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5. Unsupervised feature selection applied to content-based retrieval of lung images

Author

Dy, Jennifer G., Brodley, Carla E., Kak, Avi, Broderick, Lynn S., and Aisen, Alex M.

Subjects
Technology application, Diagnostic imaging -- Technology application, Image processing -- Technology application
Abstract

This paper describes a new hierarchical approach to content-based image retrieval called the "customized-queries" approach (CQA). Contrary to the single feature vector approach which tries to classify the query and retrieve similar images in one step, CQA uses multiple feature sets and a two-step approach to retrieval. The first step classifies the query according to the class labels of the images using the features that best discriminate the classes. The second step then retrieves the most similar images within the predicted class using the features customized to distinguish "subclasses" within that class. Needing to find the customized feature subset for each class led us to investigate feature selection for unsupervised learning. As a result, we developed a new algorithm called FSSEM (feature subset selection using expectation-maximization clustering). We applied our approach to a database of high resolution computed tomography lung images and show that CQA radically improves the retrieval precision over the single feature vector approach. To determine whether our CBIR system is helpful to physicians, we conducted an evaluation trial with eight radiologists. The results show that our system using CQA retrieval doubled the doctors' diagnostic accuracy. Index Terms--Image retrieval, feature selection, clustering, expectation-maximization, unsupervised learning.

Published
2003

6. Multicenter study of gadodiamide injection as a contrast agent in MR imaging of the brain and spine

Author

Sze, Gordon, Brant-Zawadzki, Michael, Haughton, Victor M., Maravilla, Kenneth R., McNamara, Michael T., Kumar, Ashok J., Aisen, Alex M., Dreisbach, James N., Bradley, William G., Jr., Weinreb, Jeffrey C., Drayer, Burton P., Tsuruda, Jay S., Hesselink, John R., Johnson, Carl E., Zimmerman, Robert D., and Weingast, Gail R.

Subjects
Central nervous system diseases, Central nervous system, Magnetic resonance imaging, Nonionic contrast media -- Evaluation, Health
Abstract

Magnetic resonance (MR) imaging is a diagnostic imaging technique that uses the magnetic properties of elements to produce clearly differentiated images of tissues and organs. One of its uses is imaging the head and spine for detecting abnormalities of the central nervous system (CNS). As with other imaging techniques, contrast agents often help enhance MR images and allow for more accurate detection of abnormalities. This study examined the effectiveness and safety of the nonionic compound gadodiamide in MR imaging. MR imaging of the brain and spine along with injection of gadodiamide was performed on 439 patients who had either suspected or known CNS abnormalities. Adverse side effects from the agent were reported by 46 (10.5 percent) of the patients. Headaches, nausea, and dizziness were the most commonly reported side effects; no serious side effects were reported. CNS abnormalities were detected by MR imaging, with or without the contrast agent, in 353 (80.4 percent) of the patients. The gadodiamide enhanced imaging of these abnormalities in 266 of the 353 patients. In 28 patients, no abnormality was seen when MR imaging without gadodiamide was performed. Gadodiamide enhancement changed the diagnosis for 70 patients and facilitated diagnosis for 190 patients. These results indicate that gadodiamide is both safe and effective for use as a MR imaging contrast agent when evaluating possible CNS abnormalities. (Consumer Summary produced by Reliance Medical Information, Inc.)

Published
1991

9. Body MR imaging and the local staging of neoplasms

Author

Aisen, Alex M.

Subjects
Magnetic resonance imaging, Pelvis -- Medical examination, Tumors -- Diagnosis, Health
Abstract

The diagnostic use of magnetic resonance (MR) imaging has increased beyond original expectations. It is used to characterize abnormalities in many areas of the body. Until recently, its use in abnormalities in the pelvic region has been more limited. Studies have shown MR to be useful in diagnosing tumors in the liver as well as in other organs of the pelvis, but for a number of reasons it is still not widely used. The lack of an effective and safe contrasting agent for imaging the bowels prevents MR from becoming the major diagnostic tool for most pelvic organs besides the liver. Motion caused by the heart and lungs interferes with MR imaging in this area. Recent research shows that MR imaging is useful in finding and characterizing localized tumors in pelvic organs, as motion is less of a problem with this use. Other research has shown the superiority of using MR over computed tomography (CT) in imaging localized tumors in other areas of the body. MR works especially well on organs surrounded by fat such as the uterus. The use of MR for finding rectal tumors has yielded mixed results, although new research has indicated that good results may be obtained if the techniques are used very carefully. MR does have its limitations. It is not highly successful in differentiating between normal and enlarged lymph nodes. It is also less effective in previously treated patients, where treatment has affected tissue. The future of MR is bright, nevertheless. Proper technique is vital to its use. Improved technology and development of new contrast agents will expand its scope and power as a diagnostic tool. (Consumer Summary produced by Reliance Medical Information, Inc.)

