Use Of Gadolinium-enhanced Magnetic Resonance Imaging Research Articles

Quantitative Assessment of the Vascularity of the Talus with Gadolinium-Enhanced Magnetic Resonance Imaging

The purpose of this study was to quantify the various arterial contributions to the talus with use of magnetic resonance imaging (MRI). The arterial anatomy of the talus was studied in ten pairs of fresh-frozen cadaver limbs with use of gadolinium-enhanced MRI in addition to gross dissection following latex injection. MRI proved useful to confirm the presence of specific arterial branches in situ as well as to demonstrate the rich anastomosis network in and around the talus. We further examined the MRI studies to delineate the quantitative contribution of each of the three main arteries to the talus and to each quadrant of the talus (anteromedial [0], anterolateral [1], posterolateral [2], and posteromedial [3]). The peroneal artery contributed 16.9% of the blood supply to the talus; the anterior tibial artery, 36.2%; and the posterior tibial artery, 47.0%. The contribution of the anterior tibial artery was greatest in quadrant 0, whereas the contribution of the posterior tibial artery was greatest in quadrants 1, 2, and 3. The peroneal artery did not make the greatest contribution in any quadrant. In contrast to the findings in previous studies, we found that a substantial portion of the talar blood supply can enter posteriorly, which helps to explain why all talar neck fractures do not result in osteonecrosis. This finding, along with a very rich and redundant intraosseous pattern of anastomosis with contributions from all three vessels in each quadrant of the talus, may explain the low occurrence of osteonecrosis in association with talar neck fractures.

Arterial Anatomy of the Talus: A Cadaver and Gadolinium-Enhanced MRI Study

Avascular necrosis following a fracture of the talar neck may be secondary to the injury itself, or may result from the surgical approach and exposure during treatment. We sought to define the arterial anatomy of the talus using gadolinium-enhanced magnetic resonance imaging (MRI) and through gross dissection following latex injection of cadaver limbs. The use of gadolinium-enhanced MRI for the evaluation of the arterial supply of the talus has not been previously reported. We utilized 12 fresh frozen cadaver limbs to study the arterial anatomy of the talus. The anterior tibial, posterior tibial, and peroneal arteries were isolated and cannulated with polyethylene catheters. Gadolinium was injected into the cannulas, and conventional MRI sequences including suppressed and unsuppressed 3D gradient echo sequences obtained. Following MRI, latex was injected into the cannulas and gross dissection performed. In addition, the vascular constraints to anteromedial and anterolateral approaches to the talus were defined. MRI proved useful in the present study to confirm the presence of specific arterial branches in situ, as well as to demonstrate the rich anastomotic network in and around the talus. A branch to the medial talar neck that has not been previously identified is described which was found in nine of the specimens. This newly described branch to the medial talar neck was consistently noted to be lacerated following a standard anteromedial approach to the talus. The use of gadolinium-enhanced MRI provided very detailed images demonstrating a rich and complex anastomotic arterial network that surrounds and perforates the talus. A thorough understanding of the anatomy and meticulous dissection are essential to prevent unnecessary further injury to the vasculature when treating fractures of the talus.

Controversies in Magnetic Resonance Imaging of the Hip

One of the first musculoskeletal areas to be imaged by magnetic resonance (MR) was the hip. Early on, and even today, the most frequent indication for imaging of the hip has been for the evaluation of osteonecrosis and related diseases. Despite the long history of MR imaging of osteonecrosis, there still exist many controversies. This article will look at three of these: (a) What is the best way of imaging early osteonecrosis? This question has proven to be particularly important in the evaluation of the posttraumatic patient. We provide some preliminary evidence that the use of gadolinium-enhanced MR imaging may be helpful. Specifically, gadolinium fails to enhance areas of early osteonecrosis while surrounding uninvolved areas do enhance. (b) How should the patient with "MR bone marrow edema of the hip" be evaluated and treated? If there is radiographic osteopenia, the assumption is that this represents transient osteoporosis (a self-limited disease) and no treatment is necessary. However, if no osteopenia is present, the diagnosis and treatment become more problematic. A decision-making algorithm is presented to help overcome this dilemma. (c) Is documented osteonecrosis of the hip ever reversible without surgical intervention? Work done with renal transplant patients suggests that the answer to this question is yes, but work reported from Europe casts some doubt on this conclusion.

Use of gadolinium-enhanced MR imaging for differentiating mucoceles from neoplasms in the paranasal sinuses.

The purpose of this study was to determine whether additional clinically useful information could be obtained from gadolinium-enhanced magnetic resonance (MR) imaging compared with the information obtained from nonenhanced MR imaging and computed tomography (CT). Therefore, the authors selected 41 patients, whose results at CT examinations demonstrated a variety of pathologic conditions of the paranasal sinuses, to undergo MR imaging both with and without the use of gadopentetate dimeglumine for contrast enhancement. In 22 of 35 cases of neoplasms and mucoceles occurring separately, the lesions were correctly differentiated by established MR signal criteria alone. However, 32 of these 35 cases were accurately differentiated when gadolinium-enhanced MR images were obtained. Six cases demonstrated co-existing neoplasm and mucocele: Gadolinium-enhanced MR enabled correct differentiation of five of these lesions, while unenhanced MR enabled correct differentiation of three. On the basis of these results, the authors conclude that the use of gadopentetate dimeglumine for contrast enhancement at MR imaging is useful for differentiating mucoceles from neoplasms in the sinonasal tract.