Imaging of aortic aneurysms and dissection: CT and MRI.

There are numerous approaches to the diagnosis of aortic aneurysms and aortic dissection. Echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) have enthusiastic proponents promoting each technique, which to some extent obscures the real value of each technique. This review examines the role of these techniques in the diagnosis of aortic disease, with special reference to the most recent published literature and an emphasis on the use of CT and MRI. For most patients with chronic aortic disease, MRI is the most appropriate investigation. In acute situations, CT scanning is usually the most useful technique, with echocardiography added for those with ascending aortic disease or cardiac complications.

MRI changes in myocarditis--evaluation with spin echo, cine MR angiography and contrast enhanced spin echo imaging.

AIM: Myocarditis is probably under-diagnosed with clinical criteria generally used for diagnosis. Magnetic resonance imaging (MRI) has shown promise in detecting heart muscle disorders and we set out to assess the role of cine magnetic resonance angiography (MRA) and contrast enhancement in myocarditis, as there is a need for a non-invasive tool that can aid prognosis and follow-up. MATERIALS AND METHODS: Twenty patients were evaluated with T1 SE pre- and post-gadolinium enhancement and cine MRA. Four patients were histologically proven to have myocarditis, eight others were diagnosed as having myocarditis by clinical criteria and eight did not have myocarditis. Images were evaluated in a blinded fashion for regional wall motion abnormality and contrast enhancement pattern. Analysis of contrast enhancement by signal intensity measurement was also performed. RESULTS: Focal myocardial enhancement with associated regional wall motion abnormality correlated with myocarditis in 10 out of 12 patients, two patients with abnormal focal enhancement alone also clinically had myocarditis. None of the non-myocarditis patients showed abnormal focal enhancement. Enhancement analysis suggests that focal corrected myocardial enhancement of > 40% is abnormal. CONCLUSION: In the correct clinical context, focal myocardial enhancement on spin echo MRI strongly supports a diagnosis of myocarditis, especially when associated with regional wall motion abnormality.Roditi, G. H. (2000). Clinical Radiology55, 752-758.

Imaging in blood stasis. The role of imaging techniques in defining the causes, presence, and effects of blood stasis.

There have been considerable developments in the ability to image blood vessels and blood flow using ultrasound, CT, and MR imaging. The effects of vascular pathology in causing changes in the blood leading to thrombus formation now can be seen clearly because of these developments. In particular, new ultrasound MR imaging techniques allow more precise assessment of vessel walls and flow than has ever been possible before using conventional techniques, such as angiography. MR imaging has a unique potential for noninvasively demonstrating the natural history of developing vascular disease and the effects of this on blood flow and progression to thrombosis.

Optimized diagnostic angiography in high-risk patients with severe peripheral vascular disease.

Conventional arteriography remains the usual method for preoperative assessment of severe peripheral vascular disease (PVD). Unfortunately, many peripheral arteriograms are still performed with a suboptimal technique, which can cause significant diagnostic errors in patients with severe PVD. A suboptimal technique may be due to poor collimation (causing incorrect exposure and incorrect gray scale), excessive patient-film distance (magnification unsharpness), inadequate volume or density of contrast material, poor contrast resolution (screen-film arteriography), nonselective injection, patient movement, and pressure from restraints or incorrect patient position (failure to profile lesions, pseudo-occlusion from external pressure or plantar flexion). The technique of selective digital subtraction arteriography (DSA) allows one to avoid these errors. The superior contrast resolution of DSA allows use of lower concentrations of contrast material. Selective injection into the external iliac artery allows proper positioning and improves image quality. Demonstration of distal vessels is best achieved by using biplane arteriography. For patients with severe resting ischemia, especially those with diabetes, high-quality selective DSA is essential to ensure that all distal vessels suitable for distal bypass grafting are identified. When properly performed, selective DSA remains the investigation of choice for reliably demonstrating arterial anatomy in high-risk patients with severe PVD.

Breathhold cardiac MRI and MRA.

