Use of MRI as an Alternative to Fluoroscopy

Of the primary imaging modalities (radiography, ultrasound, computed tomography, nuclear medicine, magnetic resonance), magnetic resonance imaging (MRI) is the most novel of the five used today. Despite the longer time and higher costs, which limit its use, the lack of ionizing radiation makes MRI attractive. For this reason, many research initiatives are aimed at expanding the role MRI has in modern medicine.

MRI has found success in replacing at least some fluoroscopic diagnostic studies. Although it is unlikely that MRI will soon replace fluoroscopic guidance for most invasive procedures, recent work is highlighted below.

MRI Alternatives for Diagnostic Fluoroscopy

Most diagnostic procedures performed using fluoroscopic imaging are unlikely to be replaced by MRI, but MRI is beginning to replace certain procedures (e.g., conventional angiograms, defocography). Other procedures are primarily in the research phase (e.g., swallowing studies, cystourethrogram), although human studies offer promise for their utilization in the not-too-distant future.

References

Neurovascular

1. Delgado Almandoz JE, Jagadeesan BD, Refai D, et al. Diagnostic yield of computed tomography angiography and magnetic resonance angiography in patients with catheter angiography-negative subarachnoid hemorrhage. J Neurosurg. 2012. 117(2):309–15. Available at: http://www.ncbi.nlm.nih.gov/pubmed/22680242. Accessed October 14, 2014.

Cardiac

1. Bluemke DA, Achenbach S, Budoff M, et al. Noninvasive coronary artery imaging: magnetic resonance angiography and multidetector computed tomography angiography: a scientific statement from the American Heart Association Committee on Cardiovascular Imaging and Intervention of the Council on Cardiovascular Radiology and Intervention, and the Councils on Clinical Cardiology and Cardiovascular Disease in the Young. Circulation. 2008. 118(5):586–606. Available at: http://circ.ahajournals.org/content/118/5/586.full. Accessed October 13, 2014.
2. Schuetz GM, Zacharopoulou NM, Schlattmann P, Dewey M. Meta-analysis: noninvasive coronary angiography using computed tomography versus magnetic resonance imaging. Annals of Internal Medicine Review, 2010. 152(3):176-177. Available at: http://annals.org/article.aspx?articleid=745561. Accessed October 13, 2014.

Thoracoabdominal/Body

1. Yucel EK, Anderson CM, Edelman RR, et al. Magnetic resonance angiography: update on applications for extracranial arteries. Circulation. 1999. 100(22):2284–2301. Available at: http://circ.ahajournals.org/content/100/22/2284.full. Accessed October 13, 2014.

Musculoskeletal

1. Stepansky F, Hecht EM, Rivera R, Hirsh LE, Taouli B, Kaur M, and Lee VS. Dynamic MR angiography of upper extremity vascular disease: pictorial review. RadioGraphics, 2008. 28(1) Online Only. Available at: http://pubs.rsna.org/doi/full/10.1148/radiol.e28. Accessed October 13, 2014.
2. Bode AS, Planken RN, Merkx MAG, et al. Feasibility of non-contrast-enhanced magnetic resonance angiography for imaging upper extremity vasculature prior to vascular access creation. Eur J Vasc Endovasc Surg, 2012. 43(1):88–94. Available at: http://www.sciencedirect.com/science/article/pii/S1078588411005818. Accessed October 13, 2014.
3. Koelemay MW, Lijmer JG, Stoker J, Legemate DA, Bossuyt PM. Magnetic resonance angiography for the evaluation of lower extremity arterial disease: a meta-analysis. JAMA, 2001. 285(10):1338-1345. Available at: http://jama.jamanetwork.com/article.aspx?articleid=193637. Accessed October 13, 2014.
4. Menke J, Larsen J. Meta-analysis: accuracy of contrast-enhanced magnetic resonance angiography for assessing steno-occlusions in peripheral arterial disease. Annals of Internal Medicine Review, 2010. 153:325-334. Available at: http://annals.org/article.aspx?articleid=746020. Accessed October 13, 2014.

