A Note on Image Contents
For best and complete results, the image should show the entire liver and the entire pelvis. This is standard practice for a lateral abdomen, so should not be considered a restriction.
A Note on the Liver Measurement
References such as J. Choi et al, 2013, A. Cha et al, 2018, S. Lee et al, 2019, S. Kim et al, 2018, and S. Hong et al, 2017 all measure liver size from a lateral radiograph by dividing the “liver Length” (see references for definition) by the length of the T11 vertebra. In our implementation, we make this measurement on the Lateral Abdomen radiograph where we also measure the lumbar spine. We use the average length of the first five lumbar vertebrae (L1 through L5) as a more stable scale reference. In our internal study of 150 mixed breed dogs, we determined a conversion factor between this average lumbar vertebra length, and the length of T11. In our study, T11 was 78.0% the length of the average lumbar vertebra (standard deviation of 4.7%). So, we use this conversion factor to compute liver size as defined in these reference articles. J. Choi et al, 2013 give values for normal liver size. We declare a liver to be ‘enlarged’ when it exceeds this normal value by 20%, and we declare a liver to be ‘micro’ when it is less than 60% of this normal size. Compensation is made for brachycephalic breeds (if that information is supplied). Hence the normal range for liver size in this scheme is 3.10 < Liver < 6.20 for brachycephalic dogs, and 3.24 < Liver < 6.48 for other breeds.
A Note on the Colon Measurement
The colon is measured at one location (usually under L6 or L7). If the colon is not detectable or is small, the measure may not appear at all. This measure is only of interest in the case of a colon filled with gas or fecal material so that we can judge if it is enlarged. The numerical value is the width divided by the average length of the L1 thru L5 vertebrae.
How ‘Rotation’ is Judged
We locate the centers of the femur heads and based on the length and orientation of the line segment that connects them, we can detect of the animal was ‘rotated’ on the table. In normal positioning for a lateral abdomen radiograph, the femur heads will not appear superimposed, due to the fact that the central x-ray beam is located more towards the center of the dog, and the dog’s thickness (spacing between the two femur heads). But the line segment connecting the centers of the femur heads should point back towards the location of the central beam of the x-ray generator, which we generally assume to be about in the center of the image. Hence, based on the angle in the image of this line segment, and the length of this line segment, we can determine bounds on the dog’s ‘rotation’ on the table.
A Note on our Circling of Conditions
The red ellipse that we display is meant as a quick visual guide to locate a detected condition. Its exact location and shape may be approximate. It is not intended that these ellipses have a precise spatial meaning - they are just there to alert you visually that something was recognized. Also, there is only one such ellipse drawn per condition - and it is not guaranteed to encircle all occurances of that condition, but rather, to highlight one instance. For example, in the case of Renal Mineralization in both kidneys, the system may only circle one of the kidneys, not both. Note that with editing tools we allow you to adjust the location and shape of these ellipses (also you can completely remove them or add them).
Conditions Marked with the Yellow Color
The yellow color indicates that the condition could not be determined from this image. This can be due to a few different factors, e.g. the image was cropped or did not contain the portion of anatomy needed, or the radiograph quality precluded the detection, or other reasons. In some cases, it may mean our algorithm is not complete for that item, but it’s detection will be enabled in a future release (e.g. the L7-S1 disc).
A Note on ‘Show Stopper’ Conditions
There are a few conditions, which if detected, will cause the system to stop analyzing the image. For example, if the dog is found to be pregnant, then we don’t check further for other things (like calculi, etc). Likewise, if GDV or a ‘barium study’ is detected, we don’t check for all other things. In these cases, you will see many conditions marked in yellow - to indicate that they were not checked.
Urethral Calculi
The detection of Urethral Calculi is, at present, too sensitive. So, the AI will sometimes “see” these when they are not present. We are working to correct this.