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REGIONAL COOPERATIVE AGREEMENT INTERNATIONAL ATOMIC ENERGY AGENCY Distance Assisted Training Programme for Nuclear Medicine Technologists Edited by: Heather E. Patterson, Brian F. Hutton An introduction to Cross Sectional Anatomy PART 1: PART 2: Authors: Elisabeth Kilburn-Watt Paul Roach, Denis Gradinscak Scott Evans, Robin Cassumbhoy Module Unit The material within this document should be regarded as the property of the International Atomic Energy Agency and should be reproduced or used only in accordance with the attached statement of ownership. (version 4) Statement of ownership (proposed) All materials which form part of the project ‘Distance assisted Training for Nuclear Medicine Technologists’, including any translation of these materials, remain the property of the IAEA, Vienna. In addition the names of the original authors and editors of the material shall be acknowledged at all times. 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Box 100, A‐1400 Vienna, Austria b Introduction to Sectional Anatomy CONTENTS page Flowchart c Outline 1 PART 1 What is Sectional Anatomy 1 The language of sectional anatomy Planes Sections 2 4 5 Sectional anatomy of the chest 8 Sectional anatomy of the abdomen 13 Sectional anatomy of the pelvis 18 Sectional anatomy of the brain Transverse Coronal 20 22 25 PART 2 An Exercise on familiarity with Cross Sectional Anatomy on the internet DAT website on‐line familiarity with CT Cross Sectional Anatomy and integration with SPECT and PET. c 29 Introduction to Sectional Anatomy What is Sectional Anatomy The language of sectional anatomy Planes Sections Sectional anatomy of the chest Exercise Sectional anatomy of the abdomen and pelvis Exercise Sectional anatomy of the brain Transverse Coronal Exercise Exercise www various interactive websites PART 2 OL – DAT web activity d Introduction to Cross Sectional Anatomy Technical Writer: Production Editor: Elisabeth Kilburn-Watt Heather Patterson Outline: Traditionally, the images we have taken in Nuclear Medicine have been 'planar' images. By this, we mean that when we collect and display images of the distribution of a radiopharmaceutical in the body (or organ), it is as though the distribution was in a single plane or on a flat surface. There is no 'depth' to the images. An anterior view obtained with a stationary camera is a 'flat' image of the distribution of activity. It gives us little idea of the location of a hot or cold spot in an organ, such as the liver, in terms of whether it lies anteriorly or posteriorly in the organ. We have been able to obtain further information about the anatomical position of a lesion by taking lateral or oblique views. By looking at an organ in a number of 'flat' images taken from different view points, we are able to get an idea of the location of a structure that is deep within the body. With the development of SPECT camera systems, we have the ability to display radiopharmaceutical distribution to show the structures of the body in cross sectional planes. That is, in planes (or flat surfaces) that could be obtained by cutting/slicing the body and viewing an internal surface. We are looking at our organs from a totally different viewpoint. This means we have to be able to recognise our anatomical structures from this different viewpoint. We need to have some knowledge of Sectional Anatomy. More recently the introduction of SPECT/CT and PET/CT enables further enhancement and localisation of organs, vessels and other structures through image fusion. i.e. the ability to view exact positions of areas with radiopharmaceutical uptake such as functioning organs and active tumours within surrounding structures as imaged with Computerised Tomography. At the conclusion of Part 1 there are directions to several websites on the internet which you are encouraged to explore and further enhance your knowledge and ability to recognise anatomical locations in transverse, sagittal and coronal planes. In Part 2 of this Unit you will be directed to log_on to the DAT website and follow the links to ………… (name). Here you can step through the slices of transverse, coronal and sagittal views in CT, PET and fused images with labelled areas of interest to help orientate their locations. There are self assessment tests to assist with your understanding during your study of this Unit followed by ‘on-line’ multiple choice questions which will record your results as part of your final assessment. 1 Objectives: • • • • On completion of this unit you will be able to look at anatomy in a different way recognise the structures you are already familiar with when they are displayed in different sectional planes. demonstrate interactive control as you move through transverse, coronal and sagittal slices on-line. identify locations of functioning organs, vessels and tumour sites within the body structures As well, this module is meant only as an introduction to sectional anatomy. We will not be going into the depth of detail that would be found in a full sectional anatomy course. This module should be a good introduction to such a course if you want to take one in the future. Time Check: Allow 8 hours to study and complete PART 1 on Cross Sectional Anatomy and a further 6 hours to complete PART 2 on-line. 2 Introduction: What is Sectional Anatomy? Sectional Anatomy is concerned with the position and anatomical relationships of structures of the body in various sectional planes. When we first learn anatomy we tend to learn it as though we are looking at the body