Lesions, particularly a bilateral lesion, to this frontal bias resulted in very restricted scan paths with high levels of re-fixation.
The Martin Kulldorff's spatial scan test has several advantages over other local cluster detection tests, namely, a formal likelihood test statistic, avoidance of multiple testing, and not restricting scanning for clusters of a pre-specified size, thereby avoiding pre-selection bias [ 19].
Moreover, current scanning devices are still restricted to scanning small sample sizes only, which currently limits the practical applicability of this method.
While the original paper [ 3] is restricted to scanning for a single circular cluster, the method has been extended to ovals and other shapes as well as to space-time statistics in later works [ 4- 10].
Thereby restricting the scanning frequencies to less than 1% of the first resonance frequency.
The length of the interval, however, is restricted by the scanning range of the acoustic beam, which increases with depth.
Furthermore, the total number of detected photons was determined for each scan in a 20% energy window around 140 keV to estimate the sensitivity gain achieved by restricting the scan volume.
We also evaluated whether the number of space-time signals can be reduced by restricting the scan statistic in space or time.
In order to quantify improvements in signal-to-noise ratio by restricting the scan volume, a physical cardiac phantom was used.
Improvements due to restricting the scan area, in terms of sensitivity and resolution, were determined with a resolution phantom, whereas improvements in contrast-to-noise ratio were measured in scans of a mouse myocardial phantom containing a cold lesion.