Recent developments in MRI software and hardware have increased the speed and versatility of cardiac MRI by allowing image acquisition in a single breathhold. Many studies have shown that conventional cardiac MRI is as accurate as echocardiography or cardiac catheterization for diagnosing numerous cardiac conditions. In many cases cardiac MRI is the most accurate diagnostic technique but has not been widely adopted for routine cardiac imaging. One reason why the use of cardiac MRI has been limited is the long examination times required for conventional cardiac MRI. The development of better hardware, such as faster gradient amplifiers and dedicated surface coils, has allowed the implementation of much faster EKG-gated imaging sequences. These can be used in a single breathhold period, with a significant improvement in image quality compared with conventional sequences. Breathhold sequences can provide all the information provided by conventional cardiac MRI in a shorter time and with equal or better accuracy. Breathhold imaging will allow much wider application of MRI to routine cardiac diagnosis.

Hepatic chemoembolization: effect of intraarterial lidocaine on pain and postprocedure recovery.

PURPOSE: To determine if intraarterial lidocaine reduces pain during and after chemoembolization, and whether it influences postprocedure recovery. METHODS: Two patient cohorts undergoing selective hepatic chemoembolization were compared. Chemoembolization was performed without lidocaine (control group) in 27 patients and intraarterial lidocaine was used (lidocaine group) in 29 similar patients. Objective changes in patient management were assessed. Pain reduction in 31 more procedures with lidocaine (total 60) was assessed and related to tumor type. RESULTS: During chemoembolization, intraarterial lidocaine reduced the need for additional intravenous analgesics from 69% to 19%. After chemoembolization the mean Dilaudid dose in the first 24 hr was reduced from 9.5 mg to 4.15 mg; accordingly, the mean length of hospital stay was reduced from 67.5 to 53.5 hr. During the day of chemoembolization, the mean oral fluid intake increased from 420 ml (control group) to 487 ml (lidocaine group); the percentage of patients taking solid food on the day of chemoembolization increased from 3% to 43%. CONCLUSION: Intraarterial lidocaine during chemoembolization reduces the severity and duration of pain after chemoembolization resulting in faster recovery thus reducing the length of hospitalization.

Diabetic versus nondiabetic limb-threatening ischemia: outcome of percutaneous iliac intervention.

OBJECTIVE: The purpose of this study was to compare the effectiveness of iliac angioplasty and outcomes in diabetic patients and nondiabetic patients with limb-threatening ischemia. MATERIALS AND METHODS: Records of 91 consecutive patients with limb-threatening ischemia (rest pain, nonhealing ulceration, or gangrene) who, during a 6-year period, underwent iliac angioplasty of hemodynamically significant lesions were reviewed. Stents were placed in patients with suboptimal findings at angioplasty. Sixty-eight (75%) of the 91 patients were diabetic. Life table analysis and log-rank significance tests were used to compare rates of primary iliac artery patency, primary and secondary graft patency, limb salvage, and survival in diabetic patients versus nondiabetic patients. RESULTS: One hundred seven iliac lesions were treated with percutaneous angioplasty. Ten iliac stents were placed because of suboptimal results at angioplasty. The mean time of follow-up was 20 months (range, 2-62 months). Sixty-eight patients (75%) underwent peripheral reconstruction. Outcomes were comparable in both patient groups for primary iliac patencies at 4 years (diabetic patients, 85%; nondiabetic patients, 76%; p = .5), primary and secondary graft patencies at 4 years (diabetic patients, 65% and 73%, respectively; nondiabetic patients, 74% and 100%, respectively; p = .7 and .19, respectively), 4-year limb-salvage rates (diabetic patients, 93%; nondiabetic patients, 79%; p = .07). Major complications of angioplasty occurred in four patients (4.4%). CONCLUSION: Outcomes of iliac angioplasty and limb-salvage rates were comparable for diabetic patients and nondiabetic patients who underwent current methods of iliac angioplasty and infrainguinal reconstruction.

Chemoembolization of hepatic neoplasms: safety, complications, and when to worry.

