بسم الله الرحمن الرحيم Sudan university of science and technology College of medical radiological science Diagnostic radiologic technology department 4 th level Seminar about: Musculoskeletal System Ultrasound

Table of Contents:- Introduction Equipment Ultrasound physics Technique MSK ultrasound artifacts Musculoskeletal ultrasound benefits,limitations, and risks

Introductio n

The Problem of the study:- Bone diseases usually differentiated and confirmed by laboratory investigations which were invasive and expensive, so we need another non invasive, cheep and available tool for diagnosing.

Objectives:- To evaluate the roe of ultrasound in demonstrating musculoskeletal diseases. To identifying the a features of the new technology which applied by ultrasound. To demonstrate ultrasound findings in each pathology.

Introduction: Now a days radiology was grown faster and there were anew machines and applications were discovered routinely. The Sound: It is a mechanical wave that is transmitted through medium ( e.g., air, water, meta, or tissues).It is composed of three types: I.Ultrasound II.Hearing sound III.Infra sound

Ultrasound:- It is a mechanical energy transmitted through a medium by pressure wave.

History of US:- Its discovered by Jacques and Pierre Curie in 1880, was useful in transducers to generate and detect ultrasonic waves in air and water, also its frequencies greater than 20 kHz.

Common indications for MSK ultrasound:- assessment of ligament and/or tendon tears. investigation of articular disorders involving cartilage. assessment of bone for the presence of osteoporosis and/or cortical fractures. identification of joint effusions. evaluation of soft tissue masses. investigation of foreign bodies. investigation of vascular disease. sports injuries. palpable or suspected periarticular or intra-articular masses, rheumatologic disorders. to assess complications of surgical procedures.

Equip ment

Normal US machine is composed of the following :- I.display II.Keyboard III.Transducer IV.CPU V.Disk storage VI.Pulse controls VII.Printer VIII.Transmitter.

Types of Transducers Transducer : is small hand held device resembles a microphone attached to scanner by cord, TD convert electrical energy to acoustic energy,and acoustic energy to electrical signal (TD used as transmitter and detector). There is many types of transducer, the following are the most popular types:- I.Sector transducer II.Linear transducer III.Convex transducer

Cross section through Transducer

US physics

introduction The basis of all ultrasound applications are the detection and display the acoustic energy reflected from organ. Sound waves are transmitted as a series of alternating pressure waves with high pressure (compression) and low pressure (rarefaction) pulses. Infrasound waves Audible sound waves Ultrasound waves

Ultrasound waves propagating through body tissues a fluid (longitudinal wave) producing compression and rarefaction of conducting medium. Wavelength Frequency Propagation Propagation velocity

Techni que

How is the procedure performed for certain ultrasound examinations of the musculoskeletal system the patient may be seated on an examination table or a swivel chair. for other US exams, the patient is positioned lying face-up or face-down on an examination table. The radiologist or sonographer may ask you to move the extremity being examined or may move it for you to evaluate the anatomy and abnormality

Most US studies of infants and children are performed with the child lying on his or her back on the examination table, but other positions may be required. After you are positioned on the examination table, the radiologist or sonographer will apply a warm water-based gel to the area of the body being studied.

The transducer is placed on the body and moved back and forth over the area of interest until the desired images are captured.

Example for some techniques

The Hand

fracture of the base of the distal phalanx of the 5th finger Radiographic imageUltrasound image

the Elbow joint

Fracture of the proximal radius in a child.

KNEE JOINT

Patellar Fracture

MSK ultrasound artifacts

Artifacts in Musculoskeletal U/S A distortions or errors that affect in image acquisition and interpretation. Artifact may be related to:_ US beam characteristics errors ( beam width, anisotropy) attenuation errors ( acoustic shadowing and increased acoustic enhancement) may be associated with multiple echoes Reverberation). Anisotropy This artifact is more frequent and pronounced in echogenicity of the examined soft tissue when the US beam is not directed perpendicular to the examined anatomical tendons and ligaments due to their oblique course, and it can mimic pathology

Fig. 2 Anisotropy of the peroneal tendons.