from the front or the back - much like what we tend to see on an anterior or a posterior planar image. We learn some superior and inferior relationships - we learn where the kidneys are relative to the ribs and the pelvis - but we don't tend to think where the colon is relative to the left kidney or where the stomach lies relative to the spleen and left kidney. Which one is more anterior? Or lateral? Or superior? However if we are going to be looking at sectional images through the abdomen, we need to know some of these relationships so that we can correctly identify structures on different slices. Sectional anatomy is best learned by looking at Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) images or sectional anatomical specimens because they show so much detail and give so much information about the relationships between organs. The anatomical detail seen on a CT scan is much greater than we can see on SPECT images. However, what we can learn from this material can give us the skills to interpret anatomy on our own images. What this Sectional Anatomy Unit is Not? It is not intended that this unit will teach you anatomy. It is assumed that you have knowledge of traditional anatomy. Note ! Pre-requisite If you find that there are anatomical structures referred to that you are not familiar with, you may need to revise the anatomy of that organ or organ system before continuing with this work/refer to a textbook of anatomy for this information. The Language of Sectional Anatomy Firstly, we need to look at the terminology/language that is used in sectional anatomy. Because sectional anatomy looks at the relationships between organs, the language/terminology used is about the position of structures relative to one another. You will be familiar with most of these terms already. Please refer to Figure 1 to remind yourself about these terms and what they mean. 3 Superior Medial Lateral Proximal end of forelimb Distal end of forelimb Proximal end of thigh Distal end of thigh Proximal end of leg Lateral region of leg Medial region of leg Distal end of feet Inferior Posterior view Anterior view Figure 1. The body in the anatomical position and some directional terms. The body is erect, eyes forward, arms at the sides and palms and toes directed forward. Adapted from: Human Anatomy and Physiology - Solomon & Davis. Publisher New York McGraw-Hill, ©1978. • ISBN: 007059645X The most commonly used terms are as follows: Superior (cranial) towards the head or the upper part of a structure Inferior (caudal) away from the head or towards the lower part of a structure Anterior (ventral) nearer to or at the front of the body Posterior (dorsal) nearer to or at the back of the body Lateral further from the midline of the body or a structure Medial Adjacent Proximal Distal • • nearer to the midline of the body or structure next to or very close to nearer to the point of origin or attachment to the trunk further from the point of origin or attachment to the trunk eg - the heart is superior to the liver eg - the stomach is inferior to the lungs eg - the sternum is anterior to the heart eg - the oesophagus is posterior to the trachea eg - the ascending colon is lateral to the urinary bladder eg - the ulna is medial to the radius eg - the superior vena cava is adjacent to the aorta eg - the humerus is proximal to the radius eg - the carpal bones are distal to the radius Combinations of these words are often used such as: postero-lateral - nearer to the back and further from the midline For example: - the spleen is postero-lateral to the stomach antero-medial - nearer to the front and closer to the midline For example: - the right ventricle is antero-medial to the left ventricle 4 Planes and Sections a) Planes The human body and its anatomy can be discussed with respect to a number of planes. These are imaginary flat surfaces that pass through the body. Please refer to Figure 2 Cranial (superior) Frontal (coronal) plane Mid-sagittal plane Transverse plane Posterior (dorsal) Anterior (ventral) Inferior Adapted from: Human Anatomy and Physiology - Solomon & Davis. Publisher New York McGraw-Hill, ©1978. • ISBN: 007059645X Figure 2. Planes of section. The body or its parts may be cut in sagittal, transverse or coronal sections. The commonly used planes (imaginary surfaces) are shown in the diagram - all the terminology used refers to the body in the upright anatomical position: A sagittal plane is a vertical plane that divides the body (and organs) into right and left sides. A mid-sagittal plane (also called a median plane) is the vertical plane that passes through the midline of the body and divides it into equal right and left sides. A para-sagittal plane does not pass through the midline and so divides the body into right and left sides that are not equal. A frontal plane - also called a coronal plane - is an imaginary flat surface at right angles to a mid-sagittal or para-sagittal plane and divides the body into anterior and posterior portions. A horizontal or transverse plane is one that is horizontal to the ground (and at right angles to both sagittal and frontal planes) and divides the body and organs into superior and inferior portions. 