[en] Background: Cardiac positron emission tomography (CPET) has been validated as an imaging procedure for myocardial viability. Various tomographic reconstruction techniques enable us to choose which technique might provide the ‘best’ quality image. ‘Filter back projection’ (FBP) has gained wide acceptance in single photon emission computerized tomography (SPECT) image reconstruction, whilst ‘iterative method’ (ITR) is yet to gain clinical acceptability in CPET. Our objective was to optimize reconstruction parameters (FBP and ITR) using Gaussian filter (GF) and Butterworth filter (BWF) in CPET images and score it for visual perception of image and its diagnostic information content. Methodology: Twenty patients underwent CPET viability study, where first a SPECT imaging was acquired 25 min after injection of 3mCi of Tl20 (thallium chloride) on SPECT gamma camera system (Symbia ‘S’, dual headed; Siemens). This was followed by CPET metabolic imaging after injection of 5mCi 18F-FDG (fluorine-18 fluorodeoxyglucose) on Siemens mCT Biograph. CPET images were processed by FBP using BWF (Group –I), by ITR method using BWF (Group-II), by FBP using GF (Group -III), by ITR using GF (Group-IV), by ITR using BW (Group -V) and by ITR using GF (Group- VI). Four cardiac imaging specialists interpreted processed data of all six groups. For the information content and image quality, scoring was done on a scale of 0-4, with ‘0’ showing inconclusive diagnostic content and ‘4’ showing excellent diagnostic information content. Results: Average score with standard deviations for Group I to VI were 3.5+0.08, 3.68+0.1, 3.58+0.05, 3.68+0.1, 3.58+0.05 and 3.74+0.05, respectively. Scores for diagnostic information content were not significantly different among the groups I to V; however the group VI had an edge over the rest of the groups. Conclusion: ITR method of reconstruction using Gaussian filter may be a better choice for obtaining optimum quality of CPET images. (author)

[en] Background: Breast cancer remains the most prevalent cancer form among women worldwide. Mammography remains the screening modality of choice for breast cancer. About 10 to 15% of cancers are missed by conventional screening imaging tools. High resolution breast PET, known before as positron emission mammography (PEM) is a highresolution molecular imaging technology that has shown great sensitivity and specificity. This modality uses 18F-FDG, a positron-emitting analogue of glucose, to detect metabolic alterations within cells. Also, more specific tracers are used, such as estradiol analogue (18F-FES). 18F-FES may be helpful in identifying patients who will benefit from endocrine therapy (like tamoxifen) and predict the likelihood of response to specific treatment hormonal regimens. Several prototypes and commercial systems have been proposed using very different detector geometries and scintillator crystals. Methodology: The main indication is for patients with diagnosed breast cancer who are best treated by conservative surgery, by defining the surgical margins, and evaluating for multifocal or multicentric disease, even in dense breast, potentially avoiding inadequate treatment, unnecessary or additional surgeries. Occult ductal carcinoma in-situ (DCIS) lesions measuring 2–3 mm in width, not well characterized by any other imaging modality may be revealed. The method is well suited for patients who cannot tolerate or undergo a MRI scanning. 18F-FDG uptake ratio is not affected by hormonal changes, unlike breast MRI. Breast compression is needed to obtain adequate images. It is possible to perform a biopsy in patients at the same time of their high resolution breast PET procedure. False-positive or -negative results: hypermetabolic and inflammatory processes, fibrocystic changes, fat necrosis, some fibroadenomas, post-biopsy changes, lobular carcinomas. High resolution breast PET and MRI have an overall similar accuracy. MRI is limited by specificity. Increased cancer detection was reported when high resolution breast PET and MRI were combined compared to MRI alone. The average effective dose in a high resolution breast PET study is 5 mCi (3.5 mSv). The method can be used when monitoring response to neoadjuvant chemotherapy. High resolution breast PET will be better suited for high-risk screening of positive BRCA patients. Results: The first step is identification of hot spots. Once identified, the size, location, and 18F-FDG uptake of the lesion is obtained. Because of the lack of attenuation correction, a “lesion-to-background” ratio (LTB) for semiquantitative analysis is required. An LTB of > 2.5 is more likely to be malignant. Breast tumours of higher histological grade have significantly higher values than those with lower grade. Final assessment of the lesion is based on both morphology and semiquantitative 18F-FDG uptake considered together with findings of other recent breast imaging procedures. Conclusion: High resolution breast PET is a sensitive and specific tool for the evaluation of suspicious breast lesions. It has a great reliability in detecting DCIS and has the potential to play a major role in improving the diagnosis of breast cancer. High resolution breast PET defines the surgical margins, evaluates multifocal or multicentric disease even in dense breast, potentially avoiding inadequate treatment, unnecessary or additional surgeries. It is useful in differentiating recurrent disease from post-treatment changes and monitoring response to neoadjuvant chemotherapy. (author)

