of the FWHM of the PSF functions in each one of the acquisition positions of a source of 3.30 MBq (89.15 ?Ci) contained in a volume of 1.9 mm³. The dispersion fraction, random-total radius and NECR were determined by means of a 71.0 +- 0.1 cm long linear source, with an activity of 1070 MBq (28.92 mCi), obtaining 35.5% for the scatter fraction parameter, and a NECR peak equal to 103.31 kcps. The evaluation of image quality was carried out using the usual acquisition protocol of the service. The percentage of contrast observed in the hot spheres was greater than 60% and in the cold spheres it was greater than 75%. The accuracy of attenuation correction and correction of scattered events was observed with percentages of 15.36% and 8.52% for the image plane closest to the scattering phantom. The performance evaluation of the PET component in the Biograph mCT tomograph, through the NEMA tests, allowed to conclude an optimum operating condition.

[en] Preoperative detection of extranodal spread (ENS) in head and neck cancer can have important consequences for patient management. The aim of this study was to determine whether 18-fluorodeoxyglucose positron emission tomography ([18F]FDG PET) or a combination with Magnetic Resonance Imaging (MRI) could more accurately predict ENS, especially with the near availability of fully integrated [18F]FDG PET/MRI scanners. In retrospective cohort design a total of twelve patients, with 18 lymphnode metastases were studied with [18F]FDG PET and MRI. Presence of ENS was scored on MRI, and [18F]FDG PET images using a SUV max cut-off point of 12. Histopathology results were used as reference standard. Sensitivity, specificity and accuracy were calculated. The sensitivity, specificity and accuracy of [18F]FDG PET for ENS reached 70%,100% and 83%, respectively. The mean SUVmax of ENS positive lymphnodes was 13.6 versus 8.7 for lymphnode metastases without ENS (P=0.03). The sensitivity, specificity and accuracy of MRI for ENS were 70%, 100% and 83%, respectively. When the [18F]FDG PET and MRI findings were combined sensitivity, specificity and accuracy were 80%, 100% and 89%, respectively. Thus, accuracy increased from 83% to 89%. When there is no ENS or doubt of ENS on MRI, [18F]FDG PET seems to have additional value since it improves sensitivity and resolves uncertainty in case of high FDG uptake. This benefit needs to be confirmed prospectively in a larger cohort.

[en] Statistical iterative reconstruction is now widely used in clinical practice and has contributed to significant improvement in image quality in recent years. Although primarily used for reconstruction in emission tomography (both single photon emission computed tomography (SPECT) and positron emission tomography (PET)) there is increasing interest in also applying similar algorithms to x-ray computed tomography (CT). There is increasing complexity in the factors that are included in the reconstruction, a demonstration of the versatility of the approach. Research continues with exploration of methods for further improving reconstruction quality with effective correction for various sources of artefact

[en] The National Cancer Institute (NCI) is currently building a positron emission tomography facility that will house a cyclotron and a PET fusion scanner. lt should be operational as of december 2007, being a cancer dedicated national referral center, the NCI should provide both positron-emitting radiopharmaceuticals and medical services to institutions and patients nationwide. PET technology provides metabolic information that has been documented to be useful in patient care. The properties of positron decay allow accurate imaging of the in vivo distribution of positron-emitting radiopharmaceuticals. a wide array of positron-emitting radiopharmaceuticals has been used to characterize multiple physiologic and pathologic states. The major clinical PET applications are in cancer patients using fluorine-18 fluorodeoxyglucose (FDG). FDG, an analogue of glucose, accumulates in most tumors in a greater amount than it does in normal tissue. PET is being used in diagnosis and follow-up of several malignancies, and the list of articles supporting its use continues to grow. in this article, the instrumentation aspects of PET are described and most of the clinical applications in oncology are described