Published
1990

17. Reply

Author

Divisions of Neuroradiology and Magnetic Resonance Imaging, Department of Radiology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109, Gebarski, Stephen S., Gabrielsen, Trygve O., Gilman, Sid, Knake, James E., Latack, Joseph T., Aisen, Alex M., Divisions of Neuroradiology and Magnetic Resonance Imaging, Department of Radiology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109, Gebarski, Stephen S., Gabrielsen, Trygve O., Gilman, Sid, Knake, James E., Latack, Joseph T., and Aisen, Alex M.

Abstract

No Abstract.

Published
2007

18. Magnetic resonance imaging of femoral head development in roentgenographically normal patients

Author

University of Michigan Medical School, Ann Arbor, Michigan, USA, Department of Radiology, University Hospital, 48109, Ann Arbor, MI, USA, Ann Arbor, Aisen, Alex M., Braunstein, Ethan M., Martel, William, Littrup, Peter J., University of Michigan Medical School, Ann Arbor, Michigan, USA, Department of Radiology, University Hospital, 48109, Ann Arbor, MI, USA, Ann Arbor, Aisen, Alex M., Braunstein, Ethan M., Martel, William, and Littrup, Peter J.

Abstract

Magnetic resonance images (MRI) of 22 patients with roentgenographically normal hips were reviewed retrospectively and the findings categorized according to age. With increasing maturity, the MR intensity of the femoral heads on spin echo images increased, as marrow fat became a dominant tissue in the head. The femoral head pattern was relatively inhomogeneous, with a broad band of diminished intensity extending in a posteromedial to anterolateral direction, corresponding to the pattern of trabecular bone. The femoral capital epiphyses were visible in younger patients as structures of bright intensity which remained evident through early adulthood. The articular cartilage of the hip joint was noted as a distinctive “halo” around the femoral head. An understanding of the MR pattern of the normal hip will aid in the early recognition of pathologic conditions, such as osteonecrosis.

