1979, British Journal of Radiology, 52, 680-661
Proceedings of The British Institute of Radiology
NMR imaging* Abstracts of papers presented ata joint meeting of The British Institute of Radiology, The Institution of Electrical Engineers and the Institution of Electrical and Radio Engineers on November 16,1978 in the Faraday Room at The Institution of Electrical Engineers, Savoy Place, London WC2R OBL Imaging by nuclear magnetic resonance and its biomedical implications, by J. Mallard, J. M. S. Hutchison, W. Edelstein, M. Foster and R. Ling. NMR imaging at intermediate sizes, by E. R. Andrew, P. A. Bottomley, W. S. Hinshaw, G. N. Holland, W. S. Moore, C. Simaroj and B. S. Worthington. Human whole body imaging by NMR, by P. Mansfield. Physical limits to NMR imaging, by W. S. Hinshaw {no abstract received). IMAGING BY NUCLEAR MAGNETIC RESONANCE AND ITS BIO-MEDICAL IMPLICATIONS
By John Mallard, J. M. S. Hutchison, W. Edelstein, M. Foster and R. Ling Department of Bio-Medical Physics and Bio-Engineering, University of Aberdeen Nuclear magnetic resonance imaging of proton concentration within a tissue sample can be achieved by superimposing a magnetic field gradient upon the static magnetic field of an NMR spectrometer. In addition, by using pulsed techniques, the spin-lattice relaxation time, T i , can be imaged. A system operating at 1 -7 MHz is being built in Aberdeen using an air-cored magnet and a selective excitation technique to provide position data from adjacent lines, from which the image of transverse sections across any part of the human body can be built-up: relaxation time is displayed independently from proton concentration. Spatial resolution depends upon differences in T i from tissue to tissue and is expected to be better than 1 cm for trunk imaging. The T i over 50 different tissue types from animal and human post mortem samples have been measured at 24 MHz, and range from 1 50 to 800 m sec. The values are believed to be related to the closeness of the binding of water to macromolecules in the tissues. This five-fold range may lead to a significant improvement in the imaging of soft tissues and any pathological state which affects the water balance or binding of water within them, oedema being an example. While the imaging of tumours should prove possible, it is questionable whether this will be the major clinical use of the technique and its real contribution may be for conditions which, at present, are not amenable to other existing imaging procedures.
picture elements and have a resolution of 0-5 mm. Images have been obtained of thin sections of a live human hand, wrist and forearm, and of small animals (rabbit and rat). Good tissue discrimination is displayed with excellent correspondence to the actual anatomical features in sections subsequently cut (in the case of human images similar cadaver sections were cut for comparison) (Hinshaw etal., 1977; 1978; 1979). No radio frequency attenuation was evident in the images, and calculations suggest that for whole-body imaging this should not be too serious at frequencies below 10 MHz (Bottomley and Andrew, 1978). Current extension of proton NMR imaging to whole-body sizes is therefore practical in fields up to about 0-2 T. 19 F NMR images have also been obtained using phantoms and may have applications in conjunction with fluorinated pharmaceuticals and blood substitutes (Holland et ah, 1977); extension to 31P and other nuclei may also be of interest. Advantages of this method of medical imaging are its lack of hazard, the penetration of bony structures and its possible discrimination of pathological tissues through relaxation differences. Further details of the work are given in the references below. REFERENCES ANDREW, E. R., BOTTOMLEY, P. A., HINSHAW, W. S., HOLLAND, G. N., MOORE, W. S. and SIMAROJ, C , 1977.