5 b) Sections When we study sectional anatomy, we are looking at the organs in sections - or flat surfaces - made by cutting through the three dimensional body along one of these planes. When we look at SPECT, CT and MRI images, a computer has been used to reconstruct the data and display it as images as if the body has been cut in these sections. Sagittal sections A sagittal section is made by cutting along a sagittal plane. The cut surface can then be viewed. It would be possible to make a number of sagittal sections of the body, all parallel to one another (one of which would be the mid-sagittal section). • • • If you looked at the sections of the body, in order from right to left, you would be able to identify the various organs and tissues in each section and how they relate to one another. Sagittal sections give information about the anterior/posterior and superior/inferior relationship of structures. For example: Starting from the right side, as you look at sagittal sections at the level of the upper abdomen, the liver is the most obvious structure you see. You obtain information about other structures relative to the liver – e.g. the structures which are superior (e.g. diaphragm) and inferior (e.g. right kidney) as well as structures which are anterior and posterior. As you view the sections going towards the left, you would expect to see the liver get smaller and finally disappear as the stomach and then the spleen became visible. Coronal sections Similarly, coronal sections are made by cutting the body in parallel coronal planes. • • • These coronal sections give information about superior/inferior relationships of structures and medial/lateral relationships. To get information about anterior/posterior relationships, you have to view the sequence of slices eg starting from the anterior aspect and moving through to the posterior. Coronal sections of the brain for example are useful for looking at the relationship of the basal ganglia (which are more lateral) to the third ventricle (which is a medial structure). Transverse sections The most commonly used sections are transverse sections – they are also called axial sections or cross sections. These are obtained by cutting the body in parallel transverse planes and are viewed as though we were looking up from the patient's feet. 6 • • Cross sectional slices give information about anterior/posterior relationships and medial/lateral relationships. To get information about superior/inferior structures, you again have to look at a series of slices. For example: Looking at cross sectional slices of the abdomen; moving down from the diaphragm towards the pelvis, you will see structures such as the liver, stomach and spleen, then these will disappear as the kidneys and then pelvic organs appear. Remember Being able to identify anatomy from these different viewpoints takes time and practice. You need to translate your knowledge of anatomy in the “normal” plane (i.e. in text books of anatomy) into the axial plane. You need to understand how the shape and orientation of anatomy is viewed in other planes. For example: Look at the images below. 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Figure 3. Eight cross sectional/slices of a walking stick. 7 Figure 4a. An apple has been scanned. Figure 4b. Note: skin, stem seeds and air in core. [Flaws in the apple are soft spots, not bites] The above images demonstrate • Figure 3. How a walking stick would appear if we were to scan it and then view it in transverse sections. What we have to learn to do is to look at the sections and reconstruct in our minds the three dimensional structure of the curved handle of the stick. Note: This structure is very similar to the aorta – the ascending portion of the aorta as it leaves the left ventricle and then the descending aorta as it passes down through the chest. Depending on the level at which we make a transverse section through the chest, the aorta may appear on our section in a number of ways. • Figures 4a and 4b. This is a scan of a familiar object – an apple – but getting used to thinking of an apple in this way takes some practice. The main purpose of this module is to give you practice at looking at different sections and identifying the structures that you can see. When you have identified the various structures (and using the other diagrams to help you identify the level you are at), follow the structures as you look at a number of slices. Notice how the structures change shape, how they disappear and new structures appear. Notice the relationship of the various structures to another. Diagrams and either CT or MRI scans have been used to help you identify the structures. Use the labelled diagrams to help you identify the structures on the scans. 8 In your workbook there is another set of images. Once you feel confident about identifying the various structures, try labelling these diagrams. There are also some questions about the relationship of various structures and the section that would be used to best display different structures. Sectional Anatomy of the Chest To start looking at the chest in transverse sections, we first need to have a good idea of the structures in the chest and their relation to one another. Look at the following diagrams showing an anterior and a lateral view of the heart. Inferior pharyngeal constrictor muscle Thyroid cartilage Cricoid cartilage Cricopharyngeus muscle 1 Pulmonary valve 1 Aorta Sternum 2 2 A 3 Trachea Esophagus P Heart in pericardium 3 Aortic valve 4 4 Diaphragm 5 T Mitral valve 5 M 6 6 7 Tricuspid valve Anterior view of the heart 7 Left lateral view of the heart Figure 5. Looking at these views together we can get information about anterior/posterior, inferior/superior and medial/lateral relationships within the heart which will help us with identifying structures on transverse sections. For example: THINK! • • • • • • • How does the heart lie in the thorax? Where is it located? Which chamber of the heart is most anterior? Which chamber is most posterior? Are the atria superior and the ventricles inferior as most diagrams show? Which is superior, the aorta or the pulmonary artery? What is the position of the superior vena cava relative to the aorta? If you have a understanding about these relationships it makes looking at transverse sections easier. 