{
  "id": 182376,
  "title": "Pulmonary Embolism: A Brief Intro",
  "url": "/competitions/rsna-str-pulmonary-embolism-detection/discussion/182376",
  "author_name": "Ian Pan",
  "post_date": "2020-09-12T13:46:17.830000",
  "votes": 108,
  "comment_count": 11,
  "views": 0,
  "content": "<h1>What is Pulmonary Embolism?</h1>\n<p>A pulmonary embolism (PE) is a blood clot in the blood vessels of the lungs that can be potentially life-threatening. PEs typically arise from blood clots in the leg veins (deep vein thromboses, or DVTs) that dislodge and become trapped in the pulmonary vasculature. The clinical presentation of PE can vary from asymptomatic to severe illness requiring intensive care (shock, cardiac arrest, etc). </p>\n<h1>How is PE diagnosed?</h1>\n<p>There are various tools for diagnosing PE; however, current practice relies primarily on CT angiography. Intravenous contrast is administered through the patient's veins just prior to obtaining the CT, and the CT scan is timed to obtain images when the contrast is primarily in the pulmonary blood vessels. Note: this is where quality issues can occur. Sometimes the timing of the scan is off, resulting in a suboptimal scan. This can result in non-diagnostic or equivocal studies. In addition, if the patient is moving a lot or has metal in their body, this can cause artifacts which may obscure a clot. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/17056972/2ef2ae41c8a0b5a070aa21140a14e0_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>This image shows a single axial slice of a CT pulmonary angiogram (CTPA or CTPE) at this level of the pulmonary trunk. The pulmonary trunk is a major blood vessel that comes from the right side of your heart to supply blood to your lungs. Note how bright the blood vessels are - this is due to the intravenous contrast. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/36787671/60da4496798220ab2a3b52f1978e49_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>In this image, notice how there are \"filling defects\" in the pulmonary trunk. Unlike the previous image, there are areas in the blood vessels that are more gray. This is evidence of a pulmonary embolism in the blood vessel, as the blood clot prevents the contrast from filling up the entire vessel. This type of PE would be a central PE in our dataset (it is in the central blood vessel of the lungs).</p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/17483790/2cc61c62b20f31c98b8b9df642b4d9_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>Note that PEs can occur anywhere in the lung vasculature, which is very extensive and resembles a tree. However, the finding we are looking for is the same: filling detects. Patients can have multiple PEs across both lungs: hence, we have labels for right-sided, left-sided, and central PEs, but these are <strong>not</strong> mutually exclusive. </p>\n<h1>Acute vs. Chronic PE</h1>\n<p>Not all PEs result in symptoms. Generally, acute (sudden-onset) PEs are more likely to cause symptoms, as your body has not had time to adapt to the presence of a clot. There are imaging findings that can distinguish acute from chronic PEs, but this can be challenging to discern. </p>\n<h1>Right Ventricle/Left Ventricle Ratio</h1>\n<p>Your heart has 4 chambers. The muscular chambers that do most of the pumping are known as the ventricles. Your right ventricle pumps blood to your lungs; your left ventricle pumps blood to the rest of your body. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/17057333/137a759a3fe838a0e5d7f959a6050f_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>Remember - everything is flipped in radiology, so the RIGHT SIDE of the body is on the LEFT, and vice versa. That giant ball just off-center in this image is the heart. Normally, your left ventricle (lower right) is larger than your right ventricle (upper left), like in this image. This is because the left ventricle has a much harder job to do: pump body throughout the entire body versus just the lungs. However, having a PE can put a big strain on the right side of your heart. Intuitively, this makes sense - if you have a blockage in the blood vessels in your lungs, the right side of your heart has to work a lot harder to try and pump blood through the obstruction. </p>\n<p>Sometimes, we can see evidence of this on the CT - we call this right heart strain. This suggests a more severe PE because the blood clot is forcing your right heart to work harder and causing blood to become backed up into the right ventricle (it's just plumbing!). We can measure the ratio of diameters of the right ventricle to the left ventricle to see if this is high. A high ratio is suggestive of right heart strain. