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Nuclear magnetic resonance imaging of the kidney
66
Magnetic
Resonance
Imaging
lattice and spin-spin relaxation times (T, and T2) were measured on samples of nodular and extranodular tissue from each patient. Increased T, and T, were observed for benign cold nodules, an increase in T, alone for nodules with increased uptake, and a wide fluctuation in T, and T, for multinodular goiters. The four cancers in the series did not show a distinctive proton NMR pattern in comparison with the other nodular structures studied. The results point to the feasibility of applying NMR techniques to the detection of thyroid disease. J. Nucl. Med. 23: 48; 1982 Nuclear Magnetic Resonance Imaging of the Kidney Hedvig Hricak, M.D., Lawrence Crooks, Ph.D., Phillip Shelson, M.D. and Leon Kaufman, Ph.D. Radiologic Imaging Laboratory, University of California, San Francisco, CA 94143 The role of nuclear magnetic resonance (NMR) imaging of the kidney was analyzed in 18 persons (6 normal volunteers, 3 patients with pelvocaliectasis, 2 with peripelvic cysts, 1 with renal sinus lipomatosis, 3 with renal failure, 1 with glycogen storage disease, and 2 with polycystic kidney disease). Ultrasound and/or computed tomography (CT) studies were available for comparison in every case. In the normal kidney distinct anatomical structures were clearly differentiated by NMR. The best anatomical detail was obtained with spin echo (SE) imaging, using a pulse sequence interval of 1,000 msec and an echo delay time of 28 msec. However, in the evaluation of normal and pathological conditions, all four intensity images (SE 500/28. SE 500/56, SE 1,000/28, and SE 1,000/56) had to be analyzed. No definite advantage was found in using SE imaging with a pulse sequence interval of 1,500 msec. Inversion recovery imaging, enhanced the differences between the cortex and medulla, but it had a low signal-to-noise level and, therefore, a suboptimal overall resolution. The advantages of NMR compared with CT and ultrasound are discussed, and it is concluded that NMR imaging will prove to be a useful modality in the evaluation of renal disease. Radiology 146: 425; 1983 Potential Hazards and Artifacts of Ferromagnetic Nonferromagnetic Surgical and Dental Materials Devices in Nuclear Magnetic Resonance Imaging
and and
Paul F. J. New, M.D.,’ Bruce R. Rosen, M.D.,’ Thomas J. Brady, M.D.,’ Ferdinand0 S. Buonanno, M.D.,* J. Philip Kistler, M.D.,’ C. Tyler Burt, Ph.D.,’ Waldo S. Hinshaw, Ph.D.,4 Jeffrey H. Newhouse, M.D.,’ Gerald M. Pohost, M.D.3 and Juan M. Taveras,
l Volume 2, Number
1, 1984
M.D.’ ‘Department of Radiology and the Services of *Neurology and ‘Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, MA and 4Technicare Corporation, Solon, OH The risks to patients with metal surgical implants who are undergoing nuclear magnetic resonance (NMR) imaging and the artifacts caused by such implants were studied. Twenty-one aneurysm and other hemostatic clips and a variety of other materials (e.g., dental amalgam, 14 karat gold) were used. Longitudinal forces and torques were found to be exerted upon 16 of the 21 clips. With five aneurysm clips, forces and torques sufficient to produce risk of hemorrhage from dislocation of the clip from the vessel or aneurysm, or cerebral injury by clip displacement without dislodgement were identified. The induced ferromagnetism was shown to be related to the composition of the alloys from which the clips were manufactured. Clips with lo-14% nickel are evidently without sufficient induced ferromagnetism to cause hazard. The extent of NMR imaging artifacts was greater for materials with measurable ferromagnetic properties, but metals without measurable ferromagnetism in our tests also resulted in significant artifacts. Dental amalgam and 14 karat gold produced no imaging artifacts, but stainless steels in dentures and orthodontic braces produced extensive artifacts in the facial region. Radiology 147: 139; 1983 The Effects of Nuclear Magnetic Patients with Cardiac Pacemakers
Resonance
on
William Pavlicek, M.S.,’ Michael Geisinger, M.D.,’ Lon Castle, M.D.,* Gregory P. Borkowski, M.D.,’ Thomas F. Meaney, M.D.,’ Bruce L. Bream, B.S.3 and Joe H. Gallagher, Ph.D.’ Departments of ‘Radiology and ‘Cardiology, The Cleveland Clinic Foundation, Cleveland and the 3Technicare Corporation, Solon, OH The effect of nuclear magnetic resonance (NMR) imaging on six representative cardiac pacemakers was studied. The results indicate that the threshold for initiating the asynchronous mode of a pacemaker is 17 gauss. Radiofrequency levels are present in an NMR unit and may confuse or possibly inhibit demand pacemakers, although sensing circuitry is normally provided with electromagnetic interference discrimination. Time-varying magnetic fields can generate pulse amplitudes and frequencies to mimic cardiac activity. A serious limitation to the possibility of imaging a patient with a pacemaker would be the alteration of normal pulsing parameters due to timevarying magnetic fields. Radiology
