Fig. 14.1
Patient with longstanding RP and SSc and no atherosclerotic risk factors. She presented with dry gangrene of multiple toes and no palpable pedal pulses. Angiography showed severe tibial occlusive disease more typical of atherosclerotic disease
Fig. 14.2
Patient with longstanding RP and SSc. She presented with dry gangrene of multiple toes and no palpable pedal pulses. Shown are classic angiographic appearance of non-atherosclerotic vasculopathy with normal medium sized vessels that abruptly occlude near the ankle. The small vessels that remain patent appear normal
Table 14.1
Comparison of various methods of angiography
Advantages | Disadvantages | |
|---|---|---|
Conventional X-ray | Standard method for viewing lumen of vessels: stenosis, occlusions, aneurysms, and other irregularities | • Requires intra-arterial puncture: bleeding, aneurysm, occlusion • Risk of ionizing radiation exposure • Contrast exposure: potential nephrotoxicity |
MR angiography | • No intra-arterial puncture • Images lumen and vessel wall: detection of wall inflammation • No ionizing radiation exposure | • Long-time to perform • Exposure to gadolinium • Cannot use with devices: pacemaker, metal implants |
CT angiogram | • No intra-arterial puncture • Rapid performance • Allows three-dimensional imaging of vessels and surrounding structures • Images lumen and vessel wall: thickening, calcifications, aneurysms | • Risk of ionizing radiation • Intravenous contrast: nephrotoxicity |
Assessment by angiography should be used selectively for severe cases. Generally it should be used as a preoperative planning tool as the presence of a lesion should already be known from noninvasive testing. For example, patients with SSc and severe RP characterized by refractory digital ulcerations despite medical therapy have been investigated for large artery involvement to help define therapy. In a retrospective series of 15 patients, ulnar artery occlusive disease was documented by a positive Allen test and ulnar artery angiography. Ulnar artery revascularization combined with digital sympathectomy was done in 8/15; all 8 experienced dramatic improvement in RP and healing of digital ulcers [9]. Although uncontrolled, this study in a selected subgroup of SSc who were failing conventional therapy, suggests that if ulnar artery disease is suspected by noninvasive testing then confirmed by angiography, patients can be helped by revascularization. A proposed classification of the various arterial lesions observed by angiography in patients with SSc and severe RP has been published. Although unvalidated by a prospective study, this survey suggests that patients can be stratified as follows: type I and II involve the radial or ulnar arteries. (Type I with complete occlusion, while type II involved partial occlusion); Type IIIa showed tortuous, narrowed, or stenosed common digital and digital vessels and Type IIIb is a subset which involved the digital vessel of the index finger related to exposure to prolonged vibration; Type IV and V showed global involvement from the main to digital vessels (Type IV showed diffused tortuosity, narrowing and stenosis and Type V is the most severe type with paucity of vessels and very scant flow) [10]. This classification may be helpful when making surgical decisions (see Chap. 22). In fact, the main advantage of standard digital subtraction angiography is the ability to endovascularly treat many stenoses or occlusions at the time of the diagnostic test.
Magnetic Resonance Angiography
Recently, MRA has been used with and without contrast material as a safe, reliable, and accurate technique for evaluation of vascular pathologies of the hand. MRA has a major advantage over arteriography in that it is a noninvasive examination and image quality is comparable to that of conventional angiography without risk of induced vasospasm. MRA also does not require the use of ionizing radiation, and the contrast agent used, if any, is not nephrotoxic. However, contrast-enhanced MRI techniques should be avoided in patients with renal insufficiency or patients who require hemodialysis due to the risk of nephrogenic systemic fibrosis, a debilitating and potentially fatal condition. This technique can also be used for repeated examinations allowing sequential comparisons. However, MRA studies have been done in a limited number of unselected cases and not consistently in the context of critical digital ischemia; thus digital subtraction angiography is still recommended as the goal standard when evaluation is needed for diagnosis or before corrective vascular surgery.
Non-contrast MRA of the hand has also been performed; however, current experience is limited to a few specialized centers and these techniques are not widely available [11–13]. Non-contrast techniques also have the disadvantage of longer imaging time than standard contrast-enhanced techniques, which can lead to motion degradation of images in subjects that have difficulty lying still. Contrast-enhanced MR angiography offers the ability to acquire time-resolved images that also can show blood flow dynamics [14]. High-resolution is needed to visualize the small arteries of the fingers which are often less than 1 mm in diameter. The limitations of MRA are its cost, its availability, the limited depiction of small vessels beyond major digital arteries, and venous contamination; MRA may also overestimate the degree of vessel stenosis particularly at the origin of small vessels. Hand vessel visualization can be limited in the cold environment of the MRI suite and previous studies have shown that hand warming may improve vessel visualization, even among normal volunteers [13]. Lastly, the quality of the information gained from an MRA is dependent on the quality of the magnet generating the images and the experience of the radiologist reading the images.
Magnetic Resonance Angiography (MRA) Studies in Scleroderma
There have been several studies in patients with SSc that illustrate the potential usefulness of MRA studies in patients with RP and its complications. However, these studies were not referenced to digital subtraction angiography limiting firm conclusions. MRA was used to study the digital vasculature in patients with SSc by using the hand with a phased array wrist coil [15]. The MRA protocol consisted of four successive acquisitions, each lasting 52 s, of three-dimensional coronal cross-sectional images after gadolinium injection. The primary evaluation used a predefined criteria for the second to fifth fingers. The primary criteria were distality and quality of arterial opacification, avascular areas, and venous return. The time sequences are shown in Fig. 14.3. In a series of 38 consecutive and unselected SSc patients, 35 (92 %) patients had at least one true digital artery which did not reach the first phalanx, as assessed at the initial arterial analysis and 23 (61 %) had four or more damaged arteries. Twenty-eight (74 %) patients had thin arteries and 23 (61 %) had more than one avascular area. Current digital ulcers were substantially more frequent among SSc patients with more than four proper digital arteries which did not reach the first phalanx than other patients (10/23 vs. 0/15; p = 0.003). All the patients had abnormal venous flux and general venous blockage was found in 12 patients (32 %) [15]. The main findings of this study are the substantial arterial and venous damage detected by MRA in patients with SSc (see Figs. 14.4, 14.5, 14.6, and 14.7). This study emphasizes that both the microcirculation and also small caliber vessels are involved in SSc as also shown by previous studies using conventional x-ray angiography.