[en] Background: Prostate carcinoma remains a major public health problem in developed countries. Adenocarcinoma of the prostate is the second most common cause of cancer death among men. The occurrence of metastases is one of the major causes of morbidity and mortality in prostate cancer patients. The development of locally advanced and metastatic disease is usually insidious and, for most patients presenting with symptoms, the tumour is all too frequently incurable and treatment remains essentially palliative. The early detection of these metastatic or recurrent lesions is of high clinical relevance for staging, prognosis, and therapy management. The prostate-specific membrane antigen (PSMA) represents a cell surface target suitable for imaging metastatic lesions as it is expressed by nearly all prostate cancer cells with enhanced expression levels in poorly differentiated, metastatic, and hormone-refractory carcinomas. The aim of the study was to evaluate the role of 68-Ga labeled PSMA PET/CT scan in the evaluation of prostate cancer and its correlation with histopathology findings in suspected or diagnosed cases of prostate cancer. Methodology: We studied 200 patients, who were suspected to have prostate cancer based on clinical and biochemical evaluation and patients of prostate cancer proven by histopathology. All the patients were injected with 132-222 MBq (4-6 mCi) of 68Ga-PSMA and PET/CT was acquired from the vertex to the mid-thigh using a dedicated GE Discovery STE PET/CT scanner within 45 ± 15 minutes after injection. A delayed sequence of pelvis was acquired after lasix injection in all patients. Results: 68Ga-PSMA PET/CT scan is a very sensitive technique for detection of primary prostate cancer, small lymph node, bone and liver metastases and cancer relapses, with improved contrast even at low PSA levels due to significantly high radiotracer uptake in the lesion and very low background uptake. Conclusion: Our preliminary results show that 68Ga-PSMA PET/CT scan is a very sensitive and reliable technique in the evaluation of patients with carcinoma prostate. (author)

[en] Background: The objective of the study was to demonstrate if the changes in the maximum standardized uptake values (SUVmax) after 2 cycles of neoadjuvant chemotherapy may predict early response in patients with locally advanced ductal breast carcinoma and differentiate responder from non-responder patients. Methodology: This is an observational, prospective study. Between the years of 2008 and 2013, 32 patients were included with the diagnosis of locally advanced ductal breast carcinoma. All patients underwent 2 whole body 18F-FDG-PET/CT studies utilizing GE Discovery STE 16 equipment, before treatment (baseline PET/CT) and after the second cycle of chemotherapy (interim PET/CT). The 18FFDG uptake of the lesions was quantified using SUVmax and compared between the two PET/CT studies. Subsequently, all patients underwent surgery and the results were correlated with surgical pathology specimen. Results: In 11/32 (34.3%) patients a decrease lower than 50% or no change in the SUVmax were observed, either from the primary lesion or the regional nodes involvement, all of them showing gross residual disease in the surgical specimens and 3 (27.2%) of them also presented distant progression disease in the interim PET/CT. In 18/32 (56.2%) cases the SUVmax decreased more than 50%, showing minimal pathologic residual disease or complete pathologic response differentiating responder from nonresponder patients with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 68%, 86%, 94.4%, and 43%, respectively. The average SUVmax decrease in responders and non-responder patients was 65.2% and 24.7% respectively (p < 0.0005). Also, in 8 of the 18 responder patients (44.4%) the decrease in SUVmax was greater than 80%; 3/8 (37.5%) of these patients presented smaller than 1cm residual tumours in the surgical specimen and 5/8 (62.5%) of them showed pathological complete response, however only one patient had also pathological complete response with a SUVmax decrease of 68.5% (lower than 80% but greater than 50 %). Conclusion: In our study, a decrease in the SUV value equal or more than 50 % after 2 cycles of neoadjuvant chemotherapy had a positive correlation with pathological response and allowed to differentiate responder from the non-responder patients. Furthermore, a decrease in SUVmax value equal or more than 80% showed high correlation with complete pathologic response. (author)

