Diagnostic Accuracy of Color Doppler Imaging in the Evaluation of Peripheral Arterial Disease
- Volume 6 - Issue 1 - Jan/Feb 2009
- Posted on: 1/14/09
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As Compared to Digital Subtraction Angiography
1Chiramel George Koshy, MD, 1Binita R. Chacko, MD, 1Shyamkumar N. Keshava, DNB, FRCR, FRANZCR, 2Sunil Agarwal, MS
From the 1Departments of Radiology and 2Vascular Surgery, Christian Medical College, Vellore, Tamil Nadu, India.
Correspondence: Dr. Chiramel George Koshy, Department of Radiology, Christian Medical College, Vellore, Tamil Nadu, India 632004. E-mail: [email protected].
Manuscript submitted November 12, 2008, provisional acceptance given December 5, 2008, accepted December 11, 2008.
Disclosure: The authors report no financial relationships or conflicts of interest regarding the content herein.
Purpose. To estimate the diagnostic accuracy of color Doppler imaging compared to digital subtraction angiography (DSA) in the assessment of patients with peripheral arterial disease (PAD). Methods and materials. Patients with a clinical diagnosis of lower limb PAD who were awaiting diagnostic DSA first underwent a color Doppler scan. The subsequent DSA was done by another radiologist unaware of the Doppler findings. Results were recorded on separate proforma. Statistical analysis. The evaluated segments were graded as normal, insignificant disease (< 50%), hemodynamically significant stenosis (>/= 50%), and occlusion. The results were analyzed using two-way tables and the kappa statistic to look for concordance between the two modalities. Results. The study involved 41 patients and analyzed 720 arterial segments. Excellent concordance (1.0) was seen in the aortoiliac segments. Good concordance was seen in the common and external iliac segments (0.96–0.77), as well as in the common and superficial femoral segments (0.77–0.88). The popliteal segments showed lower concordance (0.66). There was only fair concordance (0.54–0.67) in the infrapopliteal segments, with relatively better results in the posterior tibial artery. The overall sensitivity ranged from 69–100%, specificity 69–100%, PPV 92–100%, and NPV from 70–100%, depending on the vascular segment evaluated. Conclusions. For identifying hemodynamically significant lesions, color Doppler was found to be as good as DSA in the aortoiliac and femoropopliteal regions. However, DSA is still required to evaluate the infrapopliteal segments.
Peripheral arterial disease (PAD) is a common problem faced by clinicians. Reduction of blood supply to a lower limb initially presents as intermittent claudication, while further restriction of flow leads to ischemic pain at rest. If not treated, trophic changes like ulceration and gangrene may occur and can result in loss of the limb. Diagnostic imaging is performed when PAD limits the patient’s lifestyle. Accurate characterization of the number, level, and severity of lesions is necessary to plan treatment. The imaging modality should provide adequate information and minimize risk and inconvenience to the patient. Most centers use color Doppler as the initial imaging modality, sometimes followed up with digital subtraction angiography (DSA).
Color Doppler versus DSA. Color Doppler imaging is a well-established modality in the assessment of PAD. It is safe, painless, noninvasive, reproducible, relatively inexpensive, and widely available as an outpatient service. It uses no ionizing radiation or contrast material. However, it is time consuming and does not provide an image of the arterial tree that can be easily visualized by the clinician. Moreover, the time taken for the study as well as its accuracy depend on the expertise of the sonologist.
DSA is reproducible, provides an easily visualized image of the arterial tree, can measure pressure gradients, and can be used for interventional treatment. However, this requires hospital admission and has risks associated with vascular access and catheterization. It involves the use of ionizing radiation and iodinated contrast agents. Because of its invasive nature and high cost, it is not suitable for screening or for follow-up purposes. Although it is considered to have a high level of objectivity, there can be considerable interobserver variation in interpretation.1–4
While angiography is a morphological study and provides information only about the vessel lumen, color Doppler imaging is both a morphological and functional study, providing information not only about the vessel wall but also hemodynamic information.
Recent advances like better post-processing capability, transducer technology, image resolution, signal strength, and spectral analysis capabilities have improved the ability of color Doppler to visualize and grade abnormalities, thus extending the scope for non-invasive assessment of PAD.
Angiography has been considered by many as the definitive investigation in the evaluation of PAD. Many comparative studies have considered color Doppler to be inferior to angiography.
However, a few studies have found that color Doppler could replace up to 97% of diagnostic arteriography of the lower limb5 and could safely and accurately guide therapeutic vascular interventions,6 thus suggesting that DSA no longer be regarded as the gold standard.
Materials and Methods
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