ROBERT TEHPLE~ of l i v i n g c e l l s subjected t o ultrasonic vibrations. These references give

Transcription

1 222 A R E V I E V OF U L T R A S O N ~ CI ~ O R I Y I N B I O L O G Y AND ROBERT s MEDICINE^ TEHPLE~ The i n t e r e s t i n the use of ultrasonics a s a t o o l in evaluating livestock by animal s c i e n t i s t s prompts us t o take a closer look a t research along t h e same lines in other fields Ultrasonics, or hi&-frequency sound, employs t h e principle of piezoelectricity; t h a t is, t h e f a c t t h a t a vibrati n g c r y s t a l wiu develop an e l e c t r i c a l charge, and a l s o t h a t an e l e c t r i c a l charge w i l l s e t a c r y s t a l i n t o mechanical vibrations The sound waves so emitted by a quartz c r y s t a l a r e above the frequency which can be heard by t h e human ear, ie 18,OciO t o 20,000 cycles per second A look a t research i n t h e medical and biological f i e l d s may stimulate sme new ideas and approaches t h a t can be used i n animal research Research work i n t h e f i e l d of ultrasonics in biology and medicine i s r e l a t i v e l y new Work i n t h e f i e l d of ultrasonics a s a diagnostic t o o l i n medicine goes back o n l y t o the l a t e 1940's and early 1950's (Ludwig, 1950; Wild, 1951; and French, 1951) However, i n t e r e s t in ultrasonics i n t h e f i e l d of biology was demonstrated a s early a s 1927 by Wood and Loomis, who reported that f i s h, frogs, and other small animals could be k i l l e d by being placed i n a continuous ultrasonic radiation f i e l d Schmitt, Olson, and Johnson (1928) reported t h a t free-swimming larvae, spirostema, and paramecium could likewise be destroyed, Williams and Gaines (1960), using frequencies of 880 cycles per second, found t h a t a microorganism, E_ coli, could be k i l l e d, and t h a t t h e l e t h a l e f f e c t was probably due t o pressures within t h e c e l l s Harvey and Loomis (1931) made high-speed photomicrographs of l i v i n g c e l l s subjected t o ultrasonic vibrations These references give an indication of t h e i n t e r e s t t h a t developed for t h e use of ultrasonics i n c e l l destruction, k i l l i n g microorganisms, and other destructive uses t h a t l e d t o the development of ultrasonics a s a t o o l i n cleaning techniques, Gne of t h e i n t e r e s t i n g f u t u r e uses of ultresonics might be a greater development of dishwashers, instrument cleaners, and so f o r t h Indeed, maybe i n the f u t u r e we will even take a bath by subjecting ourselves t o high-frequency sound! Even though there i s a considerable amount of l i t e r a t u r e on t h e use of ultrasonics i n cleaning techniques, we w i l l not go i n t o t h a t area here Also, t h e use of ultrasonics i n physiotherapy and medical treatments w i l l not be reviewed, even though t h i s has been m e of t h e areas in ultrasonic research which t h e medical f i e l d has accepted most readily, 'Presented a t the 16th Reciprocal Meat Conference, S t i l l w a t e r, Oklahoma, June 11-13, 1S63 2Beef C a t t l e Research Branch, Animal Husbandry Research Division Knoxville, Tennessee ARS,

2 The successful application of the ultrasonic-pulse technique and t h e echo-ranging p r i n c i p l e t o underwater detection and ranging, and t o t h e l o c a l i z a t i o n of flaws i n metals (Firestone, 1946) prompted investigations by the rjaval Research I n s t i t u t e, 33ethesda, Maryland (Ludwig, 1950) concerning t h e use of an analogous technique f o r diagnostic purposes i n medicine and surgery Prior t o t h i s time, Schmidt e t a l, (1928) had investigated t h e frequencies of sound waves t h a t cause damage t o t i s s u e s In t h e i r work, they indicated t h a t continuous exposure t o vibrations of 8,000 t o 20,000 cycles per second produced t i s s u e damage They point out t h a t t h i s damage was produced a s a r e s u l t of continuous exposure r a t h e r than pulsed exposure, which i s t h e type used i n diagnostic work