9 The following diagram shows the approximate levels at which the transverse sections of the chest were made. Use it to help you identify structures in the next three sections. Diagram showing levels of transverse sections of the chest T1 T2 section 1 section 2 T9 section 3 T 10 T 11 T 12 Figure 6. Diagram showing levels of transverse sections of the chest 10 Right Lung Mediastinal fat Sternum Left Lung Superior vena cava Ascending aorta R. pulmonary a. R. superior pulmonary v. Pulmonary trunk L. superior pulmonary v. R. bronchus intermedius L. upper lobe bronchus Esophagus Descending branch of l. pulmonary a. Azygos v. L. main bronchus Descending aorta Figure 7a. Section 1: Transverse section of chest at the level of T6 Fig 7b. CT scan of chest at the level of T6 Fig 7c. SPECT 67Ga study at level T6 Figure 7a, b & c. • • • • • • The CT transverse section shown in figure 7b is taken approximately at the level of the 6th thoracic vertebra. The section passes through the pulmonary artery at the point where it gives rise to the right pulmonary artery and below the origin of the left pulmonary artery (which is why it appears as a separate circle – think of the walking stick). The section is also below the arch of the aorta – so the ascending and descending arteries appear separately – note their relative positions. Comparing the diagram with the CT scan makes it easy to identify the structures that are filled with air – the lungs and the bronchi. The bony structures are also easy to identify on the CT scan due to the high density of bone – identify the sternum, vertebra, ribs (some of these are cut because they are not horizontal structures). Identify the superior vena cava and the oesophagus. Where is the trachea? ************************************* 11 Fleck of calcium in ascending aorta R. ventricle L. ventricle R. atrium Diaphragm and top of liver L. atrium R. inferior pulmonary v. L. inferior pulmonary v. Descending aorta Esophagus Azygos v. Figure 8a. Section 2: Transverse section of chest at the level of T8 Fig 8b. CT scan of chest at the level of T8 Fig 8c. SPECT 67Ga study of level T8 • • • • • Figures 8a, b & c The transverse section shown in figure 8b is taken approximately at the level of T8. Note the relationship of the right and left ventricles – remember the orientation is as though the patient is lying supine and we are looking up from his feet towards his head. Note the positions of the right and left atria. Note that we are now below the level of the pulmonary arteries (but we can see the pulmonary veins) and we no longer see the superior vena cava. We can still see the ascending aorta. The dome of the right lobe of the liver is now visible. ****************************************** 12 R. lung in anterior costodiaphragmatic recess R. ventricle Interventricular septum R. atrium L. ventricle Pericardium Liver L. atrium Esophagus Descending aorta Azygos v. Figure 9a. Hemiazygos v. Section 3: Transverse section of chest at the level of T9 / T10 Fig 9a. CT scan of chest at the level of T9/T10 • • • • • Fig 9b. SPECT 67Ga study at the level of T9/T10 Figures 9a, b & c The next section is taken a little below at approximately T9 / T10. Note the relative positions of the ventricles and the interventricular septum. Note the pericardium. The ascending aorta is no longer visible. Note how far posterior the descending aorta lies. The right lobe of the liver is more obvious. Go to your Workbook Sectional Anatomy and complete question 1 13 Sectional Anatomy of the Abdomen and Pelvis To be able to appreciate transverse sections of the abdomen, we again need to look at an anterior view (coronal section) to remind ourselves of the relationship of the various organs. Look at figure 10 to remind you of what you would expect to find at different levels. Because it is a diagram with some organs removed it also gives you some idea of the anterior/posterior relationships. Use it to get some idea of the relative position of the structures before moving on to the transverse sections. Where is the pancreas relative to the spleen? Where is the abdominal aorta relative to the superior vena cava? What is the relationship of the gall bladder relative to the pelvis of the right kidney? Which is superior, the portal vein, the hepatic veins or the hepatic artery? Ask yourself these types of questions – it will help you develop a three dimensional view of the abdomen. Inferior vena cava Aorta Hepatic veins Left gastric a. Splenic a. Liver Spleen Inferior vena cava Tail of pancreas Gall bladder Celiac trunk Common bile duct Common hepatic a. Duodenum Major duodenal papilla (ampulla of Vater) Superior mesenteric a. Superior mesenteric v. Pancreatic duct Inferior vena cava Head of pancreas Aorta Figure 10. Diagram of the abdomen 14 Diagram showing levels of transverse sections of the abdomen section 1 T-12 section 2 L-1 L-2 section 3 L-3 L-4 L-5 Figure 11. This diagram shows you the approximate levels at which the transverse sections of the abdomen were taken. It should help you to identify the various structures you see. 15 Muscular insertions of diaphragm Groove for ligamentum teres Stomach Gastroesophageal junction middle