Mechanical Waves: Applications in Medicine. How Elastography is Helping Doctors Avoid the Biopsy Needle

Transcription

1 Mechanical Wave: Application in Medicine How Elatography i Helping Doctor Avoid the Biopy Needle

2 Purpoe Thi leon i meant to increae tudent undertanding of mechanical wave and provide them with example of medical application of mechanical wave. Audience Thi leon i deigned for ue in an introductory high chool phyic cla. Leon Objective Upon completion of thi leon, tudent will be able to: ஃ explain the relationhip between a mechanical wave peed and the medium through which it i traveling. ஃ calculate wave peed given frequency and wavelength. ஃ decribe medical application of mechanical wave. Key Word elaticity, elatography, fibroi, palpation, hear wave Big Quetion Thi leon addree the Big Quetion What doe it mean to oberve? Standard Alignment ஃ Science and Engineering Practice ஃ SP2. Developing and uing model ஃ SP5. Uing mathematic and computational thinking ஃ SP8. Obtaining, evaluating, and communicating information ஃ MA Science and Technology/Engineering Standard (2016) ஃ HS-PS4-1. Ue mathematical repreentation to upport a claim regarding relationhip among the frequency, wavelength, and peed of wave traveling within variou media. Recognize that electromagnetic wave can travel through empty pace (without a medium) a compared to mechanical wave that require a medium. ஃ HS-PS4-5. Communicate technical information about how ome technological device ue the principle of wave behavior and wave interaction with matter to tranmit and capture information and energy. 1

3 ஃ NGSS Standard (2013) ஃ HS-PS-4-1. Ue mathematical repreentation to upport a claim regarding relationhip among the frequency, wavelength, and peed of wave traveling in variou media. ஃ HS-PS4-5. Communicate technical information about how ome technological device ue the principle of wave behavior and wave interaction with matter to tranmit and capture information and energy. ஃ Common Core Math/Language Art Standard CCSS.ELA-LITERACY.RST Cite pecific textual evidence to upport analyi of cience and technical text, attending to the precie detail of explanation or decription. Miconception Addreed Thi leon addree ome common miconception about wave, including: ஃ Mechanical wave do not need a medium to travel through. (Quetion 6) ஃ The frequency of mechanical wave change baed on the propertie of the material the wave travel through. (Quetion 11) Primary Source ஃ Bite Making Wave to Detect Illne baed on: ஃ Dhyani, Manih, Joeph Grajo, Atul K. Bhan, and Anthony E. Samir " Validation of Shear Wave Elatography Cutoff Value on the Superonic Aixplorer for Practical Clinical Ue in Liver Fibroi Staging. " Ultraound in Medicine and Biology 43(6): ஃ Parker, Kevin J., Marvin M. Doyley, and Deborah J. Ruben " Imaging the elatic propertie of tiue: The 20 year perpective." Phyic in Medicine and Biology 56(1):R1. ஃ Additional information provided by Mariappan, Yogeh, Kevin Glaer, and Richard Ehman Magnetic Reonance Elatography: A Review. Clinical Anatomy 23(5): Material ஃ Copie of the Student Handout and Science Bite for each tudent ஃ Mean to how liver image and occer ball video Time Thi leon hould take approximately one 50-minute cla period. 2

4 Student Prior Knowledge It would be helpful if tudent to have learned about propertie of mechanical wave and wave in general (period, frequency, amplitude, and peed). Intruction and Teacher Tip ஃ General Procedure ஃ Project the low motion video of a man being hit in the face by a occer ball ( ). You can how the entire video or jut from 3:43 to 4:25 to how the wave pule that travel through the man face when he i hit. ஃ Ak tudent to decribe what they notice about the man facial tiue in the moment after he i hit with the occer ball. Student hould ee that hi face i contorted. They may note that it look like a wave i traveling through hi face. If they don t, you may mention before giving tudent the tudent document. ஃ Provide each tudent with a copy of the tudent document. Have tudent read through the introduction and anwer Quetion 1 2. ஃ Review tudent repone for Quetion 1 2 with the cla. ஃ Have tudent read the Bite and repond to Quetion ஃ Project Figure 7 from "Magnetic Reonance Elatography: A Review." ஃ Paper: ஃ Direct Link to Figure: ஃ Help tudent develop an undertanding of the image. ஃ Tell tudent that the row how image of the ame liver (two different liver) and the column how image uing the ame technique. The firt column of image (a and d) how image of liver taken uing traditional MRI technique and the econd column (b and e) how image taken uing magnetic reonance elatography (MRE). Image c and f how tiffne etimate of the liver baed on the elatography data. Ak tudent to decribe what they ee in the image. The liver look nearly identical in image a and d, but the difference become clear with the elatography data. ஃ Tell tudent that another way reearcher look at elatography data i to meaure the hear modulu (an indication of rigidity) in kpa. The higher the kpa of a ubtance, the more rigid it i. Ak tudent if they can ue thi information to determine which liver i fibrotic (the bottom liver i fibrotic, there i a large area of highly rigid tiue due to liver cirrhoi). 3