NMR images by the multiple sensitive point method: application to larger biological systems. Physics in Medicine and Biology, 22, 97'1 -97'4. BOTTOMLEY, P. A., and ANDREW, E. R., 1978. RF magnetic
field penetration, phase shift and power dissipation in biological tissue: implications for NMR imaging. Physics in Medicine and Biology, 23, 630-643. HINSHAW, W. S., 1974. Spin mapping: the application of moving gradients to NMR. Physics Letters, 48A, 87-88. 1976, Image formation by nuclear magnetic resonance; the sensitive point method. Journal of Applied Physics, 47, 3709-3721. HINSHAW, W. S., ANDREW, E. R., BOTTOMLEY, P. A., HOLLAND, G. N., MOORE, W. S., and WORTHINGTON,
NMR IMAGING AT INTERMEDIATE SIZES
B. S., 1978. Display of cross sectional anatomy by nuclear magnetic resonance imaging. British Journal of
By E. R. Andrew, P. A. Bottomley, W. S. Hinshaw G. N. Holland, W. S. Moore, C. Simaroj
Radiology,
Department of Physics, and B. S. Worthington Department of Human Morphology and Radiology, University of Nottingham, University Park, Nottingham NG7 2RD Good quality proton NMR images of potential medical and biological usefulness have been produced by the multiple sensitive point method of NMR imaging (zeugmatography) (Andrew et ah, 1977', Hinshaw, 1974, 1976). An instrument has been developed which operates at 30 MHz for protons and has a specimen access of 8 cm diameter. A thin transverse section of the specimen, a few mm thick, is defined and scanned in 5 to 1 5 minutes. The images consist of 128 X 128 *Reprints of these abstracts may be obtained free on application to the Managing Editor, THE BRITISH JOURNAL OF RADIOLOGY, 32 Welbeck Street, London W1M 7PG (01-935 6867).
680
57,273-280.
1979. An in vivo study of the forearm and hand by thin section NMR imaging. British Journal of Radiology 52, 36-43. HINSHAW, W. S., BOTTOMLEY, P. A. and HOLLAND, G. N.,
1977. Radiographic thin section image of the human wrist by nuclear magnetic resonance. Nature, 270, 722-723. HOLLAND, G. N., BOTTOMLEY, P. A., and HINSHAW, W. S.,
1977.
91
F magnetic resonance imaging. Journal of Mag-
netic Resonance, 28, 1 33—1 36.
HUMAN WHOLE BODY IMAGING BY NMR
By P. Mansfield Department of Physics, University of Nottingham, Nottingham Progressing from our small scale nuclear magnetic resonance (NMR) line-scan imaging studies (Mansfield and Maudsley, 1976; 1977), which established the viability of using NMR
1979, British Journal of Radiology, 52, 681-682
Proceedings of The British Institute of Radiology to visualize anatomical detail in living fingers, we have now expanded the apparatus (principally the magnet) so that human whole body thin slice cross-sectional pictures can now be made. The first live line-scan image was produced with the full-scale apparatus earlier this year (Mansfield, et al., 1978). Current interests are concerned with detailed evaluation of NMR images obtained from cadaver tissue and some preliminary results of this work were presented. We have also used the apparatus to study tumorous whole breasts in operation samples following mastectomy. Results were presented which demonstrated for the first time, localization of a carcinoma in a whole breast (Mansfield et al., 1979). Line scan imaging, while being useful in general evaluation of the NMR imaging technique has severe limitations in imaging time for a given picture quality. Our interest is therefore turning more to ultra high-speed planar imaging methods (Mansfield and Pykett, 1978), which in terms of speed and picture quality seem to approach the optimum achievable from the point of view of information theory. Finally, the idea of using NMR to produce two dimen-
sional shadowgraphs as in normal X-ray techniques, was discussed and a preliminary result for a live human hand presented as a demonstration of its feasibility and possible usefulness. REFERENCES MANSFIELD, P. and MAUDSLEY, A. A., 1976. Planar and
Line-Scan Imaging by NMR Proc 19th Congress Ampere, Heidelberg, p. 247 (Groupment Ampere, Heidelberg, Eds. H. Brunner, K. H. Hauser and D. Schweitzer). 1977. Medical Imaging by NMR British Journal of Radiology, 50, 188-194. MANSFIELD, P., PYKETT, I. L., MORRIS, P. G., and COUP-
LAND, R. E., 1978 Human Whole Body Line Scan Imaging by NMR. British Journal of Radiology, 51, 921 — 922. MANSFIELD, P., MORRIS, P. G., ORDIDGE, R., COUPLAND, R. E., BISHOP, H., and BLAMEY, R., 1979. Carcinoma of
the Breast Imaged by NMR. British Journal of Radiology, 52, 242-243.
