Academic Appointments


Honors & Awards


  • Member, National Academy of Engineering
  • Member, Institute of Medicine

Professional Education


  • PhD, Stanford University, Electrical Engineering (1968)
  • MSc, Polytech Inst of Bklyn, Electrical Engineering (1953)
  • BS, CCNY, Electrical Engineering (1950)

All Publications


  • MRI: A Charmed Past and an Exciting Future JOURNAL OF MAGNETIC RESONANCE IMAGING Macovski, A. 2009; 30 (5): 919-923

    Abstract

    The invention and development of MRI took place under very desirable circumstances. Dr. Lauterbur, a distinguished NMR chemist, conceived of the basic idea. Once this concept was presented to the medical imaging community, a wonderful synergy developed between the two mature disciplines of NMR physical chemistry and medical imaging. This resulted in amazingly rapid progress and acceptance by the clinical community. This adventure is in sharp contrast to the history of x-ray imaging. This began with the accidental discovery of x-rays by Roentgen at the end of the 19th century. Unlike NMR, the basic x-ray mechanism was not understood and was mistakenly thought to not be an electromagnetic wave. MRI is now at an advanced stage where investigators study advanced hardware and software improvements. These studies include improved signal-to-noise ratio, resolution, and speed, which generally involve higher B(0). The high readout field results in numerous problems. These can be overcome by prepolarizing techniques using a high polarization field and a relatively low readout field.

    View details for DOI 10.1002/jmri.21962

    View details for Web of Science ID 000271247900001

    View details for PubMedID 19856404

  • Three-dimensional prepolarized magnetic resonance imaging using rapid acquisition with relaxation enhancement MAGNETIC RESONANCE IN MEDICINE Matter, N. I., Scott, G. C., Venook, R. D., Ungersma, S. E., Grafendorfer, T., Macovski, A., Conolly, S. M. 2006; 56 (5): 1085-1095

    Abstract

    Prepolarized MRI (PMRI) with pulsed electromagnets has the potential to produce diagnostic quality 0.5- to 1.0-T images with significantly reduced cost, susceptibility artifacts, specific absorption rate, and gradient noise. In PMRI, the main magnetic field cycles between a high field (B(p)) to polarize the sample and a homogeneous, low field (B(0)) for data acquisition. This architecture combines the higher SNR of the polarizing field with the imaging benefits of the lower field. However, PMRI can only achieve high SNR efficiency for volumetric imaging with 3D rapid imaging techniques, such as rapid acquisition with relaxation enhancement (RARE) (FSE, TSE), because slice-interleaved acquisition and longitudinal magnetization storage are both inefficient in PMRI. This paper demonstrates the use of three techniques necessary to achieve efficient, artifact-free RARE in PMRI: quadratic nulling of concomitant gradient fields, electromotive force cancelation during field ramping, and phase compensation of CPMG echo trains. This paper also demonstrates the use of 3D RARE in PMRI to achieve standard T(1) and fat-suppressed T(2) contrast in phantoms and in vivo wrists. These images show strong potential for future clinical application of PMRI to extremity musculoskeletal imaging and peripheral angiography.

    View details for DOI 10.1002/mrm.21065

    View details for Web of Science ID 000241761900018

    View details for PubMedID 17029228

  • Prepolarized magnetic resonance imaging around metal orthopedic implants MAGNETIC RESONANCE IN MEDICINE Venook, R. D., Matter, N. I., Ramachandran, M., Ungersma, S. E., Gold, G. E., Giori, N. J., Macovski, A., Scott, G. C., Conolly, S. M. 2006; 56 (1): 177-186

    Abstract

    A prepolarized MRI (PMRI) scanner was used to image near metal implants in agar gel phantoms and in in vivo human wrists. Comparison images were made on 1.5- and 0.5-T conventional whole-body systems. The PMRI experiments were performed in a smaller bore system tailored to extremity imaging with a prepolarization magnetic field of 0.4 T and a readout magnetic field of 27-54 mT (1.1-2.2 MHz). Scan parameters were chosen with equal readout gradient strength over a given field of view and matrix size to allow unbiased evaluation of the benefits of lower readout frequency. Results exhibit substantial reduction in metal susceptibility artifacts under PMRI versus conventional scanners. A new artifact quantification technique is also presented, and phantom results confirm that susceptibility artifacts improve as expected with decreasing readout magnetic field using PMRI. This proof-of-concept study demonstrates that prepolarized techniques have the potential to provide diagnostic cross-sectional images for postoperative evaluation of patients with metal implants.