5 ஃ Tip, Extenion, and Variation ஃ A an exploration before the leon, you can have tudent oberve the propertie of tuning fork. Have tudent gently hit the tine of the tuning fork with rubber mallet and ak them to decribe what happen when they touch the tine and what it feel like when they do. You can alo have tudent place a vibrating tuning fork in water to oberve what happen. Student hould realize that the tuning fork i vibrating. Thi will help them make the connection that mechanical wave are due to the diturbance of ome medium. If you wih to talk more about ound, you can decribe how the tuning fork caue the air molecule to vibrate. The vibration in the air caue the bone in the middle ear to vibrate. Senory neuron are timulated by the vibration and pa the ignal to the brain, which interpret the information a ound. ஃ To horten the leon, you can kip howing the tudent the image of the two liver from Magnetic Reonance Elatography: A review at the end of the leon. ஃ Many tudent have the miconception that the frequency of a wave change and not the wave peed when it goe through different media. Thi leon drive home the point that the frequency of a wave doen t change, but it peed doe a it move through material with different propertie. Take the time to emphaize thi point: A a liver get tiffer, the wave i able to travel more quickly, but the frequency of the wave doe not change. ஃ You may wih to how thi video about magnetic reonance elatography from the Mayo Clinic before you have tudent analyze the image from Magnetic Reonance Elatography: A review : Background Information and Reearch Detail ஃ In addition to diagnoing liver fibroi, elatography i being ued for the aement of breat cancer. Elatography ha been hown to increae doctor ability to ditinguih cancerou tumor from harmle lump. Thi i important becaue 8 out of 10 lump found in breat are not cancerou and over diagnoi lead to unneceary biopie. ஃ Elatography alo ha the advantage that it allow a phyician to meaure and track change in the tiue over time. For example, in patient with liver dieae, monitoring the elaticity of liver tiue can help doctor track the progreion of the dieae and determine the effectivene of treatment. ஃ The peed of mechanical wave i cloely tied to the medium elaticity and denity. A the rigidity of a ubtance increae the peed at which mechanical wave travel through it increae. A material that i more rigid ha particle that will return to their original poition fater than a material that i more flexible. If the particle return to their original poition fater, they are then able to move again fater. It i thi property that allow thee material to vibrate quicker. On the other hand, a the denity of a ubtance increae, the peed at which mechanical wave travel through it decreae. The elatic propertie of a ubtance tend to have a greater effect on mechanical wave peed and therefore even very dene material like gold allow mechanical wave to travel inide of them much more quickly than le dene material like air. 4

6 Big Quetion Dicuion Thi leon addree the Big Quetion What doe it mean to oberve? Specifically, tudent hould come to undertand that obervation are not limited to jut thing we experience with our five ene it i important to take multiple obervation of omething a omeone life might depend on repeatable obervation. If you chooe to delve into the Big Quetion, conider the following idea: ஃ When howing the initial video of the peron getting hit in the face with a occer ball, note how viewing that in high peed allowed u to ee the wave pule traveling through hi facial tiue. If we did not have that technology, we would not be able to make thoe obervation. ஃ When dicuing the MRI and elatography image of the two different liver, why ome obervation are more ueful than other in certain ituation. ஃ After tudent have completed the activity or if they are truggling with the lat quetion, prompt them with quetion uch a: ஃ What information doe palpation provide? How can elatography provide imilar information? Which one more directly involve one of our five ene? ஃ What advantage doe elatography have over palpation? ஃ How do doctor ue obervation to diagnoe patient? What limitation do thee obervation have? Anwer 1. Define elaticity in your own word. Give an example of a olid with high elaticity that i not mentioned in the introductory text. Sample anwer: Elaticity i a meaure of how well a material bounce back after being deformed. The egg white of a cooked egg or a piece of Spandex fabric i another example of a material that ha high elaticity. 2. What i palpation and why do doctor ue it? What are the limit of palpation a a diagnotic technique? Palpation involve phyically touching a peron tiue in order to ae it elaticity. Doctor perform palpation to ae the health of a tiue or organ. You normally can t or don t want to ue palpation on internal organ a that would endanger the patient. Palpation i alo not precie. Making Wave to Detect Illne 5