New methods of imaging in nuclear medicine Abstracts of papers presented at a joint meeting with the Royal College of Radiologists, the Royal Society of Medicine, section of Radiology and The British Institute of Radiology held on Thursday, February 15,1979 at Institute House, 32 Welbeck Street, London W1M 7PG. Longitudinal tomography, by M. J. Myers Emission computerized axial tomography, by W. I. Keyes Multiwire imaging devices, by J. E. Bateman Positron emission imaging, by T. Jones LONGITUDINAL TOMOGRAPHY
EMISSION COMPUTERISED AXIAL TOMOGRAPHY
By M. J. Myers
By W. I. Keyes
Department of Medical Physics, Hammersmith Hospital, London W12 OHS
Department of Bio-Medical Physics and Bio-Engineering, University of Aberdeen
The main features of longitudinal tomography that distinguish it from conventional imaging and from transverse tomography were outlined; for example, since all planes in the body are viewed simultaneously, their images interfere with each other and they can only be partially separated mathematically, as distinct from transverse tomography where each plane is separated exactly by physically limiting thefieldsof view. Two imaging devices were described and clinical examples from each presented. The one is a commercial instrument based on two scintillation cameras which are scanned over the body. Up to 12 longitudinal sections are produced by electronically repositioning the images on the crystal detectors to bring each section into focus. The other device is simpler and is based on a large solid-angle focused detector which scans each plane in turn. A method of separating the planes from each other by digitizing the images, calculating the contributions of other planes and then subtracting them from the plane of interest was also described. The direct production of longitudinal tomograms may, in the future, be superseded by constructing them from a series of contiguous transverse sections, but longitudinal tomography may find a place in fast dynamic sectional imaging using large area detectors and positron emitters.
Transverse-section emission tomography has provided an exciting opportunity to quantify with high spatial resolution the distribution of radionuclides in vivo. Using camera or scanner systems in conjunction with readily mavailable gamma-emitting radionuclides, particularly " T c , transverse section studies have been shown to enhance the value of conventional static imaging and to offer real quantitative potential. The technique was examined in terms of how and why it works, how different equipment is being used to the same ends, what sort of clinical results are being obtained and what the major problems and limitations are. The response of different systems to point, line and distributed sources was investigated as an illustration of how a system may be calibrated for measurement of absolute concentration of activity in terms of /*Ci per cm3. The relative sensitivity of the different systems, existing and proposed, was tentatively examined in terms of useful exposed crystal area.
Reprints of these abstracts may be obtained free on applicayion to the Managing Editor, BRITISH JOURNAL OF RADI-
OLOGY, 32 Welbeck Street, London W1M 7PG (01-935 6867)
681
Proceedings of The British Institute of Radiology
NMR imaging* Abstracts of papers presented ata joint meeting of The British Institute of Radiology, The Institution of Electrical Engineers and the Institution of Electrical and Radio Engineers on November 16,1978 in the Faraday Room at The Institution of Electrical Engineers, Savoy Place, London WC2R OBL Imaging by nuclear magnetic resonance and its biomedical implications, by J. Mallard, J. M. S. Hutchison, W. Edelstein, M. Foster and R. Ling. NMR imaging at intermediate sizes, by E. R. Andrew, P. A. Bottomley, W. S. Hinshaw, G. N. Holland, W. S. Moore, C. Simaroj and B. S. Worthington. Human whole body imaging by NMR, by P. Mansfield. Physical limits to NMR imaging, by W. S. Hinshaw {no abstract received). IMAGING BY NUCLEAR MAGNETIC RESONANCE AND ITS BIO-MEDICAL IMPLICATIONS
By John Mallard, J. M. S. Hutchison, W. Edelstein, M. Foster and R. Ling Department of Bio-Medical Physics and Bio-Engineering, University of Aberdeen Nuclear magnetic resonance imaging of proton concentration within a tissue sample can be achieved by superimposing a magnetic field gradient upon the static magnetic field of an NMR spectrometer. In addition, by using pulsed techniques, the spin-lattice relaxation time, T i , can be imaged. A system operating at 1 -7 MHz is being built in Aberdeen using an air-cored magnet and a selective excitation technique to provide position data from adjacent lines, from which the image of transverse sections across any part of the human body can be built-up: relaxation time is displayed independently from proton concentration. Spatial resolution depends upon differences in T i from tissue to tissue and is expected to be better than 1 cm for trunk imaging. The T i over 50 different tissue types from animal and human post mortem samples have been measured at 24 MHz, and range from 1 50 to 800 m sec. The values are believed to be related to the closeness of the binding of water to macromolecules in the tissues. This five-fold range may lead to a significant improvement in the imaging of soft tissues and any pathological state which affects the water balance or binding of water within them, oedema being an example. While the imaging of tumours should prove possible, it is questionable whether this will be the major clinical use of the technique and its real contribution may be for conditions which, at present, are not amenable to other existing imaging procedures.
