Diagnostics and Medical Technology Med Sci Monit, 2005: 11(5): M133-38 BACKGROUND power of MRI and CT is usually a few millimeters [11, 121, but a resolving power of soft tissues can be attained on the Uterine leiomyomas, which result from hyperplasia of uter- order of um with the DEl technique [13]. It has several ad- he smooth muscle tissues, is a common benign tumor. About vantages in the microscopic imaging of soft tissues such as 0%o of women of reproductive age will develop such leo- uterine leiomyomas, and is of very effective clinical investi- myomas[1]. They are often found during medical examina ative value in medicine. In this paper we investigate uter- tion or laparotomy for other diseases because they are often ine leiomyomas by the DEl method and various microstruc- asymptomatic In imaging diagnoses of uterine leiomyomas, tures are revealed. Image contrast is definitely increased as B-mode ultrasound is normally the initial and convention- different contrast mechanisms are used al examining method with which myomatous liquefaction, necrosis, segregation, and the like might be preferably ob MATERIAL AND METHODS served. It is a convenient, cheap, and multi-posture clinica diagnoses, but has definite limitations due to effects from Uterine leiomyoma samples were prepared at the Cancer ntestinal peristalsis and the changing in uterine leiomy- lospital of the Medical Center of Fudan University. The mas while the patient is being examined [2]. MRI (magnetic uterine leiomyoma was removed from a patient who under- resonance imaging)is an ideal diagnostic method in deter- went myomectomy. The shape of the uterine leiomyoma was lining the relation among the myomatous character, size, ellipsoid, with lubricous surface and some tenacity. After the configuration, and position in uterine space. It can show uterine leiomyoma was cut, its cross-section was a kind of silky the substantive, space-occupying lesion in the wall of uter- muscular layer with clear color. Degeneration could not be us,but it must usually work with a contrast agent [3]. Cr distinctly seen with the naked eye. The experimental samples (computed tomography) is also provided with some char- were taken from different regions of the uterine leiomyoma. acteristics of high spatial resolution, fine definition of im- One was adjacent to the edge of the uterine leiomyoma; the ge, and inner detection of the organs. It has the highest texture was soft and slightly red(sample 1). Sample Ill was resolution for adipose, blood, and calcification composition taken from the center of the uterine leiomyoma and [4]. However, the radiation dose of CT is high; the patient its texture was hard and it had a small portion of transparent must endure long-time radiation of high-intensity X-rays. state. Sample ll was taken from the region between samples In this way it carries a definite risk of injury to patients. CT I and Ill. The specimens were cut into 2-mm-thick sections should be used cautiously especially in young female pa- measuring 12x9 mm and fixed in 10%o buffered formalin. tients to avoid injury of reproductive organs. Figure I is the schematic setup for diffraction-enhanced im- Since the middle of the 1990s, a novel imaging technology aging. The important feature of the DEl setup is the analyz- has progressed: diffractionenhanced imaging(DEl). The er crystal [14]. X-rays from the synchrotron light source pass DEl method produces the image of an object with greater through a monochromator to be translated into monoen- sharpness and clarity than the traditional radiation meth- ergetic light. The monoenergetic X-rays traverse the sam- ods as a result of the combination of one or more contrast ple, undergo diffraction by the analyzer crystal, and are fi- echanisms: absorption, refractive gradient, and small-an- nally recorded by the detector. When the X-rays traverse the gle scattering rejection [5,6]. When the character and the sample, they are refracted by very small angles(in the m structure of a tissue is pathologically altered, its refractive croradian range) due to the tiny variations in refractive index also changes and forms a gradient of refraction in- dexes of the sample. The analyzer crystal can almost elimi- dexes. This gradient can be clearly seen in DEl images; con- nate the X-rays which are scattered within a large angle by quently, the microstructure and pathological changes in the sample. The X-rays emerging from the sample and hit- soft tissue can be distinctly shown in these images. Optical ting the analyzer crystal will satisfy the conditions for Bragg icroscope can usually display the surface, but not show diffraction only for a very narrow range of incident angles he internal