Publication for the Philips MRI Community Issue 40 May 2010

Transcription

1 FieldStrength Publication for the Philips MRI Community Issue 40 May 2010 Achieva 1.5T XR enables excellent cardiac imaging at Cleveland Clinic Rampable system provides 3.0T gradients for improved spatial resolution, overall image quality This article is part of Field Strength issue 40, May 2010

2 Achieva 1.5T XR enables excellent cardiac imaging at Cleveland Clinic Rampable system provides 3.0T gradients for improved spatial resolution, overall image quality The Cardiovascular Imaging section of the world-renowned Cleveland Clinic performs about 2,500 cardiovascular MRI exams every month, mainly related to aortic vascular disease, ischemic heart disease and infiltrative cardiomyopathies. The Cleveland Clinic chose Achieva 1.5T XR for its cardiac work because of its excellent image quality and rampability; it s the only 1.5T scanner upgradeable to 3.0T without a magnet swap. Scott D. Flamm, MD is Head of Cardiovascular Imaging at Cleveland Clinic. He is a staff physician with joint appointments to the Robert and Suzanne Tomsich Department of Cardiovascular Medicine and the Division of Pediatrics. Before, Dr. Flamm was Director of MRI and Cardiovascular MRI Research at the Texas Heart Institute at St. Luke s Episcopal Hospital in Houston, Texas. Scott D. Flamm, MD, Head, Section of Cardiovascular Imaging, Imaging Institute, Cleveland Clinic, says, We were intrigued and impressed that the Achieva XR is a 3.0T scanner that can begin its life at 1.5T and then be ramped up to 3.0T with a very simple conversion and no forklift. Even when it s running at 1.5T, we have the gradient capabilities of a 3.0T scanner. The Clinic will likely ramp up to 3.0T within the year. Achieva XR offers multiple advantages for cardiac work There are a number of things that I really like about the Achieva XR, says Dr. Flamm. In particular, the integration of ExamCards. We are able to set up excellent discrete and focused protocols for cardiac examinations. It s a terrific tool that allows us to get systematically consistent examinations. Shorter scan times are another advantage of using Achieva XR. I monitor our scan times each quarter, and they have decreased consistently after Achieva XR was installed, says Dr. Flamm. Even when it s running at 1.5T, we have the gradient capabilities of a 3.0T scanner. Achieva 1.5T XR at Cleveland Clinic 14 FieldStrength Issue 40 May 2010

3 Coronal oblique view Phase contrast study Magnitude image Phase image Aortic regurgitation A 62-year-old male presented with history of shortness of breath for two years. The coronal oblique view shows a moderate jet of aortic regurgitation (arrow) into the left ventricle. In addition, there is mild dilation of the ascending aorta. A phase contrast study (PCA) is performed at the mid ascending aorta (circular region of interest) to determine the severity of the aortic regurgitation. The regurgitation fraction, identified as flow below the baseline (blue line) during diastole was 27%. Final diagnosis is moderate aortic regurgitation. On Achieva 1.5T XR, use of SENSE parallel acquisition allows for retrospectively gated velocity-encoded phase-contrast techniques to be performed in a breath hold. Dr. Flamm says he doesn t aim for shorter breath holds with Achieva XR 3.0T gradients, but better images. We are able to have shorter TRs and TEs and, as a result, in the same breath hold, we are able to accomplish imaging that has higher spatial resolution, higher temporal resolution, or both. Even if we could reduce the breath hold length to 8 seconds or even 6 seconds, we d rather maximize our imaging for each patient s breath hold. I monitor our scan times each quarter, and they have decreased consistently with Achieva XR. The Clinic uses the SENSE XL Torso coil, which has a very large coverage area. Many of Dr. Flamm s scans extend from the arch of the aorta to the bifurcation of the aorta. He can often acquire this in one scan with the SENSE XL Torso coil. Multiple sequences help provide a more complete diagnosis For each cardiac exam, Dr. Flamm includes additional scans that enable a thorough diagnosis, such as a series of axial images through the chest, with both bright blood and dark blood sequences instead of only focused, small field of view images of the heart. We do a flow quantification sequence, which is performed in an axial orientation at the level of the right pulmonary artery that allows us to calculate blood flow through the ascending aorta and ensure the valve is working properly. On the same imaging plane we have the superior vena cava and the right upper lobe pulmonary vein and evaluate the flow curves of both of those vessels, to categorize right and left atrial pressure, respectively, explains Dr. Flamm. Dr. Flamm acquires these additional flow quantification images with good reproducibility, within a single breath hold, and with retrospective gating to cover the entire cardiac cycle. These flow quantification sequences really have continued to get better and better, he says. This Achieva XR system seems to produce the most reliable that I have seen. FieldStrength 15

4 SSFP STIR Left atrial myxoma 51-year-old female with history of shortness of breath and transient ischemic attacks. The SSFP image shows a well-defined mass (arrows) with intermediate signal in the left atrium that is attached to the interatrial septum. There is no obstruction of the mitral valve. The STIR image shows heterogeneous, high signal in the left atrial mass (arrows) that is attached to the interatrial septum. The large left atrial tumor is most likely a myxoma. Cardiac MRI using Achieva 1.5T XR with 16-channel SENSE XL Torso coil. We are able to accomplish imaging that has higher spatial resolution, higher temporal resolution, or both. NetForum Visit the NetForum User Community for downloading Cardiac ExamCards. Dr. Flamm s Achieva 1.5T XR ExamCards will soon be available. 16 FieldStrength Issue 40 May 2010

5 3 chamber (LVOT) views SSFP Phase contrast EPI Phase contrast The EWS is a sophisticated cardiac MR workstation and analysis tool. Short axis views Hypertrophic cardiomyopathy A 37-year-old male presented with syncope and shortness of breath. There was no family history of sudden cardiac death. The short axis views show moderate to severe asymmetrical hypertrophy of the interventricular septum (arrows). The three-chamber (LVOT) views show a high velocity jet in the left ventricular outflow tract (arrowheads). Using the phase contrast sequence a velocity of 3.4 m/sec. is determined for this jet. Dr. Flamm also regularly performs functional non-cine imaging using a balanced FFE sequence. To detect infiltration within or permanent damage to the myocardium, we can use the balanced FFE sequence with an inversion recovery pulse. A variation on this technique is a Phase Sensitive Inversion Recovery (PSIR) acquisition. A PSIR approach is less sensitive to variations in choice of the inversion time TI, so it allows us to go through an examination with fewer adjustments to TI, which speeds our exam workflow. Normal myocardium shows up on this scan as black, while damaged myocardium shows up as white. For ischemic disease the pulse sequence is particularly helpful as we have nearly a binary evaluation process black or white. Workflow improves with EWS workstation The integration of the ExamCards with the Extended Workspace (EWS) is particularly advantageous, says Dr. Flamm. With the customizable display protocols and the tight integration with the EWS display protocols we can bring up a series of long and short axis images on a single display screen and have them all synchronized. It s very logical and efficient and clinically useful to be able to put images that are acquired in the same orientations together, as it enables you to directly match function with tissue characterization. The EWS is a sophisticated cardiac MR workstation and analysis tool. FieldStrength 17