Simultaneous 13C/14C dual isotope breath test measurement of gastric emptying of solid and liquid in normal subjects and patients: comparison with scintigraphy

Abstract

Background: To develop a simple method for simultaneous solid and liquid gastric emptying assessment using a dual isotope labelled breath test.

Material and methods: 13 patients were given 100 g ground beef labelled with 25 MBq (99m)Tc sulphur colloid and 74 KBq (14)C octanoic acid, and 150 ml 10% glucose drink labelled with 8 MBq (67)Ga citrate and 150 mg (13)C acetate. 10 normal volunteers were given the same test meals but labelled with (14)C and (13)C only. Breath was collected at baseline and regularly for 4 hours. The (14)CO(2) and (13)CO(2) activity was measured with liquid scintillation counting and mass spectroscopy. The times to maximum (14)CO(2) and (13)CO(2), were determined. Comparison was made between times to maximum (14)CO(2) with scintigraphic retention of (99m)Tc at 100 minutes and times to maximum (13)CO(2) with the scintigraphic half-clearance time of (67)Ga.

Results: For the solid meal, the times to maximum (14)CO(2) were: 60-120 minutes in the 8 patients with normal gastric emptying of (99m)Tc; 75-145 minutes for the 10 healthy volunteers; 75-180 minutes for the remaining 5 patients with abnormal gastric emptying of (99m)Tc. There was a weak but significant correlation (r = 0.56, p < 0.025) between the time to maximum (14)CO(2) and gastric retention of (99m)Tc at 100 minutes. For the liquid meal, times to maximum (13)CO(2) were: 20-35 minutes for the 4 with normal gastric emptying of (67)Ga; 15-40 minutes for the 10 healthy volunteers; 20-75 minutes for the remaining 9 patients with abnormal gastric emptying of (67)Ga. There was a strong and significant correlation (r = 0.88, p < 0.005) between times to maximum (13)CO(2) and gastric half-clearance time of (67)Ga.

Conclusions: Breath tests utilising test meals labelled with *C isotopes are valid alternatives to scintigraphic studies using (99m)Tc and (67)Ga for the simultaneous assessment of gastric emptying of solids and liquids.