structures of a sample, but the DEl technique (typically on the order of a few microradians). If the X-rays is capable of observing the internal microstructures of the hat have been refracted by the sample are within the an- sample because of the high penetrability of X-rays. In re- gular acceptance range of the analyzer, they will be diffract- cent years, DEI makes the conventional characterization of ed to the detector. Otherwise, if the X-rays that have been breast cancer clearer, and has latent applications in the ear- scattered by the sample fall outside this angular acceptance ly diagnosis of disease [7, 8] ange, they will not be reflected at all. The relationship of re- flectivity on incident angle is called the rocking curve [15]. The combination of DEl and CT, called DEF-CT, might have a The rocking curve is usually a triangular-shaped curve with articular relation to the pathological histology of cancer and a full width at half maximum(FWHM) of about several m has a great many applications in medicine [9]. In addition, al- roradians. Since the resulting refraction contrast originates though the intensity of synchrotron radiation is several orders from the slope of either shoulder of the triangular-shaped of magnitude higher than medical X-rays, the synchro otron rocking curve, it depends on the FWHM as well as the tun- based DEl method has a low risk of injury to patients because ing angle. We can obtain some images at different positions its exposure time is quite short and the absorbed radiation dose of the rocking curve by tuning the analyzer crystal. These should be low enough [10]. On the other hand, DEI images pictures contain absorption, refraction, and show high contrast for soft tissues, and the microstructure of small-angle scattering is rejected) information. In the DEl the inner part of organs can be clearly viewed as well. The te- experiment, two images must be obtained when the analyzer dium of pathological diagnoses, therefore, is avoided. is tuned to the FWHM positions on either side of the ng curve. These two images contain the same absorption in At present, uterine leiomyomas larger than I cm in diam- formation but opposite refraction information. We can sepa- eter can be shown with B-mode ultrasound. The resolving rate the different information from the two images through M134BACKGROUND Uterine leiomyomas, which result from hyperplasia of uter￾ine smooth muscle tissues, is a common benign tumor. About 20% of women of reproductive age will develop such leio￾myomas [1]. They are often found during medical examina￾tion or laparotomy for other diseases because they are often asymptomatic. In imaging diagnoses of uterine leiomyomas, B-mode ultrasound is normally the initial and convention￾al examining method with which myomatous liquefaction, necrosis, segregation, and the like might be preferably ob￾served. It is a convenient, cheap, and multi-posture clinical diagnoses, but has defi nite limitations due to effects from intestinal peristalsis and the changing in uterine leiomyo￾mas while the patient is being examined [2]. MRI (magnetic resonance imaging) is an ideal diagnostic method in deter￾mining the relation among the myomatous character, size, confi guration, and position in uterine space. It can show the substantive, space-occupying lesion in the wall of uter￾us, but it must usually work with a contrast agent [3]. CT (computed tomography) is also provided with some char￾acteristics of high spatial resolution, fi ne defi nition of im￾age, and inner detection of the organs. It has the highest resolution for adipose, blood, and calcifi cation composition [4]. However, the radiation dose of CT is high; the patient must endure long-time radiation of high-intensity X-rays. In this way it carries a defi nite risk of injury to patients. CT should be used cautiously especially in young female pa￾tients to avoid injury of reproductive organs. Since the middle of the 1990s, a novel imaging technology has progressed: diffraction-enhanced imaging (DEI). The DEI method produces the image of an object with greater sharpness and clarity than the traditional radiation meth￾ods as a result of the combination of one or more contrast mechanisms: absorption, refractive gradient, and small-an￾gle scattering rejection [5,6]. When the character and the structure of a tissue is pathologically altered, its refractive index also changes and forms a gradient of refraction in￾dexes. This gradient can be clearly seen in DEI images; con￾sequently, the microstructure and pathological changes in soft tissue can be distinctly shown in these images. Optical microscopes can usually display the surface, but not show the internal structures of a