Porter (1939) and Gregg (1950) f e l t t h a t t h e damage produced may be due t o t h e heat produced or t o a chemical factor Porter reported diminished mental c a p a b i l i t i e s i n a wcman who was exposed t o 16,000 cycles per second of an ultrasonic source f o r an hour The e f f e c t s were reversible when she was removed from t h e ultrasonic chamber French, Wild, and Neal (1951) reported t h a t when frequencies were in the neighborhood of 15 mc, p e r second, modified t o pulse one-half millionth of a second, no damage m s caused, The vibrations were interrupted i n t h e apparatus so t h a t t h e experimental animal (rabbit) received 7 1/2 vibrations, skipped 1298 vibrations, and so on This had t h e double e f f e c t of (1) greatly reducing t h e power of t h e apparatus, and (2) permitting t h e heat produced by t h e vibrations t o d i s s i p a t e i t s e l f p r i o r t o the next series of vibrations, -I Wild and Neal (1951) reported no harmful e f f e c t s when t i s s u e s were subjected t o ultrasonic waves of t h e energy used i n ultrasonography They noted t h a t t i s s u e s of different texture gave d i f f e r e n t ultrasonograms Their work, as was t r u e f o r most of t h e other early work i n sonography, was of a single dimension,i e giving a depth penetration only, indicating echoes a t various depths where materials of d i f f e r e n t sound impedance or resistance were encountered T h i s type of technique has been referred t o a s t h e A scan, Values of t h e c h a r a c t e r i s t i c impedance of various t i s s u e s were calculated by Ludwig in 1950 These data were used t o calculate ref l e c t i o n coefficients a t interfaces, such a s those between dissimilar t i s sues and between foreign bodies and tissues, Sound velocity was measured i n c e r t a i n human and animal t i s s u e s Specific gravity of each t i s s u e was measured, and t h e c h a r a c t e r i s t i c acoustical impedance calculated frcm t h e velocity i n t e n s i t y data Sound velocity through t i s s u e has been measured a t frequencies of 125 and 25 mc, by Ludwig, using a pulsed method The e f f e c t of fiber d i r e c t i o n of t h e t i s s u e s on t h e sound velocity was i n v e s t i gated with beef muscle No difference was found i n energy values when the muscle was traversed perpendicular t o the long a x i s of t h e muscle bundle, as compared t o when it was transversed p a r a l l e l with t h e muscle bundles This work indicated t h a t t h e r e was v a r i a t i o n i n t h e velocity of sound waves between brain, l i v e r, kidney, and spleen of t h e dog and hog, and f o r beef muscle Wild (1950), working on an immediate post-mortem sample of small i n t e s t i n e of a dog, could determine t h e layers of t i s s u e, when t h e material v a s folded so t h a t t h e r e were no a i r interfaces between t h e layers He concluded t h a t t h e method can be applied t o t h e detection of changes i n t i s s u e density, and discussed application f o r the detection of accessible tumors French (1951) and French, Wild, and Neal (1951) examined t h e p o s s i b i l i t y of locating sub-cortical neoplasms, a t the time of surgery, without t h e use of brain needles The ultrasonic principle upon which t h e

3 224 experiment was based was t h a t high-frequency sound waves, when driven through t i s s u e s, a r e believed t o t r a v e l a t a r a t e proportional t o t h e tissue density and e l a s t i c i t y These sound waves were r e f l e c t e d by surfaces of density or e l a s t i c i t y change, The frequency used i n t h i s experiment was 15 mc, per second Their results indicated t h a t t h e texture of t h e neoplastic cerebral t i s s u e is such that response i s approximately twice tbt of normal cerebral t i s s u e ; t h a t sub-cortical neoplasms can be located i n t h e post-mortem material by this method; and t h a t pulsed ultrasonic vibrations of t h i s frequency produce no damage in cerebral