The aim of this study was to prospectively compare whole-body PET/MR imaging and PET/CT, qualitatively and quantitatively, in oncologic patients and assess the confidence and degree of inter-and intraobserver agreement in anatomic lesion localization. Methods: Fifty patients referred for staging with known cancers underwent PET/CT with low-dose CT for attenuation correction immediately followed by PET/MR imaging with 2-point Dixon attenuation correction. PET/CT scans were obtained according to standard protocols (56 6 20 min after injection of an average 367 MBq of 18 F-FDG, 150 MBq of 68 Ga-DOTATATE, or 333.8 MBq of 18 F-fluoro-ethyl-choline; 2.5 min/bed position). PET/MR was performed with 5 min/bed position. Three dual-accredited nuclear medicine physicians/radiologists identified the lesions and assigned each to an exact anatomic location. The image quality, alignment, and confidence in anatomic localization of lesions were scored on a scale of 1-3 for PET/CT and PET/MR imaging. Quantitative analysis was performed by comparing the standardized uptake values. Intraclass correlation coefficients and the Wilcoxon signed-rank test were used to assess intra-and interobserver agreement in image quality, alignment, and confidence in lesion localization for the 2 modalities. Results: Two hundred twenty-seven tracer-avid lesions were identified in 50 patients. Of these, 225 were correctly identified on PET/CT and 227 on PET/MR imaging by all 3 observers. The confidence in anatomic localization improved by 5.1% when using PET/MR imaging, compared with PET/CT. The mean percentage interobserver agreement was 96% for PET/CT and 99% for PET/MR imaging, and intraobserver agreement in lesion localization across the 2 modalities was 93%. There was 10% (5/50 patients) improvement in local staging with PET/MR imaging, compared with PET/CT. Conclusion: In this first study, we show the effectiveness of whole-body PET/MR imaging in oncology. There is no statistically significant difference between PET/MR imaging and PET/CT in respect of confidence and degree of inter-and intraobserver agreement in anatomic lesion localization. The PET data on both modalities were similar; however, the observed superior soft-tissue resolution of MR imaging in head and neck, pelvis, and colorectal cancers and of CT in lung and mediastinal nodal disease points to future tailored use in these locations.

SPECT/CT is a useful tool for the evaluation of painful knee prosthesis in 85.5% of cases and helps in confirming mechanical loosening and in excluding other causes such as infection and patellofemoral osteoarthritis.

We present a case report of a patient with metastatic non-small cell lung cancer (NSCLC) who had a series of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scans for assessment of response to treatment. A restaging 18F-FDG PET/CT scan after six cycles showed increased FDG activity in the bone lesions with reduced activity in the lung and liver lesions. The increased bone activity was considered to be due to flare phenomenon rather than metastasis. A short interval follow up scan after 1 month was advised to confirm this interpretation but this repeat scan showed disease relapse. Although the flare phenomenon does exist, caution should be exercised in attributing increased tracer uptake in the lesions in patients with adenocarcinoma of lung and especially those who have received erlotinib during the course of their treatment. Distinguishing the 'flare phenomenon' and 'disease progression' is at times difficult but is important since misdiagnosis may result in an unnecessary delay in patient management.

Computed tomography head imaging in patients with non-localized headache has a low likelihood for any significant intracranial lesion. Therefore, it is essential to develop local standard operating procedures to promote better utilization of this type of imaging service.