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Objective: The usefulness of stress myocardial perfusion scintigraphy (MPS) for cardiovascular (CV) risk stratification in patients at moderate and high CV risk remains controversial. We tested the hypothesis that different clinical risk profiles influence the test and the likelihood of obtaining a positive coronary angiography (CA) in the following 12 months., Methods: We assessed the prognostic value of MPS in 230 patients classified according to the European Society of Cardiology guidelines., Results: Patients at high and very-high CV risk had a higher prevalence of positive MPS (25.5 vs. 36.7%, P=0.014 and 9.8 vs. 19.5%, P=0.011, respectively), whereas patients at moderate risk had a higher prevalence of negative MPS (45.1 vs. 38.3, P=NS). Multivariate regression analysis showed that positive MPS was an independent predictor of 12-month positive CA only in patients at high CV risk [odds ratio (OR) 8.03, 95% confidence interval (CI) 1.53-42.03, P=0.014] independent of age>60 and coexistence of obesity and previous percutaneous coronary intervention (OR 3.78, 95% CI 1.18-12.78, P=0.032; OR 1.83, 95% CI 1.03-3.26, P=0.039). The C-statistic showed a good discriminatory power of positive MPS in predicting 12-month positive CA (0.68, 95% CI 0.55-0.80, P=0.015). Mantel-Cox analysis showed that after 12 months of follow-up, in patients at high risk, there was a statistically significant difference in the distribution of patients with positive than those without negative CA (log rank P=0.04)., Conclusion: CV risk stratification on the basis of MPS is useful only in patients at high and very-high CV risk. In these groups, MPS can aid stratification for the risk of CV events.

In the last 35 years, many attempts have been made to define criteria for the assessment of treatment response in malignant lymphoma. These systems, with respect to both morphological and molecular imaging, aim to standardize scan results, in order to simplify the interpretation of findings, facilitate multicentric research trials, and compare published data. Unfortunately, there is no consensus among the main international hematological associations on which criteria are the most appropriate. This detailed and comprehensive description of all classifications intends to focus attention on this topic.

Aim: The aim of the study was to assess the prevalence of focal fluorine-18 fluorodeoxyglucose (18F-FDG) activity in the lungs using 18F-FDG PET/computed tomography (CT) without matching CT findings., Materials and Methods: A total of 10,500 consecutive 18F-FDG PET/CT records over 4 years were reviewed for focal incongruence between PET and CT, potentially indicating an artifact 18F-FDG (2.2 MBq/kg) was injected through a butterfly needle, followed by a 10 ml saline flush. Non-contrast-enhanced low-dose CT (140 kV and 40-80 mA) was coregistrated with PET., Results: Sixteen patients (12 men and four women; mean age 63 years, range 44-83) had focal pulmonary areas of high 18F-FDG activity [mean maximum standardized uptake value (SUV max) 15.8; range 3.5-81.0], typically peripheral, with a mean maximum diameter of 1.3 cm (range 0.5-2.2 cm) on PET. 18F-FDG focality was singular in 14 patients, whereas two patients had two foci each. None had corresponding CT abnormalities. Identification of these 'focalities' during the acquisition phase led to late respiratory gated thoracic PET acquisitions in eight patients at 2 h with no significant changes in the location or size of the 'focalities'. Five PET/CTs repeated at 48 h did not confirm the 'focalities'. Five had negative follow-up contrast-enhanced CT. 18F-FDG-positive 'focalities' at PET/CT without anatomical correlation findings were considered as 'artefactual accumulation' of the tracer., Conclusion: In the absence of morphological abnormality, focal pulmonary 18F-FDG activity is very rare (1.5 cases/1000 PET scans) but potentially very 'dangerous'. Artefact identification during acquisition can lead to late respiratory gated images for more confident interpretation, avoiding erroneous reports or further imaging procedures.

Epithelial ovarian carcinoma is a major form of cancer affecting women in the western world. The silent nature of this disease results in late presentation at an advanced stage in many patients. It is therefore important to assess the role of imaging techniques in the management of these patients. This article presents a review of the literature on the role of (18)F-FDG-PET/CT in the different stages of management of epithelial ovarian cancer. Moreover, a comparison with other imaging techniques has been made and the relationship between (18)F-PET/CT and the assay of serum CA-125 levels has been discussed.

