Utilizing the publicly available neuroimaging database enabled by Alzheimer’s disease Neuroimaging Initiative (ADNI; http://adni.loni.usc.edu/), we have compared the performance of automated classification algorithms that differentiate AD vs. normal subjects using Positron Emission Tomography (PET) with fluorodeoxyglucose (FDG). General linear model, scaled subprofile modeling and support vector machines were examined. Among the tested classification methods, support vector machine with Iterative Single Data Algorithm produced the best performance, i.e., sensitivity (0.84) × specificity (0.95), by 10-fold cross-validation. We have applied the same classification algorithm to four different datasets from ADNI, Health Science Centre (Winnipeg, Canada), Dong-A University Hospital (Busan, S. Korea) and Asan Medical Centre (Seoul, S. Korea). Our data analyses confirmed that the support vector machine with Iterative Single Data Algorithm showed the best performance in prediction of future development of AD from the prodromal stage (mild cognitive impairment), and that it was also sensitive to other types of dementia such as Parkinson’s Disease Dementia and Dementia with Lewy Bodies, and that perfusion imaging using single photon emission computed tomography may achieve a similar accuracy to that of FDG-PET.

Objectives To evaluate the effect of pre-scan blood glucose levels (BGL) on standardized uptake value (SUV) in 18 F-FDG-PET scan. Methods A literature review was performed in the MEDLINE, Embase, and Cochrane library databases. Multivariate regression analysis was performed on individual datum to investigate the correlation of BGL with SUV max and SUV mean adjusting for sex, age, body mass index (BMI), diabetes mellitus diagnosis, 18 F-FDG injected dose, and time interval. The ANOVA test was done to evaluate differences in SUV max or SUV mean among five different BGL groups (< 110, 110-125, 125-150, 150-200, and > 200 mg/dl). Results Individual data for a total of 20,807 SUV max and SUV mean measurements from 29 studies with 8380 patients was included in the analysis. Increased BGL is significantly correlated with decreased SUV max and SUV mean in brain (p < 0.001, p < 0.001,) and muscle (p < 0.001, p < 0.001) and increased SUV max and SUV mean in liver (p = 0.001, p = 0004) and blood pool (p = 0.008, p < 0.001). No significant correlation was found between BGL and SUV max or SUV mean in tumors. In the ANOVA test, all hyperglycemic groups had significantly lower SUVs compared with the euglycemic group in brain and muscle, and significantly higher SUVs in liver and blood pool. However, in tumors only the hyperglycemic group with BGL of > 200 mg/dl had significantly lower SUV max. Conclusion If BGL is lower than 200 mg/dl no interventions are needed for lowering BGL, unless the liver is the organ of interest. Future studies are needed to evaluate sensitivity and specificity of FDG-PET scan in diagnosis of malignant lesions in hyperglycemia.

Single-photon emission computed tomography (SPECT) has been a mainstay of nuclear medicine practice for several decades. More recently, combining the functional imaging available with SPECT and the anatomic imaging of computed tomography (CT) has gained more acceptance and proved useful in many clinical situations. Most vendors now offer integrated SPECT/CT systems that can perform both functions on one gantry and provide fused functional and anatomic data in a single imaging session. In addition to allowing anatomic localization of nuclear imaging findings, SPECT/CT also enables accurate and rapid attenuation correction of SPECT studies. These attributes have proved useful in many cardiac, general nuclear medicine, oncologic, and neurologic applications in which the SPECT results alone were inconclusive. Optimal clinical use of this rapidly emerging imaging modality requires an understanding of the fundamental principles of SPECT/CT, including quality control issues as well as potential pitfalls and limitations. The long-term clinical and economic effects of this technology have yet to be established.

Technetium-99m sestamibi imaging for parathyroid adenoma localization has been performed using both dual-tracer subtraction and double-phase single-tracer washout techniques. The relative accuracy of these two techniques is uncertain. We have developed a modified imaging technique which combines both approaches and have directly compared them in a series of patients with surgically explored hyperparathyroidism. Initial injection of (99m)Tc-pertechnetate 50 MBq was followed by continuous dynamic imaging of the anterior neck for 30 min. (99m)Tc-sestamibi 1,000 MBq was injected intravenously at the midpoint of the acquisition. Delayed images were performed after 2 h. We blindly reviewed 88 consecutive cases of surgically explored hyperparathyroidism that had undergone preoperative scintigraphic localization with this procedure. Images were reformatted to display subtraction-only, early/delayed sestamibi-only and combined images. Scans were reviewed in random order. Of the 68 cases with solitary parathyroid adenoma, the sestamibi-only images gave correct localization in 49 (72%) while there was a statistically significant improvement in accuracy using the subtraction-only images (58 of 68, 85%, P=0.05) and the combined images (61 of 68, 90%, P=0.0015). Reader confidence was also greater with the subtraction-only and combined images than with the sestamibi-only images. Scan performance with parathyroid hyperplasia was less satisfactory. Although the largest gland was usually correctly identified, hyperplasia was difficult to distinguish from a solitary adenoma. Dual-tracer subtraction parathyroid imaging is superior to double-phase sestamibi-only imaging. The washout data may provide additional information in some cases, however, and an approach that combines both techniques may be optimal.