Imaging and quantification of gastric emptying using a general purpose full ring CZT SPECT scanner

Introduction: Investigation of gastric emptying is a routine referral for nuclear medicine instituitons. Generally these studies are performed in planar technique drawing ROIs in the serial images from 0 up to 240 minutes. In new full ring CZT scanners planar imaging is replaced by SPECT offering high countrates and excellent 3D image quality without problematic overlaying structures.

The purpose of our study was to evaluate the use of a CZT SPECT/CT general purpose gamma camera in the diagnostic workup for patients with gastric emptying disorders.

Methods: In this pilot study we investigated four female patients with a mean age of 33 years being referred to our institution for routine gastric emptying studies. The patients suffered from abdominal cramps, two of them had diabetes. Each patient received a rice dish having been labeled with Tc-99m macroalbumin particles with a mean dose of 69.5 MBq stirred into 205 g cooked rice. SPECT acquisitons were taken 30, 60, 90, 120 150 and 240 minutes after serving the meal. A volume of interest was drawn corresponding to the gastric circumference in the early image directly after consumption. Using the MIM software specialized for 3D datasets by SPECTRUM Dynamics the countrate in the early gastric VOI was compared to the corresponding VOIs in the serial 3D-SPECT images.

Results: In comparison to the literature (Hansrod S in Nucl. Med. Commun. 07/2020, Farrell in JNuclMedTech 06/2019) two patients showed normal results, one patient was close to normal whereas one showed pathologic results with a remaining proportional countrate of 41 % at 120 minutes and 13.2 % at 240 minutes after taking the meal correlating with an elevated t ½ up to 91 minutes. The results are being summed up in the following chart.

Caption: Proportional counts in the beginning and the end. Remaining countrate in the VOI at 30 to 240 Minutes. Time when half the activity remaining in the VOI.

Conclusions: SPECT using a general purpose full ring CZT SPECT scanner seems to be helpful in the diagnostic workup of patients with gastric emptying disorders. The workflow including high quality images as well as a 3D quantification is feasible even in daily routine.

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