picture elements and have a resolution of 0-5 mm. Images have been obtained of thin sections of a live human hand, wrist and forearm, and of small animals (rabbit and rat). Good tissue discrimination is displayed with excellent correspondence to the actual anatomical features in sections subsequently cut (in the case of human images similar cadaver sections were cut for comparison) (Hinshaw etal., 1977; 1978; 1979). No radio frequency attenuation was evident in the images, and calculations suggest that for whole-body imaging this should not be too serious at frequencies below 10 MHz (Bottomley and Andrew, 1978). Current extension of proton NMR imaging to whole-body sizes is therefore practical in fields up to about 0-2 T. 19 F NMR images have also been obtained using phantoms and may have applications in conjunction with fluorinated pharmaceuticals and blood substitutes (Holland et ah, 1977); extension to 31P and other nuclei may also be of interest. Advantages of this method of medical imaging are its lack of hazard, the penetration of bony structures and its possible discrimination of pathological tissues through relaxation differences. Further details of the work are given in the references below. REFERENCES ANDREW, E. R., BOTTOMLEY, P. A., HINSHAW, W. S., HOLLAND, G. N., MOORE, W. S. and SIMAROJ, C , 1977.
NMR images by the multiple sensitive point method: application to larger biological systems. Physics in Medicine and Biology, 22, 97'1 -97'4. BOTTOMLEY, P. A., and ANDREW, E. R., 1978. RF magnetic
field penetration, phase shift and power dissipation in biological tissue: implications for NMR imaging. Physics in Medicine and Biology, 23, 630-643. HINSHAW, W. S., 1974. Spin mapping: the application of moving gradients to NMR. Physics Letters, 48A, 87-88. 1976, Image formation by nuclear magnetic resonance; the sensitive point method. Journal of Applied Physics, 47, 3709-3721. HINSHAW, W. S., ANDREW, E. R., BOTTOMLEY, P. A., HOLLAND, G. N., MOORE, W. S., and WORTHINGTON,
NMR IMAGING AT INTERMEDIATE SIZES
B. S., 1978. Display of cross sectional anatomy by nuclear magnetic resonance imaging. British Journal of
By E. R. Andrew, P. A. Bottomley, W. S. Hinshaw G. N. Holland, W. S. Moore, C. Simaroj
Radiology,
Department of Physics, and B. S. Worthington Department of Human Morphology and Radiology, University of Nottingham, University Park, Nottingham NG7 2RD Good quality proton NMR images of potential medical and biological usefulness have been produced by the multiple sensitive point method of NMR imaging (zeugmatography) (Andrew et ah, 1977', Hinshaw, 1974, 1976). An instrument has been developed which operates at 30 MHz for protons and has a specimen access of 8 cm diameter. A thin transverse section of the specimen, a few mm thick, is defined and scanned in 5 to 1 5 minutes. The images consist of 128 X 128 *Reprints of these abstracts may be obtained free on application to the Managing Editor, THE BRITISH JOURNAL OF RADIOLOGY, 32 Welbeck Street, London W1M 7PG (01-935 6867).
680
57,273-280.
1979. An in vivo study of the forearm and hand by thin section NMR imaging. British Journal of Radiology 52, 36-43. HINSHAW, W. S., BOTTOMLEY, P. A. and HOLLAND, G. N.,
1977. Radiographic thin section image of the human wrist by nuclear magnetic resonance. Nature, 270, 722-723. HOLLAND, G. N., BOTTOMLEY, P. A., and HINSHAW, W. S.,
1977.
91
F magnetic resonance imaging. Journal of Mag-
netic Resonance, 28, 1 33—1 36.