Posterior acoustic shadowing artifact Posterior acoustic shadowing is an artifact that occurs when the US beam is high reflected, or more attenuation

ultrasound image of the Achilles tendon shows “clean” shadowing

Reverberation artifact  occur When examining two parallel highly reflective surfaces and have two type:- 1- Comet-tail artifact appears as a dense tapering trail of echoes This type of artifact occurs when there is a marked difference in acoustic impedances between an object and the surrounding tissues 2-Ring down artifact is a posterior reverberation artifact seen with scanning metal surfaces and has an appearance of a series of more continuous reflective echoes

ultrasound image of the proximal forearm

the lateral aspect of a knee in a patient with total knee arthroplasty

Musculoskeletal ultrasound benefits,limitations, and risks

Benefits: Most US scanning is noninvasive(no needles or injection). Occasionally, an US exam may be temporarily un comfortable, but it is almost never painful. US is widely available, easy to use and less expensive than other imaging modalities. US imaging extremely safe and dose not use any ionizing radiation. US scanning gives a clear picture of soft tissue that do not show up well on x-ray images. US provide real-time imaging, making it a good too for guiding minimally invasive procedures such as needle biopsies and fluid aspiration.

Patients with cardiac pacemakers and certain types of metallic implants or fragments in the body cannot be safely exposed to strong magnetic field required for MRI, however patients can safely receive US imaging. Because US images are captured in real time they can show the movement of soft tissue structures such as a tendon, joints or an extremity. US imaging is faster than MRI and dose not required the patient to remain completely still, allowing infants to be imaged without sedition. The hip joint of infants, un like those of adults, are largely made of cartilage.US is able to clearly see cartilage.

Limitations: US has difficulty penetrating bone and therefore can only see the outer surface of bony structures and not what lies within (infant) who have more cartilage. There are also limitation to the depth that sound waves can penetrate, there for deeper structure in larger patients may not be seen. It depends on personal skills.

Risks: FOR STANDERD DIAGNOSTIC US THERE ARE NO HARMFUL EFFECTS ON HUMANS

Presented by

References: Understanding Bone responses in B-mode Ultrasound Images and Automatic Bone Surface extraction using a Bayesian Probabilistic Framework Ameet Kumar Jain, Russell H. Taylor Computer Integrated Surgical Systems and Technology, Department of Computer Science, Johns Hopkins University, Baltimore, MD The registration of preoperative CT to intra-operative reality systems is a crucial step in Computer Assisted Orthopedic Surgery (CAOS). The intra-operative sensors include 3D digitizers, fiducials, X- rays and Ultrasound (US). Although US has many advantages over others, tracked US for Orthopedic Surgery has been researched by only a few authors. An important factor limiting the accuracy of tracked US to CT registration (1-3mm) has been the difficulty in determining the exact location of the bone surfaces in the US images (the response could range from 2- 4mm). Thus it is crucial to localize the bone surface accurately from these images. Moreover conventional US imaging systems are known to have certain inherent inaccuracies, mainly due to the fact that the imaging model is assumed planar. This creates the need to develop a bone segmentation framework that can couple information from various post-processed spatially separated US images (of the bone) to enhance the localization of the bone surface. In this paper we discuss the various reasons that cause inherent uncertainties in the bone surface localization (in B- mode US images) and suggest methods to account for these. We also develop a method for automatic bone surface detection. To do so, we account objectively for the high-level understanding of the various bone surface features visible in typical US images. A combination of these features would finally decide the surface position. We use a Bayesian probabilistic framework, which strikes a fair balance between high level understanding from features in an image and the low level number crunching of standard image processing techniques. It also provides us with a mathematical approach that facilitates combining multiple images to augment the bone surface estimate. Keywords: Ultrasound, Bone, Segmentation, Automatic, Image Registration, CT 131