Objective: L-6-fluoro 3,4-dihydroxyphenylalanine (18F-DOPA), an amino acid-based radiopharmaceutical, is increasingly being used in the detection and management of neuroendocrine tumours. Knowledge of the normal biodistribution of this radiopharmaceutical is essential for the proper interpretation of such studies, but the literature available is scanty due to the rarity of these tumours. The aim of this study is to evaluate the biodistribution pattern and normal variants of 18F-DOPA in a cohort of patients with neuroendocrine tumours using semiquantitative analysis (maximum standardized uptake value)., Methods: We analysed 107 consecutive 18F-DOPA PET/CT studies of patients referred with medullary carcinoma of the thyroid (43), phaeochromocytoma including cases of Von Hippel Lindau syndrome and multiple endocrine neoplasia type IIA cases (34), paraganglioma (14) and other neuroendocrine tumours (16). The study population were divided into two groups: those with negative 18F-DOPA PET/CT scans (32) and those with positive scans (75). The biodistribution of 18F-DOPA in each group was measured and compared between the two groups., Results: The physiological biodistribution in the basal ganglia and liver parenchyma showed no variability between the two groups. Conversely, uptake in the pancreas (particularly the uncinate process) and adrenals showed considerable variability between the groups. However, these differences were found not to be significant on statistical analysis., Conclusion: The data presented may provide useful information in understanding the physiologic biodistribution of DOPA and its variants, for the purpose of improving the interpretation of 18F-DOPA PET/CT.

Aim: To evaluate clinical efficacy of a dual-time acquisition protocol, which included 4 and 20/24-h imaging with antigranulocyte antibody scintigraphy (LeukoScan) combined with semiquantitative analysis in the diagnosis of infection in painful hip prosthesis., Methods: Sixty-seven consecutive patients with hip prosthesis were enrolled in this research project: 35 females, 32 males, mean age of 56.3 years. All patients had clinical and biochemical suspicious of infection. Each prosthesis had been implanted 3 months to 12 years before enrollment in this study. Twenty-four patients were on antibiotic therapy at the time of scintigraphy. Seven patients had bilateral hip prosthesis, one painful and the other painless: the seven painless prostheses were considered controls. LeukoScan examination was performed both at early (4 h) and delayed (20/24 h) times. The scintigraphic data were assessed both by visual and semiquantitative methods by three experienced nuclear medicine physicians blinded to clinical, laboratory and radiographic results. The uptake was graded visually by a 4-point scale: intense=3, moderate=2, mild=1 and absent=0. The semiquantitative analysis was obtained by a region of interest (ROI) analysis used in the anterior views to measure the ratio between the mean radioactivity in the prosthesis and the background radioactivity in the early and delayed images. An increase in the intensity of uptake of at least one scale-step at visual analysis and 20% at semiquantitative ROI analysis at the dual-time (early vs. delayed) LeukoScan was considered consistent with infection, whereas a stable or decreasing pattern was judged a negative result. Three-phase 99mTc-hydroxymethane diphosphonate bone scan was also performed routinely. Final diagnosis was determined at surgery and/or long-term clinical and imaging follow-up., Results: At visual analysis, sensitivity for both early and delayed imaging was 94%, whereas specificity was 71% for early imaging and 83% for early and delayed imaging approach. At semiquantitative ROI analysis, sensitivity remained 94%, whereas specificity rose slightly to 73% for early imaging and to 90% for early and delayed imaging combined. Of note, four false-positive early scans were diagnosed correctly as negative on delayed imaging showing a decreasing pattern in uptake intensity. Sensitivity and specificity were similar whether patients were on or off antibiotic therapy., Conclusion: Our data show that early imaging LeukoScan is highly sensitive in evaluating septic prosthesis, but it is not optimally specific. Although the dual-time LeukoScan is capable of significantly increasing specificity for detecting infection. The semiquantitative ROI analysis further increased the specificity. Concomitant antibiotic treatment did not seem to influence the diagnostic efficacy of LeukoScan scintigraphy in detecting infected hip prosthesis.