7 3. Decribe elatography in your own word. What are ome advantage of elatography over other type of medical diagnoi procedure uch a ultraound or a biopy? Cite pecific evidence from the text to upport your anwer. Elatography i the tudy of how elatic a ubtance i. Elatography i le invaive and afer than other type of procedure uch a biopie. A noted in the text, biopy can lead to internal bleed which put the life of the patient in danger. By uing elatography a doctor can avoid thoe complication. Additionally, elatography can alo reveal information that other procedure like ultraound and MRI can t. 4. A hear wave doe not jut travel on the urface of an object, but travel through the entire body of the object. Why do you think hear wave are ued to tudy body tiue intead of wave that jut exit on the urface of an object? Explain your anwer. Shear wave are ued to tudy body tiue intead of wave that jut exit on the urface, becaue if you only gather information about the urface of an organ you aren t capturing information about the entire organ. The organ could have a cancerou growth on the inide and you wouldn t know it if you only teted the urface of the organ. There are four type of eimic wave, the wave reponible for earthquake. Diagram of each type of wave are hown in Figure 1 below. Figure 1. The Four Main Type of Seimic Wave. Two type of eimic wave, -wave and p-wave, travel through Earth while Love wave and Rayleigh wave travel along Earth urface. S-wave and p-wave travel fater than Love and Rayleigh wave, but Love and Rayleigh wave tend to do the mot damage to tructure. 5. Examine the wave diagram in Figure 1. a. Which type or type of eimic wave are tranvere? Jutify your repone with evidence from Figure 1. S-wave, Love wave, and Rayleigh wave are all tranvere wave. A hown in Figure 1, for each of thee type of eimic wave, the direction particle in the medium move i perpendicular to the direction the wave i propagating. 6

8 b. Which type or type of eimic wave are longitudinal? Jutify your repone with evidence from Figure 1. P-wave are longitudinal wave. A hown in Figure 1, the direction particle in the medium move i parallel to the direction the p-wave i propagating. c. Which type of eimic wave i mot imilar to the hear wave ued in elatography? Jutify your anwer with evidence from Figure 1 and the Science Bite. A noted in the Science Bite, hear wave are tranvere wave and they travel through both the inner and outer part of the object. Thee propertie mot cloely match the -wave hown in Figure 1. The -wave are alo tranvere (the particle in the medium move perpendicular to the direction the wave move) and they travel through the body of the Earth, not jut the Earth urface. 6. A noted in the introduction, the wave ued in elatography are mechanical wave. What property or propertie of the wave ued in elatography make them mechanical wave? A mechanical wave i one that require a medium to travel though. The wave ued in elatography require a medium, uch a a patient liver, to travel through. 7. In your own word, decribe how hear wave elatography (SWE) data i collected. Firt, you create a hear wave inide of a patient by haking the organ or tiue you are intereted in. Then you take picture of the organ very quickly uing ome other technology like ultraound or MRI. Finally, you ue thoe image to determine the peed or length of the wave. 8. What do reearcher look for when they are diagnoing liver fibroi uing SWE? Why do they look for thi? Reearcher look for higher wave peed when they are diagnoing liver fibroi. They look for thee higher wave peed, becaue that i an indication of tiffer tiue and a a liver become fibrotic it get tiffer. 9. How did the reearcher ae the validity of SWE a compared to liver biopy? Cite pecific evidence from the text to upport your anwer. A decribed in the text, the reearcher performed both SWE and a liver biopy on over 300 patient. They compared having a 2.7 m/ wave peed in a patient liver to the reult of a liver biopy. They found that 95% of the time when a patient liver ha a wave peed of 2.7 m/ or above, the liver biopy alo indicated that the liver wa highly fibrotic. 10. Analyze the data in Table 1 to anwer the following quetion. a. Determine the wave peed for each of the wavelength provided. Show all work and include unit in your anwer. Trial 1: v = λ f = m 60 Hz = 2.87 m/ Trial 2: v = λ f = m 60 Hz = 2.86 m/ Trial 3: v = λ f = m 60 Hz = 2.65 m/ Trial 4: v = λ f = m 60 Hz = 2.53 m/ Trial 5: v = λ f = m 60 Hz = 2.80 m/ 7