HUMAN WHOLE BODY IMAGING BY NMR
By P. Mansfield Department of Physics, University of Nottingham, Nottingham Progressing from our small scale nuclear magnetic resonance (NMR) line-scan imaging studies (Mansfield and Maudsley, 1976; 1977), which established the viability of using NMR
1979, British Journal of Radiology, 52, 681-682
Proceedings of The British Institute of Radiology to visualize anatomical detail in living fingers, we have now expanded the apparatus (principally the magnet) so that human whole body thin slice cross-sectional pictures can now be made. The first live line-scan image was produced with the full-scale apparatus earlier this year (Mansfield, et al., 1978). Current interests are concerned with detailed evaluation of NMR images obtained from cadaver tissue and some preliminary results of this work were presented. We have also used the apparatus to study tumorous whole breasts in operation samples following mastectomy. Results were presented which demonstrated for the first time, localization of a carcinoma in a whole breast (Mansfield et al., 1979). Line scan imaging, while being useful in general evaluation of the NMR imaging technique has severe limitations in imaging time for a given picture quality. Our interest is therefore turning more to ultra high-speed planar imaging methods (Mansfield and Pykett, 1978), which in terms of speed and picture quality seem to approach the optimum achievable from the point of view of information theory. Finally, the idea of using NMR to produce two dimen-
sional shadowgraphs as in normal X-ray techniques, was discussed and a preliminary result for a live human hand presented as a demonstration of its feasibility and possible usefulness. REFERENCES MANSFIELD, P. and MAUDSLEY, A. A., 1976. Planar and
Line-Scan Imaging by NMR Proc 19th Congress Ampere, Heidelberg, p. 247 (Groupment Ampere, Heidelberg, Eds. H. Brunner, K. H. Hauser and D. Schweitzer). 1977. Medical Imaging by NMR British Journal of Radiology, 50, 188-194. MANSFIELD, P., PYKETT, I. L., MORRIS, P. G., and COUP-
LAND, R. E., 1978 Human Whole Body Line Scan Imaging by NMR. British Journal of Radiology, 51, 921 — 922. MANSFIELD, P., MORRIS, P. G., ORDIDGE, R., COUPLAND, R. E., BISHOP, H., and BLAMEY, R., 1979. Carcinoma of
the Breast Imaged by NMR. British Journal of Radiology, 52, 242-243.
New methods of imaging in nuclear medicine Abstracts of papers presented at a joint meeting with the Royal College of Radiologists, the Royal Society of Medicine, section of Radiology and The British Institute of Radiology held on Thursday, February 15,1979 at Institute House, 32 Welbeck Street, London W1M 7PG. Longitudinal tomography, by M. J. Myers Emission computerized axial tomography, by W. I. Keyes Multiwire imaging devices, by J. E. Bateman Positron emission imaging, by T. Jones LONGITUDINAL TOMOGRAPHY
EMISSION COMPUTERISED AXIAL TOMOGRAPHY
By M. J. Myers
By W. I. Keyes
Department of Medical Physics, Hammersmith Hospital, London W12 OHS
Department of Bio-Medical Physics and Bio-Engineering, University of Aberdeen
The main features of longitudinal tomography that distinguish it from conventional imaging and from transverse tomography were outlined; for example, since all planes in the body are viewed simultaneously, their images interfere with each other and they can only be partially separated mathematically, as distinct from transverse tomography where each plane is separated exactly by physically limiting thefieldsof view. Two imaging devices were described and clinical examples from each presented. The one is a commercial instrument based on two scintillation cameras which are scanned over the body. Up to 12 longitudinal sections are produced by electronically repositioning the images on the crystal detectors to bring each section into focus. The other device is simpler and is based on a large solid-angle focused detector which scans each plane in turn. A method of separating the planes from each other by digitizing the images, calculating the contributions of other planes and then subtracting them from the plane of interest was also described. The direct production of longitudinal tomograms may, in the future, be superseded by constructing them from a series of contiguous transverse sections, but longitudinal tomography may find a place in fast dynamic sectional imaging using large area detectors and positron emitters.
Transverse-section emission tomography has provided an exciting opportunity to quantify with high spatial resolution the distribution of radionuclides in vivo. Using camera or scanner systems in conjunction with readily mavailable gamma-emitting radionuclides, particularly " T c , transverse section studies have been shown to enhance the value of conventional static imaging and to offer real quantitative potential. The technique was examined in terms of how and why it works, how different equipment is being used to the same ends, what sort of clinical results are being obtained and what the major problems and limitations are. The response of different systems to point, line and distributed sources was investigated as an illustration of how a system may be calibrated for measurement of absolute concentration of activity in terms of /*Ci per cm3. The relative sensitivity of the different systems, existing and proposed, was tentatively examined in terms of useful exposed crystal area.
Reprints of these abstracts may be obtained free on applicayion to the Managing Editor, BRITISH JOURNAL OF RADI-
OLOGY, 32 Welbeck Street, London W1M 7PG (01-935 6867)
681