Chemoembolization of the liver for unresectable malignancy, although controversial, is being used with increasing frequency. Chemoembolization can be difficult, and there is great potential for causing complications. There are also findings after chemoembolization, particularly on computed tomographic scans, that may appear to indicate complications but are common and of no concern. Chemoembolization requires an understanding of the congenital and acquired variations of arterial anatomy that may be seen supplying the liver. Assessment of the patency of the portal vein is also required. An abnormal portal vein demands significant changes in technique to allow safe chemoembolization. Partial or complete occlusion of the portal vein is associated with significantly decreased survival but does not prevent a worthwhile response to chemoembolization and is not an absolute contraindication. The presence of chemoembolization material in the gallbladder is not uncommon; with the technique used by the authors, the chemoembolization material infrequently causes cholecystitis or gallbladder infarction. Extrahepatic chemoembolization material is commonly seen in other organs but usually does not cause problems, presumably because the dose deposited outside the liver is small compared with the dose delivered to the liver. Other complications include pseudocirrhosis, liver infarction and abscess formation, carcinoid crisis, hepatorenal syndrome, and liver rupture.

New developments in cardiac magnetic resonance imaging.

Technical developments have increased the speed and versatility of cardiac magnetic resonance imaging (MRI). Numerous studies show that cardiac MRI is as accurate as more conventional alternatives for diagnosis of many cardiac conditions. This review looks at the current state of cardiac MRI, indicates those areas where MRI has become established as a reliable diagnostic technique and discusses future developments.

Complete MR angiography and Doppler ultrasound as the sole imaging modalities prior to carotid endarterectomy.

OBJECTIVE: To assess the combination of duplex Doppler ultrasound (DUS) and complete carotid magnetic resonance angiography (MRA) for the non-invasive imaging of carotid disease and their effect on outcomes. Determine inter-reader agreement of carotid MRA. MATERIALS AND METHODS: One-hundred and ten carotid bifurcations were evaluated using DUS, 2D and 3D time-of-flight MRA from the aortic arch to the Circle of Willis in 55 patients. Percentage stenoses were determined by two blinded readers using standardized criteria. Clinical follow-up was by chart review. RESULTS: Correlation of Doppler and MRA was excellent (r=0.903, P<0.001). Inter-reader agreement (K) for MRA was good: internal carotid artery (ICA) (0.750), external carotid artery (ECA) (0.674) and common carotid artery (CCA) (0.410). Differences in CCA readings were due to minor differences in categorizing lesions as CCA versus ICA or ECA. MRA and Doppler detected nine occluded ICAs. Two DUS occlusions had ICA flow by MRA; one due to a reconstituted precavernous ICA, one a near occluded vessel. Five patients (9%) had surgical management modified by MRA with four not having surgery: three distal ICA/Siphon occlusions and one less severe stenosis by MRA. One tandem lesion not visualized by DUS was surgically significant. Nine aortic arch abnormalities had no surgical impact, possibly due to small sample size. Of 41 endarterectomies, there were no complications from errors of diagnosis. CONCLUSION: Carotid MRA correlates well with DUS with good inter-reader agreement. MRA confirms Doppler findings, expands anatomical information and identifies tandem lesions from the aortic arch to the Circle of Willis which can affect surgical management. This approach to carotid artery imaging appears to have no negative effect on surgical outcome.

MRI and echocardiography: how do they compare in adults?

TTE with color flow imaging remains the most appropriate initial method for imaging CHD in adults. In many patients with minor abnormalities, this will be the only imaging required. For complicated intracardiac anomalies not well shown by TTE, TEE or MRI are usually adequate with the choice of technique being dependent on the availability of appropriate equipment and expertise. For great vessel abnormalities, further evaluation with MRI and MRA is most appropriate. In patients suspected of having significant systemic or pulmonary venous abnormalities or abnormalities of the aortic arch, MRI and MRA should be regarded as the definitive imaging technique. MRI and MRA are robust methods for evaluating intracardiac disease and can provide accurate information on cardiac chamber anatomy relationships, valvar lesions, and shunts. However, in most patients, this information is provided more rapidly and cost effectively by color Doppler echocardiography.