hemispheres of experimental animals, H o ~ r yand B l i s s (1952), worhing with an ultrasonic device which gave a two-dimension impression, o r 'B" scan, showed t h a t t h e instrument was capable of making sof't t i s s u e s t r u c t u r e s v i s i b l e i n a manner which will be useful f o r diagnostic purposes, Working with fresh specimens of g a l l bladder and l i v e r from l i v i n g subjects, they noted t h a t their results were f a r superior t o those obtained when working with Formalin-fixed specimens They concluded t h a t hardened tissue apparently takes on difperent ultrasonic properties, Howry's device, which presents a p i c t u r e of t h e object r a t h e r than a wave, made i n t e r p r e t a t i o n of t h e d i f f e r e n t i a t i o n of materials e a s i e r, They obtained continuous p i c t u r e s of g a l l b l a d d e r, l i v e r, forearm, neck, leg, and other p a r t s of t h e body from l i v i n g subjects, Howry, S t o t t, and Bliss (1954) presented work t h a t indicated visualization of benign and malignant tumors was possible by the use of ultrasonics In t h e kidney tissue, t h e outline of a smooth c y s t wall v a s v i s i b l e on the cathode ray tube Ep vitrq examination of a f r e s h b r e a s t specimen, which contained cancer, Indicated that t h e i n t e r f a c e s between t h e normal tissue and t h a t of t h e cancer were v i s i b l e on t h e cathode ray tube Bnprovement i n e a r l i e r equipment ( H a m y e t a l a, 1955) resulted i n p i c t u r e s t h a t shared such anatomical s t r u c t u r e s in t h e neck a s nerves, a r t e r i e s, veins, f a s c i a l planes, and muscles, Such disease processes a s c i r r h o s i s and carcinoma of the l i v e r were a l s o shuwn!the author of t h i s review would 1We t o point out that; i n t e r p r e t a t i o n of the p i c t u r e s obtained f r c j m the neck by Howry is q u i t e d i f f i c u l t, and t h a t a thorough knowledge of t h e anatorny and t i s s u e s t r u c t u r e being studied i s absolutely imperative This i s t r u e in l i v e stock evaluation Work, as well a s in technical and medical examinations A hawledge of the shape, size, and related s t r u c t u r e s of t h e muscles i n t h e beef animal is highly important, i f accurate i n t e r p r e t a t i o n of r e s u l t s i s t o be obtained A review of t h e l i t e r a t u r e i n more recent years reveals t h a t the use of ultrasonics i s spreading t o a number of new areas of research in medical science Baum and Greenwood (1960) studied t h e application of sonar and radar techniques i n ophthamology, The equipment they use operates a t a frequency of 15 mc, per second, using a '93" scan type presentation They reported using it t o detect and visualize radiolucent foreign bodies and t m o r s within the o r b i t of t h e eye They indicated t h a t t h e foreign bodies were readily located by this method, even i n l a r g e amounts of blood Research is a l s o being c a r r i e d on in examining the o r b i t a l tracings o f the eye The Journal of the American Medical Association (1960) reported t h a t D r, B Sundun of Sweden, indicated use of ultrasound in determining

4 225 v i a b i l i t y of the f e t u s when abortion i s threatened The object of t h e work i s t o distinguish between a c y s t i c and s o l i d swelling i n t h e uterus Even though t h i s work i s s t i l l i n the research stage, Dr Sundun indicated t h a t p a s t tests promised t o y i e l d much useful information Willocks (1962) r e ported a study involving the measurement of t h e f e t a l head This work o f fers t h e p o s s i b i l i t y of studying the growth of t h e f e t a l head during the l a t t e r weeks of pregnancy They indicated t h a t measurements may be made repeatedly from t h e 30th t o t h e 32nd week on t o b i r t h It i s a l s o pointed out t h a t, f o r t h e measurements of t h e s i z e of t h e f e t a l head t o be accurate by t h e use of ultrasonics, measurements