Medical Imaging System BME 330 Lecture1

Part 1: Introduction Layout Definition of imaging and medical imaging Historical overview of medical imaging Trends of medical imaging Factors affecting the image characteristics

Objectives By the end of this part, the student should: Define and understand the general terms “image”, “imaging” and “medical imaging” Know the brief history of medical imaging. Define the different trends of medical imaging. Know the importance of medical imaging. Define the factors that affect the medical image characteristics Understand how can the physician read the medical image and extract some information to help making a proper diagnosis and/or plan for a treatment.

General Definition of Imaging? What is an image? is a representation of the external form of a person or thing in art. Nowadays, it is the recording the feature of an object for many engineering, medical, scientific, security and/or social purposes. How can an image be obtained? The feature of an object could be recorded manually in arts and most widely by imaging systems either cameras or any modality.

General Definition of Imaging? What is an imaging system? It is a system that sends some sort of energy to the object of interest and then receives the energy reflected or transmitted from the object to a film sensitive to this type of energy. The received energy carries data from the object which will appear on the film as difference in intensities. It may be as simple as that or may require some transformation mechanisms get such intensity differences. Recently, there are a wide variety of imaging systems that use sophisticated technologies to get more information about the objects being imaged.

General Definition of Imaging? According to the type of energy, the type of film will be. Nowadays, there are more advanced imaging system that utilized complicated technology to convey internal as well as external features

Medical Imaging: Definition Medical imaging is a process of taking an image for interior parts of the human body without surgery. This image provide information about the different properties (either anatomical and/or physiological) of the organs. The physician can use these information make proper diagnosis and plan for treatment. Many medical imaging modalities are currently available which allow to obtain images and valuable information for almost all parts of the human body. Examples of medical imaging modalities: x-ray imaging, CT, US imaging, MRI, …etc.

Medical Imaging: Definition Main methods of obtaining medical images Measuring the reflected radiations (eg. optical and ultrasound imaging) Measuring the transmitted radiations (eg. x-ray imaging) Measuring the emitted radiation (eg. magnetic resonance imaging)

Medical Imaging: Definition The image modality is chosen according to the organ and properties to be investigated. The degree of hazard is also an important factor when choosing certain imaging modality X-ray image Abdominal CT image US image MRI image

Medical Imaging: History Before the evolution of diagnostic equipment, doctors depend mainly on their perception (five senses: the faculties of sight, smell, hearing, taste, and touch) The upper image is from the Common Era (Abu Bakr Al-Razy 854 – 925 CE). The lower image is from the 19th century. Both were using their perception. So, there was a great need to surgery to diagnose and/or treat.

Medical Imaging: History X-Ray Imaging After he accidently noticed the effect of x-ray, Rontgen started some experiments to finally reach the image of the hand of his fiancée. Within less than 2 months, the technique was common and used in many applications specially in medicine imaging. Wilhelm Röntgen, 1895, Image from a circus Nothing was known about the hazards. Researches continued

Medical Imaging: History X-Ray Imaging Technological Developments lead to recent radiology Hot cathode x-ray tubes Rotating anodes Intensifying screens Image intensifiers Contrast agents and Angiography Computed and digital radiography CT

Medical Imaging: History Radon and Radon Transform, 1924 Calculation complexity and requirements With the advent of computer revolution, Hounsfield starts to apply Radon algorithm in 1971 In 1972, Hounsfield provides the CT prototype

Medical Imaging: History CT or CAT scan Development of CT CT images Now

Medical Imaging: History US Imaging: Sonography Was used in military purposes and used in medicine since 1942 by the American George Ludwig The first medical ultrasonography system was suggested in 1952

Medical Imaging: History US Imaging: Sonography: Real time imaging 1953

Medical Imaging: History Sonography today: 3D, 4D, color coding and elastography

Medical Imaging: History Nuclear magnetic Resonance discovered by the Nobel prize's Bloch and Purcell in 1945. They describe its physics and mathematics in 1946

Medical Imaging: History Paul Lauterbur and the MRI 1973 In 1973, with the computer advancement, Lauterbur applied the theory and mathematics of NMR done by Bloch and Purcell to record the first MRI image.

