Research study authors: Fendrik K, Biró K, Endrei D, Koltai K, Sándor B, Tóth K, Késmárky G. The authors come from the University of Pécs Medical School, Hungary.
You can take a look at the study here.
The aim of the study was to establish how automated 4-limb blood pressure monitors with TBI measurements could contribute to PAD screening. While automated measurements of the Ankle-Brachial Index are well-established in this domain, TBI measurements are underemphasised.
In the study, the ABI measurements were obtained by means of manual Doppler and the MESI mTABLET ABI. The Toe-Brachial Index measurements were obtained with a laser Doppler fluxmeter and photoplethysmography (with MESI mTABLET TBI and another device).
There was a strong, significant correlation between the MESI mTABLET ABI and Doppler, with a non-significant mean difference of -0.068. In the testing of the MESI mTABLET TBI, another photoplethysmographic device and the laser Doppler fluxmeter, no significant differences were established between the three devices. The specificity and sensitivity were equivalent. 
One of the advantages of the MESI mTABLET diagnostic system pointed out in the study was the combination of ABI and TBI on one device. The combination of the MESI mTABLET ABI and the MESI mTABLET TBI measurements discovered 92.4% of limbs with PAD as diagnosed by imaging techniques. 
In this blog you will learn:
Peripheral Arterial Disease (PAD) is the third most frequent cause of atherosclerotic mortality, only superseded by heart disease and stroke. Despite its frequency, it often remains undetected; its typical symptom, intermittent claudication, is often mistaken for musculoskeletal problems, especially in elderly patients.
The established non-invasive test for PAD discovery is the Doppler-assisted measurement of the Ankle-Brachial Index, but the use of this technology as it is time-consuming and requires expertise. As an answer to this problem, automated oscillometric ABI-measuring devices have been developed, showing acceptable feasibility and diagnostic accuracy  . Due to their easy use and examination speed, they are particularly useful for mass PAD screenings  .
For cases of incompressible arteries (connected with advanced age, diabetes, chronic kidney disease and other factors), automated Toe-Brachial Index measurement has been developed. Despite its clinical importance, however, it is underused as a PAD screening method. 
The study used the MESI mTABLET diagnostic system as a wireless, automated device that combines oscillometric ABI measurements and PPG TBI measurements. In testing the diagnostic accuracy of the MESI mTABLET ABI and the MESI mTABLET TBI, vascular imaging techniques were used as a reference. The MESI mTABLET TBI was compared to the laser Doppler method and another PPG device. The efficacy was contrasted in diabetic and non-diabetic patients.
The aim of the study was to analyse how the MESI mTABLET device can contribute to PAD screening. 
The ABI was checked in 233 lower limbs of 177 patients. The MESI mTABLET ABI showed numerical ABI results in 210 cases. In the remaining 23 cases, MESI mTABLET ABI showed a text warning on the possibility of severe PAD. When compared to vascular imaging, it showed that 100% of these cases presented a PAD lesion. This points out to high accuracy of the MESI device.
The MESI mTABLET ABI was strongly correlated with manual Doppler results, with a Pearson coefficient of correlation of 0.672 (p < 0.001) in all subjects, and r = 0.744 (p < 0.001) in non-diabetic and 0.562 (p < 0.001) in diabetic patients. The mean difference between MESI mTABLET ABI and Doppler measurements was -0.068.
When compared to imaging diagnosis, the optimal cut-off value for MESI mTABLET ABI determination was 0.99.
The MESI mTABLET TBI measurement results were compared to those of laser Doppler and another PPG device. No significant difference between the results of the three measurement techniques was established. The specificity and sensitivity were excellent and equivalent regardless of the technique.
The study tested how many of 79 legs of the 44 PAD patients (which was pre-known or newly diagnosed) would be recognised with different measurement techniques. The Doppler result showed pathological results in 56 limbs (70.9%) and the MESI mTABLET ABI in 45 limbs (57.0%) either with text warning or numerical data, with ABI cut-off level of 0.9. When the cut-off level was 1.0, the MESI mTABLET ABI diagnosed 59 limbs (74.7%). The use of a combination of the MESI mTABLET ABI and TBI, raised the diagnostic result to 73 of the 79 diseased limbs.
The MESI mTABLET ABI showed excellent results in comparison to manual Doppler in detecting PAD. The MESI mTABLET TBI, in turn, proved equivalent to other devices available on the market. Used in combination, the MESI mTABLET ABI and TBI managed to identify nearly all preknown/newly diagnosed PAD patients (42 out of 44, which is 95,5%).
The study concludes: “Since the MESI mTablet unites the ABI and TBI measurements in one, easily operated device, the possibility of sequential measurements could facilitate more widespread use.”