must be made within a short time of delivery Willocks a l s o indicates t h a t very useful information can be obtained i n r e l a t i o n t o breach presentation MacVicar (1962) indicated t h a t a l l cases of pregnancy which were threatened with abortion were routinely examined with ultrasonics Over 1000 cases have been examined; of which more than 200 have been cases of pregnancy The purpose of t h i s examination vas t o confirm pregnancy and exclude t h e p o s s i b i l i t y of a hydatidiform mole hydatidiform mole - i s c l i n i c a l l y d i f f i The p o t e n t i a l l y malignant tumor c u l t t o diagnose before the passage of v e s t i c l e s, and biological assay may be equivocal Bydrocephalus of t h e pre-parturition f e t u s has been detected MacVicarIs paper pictured ovarian cysts The author stressed t h a t these p i c t u r e s shown were selected and, t h a t it often takes a s many a s eight separate views before a diagnosis can be reached Donald (1962) studied t h e use of ultrasonics i n o b s t e t r i c s and gynecology He indicated t h a t t h e p i c t u r e s obtained were crude, but helped t o distinguish between encysted and f r e e f l u i d, between an i n t r a - u t e r i n e f e t u s and a hydatidiform mole, between a s o l i d honiogeneous tumor--like a fibroid--and a tumor of heterogeneous consistency--like an ovarian carcinoma, and between obesity and a s c i t e s From t h i s work, it has been demonstrated t h a t the measurement of t h e f e t a l head in utero can be done t o an accuracy of within 2 m a of a b i p a r i e t a l diameter The method used by Donald involved a s p e c i a l multiple-angle ccmpound sector scanning technique, which is an elaboration of established radar practices This provides a two-dimensional cross-sectional view of a body and either a longitudinal or traverse section, a s desired - -- The Journal of t h e American Medical Association (1961) discussed a method of diagnosing cardiac disease by means of an ultrasound echo device developed by Dr lhge Edler e t $1 This device measures movement of cardiac valves, which makes it possible for a doctor t o judge t h e type and extent of c e r t a i n cardiac valve diseases without operation This work i s s t i l l i n t h e research stage, but it appears t o have promise I Berlyne (1961) conducted research with ultrasonics i n r e n a l biopsy The insturment was used, as an a i d t o r e n a l biopsy, t o detect t h e depth and position of t h e kidney The ultrasonic device used i n t h i s research work was the "A" scan type, giving a s i n g l e dimension depth This work indicated t h a t determination of the lower pole of t h e r i g h t kidney was possible by t h i s technique An example of a considerable amount of ultrasonic work regarding encephalography and c r a n i a l examination vas shown by Taylor e t a l (1961) Their work indicated t h a t detection of t h e displacement of t h e midline s t r u c t u r e s i n t h e brain above t h e tentorium was possible Diagnostic value of the device was demonstrated i n acute head injury It has been especially --

5 226 noteworthy i n t h e d i f f e r e n t i a l diagnosis of acute cerebral vascular accidents, major a r t e r i a l occlusions being regularly distinguished from spaceoccupying hematomas A r a t h e r complete review of t h e work with ultrasonics fn biolbgi c a l and medical research by Frye (1958) indicated that ultrasound may cons t i t u t e a t o o l of considerable power f o r s e l e c t i v e l y disrupting i n t r a c e l l u l a r structures The forces involved, even i n an intense ultrasonic f i e l d, a r e not s u f f i c i e n t t o disrupt small molecules, but they may exert s u f f i c i e n t force on large molecular species t o break r e l a t i v e l y weak bonds This disruption of bonds can be expected t o d r a s t i c a l l y a f f e c t t h e subsequent behavior of the c e l l Fry@gives an example of Russian reports On t h e use of intense ultrasound, which