2.5. Study Procedure
abdominal pain
Subjects reported to Purdue MRI Facility for two visits, at least six days apart. Subjects consumed a low-fiber dinner the night before the test feeding, fasted twelve hours prior to their visit and avoided drinking water three hours prior to the visit. On the day of the visit, scans were performed using a Magnetom 3T Prisma MRI scanner (Siemens Healthineers, Erlangen, Germany). Large flex surface coil (18-channel) and spine coil (32-channel) were used to acquire the coverage of the entire abdomen. Coronal abdominal images were acquired with HASTE sequence (repletion time (TR) = 1200 ms; echo time (TE) = 101 ms; flip angle (FA) = 160°; field-of-view (FOV) = 340 × 340 mm; in-plane resolution = 1.3 × 1.3 mm; 45 coronal slices; slice thickness = 3 mm; GRAPPA = 3). The prospective navigator-triggered HASTE sequence took about 4 min. An initial scan was performed to acquire images of the baseline empty stomach. Subjects then consumed a milk dose, and the amount of milk was calculated in ml using the following formula:One cup of milk, or 245 mL, contains approximately 11 g of lactose. Subjects consumed 0.5 g of lactose per kg body weight. The amount of milk (mL) and lactose (g) consumed by subjects were the same during the two MRI visits. Coronal MRI images were acquired at 10, 30, 60 and 120 min with HASTE sequence after the consumption of milk. Subjects also rated and recorded their abdominal pain at 0, 30, 60, 90 and 120 min using a six-point Likert scale. The scale ranged from 0 to 5, where 0 indicated no symptom, 1 was for slight abdominal pain, 2 for mild, 3 for moderate, 4 for moderately severe and 5 for severe abdominal pain.