Positron emission tomography (PET) and single-photon emission tomography (SPET) are cross-sectional, quantitative functional imaging modalities in routine use in oncology for the initial staging of cancer, the assessment of patients with recurrent or residual disease and, more recently, for monitoring tumour response to therapy. Both PET and SPET can track tumour biological and metabolic changes caused by therapy or by disease progression, which usually precede the anatomical alterations conventionally detected by anatomical imaging methods. These highly sensitive functional imaging modalities have been used for the early assessment of subclinical tumour response, the evaluation of therapy after its completion and the detection of viable recurrent or relapsing tumour. Timely assessment of response to treatment using PET and SPET may result in modifications in treatment planning and individualisation of therapy and may have prognostic value for the long-term outcome. This review attempts to summarise the current data available on the expanding role of SPET and PET, using a variety of tracers, in monitoring tumour response to therapy in a wide range of malignancies, with emphasis on their clinical impact.

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Objective Regadenoson is the first Food and Drug Administration-approved selective A2A adenosine receptor agonist used in myocardial perfusion imaging. Its main benefits are its simplified and brief protocol, along with the ability to be administered safely in patients with asthma or chronic obstructive pulmonary disease of moderate severity. This study aims to identify any potential benefits of regadenoson, regarding the frequency of adverse reactions and its tolerability, over dipyridamole. Methods This is a randomized controlled study of 200 patients scheduled for medium to high-risk noncardiac surgery, of whom 100 were stressed with regadenoson (study group) and the rest with dipyridamole (control group). Results A greater proportion of adverse reactions was recorded in the regadenoson group as compared to the dipyridamole group (53 vs. 36%; P = 0.023), though the duration of most adverse reactions was shorter in the regadenoson group. Dyspnea (P < 0.001) and gastrointestinal disturbances (P = 0.001) were significantly more frequent in the regadenoson group. The use of aminophylline in patients who developed any adverse events was similar in the two groups (P > 0.05). When multiple regression analyses were performed, differences in adverse reactions between the two groups were no longer significant (odds ratio = 1.96; 95% confidence interval, 0.88–3.25; P = 0.11). Conclusion In our group of patients scheduled for myocardial perfusion imaging for preoperative assessment, the two agents, regadenoson and dipyridamole, have no significant differences in the frequency of mild adverse reactions and in aminophylline use, with regadenoson also having the advantage of faster symptom resolution. Nevertheless, dipyridamole can be considered as a well-tolerated and low-cost alternative.

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[18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been reported to have a low sensitivity in the initial diagnosis of bronchoalveolar carcinoma (BAC) due to BAC’s low metabolic activity. The aim of this study was to assess the value of [18F]FDG-PET/CT in the detection of BAC recurrence. Between February 2007 and September 2011, the [18F]FDG-PET/CT scans that were performed on patients with known, histologically proven BAC were studied. A total of 24 [18F]FDG-PET/CT scans were performed in 22 patients, including 16 males and 6 females, with a mean age of 65±9 years. Among the scans, 15 were performed to assess for possible recurrence with equivocal findings in conventional imaging methods and 9 for restaging post-therapy. In all cases conventional imaging studies (CT and MRI) were performed 5–30 days prior to PET/CT. Among the 24 [18F]FDG-PET/CT scans, 18 were positive and 6 negative. Among the 15 [18F]FDG-PET/CT scans performed for suspected recurrence, 34 lesions were detected and the mean maximum standardized uptake value (SUVmax) was 6.8±3.26. In nine scans, upstaging was observed, while two were in agreement with the findings of the conventional modalities. A greater number of lesions were detected in two scans and fewer lesions were detected in one, with no change in staging. Only one scan was negative. By contrast, in patients examined for restaging, there were only five lesions with a mean SUVmax of 4.86±3.18. Agreement between the findings of [18F]FDG-PET/CT and the conventional modalities was observed in 8 out of 9 cases. Although [18F]FDG-PET/CT has been reported to have a low sensitivity in the initial diagnosis of BAC, the present results indicate that when there is recurrence, the lesions become [18F]FDG avid. [18F]FDG-PET/CT may provide further information in patients evaluated for recurrence and thus improve patient management.

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