1 / 19

Is the 2 hr delayed Imaging really Needed in Gastric Emptying Scintigraphy ?

Is the 2 hr delayed Imaging really Needed in Gastric Emptying Scintigraphy ?. Kyung Hoon Hwang, Wonsick Choe, Jong Ho Kim and Minki Yoon Dept. of Nuclear Medicine, Gachon Medical School, Incheon, Korea. Introduction.

beate
Download Presentation

Is the 2 hr delayed Imaging really Needed in Gastric Emptying Scintigraphy ?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Is the 2 hr delayed Imaging really Needed in Gastric Emptying Scintigraphy ? Kyung Hoon Hwang, Wonsick Choe, Jong Ho Kim and Minki Yoon Dept. of Nuclear Medicine, Gachon Medical School, Incheon, Korea

  2. Introduction • Gastric emptying (GE) scintigraphy is the well known physiologic study evaluating gastric motility. • GE values may be fit by adequate mathematical functions, thus, divergent mathematical models have been suggested.

  3. Background • In most nuclear medicine practice, 2-hr delayed images are routinely taken for GE scintigraphy. • We investigated whether the 2-hr delayed GE values can be replaced by the calculated values using the simplified fitting equation in patients with normal to moderately delayed GE time.

  4. Mathematical Models - I • Two most famous models 1) Elashoff Model - Power Exponential Function Y(t) = 2(-t/Thalf) 2) Siegel Model - Modified Power Exponential Function Y(t) = 1-(1-e-kt) 

  5. Mathematical Models - II • Mathematical fitting of patient’s GE data to the known power exponential functions has been unsatisfactory. • Lag phase • Geometric change in attenuation • Besides, Known mathematical fitting models are complex and difficult to apply in practice.

  6. Mathematical Model - III • We modified the well-known Siegel equation into more simple form fitted in only late phase. Y(t) = 1-(1-e-kt) Y(t)  e(-kt)A in late phase Modified to -------- A: Y-intercept extrapolated from late emptying curve (usually >1).

  7. Mathematical Model - IV • Then, applying Logarithm, • We can obtain the slope of the equation by linear regression from late (60 to 90 min) GE time data. - FR120 (fractional retention at 120 min) or other parameters can be predicted by this simple equation. Ln Y(t) = -kt + ln A

  8. Y(t) = e(-kt)A A h

  9. Methods - I • GE time was measured using solid food (Fried eggs containing Tc-99m DTPA) • GE time data of 74 patients (M:F = 22:52) who have T1/2 less than 200 min and FR120 less than 75% were retrospectively analyzed.

  10. Geometric Mean Count was measured in the ROI of stomach.

  11. Methods - II • The predicted T1/2 and FR120 were calculated from linear regression of late GE values (60, 75 and 90 min), using modified exponential model. • The correlation between the predicted GE values and the measured ones was evaluated using Medcalc statistical software

  12. Ln Predicted FR120 = e-0.673 = 0.510 (51.0%) Measured FR120 = 0.507 (50.7%)

  13. Results • A very significant correlation was found between the predicted FR120 and the measured one (r=0.95, p<0.0001). • There was also a significant correlation between the predicted T1/2 and the measured one (r=0.81, p<0.0001).

  14. R=0.9515, p<0.0001

  15. R=0.8137, p<0.0001 Predicted T1/2 T1/2

  16. Conclusion • Highly reliable FR120 and T1/2 could be predicted from the late GE time values by using the modified exponential function. • Therefore, 2-hr delayed measurement of GE time may be replaced by the values calculated from the late GE time values

  17. THE END

More Related