and r. hepatic vs Descending aorta Inferior vena cava Spleen R. lobe of liver L. Lung in posterior costodiaphragmatic recess Azygos and hemiazygos R. lung in posterior costodiaphragmatic Figure 12a. Section 1: Transverse section of abdomen at the level of T11 Fig 12b. CT scan of abdomen at the level of T11 • • • • Fig 12c. SPECT 99mTc-MIBI study at the level of T11 Figures 12a, b & c. This transverse section is taken at approximately the level of the 11th thoracic vertebra. The most obvious structure is the liver – note the right and left lobes – note the relative position of the spleen and the left lobe of the liver. Identify the inferior vena cava and the hepatic veins draining into it. Note that the posterior inferior portions of the lung are still visible. Identify the stomach and the inferior portion of the oesophagus. Note again the position of the aorta. *********************************************** 16 Lateral segment, l. lobe of liver Medial segment, l. lobe of liver Splenic flexure of colon Interlobar fissure Stomach Common hepatic a. Celiac trunk Portal v. Tail of pancreas Inferior vena cava L. adrenal R. adrenal Aorta Calcium in aorta L. kidney Osteophyte Figure 13a. L. crus of diaphragm Section 2: Transverse section of abdomen at the level of L1 Figure 13b. CT scan of abdomen at the level of L1 Figure 13c. SPECT 99mTc-MIBI study at the level of L1 Figures 13a & b This transverse section is taken a little below figure 12, at about the level of the 1st lumbar vertebra. • • • • • • The liver is still the most prominent structure on the right side – identify the portal vein and the hepatic artery. Note that the stomach is now seen as a smaller structure - this would be the inferior portion of the body of the stomach. Identify the splenic flexure of the colon and the tail of the pancreas – why is only the tail seen here? Note that the left kidney is now seen – why not the right kidney? Note that both adrenal glands are seen – they appear like “flying birds” on the CT scan. Identify the inferior vena cava and note its position relative to the aorta. **************************************************** 17 Pyloric antrum of stomach Gallbladder Distal transvers colon R. lobe of liver Body of pancreas Duodenum Superior mesenteric v. Usual site of common bile duct in head of pancreas Superior mesenteric a. Small bowel loops Inferior vena cava Descending colon Aorta L. renal a. L. kidney R. kidney Figure 14a. Section 3: Transverse section of abdomen at the level of L2 Figure 14b. CT scan of abdomen at the level of L2 Figures 14a, b &c. • • • • • • • • Figure 14c. SPECT 99mTc-MIBI study at the level of L2 This section is a little lower again – about the level of L2. The liver appears smaller here – only the right lobe of the liver would extend down to this level. Identify the gall bladder – note how anterior it is in this patient. Identify the stomach – it seems larger again – this is because this slice/section is taken through the pylorus of the stomach which is like a tube. Note how far to the right side the pylorus of the stomach extends – it is then continuous with the beginning of the duodenum which then disappears as it continues inferiorly. Identify the head and body of the pancreas – the tail was visible in the slice above because it is superior to the body. Note the location of portions of small and large bowel. Identify the left kidney and the left renal artery arising from the aorta – the upper pole of the right kidney is now visible. Note the relative positions of the inferior vena cava and the aorta. 18 The next two sections are taken through the pelvis. The main interest we have in the pelvis is the bony structures which are shown very well on the CT scans. However it is interesting to note the position of the ureters and the iliac vessels as well as the relationship of the urinary bladder and the prostate gland. Small bowel Fat around tendon in psoas m. Anterior superior illiac spine Lumbosacral trunk Iliacus m. Iliac wing L. ureter L. common iliac a. Gluteus minimus m. Gluteus medius m. L. internal iliac v. L. external iliac v. Sacroiliac joint Gluteus maximus m. Neural foramina in sacrum Figure 15a. Transverse section of the pelvis at the level of S1 Figure 15b. CT scan of abdomen at the level of S1 • • • • • • Figure 15c. SPECT 99mTc-MIBI study at the level of S1 Figures 15a, b & c. This is a transverse section of the pelvis at the level of 1st sacral vertebra. Identify the sacrum and the sacroiliac joints. Note the positions of the iliac arteries and their position relative to the iliac veins. Identify the ureters. Identify loops of small bowel Note the large muscle masses associated with the pelvis. Unlike the sections in the abdomen, this slice appears symmetrical, there are no obvious right or left sided structures. Important to Remember It is important to remember our orientation - we are looking from the patient’s feet toward his head - so his right is on our left (as for an anterior view). 