How to Read a Treasure Map – Part 2

The problem is not the problem, the problem is your attitude about the problem.

Jack Sparrow

Hello again guys…

Last time we saw why we, as clinicians, need to know how to read CT scan images, and what a CT scan is and works… Today we are going to finish our journey, explaining to you how to read and interpret the images…

Nothing special, nothing complex, nothing specific… Just a couple of notions nobody ever tells…

Let’s start…

How to Read CT Scan Images for Dummies

Ok then… Now that we’ve given you a brief overview of what a CT scan is, let’s go directly to the hot topic… How to look at and how to interpret CT scan images…

I think you all know the game “Where’s Waldo?”…

Well, reading CT images is something like it. You know what you are looking for (e.g. an abnormal mass, fat stranding, free fluid, etc…), but it may be hidden between other abnormal or unusual things. You need to look for the details and the nuances of grays… Sometimes things that seem pathological are not the source of the patient’s problem.

Returning to why it is important for surgeons to look at the images…

We have a different approach to the images compared to radiologists. The latter don’t have the specific overall picture of patients that we do after having examined them. They generally analyze the images using the same scheme, for example, liver, spleen, pancreas, kidneys, then esophagus, stomach, and so on. The process is mostly the same. On the contrary, surgeons know which are the possible differential diagnoses and we know which are the important information we need to decide the best management for that specific patient. This knowledge is fundamental when we read CT images… Basically, we know what we want.

The difference is the same as two people going to an Italian restaurant: the first wants to eat Italian food, and the second wants to eat pizza. Obviously, the second one has fewer choices, and he/she does not have to look at the entire menu to decide. Of course, this approach may have pros and cons, and that’s why radiologists are always useful.

So, when we approach CT scan images, we need to follow three basic steps:

• First: we must scroll the images grossly, in order to collect only macroscopic information, something clearly wrong at first sight (e.g. free fluid, free air, big masses, or obvious anomalies);
• Second: as we said earlier, we already have our clinical suspicions, so we know where to look and what to search for. Go there and examine it accurately. Is one of your clinical suspicions confirmed? Do you have alternatives? Remember that sometimes the problem is not just one, so check for all your diagnostic hypotheses;
• Third: now that you have an idea of what the patient has, look a little bit around for other important anomalies. Remember that the index disease may directly lead to consequences in other body areas… Look for them…

Let us make it clearer with an example…

You are called to examine a 23-year-old girl who arrived at the Emergency Room because of pain in the right iliac fossa, fever, nausea, vomiting, and occasional diarrhea.

On examination she has pain in the right iliac fossa, but no rebound tenderness.

Laboratory exams showed a mild leukocytosis and an increased CRP. The pregnancy test is negative.

The acute appendicitis scores are indeterminate, so ask for an abdominal ultrasound that shows only a little bit of free fluid near the cecum.

You call the ObsGyn who says that everything is fine.

Do you have any ideas? What are the possible diagnoses? Acute appendicitis? Right salpingitis? Terminal ileitis? Other?

Maybe the CT scan is far too much for this patient, but you sense that something’s wrong, so you ask for it anyway.

So then, let’s see the three steps we mentioned above:

• First (the overview): no pneumoperitoneum, small amount of free fluid in the Douglas pouch, and you see that something’s wrong in the right iliac fossa.
• Second (straight to the point): in this case the problem seems to be in the right iliac fossa. There you find a mass involving the cecum and the appendix, fat stranding all around, and enlarged lymph nodes. Based on your interpretation of the images, it may be an appendiceal mucocele or adenocarcinoma.
• Third (possible consequences): you need to ask yourself the question “which other anomalies may an appendiceal neoplasm lead to?” The answer is quite obvious, so you need to look for liver metastases and peritoneal carcinomatosis.

To read CT images is not difficult, but as everything it requires a lot of practice… And the more you train, the better you get.

Our advice is to always look at the CT scan images of your patients, whatever it is the reason they had a CT scan. Then, read the official report and compare your findings with those the radiologists had reported. If something is different or is missing between what you have seen and what the radiologist has, go back to the images and check again.