Published
2006

19. Abstracts of scientific presentations

Author

University of Michigan, Ann Arbor, MI, University of Michigan Medical Center, Ann Arbor, MI, Georgetown University Hospital, Washington DC, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, Uniformed Services University of the Health Sciences, Bethesda, MD, Mayo Clinic, Rochester, MN, Henry Ford Hospital, Detroit, MI, Hospital of the University of Pennsylvania, Philadelphia, PA, New England Deaconess Hospital, Boston, MA, University of California, San Francisco, CA, Mallinckrodt Institute of Radiology, St. Louis, MO, Bowman Gray School of Medicine, Winston-Salem, NC, Medical College of Wisconsin, Milwaukee, WI, Massachusetts General Hospital, Boston, MA; Massachusetts General Hospital, Boston, MA, William Beaumont Hospital, Royal Oak, MI, McMaster University, Canada, Freie Universit??t Berlin and Research Laboratories of Schering, Berlin, Federal Republic of Germany, The Mason Clinic, Seattle, WA, The Johns Hopkins Medical Institutions, Baltimore, MD, University of North Carolina, Chapel Hill, NC, Duke University Medical Center, Durham, NC, Massachusetts General Hospital, Boston, MA, Hahnemann University, Philadelphia, PA, University of Rochester Medical Center, Rochester, NY, Medical College of Virginia, Richmond, VA, Downstate Medical Center, New York University Medical Center, North Shore University Hospital, St. Luke's-Roosevelt Medical Center, Cornell University Medical College, Columbia University College of Physicians and Surgeons, New York, NY, Department of Radiology, Mayo Clinic, Rochester, MN, University of Iowa Hospitals and Clinics, Iowa City, IA, St. Vincent Hospital, Worcester, MA, New York University Medical Center, New York, NY, First Department of Medicine, School of Medicine, Chiba University, Japan, Mallinckrodt Institute of Radiology, St. Louis, MO; Mallinckrodt Institute of Radiology, St. Louis, MO, Ann Arbor, Clark, J., Munitz, H. A., Benjamin, S. B., Frager, J., Janower, M. L., Wolf, E. L., Frager, D., Kligerman, M., Brandt, L. J., Utz, J., Rubinsky, B., Baker, M. E., Kelvin, F. M., Thompson, W. M., Williams, D. M., Aisen, Alex M., Johnson, C. D., Herfkens, R., Kimura, K., Wolf, K. J., Ohto, M., Javors, B. R., Ebara, M., Weyman, P. J., Swantkowski, T. M., Sammon, J., Cho, S. R., Mauro, Matthew A., Shea, W., Bozymski, E. M., Demas, B., Charboneau, J. W., Hanelin, L. G., James, E., Haskin, P. H., Sheedy, P., Kastan, D., Stewart, E., Sugiura, N., Bernstein, L. H., Dachman, A. H., Stephens, D. H., Agha, Farooq P., Ell, S. R., Rubesin, S. E., Patrick, D. H., Jenkins, R., Cady, B., Ferrucci, J. T., Onik, G., Felix, R., Frost, R. A., Langer, J., Lawson, T., Halpert, R. D., Feczko, P. J., Lee, Marie E., Stark, D. D., Chen, Y. M., Skucas, J., Steele, G., Schwab, F. J., Martel, William, Jaffe, Mark H., Cho, Kyung J., Murakami, J., Listinsky, C., Jones, B., Laufer, I., Halpert, R., Kerlan, R., Wu, W. C., Gelfand, D. W., Miller, T., Teefey, S., Goldberg, H. I., Ormson, M. J., Grant, E. G., Ziessman, H., Silverman, P. M., Hohn, D., Zeman, R. K., Lichtenstein, J. E., Khettry, U., Kane, R., Ott, D. J., Somers, S., Lamping, D., Schroeder, K. W., Saini, S., Dodds, W., Stevenson, G., Turner, M. A., Charboneau, W., Choyke, P. L., Weinmann, H. -J., Darweesh, R., MacCarty, R. L., Clark, L. R., Hulnick, D. H., Reiman, T. H., Balfe, D. M., Schwab, R. E., Roemer, T., Bree, Robert L., McDermott, W., Ackerman, L., Nichols, J. B., Bradley, J. J., Wittenberg, J., Clouse, M., Messmer, J. M., Gilbert, J., Gudex, D., Hooyman, J. R., Glick, S. N., Carpenter, H. A., Carlson, H. C., Ni, X. Y., Teplick, S. K., Farman, J., Katz, J., Lu, C. C., Barloon, T., Franken, E. A., Balthazar, Emil J., Beneventano, T. C., Levine, M. S., Hamm, B., Bashist, B., Staab, E. V., Cooper, C., Megibow, A. J., University of Michigan, Ann Arbor, MI, University of Michigan Medical Center, Ann Arbor, MI, Georgetown University Hospital, Washington DC, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, Uniformed Services University of the Health Sciences, Bethesda, MD, Mayo Clinic, Rochester, MN, Henry Ford Hospital, Detroit, MI, Hospital of the University of Pennsylvania, Philadelphia, PA, New England Deaconess Hospital, Boston, MA, University of California, San Francisco, CA, Mallinckrodt Institute of Radiology, St. Louis, MO, Bowman Gray School of Medicine, Winston-Salem, NC, Medical College of Wisconsin, Milwaukee, WI, Massachusetts General Hospital, Boston, MA; Massachusetts General Hospital, Boston, MA, William Beaumont Hospital, Royal Oak, MI, McMaster University, Canada, Freie Universit??t Berlin and Research Laboratories of Schering, Berlin, Federal Republic of Germany, The Mason Clinic, Seattle, WA, The Johns Hopkins Medical Institutions, Baltimore, MD, University of North Carolina, Chapel Hill, NC, Duke University Medical Center, Durham, NC, Massachusetts General Hospital, Boston, MA, Hahnemann University, Philadelphia, PA, University of Rochester Medical Center, Rochester, NY, Medical College of Virginia, Richmond, VA, Downstate Medical Center, New York University Medical Center, North Shore University Hospital, St. Luke's-Roosevelt Medical Center, Cornell University Medical College, Columbia University College of Physicians and Surgeons, New York, NY, Department of Radiology, Mayo Clinic, Rochester, MN, University of Iowa Hospitals and Clinics, Iowa City, IA, St. Vincent Hospital, Worcester, MA, New York University Medical Center, New York, NY, First Department of Medicine, School of Medicine, Chiba University, Japan, Mallinckrodt Institute of Radiology, St. Louis, MO; Mallinckrodt Institute of Radiology, St. Louis, MO, Ann Arbor, Clark, J., Munitz, H. A., Benjamin, S. B., Frager, J., Janower, M. L., Wolf, E. L., Frager, D., Kligerman, M., Brandt, L. J., Utz, J., Rubinsky, B., Baker, M. E., Kelvin, F. M., Thompson, W. M., Williams, D. M., Aisen, Alex M., Johnson, C. D., Herfkens, R., Kimura, K., Wolf, K. J., Ohto, M., Javors, B. R., Ebara, M., Weyman, P. J., Swantkowski, T. M., Sammon, J., Cho, S. R., Mauro, Matthew A., Shea, W., Bozymski, E. M., Demas, B., Charboneau, J. W., Hanelin, L. G., James, E., Haskin, P. H., Sheedy, P., Kastan, D., Stewart, E., Sugiura, N., Bernstein, L. H., Dachman, A. H., Stephens, D. H., Agha, Farooq P., Ell, S. R., Rubesin, S. E., Patrick, D. H., Jenkins, R., Cady, B., Ferrucci, J. T., Onik, G., Felix, R., Frost, R. A., Langer, J., Lawson, T., Halpert, R. D., Feczko, P. J., Lee, Marie E., Stark, D. D., Chen, Y. M., Skucas, J., Steele, G., Schwab, F. J., Martel, William, Jaffe, Mark H., Cho, Kyung J., Murakami, J., Listinsky, C., Jones, B., Laufer, I., Halpert, R., Kerlan, R., Wu, W. C., Gelfand, D. W., Miller, T., Teefey, S., Goldberg, H. I., Ormson, M. J., Grant, E. G., Ziessman, H., Silverman, P. M., Hohn, D., Zeman, R. K., Lichtenstein, J. E., Khettry, U., Kane, R., Ott, D. J., Somers, S., Lamping, D., Schroeder, K. W., Saini, S., Dodds, W., Stevenson, G., Turner, M. A., Charboneau, W., Choyke, P. L., Weinmann, H. -J., Darweesh, R., MacCarty, R. L., Clark, L. R., Hulnick, D. H., Reiman, T. H., Balfe, D. M., Schwab, R. E., Roemer, T., Bree, Robert L., McDermott, W., Ackerman, L., Nichols, J. B., Bradley, J. J., Wittenberg, J., Clouse, M., Messmer, J. M., Gilbert, J., Gudex, D., Hooyman, J. R., Glick, S. N., Carpenter, H. A., Carlson, H. C., Ni, X. Y., Teplick, S. K., Farman, J., Katz, J., Lu, C. C., Barloon, T., Franken, E. A., Balthazar, Emil J., Beneventano, T. C., Levine, M. S., Hamm, B., Bashist, B., Staab, E. V., Cooper, C., and Megibow, A. J.