    View details for DOI 10.1002/mrm.20927

    View details for Web of Science ID 000238823600019

    View details for PubMedID 16724303

  • Magnetic resonance imaging with T-1 dispersion contrast MAGNETIC RESONANCE IN MEDICINE Ungersma, S. E., Matter, N. I., Hardy, J. W., Venook, R. D., Macovski, A., Conolly, S. M., Scott, G. C. 2006; 55 (6): 1362-1371

    Abstract

    Prepolarized MRI uses pulsed magnetic fields to produce MR images by polarizing the sample at one field strength (approximately 0.5 T) before imaging at a much lower field (approximately 50 mT). Contrast reflecting the T(1) of the sample at an intermediate field strength is achieved by polarizing the sample and then allowing the magnetization to decay at a chosen "evolution" field before imaging. For tissues whose T(1) varies with field strength (T(1) dispersion), the difference between two images collected with different evolution fields yields an image with contrast reflecting the slope of the T(1) dispersion curve between those fields. Tissues with high protein content, such as muscle, exhibit rapid changes in their T(1) dispersion curves at 49 and 65 mT due to cross-relaxation with nitrogen nuclei in protein backbones. Tissues without protein, such as fat, have fairly constant T(1) over this range; subtracting images with two different evolution fields eliminates signal from flat T(1) dispersion species. T(1) dispersion protein-content images of the human wrist and foot are presented, showing clear differentiation between muscle and fat. This technique may prove useful for delineating regions of muscle tissue in the extremities of patients with diseases affecting muscle viability, such as diabetic neuropathy, and for visualizing the protein content of tissues in vivo.

    View details for DOI 10.1002/mrm.20910

    View details for Web of Science ID 000238051000017

    View details for PubMedID 16673360

  • Noise in MRI MAGNETIC RESONANCE IN MEDICINE Macovski, A. 1996; 36 (3): 494-497

    Abstract

    This study analyzes the signal-to-noise ratio (SNR) in magnetic resonance imaging. The factors that determine the SNR are derived starting from basic principles. The SNR, for a given object, is shown to be proportional to the voxel volume and the square root of the acquisition time. The noise generated by the body is derived using a cylindrical model and is shown to be proportional to the square of the radius and the square root of the length.

    View details for Web of Science ID A1996VE62700025

    View details for PubMedID 8875425

  • ON THE POTENTIAL USE OF STIMULATED POSITRON EMISSION (SPE) IN THE DETECTION AND MONITORING OF SOME BONE-DISEASES MEDICAL PHYSICS Benjamin, M., Macovski, A. 1980; 7 (2): 112-119

    View details for Web of Science ID A1980LE70700004

    View details for PubMedID 6966734

  • ULTRASONIC DIAGNOSTIC INSTRUMENTS SCIENCE Popp, R. L., Macovski, A. 1980; 210 (4467): 268-273

    Abstract

    The underlying physical principles and current limitations of diagnostic ultrasonic instruments are reviewed. Recently developed ultrasonic imaging devices using pulsed-reflected ultrasound are discussed in detail. These instruments transmit short trains of 1.5- to 10-megahertz sound. Echoes reflected from tissue are converted to electrical signals, which are presented on a display device to outline the contour of tissues and organs within the body. The physical resolution of the system is dependent on several design factors in addition to the transmitted sound frequencies. A resolution volume of approximately 1.5 by 3 by 4 millimeters is achieved optimally with commercially available systems operating at 2.25 megahertz. The various instrument designs are described in the context of clinical usage. Because the sound is diffracted, refracted, and reflected, tghe imaging considerations are different from those of x-ray imaging. Diagnostic devices based on the Doppler principle are distinguished from pulsed-reflected ultrasonic instruments.