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/807719/db43f21911fc4f6f8522ca7a3af124_gallery.jpg\" alt=\"enter image description here\"></p>\n<p>Notice how the upper left part (right ventricle) is much larger than the lower right part (left ventricle). This patient is having a severe PE causing significant right heart strain. </p>\n<p>Because of its importance as a prognostic indicator, detecting RV/LV ratio &gt; 1 in this competition is weighed most heavily across all the other classes. Please note that this is a 3D image. The proper way to compute RV/LV ratio is to find the maximum diameter across all slices. The maximum diameters of each ventricle are usually on different slices.</p>\n<h1>Treatment of PE</h1>\n<p>Treatment depends on the severity of the clot. Typically, we will use blood thinners, either IV or oral. In severe cases, we may attempt catheter-directed thrombolysis. An interventional radiologist inserts a catheter into the pulmonary blood vessels to deliver clot-busting medication directly to the clot. Rarely, surgery may be required. </p>",
  "messages": [
    {
      "id": 1007783,
      "postDate": "2020-09-12T13:46:17.830Z",
      "content": "<h1>What is Pulmonary Embolism?</h1>\n<p>A pulmonary embolism (PE) is a blood clot in the blood vessels of the lungs that can be potentially life-threatening. PEs typically arise from blood clots in the leg veins (deep vein thromboses, or DVTs) that dislodge and become trapped in the pulmonary vasculature. The clinical presentation of PE can vary from asymptomatic to severe illness requiring intensive care (shock, cardiac arrest, etc). </p>\n<h1>How is PE diagnosed?</h1>\n<p>There are various tools for diagnosing PE; however, current practice relies primarily on CT angiography. Intravenous contrast is administered through the patient's veins just prior to obtaining the CT, and the CT scan is timed to obtain images when the contrast is primarily in the pulmonary blood vessels. Note: this is where quality issues can occur. Sometimes the timing of the scan is off, resulting in a suboptimal scan. This can result in non-diagnostic or equivocal studies. In addition, if the patient is moving a lot or has metal in their body, this can cause artifacts which may obscure a clot. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/17056972/2ef2ae41c8a0b5a070aa21140a14e0_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>This image shows a single axial slice of a CT pulmonary angiogram (CTPA or CTPE) at this level of the pulmonary trunk. The pulmonary trunk is a major blood vessel that comes from the right side of your heart to supply blood to your lungs. Note how bright the blood vessels are - this is due to the intravenous contrast. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/36787671/60da4496798220ab2a3b52f1978e49_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>In this image, notice how there are \"filling defects\" in the pulmonary trunk. Unlike the previous image, there are areas in the blood vessels that are more gray. This is evidence of a pulmonary embolism in the blood vessel, as the blood clot prevents the contrast from filling up the entire vessel. This type of PE would be a central PE in our dataset (it is in the central blood vessel of the lungs).</p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/17483790/2cc61c62b20f31c98b8b9df642b4d9_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>Note that PEs can occur anywhere in the lung vasculature, which is very extensive and resembles a tree. However, the finding we are looking for is the same: filling detects. Patients can have multiple PEs across both lungs: hence, we have labels for right-sided, left-sided, and central PEs, but these are <strong>not</strong> mutually exclusive. </p>\n<h1>Acute vs. Chronic PE</h1>\n<p>Not all PEs result in symptoms. Generally, acute (sudden-onset) PEs are more likely to cause symptoms, as your body has not had time to adapt to the presence of a clot. There are imaging findings that can distinguish acute from chronic PEs, but this can be challenging to discern. </p>\n<h1>Right Ventricle/Left Ventricle Ratio</h1>\n<p>Your heart has 4 chambers. The muscular chambers that do most of the pumping are known as the ventricles. Your right ventricle pumps blood to your lungs; your left ventricle pumps blood to the rest of your body. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/17057333/137a759a3fe838a0e5d7f959a6050f_gallery.jpeg\" alt=\"enter image description here\"></p>\n<p>Remember - everything is flipped in radiology, so the RIGHT SIDE of the body is on the LEFT, and vice versa. That giant ball just off-center in this image is the heart. Normally, your left ventricle (lower right) is larger than your right ventricle (upper left), like in this image. This is because the left ventricle has a much harder job to do: pump body throughout the entire body versus just the lungs. However, having a PE can put a big strain on the right side of your heart. Intuitively, this makes sense - if you have a blockage in the blood vessels in your lungs, the right side of your heart has to work a lot harder to try and pump blood through the obstruction. </p>\n<p>Sometimes, we can see evidence of this on the CT - we call this right heart strain. This suggests a more severe PE because the blood clot is forcing your right heart to work harder and causing blood to become backed up into the right ventricle (it's just plumbing!). We can measure the ratio of diameters of the right ventricle to the left ventricle to see if this is high. A high ratio is suggestive of right heart strain. </p>\n<p><img src=\"https://prod-images-static.radiopaedia.org/images/807719/db43f21911fc4f6f8522ca7a3af124_gallery.jpg\" alt=\"enter image description here\"></p>\n<p>Notice how the upper left part (right ventricle) is much larger than the lower right part (left ventricle). This patient is having a severe PE causing significant right heart strain. </p>\n<p>Because of its importance as a prognostic indicator, detecting RV/LV ratio &gt; 1 in this competition is weighed most heavily across all the other classes. Please note that this is a 3D image. The proper way to compute RV/LV ratio is to find the maximum diameter across all slices. The maximum diameters of each ventricle are usually on different slices.</p>\n<h1>Treatment of PE</h1>\n<p>Treatment depends on the severity of the clot. Typically, we will use blood thinners, either IV or oral. In severe cases, we may attempt catheter-directed thrombolysis. An interventional radiologist inserts a catheter into the pulmonary blood vessels to deliver clot-busting medication directly to the clot. Rarely, surgery may be required. </p>",
      "rawMarkdown": "# What is Pulmonary Embolism?\n\nA pulmonary embolism (PE) is a blood clot in the blood vessels of the lungs that can be potentially life-threatening. PEs typically arise from blood clots in the leg veins (deep vein thromboses, or DVTs) that dislodge and become trapped in the pulmonary vasculature. The clinical presentation of PE can vary from asymptomatic to severe illness requiring intensive care (shock, cardiac arrest, etc). \n\n# How is PE diagnosed?\nThere are various tools for diagnosing PE; however, current practice relies primarily on CT angiography. Intravenous contrast is administered through the patient's veins just prior to obtaining the CT, and the CT scan is timed to obtain images when the contrast is primarily in the pulmonary blood vessels. Note: this is where quality issues can occur. Sometimes the timing of the scan is off, resulting in a suboptimal scan. This can result in non-diagnostic or equivocal studies. In addition, if the patient is moving a lot or has metal in their body, this can cause artifacts which may obscure a clot. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/17056972/2ef2ae41c8a0b5a070aa21140a14e0_gallery.jpeg)\n\nThis image shows a single axial slice of a CT pulmonary angiogram (CTPA or CTPE) at this level of the pulmonary trunk. The pulmonary trunk is a major blood vessel that comes from the right side of your heart to supply blood to your lungs. Note how bright the blood vessels are - this is due to the intravenous contrast. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/36787671/60da4496798220ab2a3b52f1978e49_gallery.jpeg)\n\nIn this image, notice how there are \"filling defects\" in the pulmonary trunk. Unlike the previous image, there are areas in the blood vessels that are more gray. This is evidence of a pulmonary embolism in the blood vessel, as the blood clot prevents the contrast from filling up the entire vessel. This type of PE would be a central PE in our dataset (it is in the central blood vessel of the lungs).