Role of 18F-DOPA PET/CT imaging in congenital hyperinsulinism

Congenital hyperinsulinism is a leading cause of severe hypoglycaemia in the newborn period. There are two (diffuse and focal) histological subtypes of congenital hyperinsulinism. The diffuse form affects the entire pancreas and if medically unresponsive will require a near total (95%–98%) pancreatectomy. The focal form affects only a small region of the pancreas (with the rest of the pancreas being normal in endocrine and exocrine function) and only requires a limited pancreatectomy. This limited section of the focal lesion has the potential for curing the patient. Thus the pre-operative differentiation of these two subgroups is extremely important. Recent advances in Fluorine-18-L-dihydroxyphenylalanine positron emission tomography (¹⁸F-DOPA PET/CT) have radically changed the clinical approach to patient with congenital hyperinsulinism. In most patients this novel imaging technique is able to offer precise pre-operative localisation of the focal lesion, thus guiding the extent of surgical resection.     

18F‐FDG PET/CT influences management in patients with known or suspected pancreatic cancer

Background: The aims of this study were (i) to assess and validate the incremental information of positron emission tomography/computed tomography (PET/CT) over conventional staging investigations (CSI) and (ii) to assess the management impact of PET/CT in patients with known or suspected pancreatic cancer. Methods: Between October 2007 and September 2008, 22 PET/CT scans were performed using a dedicated PET/CT scanner in 21 patients with known or suspected pancreatic cancer. Follow up was used to reconcile discordance between PET/CT and CSI. The pre‐PET/CT management plan and/or intent were prospectively recorded in all scans. The post‐PET/CT management plan was determined from the medical record and/or discussions with treating clinicians. The management impact of PET/CT was classified as high, medium, low or none defined using Australian and New Zealand Association of Physicians in Nuclear Medicine PET data collection project criteria. Results: PET/CT and CSI were discordant in 14/22 (64%: 95% CI; 43–84%) scans. Of the 14 discordant scans, PET/CT assessment was correct in eight, conventional imaging in four and there was insufficient information in two. Overall, PET/CT management impact was classified as high (n= 6), medium (n= 3), low (n= 9) or none (n= 4). Significant changes in management (high or medium impact) were induced by PET/CT in 9/22 scans (41%: 95% CI; 20–62%) predominantly by correctly modifying the disease extent. Conclusion: PET/CT has an incremental benefit over CSI and has a significant impact on management in patients with known or suspected pancreatic cancer. PET/CT merits consideration as part of the non‐invasive evaluation of patients with known or suspected pancreatic cancer.     

Standardised uptake value of 18F‐FDG on staging PET/CT in newly diagnosed patients with different subtypes of non‐Hodgkin’s lymphoma

Objectives: Positron emission tomography using 2‐[fluorine‐18]‐fluoro‐2‐deoxy‐d ‐glucose (¹⁸F‐FDG) is considered to be the most beneficial imaging method for staging patients with non‐Hodgkin’s lymphoma (NHL). The intensity of ¹⁸F‐FDG accumulation may be determined by calculating the so‐called standardised uptake value (SUV). The study aimed at assessing the benefit of SUV_max determination in staging ¹⁸F‐FDG PET/CT in untreated patients with NHL. Methods: One hundred and forty‐nine initial staging ¹⁸F‐FDG PET/CT scans performed in patients with NHL between January 2007 and August 2009 were assessed, and the SUV_max was determined. Results: The highest mean and median values of SUV_max were observed in patients with diffuse large B‐cell lymphoma (DLBCL), the lowest mean and median values were found in small lymphocytic lymphoma. The overlap in SUV_max < 10 between DLBCL and the other subgroups of NHL was very significant. Statistically, no correlation was found between the lactate dehydrogenase and SUV_max values. On the other hand, a correlation of the Ki‐67 proliferative index of tumour cells and SUV_max was revealed (r = 0.409, P < 0.001). The geometric mean of SUV_max in patients with Ki‐67 ≤ 60 and those with Ki‐67 > 60 was 8.8 and 14.3, respectively (P < 0.001). Conclusions: The results confirm that SUV_max is not beneficial for making a more precise diagnosis in most patients with NHL. Correlation of SUV_max with the Ki‐67 values suggests that SUV_max might have a prognostic values in NHL.     

The role of 18F-FDG PET/CT imaging in Waldenstrom macroglobulinemia

Disease assessment in WM is dependent on the quantification of the IgM monoclonal protein and percent involvement of the bone marrow. There is a need for imaging studies that objectively measure tumor load in these patients. In this study, we sought to examine the role of combined FDG-PET/CT imaging in the detection of tumor load and in the assessment of response to therapy. Thirty-five patients were enrolled on a prospective study using bortezomib and rituximab therapy and were included in this study because they completed a pre- and post-treatment FDG-PET/CT imaging at one facility (12 newly diagnosed and 23 relapsed/refractory). The use of combined FDG-PET/CT imaging showed positive findings in 83% of patients with WM, unlike prior studies using conventional imaging that indicate that only 20% of patients have lymphadenopathy or hepatosplenomegaly. Moreover, 43% of patients had abnormal bone marrow uptake on FDG-PET imaging that can potentially help in the assessment of their tumor load, especially with heterogenous sampling of the bone marrow. There was no statistical correlation between EORTC response criteria for FDG-PET/CT and response by monoclonal protein. This is the first study to examine the role of FDG-PET/CT imaging in WM. Future studies should examine the role of FDG-PET/CT in conjunction with monoclonal protein response in the assessment of progression-free survival in patients with WM.