Is the New Standard of Care for Optimal Venous Imaging Duplex Ultrasound and Infrared Thermography

FOR THE PAST 50 years, the use of Duplex ultrasound (DUS) as an imaging tool for lower extremity venous disease has remained the most common and widely preferred methodology for diagnosing Chronic Venous Insufficiency (CVI)1

Early diagnosis for CVI is essential but remains challenging. As no true screening modality currently is in widespread use, the clinician is often dependent on patient reporting of early symptoms unless certain visual clues are observed during careful physical examination.

Unfortunately, as CVI inevitably progresses, the correlation between CVI’s morbidity and all-cause mortality increases by 3-fold.2

Having an early detection screening tool seems essential in assisting our clinicians in addressing CVI, one of the most prevalent vascular diseases. Due to the high prevalence of CVI in today’s populations, an effective screening and mapping adjunct to DUS would make a big impact in what is still considered a vastly underserved disease process as the vast majority of CVI cases remain undetected.

As discussed in previous literature, the performance of the DUS is highly dependent on the education and skill of the trained technician as well as the individual patient’s (often variable) symptom communication to clinicians. Main indications for performing a leg duplex ultrasound are often related to concerns such as claudication symptoms, non-healing ulcers, absent or faint distal pulses, and skin discolor-ation3, leaving many common symptoms such as leg swelling, cramping, and other concerns affecting activities of daily life often not investigated. Furthermore, the main guidelines for the performance of venous duplex ultrasound typically fall within visual CEAP categories 3-64 with no formal screening tool available for consistent recognition when visual cues are absent which occurs a significant portion of the time. This makes CVI one of the only major prevalent disease categories without a widely accepted screening tool.

Recently, thermal imaging has gained awareness through its use of body temperature measurement for the detection of fever related to COVID-19. In the case of CVI, Point of Care Infrared Thermal Imaging (POCIT) has also been shown to have the ability to effectively map temperature pattern changes with a difference of as low as 0.058˚F in the lower extremities. When those specific heat patterns are recognized and compared to the gold standard, duplex ultrasound (DUS), POCIT has recently been published to have a sensitivity of 98% and specificity of 100%.5 The reason for this high correlation between warmer heat patterns on the surface of the legs and its high correlation with refluxing veins is thought to be due to “hotter” core blood pathologically flowing from the deeper venous system to the superficial veins.

To further corroborate our suggestion that POCIT imaging should be added to screening and mapping protocols for CVI, a recent peer-reviewed published study showed that an average of 24.6% clinically rele- vant refluxing vessels (confirmed by DUS) were found when POCIT was used adjunctively with DUS.6 Another recent clinical study that included 12,423 individuals that underwent venous ultrasound, those with detected CVI has as high as a 68% greater risk of all-cause death.2 Thus, the value of POCIT imaging with adjunctive DUS not only will help with better screening and mapping but could have a larger impact on the health of our patients overall.

This POCIT novel technology has recently provided what many believe is “game-changing” data, suggest- ing that it is clinically essential for use in DUS in the early detection and diagnosis of CVI. Just like we have commonly utilized Ambulatory Blood Pressure and Arterial Brachial Index for screening arterial disease, so might POCIT begin an even better era in the diagnosis of CVI. The recent FDA Clearance for ThermPixTM (novel POCIT medical device) with a broad indication in human use, suggests we are at the beginning of an exciting opportunity to more effectively understand the relative heat patterns of disease. V