\n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/17483790/2cc61c62b20f31c98b8b9df642b4d9_gallery.jpeg)\n\nNote that PEs can occur anywhere in the lung vasculature, which is very extensive and resembles a tree. However, the finding we are looking for is the same: filling detects. Patients can have multiple PEs across both lungs: hence, we have labels for right-sided, left-sided, and central PEs, but these are **not** mutually exclusive. \n\n# Acute vs. Chronic PE\nNot all PEs result in symptoms. Generally, acute (sudden-onset) PEs are more likely to cause symptoms, as your body has not had time to adapt to the presence of a clot. There are imaging findings that can distinguish acute from chronic PEs, but this can be challenging to discern. \n\n# Right Ventricle/Left Ventricle Ratio\nYour heart has 4 chambers. The muscular chambers that do most of the pumping are known as the ventricles. Your right ventricle pumps blood to your lungs; your left ventricle pumps blood to the rest of your body. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/17057333/137a759a3fe838a0e5d7f959a6050f_gallery.jpeg)\n\nRemember - everything is flipped in radiology, so the RIGHT SIDE of the body is on the LEFT, and vice versa. That giant ball just off-center in this image is the heart. Normally, your left ventricle (lower right) is larger than your right ventricle (upper left), like in this image. This is because the left ventricle has a much harder job to do: pump body throughout the entire body versus just the lungs. However, having a PE can put a big strain on the right side of your heart. Intuitively, this makes sense - if you have a blockage in the blood vessels in your lungs, the right side of your heart has to work a lot harder to try and pump blood through the obstruction. \n\nSometimes, we can see evidence of this on the CT - we call this right heart strain. This suggests a more severe PE because the blood clot is forcing your right heart to work harder and causing blood to become backed up into the right ventricle (it's just plumbing!). We can measure the ratio of diameters of the right ventricle to the left ventricle to see if this is high. A high ratio is suggestive of right heart strain. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/807719/db43f21911fc4f6f8522ca7a3af124_gallery.jpg)\n\nNotice how the upper left part (right ventricle) is much larger than the lower right part (left ventricle). This patient is having a severe PE causing significant right heart strain. \n\nBecause of its importance as a prognostic indicator, detecting RV/LV ratio > 1 in this competition is weighed most heavily across all the other classes. Please note that this is a 3D image. The proper way to compute RV/LV ratio is to find the maximum diameter across all slices. The maximum diameters of each ventricle are usually on different slices.\n\n# Treatment of PE\nTreatment depends on the severity of the clot. Typically, we will use blood thinners, either IV or oral. In severe cases, we may attempt catheter-directed thrombolysis. An interventional radiologist inserts a catheter into the pulmonary blood vessels to deliver clot-busting medication directly to the clot. Rarely, surgery may be required. ",
      "votes": 107
    },
    {
      "id": 1045999,
      "postDate": "2020-10-11T08:26:36.227Z",
      "content": "<p>Great Summary - Thank you for this.<br>\nI couldn't initially understand which part of the CT scan is the Pulmonary Trunk - Maybe this image i got off the net can help others too.</p>\n<p><img src=\"https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F4822473%2Fb9729265f377f672ffba9ffc206192a5%2FLung%20CTScan.jpg?generation=1602404662214347&amp;alt=media\" alt=\"\"></p>",
      "rawMarkdown": "Great Summary - Thank you for this.\nI couldn't initially understand which part of the CT scan is the Pulmonary Trunk - Maybe this image i got off the net can help others too.\n\n![](https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F4822473%2Fb9729265f377f672ffba9ffc206192a5%2FLung%20CTScan.jpg?generation=1602404662214347&alt=media)",
      "votes": 3
    },
    {
      "id": 1050915,
      "postDate": "2020-10-15T22:11:42.053Z",
      "content": "<p>This is really interesting. I always love these competitions that push you to learn more than just data science. Thank you, Dr. Ian, for sharing your knowledge with us.</p>",
      "rawMarkdown": "This is really interesting. I always love these competitions that push you to learn more than just data science. Thank you, Dr. Ian, for sharing your knowledge with us.",
      "votes": 1
    },
    {
      "id": 1009115,
      "postDate": "2020-09-13T16:52:06.807Z",
