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We evaluated the labeling stability of several alternative meals that could be used to perform solid-phase gastric emptying study. Cooked egg whites labeled with technetium-99m sulfur colloid served as a control. Packaged instant oatmeal and instant mashed potatoes were prepared by adding hot water. Cheddar cheese was melted. Peanut butter was added to bread. The different meals were mixed with technetium-99m sulfur colloid (2.2–3.7 MBq), chopped into small pieces and placed in a glass tube containing gastric juice. Four samples of each meal were analyzed after 1 and 4 h of agitation with a 3-D rotator (two samples per time point). The meal samples were washed with 2 ml of saline and filtered using a blood transfusion filter. The activity in each sample before and after filtering was assayed in a dose calibrator. The percentage of initial radioactivity remaining with the meal of admixture with gastric juice was measured and the average of the two samples was taken. The percentage of activity bound to the solid phase was 98.2±1.9, 95.6±1.1, 62.1±1.7, 41.8±0.6, and 74.5±3.8 at 1 h and 98.5±1.0, 95.8±2.6, 77.2±6.8, 55.5±3.4 and 40.2±22.1 at 4 h for egg whites, cheese, oatmeal, mashed potatoes and peanut butter respectively. For egg whites and cheese, there was no significant difference between the values at 1 and 4 h (P>0.8). Cheddar cheese provides an alternative meal for assessing solid gastric emptying in children comparable to egg whites. Oatmeal and mashed potatoes had low and variable labeling stability and are not recommended. In view of the significant proportion of pediatric patients who refuse to eat scrambled eggs or have allergy to eggs, the availability of other meal choices is essential. The versatility of cheddar cheese, which can be added to macaroni or as a topping on pizza, makes it a useful alternative to labeled eggs.

Skeletal positron emission tomography (PET) with fluorine-18 (18F) sodium fluoride (18F NaF) is an alternative to technetium-99m (99mTc)methylene diphosphonate (MDP) scintigraphy. Experience with pediatric PET is sparse, primarily in oncology. This study assesses the role of 18F NaF in evaluating young patients with back pain.

We explore the feasibility of merging independent data sets to mitigate volume anisotropy intrinsic to tomosynthetic reconstructions. Two independent sets of orthogonally oriented projection data are obtained, respectively, from a hand phantom and from frozen breast tissues. Both objects are enclosed within radiolucent containers containing multiple fiducial reference objects. The latter facilitates registration of multiple projections produced by incrementally moving the x-ray source relative to the object about a single axis through a fixed series of angles. These data encompass maximum angular disparities up to 90 deg for each projection series. The resulting data are projectively transformed and nonlinearly processed using tuned-aperture computed tomography to yield a number of contiguous slices equal to the linear resolution of the sampled projections measured in pixels. The resulting slice data are then corrected for differential magnification, appropriately rotated, and linearly merged to yield a relatively complete, volumetrically isotropic representation of the phantom that could be visualized from any desired angle with negligible apparent tomosynthetic distortion. The resulting displays are evaluated subjectively and compared quantitatively with control images produced from optimum projection geometries. The results are consistent with the hypothesis that volume anisotropy intrinsic to tomosynthetic reconstructions can be minimized through integration of contiguously sampled orthogonal projections. © 2003 SPIE and IS&T.

The purpose of this study was to investigate the various phases of gastric emptying using a dual-isotope liquid-solid meal ([99mTc]Sc egg sandwich and [111In]DPTA in water) and continuous acquisition in the left anterior oblique view. The study groups consisted of 10 normal controls and 20 diabetics with symptoms suggestive of diabetic gastroparesis. Solid-phase emptying in both groups almost always had a lag phase followed by linear emptying. Liquid-phase emptying was biexponential in 4/10 normals and 12/20 diabetics, with a short early rapid emptying rate (meanT1/2=48 min in normals and 79 min in diabetics). Solid emptying was delayed in 10, normal in eight, and rapid in two diabetics. Liquid emptying was delayed in 9/10 diabetics who had delayed solid emptying. Diabetics as a group had a significantly delayed solid lag phase (P<0.025), rate of emptying (P<0.05) and percent emptying at 90 min (P<0.025) compared to normal controls. Diabetic liquid emptying was also significantly delayed (P<0.025). The second component of liquid emptying strongly correlated with the solid rate of emptying (r=0.826 in normals and 0.855 in diabetics). Continuous acquisition of gastric emptying studies in the LAO view has allowed us to better define the various phases of solid and liquid gastric emptying.

The geometric mean is the recommended method for calculating gastric emptying in adults to correct for variable attenuation during the study. In children, it has been reported that a single posterior acquisition is sufficient. Our objective was to evaluate the relation between the values of gastric emptying in children obtained by posterior view only and by the geometric mean of conjugate anterior and posterior views.

The rotating display is a useful method for reviewing single photon emission computed tomography (SPECT) data. This study evaluated the requirements for a subjectively pleasing and useful implementation of this technique. Twelve SPECT data sets were modified and viewed by several observers who recorded the minimum framing rates for apparent smooth rotation, 3D effect, effects of image size, and other parameters. The results showed that a minimum of 16 frames was needed for a useful display. Smaller image sizes and more frames were preferred. The recommended minimal framing rate for a 64-frame study is 16–17 frames per second and for a 32-frame study, 12–13 frames per second. Other enhancements also were useful.