Medical Imaging: Illuminating the body

Hi,

My name is Franz Devantier, creator of this blog.  I am an Herbalist, who uses local and indigenous herbs when available, in preference to imported herbs.  Because Herbalists deal with living human beings, it is important to have an understanding of Anatomy and Physiology, as well as many other related subjects, such as How to grow old gracefully with Stem Cell Enhancers.

Medical Imaging: Illuminating the body

Before the 1950s, the X-Ray was the only way of extracting information about the internal state of the human body.  Unfortunately the images were a bit murky, but fairly useful.  For the rest of it, physicians had to examine the internal organs for evidence of disease by means of exploratory surgery.  Exploratory surgery subjected the patients to all the pain, shock and trauma of major surgery, but potentially without the benefit of any improvement to their condition.

An X-ray image is obtained by directing, X-rays, which are waves of a very short electromagnetic wavelength at the body.  The X-ray or radiograph is a shadowy negative of the internal structures of the body.  The denser structures absorb more X-rays, and so appear as lighter areas in the radiograph.  Hollow air containing structures and fat, absorb the X-rays to a lesser extent, and so appear as darker areas in the radiograph.  X-ray images can be viewed on a fluorescent screen or fluoroscope as they are being generated. 

X-rays are best at helping to visualize hard bony structures, and at locating abnormally dense structures, such as tumors and tuberculosis nodules in the lungs.

In the 1950s the use of nuclear medicine started.  Nuclear medicine uses radioisotopes to scan the body.  Also in this same period, we saw the advent of ultrasound techniques for scanning the human body.

 In the 1970s CT, PET, and MRI scanning techniques were introduced.  These new imaging techniques were able to reveal the structure of our insides.  Also using these techniques it was possible for the first time to get information about how the molecules were working inside our organs.

The best known of these three new techniques is the Computed Tomography (CT), which was originally known as Computerized Axial Tomography (CAT).  The CT is a refined version of the old X-ray equipment.  The patient is slowly moved through the doughnut shaped CT machine, while its X-ray tubes rotate around the body, and send beams from all directions to a specific level of the patient’s body.

At any point in time, the an-shaped beam of the CT machine is confined to  a slice of the human body, about as thick as a coin.  In conventional X-rays, there can be confusion because of overlapping structures.  In CT, the devices computer translates this information into a detailed cross sectional picture of each of the consecutive body regions scanned.  In other words the result could look similar to thin slices cut through the body for examination.

The CT scan has eliminated the need for exploratory surgery to a very large degree.  CT scans are the chosen method for evaluating most problems involving the brain.  CT is also fairly useful in examining the abdomen and certain skeletal problems.

Dynamic Spatial Reconstruction (DSR), is a special high speed CT device.  This technique provides   three dimensional images of the body organs, from any angle.  This technique also allows the movements and changes in the internal volumes of the organs to be scrutinized at normal body speed.  You can also see the internal body movements in slow motion, or examine them at a specific point in time.  DSR can be used to evaluate the lungs and other mobile organs.  The greatest value of DSR has been to visualize the heart beating, and blood flowing through the blood vessels; which allows heart defects, constricted blood vessels, and the status of a coronary heart bypass graft to be evaluated.

There is another computer assisted X-ray technique that is called Digital Subtraction Angiography (DSA).  Angiography refers to vessel pictures.  This technique will provide an unobstructed view of diseased blood vessels.  The principle is straight forward:  Conventional radiographs (X-rays) are taken before and after a contrast medium has been injected into an artery.  The computer subtracts the before image from the after image, which eliminates all the body structures that obscure the vessel.  The result is an unobstructed view of a diseased blood vessel.  DSA is very useful in identifying blockages of the arteries that supply the heart wall and the brain. 

So we can see that there have been a number very useful technologies based on X-rays.  In the same way nuclear medicine gave rise to a technology called Positron Emission Tomography (PET).

