Color Doppler Evaluation of the Pedal Arteries as a Predictive Tool in Peripheral Arterial Disease
- Volume 8 - Issue 10 - October 2011
- Posted on: 10/5/11
- 0 Comments
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George Koshy Chiramel, MD, Koyeli M. Mahata, MD, Shyamkumar N. Keshava, DNB, FRCR, FRANZCR
Background. Early diagnosis of peripheral arterial disease (PAD) is important. Screening tests like pulse palpation and ankle-brachial pressure index (ABPI) measurement have varying levels of objectivity, accuracy, and reproducibility. Objective. To evaluate the ability of color Doppler study of the dorsalis pedis (DP) and posterior tibial (PT) arteries to predict the presence of significant PAD in that limb. Methods. This was a cross-sectional study done in a tertiary hospital, which involved patients who had undergone color Doppler studies of the lower limbs during a 6-month period. Color Doppler study images of the DP and PT arteries were arranged in a random manner and independently evaluated by 2 investigators who were unaware of the status of PAD in these limbs. Each investigator evaluated the images for peak systolic velocity and waveform pattern, trying to predict the possibility of PAD in that limb. Results. The 2 investigators showed excellent agreement in predicting PAD, which was slightly better with PT (92.31%) than with DP (90.57%). The first investigator showed a higher sensitivity while the second investigator showed a higher specificity in the prediction of PAD. Both investigators showed excellent agreement regarding the waveform pattern in the DP and PT arteries, which was 86.8% and 82.7%, respectively. Conclusion. Color Doppler evaluation of the pedal arteries could be a good screening tool for PAD and could have some potential to replace other screening tests. Further evaluation of this tool is required in a large-scale community-based setting.
VASCULAR DISEASE MANAGEMENT 2011;8(10):E172–E174
Key words: predicting significant PAD, color Doppler, pedal arteries, peripheral arterial disease
Peripheral arterial disease (PAD) involving the lower limbs is seen in 3–10% of the population and can be even higher (up to 15–20%) in people aged over 70 years.1 Most people are asymptomatic. However, intermittent claudication is common and can progress to develop severe symptoms in acute or chronic critical limb ischemia (CLI). PAD is a common cause of lower limb amputation and can significantly impair the quality of life, making its early identification very important.
This study was performed to evaluate the ability of the color Doppler study of the dorsalis pedis (DP) and posterior tibial (PT) arteries to predict the presence of significant PAD in that limb.
Materials and methods
This cross-sectional study was done in a tertiary level hospital. The institutional ethics committee had given their approval for the study. Patients who had undergone a complete color Doppler evaluation of the arteries of the lower limbs (either unilateral or bilateral) for suspected PAD over a 6-month period were included in the study. Cases were excluded if the documentation was incomplete, if the color Doppler images of the dorsalis pedis artery (DPA) or the posterior tibial artery (PTA) were unavailable on the picture archival and communication system (PACS), or if there was a previous history of vascular surgery or endovascular treatment for the limb.
The color Doppler evaluation of the patients had been done earlier as per the usual protocol by experienced radiologists. The DPA on the dorsum of the foot and the PTA at the level of the ankle had been examined at rest. Grey scale images and waveform patterns had been documented to demonstrate each artery and the blood flow within.
The color Doppler report was used as the reference standard to characterize each leg as having PAD or not. PAD was considered present if there was any stenotic or occlusive lesion involving the arteries, whether hemodynamically significant (> 50%) or not (< 50%), irrespective of the number of lesions.
Each color Doppler image was demonstrated as a picture slide of either the DPA or the PTA showing the waveform pattern and mentioning the name of the artery (Figure 1). All patient identifiers were removed and each slide was given a code number. These slides were then rearranged in a randomized manner using a computer generated randomization sequence and sent as an email attachment to 2 consultant radiologists for independent evaluation. The initial investigator who collected, rearranged, and sent the images was the only person having knowledge of the patient data and the status of PAD in each image. The other 2 investigators were unaware of the patient data and interpreted the images independently. After describing the waveform pattern (mono, bi, or triphasic) in each slide, they stated whether they felt that that limb had PAD or not. The impressions of the investigators were collected and analyzed to calculate the ability of pedal artery Doppler to predict PAD. The agreement between the investigators was also calculated.
The measures of diagnostic accuracy (sensitivity, specificity, positive and negative predictive values) were calculated to evaluate the ability of pedal artery color Doppler to detect PAD. The inter-investigator agreement was calculated using the kappa statistic, which corrects for chance.2 This was interpreted depending on the kappa value: poor (kappa = 0 to 0.25), moderate (0.25 to 0.5), good (0.5 to 0.75), and excellent (0.75 to 1). All data analysis was done using STATA 10.0 (StataCorp LP, College Station, Texas).