19 Femoral a. and v. Symphysis pubis Sartorius m. Iliopsoas Rectus femoris m. Pectineus m. Tensor fasciae latae m. Oburator canal Prostate and bladder neck Acetabulum Head of femur Ischium Gluteus maximus m. Transverse perineal m. Rectum Coccyx Levator ani m. Figure 16a. Transverse section of the pelvis at the level of the coccyx Fig 16b. CT scan of the pelvis at the level of coccyx Fig 16c. SPECT 99mTc-MIBI study at the level of coccyx Figures 16a, b & c. This transverse section is at the level of the coccyx. • • • • • Identify the pubic bones and the symphysis pubis. Identify the head of the femur and the acetabulum. Note the position of the prostrate gland and the neck of the urinary bladder (the body of the bladder was on slices between figure 15 and 16). Note the position of the rectum relative to the bladder neck. Again note the large muscle masses in the pelvic area. Go to your Workbook Sectional Anatomy and complete question 2 20 Sectional Anatomy of the Brain The brain is a very complex anatomical structure. The best view to start with to identify the various structures is a mid-sagittal section. Mid-sagittal Section of the Brain POSTERIOR Choroid plexus of third ventricle Superior cerebral vein Parietal lobe Intermediate mass of thalamus Corpus callosum Arachnoid villus Subarachnoid space surrounding brain Superior sagittal sinus Cerebrum Frontal lobe Lateral ventricle Interventricular foramen Occipital lobe Pineal gland Great cerebral vein Third ventricle Straight sinus midbrain* Pituitary gland Pons Cererbellum Cerebral aqueduct Choroid plexus of fourth ventricle lateral aperature Fourth ventricle Medulla oblongata Median aperature Spinal cord Central canal Note: * midbrain includes corpora quadrigemina (posterior portion of mid-brain) and cerebral peduncles (anterior section of mid-brain line in front of the cerebral aqueduct) Figure 17. Diagram of mid-sagittal section of the brain Figure 18. MRI scan - Mid-sagittal section of the brain 21 • • • • • • • • • • • • To obtain a mid-sagittal section of the brain a cut is made between the two cerebral hemispheres. This cut divides the midline structures that connect the two hemispheres as well as other midline structures such as the cerebellum and brain stem. When we look at the section, the hemispheres are intact and we can identify the gyri and sulci of the hemispheres and the frontal, parietal and occipital lobes. The temporal lobe is just visible anterior to the pons but it is a lateral structure – it does not lie in this plane. The cut surface of the corpus callosum is very prominent (note its appearance on the MRI scan) – this large structure consists of commissural fibres (white matter) carrying information between the hemispheres. The third ventricle is a midline structure – choroid plexus in the third ventricle is visible. On either side of the third ventricle lies the thalamus. Identify the pineal gland. The hypothalamus lies below the thalamus and from this the infundibulum leads to the pituitary gland. In this region the optic chiasm is also found. Identify the cerebral aqueduct leading to the fourth ventricle – there is choroid plexus visible in the fourth ventricle as well. Identify the midbrain structures – the cerebral peduncles and corpora quadrigemina. Note that the pons and the majority of the medulla oblongata lie anterior to the cerebral aqueduct. Identify the cerebellum – note its position relative to the cerebral aqueduct and the occipital lobe. What separates these two structures? Although we have been able to identify many of the structures of the brain on this section, there are structures that lie lateral to this plane that are not seen. One way to display these structures would be to look at other sagittal sections. For example: The lateral ventricles and the basal ganglia are not seen on a mid-sagittal section but would be seen on para-sagittal sections. Other sections such as transverse and coronal sections can also be used to display these structures. However, as we will see, these sections will not display the full extent of a lateral ventricle as well as para-sagittal sections. As we look at these other sections we need to keep referring to the mid-sagittal section to help up with the anterior/posterior and superior/inferior relationships of the structures. 22 Transverse Sections of the Brain The next three sections are transverse sections taken through the brain at the level indicated in the small diagram. Interhemispheric fissure Fat in scalp Fat in diploic space Cerebral grey matter Cerebral white matter Anterior portion of body of corpus callosum Body of lateral ventricle Posterior portion of body of corpus collosum Interhemispheric fissure Superior sagittal sinus Figure 19a. • • • • • MRI scan - Transverse section of the brain This section displays the inter-hemispheric fissure – identify the superior sagittal sinus at the posterior end. The grey matter (cell bodies) of the hemispheres is clearly visible – identify a frontal gyrus and sulcus. Identify the frontal, parietal and occipital lobes. Identify cerebral white matter (nerve fibres) – some of the nerve tracts are association fibres connecting nerve cells in the same hemisphere – some are commissural fibres (eg the corpus callosum) connecting nerve cells in the opposite hemisphere. This section cuts through the superior portion of the body of the lateral ventricles – the true size of the ventricles cannot be appreciated in this section. Figure 19b. Transverse slice of normal HMPAO Brain SPECT study 23 Interhemispheric fissure Genu of corpus callosum Frontal horn of lateral ventricle Septum pellucidum Internal capsule Insula in sylvian fissure Thalamus Head of caudate nucleus Foramen of Munro Putamen Globus pallidus Pulvinar of thalamus Tail of caudate nucleus position of Pineal gland Trigone of lateral ventricle Superior sagittal sinus Figure 20a. • • • • • • • • • • MRI scan -Transverse section of the brain This section is inferior to the one above and cuts through the frontal and posterior horns of the lateral ventricles – again the true size of these structures cannot be appreciated on this section. Identify the