[en] Background: With a population of 22 million people Romania is one of the largest countries in Eastern Europe. Nuclear medicine was introduced as diagnostic and therapeutic technique in Romania in the late 1950s and has evolved as independent specialty in 1992. Introduction of PET-CT in Romania was a difficult process, mainly because of the cost of equipment, lack of medical cyclotrons at the beginning and reimbursement issues. Methodology: In this paper we have reviewed the main steps that were made in Romania with implementing PET-CT in the medical system and in the management of oncologic patients. Data were collected from websites of each PET-CT centre, from the Romanian Society of Nuclear Medicine and from the National Insurance Company website. Results: First PET-CT scanners were installed in the private sector in 2008, in Bucharest and Oradea. The number of procedures and requests increased continuously. The installation of a cyclotron and a unit of 18F-FDG production in a private facility were followed by an increase in PET-CT projects both in private but also in public hospitals. At present there are 5 PET/CT scanners installed in the private sector (2 in Bucharest, 1 in Oradea, 1 in Cluj-Napoca and 1 in Constanta) and 2 in public hospitals (one in Bucharest and one in Craiova). On the other side, this year there are at least 3 more projects where PET-CT scanners are expected to be installed. First cyclotron in public system was installed in Horia Hulubei IFIN Institute in Magurele, near Bucharest, which has developed many projects with the IAEA. At this facility production is expected to start soon, the main advantage being the possibility of obtaining more radiopharmaceutical compounds beyond 18F-FDG. In May 2010 National Insurance Company approved reimbursement of PET-CT procedures for many oncologic indications. Since 2010 there was an increase in number of indications for reimbursement. There was also a continuous increase in the budget and number of investigations approved for reimbursement on an annual basis. At present only oncologic indications are included on the list of procedures. None of the centres is performing other studies such as cardiology or neurology. However there are several projects which include installation of PET-CT scanners in some university-related hospitals where new procedures including cardiology, neurology and inflammation will be introduced. Conclusions: Increased use and widening of PET-CT applications in Romania will require a larger number of nuclear medicine specialists to increase their skills by accessing dedicated courses/trainings. Efforts should be made in this respect, to ensure high quality investigations and improve diagnostic management. (author)

[en] Background: Incidence of neuroendocrine tumors (NET) is increasing due to the development of diagnostic tools including nuclear medicine techniques, conventional and PET imaging. SPECT/CT 99mTc-EDDA/HYNIC-TOC could be available everywhere and have a great potential in the management of NET. The objective of this study was to assess the role of SPECT/CT 99mTc-EDDA/HYNIC-TOC in the management of NET. Methodology: A retrospective study of 110 patients with suspected or confirmed NET was done from 2010 to 2014 in the Department of Nuclear Medicine. Clinical indications were: search of the primary (35%), contribution to the strategy and assessment of therapy (48%), location of the primary site (13%) and search for relapse after surgery (4%). SPECT/CT used was a dual head gamma camera with a diagnostic CT. Double reading of reporting was done systematically for all patients. Results: In the suspected NET, SPECT/CT 99mTc-EDDA/HYNIC-TOC enabled finding the primary in 14/37 (37%) and confirmed the diagnosis in 12 out of 15 patients. All paragangliomas and pancreatic tumors were positive on SPECT/CT 99mTc-EDDA/HYNIC-TOC. For therapy assessment, SPECT/CT 99mTc-EDDA/HYNIC-TOC contributed to the therapeutic strategy in 80% of patients and showed a poor response to targeted therapy in 3 patients. Conclusion: Despite the lack of Gallium peptide PET, SPECT/CT 99mTc-EDDA/HYNIC-TOC was determinant with a great clinical impact in the management of neuroendocrine tumors. (author)