[en] Positron emission tomography (PET) is a medical imaging technique that measures the three-dimensional distribution of molecules marked by a positron-emitting particle. PET has grown significantly in clinical fields, particularly in oncology for diagnosis and therapeutic follow purposes. The technical evolutions of this technique are fast. Among the technical improvements, is the coupling of the PET scan with computed tomography (CT). PET is obtained by intravenous injection of a radioactive tracer. The marker is usually fluorine (¹⁸F) embedded in a glucose molecule forming the 18-fluorodeoxyglucose (FDG-18). This tracer, similar to glucose, binds to tissues that consume large quantities of the sugar such cancerous tissue, cardiac muscle or brain. Detection using scintillation crystals (BGO, LSO, LYSO) suitable for high energy (511keV) recognizes the lines of the gamma photons originating from the annihilation of a positron with an electron. The electronics of detection or coincidence circuit is based on two criteria: a time window, of about 6 to 15 ns, and an energy window. This system measures the true coincidences that correspond to the detection of two photons of 511 kV from the same annihilation. Most PET devices are constituted by a series of elementary detectors distributed annularly around the patient. Each detector comprises a scintillation crystal matrix coupled to a finite number (4 or 6) of photomultipliers. The electronic circuit, or the coincidence circuit, determines the projection point of annihilation by means of two elementary detectors. The processing of such information must be extremely fast, considering the count rates encountered in practice. The information measured by the coincidence circuit is then positioned in a matrix or sinogram, which contains a set of elements of a projection section of the object. Images are obtained by tomographic reconstruction by powerful computer stations equipped with a software tools allowing the analysis and quantification of images. PET technology has undergone further evolutions the last few years; the most important is the technique of time of flight [TOF] that was introduced in 2005 in clinical routine. The flight time is a measure of the difference in arrival times of the two photons detected in coincidence. This is possible only with scintillation crystals having a scintillation short decay time (40 ns) like the LSO or LYSO. The flight time allows to increase the signal / noise ratio and to better visualize small lesions while reducing time acquisition and/or radiation dosimetry. CT allows a precise anatomical location of metabolic lesions visible on PET and an attenuation correction of SPECT slices by images fusion. PET has become a recommended exam in accordance with SOR (Standards, Options and Recommendations) on a large number of cancers for positive and differential diagnosis, therapeutic evaluation and monitoring. If this technique is deemed to have lower spatial resolution than morphological imaging techniques, it has the advantage of having the highest detection sensitivity. Coupling PET-CT can overcome this challenge. (Author)

[en] Tomography is used to image anatomy of organs as in the case of CT and MRI or image body functions as in the case of SPECT and PET. The theory of reconstruction applies equally well to CT, SPECT and PET with a minor differences. The main difference between SPECT and PET is that SPECT images single photon emitters (radionuclides) which emit normal gamma rays (like Tc-99m), whereas PET images positron emitting radionuclides such as O¹⁵ or F¹⁸. The word tomography means drawing of the body. Every tomography results in an image of the inside of the body and is represented as a slice. (author)

[en] The aim of this study was to report on the feasibility and accuracy of spleen volume determination on FDG PET/CT imaging using region growing and the CT part of the PET/CT examination as anatomical landmark (PET-CT based spleen volume method PBM) and volume summation of axial CT sections of the spleen as gold standard (true spleen volume (TSV). We also aimed to compare results obtained to the estimative methods (ESV). Thirty-nine FDG PET/CT images taken from 32 patients (15 women, age range: 16-83 years) suffering from lymphoma, covering a wide range of spleen volumes based on visual CT assessment, in whom CT as well as FDG PET images revealed no focal spleen abnormalities were included for analysis. ESV1, ESV2 and PBM were determined on all examinations and compared to TSV. ESV1 volumes were significantly larger (median 668 cm"3 [range: 121-4303 cm"3] [P=0.0001]) and ESV2 volumes significantly smaller (median 424 cm"3 [range: 84-2679 cm"3] [P=0.0001]) when compared to TSV volumes (median 582 cm3 [range: 105-4847 cm"3] which was not so for PBS volumes (median 540cm"3 [range: 120-4560 cm3]). Time needed for TSV assessment (median: 17 min. [range: 6-65 min.]) was related to spleen volume (r=0.691 [P=0.0001]). The mean and standard deviation of the percentage spread (ESV1, ESV2, PBM-TSV/100%) around the mean (ESV1, ESV2, PBM+TSV/2) were respectively 18%±15.6% (ESV1 vs. TSV), -25%±15.6% (ESV2 vs. TSV) and -2.8%±12.3% (PBM vs. TSV). Mean SUVmax of the spleen was 4.8 SUV (SD: 2.6 SUV), mean percentage cut-off for region growing was 7.3% (sd: 5.8%). Spleen volumes defined by PBM correlated with their corresponding SUVmax value (r=0.469 [P=0.03]). Time needed for PBM measurements was between 2-3 min in all patients. Spleen volumes may be rapidly and accurately derived from the FDG PET part of the PET/CT examination through region growing and by using the CT part of the PET/CT examination as anatomical landmark for contour delineation. As opposed to ESV1 and ESV2, the PBM method does not suffer from a systematic bias and shows a smaller variation against the mean percentage difference. Combining functional and morphological data for spleen volume assessment is time-saving.

[en] Purpose: The effectivenes of maintenance treatment with PARP inhibitor olaparib in platinum-sensitive recurrent serous, papillary, high-grade carcinoma of the left adnexais presented. Case report: We describe the case report of a cacer patient who was 43 year sold at thetime of diagnosis. After 36 months, a platinumsensitive relapse of a serous, papillary, high-grade tumor of left adnexawas confirmed. The patient was treated with 2-line palliative chemotherapy paclitaxel, carboplatina (7 cycles) and subsequently treated with maintenance treatmet with olaparib untilnow. The basic diseaseis in complete remission. Conclusion: Olaparib is the first PARP inhibitorisindicated as maintenance therapy in patients with BRCA mutations, with newly diagnosed advanced ovarian cancer and also in patients with platinum-sensitive recurrent ovarian cancer who have achieved a terapeutic response to platinm-based chemotherapy. (author)