Objective: To evaluate clinical efficacy of a dual-time acquisition protocol consisting of early 4 h and delayed 20-24 h imaging with anti-granulocyte scintigraphy (LeukoScan) in the diagnosis of infection in painful total knee arthroplasty (TKA)., Materials and Methods: Seventy-eight consecutive patients with TKA (12 bilateral) were prospectively enrolled in the study from August 2004 to July 2005. All the patients had clinical and biochemical suspicious of infection, except for the 12 patients with bilateral painless prosthesis who had no signs and symptoms of loosening and/or infection and were considered as controls. TKA prostheses had been implanted 4 months to 9.5 years before our studies. Forty-three patients were on antibiotic therapy at the moment of scintigraphic examination, and treatment was not discontinued. All patients underwent LeukoScan examination by performing both early 4 h and delayed 20-24 h imaging. In addition to planar imaging SPECT was performed in 18 cases. A decrease in radiotracer uptake from early to delayed LeukoScan imaging was interpreted as an unspecific finding (negative for infection), while an increasing uptake was interpreted as a positive finding for the presence of infection. Three-phase Tc-MDP bone scan was also routinely performed by standard technique. Sensitivity and specificity of early and delayed LeukoScan imaging were calculated., Results: Sensitivity for early and delayed imaging were 92.7%, while specificity was 78.4% for early imaging and 100% for delayed imaging approach. SPECT imaging did not add any significant information as regard to specificity in our experience. Eight false positive early scans were correctly diagnosed as negative at delayed imaging. Three false negative results were recorded. Sensitivity and specificity were similar when patients were on or off antibiotic therapy. Imaging was negative in all 12 controls., Conclusions: Our results, based on a large group of patients, suggest that delayed LeukoScan imaging is important in identifying false positive results detect at early imaging. Thus, a dual-time, 4 h early and 20-24 h delayed LeukoScan imaging approach should be recommended to increase the diagnostic accuracy of the scintigraphy, with the exception of patients with a negative early LeukoScan examination, in whom the acquisition of delayed imaging appears unnecessary. In our experience, concomitant antibiotic therapy did not influence the diagnostic value of LeukoScan.

Objective: To evaluate the prevalence and scan interpretation criteria useful in identifying non-tumoural F-FDG focal uptakes (potential pitfalls) in patients who had been previously treated for a malignant lymphoma studied by positron emission tomography (PET)., Materials: Nine hundred and ninety-six consecutive PET scans obtained in 706 patients with malignant lymphoma were reviewed. All patients had been previously treated by first-line chemo-radiotherapy, plus surgery when required, and were then studied by FDG PET to investigate suspected recurrence at doubtful or inconclusive conventional radiological imaging (ultrasound, computed tomography, magnetic resonance imaging). PET was obtained with patients in the fasted condition and after i.v. injection of 370 MBq of F-FDG; imaging was acquired 60-90 min later. In patients with focal FDG uptake the final diagnosis was reached on the basis of histological findings or long-term follow-up., Results: Thirty-one of 134 PET scans (23.1%) showing focal FDG uptake were diagnosed as non-tumoural radiotracer uptake, related to the presence of brown fat in seven cases, thymic hyperplasia in five, muscles contraction in four, lymph node unspecific inflammation in four, mediastinal/pulmonary unspecific inflammation in four, gastritis in two, colitis in two, bacterial abscess in one, lactating breast in one, and herpes zoster in one. Each of the above cited situations has been reported in the literature, generally in the form of sporadic reports, as a potential cause of misinterpretation (false positive) in reading a PET scan with the potential for incorrect patient management. An accurate diagnosis in these patients was important for the following therapeutic decision making., Conclusions: In the whole series of patients with treated malignant lymphoma, the prevalence of non-tumoural FDG focal uptake during follow-up was relatively low (3.1%); conversely, it was relatively high when considering the sub-group of 'positive' PET only (23.1%). The importance of knowing these situations in order to avoid misinterpretation in reading PET scans needs to be emphasized. In this light, an accurate patient's history and a skilful nuclear medicine physician are very important factors. For the same purpose, it is reasonable to think that the use of hybrid PET/CT tomographs could also play an important role in helping to identify non-tumoural FDG focal uptake.