Articles

NON- INVASIVE IMAGING PROCEDURES IN MEDICAL PRACTICE

Prof. KAKARALA SUBBARAO

M.B.B.S.,M.S.,F.R.C.R.,F.A.C.R.,

Chairman

Medwin Hospitals

Hyderabad – 500 001.

            Since the discovery of x rays by Wilhelm Conrad Roentgen in November, 1986, x rays have been used extensively in the diagnosis of diseases[ effecting various systems of the body starting with location of metallic foreign bodies such as  bullets and sharp metallic objects to fractures of various bones. It has evolved into a major modality of diagnosis and is being extensively used in the diagnosis and management of disorders concerned with various specialities of medicine. In fact, today one can say “ The practice of medicine is the practice of radiology and imaging.’’

            During the first world war, the teachniques, technologies and equipment in radiography have undergone a grat changr so that contrast has improved, radiation protective measures have been implemented and oral and intravenous  contrast materials have been introduced. Even today barium sulfate is being used as a non- absorable contrast medium in the studay of gastrointestinal tract, introduced either orally or rectally. Whenever, soild contrast media are contraindicated such as in cases of intestinal obstructionsand perforations, water soluble media such as gastrograffin can be used. Similarly in the studay of urinary tract, intravenous iodine compounds are used and to combat the reactions, non-ionic media has been recently introduced in the past decade. Hysterosalpingography is being done for decades with water soluble contrast media. Similarly in the study of the spinal cord and contents of the spinal canal iodinated compounds, which are soluble in the cerebrospinal fluid are bring used as myelographic contrast media. With the introduction of non-ionic, iodine containing contrast media, the adverse reactions on the patients are minimised. In order to studay the deeper structures of the body conventional tomography was introduced in the early 40s but today with the introduction of computed axial tomography (CT), conventional tomography is being used less and less except in rere cases. Statistically in a general hospital, the utization of conventional radiology is maximum where as in speciality and superspeciality medcial centres hospitals the latest modlities of imaging namely ultrasonography, CT, MRI, angiography and radio nulides are being used. The non invasive imaging procedures include conventional rediography, ultrasonography, CT, MRI and radioactive isotopes with the help of a Gamma Camera. The invasive procedures include angiography, introduction of antegrade and retraodgrade catherers and interventional radiology.

            Considering system by system in the body in central nervous system, plain radiography of the skull is being taken except for detection of fractures and for localization of radipaque foreign bodies. In the study of disorders of spine, conventional radilogy still plays a mahor role and is being used extensively although to study the spinal canal and its contents CT and MRO are ideal investigative methods if available. Myelography is being used less and less. For disorders of head and neck, particularly for ear, nose and throat problems, conventional radiology is the primary secreeing method.

            With ragrads to the chest conventional radilogy is the gold standard and is being used extensively in all the primary, middle and tertiary care centres. C T has its own role since it depicts cross sectional images. The localization as well as characterization of the deper lesions in the lungs and pleura are obtained as lcear images by C.T. of late spiral C.T. has been inrouduced, the advantages being fast screening, high resolution and even the major and medium sized vessels supplying the various organs and extermitis can be visualized. Ultrasonography is another non invasive modality which is extensively used for pericadial and pleural lesions. The advantages of ultrasonography include simplicity of techniques, lack of exposure of ionizing radiation, case of performing at the bedside and lesser cost to the patient. The major advantage is that it is easier to dirrerentiate between solid and cystic structures. The best modality for mediastinal masses is CT although for cardiovascular strutures MR is replacing angiography. With a well developed software technology, MR angiography is being extensively used in tertiary care centres alomost replacing conventional angiography for the study of cardiovascular structures. In the study of pulmonary embolism, radio muclide study is best which includes both perfusion as well as diffusion techniques, Pulmonary angiography is being used rarely.

            In gastroenterology, for the study of upper G.I. tract, barium meal is best even today, although the number of barium meal studies have been reduced to 1/3 with the inroudction of endoscopy. However for the study of small bowel, barium meal Is being used extensively. In depicting the lisions of the colon, barium enema is again the gold standard although colonoscopy has reduced the number of barium studies of the colon. In the study of diseases of gall bladder, oral cholocystography has been completely replaced by ultrasonography. In the study of lesions of the liver, ultrasonography is being utilized to locate the abscess and other space occupying lesions.

            In the detection of lesions study of lower urinary tract, ultrasonography is being used replacing the retrograde type of urography. In the practice of Obstetrics and gynaecology ultrasonography has a major role job and is replacing the conventional methods. However, on occasion, hysterosaplingography is still being used. With the introduction of transvaginal and transerctal ultrasonography the study of female genital organs as well as male genitalia inluding prostrate are being studied incrasingly with  ultrasonography. Colour doppler ultrasonography is also non invasive and demonstrates the vascular supply of the normal as well abnormal structures. In perpheral vascular studies, venography and angiography are being replaced by doppler sonography.

            In onco-imaging CT,MRI, singly photon Enery Computing Tomography (SPECT), and postron emission tomography(PET) are being used to identify the spread of malignancy lically as well as systemically. Radio active isotope labelled monoclonal antibodies act as magic bullets in locating the primary and metastatic neoplasms and play an important role in the diagnosis and treatment of cancer.