Validation of automated motion assesment in the abdomen

Figure 2: Coronal slice with SPAMM lines (left) and visualization of line tracking in temporal direction (right). Methods The SPAMM prepulse imposes a line pattern on the magnetization. The distortion of the line pattern can be directly related to the motion that occurred between prepulse and readout. The SPAMM sequence was reconfigured for detecting aperiodic motion by removing the ECG trigger dependence, adding a constant delay between every prepulse and readout, and performing a full readout after every SPAMM prepulse (see figure 1). Determining the position of the SPAMM lines becomes a more difficult task in abdominal imaging compared to cardiac imaging; the SNR ratio is lower and there is no option of CSPAMM or reference images for line enhancement because of the lack of periodicity. Line tracking gives best results in temporal direction as there is better CNR and less interference of water-fat shift distortions (see figure 2). Abnormal small bowel motility is a frequent cause of a variety of gastrointestinal disorders [1]. Several diagnostic tests are available for the assessment of small bowel motility including scintigraphic techniques (evaluation of transit time), impedance monitoring and manometry [2]. Scintigraphy gives limited insight into motility while implementation of the latter two tests is hampered by their invasiveness. A motion sensitive MRI technique: SPatial Modulation of the Magnetization (SPAMM) was first described by Axel et.al. in 1989 [3] and developed for cardiac imaging. We reconfigured the technique for abdominal imaging making it single readout and non triggered. In this abstract we show three different methods to validate that this technique is able to estimate relatively small deformations in colon and small bowel.