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Imaging techniques and tumor diagnosis: Introductory remarks
Biomed & Phrmocoher 0 Elscvicr, Paris
(1993)
47,241-243
241
Imaging techniques: PET in oncology
IMAGING TECHNIQUES REMARKS.
H.S.Raflaele.
AND TUMOR DIAGNOSIS:
INTRODUCTORY
Centro Medico Respighi. Milan, Italy.
Alter Roenlgen’s discovery over 50 years ago, the radiologist had been using simple and ripetilive techniques which were eventually improved in the late seventies. These new methods produced images based upon physical concepts often hard to understand. This technological change Completely revolutioned Ihe radiologist’s msthodoloav. makina him the ‘Patholooist 01 the livina oatient’. In fact. it iaonly the- body morphology”which more oG;n represents the conneclion between traditional radiologic imaging and the images obtained with the new machines. These ones produce excellent results. especially in demonstrating pathological processes characlerized by structural subversion. Among the new diagnostic techniques having success in the last 20 years. the most important is certainly echography (ultrasonography). Ultrasound issues from a thin quartz layer spread in straight lines into human body where they gradually become lainler due to absorption and reflection phenomena occurring when passing through lissue with different acoustic impedence. In traditional radiology information is given by the ‘residual energy’ left by x-ray alter passing through the examined object, while in echotomography reflected energy Is recorded. Threrefore echography can always and easily distinguish a solid, echogenic Stucture from a Ilquid. anechogentc and completely transparent one. As regards digital techniques, they are becoming more and more widely used. Computed tomography (CT) and digital angiography (DA) were the lirsl to be used, but technological progress leads us expect in the near future, digital transformation of all traditional techniques. with consequent improved diagnostic accuracy and much more reliable interpretation. Alter Roentaen’s discoverv. CT has been riahtlv considered Ihe most important r&odiagnostic iivention. so that
radiotherapy by reproducing the same cornpoled imaging, the isodose curves, which consider both the dimension of irradiation field and the density of tiisue passed lhrough by x-rays. Nuclear Magnetic Resonance (NMR) appeared long after TC. but it was really discovered in 1946 by physicists from Standlord University and, at the same period by Harvard University physicists. But the interest of NMR in medicine was awakened alter lhe discovery of R.Damedian that tumor tissues have much longer relaxing times (which are expression of the aggregative condition of Ihe substance) than those of normal tissues. With the possibility 01 spatially localizing eleclromagnetic resonance signals in the system it was logical then to obtain human body scannings by using reconstructive method similar to those utilized in CT. Even if on the surface NMR images seem similar to CT ones, data resulting from this new technique are completely different. In fact in CT discrimination among different tissues end between normal and pathological tissues is based on the difference in attenuation of x-rays passing through the same tissues and hence on different densities and on dilfrent atomic numbers of organic substances. On the other hand, in NMR the signals coming from tissues placed in a very intense magnetic field and exposed to electromagnetic radiofrequency impulses, depend on the chemical structure and the atomic molecular stale of aggregation of the examined organic material. The main peculiarity.of NMR imaging is the discrimination among the dillerent tissues in such a precise way thal it generally avoids having to use contrast media, which are on the conlrary necessary in traditional radiology and CT. A mention is also due to positron tomography, the only externally bloodless method which makes it possible lo perform accurate investigations on the regional metabolism of every tissue and In oariicular 01 heart and brain. Finallv. some recent aoolicatton of iadioisotopes in tumor diagnosis-and research t&#e to be remembered.
(1993)
47,241-243
241
Imaging techniques: PET in oncology
IMAGING TECHNIQUES REMARKS.
H.S.Raflaele.
AND TUMOR DIAGNOSIS:
INTRODUCTORY
Centro Medico Respighi. Milan, Italy.
Alter Roenlgen’s discovery over 50 years ago, the radiologist had been using simple and ripetilive techniques which were eventually improved in the late seventies. These new methods produced images based upon physical concepts often hard to understand. This technological change Completely revolutioned Ihe radiologist’s msthodoloav. makina him the ‘Patholooist 01 the livina oatient’. In fact. it iaonly the- body morphology”which more oG;n represents the conneclion between traditional radiologic imaging and the images obtained with the new machines. These ones produce excellent results. especially in demonstrating pathological processes characlerized by structural subversion. Among the new diagnostic techniques having success in the last 20 years. the most important is certainly echography (ultrasonography). Ultrasound issues from a thin quartz layer spread in straight lines into human body where they gradually become lainler due to absorption and reflection phenomena occurring when passing through lissue with different acoustic impedence. In traditional radiology information is given by the ‘residual energy’ left by x-ray alter passing through the examined object, while in echotomography reflected energy Is recorded. Threrefore echography can always and easily distinguish a solid, echogenic Stucture from a Ilquid. anechogentc and completely transparent one. As regards digital techniques, they are becoming more and more widely used. Computed tomography (CT) and digital angiography (DA) were the lirsl to be used, but technological progress leads us expect in the near future, digital transformation of all traditional techniques. with consequent improved diagnostic accuracy and much more reliable interpretation. Alter Roentaen’s discoverv. CT has been riahtlv considered Ihe most important r&odiagnostic iivention. so that
radiotherapy by reproducing the same cornpoled imaging, the isodose curves, which consider both the dimension of irradiation field and the density of tiisue passed lhrough by x-rays. Nuclear Magnetic Resonance (NMR) appeared long after TC. but it was really discovered in 1946 by physicists from Standlord University and, at the same period by Harvard University physicists. But the interest of NMR in medicine was awakened alter lhe discovery of R.Damedian that tumor tissues have much longer relaxing times (which are expression of the aggregative condition of Ihe substance) than those of normal tissues. With the possibility 01 spatially localizing eleclromagnetic resonance signals in the system it was logical then to obtain human body scannings by using reconstructive method similar to those utilized in CT. Even if on the surface NMR images seem similar to CT ones, data resulting from this new technique are completely different. In fact in CT discrimination among different tissues end between normal and pathological tissues is based on the difference in attenuation of x-rays passing through the same tissues and hence on different densities and on dilfrent atomic numbers of organic substances. On the other hand, in NMR the signals coming from tissues placed in a very intense magnetic field and exposed to electromagnetic radiofrequency impulses, depend on the chemical structure and the atomic molecular stale of aggregation of the examined organic material. The main peculiarity.of NMR imaging is the discrimination among the dillerent tissues in such a precise way thal it generally avoids having to use contrast media, which are on the conlrary necessary in traditional radiology and CT. A mention is also due to positron tomography, the only externally bloodless method which makes it possible lo perform accurate investigations on the regional metabolism of every tissue and In oariicular 01 heart and brain. Finallv. some recent aoolicatton of iadioisotopes in tumor diagnosis-and research t&#e to be remembered.