PET is a nuclear medical imaging technique that produces a three-dimensional image or picture of functional processes in the body.  The technology works by detecting pairs of gamma rays, that are emitted indirectly from a positron emitting radionuclide or tracer.  This tracer is introduced into the body on a chosen biologically active molecule.  Three dimensional images of the tracer concentration is created by computer programs.  In some machines a CT scan is run at the same time from the same machine.

One biologically active molecule that is chosen is an analogue of glucose.  The aim with this tracer is to indicate the tissue metabolic activity, based on the concentration of the regional glucose uptake.  This technology can be used to detect cancer metastasis, which is when cancer starts spreading to other areas in the body.  Besides glucose, there are other radiotracers that can be used to study many types of molecules and imaging of tissue concentrations.

The gamma ray is indicated by that funny looking “y” symbol.  This technology can produce vivid coloured pictures of the brains chemical activities.  PET has been very useful in studying brain activity in Alzheimer’s disease, and Epilepsy.  Visualizations of which part of the brain is active during talking, listening, problem solving etc, and be created with PET.  Before PET this would not have been possible.

My favourite imaging technology is Sonography or Ultrasound Imaging.  Firstly Sonography equipment is inexpensive, when compared to the other technologies.  Secondly it is much safer when compared to X-ray or nuclear technology.  The high-frequency or ultrasound waves that are used, seem to be safer than the ionizing forms of radiation used in nuclear medicine, or the X-rays used in CT technology.

In Sonography, the body is probed with pulses of sound waves that are reflected and scattered by body tissues and result in echoes being formed.  A computer analyses these body echoes and creates or constructs visual images of the outlines of body organs.  Often a single hand held device can be used to emit the sounds and to pick up the echoes.  This device can be moved around the body, allowing sections to be scanned from many different body planes.

Sonography is relatively safe, and because of this it is the technique that is chosen for obstetrics.  It can be safely used to determine the fetal position and the age of the fetas, and other information about the fetas.  It is also used to locate the placenta.

On the negative side, sound waves have a very low penetrating power, and rapidly dissipate in air.  Because of this Sonography is of little use in studying the structures of the lungs, or those structures that are surrounded by bone, such as the brain and the spinal cord.   

Franz Devantier,

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Body Cavities and Membranes

Hi,

My name is Franz Devantier, creator of this blog.  I am an Herbalist, who uses local and indigenous herbs when available, in preference to imported herbs.  Because Herbalists deal with living human beings, it is important to have an understanding of Anatomy and Physiology, as well as many other related subjects, such as How to grow old gracefully with Stem Cell Enhancers.

Body Cavities and Membranes

Within the axial portion of the body there are two large cavities.  They are called the dorsal body cavity and the ventral body cavity.  Both of these cavities are closed to the outside, and each of them contains internal organs. 

Dorsal Body Cavity

The dorsal body cavity is sub-divided into two cavities.  The cranial cavity, the skull encases the brain.  The vertebral or spinal cavity, the bony vertebral column encases the delicate spinal cord.  The spinal cord issues from, and is essentially a continuation of the brain.  The cranial and spinal cavities are continuous with one another.  This gives some meaning to the way some people are humorously  described as; “sitting on their brain”, because if you are sitting half on your back, you are sitting on the continuation of your brain, your spinal cord.

The vital and very fragile nervous system organs are both housed by the dorsal body cavity.  The dorsal body cavity is well protected by the skull, and the bony vertebral column.  They are known as the dorsal body cavity, because the spinal cord is on the dorsal side of the body.  The brain is located more to the dorsal side of the skull, then the ventral side, to make space for the structures of the face.

Ventral Body Cavity

The ventral body cavity is larger than the dorsal body cavity, and is located more anterior in the body.  Consider that the ventral body cavity is located anterior to the dorsal body cavity.  The ventral body cavity has two major sub-divisions; the thoracic cavity, and the abdominopelvic cavity.  The ventral body cavity houses a group of internal organs that are collectively called the viscera, or visceral organs.