sample, but the DEI technique is capable of observing the internal microstructures of the sample because of the high penetrability of X-rays. In re￾cent years, DEI makes the conventional characterization of breast cancer clearer, and has latent applications in the ear￾ly diagnosis of disease [7,8]. The combination of DEI and CT, called DEI-CT, might have a particular relation to the pathological histology of cancer and has a great many applications in medicine [9]. In addition, al￾though the intensity of synchrotron radiation is several orders of magnitude higher than medical X-rays, the synchrotron￾based DEI method has a low risk of injury to patients because its exposure time is quite short and the absorbed radiation dose should be low enough [10]. On the other hand, DEI images show high contrast for soft tissues, and the microstructure of the inner part of organs can be clearly viewed as well. The te￾dium of pathological diagnoses, therefore, is avoided. At present, uterine leiomyomas larger than 1 cm in diam￾eter can be shown with B-mode ultrasound. The resolving power of MRI and CT is usually a few millimeters [11,12], but a resolving power of soft tissues can be attained on the order of µm with the DEI technique [13]. It has several ad￾vantages in the microscopic imaging of soft tissues such as uterine leiomyomas, and is of very effective clinical investi￾gative value in medicine. In this paper we investigate uter￾ine leiomyomas by the DEI method and various microstruc￾tures are revealed. Image contrast is defi nitely increased as different contrast mechanisms are used. MATERIAL AND METHODS Uterine leiomyoma samples were prepared at the Cancer Hospital of the Medical Center of Fudan University. The uterine leiomyoma was removed from a patient who under￾went myomectomy. The shape of the uterine leiomyoma was ellipsoid, with lubricous surface and some tenacity. After the uterine leiomyoma was cut, its cross-section was a kind of silky muscular layer with clear color. Degeneration could not be distinctly seen with the naked eye. The experimental samples were taken from different regions of the uterine leiomyoma. One was adjacent to the edge of the uterine leiomyoma; the texture was soft and slightly red (sample I). Sample III was taken from the center region of the uterine leiomyoma and its texture was hard and it had a small portion of transparent state. Sample II was taken from the region between samples I and III. The specimens were cut into 2-mm-thick sections measuring 12×9 mm2 and fi xed in 10% buffered formalin. Figure 1 is the schematic setup for diffraction-enhanced im￾aging. The important feature of the DEI setup is the analyz￾er crystal [14]. X-rays from the synchrotron light source pass through a monochromator to be translated into monoen￾ergetic light. The monoenergetic X-rays traverse the sam￾ple, undergo diffraction by the analyzer crystal, and are fi - nally recorded by the detector. When the X-rays traverse the sample, they are refracted by very small angles (in the mi￾croradian range) due to the tiny variations in refractive in￾dexes of the sample. The analyzer crystal can almost elimi￾nate the X-rays which are scattered within a large angle by the sample. The X-rays emerging from the sample and hit￾ting the analyzer crystal will satisfy the conditions for Bragg diffraction only for a very narrow range of incident angles (typically on the order of a few microradians). If the X-rays that have been refracted by the sample are within the an￾gular acceptance range of the analyzer, they will be diffract￾ed to the detector. Otherwise, if the X-rays that have been scattered by the sample fall outside this angular acceptance range, they will not be refl ected at all. The relationship of re- fl ectivity on incident angle is called the rocking curve [15]. The rocking curve is usually a triangular-shaped curve with a full width at half maximum (FWHM) of about several mi￾croradians. Since the resulting refraction contrast originates from the slope of either shoulder of the triangular-shaped rocking curve, it depends on the FWHM as well as the tun￾ing angle. We can obtain some images at different positions of the rocking curve by tuning the analyzer crystal. These pictures contain absorption, refraction, and extinction (i.e. small-angle scattering is rejected) information. In the DEI experiment, two images must be obtained when the analyzer is tuned to the FWHM positions on either side of the rock￾ing curve. These two images contain the same absorption in￾formation but opposite refraction information. We can sepa￾rate the different information from the two images through Diagnostics and Medical Technology Med Sci Monit, 2005; 11(5): MT33-38 MT34