destroyed a t l e a s t some types of malignant neoplasms in humans F'rye a l s o indicates t h a t a number of i n v e s t i g a t o r s have been developing methods of visualizing soft t i s s u e s t r u c t u r e s by r e f l e c t e d ultrasonic pulses, and indicates t h a t no other method, a t present, can y i e l d t h i s type of information Even though many problems remain f o r study i n t h i s field, in p a r t i c u l a r, t h e mechanics of r e f l e c t i o n of sound as r e l a t e d t o t h e type of t i s s u e structure, Frye indicates t h a t t h i s area of investigation contains p o s s i b i l i t i e s f o r tremendous advances in t h e near future Another area of ultrasonic research in biomedicine, indicated by Frye, i s that of elucidating micro-structures of cells Measurements of ultrasonic absorption c o e f f i c i e n t s of proteins in solution indicate t h a t absorption by these components may account f o r a large f r a c t i o n of the absorption in soft t i s s u e structures However, Frye concludes t h a t, unfortunately, research in medicine involving ultrasonics has not yet caught the imagination o f many investigators A review of l i t e r a t u r e of t h i s kind stimulates one t o v i s u a u z e how some of t h e work in the medical f i e l d might be applied t o animal sciences The work by animal s c i e n t i s t s in trying t o visualize f a t thickness, l o i n eye size, and other muscles through t h e use of ultrasonics i s f a i r l y w e l l known It i s encouraging t o read t h a t medical Workers feel t h a t they can measure t h e s i z e of t h e f e t a l head i n utero t o an accuracy of within 2 mm T h i s would give us some indication of the p o t e n t i a l accuracy with which we might be able t o measure various t i s s u e depths i n l i v e animals I - Reviewing the works of Willocks (1962) and MacVicar (1962) i n volved in determining pregnancy, stages of pregnancy, types of presentation, and the i d e n t i f i c a t i o n of malignant tumors, presents a v a s t opportunity for the use of t h i s device in livestock Feasibly, this could be a very helpful t o o l t o the reproduction physiologist, not only in determining pregnancy, but a l s o i n determining causes f o r non-retention of t h e fetus, a s well as non-pregnancy itself The use of ultrasonics by veterinarians in determining locations of tumors, cysts, ulcerated t i s s u e s, and so forth, a s well a s t h e very p r a c t i c a l idea of locating hardware in the l i v e animal, may have some r e a l p o t e n t i a l, The use of ultrasonics in identifying bydrocephalus in t h e f e t u s, a s well as post-parturition, might indicate a p o s s i b i l i t y f o r i t s use a s a diagnostic t o o l in genetic studies

6 227 From t h e standpoint of meats research, there may be an a d d i t i o n a l use of ultrasonics i n t h e estimation of kidney knob size, marbling of c e r t a i n muscles, and i n the study of t h e s i z e of bones The ideas by Frye (1958) concerning t h e use of ultrasound, a s a t o o l f o r selectively disrupting i n t r a c e l l u l a r structures, might have some p o s s i b i l i t y i n tenderness studies Since it has been shown i n some of t h e research reviewed i n t h i s paper t h a t c e r t a i n t i s s u e s have d i f f e r e n t responses t o ultrasound, it might be f e a s i b l e t o determine i f connective t i s s u e could be broken down with a c e r t a i n frequency of ultrasound without disturbing any other body t i s s u e s Indeed, it might be possible t o break down the f a t molecules so t h a t they could be r e absorbed by t h e body If t h i s were done selectively--just on t h e outside layer of f a t of t h e animal's body, f o r instance, leaving t h e marbling i n t h e meat--the consuming housewife would c e r t a i n l y be pleased! A t any r a t e, regardless of some of t h e exotic ideas t h a t I have presented here f o r t h e use of ultrasonics i n animal science, I believe it