Published
2006

20. MR imaging in hydatid disease of the liver

Author

Department of Radiology, University of Michigan Hospitals, Box 0555, 48109, Ann Arbor, MI, USA, Ann Arbor, Hoff, Frederick L., Aisen, Alex M., Walden, Mark E., Glazer, Gary M., Department of Radiology, University of Michigan Hospitals, Box 0555, 48109, Ann Arbor, MI, USA, Ann Arbor, Hoff, Frederick L., Aisen, Alex M., Walden, Mark E., and Glazer, Gary M.

Abstract

We describe the appearance on MR of hydatid disease of the liver in 2 patients. The lesions were well demonstrated using spin-echo pulse sequences, and could be easily seen with either T 1 or T 2 weighting; however, maximum information was obtained using both. In these 2 cases, a thin, low signal boundary was noted around the cysts; this finding may prove useful in differential diagnosis.

Published
2006

21. Preliminary clinical trial of gadodiamide injection: A new nonionic gadolinium contrast agent for MR imaging

Author

Department of Radiology, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030, Department of Radiology, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030 ; Department of Radiology, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030, Kaplan, Gabriela D., Aisen, Alex M., Aravapalli, S. Rao, Department of Radiology, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030, Department of Radiology, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030 ; Department of Radiology, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030, Kaplan, Gabriela D., Aisen, Alex M., and Aravapalli, S. Rao