septum pellucidum – the structure that separates the two frontal horns of the lateral ventricles. Note the foramen of Munro/interventricular foramen which are the openings which connect the lateral ventricles to the third ventricle and through which Cerebral Spinal Fluid (CSF) passes. Note that only the most superior portion of the third ventricle is seen here – as it is an inferior structure it will be seen on the next section. Identify the genu of the corpus callosum. Note the spaces filled with CSF appear dark on the MRI image – identify the subarachnoid space and superior cistern as well as the ventricles. Identify the thalamus which lies either side of the third ventricle. Note that the pineal gland which is at the posterior portion of the thalamus should appear to be “floating in CSF” in this particular section. Identify the nuclei – masses of grey matter – which are part of the basal ganglia – the caudate nucleus, putamen and globus pallidus. Again identify which lobes of the hemispheres are visible. Note the Insula lobe. Figure 20b. Transverse slice of normal HMPAO Brain SPECT study 24 Eyeball Orbital fat Optic nerve Temporal lobe Upper pons Cerebral vermis Cerebellar hemisphere Superior cerebral peduncle Fourth ventricle Transverse (lateral) venous sinus Figure 21a. • • • • • • MRI scan - Transverse section of the brain This section is made at the base of the brain. Note that the section is below the frontal lobe and only the temporal lobes are still seen. The vermis and hemispheres of the cerebellum occupy the posterior fossa. Identify the fourth ventricle. Identify the pons. Note the cisterns and subarachnoid space filled with CSF. Identify the optic nerves – in a superior section the optic chiasm would have been visible. Figure 21b. Transverse slice of normal HMPAO Brain SPECT study 25 Coronal Sections of the Brain Refer to figure 22 which is a diagram of a coronal section of the brain to assist you with localising structures on the coronal MRI scans. The diagram is at approximately the same level as the second MRI scan. Cerebrum Corpus callosum Lateral ventricle Thalamus Caudate nucleus Corpus stratium Putamen Lentiform Globus nucleus pallidus Third ventricle Insula Hypothalamus Claustrum Internal capsule Optic tract Adapted from: Figure. 22 Infundibulum Pituitary gland Principles of Anatomy and Physiology Tortora and Anagnostakos Publisher John Wiley 1999 ISBN: 0471378011 Diagram of coronal section of the brain Note ! Note that a coronal section gives a better appreciation of superior/inferior relations – the third ventricle can be seen below the lateral ventricles, the lateral sulcus can be clearly seen dividing the parietal lobe from the temporal lobe. The position of the thalamus on either side of the third ventricle is seen as well as the hypothalamus which is inferior to the thalamus. The next three figures are coronal sections taken at the level indicated in the small diagrams. 26 Superior sagittal sinus Frontal gyrus Interhemisphere fissure White matter of Frontal lobe Corpus Callosum Frontal horn of lateral ventricle Cingulate sulcus Caudate nucleus Insula Sylvian fissure Branches of the middle cerebral artery Temporal lobe Figure 23a. • • • • • • • MRI scan - Coronal section of the brain Note the grey matter and white matter – identify gyri, sulci and cerebral white matter. Note the interhemispheric fissure – what structures lie within this fissure? Identify all the lobes of the cerebrum visible on this section. Locate the corpus callosum. Identify the lateral ventricles – which part of these structures is visible here? Identify the lateral/sylvian fissure – what structure lies within this fissure? Branches of what major artery are found in the lateral fissure? Figure 23b. Coronal slice of normal HMPAO Brain SPECT study 27 Parietal lobe Interhemispheric fissure Body of lateral ventricle Caudate nucleus Thalamus Sylvian fissure Third ventricle Temporal lobe Cerebral Peduncle Pons Figure 24a. • • • • • • • MRI scan - Coronal section of the brain Identify structures noted on the previous slice – have any structures/areas disappeared? Identify the lobes of the cerebrum visible on this section. What portion(s) of the lateral ventricles are now visible? Identify the third ventricle – what structure lies on either side of the third ventricle? Note the caudate nucleus (part of the basal ganglia). Identify the hippocampus in the temporal lobe Identify the pons. Figure 24b. Coronal slice of normal HMPAO Brain SPECT study 28 Superior sagittal sinus Parietal lobe Falx cerebri in interhemispheric fissure Straight sinus Supracerebellar cistern Occipital horn of lateral ventricle Tentorium cerebelli Cerebellum Occipital lobe Figure 25a. • • • • • • • Identify structures noted on the previous slice – have any structures/areas disappeared? Identify the cerebral lobes present in the section Identify the falx cerebri in the interhemispheric fissure – what structures lie at the superior and inferior parts of this structure. Identify the tentorium cerebelli. What part of the lateral ventricles are visible (or are supposed to be visible – they are a little difficult to see)? Identify the cerebellum. Identify the CSF filled cistern above the cerebellum Figure 25b. Note: MRI scan - Coronal section of the brain Coronal slice of normal HMPAO Brain SPECT study All the 99mTc- HMPAO Brain SPECT images displayed are an average of normal brain SPECT studies performed on 22 females. The slices displayed are as close as possible to the MRI scan sections displayed. 