    View details for Web of Science ID A1980KK76100007

    View details for PubMedID 7423186

  • ULTRASONIC-IMAGING USING ARRAYS PROCEEDINGS OF THE IEEE Macovski, A. 1979; 67 (4): 484-495
  • SCATTER CONSIDERATIONS IN FAN BEAM COMPUTERIZED TOMOGRAPHIC SYSTEMS IEEE TRANSACTIONS ON NUCLEAR SCIENCE STONESTROM, J. P., Macovski, A. 1976; 23 (5): 1453-1458
  • ENERGY-SELECTIVE RECONSTRUCTIONS IN X-RAY COMPUTERIZED TOMOGRAPHY PHYSICS IN MEDICINE AND BIOLOGY Alvarez, R. E., Macovski, A. 1976; 21 (5): 733-744

    Abstract

    All X-ray computerized tomography systems that are available or proposed base their reconstructions on measurements that integrate over energy. X-ray tubes produce a broad spectrum of photon energies and a great deal of information can be derived by measuring changes in the transmitted spectrum. We show that for any material, complete energy spectral information may be summarized by a few constants which are independent of energy. A technique is presented which uses simple, low-resolution, energy spectrum measurements and conventional computerized tomography techniques to calculate these constants at every point within a cross-section of an object. For comparable accuracy, patient dose is shown to be approximately the same as that produced by conventional systems. Possible uses of energy spectral information for diagnosis are presented.

    View details for Web of Science ID A1976CG72800002

    View details for PubMedID 967922

  • MEASUREMENT OF SOFT-TISSUE OVERLYING BONE UTILIZING BROAD-BAND ENERGY-SPECTRUM TECHNIQUES IEEE TRANSACTIONS ON NUCLEAR SCIENCE CHAN, J. L., Alvarez, R. E., Macovski, A. 1976; 23 (1): 551-554
  • IMPROVED DEPTH RESOLUTION IN CODED APERTURE GAMMA-RAY IMAGING SYSTEMS IEEE TRANSACTIONS ON NUCLEAR SCIENCE Steinbach, A., Macovski, A. 1976; 23 (1): 606-612
  • SPSE ANNUAL FALL SYMPOSIUM, SESSION-1 - ADVANCES IN RADIOGRAPHY, WASHINGTON, DC, 24 OCTOBER 1974 APPLIED OPTICS Macovski, A. 1975; 14 (1): 10-10
  • INTERNATIONAL WORKSHOP ON 3-DIMENSIONAL IMAGE RECONSTRUCTION TECHNIQUES, BROOKHAVEN-NATIONAL-LABORATORY, 16-19 JULY 1974 APPLIED OPTICS Macovski, A., Vest, C. M. 1975; 14 (2): 262-264
  • IMAGE-PROCESSING AT STANFORD NATURE Macovski, A. 1975; 257 (5524): 274-274
  • SELECTIVE MATERIAL X-RAY IMAGING USING SPATIAL FREQUENCY MULTIPLEXING APPLIED OPTICS Macovski, A., Alvarez, R. E., CHAN, J. L. 1974; 13 (10): 2202-2208

    Abstract

    A method is presented of encoding the transmission at specific regions of the x-ray energy spectrum onto a radiograph. A grating structure is placed in the x-ray beam that consists of alternate strips of material having different x-ray transmission spectra. The average spectral transmission of the two strips produces an image comparable to a conventional radiograph. The difference between the two transmission spectra produces an amplitude modulation of the grating pattern on the radiograph. When this grating pattern is decoded, through optical or scanning methods, it represents the transmission at the specific x-ray difference spectrum.

    View details for Web of Science ID A1974U298500016

    View details for PubMedID 20134661

  • ENVELOPE INTERFEROMETRY FOR LARGE-SCALE PROCESSING APPLIED OPTICS Macovski, A. 1974; 13 (11): 2689-2692

    Abstract

    An interferometry system is presented that is useful in large-scale measurements such as those of topographic maps. The envelope of a propagating wave is used to create the desired fringe patterns, representing range contours, through the interference of a light modulation function and an image modulation function. A number of variations are shown that either provide altitude contours or place the contour information on a spatial frequency carrier. This latter system offers the flexibility of electronic processing when the image is scanned. The comparison of contour patterns taken at different times provides an accurate indication of subtle surface deformations.

    View details for Web of Science ID A1974U657500059

    View details for PubMedID 20134756

  • GAMMA-RAY IMAGING SYSTEM USING MODULATED APERTURES PHYSICS IN MEDICINE AND BIOLOGY Macovski, A. 1974; 19 (4): 523-533

    View details for Web of Science ID A1974T815100011

    View details for PubMedID 4445224