Abstract

The safety and efficacy of a newly developed intravenous formulation of the nonionic contrast agent gadolinium diethylenetriaminepentaacetic acid- bis (methylamide), formulated as gadodia-mide injection, was investigated. In 30 patients who underwent spin-echo magnetic resonance (MR) imaging before and after contrast agent enhancement, the enhanced images had characteristics judged similar to those of images enhanced by means of available gadolinium compounds. In 15 patients, contrast agent administration was of major diagnostic help, either revealing lesions not apparent without enhancement or providing important lesion characterization. In 12 patients, the lack of abnormal enhancement patterns was important in excluding the presence of disease. In three patients, the contrast agent did not provide information additional to that obtained with the unenhanced T1- and T2-weighted images. No clinically significant changes were observed in vital signs, neurologic status, or laboratory results. The authors conclude that, in this limited series, gadodiamide injection proved to be a safe and useful MR imaging contrast agent for evaluation of the central nervous system and surrounding structures.

Published
2006

22. Magnetization transfer contrast imaging of hepatic neoplasms

Author

Department of Radiology, University of Michigan Medical Center, Ann Arbor, MI 48109-0030, USA, Hollett, Michael D., Aisen, Alex M., Yeung, Hong N., Francis, Isaac R., Bree, Robert L., Department of Radiology, University of Michigan Medical Center, Ann Arbor, MI 48109-0030, USA, Hollett, Michael D., Aisen, Alex M., Yeung, Hong N., Francis, Isaac R., and Bree, Robert L.

Abstract

A method of performing magnetization transfer contrast (MTC) using a pulse sequence based on a series of onresonance binomial pulses preceding a conventional spin-echo sequence has been recently described. We investigated this technique in the evaluation of circumscribed hepatic neoplasms on a 0.5T imager. Conventional spin-echo imaging was performed in 18 patients with hepatic neoplasms, 15 with primary or metastatic hepatic neoplasms, and 3 with cavernous hemangiomas. The T1-weighted sequence was repeated following MTC saturation in 7 patients and the proton density sequence was repeated following MTC saturation in 13 patients (both were used in two patients). The mean lesion-to-liver contrast for neoplasms worsened with T1-MTC (0.87 vs. 1.04), but improved slightly with proton density-MTC (1.10 vs. 1.22) when compared to the corresponding non-MTC spinecho images. However, these differences were not statistically significant (p = .19 and p = .16, respectively). The limited data on cavernous hemangiomas does not suggest these have consistently different MTC imaging characteristics from other hepatic neoplasms. In conclusion, MTC imaging using a binomial saturation pulse did not offer significant improvement in contrast between hepatic neoplasms and normal liver. Refinements of the binomial pulse sequence will be necessary if a consistent improvement in lesion sensitivity is to be achieved. Evaluation of its role in increasing diagnostic specificity will require further investigation.

Published
2006

23. Transmural distribution of myocardial edema by NMR relaxometry following myocardial ischemia and reperfusion

Author

Department of Radiology, University of Michigan Medical Center, Ann Arbor, Mich., USA; Cardiology Division, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Mich., USA, Department of Radiology, University of Michigan Medical Center, Ann Arbor, Mich., USA, Cardiology Division, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Mich., USA; Department of Radiology, University of Michigan Medical Center, Ann Arbor, Mich., USA, Karolle, Beth L., Carlson, Robert E., Aisen, Alex M., Buda, Andrew J., Department of Radiology, University of Michigan Medical Center, Ann Arbor, Mich., USA; Cardiology Division, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Mich., USA, Department of Radiology, University of Michigan Medical Center, Ann Arbor, Mich., USA, Cardiology Division, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Mich., USA; Department of Radiology, University of Michigan Medical Center, Ann Arbor, Mich., USA, Karolle, Beth L., Carlson, Robert E., Aisen, Alex M., and Buda, Andrew J.

Abstract

To determine the distribution and extent of myocardial edema resulting from ischemia and reperfusion, seven open-chest dogs underwent occlusion of the left circumflex coronary artery for 2 hours (group I), and 10 underwent occlusion for 2 hours and reperfusion for 2 hours (group II). Proton nuclear magnetic resonance spectroscopy (T1 and T2 relaxation times) and percent water content were determined to quantitate the amount of edema. There was a transmural increase of the T1 relaxation time of the central ischemic zone in groups I and II, although this increase was significantly greater in group II in both the subendocardium (group I = 707.8 +/- 12.5 msec, group II = 813.2 +/- 36.2 msec; p p p p p <0.01) in the subendocardium in both groups. Similar increases were noted in the percent water content of the myocardium. Thus T1 and T2 relaxation times lengthened with an increase in myocardial water content following occulusion, and these relaxation times were augmented by reperfusion. We conclude that ischemia-induced edema occurs in a transmural distribution from subendocardium to subepicardium following occlusion, and this edema is further enhanced by reperfusion.

