Measurement of gallbladder volume and dynamics by combined SPECT and planar scintigraphy

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Gastroenterology

Background:

• Accurate measurement of gallbladder volume is crucial for diagnosing and managing various hepatobiliary conditions.
• Existing methods for assessing gallbladder volume and function may have limitations in precision or invasiveness.

Purpose of the Study:

• To develop and validate a novel three-dimensional single photon emission computed tomography (3D SPECT) technique for precise gallbladder volume measurement.
• To evaluate gallbladder emptying parameters using the developed SPECT method in conjunction with a planar technique.

Main Methods:

• Validation of the 3D SPECT technique using a body phantom with a balloon representing the gallbladder, inflated to known volumes.
• Calculation of SPECT volume by summing voxels above a count threshold in transaxial slices.
• Assessment of gallbladder fasting volume and post-cholecystokinin octapeptide (CCK) induced emptying in nine normal subjects using a technetium-99m-labelled hepatobiliary agent.

Main Results:

• A high linear correlation (r = 0.99) was observed between SPECT-derived and true gallbladder volumes (15-90 ml).
• The mean fasting gallbladder volume in normal subjects was 26 +/- 2 ml (range 18-39 ml).
• Following CCK infusion, the mean gallbladder ejection rate was 1.2 +/- 0.2 ml/min, with a residual volume of 12 +/- 2 ml.

Conclusions:

• 3D SPECT provides an accurate and noninvasive method for measuring gallbladder volume.
• The combined SPECT and planar technique allows for reliable evaluation of gallbladder emptying dynamics.
• This novel SPECT approach has significant potential for clinical applications in hepatobiliary diagnostics.