      "content": "<p>Thanks a lot, Dr. <a href=\"https://www.kaggle.com/vaillant\" target=\"_blank\">@vaillant</a>. <br>\nThis discussion is so insightful that, it cleared several of my confusion regarding the whole CT angiogram understanding process. I would like to borrow some of your content to update my notebooks and discussions if that is ok. </p>",
      "rawMarkdown": "Thanks a lot, Dr. @vaillant. \nThis discussion is so insightful that, it cleared several of my confusion regarding the whole CT angiogram understanding process. I would like to borrow some of your content to update my notebooks and discussions if that is ok. ",
      "votes": 1,
      "replies": [
        {
          "id": 1009177,
          "postDate": "2020-09-13T17:50:26.260Z",
          "content": "<p>Of course, no problem! Feel free.</p>",
          "rawMarkdown": "Of course, no problem! Feel free.",
          "votes": 2
        },
        {
          "id": 1009181,
          "postDate": "2020-09-13T17:55:59.423Z",
          "content": "<p>Thanks a lot, Doctor <a href=\"https://www.kaggle.com/vaillant\" target=\"_blank\">@vaillant</a> <br>\nCan you provide me some additional materials like a document or a chapter of book on reading CTPE or CTPA? If yes, Here is my mail address:  <a>redwankarim@iut-dhaka.edu</a></p>",
          "rawMarkdown": "Thanks a lot, Doctor @vaillant \nCan you provide me some additional materials like a document or a chapter of book on reading CTPE or CTPA? If yes, Here is my mail address:  redwankarim@iut-dhaka.edu",
          "votes": 1
        }
      ]
    },
    {
      "id": 1008866,
      "postDate": "2020-09-13T13:00:02.617Z",
      "content": "<p>Thanks for your domain knowledge, doctor Ian!</p>",
      "rawMarkdown": "Thanks for your domain knowledge, doctor Ian!",
      "votes": 2
    },
    {
      "id": 1028881,
      "postDate": "2020-09-27T09:36:15.417Z",
      "content": "<p>Great knowledge introduction doctor!</p>",
      "rawMarkdown": "Great knowledge introduction doctor!"
    },
    {
      "id": 1009813,
      "postDate": "2020-09-14T08:51:26.690Z",
      "content": "<p>Thanks for your domain knowledge, doctor Ian!</p>\n<p>I usually can't tell the left or right in a CT image.<br>\nSo, it seems like looking at yourself in a mirror.</p>",
      "rawMarkdown": "Thanks for your domain knowledge, doctor Ian!\n\nI usually can't tell the left or right in a CT image.\nSo, it seems like looking at yourself in a mirror.\n\n"
    },
    {
      "id": 1009695,
      "postDate": "2020-09-14T07:12:45.570Z",
      "content": "<p>Thanks for your knowledge, it helped me a lot!!</p>",
      "rawMarkdown": "Thanks for your knowledge, it helped me a lot!!"
    },
    {
      "id": 1030848,
      "postDate": "2020-09-29T03:39:02.343Z",
      "content": "<p>Much needed explanation. Thanks.</p>",
      "rawMarkdown": "Much needed explanation. Thanks."
    },
    {
      "id": 1015367,
      "postDate": "2020-09-18T06:30:15.647Z",
      "content": "<p>Very insightful. Thank you !</p>",
      "rawMarkdown": "Very insightful. Thank you !"
    }
  ],
  "comments": [
    {
      "id": 1045999,
      "author_name": "Vee",
      "author_url": "",
      "post_date": "2020-10-11T08:26:36.227000",
      "content": "<p>Great Summary - Thank you for this.<br>\nI couldn't initially understand which part of the CT scan is the Pulmonary Trunk - Maybe this image i got off the net can help others too.</p>\n<p><img src=\"https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F4822473%2Fb9729265f377f672ffba9ffc206192a5%2FLung%20CTScan.jpg?generation=1602404662214347&amp;alt=media\" alt=\"\"></p>",
      "votes": 3,
      "replies": []
    },
    {
      "id": 1050915,
      "author_name": "DarkCube",
      "author_url": "",
      "post_date": "2020-10-15T22:11:42.053000",
      "content": "<p>This is really interesting. I always love these competitions that push you to learn more than just data science. Thank you, Dr. Ian, for sharing your knowledge with us.</p>",
      "votes": 1,
      "replies": []
    },
    {
      "id": 1009115,
      "author_name": "Redwan Sony",
      "author_url": "",
      "post_date": "2020-09-13T16:52:06.807000",
      "content": "<p>Thanks a lot, Dr. <a href=\"https://www.kaggle.com/vaillant\" target=\"_blank\">@vaillant</a>. <br>\nThis discussion is so insightful that, it cleared several of my confusion regarding the whole CT angiogram understanding process. I would like to borrow some of your content to update my notebooks and discussions if that is ok. </p>",
