Embolic infarction followed by serial bone SPECT and MR fusion images : the door to SPECT/MR

We recently experienced a case of cerebral infarction incidentally found by whole body bone scintigraphy for the detection of bone metastasis from renal cell carcinoma. Additional bone SPECT and brain MR fusion images clearly demonstrated the wedge-shaped uptake of tracer corresponded to the abnormal intensity reflecting subacute cerebral infarction. Follow-up bone scan and fused images with MRI showed complete resolution of the abnormal uptake in chronic phase. A breakdown in the normal blood-brain barrier results in abnormal ionic calcium flux into the cells following altered cell membrane integrity leading to precipitation of calcium salts which eventually binds to bone imaging tracer such as 99mTc-methylene diphosphonate. That is, increased accumulation of bone seeking agents represents lethal cell death. The recent development of software and hardware has enabled the fusion of functional and anatomic images. Image fusion between SPECT with various tracers and MRI is expected to provide clues as to the underlying cause of diseases and to decide our treatment planning in the near future

Dual-time-point 18F-FDG PET imaging for diagnosis of disease type and disease activity in patients with idiopathic interstitial pneumonia

Purpose Individual clinical courses of idiopathic interstitial pneumonia (IIP) are variable and difficult to predict because the pathology and disease activity are contingent, and chest computed tomography (CT) provides little information about disease activity. In this study, we applied dual-time-point [18F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET), commonly used for diagnosis of malignant tumors, to the differential diagnosis and prediction of disease progression in IIP patients. Methods Fifty patients with IIP, including idiopathic pulmonary fibrosis (IPF, n=21), nonspecific interstitial pneumonia (NSIP, n=18), and cryptogenic organizing pneumonia (COP, n=11), underwent 18F-FDG PET examinations at two time points: Scan 1 at 60 min (early imaging) and Scan 2 at 180 min (delayed imaging) after 18F-FDG injection. The standardized uptake values (SUV) at the two points and the retention index (RI-SUV) calculated from them were evaluated and compared with chest CT findings, disease progression, and disease types. To evaluate short term disease progression, all patients were examined pulmonary function test every 3 months for 1 year after 18F-FDG PET scanning. Results The early SUV for COP (2.47±0.74) was significantly higher than that for IPF (0.99±0.29, P=0.0002) or NSIP (1.22±0.44, P=0.0025). When an early SUV cut-off value of 1.5 and greater was used to distinguish COP from IPF and NSIP, the sensitivity, specificity, and accuracy were 90.9%, 94.3%, and 93.5%, respectively. The RI-SUV for IPF and NSIP lesions was significantly greater in patients with deteriorated pulmonary function after 1-year of follow-up (progressive group, 13.0±8.9%) than in cases without deterioration during the 1-year observation period (stable group, -16.8±5.9%, P<0.0001). However, the early SUV for all IIP types provided no additional information of disease progression. When an RI-SUV cut-off value of 0% and greater was used to distinguish progressive IIPs from stable IIPs, the sensitivity, specificity, and accuracy were 95.5%, 100%, and 97.8%, respectively. Conclusion Early-SUV and RI-SUV obtained from dual-time point 18F-FDG PET are useful parameter for the differential diagnosis and prediction of disease progression in patients with IIP