[en] Background: The aim of the study was to evaluate the level of disease after hip arthroplasty using bone scintigraphy and X-ray imaging. Methodology: 62 patients after hip arthroplasty were imaged by a standard method of whole body bone scan. Intestinal uptake was observed visually 3 hours after the intravenous administration of 740 MBq 99mTc MDP. A whole body bone scan; anterior, posterior, oblique spot views of the hip joint region were obtained. The data of bone scan were compared with X-ray imaging. Results: Total number of 62 patients with bone scans and X-ray imaging was statistically evaluated. 38/62 pts (61%) with bone scans had inflammatory processes in the hip joint area that is indicative of instability of the hip joint endoprotesis. However, on Х-ray imaging, inflammation in hip joint was identified in 6/62 pts (9 %) events only. In total there were 62 matching scans and statistical data showed overall good correlation (r = 0.58). Within the group of different matching regions correlation varied: r = 0.51 for head of hip; r = 0.47 for broach of hip; r = 0.56 for cervical of hip. Conclusion: Bone scintigraphy is more sensitive and specific method in determining stabilities s of the hip joint than X-ray imaging in patients with endoprotesis of hip joint. (author)

[en] Background: Lymphatic mapping and radioguided SLN biopsy are accepted standard N-staging procedures in management of breast cancer and malignant melanoma. Currently, a further step forward was made with the introduction of fusion SPECT-CT techniques into this field. Methodology: 61 patients (aged 23-78 years) with breast cancer (T1-T2) and melanoma were included for the period between July 2011 and October 2013. 46 out of all patients had early breast cancer staged as T1-T2a. One patient had metachronic multicentric breast cancer. Another patient had a multifocal tumour with the biggest lesion up to 2cm. 15 out of all patients had melanoma (7F, 8M). Surgical excision of the primary lesion was carried out in all of them. Methods: Peri-areolar or peri-tumoural injections were performed by applying 99mTc-Nanocoll (74 – 110 MBq). Planar images were acquired 30-75 min post injection. Transmission scans using refillable 99mTc plexi-glass source were realized. SPECT-CT with low-dose CT was used (130kV; 30mA). Dynamic study after subdermal application of the tracer around the scar was acquired for 15 min (30sec/frame) followed by planar and SPECT-CT studies in melanoma patients. Tattooing to externally localize the SLN position was accomplished. Radioguided SLN biospy was performed in all patients. Histological examinations were carried out using standard method H&E and/or immunohistochemistry with Cytokeratin AE1/AE3. Results: SLNs were visualized on planar studies in 54 out of 61 patients. Comparing planar lymphoscintigraphy with SPECT-CT, additional “hot nodes” were found which were identified only by fusion images as follows: 7 parasternal nodes, 10 axillary (I-II axillary level) nodes, 3 intramammary nodes (near-by inj. sites), 2 supraclavicular (III axillary level), 1 interpectolal lymph node, 4 iliac and 2 laterocervical lymph nodes and 2 periscapular lymph nodes. One lymph node in the contralateral axilla was visualized in 1 case which was considered as non-SLN. Enlarged non-palpable lymph nodes without tracer uptake were imaged in 3 patients with breast cancer and one with melanoma on the CT part of fusion image. After surgical treatment metastatic involvement of these lymph nodes were proved and patients were up-staged from N0 to N1. Single micrometastases with a size 1x1.5 μm of 2 axillary SLNs were diagnosed by immunohistochemistry in 2 patients with breast cancer, macrometastases in 5 cases. Macrometastases in the SLNs were diagnosed in 6 patients with melanoma. Accurate SPECT-CT mapping of SLNs to identify the lymphatic drainage basin was performed in 4 patients with dorsal melanoma. This information is very useful for radio-guided SLN biopsy. Conclusion: Our results show that SPECT-CT imaging of SLNs increased sensitivity and diagnostic accuracy of lymphoscintigraphy in patients with breast cancer and melanoma by detecting additional “hot” loco-regional nodes and discovering SLNs in cases with negative planar lymphoscintigraphy; by exact localisation of internal mammary SNs; by imaging of interpectoralis LNs; SLN close to the injection site; visualization of “cold” non-palpable enlarged lymph nodes. (author)