Published
2006

24. Effects of diltiazem on phosphate metabolism in ischemic and reperfused myocardium using phosphorus31 nuclear magnetic resonance spectroscopy in vivo

Author

Department of Radiology, University of Michigan Medical Center, the University of Michigan, Ann Arbor, Mich., USA; Cardiology Division, Department of Internal Medicine, Ann Arbor, Mich., USA., Cardiology Division, Department of Internal Medicine, Ann Arbor, Mich., USA; Department of Radiology, University of Michigan Medical Center, University of Michigan, Ann Arbor, Mich., USA., Kavanaugh, Kevin M., Aisen, Alex M., Fechner, Klaus P., Wroblewski, Lynette C., Chenevert, Thomas L., Buda, Andrew J., Department of Radiology, University of Michigan Medical Center, the University of Michigan, Ann Arbor, Mich., USA; Cardiology Division, Department of Internal Medicine, Ann Arbor, Mich., USA., Cardiology Division, Department of Internal Medicine, Ann Arbor, Mich., USA; Department of Radiology, University of Michigan Medical Center, University of Michigan, Ann Arbor, Mich., USA., Kavanaugh, Kevin M., Aisen, Alex M., Fechner, Klaus P., Wroblewski, Lynette C., Chenevert, Thomas L., and Buda, Andrew J.

Abstract

Diltiazem may provide a protective effect to ischemic and reperfused myocardium through preservation of high-energy phosphate metabolism. To test this hypothesis, rabbits had a 1.3 cm solenoidal coil placed over the myocardium to be rendered ischemic. Data were acquired with a 22 cm bore nuclear magnetic resonance spectrometer at 2.0 T. Animals were treated with diltiazem (200 [mu]g/kg intravenous bolus of drug followed by a 15 [mu]g/kg/min continuous intravenous infusion, n = 10) or by an equal volume of saline (n = 6). The left circumflex artery was occluded and reperfused using a reversible snare while electrocardiogram-gated spectra were accumulated. Levels of phosphocreatine were decreased during occlusion in both groups; however, this decrease was attenuated in the diltiazem treated animals compared to control (in relative percent area: 7.8 +/- 1.0 to 2.5 +/- 0.5, p p p p p = NS). During ischemia there was a trend toward attenuation of intracellular acidosis in the diltiazem group; however, this trend did not reach statistical significance. These data indicate that diltiazem provides a protective effect on myocardial high-energy phosphate metabolism during regional ischemia and reperfusion in the intact animal.

Published
2006

25. Evaluation of myocardial viability following ischemic and reperfusion injury using phosphorus 31 nuclear magnetic resonance spectroscopy in vivo

Author

Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich., USA; Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich., USA., Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich., USA; Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich., USA., Wroblewski, Lynette C., Aisen, Alex M., Swanson, Scott D., Buda, Andrew J., Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich., USA; Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich., USA., Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich., USA; Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich., USA., Wroblewski, Lynette C., Aisen, Alex M., Swanson, Scott D., and Buda, Andrew J.

Abstract

Recovery of myocardial high-energy phosphate (HEP) metabolism after coronary occlusion and reperfusion may vary with ischemic duration and may provide information about the extent of tissue viability. To evaluate the differences between varying durations of ischemia and to attempt to identify metabolic indexes of salvaged viable tissue, intact New Zealand white rabbits underwent either 30 (group 1; n = 8) or 60 (group 2; n = 8) minutes of coronary occlusion followed by reperfusion. HEP metabolism was evaluated with cardiac gated phosphorus 31 (31P) nuclear magnetic resonance (NMR) spectroscopy with a 2.0 T spectrometer. While similar HEP changes were observed during ischemia in both groups, differences in HEP recovery between groups were seen following reperfusion. Group 1 animals demonstrated a gradual decrease in inorganic phosphates (PI) (p p = ns versus baseline), and a gradual increase of adenosine triphosphate (ATP) to pre-ischemic levels. Group 2 animals had elevated levels of Pi (p p p p p r = 0.59, p R = 0.73, p 31P NMR spectroscopy may be useful in the evaluation of postischemic myocardial viability.