The superior sub-division is called the thoracic cavity.  The thoracic cavity is surrounded by the ribs and the muscles of the chest.  The thoracic cavity is further subdivided into two lateral pleural cavities.  Each pleural cavity houses a lung. The medial mediastinum, which is located between the two pleural cavities houses the pericardial cavity.  The pericardial cavity encloses the heart, and the remaining thoracic organs or viscera such as the esophagus and trachea.

The thoracic cavity is separated from the inferior abdominopelvic cavity by the diaphragm.  The diaphragm is a dome shaped muscle that is important in breathing.  The abdominopelvic cavity has two parts or regions, which are not separated by a muscular or membrane wall.

The superior portion of the abdominopelvic cavity is the abdominal cavity.  The abdominal cavity contains the stomach, intestines, spleen, liver, kidneys, pancreas and etc.  The inferior part or region the pelvic cavity contains the bladder, some of the reproductive organs, and the rectum.  The abdominal and pelvic cavities are not aligned with each other, because the bowl shaped pelvic region is tipped forward, away from the perpendicular. 

In a physical trauma such as a motor car accident, the most venerable abdominopelvic organs are those in the abdominal cavity.  This is because the organs in this region are only protected by the walls of the trunk muscles, and are not re-enforced by bone, as is the thoracic cavity.  Also the pelvic organs have better protection because the bony pelvis provides a degree of protection.    

Franz Devantier,

How to grow old gracefully with Stem Cell Enhancers.

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Orientation and Directional Terms

Hi,

My name is Franz Devantier, creator of this blog.  I am an Herbalist, who uses local and indigenous herbs when available, in preference to imported herbs.  Because Herbalists deal with living human beings, it is important to have an understanding of Anatomy and Physiology, as well as many other related subjects, such as How to grow old gracefully with Stem Cell Enhancers.

Orientation and Directional Terms

Term	Definition	Example
Superior (Cranial)	Toward the head end or upper part of a structure or body; above.	The forehead is superior to the nose.
Inferior (Caudal)	Away from the head end or toward the lower part of a structure or the body; below.	The navel is inferior to the breastbone.
Anterior (Ventral)	Toward or at the front of the body; in front of.  (In humans anterior and Ventral are synonymous, in four legged animals and fish, Ventral refers to the belly of a vertebrate animal and is the Inferior surface. )	The breastbone is Anterior to the spine.
Posterior (dorsal)	Toward or at the back of the body; Behind.  (Posterior and dorsal surfaces are the same in humans, the term ‘dorsal’ specifically refers to an animals back.  The dorsal surface of a four legged animal or fish is their superior surface.)	The heart is posterior to the breastbone.  The dorsal fin of a fish, is the fin on its back.
Medial	Toward or at the midline of the body; on the inner side of.	The groin is medial to the thigh.
Lateral	Away from the midline of the body; on the outer side of.	The eye is lateral to the bridge of the nose.
Intermediate	Between a more medial and a more lateral structure.	The collarbone is intermediate between the breastbone and shoulder.
Proximal	Closer to the origin of the body part or the point of attachment of a limb to the body trunk.	The elbow is proximal to the wrist.
Distal	Farther from the origin of a body part or the point of attachment of a limb to the body trunk.	The knee is distal to the thigh.
Superficial	Toward or at the body surface.	The skin is superficial to the skeleton
Deep	Away from the body surface; more internal.	The pelvis is deep to the buttock muscles.

Franz Devantier,

How to grow old gracefully with Stem Cell Enhancers.

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Body Planes and Sections

Hi,

My name is Franz Devantier, creator of this blog.  I am an Herbalist, who uses local and indigenous herbs when available, in preference to imported herbs.  Because Herbalists deal with living human beings, it is important to have an understanding of Anatomy and Physiology, as well as many other related subjects, such as How to grow old gracefully with Stem Cell Enhancers.