Medical Imaging: History High quality MR images in 1975 Ernest and utilizes the Fourier transform to reconstruct

Medical Imaging: History Whole body MR image in 1977 Damadian and the first whole body MRI

Medical Imaging: History Ultrafast MRI, 1977 Mansfield and the acquisition of the ultra-fast MR image in 1977

Medical Imaging: History MRI today

Medical Imaging: History PET & SPECT PET and SPECT  are nuclear medicine imaging techniques which provide metabolic and functional information unlike CT and MRI. They have been combined with CT and MRI to provide detailed anatomical and metabolic information.

Medical Imaging: History Optical Imaging The optical imaging was utilized as early as the era of the Arabian, Abulkasim (936-1013.) The first clinical laparoscope was used in 1901. Recently, there are many optical imaging modalities:

Medical Imaging: History Optical Imaging OCT and Fundus Camera Photoacoustic imaging

Medical Imaging: Trends Trends in medical imaging: development

Medical Imaging: Trends Functional Classification of Medical Imaging Anatomical imaging Vascular imaging Physiological imaging Imaging concentration of chemical composition Imaging for surgical aids

Medical Imaging: Trends Anatomical Imaging: Give the anatomical features of the imaged organ or part. The doctors can compare the image to actual anatomy and decide the diagnosis

Medical Imaging: Trends Anatomical Imaging: Useful for the noninvasive detection of pathologies

Medical Imaging: Trends Anatomical Imaging: Whole body imaging to get an overall report The spread of cancer for example

Medical Imaging: Trends Anatomical Imaging: Calculation of age of fetus

Medical Imaging: Trends Anatomical Imaging: 3D reconstruction

Medical Imaging: Trends Vascular Imaging:

Medical Imaging: Trends Vascular Imaging: 3D reconstruction Virtual catheterization for diagnosis

Medical Imaging: Trends Vascular Imaging: Color Doppler Blood flow measurement: Colored Doppler Red and blue indicates the direction of blood flow (diagnosis)

Medical Imaging: Trends Physiological Imaging: Not just an anatomical imaging Indicates whether an organ works normally or not. Example: 𝛾 𝑐𝑎𝑚𝑒𝑟𝑎→𝑡ℎ𝑦𝑟𝑜𝑖𝑑 𝑔𝑙𝑎𝑛𝑑 𝑎𝑐𝑡𝑖𝑣𝑖𝑡𝑦 (𝐼𝑜𝑑𝑖𝑛𝑒 𝑢𝑝𝑡𝑎𝑘𝑒)

Medical Imaging: Trends Physiological Imaging: Example: Understanding how the brain work Take some slices, repeat along the time (sequence) Record changes during certain activity and at rest and create a colored map

Medical Imaging: Trends Imaging the concentrations of chemical composition Noninvaisve measurement of the concentrations of different substances inside the tissue

Medical Imaging: Trends Imaging the concentrations of chemical composition More about the brain Concentration of certain chemical composition and the relation to the activity Choline Choline /creatinine Concentration spectra

Medical Imaging: Trends Imaging for surgical aids Before surgery to investigate

Medical Imaging: Trends Imaging for surgical aids During surgery to guide MRI designed for surgical purposes Cath. Lab

Medical Imaging: Trends Imaging for surgical aids Biopsy (somesort of surgical intervention) US beast biopsy US thyroid biopsy MRI brain biopsy

Factors Affecting the Image Characteristics Factors associated with the imaging system: Image c/c vary according to the type of radiation: optical (visible, or IR), US, X-rays, NMR Mode of detected radiation: reflection, transmission or emission Intensity, coherency and collimation of the radiation Sensitivity of sensors and transducers Quality of processing elements (amplifiers, ADC, filters,..etc) Environmental conditions: Interference • Temperature Properties of imaged tissue Density • Flexibility • Chemical composition • Temperature Magnetic resonance Velocity of moving tissue (blood and blood components)

Medical Image Characteristics Important notes Clinician make diagnosis based on the looks of the images Assuming that we got a number of images from same equipment, under same imaging conditions and for same patient (same tissue), then the image looks may change with the: changes in shape, for example enlargement or shrinkage of a particular structure, changes in image intensities within that structure compared to normal tissue and/or the appearance of features such as lesions which are normally not seen.

Medical Image Characteristics Important notes: So, image quality is a very important factor for proper diagnosis A full diagnosis may be based upon information from several different imaging modalities, which can be correlative or additive in terms of their information content. Improvement in medical imaging systems is continuously done to produce high quality images: instrumentation improvement and image processing Images are now saved and processed digitally