MITI using pattern recognition software was successfully used to differentiate between thermographic patterns of CKCS dogs with CLM and SM vs. those without SM. We found MITI using pattern recognition software was 70% accurate in correctly identifying CKCS dogs with CLM and SM with an 81% sensitivity and 58% specificity. As such, these results reaffirm the view of MITI as a screening tool rather than a diagnostic tool given the high sensitivity and relatively low specificity. Additional studies are being conducted with different mask sizes (region of interest, as defined in methods section) and histogram features to see if better improvements in sensitivity and specificity can be made. By reducing the mask size (i.e., eliminating muzzles, ears, etc.), the background data or “noise” (artifact) can be reduced thus concentrating the more relevant data and potentially allowing for improved feature identification. Larger data sets including normal are being acquired, as this information will enhance the accuracy of the normal masks making comparisons more distinguishable.
MITI may be helpful clinically for clients who decline advanced diagnostic imaging due to financial concerns, patient anesthetic risk concerns or other reasons. MITI might provide further insight for these non-surgical candidates and aid in appropriate, goal-directed therapy.
The diagnosis of CLM can only be made by MRI, which is also the preferred imaging modality for diagnosing SM. There has been some acceptance in the veterinary community of the use of “abbreviated” MRI studies utilizing views of the head and neck region with implementation of limited imaging sequences in an effort to reduce costs. SM has been reported to be most commonly located at the C1-4 and T2-L2 spinal cord segments in a prior study . MITI could be used as a screening tool to further support the necessity of full spinal imaging.
Historically, a goal of MITI has been to identify changes associated with pathology prior to clinical signs [22-24]. With further improvements in sensitivity, MITI has potential to be offered as a low-cost screening tool for breeders in young patients. Young patients can be imaged easily for the development of syringomyelia in patients without clinical signs, with continued monitoring as growth occurs. MITI might aid in determining CKCS breed reproduction standards and sales of healthy offspring in the future. Further investigation with regards to MITI in young CKCS dogs is needed.
Treatment options for CLM/SM involve surgical or medical management. The preferred method of treating humans with CLM/SM is surgical decompression via a procedure called foramen magnum decompression (FMD) [25-27]. The authors have reported surgical success in veterinary patients as well, with a FMD combined cranioplasty procedure that was able to improve or resolve clinical signs in approximately 80% of dogs [28, 29]. Further studies are on going to evaluate for syrinx resolution in these post-operative patients. Currently, the only method of reassessing syrinx status after surgery is to repeat a full spinal MRI. MITI could potentially be used as a screening for syringomyelia resolution in post-operative FMD patients. Further development of computer recognition pattern analysis to improve both sensitivity and specificity would be necessary.
This study revealed that MITI is a successful screening test for the presence of SM in CKCS with CLM. Compared to other imaging modalities, MITI is a quick, inexpensive modality that does not require sedation nor anesthesia, and eliminates radiation exposure (to patient & staff). MITI does not provide insight to syrinx location or severity nor should it be used as a sole diagnostic modality. While veterinary thermographic imaging continues to improve as advances in technology occur, MRI will remain the gold standard for definitive diagnosis and staging of Chiari-like malformation and syringomyelia.
Limitations of this study include the moderate sample/population size, limited number of thermographic views obtained, and only one disease process (CLM) presence.
In this study, dorsal craniocervical views were chosen based on a pilot study utilizing four views (front of head, top of head, left side of head, right side of head) that revealed that the top of the head view provided the best success rate (unpublished author data). Secondly, the top of the head view includes the craniocervical junction most appropriately compared to other views. Imaging of this region was important, as it has been shown that CSF obstruction at the foramen magnum causes turbulent flow that is associated with SM presence and severity . It was, and still is, believed that this turbulent flow at the foramen magnum accounts for changes noted in our thermographic patterns seen with syringomyelia presence. Ongoing studies are currently investigating spinal thermographic imaging (dorsal full spinal views) in an attempt to improve overall success rate for SM identification in the CKCS.
All included dogs were diagnosed with CLM via MRI and excluded if other abnormalities or disease processes were detected. Given this study design, it is not known whether it is possible for MITI to distinguish SM from other cervical pathologies without MRI confirmation. In future studies, it would be useful to image patients with other pathologies as well as absence of pathology for control purposes. Despite all dogs having an MRI confirmed diagnosis of CLM, these dogs were not further divided into different categories based on their CLM disease. Divided categories could include CLM compression severity (mild, moderate, severe), or craniocervical compression types (medullary kinking, dorsal compression, etc.) .
Future studies based on larger populations, data sets (including normal and other pathologies), and mask sizes may help further improve pattern recognition software success.
It is worth noting that although MITI is not readily available in all veterinary clinics, its growing popularity has made obtaining the necessary equipment more feasible for most practices. Compared to other diagnostic imaging modalities, MITI requires significantly less equipment and minimal space occupancy. Computer software packages for image processing are readily available to all.