147: 149; 1983
Magnetic
Resonance
Imaging
lattice and spin-spin relaxation times (T, and T2) were measured on samples of nodular and extranodular tissue from each patient. Increased T, and T, were observed for benign cold nodules, an increase in T, alone for nodules with increased uptake, and a wide fluctuation in T, and T, for multinodular goiters. The four cancers in the series did not show a distinctive proton NMR pattern in comparison with the other nodular structures studied. The results point to the feasibility of applying NMR techniques to the detection of thyroid disease. J. Nucl. Med. 23: 48; 1982 Nuclear Magnetic Resonance Imaging of the Kidney Hedvig Hricak, M.D., Lawrence Crooks, Ph.D., Phillip Shelson, M.D. and Leon Kaufman, Ph.D. Radiologic Imaging Laboratory, University of California, San Francisco, CA 94143 The role of nuclear magnetic resonance (NMR) imaging of the kidney was analyzed in 18 persons (6 normal volunteers, 3 patients with pelvocaliectasis, 2 with peripelvic cysts, 1 with renal sinus lipomatosis, 3 with renal failure, 1 with glycogen storage disease, and 2 with polycystic kidney disease). Ultrasound and/or computed tomography (CT) studies were available for comparison in every case. In the normal kidney distinct anatomical structures were clearly differentiated by NMR. The best anatomical detail was obtained with spin echo (SE) imaging, using a pulse sequence interval of 1,000 msec and an echo delay time of 28 msec. However, in the evaluation of normal and pathological conditions, all four intensity images (SE 500/28. SE 500/56, SE 1,000/28, and SE 1,000/56) had to be analyzed. No definite advantage was found in using SE imaging with a pulse sequence interval of 1,500 msec. Inversion recovery imaging, enhanced the differences between the cortex and medulla, but it had a low signal-to-noise level and, therefore, a suboptimal overall resolution. The advantages of NMR compared with CT and ultrasound are discussed, and it is concluded that NMR imaging will prove to be a useful modality in the evaluation of renal disease. Radiology 146: 425; 1983 Potential Hazards and Artifacts of Ferromagnetic Nonferromagnetic Surgical and Dental Materials Devices in Nuclear Magnetic Resonance Imaging
and and
Paul F. J. New, M.D.,’ Bruce R. Rosen, M.D.,’ Thomas J. Brady, M.D.,’ Ferdinand0 S. Buonanno, M.D.,* J. Philip Kistler, M.D.,’ C. Tyler Burt, Ph.D.,’ Waldo S. Hinshaw, Ph.D.,4 Jeffrey H. Newhouse, M.D.,’ Gerald M. Pohost, M.D.3 and Juan M. Taveras,
l Volume 2, Number
1, 1984
M.D.’ ‘Department of Radiology and the Services of *Neurology and ‘Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, MA and 4Technicare Corporation, Solon, OH The risks to patients with metal surgical implants who are undergoing nuclear magnetic resonance (NMR) imaging and the artifacts caused by such implants were studied. Twenty-one aneurysm and other hemostatic clips and a variety of other materials (e.g., dental amalgam, 14 karat gold) were used. Longitudinal forces and torques were found to be exerted upon 16 of the 21 clips. With five aneurysm clips, forces and torques sufficient to produce risk of hemorrhage from dislocation of the clip from the vessel or aneurysm, or cerebral injury by clip displacement without dislodgement were identified. The induced ferromagnetism was shown to be related to the composition of the alloys from which the clips were manufactured. Clips with lo-14% nickel are evidently without sufficient induced ferromagnetism to cause hazard. The extent of NMR imaging artifacts was greater for materials with measurable ferromagnetic properties, but metals without measurable ferromagnetism in our tests also resulted in significant artifacts. Dental amalgam and 14 karat gold produced no imaging artifacts, but stainless steels in dentures and orthodontic braces produced extensive artifacts in the facial region. Radiology 147: 139; 1983 The Effects of Nuclear Magnetic Patients with Cardiac Pacemakers
Resonance
on
William Pavlicek, M.S.,’ Michael Geisinger, M.D.,’ Lon Castle, M.D.,* Gregory P. Borkowski, M.D.,’ Thomas F. Meaney, M.D.,’ Bruce L. Bream, B.S.3 and Joe H. Gallagher, Ph.D.’ Departments of ‘Radiology and ‘Cardiology, The Cleveland Clinic Foundation, Cleveland and the 3Technicare Corporation, Solon, OH The effect of nuclear magnetic resonance (NMR) imaging on six representative cardiac pacemakers was studied. The results indicate that the threshold for initiating the asynchronous mode of a pacemaker is 17 gauss. Radiofrequency levels are present in an NMR unit and may confuse or possibly inhibit demand pacemakers, although sensing circuitry is normally provided with electromagnetic interference discrimination. Time-varying magnetic fields can generate pulse amplitudes and frequencies to mimic cardiac activity. A serious limitation to the possibility of imaging a patient with a pacemaker would be the alteration of normal pulsing parameters due to timevarying magnetic fields. Radiology
147: 149; 1983