Body Planes and Sections

In the study of Anatomy, the body is often sectioned or cut along a flat surface called a plane.  The most frequently used planes are sagittal, frontal, and transverse planes.  A section bears the name of the plane along which it is cut.  So a cut along a sagittal plane produces a sagittal section.

Sagittal plane:

The sagittal plane lies vertically and divides the body into the left hand part and the right hand part.  The sagittal plane that is exactly in the middle of the body is called the  midsagittal plane or the median plane.  All the other sagittal planes that are offset from the center, either to the left or to the right are called parasaggital planes.  Para means near, so parasagital means near to the midsagittal plane.

Frontal Plane:

Frontal planes are also vertical planes, however the frontal plane divides the body into the anterior part and the posterior part.  The anterior is the front and the posterior is the back, so the frontal plane divides the body into the front and back parts.  A frontal plane is also called a Coronal plane.  There are many frontal planes, all just a little more posterior or anterior than the previous one.

Transverse or Horizontal plane:

A transverse plane is in the same plane as the floor that the subject is standing on.  It divides the body into the superior and inferior parts.  Superior means above, and inferior means below.  There are many possible transverse planes all the way from the head and down to the feet.  A transverse section can also be called a cross section.

Cuts made along any plane that lie diagonally between the horizontal and vertical are called oblique sections.  Oblique sections can be confusing and difficult to interpret, and so they are not used much.

The ability to interpret sections through the body, especially transverse sections, are very important in the clinical sciences.  Medical imaging devices produce sectional images, rather than three dimensional images.  It can be difficult to decipher an object’s overall shape from sectioned material.  A cross section of a banana for example, looks like a circle, and gives no indication of the whole bananas crescent shape.  In the same way, sectioning the body or an organ along different planes, could result in very different views.

If you took a transverse section of the body trunk at the level of the kidneys, then you would see the kidney structure in the cross section very clearly.  A frontal section of the body trunk would show a different view of the kidneys.  A midsagittal section would miss the kidneys altogether.  The art is in relating two dimensional cross sections to three dimensional shapes.

Franz Devantier,

How to grow old gracefully with Stem Cell Enhancers.

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The Language of Anatomy

Hi,

My name is Franz Devantier, creator of this blog.  I am an Herbalist, who uses local and indigenous herbs when available, in preference to imported herbs.  Because Herbalists deal with living human beings, it is important to have an understanding of Anatomy and Physiology, as well as many other related subjects, such as How to grow old gracefully with Stem Cell Enhancers.

The Language of Anatomy

Most of us are curious about our bodies, we all have one, and we deserve to understand how it works.  However when you hear Anatomical terminology, it discourages most of us from going any further.  Actually the terminology is designed to simplify things.  For example, if you are looking at a book, “above” will always mean in that area on top of the book.  The Human Body has many protrusions, bends and unique shapes.  If we were to say “above” while referring to the Human Body, then the question is, above what?  Above the head, or above the shoulders, or above the legs, or above the knees. 

Anatomists have a universally accepted terminology that allows body structures to be located and identified precisely, with a minimum of words.  This makes a reference to the Human Body very precise and efficient.  It is not part of our everyday language, and so we have to learn it.

Anatomical Positions and Directional Terms

To describe body parts and position accurately, we need to start off with a point of reference.  From this point of reference we can then use directions etc.

The point of reference that I refer to here is the “Anatomical Position”.  Before I can explain further it is very important that you understand the Anatomical position properly.  In the anatomical position, the body is standing up straight.  The feet are together.  The arms are hanging down at the sides.  The palms of the hands are facing forward, and the thumbs are pointing away from the body.  The hands are the only part of the body that have been adjusted in the anatomical position.  They have been turned so that the palms face roward.

