Cath Lab Digest

Given recent technological advances with vascular imaging modalities, successful limb salvage may be an option for patients previously resigned to amputation. This author details how various imaging options, including multi-channel computerized tomography angiography, can be beneficial for high-risk podiatric patients.

   Primary amputations still occur worldwide at an alarming rate. Worldwide, it is estimated that there is a diabetic foot amputation every 30 seconds.¹

   Therefore, an opportunity exists with the contemporary non-invasive vascular imaging to better identify the vascular and chronic limb ischemia (CLI) patient who would be a candidate for limb salvage revascularization and make an impact on the high incidence of primary amputation.

   In a recent analysis of 417 CLI patients in the United States, 67 percent had a primary amputation as their initial CLI treatment and only 49 percent had any diagnostic vascular evaluation. Of those, only 34 percent underwent an ankle-brachial index (ABI) study and 16 percent had angiography.²

   There have been recent improvements in noninvasive vascular imaging including magnetic resonance angiography (MRA), multi-channel computerized tomography angiography (CTA) and the safety of traditional angiography. Given all those improvements, I believe no CLI patient should be scheduled for an amputation without at least noninvasive vascular imaging and preferably limb salvage angiography beforehand.

   Indeed, the healthcare industry’s next challenge should be to change this “pathway to amputation” to a “pathway of revascularization,” especially with the dramatic improvement in infrapopliteal diagnostic and treatment options over the last three to four years.

What You Should Know About Multidetector CTA

   Conventional diagnostic angiography (CDA) and digital subtraction angiography (DSA) remain the clinical “gold standards” for vascular imaging but both have multiple limitations. Foremost among these limitations are the invasive nature of the procedures with the attendant morbidity associated with catheterization.

   Physicians have advocated the use of MRA to address the limitations of DSA but MRA also possesses significant limitations, notably limited temporal and spatial resolution. Magnetic resonance angiography has also recently been associated with renal failure and systemic nephrogenic sclerosis, is very expensive and is not widely available.³

   Multidetector CTA is an emerging, non-invasive modality, which enables one to assess vasculature including coronary artery anatomy. In comparison to conventional angiography or DSA, multi-detector CTA is less expensive, less invasive and faster. The technology requires fewer medical professionals and potentially reduces radiation exposure and contrast use. Other advantages of CTA include the ability to view vessels in multiple tomographic planes and create 3-D reconstructions.

   Since computerized tomography angiography techniques were originally described in 1992, CT scanners have advanced from single-detector systems to powerful multi-detector systems capable of rapidly acquiring 16 to 64 channels of data with higher spatial resolution. Current multidetector CT scanners obtain very high-resolution images and allow coverage of more than 120 cm with a single scan. The multidetector CT now permits scan times of less than a second, scan thickness of less than 1 mm and the acquisition of more than 4,000 images per examination with a single venous injection.