[en] Background: The intravenous contrast medium is used for clinical evaluation of the residual disease and also helps in the differential diagnosis of the new lesion, it also clearly identifies the anatomical structure. However, the attenuation correction with post-contrast CT may cause an overestimation of SUV which impacts on the interpretation. The aim of this study is to assess the influence of intravenous contrast medium on clinical and quantitative evaluation in lymphoma patients. Methodology: Twelve lymphoma patients, who underwent whole body PET/CT using intravenous contrast medium, were enrolled into this study. PET images were reconstructed with non-contrast CT and post-contrast CT images under the same reconstructed protocol. The CT attenuation (HU), mean and maximum standardized uptake value (SUVmean and SUVmax) were measured in the same region and same size of ROI at the subclavian vein (ipsilateral to the injected side), descending aorta, liver, spleen and bone marrow. Deauville criteria scoring of each of the two data sets were also recorded. A paired student’s t test was performed to evaluate the significant difference between these two reconstructed PET images. Results: All sixty regions of interest in twelve lymphoma patients revealed statistically significant increase in SUVmean and SUVmax on PET attenuation correction by using post-contrast enhanced CT images, compared to non-contrast images (all P value < 0.02). However, no difference of Deauville criteria scoring was found between these two reconstructed data sets. Conclusion: Although intravenous contrast medium causes significantly increased SUV, there is no impact on Deauville criteria scoring in each patient. Non-contrast CT images for attenuation correction may be skipped to reduce radiation exposure in lymphoma patients. (author)

[en] Background: PET/CT is one of the diagnostic tools with the largest growth worldwide. It has been found to be cost-effective for different use purposes like tumour detection and differential diagnosis of benign and malignant tumours, tumour staging and prognostic stratification, evaluation of response to treatment, restaging and detection of recurrent cancer, radiation treatment planning and development of new anticancer drugs. Methodology: To analyse the feasibility of PET/CT in Costa Rica, taking into account the leading causes of cancer mortality and incidence and also analyse the available human resources. Results: Costa Rica has an approximate population of 4.5 million habitants. Cardiovascular disease and cancer are now leading causes of mortality. In terms of cancer death in women in 2011, the first place corresponds to breast cancer with an adjusted rate of 10.39, followed by stomach with 7.86 and colon with 5.97, which shows a slight increase. Cervical cancer with 4.11 is on the fourth place. Leukemias take the fifth position with 3.73, followed by lung cancer with 3.46. Prostate cancer was first and stomach cancer second with respect to the mortality trend from cancer among men in the period 2000 to 2011. Lung and liver cancer show an upward trend in the last 3 or 4 years. The health system in Costa Rica is based primarily on social security. There are three main hospitals with nuclear medicine departments, none of which have PET/CT already available. However, a project to install a cyclotron in the University of Costa Rica was already launched. The main question is how many PET/CTs should be installed because they represent costly diagnostic tests. There are some studies evidencing a high potential for PET/CT as a cost-effective approach for management of cancer, especially for staging of non-small cell cancer, differential diagnosis of solitary pulmonary nodules, restaging of Hodgkin disease and non-Hodgkin lymphoma, and restaging of colorectal carcinoma. From the point of social security health system, the use of PET in clinical practice seems justified. In the most common malignant tumours in our country, PET/CT has proven to be cost-effective. In terms of human resources, our centres are partially prepared to respond to the needs of referring clinicians. There are three principal hospitals with nuclear medicine departments, and nine nuclear medicine physicians. Each department has at least one nuclear medicine physician with full postgraduate training programme in PET/CT of 3 years in duration as well as some nuclear medicine technologists and radiopharmacists. Conclusion: More training in PET/CT is needed, but we have the right personnel and health system and with the support of organizations like IAEA out goals can be achieved. The cyclotron installation will also enable for selling radiopharmaceuticals to other Central American countries and expanding the use of these technologies in developing countries. (author)