Published
2006

26. MRI in osteoarthritis of the hip: Gradations of severity

Author

Department of Radiology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA, Department of Rheumatology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA, Li, King C., Higgs, Jay, Aisen, Alex M., Buckwalter, Kenneth A., Martel, William, McCune, William Joseph, Department of Radiology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA, Department of Rheumatology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA, Li, King C., Higgs, Jay, Aisen, Alex M., Buckwalter, Kenneth A., Martel, William, and McCune, William Joseph

Abstract

In a prospective study, 10 patients with well-documented osteoarthritis (O.A.) of the hips were imaged using spinecho pulse sequences (TR = 0.5 to 1.5 s and TE = 28 to 60 ms). After analyzing the changes observed, an MR grading system for assessing severity of O.A. in the hips was developed. Using this grading system and an established grading system for osteoarthritis using roentgenograms (both systems use grades 0-4), two radiologists independently graded the MR studies and plain films separately, twice. The roentgenogram grading system was more accurate in predicting symptoms in the more severe cases, whereas the MR grading system was slightly more useful in the less severe cases. Our results show that MR can demonstrate a spectrum of changes of O.A. in the hips. Its ability to directly image articular cartilage makes it a powerful research and clinical tool.

Published
2006

27. Visualization of myocardial infarction and subsequent coronary reperfusion with MRI using a dog model

Author

Department of Radiology, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA; Cardiology Division, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA., Department of Internal Medicine, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA, Cardiology Division, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA; Department of Radiology, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA., Aisen, Alex M., Buda, Andrew J., Zotz, Rainer J., Buckwalter, Kenneth A., Department of Radiology, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA; Cardiology Division, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA., Department of Internal Medicine, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA, Cardiology Division, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA; Department of Radiology, University of Michigan Hospitals, Ann Arbor, Michigan 48109, USA., Aisen, Alex M., Buda, Andrew J., Zotz, Rainer J., and Buckwalter, Kenneth A.

Abstract

Twelve anesthetized mongrel dogs underwent left thoracotomy with placement of a removable ligature around the left circumflex coronary artery. Following a 3 to 6 hour delay, ECG-gated spin-echo MRI was performed. The ligature was then removed reperfusing the heart, and after a 10-15 min period, MRI repeated. Finally, post-sacrifice images were obtained, and the hearts chemically stained for infarct evaluation. The MR images were subjectively and quantitatively evaluated for visibility of the endocardial border and of the injured myocardium, and for changes after reperfusion. The injured tissue was variably visible in vivo, the major limitation a result of motion blurring and artifact. The abnormal tissue was easily visible on MRI in 11 animals, and not clearly visible in one. The endocardial border was easily seen in 10 animals. The variation of calculated relaxation times was high for both normal and ischemic/infarcted myocardium in the beating hearts (normal: T1 = 566 +/- 288, T2 = 38 +/- 6; injured myocardium: T1 = 637 +/- 250, T2 = 41 +/- 12) in contrast, relatively stationary skeletal muscle measured in the same images had narrower ranges (T1 = 532 +/- 199, T2 = 28 +/- 2). Changes with reperfusion were seen, but not reliably. The infarcted or ischemic zones were easily visible on post-sacrifice images in all animals imaged. Post-sacrifice relaxation times were T1 = 564 +/- 69 msec, T2 = 39 +/- 3 msec for normal heart muscle, and 725 +/- 114, T2 = 47 +/- 5 for ischemic/infarcted tissue. We conclude that acute myocardial infarction can usually be detected by MRI, given a prior knowledge of its location. However, the technique is at present likely to be of only limited value clinically in the prospective diagnosis of acute myocardial infarction, though this may improve as technology advances. Finally, signal changes following reperfusion may be visible in some cases, but not reliably so.

Published
2006

28. Determination of left ventricular volumes and ejection fraction by nuclear magnetic resonance imaging

Author

Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich, USA; Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich, USA., Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich, USA; Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich, USA., Dilworth, Lee R., Aisen, Alex M., John Mancini, G.B., Lande, Ian, Buda, Andrew J., Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich, USA; Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich, USA., Cardiology Division, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Mich, USA; Department of Radiology, University of Michigan Medical School, Ann Arbor, Mich, USA., Dilworth, Lee R., Aisen, Alex M., John Mancini, G.B., Lande, Ian, and Buda, Andrew J.

