Radiology - Research Publications
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ItemHybrid imaging is the future of molecular imaging.(Department of Biomedical Imaging, University of Malaya, Malaysia, 2007-07)Correlative imaging has long been used in clinical practice and particularly for the interpretation of nuclear medicine studies wherein detailed anatomical information is often lacking. Previously, side-by-side comparison or software co-registration techniques were applied but suffered from technical limitations related to the differing geometries of the imaging equipment, differences in the positioning of patients and displacement of mobile structures between studies. The development of the first hybrid PET and CT device struck a chord with the medical imaging community that is still ringing loudly throughout the world. So successful has been the concept of PET-CT that none of the major medical imaging manufacturers now offers stand-alone PET scanners. Following close behind this success, SPECT-CT devices have recently been adopted by the nuclear medicine community, already compelled by the benefits of hybrid imaging through their experience with PET-CT. Recent reports of adaptation of PET detectors to operate within the strong magnetic field of MRI scanners have generated further enthusiasm. Prototype PET-MRI devices are now in development. The complementary anatomical, functional and molecular information provided by these techniques can now be presented in an intuitive and aesthetically-pleasing format. This has made end-users more comfortable with the results of functional imaging techniques than when the same information is presented independently. Despite the primacy of anatomical imaging for locoregional disease definition, the molecular characterisation available from PET and SPECT offers unique complementary information for cancer evaluation. A new era of cancer imaging, when hybrid imaging will be the primary diagnostic tool, is approaching.
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ItemUse of FDG PET/CT for investigation of febrile neutropenia: evaluation in high-risk cancer patients(SPRINGER, 2012-08)PURPOSE: Febrile neutropenia (FNP) is a frequent complication of cancer care and evaluation often fails to identify a cause. [(18) F]FDG PET/CT has the potential to identify inflammatory and infectious foci, but its potential role as an investigation for persistent FNP has not previously been explored. The aim of this study was to prospectively evaluate the clinical utility of FDG PET/CT in patients with cancer and severe neutropenia and five or more days of persistent fever despite antibiotic therapy. METHODS: Adult patients with a diagnosis of an underlying malignancy and persistent FNP (temperature ≥38°C and neutrophil count <500 cells/μl for 5 days) underwent FDG PET/CT as an adjunct to conventional evaluation and management. RESULTS: The study group comprised 20 patients with FNP who fulfilled the eligibility criteria and underwent FDG PET/CT in addition to conventional evaluation. The median neutrophil count on the day of the FDG PET/CT scan was 30 cells/μl (range 0-730 cells/μl). Conventional evaluation identified 14 distinct sites of infection, 13 (93 %) of which were also identified by FDG PET/CT, including all deep tissue infections. FDG PET/CT identified 9 additional likely infection sites, 8 of which were subsequently confirmed as "true positives" by further investigations. FDG PET/CT was deemed to be of 'high' clinical impact in 15 of the 20 patients (75 %). CONCLUSION: This study supports the utility of FDG PET/CT scanning in severely neutropenic patients with five or more days of fever. Further evaluation of the contribution of FDG PET/CT in the management of FNP across a range of underlying malignancies is required.
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ItemEarly therapeutic response assessment by 18FDG-positron emissiontomography during chemotherapy in patients with diffuse large B-celllymphoma: isolated residual positivity involving bone is not usually a predictor of subsequent treatment failure(Taylor & Francis, 2007-03)Residual 2-fluoro-2-deoxyglucose (FDG) – positron emission tomography (PET) positivity during treatment of patients withdiffuse large B-cell lymphoma (DLBLC) prospectively identifies a subgroup at high likelihood of subsequent treatmentfailure. A single institution clinical audit of FDG-PET performance for this indication was undertaken for patients withDLBCL treated with anthracycline-based chemotherapy+radiotherapy. Of 45 eligible patients, 14 (31%) were PETpositiveafter a median of three chemotherapy cycles (range 1 – 5), of which 10 (71%) progressed at a median of 6.5 months.An interim positive PET was a statistically significant adverse prognostic factor for treatment failure (P=0.0001, log-rankanalysis) with a hazard ratio for a positive interim-treatment PET of 9 (95% confidence interval 4 – 55) and positivepredictive value of 71% and negative predictive value of 90%. Notably, four patients with low-grade FDG-avidity limited tosites previously involved by biopsy-proven osseous lymphoma, remain progression-free (median follow-up 62 months). LowgradeFDG-avidity on interim restaging at sites of bone involvement by DLBCL at diagnosis, appears to be less predictive ofdisease progression than residual nodal or extra-nodal soft tissue abnormality by PET.
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ItemHigh management impact of Ga-68 DOTATATE (GaTate) PET/CT for imaging neuroendocrine and other somatostatin expressing tumours(WILEY, 2012-02)INTRODUCTION: Ga-68 DOTATATE (Ga-octreotate, GaTate) positron emission tomography (PET)/CT has multiple advantages compared with conventional and In-111 octreotide imaging for neuroendocrine tumours and other somatostatin-receptor expressing tumours. This study assesses the management impact of incremental diagnostic information obtained from this technique compared with conventional staging. METHODS: Fifty-nine GaTate PET/CT studies were performed over an 18-month period (52 proven or suspected gastro-entero-pancreatic or bronchial neuroendocrine tumours and seven neural crest/mesenchymal tumours). A retrospective blinded review was performed on the number of abnormalities (1, 2-5 or >5) within defined regions with comparison to conventional imaging to assess incremental diagnostic information. Subsequent management impact (high, moderate or low) was determined by clinical review and follow up to assess pre-PET stage, treatment intent and post-PET management change. RESULTS: Eighty-eight percent of GaTate studies were abnormal. Compared with conventional and In-111 octreotide imaging, additional information was provided by GaTate PET/CT in 68 and 83% of patients, respectively. Management impact was high (inter-modality change) in 47%, moderate (intra-modality change) in 10% and low in 41% (not assessable in 2%). High management impact included directing patients to curative surgery by identifying a primary site and directing patients with multiple metastases to systemic therapy. CONCLUSION: GaTate PET/CT imaging provides additional diagnostic information in a high proportion of patients with consequent high management impact. GaTate PET/CT could replace (1)In-111 octreotide scintigraphy at centres where it is available given its superior accuracy, faster acquisition and lower radiation exposure. Rapid implementation could be achieved by allowing substitutional funding in the Medicare Benefit Schedule.