9 b. Baed on your minimum wave peed value, doe the patient have evere liver fibroi? Explain your anwer. No, my minimum value i 2.53 m/ and the cut-off value for evere liver fibroi i 2.7 m/, o thi value would indicate that the patient doe not have evere liver fibroi. c. Take the average of your wave peed value. Baed on that information doe the patient have evere liver fibroi? Explain. / / / / / = 2.74 m/ 2.87 m m m m m 5 Ye, baed on the average wave peed, the patient doe have evere liver fibroi, becaue the average i higher than the cut-off value of 2.7 m/. d. Determine the median of your wave peed value. Baed on that information doe the patient have evere liver fibroi? Explain. The median wave peed value i 2.80 m/. Baed on thi value, the patient doe have evere liver fibroi a thi value i higher than the cut-off value of 2.7 m/. e. Do you think the patient ha evere liver fibroi? Provide evidence and reaoning for your claim. Ye, I do think the patient ha evere liver fibroi, becaue three of the experimental value are above the cut-off value for evere liver fibroi and the mean and median are alo above the cut-off value. Even though there are two experimental value below the cut-off value the evidence point to the patient having evere liver fibroi. f. Typically, when conducting an elatography analyi of omeone liver, the technician will take at leat ten different reading in up to three different location on the body. Why do the reult hown above demontrate the importance of taking multiple trial when conducting an experiment, epecially one ued in diagnoi? The reult above demontrate the importance of taking multiple trial, becaue if the technician only took one trial it might how that the patient doe not have evere liver fibroi when they actually do. For intance, Trial 3 and Trial 4 have wave peed value lower than the cut-off value for evere liver fibroi, but the ret of the trial indicate that the patient ha evere liver fibroi. If Trial 3 or Trial 4 wa the only meaurement the technician took they might wrongly diagnoe the patient a not having evere liver fibroi. When we are thinking about omeone health it i important to do everything we can to make an accurate diagnoi a it can have a large impact on their life. 8

10 The tudy decribed in the Bite invetigated the average peed of the hear wave in patient with varying level of liver fibroi, hown in the table below. Leat Fibrotic Mot Fibrotic 1.52 m/ 1.60 m/ 1.79 m/ 2.16 m/ 2.81 m/ Table 2. Average Shear Wave Speed in Liver with Different Level of Fibroi. Source: Dhyani et. al Examine Table 2 above. a. Decribe the trend in wave peed a the everity of liver fibroi increae. Why doe that make ene? Cite pecific evidence from the introduction and Bite. A the level of fibroi increae, o doe the wave peed. Thi make ene, becaue in the introduction we were told that a the tiffne of a material increae, o doe the peed of a mechanical wave in that material. In the Bite we are told that fibroi in the hardening of the liver, o a you have more fibroi your liver i getting tiffer. Therefore a the everity of the fibroi increae o hould the hear wave peed. Suppoe reearcher ued the Fibrocan to collect the data hown in Table 2. b. What would be the average wavelength of the hear wave in the leat fibrotic liver? λ = v 1.52 m f = / 50 Hz = m c. What would be the average wavelength of the hear wave in the mot fibrotic liver? λ = v 2.81 m f = / 50 Hz = m d. What i the relationhip between wavelength and wave peed? Why doe that make ene baed on the equation for wave peed? A wave peed increae, o doe wavelength if frequency i kept the ame. That make ene, becaue the equation for wave peed how that wavelength and wave peed are directly proportional. 12. Connect to the Big Quetion In thi leon, we learned how cientit ue their obervation to determine if omeone i ill. Compare and contrat the different type of obervation you learned about in thi leon. How doe thi change your peronal definition of oberve? What type of obervation hould doctor rely more on? Why do you think o? Sample anwer: There are pecific type of obervation doctor ue in order to diagnoe a patient. Thee obervation can be invaive, like a biopy or minimally o like uing elatography. They can alo be fairly complex like ultraound or MRI or omething a imple a feeling a tiue for difference in tiue tiffne. Often, we think of obervation a jut thing we ee, but there i o much more to obervation than jut what we can perceive with our eye. We need to ue the multitude of information available to u in order to make deciion. I 9

11 think doctor hould ue obervation that reliably diagnoe a patient a determining if a patient i actually ick or not and what illne they have i of the utmot importance when treating them. Where poible, doctor hould ue obervation that are minimally invaive a to minimize injury and dicomfort for patient. _v3: update to procedure for teacher Augut 2,