Abstract

To determine the ability of nuclear magnetic resonance (NMR) imaging to assess left ventricular (LV) volumes and ejection fraction (EF), we studied 24 patients within 48 hours of single-plane LV angiography. In all patients, a transverse, single-plane NMR acquisition technique was employed with LV end-diastolic (ED) and end-systolic (ES) volumes (V) calculated by a modified area-length algorithm. In nine patients, a multialice acquisition technique was employed with LVEDV and LVESV calculated by a Simpson's rule algorithm. NMR-determined LVV and EF correlated reasonably well with angiographic values (LVEDV: r = 0.75; LVE8V: r = 0.90; and LVEF: r = 0.76). The singie-plane NMR technique significantly underestimated LVEDV (p p <0.05). This underestimation is likely related to off-axis imaging and to the geometric constraints of a single-plane algorithm. In comparing multislice NMR to angiographic data, no significant difference was demonstrated for LVEDV, LVESV, or LVEF. Thus, quantitation of LVV and EF with NMR is feasible, and comparison to angiographic volumes is similar to results reported from other noninvasive imaging modalities. Improvement in current acquisition techniques and software should result in further quantitative potential.

Published
2006

29. Detection and sizing of myocardial ischemia and infarction by nuclear magnetic resonance imaging in the canine heart

Author

Cardiology Division, Department of Internal Medicine, and Departments of Radiology, Surgery, and Physiology, University of Michigan Medical School, USA, Buda, Andrew J., Aisen, Alex M., Juni, Jack E., Gallagher, Kim P., Zotz, Rainer J., Cardiology Division, Department of Internal Medicine, and Departments of Radiology, Surgery, and Physiology, University of Michigan Medical School, USA, Buda, Andrew J., Aisen, Alex M., Juni, Jack E., Gallagher, Kim P., and Zotz, Rainer J.

Abstract

The usefulness of NMR imaging to size infarcted and hypoperfused, ischemic myocardium was assessed in 16 dogs which underwent coronary artery occlusion and reperfusion. During occlusion, technetium-99 microspheres were injected into the left atrium. Following death, the hearts were excised and underwent NMR imaging with a 0.35 tesla magnet, using multiple spin-echo pulse sequences. The epicardium of the heart was marked to indicate the level of the NMR cross-sectional tomographic image. The heart was subsequently breadloafed into 5 mm sections and the corresponding NMR cross-section was flagged for analysis. Autoradiography was performed to measure the hypoperfused, at-risk zone, and triphenyltetrazolium chloride staining was used to measure infarct size. For the flagged tomographic slice, the size of the NMR abnormality correlated well (r = 0.95), and was comparable to the actual hypoperfused, at-risk zone of the left ventricle. However, NMR estimates of infarct size correlated less well (r = 0.75) with the pathologic measure, and significantly overestimated actual infarct size (p 1 and T2 values were consistently increased (p <0.0005) in both the hypoperfused and infarct zones, compared to normal myocardium. We conclude that NMR imaging can detect acute myocardial ischemia and infarction, but overestimates infarct size and corresponds better to the area of hypoperfused, ischemic myocardium. In this excised canine heart occlusion-reperfusion model, the NMR abnormality corresponded best to the area including both infarction and the surrounding ischemic region.

Published
2006

38. Abdominal MR Imaging at 3.0 T

Author

Akisik, Fatih M., primary, Sandrasegaran, Kumaresan, additional, Aisen, Alex M., additional, Lin, Chen, additional, and Lall, Chandana, additional

Published
2007
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44. A multisite phase III study of the safety and efficacy of a new manganese chloride-based gastrointestinal contrast agent for MRI of the abdomen and pelvis

Author

Small, William C., primary, DeSimone-Macchi, Debra, additional, Parker, John R., additional, Sukerkar, Arun, additional, Hahn, Peter F., additional, Rubin, Daniel L., additional, Zelch, James V., additional, Kuhlman, Janet E., additional, Outwater, Eric K., additional, Weinreb, Jeffrey C., additional, Brown, Jeffrey J., additional, de Lange, Eduard E., additional, Woodward, Paula J., additional, Arildsen, Ronald, additional, Foster, Gregory S., additional, Runge, Val M., additional, Aisen, Alex M., additional, Muroff, Lawrence R., additional, Thoeni, Ruedi F., additional, Parisky, Yuri R., additional, Tanenbaum, Lawrence N., additional, Totterman, Saara, additional, Herfkens, Robert J., additional, Knudsen, John, additional, Laster, Jr., Robert E., additional, Duerinckx, Andre, additional, Stillman, Arthur E., additional, Spritzer, Charles E., additional, Saini, Sanjay, additional, Rofsky, Neil M., additional, and Bernardino, Michael E., additional

Published
1999
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