Other

1. Frydrychowicz A, François CJ, Turski PA. Four-dimensional phase contrast magnetic resonance angiography: potential clinical applications. Eur J Radiol. 2011. 80(1):24–35. Available at: http://www.ejradiology.com/article/S0720-048X(11)00138-0/fulltext. Accessed October 13, 2014.
2. Hartung MP, Grist TM, François CJ. Magnetic resonance angiography: current status and future directions. J Cardiovasc Magn Reson, 2011. 13(1):19. Available at: http://www.jcmr-online.com/content/13/1/19. Accessed October 13, 2014.

Defocography

Primarily used to evaluate for prolapse and pelvic musculature, defocography has historically been a primarily fluoroscopic study. Today, in centers with equipment capable of conducting the study, MR defocography can be substituted, providing much more information that fluoroscopic evaluation cannot provide.

References

1. Brennan D, Williams G, Kruskal J. Practical performance of defecography for the evaluation of constipation and incontinence. Semin Ultrasound CT MR. 2008. 29(6):420–6. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19166039. Accessed July 28, 2014.
2. Hetzer FH, Andreisek G, Tsagari C, Sahrbacher U, Weishaupt D. MR defecography in patients with fecal incontinence: imaging findings and their effect on surgical management. Radiology, 2006. 240(2):449–57. Available at: http://pubs.rsna.org/doi/pdf/10.1148/radiol.2401050648. Accessed October 13, 2014.

Swallow Evaluation

With the expansion of speech-language pathology as a field, the video-fluoroscopic swallowing study (VFSS) is a relatively common procedure. Although in its infancy, real-time MR swallow evaluation is a promising field, improving VFSS by removing ionizing radiation and providing axial plane evaluation. The latter may obviate the need for flexible endoscopic evaluation. Interestingly, pineapple juice, with its inherently high manganese content, provides an optimal (and more palatable) oral contrast agent.

References

1. Zu Y, Narayanan SS, Kim Y, et al. Evaluation of swallow function after tongue cancer treatment using real-time magnetic resonance imaging: a pilot study. JAMA Otolaryngol Head Neck Surg, 2013;139(12):1312-1319. Available at: http://archotol.jamanetwork.com/article.aspx?articleid=1762476. Accessed October 13, 2014.
2. Zhang S, Olthoff A, Frahm J. Real-time magnetic resonance imaging of normal swallowing. J Magn Reson Imaging, 2012. 35(6):1372–9. Available at: http://onlinelibrary.wiley.com/doi/10.1002/jmri.23591/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false. Accessed October 13, 2014.

Voiding Cystourethrogram

Between nuclear radionuclide cystography and fluoroscopic voiding cystourethrogram, evaluation of the genitourinary system for reflux involves some form of radiation. As most of these studies are conducted in children, MR cystourethrograms are a novel technique, primarily in the research stages, that may help reduced fluoroscopic studies.

References

1. Johnin K, Takazakura R, Furukawa A, et al. Magnetic resonance voiding cystourethrography (MRVCUG): a potential alternative to standard VCUG. J Magn Reson Imaging, 2013. 38(4):897–904. Available at: http://www.ncbi.nlm.nih.gov/pubmed/23417820. Accessed October 13, 2014.

MRI Alternatives for Interventional Procedures

Primarily in the research stages, both non-vascular and vascular interventions using MRI exist.

Body/Non-catheter-directed Procedures

With the possible exception of breast mass biopsy/localization in a handful of centers, routine use of MR-guidance for non-catheter interventions is not routine. Exciting human studies, primarily in biopsy localization, offer future promise.

References

1. Moche M, Zajonz D, Kahn T, Busse H. MRI-guided procedures in various regions of the body using a robotic assistance system in a closed-bore scanner: preliminary clinical experience and limitations. J Magn Reson Imaging, 2010. 31(4):964-974. Available at: http://onlinelibrary.wiley.com/doi/10.1002/jmri.21990/abstract. Accessed October 13, 2014.

Catheter-directed Procedures

Catheter-based cardiac interventions (e.g., congenital abnormalities, ablative procedures) are the most well-documented examples of an MR-based, catheter-directed procedure. Human studies primarily exist in cardiac applications.

References

1. Geva T, Marshall AC. Magnetic resonance imaging-guided catheter interventions in congenital heart disease. Circulation, 2006. 113(8):1051–2. Available at: http://circ.ahajournals.org/content/113/8/1051.full. Accessed October 13, 2014.