The Anatomical position is therefore like: A person standing to attention with the palms of the hands facing forward, and the thumbs facing away from the body.  Strictly speaking the person would also be standing with the weight on the balls of the feet, and heels of the feet lifted slightly.

This is our reference point, the anatomical position.  Before you continue, stand up for a moment in the anatomical position, to make sure that you properly understand it.

Now all of the references to the body from an Anatomists perspective are described as if the body was in the Anatomical position.  Regardless of the actual position that the person may be in. 

Now another important point, when you are standing in front of a person or a cadaver, the person’s right side is on your left side and vice versa.  When you speak of the left or right side of the body, it is always from the reference point of the subject you are looking at.  So you will need to adjust this in your mind, depending on whether the subject is facing you, or facing away from you.

Directional terms used by Anatomists, describe a body structure in relation to another body structure.  In normal language we could for example say. “The ears are located on each side of the head, to the right and left of the nose”.  An Anatomist would only need to say, “The ears are lateral to the nose”.  Although you may use some of the Anatomical terms in everyday conversation, when these terms are used in the context of anatomy, they take on a very precise meaning.

Regional Terms

The first fundamental division of the body is into the Axial and the Appendicular parts.  The axial part is the core of the body and consists of the Head, Neck and Trunk.  The Appendicular part consists of the appendages or limbs, which are attached to the body’s Axis.

The regional terms that are used, are universal names that point to very specific areas of the body.  Most of these anatomical areas also have a common name, that refers to more or less the same area.  So what- ever language you speak or learn, the Anatomical terms are going to remain the same. “Cervical”  will mean the neck regardless of your specific language.

To start with the body has an Anterior side which is the front side of the body, and a Posterior side, which is the back of the body.  If we are looking at the body from the Anterior side or the front then these are the basic structures that we will see, starting at the top and working down.

-> Frontal (known as the forehead in layman’s terms)

-> Orbital  (eye)

-> Nasal (nose)

-> Buccal (cheek)

-> Oral (mouth)

-> Mental (chin)

-> Cervical (neck)

-> Acromial (point of the shoulder)

-> Sternal (breastbone)

-> Axillary (armpit)

-> Thoracic (chest)

-> Mammary (breast)

-> Brachial (arm or upper arm)

-> Antecubital  (front of elbow)

-> Abdominal (abdomen)

-> Umbilical (navel)

-> Antebrachial (forearm)

-> Pelvic (pelvis)

-> Inguinal (groin)

-> Pubic (genital region)

-> Coxal (hip)

-> Carpal (wrist)

-> Palmar (palm)

-> Pollex (thumb)

-> Digital (fingers)

-> Femoral (thigh)

-> Patellar (anterior knee)

-> Crural (lower leg)

-> peroneal (outside part of lower leg)

-> Tarsal (ankle)

-> Digital (toes)

-> Hallux (Great toe)

-> Pedal (refers to the whole foot)

Now let’s imagine that the subject is standing with their back to us, or more correctly we are looking at them from the posterior side.  The person is standing in the anatomical position.  We would see from the top of the body and down towards the feet.

-> Otic (ear)

-> Occipital (back of head or base of skull)

-> Cephalic (Head)

-> Acromial (point of shoulder)

-> Vertebral (spinal column)

-> Scapular (shoulder blade)

-> Brachial (arm)

-> Olecranal (back of elbow)

-> Upper Extremity (arm)

-> Manus (hand)

-> Dorsum or Dorsal (back)

-> Lumbar (loin)

-> Sacral (piece of spine between the hips)

-> Gluteal (buttock)

-> Perineal (Area between the anus and the external genitalia)

-> Femoral (thigh)

-> Popliteal (back of the knee)

-> Sural (calf)

-> Calcaneal (heel)

-> Plantar (sole)

-> Lower extremity (leg)

Franz Devantier,

How to grow old gracefully with Stem Cell Enhancers.

Income stabilizer (win-win opportunity)

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