29 Go to your Workbook Sectional Anatomy and complete question 3 Summary The aim of Part 1 of the Unit has been to start you thinking about anatomy in a different way – you should now be thinking in terms of how organs relate to one another in three dimensional space. This has only been an introduction to the subject - hopefully enough so that you will start looking at CT or MRI scans as well as your SPECT images with greater understanding. Good Idea! The more you practice looking at images in this way the easier it will be become. Nuclear Medicine imaging in the future will probably involve more sectional imaging using radiopharmaceuticals that localise in a number of tissues. Sectional anatomy and the type of thinking it involves will become more important if we are to use our technology to the maximum benefit of the patient. We will probably also need to become more involved with correlating our SPECT and PET images with CT and MRI images. An Exercise on familiarity with Cross Sectional Anatomy Go to the internet. Now that you have completed the exercises in this Unit and are familiar with various anatomical cross sectional slices for SPECT, CT and MRI, you should access the internet and visit the following websites for further experience in viewing transverse, sagittal and coronal images. The black and white images within the text of this Unit has a limited teaching capacity but you can appreciate the subject further through visual and interactive experience on the computer. Good examples to try: http://www.med.harvard.edu/AANLIB/home.html • This is an information resource for the central nervous system with normal and pathologic structure images, and multiplanar and vascular anatomy which integrates clinical information with MR, CT, and nuclear medicine SPECT and PET images. The atlas covers Cerebrovascular, Neoplastic, Degenerative and Inflammatory or Infectious Diseases. The project is made possible in part by the Departments of Radiology and Neurology at Brigham and Women's Hospital, Harvard Medical School, the Countway Library of Medicine, and the American Academy of Neurology http://www.lumen.luc.edu/lumen/meded/grossanatomy/x_sec/mainx_sec.htm • This site provides cross sectional CT and MRI interactive images of head and neck, thorax, abdomen, pelvis and upper and lower limb. You can choose your anatomical region and level of cross sectional slice, with or without labels and even test your knowledge. This anatomical atlas is provided by LUMEN CrossSection Tutorial as developed through Loyola University Chicago Stritch School of Medicine. 30 Other websites of interest include: http://www.anatomyatlases.org/HumanAnatomy/CrossSectionAtlas.shtml http://teaching.anatomy.auckland.ac.nz/atlas/abdomenthorax/intro/images.htm Go to your Workbook Sectional Anatomy and complete question 4 Key Points • • • Sagittal sections give information about the anterior/posterior and superior/inferior relationship of structures. Coronal sections give information about superior/inferior relationships of structures and medial/lateral relationships. Transverse or axial sections give information about anterior/posterior relationships and medial/lateral relationships. 31 Part 2 Introduction: Now that you have completed Part 1 you will be familiar with the terminology associated with cross sectional anatomy when describing the various planes at which images are projected. You have studied labelled diagrams depicting the sections of internal organs at different levels of the brain, thorax and pelvis and completed exercises recording your understanding of these features. With the fusion of SPECT and PET images with CT, we now need to broaden our understanding towards what we expect to visualize in normal PET/CT image and learn to distinguish normal anatomic variations from variations that indicate disease or injury. The Units: Clinical PET, SPECT and PET Physics and Principles of CT all emphazise the importance of quality assurance and how to avoid errors and misinformation. Variants and Pitfalls teaches you how to recognise normal variations and provides image examples of what can be seen if certain artefacts are experienced. When considering these aspects you are betters able to recognise abnormalities but first you need to be familiar with normal structures, organs and vessel locations and expected uptake of radiopharmaceuticals. DAT Cross Sectional program: website:…… This new learning resource is rich in features making it easier for you to learn, identify, and recall anatomic structures in cross‐section. You can step through the transverse, coronal and sagittal slices of normal FDG PET scans and associated CT or MRI images shown in sequence through multiple planes allowing you to identify anatomy on actual images through labels of important sites of interest within the brain, thorax and pelvis. There are self-assessment questions to test your understanding with feedback answers. At the completion of this exercise you should complete the assignment of Multiple Choice Questions. The results will be recorded as part of you final assessment. Objectives: • • On completion of the on-line exercise you will be able to Identify… Recognise… Time Check: Allow 6 hrs to complete this exercise on_line through the DAT website First perform the following Familiarity exercise: Go to: • • • http://www.med.harvard.edu/JPNM/chetan/ Try the various options: Normal Distribution Benign Pathological Variants Pitfalls and Artefacts 32 Prepare for an Exercise Go To your computer and log_on to the DAT website…… Enter your password …. Follow instructions ……………….. 33