The more you repeat this “mantra”, the faster you become proficient in reading CT images.

However, always remember that you are not a radiologist… And there are some things to keep always in mind:

• Knowing how to read CT images is not mandatory, but is highly advisable, and it is an important weapon that you will have at your disposal… And four eyes are better than two.
• You have no obligation to find everything abnormal. You have to look at what you are interested in… Everything else is extra.
• Do not rush… Take your time and look accurately at the patient’s images. Looking at them quickly is not useful to anybody… Not to you, nor the patient…
• This post is not meant to be a proclamation against radiologists!!! Always remember that if you miss something, the radiologist is there to save your sorry ass. So, when you are skilled enough in interpreting CT images, do not think you are allowed to mistreat the radiologists. They are just strange people, but they deserve our respect (and compassion).

CT Scan & Patients Hemodynamically Unstable

To conclude our brief journey into this ocean of images, we want to leave you one last concept…

In patients hemodynamically unstable, the CT scan has obtained many different nicknames… The doughnut of doom, the tunnel of death, etc…

However, is it always true?

Well, as in most multiple-choice questions, usually the answer with “always” inside is wrong…

Firstly, we have to understand some details:

1. Is the patient in shock? Is he/she hemodynamically unstable? What does hemodynamically unstable mean? Have you considered the “responsiveness” concept?
2. What kind of shock are we facing? To understand better the concept of shock and the different types, read our previous post.
3. How should the CT scan be performed on that precise patient? Where is the CT? Time is life…

To keep this as simple as possible, we can affirm that we, as surgeons, face basically two kinds of shock: the hemorrhagic shock, and the septic shock.

The pathophysiology behind these two shocks is completely different: the first one is secondary to a massive loss of blood, and the second one is to a massive vasodilation. Consequently, the main treatment to resolve the status of shock differs between the two.

In the case of active bleeding, fluids, and blood do not work if the bleeding is not stopped. So, the first aim is to stop the bleeding, and to achieve that surgery is needed, and no time must be lost. In fact, it is clearly stated by Clarke JR, et al. that in hypotensive trauma patients the probability of death increases by 1% for each 3 minutes spent in the Emergency Department. However, more recently, this dogma that CT scans must not be performed in hemodynamically unstable trauma patients has been placed in question by Ordonez CA, et al. In fact, they conclude that a proper patient selection should be performed. Moreover, we want to add that many details must be taken into account to decide whether to perform a CT scan on an unstable trauma patient (e.g. personnel expertise on trauma, hospital/department distances, time required, etc…).

On the other hand, in the case of sepsis, the hemodynamic instability can be treated effectively with fluids and vasopressors. In this second case, we have more time, and the so-called “source control” can be delayed. You can read more about sepsis and septic shock in our previous post.

Ok, guys… We have also concluded this brief but intense journey…

We really hope you have enjoyed it as much as we did…

See you next time, and take care!!!

References

1. Murphy A. Hounsfield unit. Radiopaedia. Accessed on September 10, 2023. Available at [https://radiopaedia.org/articles/hounsfield-unit?lang=us].
2. European Society of Urogenital Radiology. ESUR Guidelines on Contrast Agents. Accessed on September 10, 2023. Available at [https://www.esur.org/esur-guidelines-on-contrast-agents/].
3. Clarke JR, et al. Time to laparotomy for intra-abdominal bleeding from trauma does affect survival for delays up to 90 minutes. J Trauma 2002;52:420-5.
4. Ordonez CA, et al. Computed tomography in hemodynamically unstable severely injured blunt and penetrating trauma patients. J Trauma Acute Care Surg 2016;80:597-602.
5. Hecker A, et al. Intra-abdominal sepsis: new definitions and current clinical standards. Langenbeck’s Archives of Surgery 2019;404:257-71.

How to Cite This Post

Bellio G, Sandano M, Mastronardi M, Biloslavo A, Marrano E. How to Read a Treasure Map – Part 2. Surgical Pizza. Published on October 29, 2023. Accessed on March 14, 2025. Available at [https://surgicalpizza.org/imaging/how-to-read-a-treasure-map-part-2/].