      "votes": 1,
      "replies": [
        {
          "id": 1009177,
          "author_name": "Ian Pan",
          "author_url": "",
          "post_date": "2020-09-13T17:50:26.260000",
          "content": "<p>Of course, no problem! Feel free.</p>",
          "votes": 2,
          "replies": []
        },
        {
          "id": 1009181,
          "author_name": "Redwan Sony",
          "author_url": "",
          "post_date": "2020-09-13T17:55:59.423000",
          "content": "<p>Thanks a lot, Doctor <a href=\"https://www.kaggle.com/vaillant\" target=\"_blank\">@vaillant</a> <br>\nCan you provide me some additional materials like a document or a chapter of book on reading CTPE or CTPA? If yes, Here is my mail address:  <a>redwankarim@iut-dhaka.edu</a></p>",
          "votes": 1,
          "replies": []
        }
      ]
    },
    {
      "id": 1008866,
      "author_name": "Qishen Ha",
      "author_url": "",
      "post_date": "2020-09-13T13:00:02.617000",
      "content": "<p>Thanks for your domain knowledge, doctor Ian!</p>",
      "votes": 2,
      "replies": []
    },
    {
      "id": 1028881,
      "author_name": "豆柴金鯱",
      "author_url": "",
      "post_date": "2020-09-27T09:36:15.417000",
      "content": "<p>Great knowledge introduction doctor!</p>",
      "votes": 0,
      "replies": []
    },
    {
      "id": 1009813,
      "author_name": "qzw",
      "author_url": "",
      "post_date": "2020-09-14T08:51:26.690000",
      "content": "<p>Thanks for your domain knowledge, doctor Ian!</p>\n<p>I usually can't tell the left or right in a CT image.<br>\nSo, it seems like looking at yourself in a mirror.</p>",
      "votes": 0,
      "replies": []
    },
    {
      "id": 1009695,
      "author_name": "Ryo-F",
      "author_url": "",
      "post_date": "2020-09-14T07:12:45.570000",
      "content": "<p>Thanks for your knowledge, it helped me a lot!!</p>",
      "votes": 0,
      "replies": []
    },
    {
      "id": 1030848,
      "author_name": "Aayush Kandpal",
      "author_url": "",
      "post_date": "2020-09-29T03:39:02.343000",
      "content": "<p>Much needed explanation. Thanks.</p>",
      "votes": 0,
      "replies": []
    },
    {
      "id": 1015367,
      "author_name": "Ronaldo S.A. Batista",
      "author_url": "",
      "post_date": "2020-09-18T06:30:15.647000",
      "content": "<p>Very insightful. Thank you !</p>",
      "votes": 0,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "1007783": "# What is Pulmonary Embolism?\n\nA pulmonary embolism (PE) is a blood clot in the blood vessels of the lungs that can be potentially life-threatening. PEs typically arise from blood clots in the leg veins (deep vein thromboses, or DVTs) that dislodge and become trapped in the pulmonary vasculature. The clinical presentation of PE can vary from asymptomatic to severe illness requiring intensive care (shock, cardiac arrest, etc). \n\n# How is PE diagnosed?\nThere are various tools for diagnosing PE; however, current practice relies primarily on CT angiography. Intravenous contrast is administered through the patient's veins just prior to obtaining the CT, and the CT scan is timed to obtain images when the contrast is primarily in the pulmonary blood vessels. Note: this is where quality issues can occur. Sometimes the timing of the scan is off, resulting in a suboptimal scan. This can result in non-diagnostic or equivocal studies. In addition, if the patient is moving a lot or has metal in their body, this can cause artifacts which may obscure a clot. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/17056972/2ef2ae41c8a0b5a070aa21140a14e0_gallery.jpeg)\n\nThis image shows a single axial slice of a CT pulmonary angiogram (CTPA or CTPE) at this level of the pulmonary trunk. The pulmonary trunk is a major blood vessel that comes from the right side of your heart to supply blood to your lungs. Note how bright the blood vessels are - this is due to the intravenous contrast. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/36787671/60da4496798220ab2a3b52f1978e49_gallery.jpeg)\n\nIn this image, notice how there are \"filling defects\" in the pulmonary trunk. Unlike the previous image, there are areas in the blood vessels that are more gray. This is evidence of a pulmonary embolism in the blood vessel, as the blood clot prevents the contrast from filling up the entire vessel. This type of PE would be a central PE in our dataset (it is in the central blood vessel of the lungs).