i s obvious from the research work already accomplished t h a t ultrasonics does have a potential LITERATURE: CITED Baum, G and I Greenwoad 1960 Ultrasound in ophthalmology Journal of Ophthalmology, 49:249 Berlyne, G M, 1961 Ultrasonics i n r e n a l b i o p s y : of kidney position Lancet, 2:750 American An a i d t o determfnation Brown, T G 1962 An explanation of t h e principles of ultrasonic echo sounding Proceedings, Royal Society of Medicine, 55:637 Donald, Ian 1962 Sonar: A new diagnostic echo-sounding technique i n o b s t e t r i c s and gynecology Proceedings, Royal Society of Medicine, 55: 637 Echo-sounder 1961 Journal of the American Medical Association, 178:1198 French, L A 1951 The experimental application of ultrasonics t o t h e l o c a l i z a t i o n of brain tumors Journal of Neurosurgery, 8:198 French, L A,, J J Wild, and D Neal 1951 by ultrasonic pulses Cancer, 4:342 Frye, W J 1958, Detection of cerebral tumors Biological and Medical Acoustics, 30:387 me 1950 Physiological Frye, W J, V J Wulff, D, Tucker, and F J factors involved i n ultrasonically-induced changes i n l i v i n g systems: I I d e n t i f i c a t i o n of non-temperature effects Journal of t h e Acoustical Society of America, 22:867 Gregg, E C, 2:1132 Jr 1950 Ultrasonics: Biological e f f e c t s Medical Physics,

7 228 Earvey, E N and A L Loomis 1931 High-speed photo-micrography of l i v i n g c e l l s subjected t o supersonic vibrations Journal of General Physiology, l5:147 Hany, D H and W R B l i s s 1952 Ultrasonic visualization of s o f t tissue structures of the body Journal of Laboratory and Clinical Medicine, 40:579 Howry, D H, 3 H Holmes, C R Cushman, and G J Posakony 1955 Ultrasonic visualization of l i v i n g organ6 and tissues Geriatrics, 10:123 H o w, D HI, D A S t o t t, and W R, Bliss 1954 The ultrasonic visualization of carcinoma of the breast and other s o f t t i s s u e structures Cancer, 7:354 Ludwig, G D 1950, The velocity of sound through t i s s u e s and the acoustical impedance of tissues, Journal of the Acoustical Society of America, 22 :862 MacVicar, John 1962 I l l u s t r a t i v e examples of ultrasonic echograms Proceedings, Royal Society of Medicine, 55:638 Porter, C, W 1939 Curious effects of ultrasound (cited by Gregg) California Engineering Schmidt, F C, A R Olson, and C H Johnson 1928 Effects of highfrequency sound waves on protoplasm Proceedings, Society of Experimental Biology, Taylor, J C, J A Newell, and Peter Karvounis 1961 diagnosis of i n t r a - c r a n i a l space occupying lesions Ultrasound t e s t i n g i n obstetrics and gynecology American Medical Association, 173:708, 1960 Ultrasonics i n t h e Lancet, 1:1197 Journal of the J 1950 The use of ultrasonic pulses f o r the measurement of biological tissues and the detection of t i s s u e density changes Surgery, 27:183 Wild, J Wild, J J and D Neal 1951 Use of high-frequency ultrasonic waves f o r detecting changes of texture i n l i v i n g tissues Lancet, 1:655 Willocks, James 1962 The use of ultrasonics i n cephalometry Royal Society of Medicine, 55:640 Proceedings, Williams, 0 B and N Gaines 1930 The b a c t e r i c i d i a l e f f e c t of highfrequency sound waves Journal of Infectious Diseases, 47:485 Wood, R W and A, L Loomis 1927 Physical and biological e f f e c t s of high-frequency sound waves Phil Mag, 4: 417

8 229 DR, RAIGEY: Thank you, Bob You can see t h a t Bob has expended a very large e f f o r t t o assemble a l l of t h i s material, and we certainly appreciate it, Bob Next, we would l i k e t o l e a r n something about the instrumentation used i n ultrasonic work To present a paper on t h i s topic, we a r e fortunate t o have with us Jim Davis of the University of Georgia, Jim has worked with D r Stouffer of Cornell and with t h e Branson Company i n helping t e s t and improve some of t h e instruments which a r e being used i n ultrasonic work Jim i s concentrating h i s e f f o r t s a t Georgia on l i v e animal-carcass evaluation, # 7% # #Si: 7% # S# # # # #