\n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/17483790/2cc61c62b20f31c98b8b9df642b4d9_gallery.jpeg)\n\nNote that PEs can occur anywhere in the lung vasculature, which is very extensive and resembles a tree. However, the finding we are looking for is the same: filling detects. Patients can have multiple PEs across both lungs: hence, we have labels for right-sided, left-sided, and central PEs, but these are **not** mutually exclusive. \n\n# Acute vs. Chronic PE\nNot all PEs result in symptoms. Generally, acute (sudden-onset) PEs are more likely to cause symptoms, as your body has not had time to adapt to the presence of a clot. There are imaging findings that can distinguish acute from chronic PEs, but this can be challenging to discern. \n\n# Right Ventricle/Left Ventricle Ratio\nYour heart has 4 chambers. The muscular chambers that do most of the pumping are known as the ventricles. Your right ventricle pumps blood to your lungs; your left ventricle pumps blood to the rest of your body. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/17057333/137a759a3fe838a0e5d7f959a6050f_gallery.jpeg)\n\nRemember - everything is flipped in radiology, so the RIGHT SIDE of the body is on the LEFT, and vice versa. That giant ball just off-center in this image is the heart. Normally, your left ventricle (lower right) is larger than your right ventricle (upper left), like in this image. This is because the left ventricle has a much harder job to do: pump body throughout the entire body versus just the lungs. However, having a PE can put a big strain on the right side of your heart. Intuitively, this makes sense - if you have a blockage in the blood vessels in your lungs, the right side of your heart has to work a lot harder to try and pump blood through the obstruction. \n\nSometimes, we can see evidence of this on the CT - we call this right heart strain. This suggests a more severe PE because the blood clot is forcing your right heart to work harder and causing blood to become backed up into the right ventricle (it's just plumbing!). We can measure the ratio of diameters of the right ventricle to the left ventricle to see if this is high. A high ratio is suggestive of right heart strain. \n\n![enter image description here](https://prod-images-static.radiopaedia.org/images/807719/db43f21911fc4f6f8522ca7a3af124_gallery.jpg)\n\nNotice how the upper left part (right ventricle) is much larger than the lower right part (left ventricle). This patient is having a severe PE causing significant right heart strain. \n\nBecause of its importance as a prognostic indicator, detecting RV/LV ratio > 1 in this competition is weighed most heavily across all the other classes. Please note that this is a 3D image. The proper way to compute RV/LV ratio is to find the maximum diameter across all slices. The maximum diameters of each ventricle are usually on different slices.\n\n# Treatment of PE\nTreatment depends on the severity of the clot. Typically, we will use blood thinners, either IV or oral. In severe cases, we may attempt catheter-directed thrombolysis. An interventional radiologist inserts a catheter into the pulmonary blood vessels to deliver clot-busting medication directly to the clot. Rarely, surgery may be required. ",
    "1045999": "Great Summary - Thank you for this.\nI couldn't initially understand which part of the CT scan is the Pulmonary Trunk - Maybe this image i got off the net can help others too.\n\n![](https://www.googleapis.com/download/storage/v1/b/kaggle-forum-message-attachments/o/inbox%2F4822473%2Fb9729265f377f672ffba9ffc206192a5%2FLung%20CTScan.jpg?generation=1602404662214347&alt=media)",
    "1050915": "This is really interesting. I always love these competitions that push you to learn more than just data science. Thank you, Dr. Ian, for sharing your knowledge with us.",
    "1009115": "Thanks a lot, Dr. @vaillant. \nThis discussion is so insightful that, it cleared several of my confusion regarding the whole CT angiogram understanding process. I would like to borrow some of your content to update my notebooks and discussions if that is ok. ",
    "1008866": "Thanks for your domain knowledge, doctor Ian!",
    "1028881": "Great knowledge introduction doctor!",
    "1009813": "Thanks for your domain knowledge, doctor Ian!\n\nI usually can't tell the left or right in a CT image.\nSo, it seems like looking at yourself in a mirror.\n\n",
    "1009695": "Thanks for your knowledge, it helped me a lot!!",
    "1030848": "Much needed explanation. Thanks.",
    "1015367": "Very insightful. Thank you !"
  }
}