Radiopaedia Blog

Everyone knows that radiology is a discipline of images. Perfectly penetrated chest radiographs, speckled T2 hyperintensities in the liver parenchyma, subtle fat stranding around the appendix on a noncontrast CT... these images are the domain of the radiologist.

But there is another domain of radiology that doesn't always receive enough attention: the words of imaging. One could even think of the duties of the radiologist as threefold:

1. to obtain a high quality image
2. to medically interpret the image
3. to express the image and interpretation in words

Each is important.

When I listed the imaging findings above, your mind probably pictured them immediately. The words were a mediator between your mind and the image. Although the language of radiology is highly mimetic (representational of an "objective" reality, rather than creative), it is inevitable that the way in which we structure a report will change the way our reader looks at an image. A report is not a shadow of an image (a shadow of a shadow), but a lens through which an image is read. The way a report is structured can either obscure an image or shed light on it.  

Since this is the case, attention to the language of radiology is not optional. Words must be used carefully and deliberately in order to achieve the effect we want.

Active vs. passive voice

One effect that should be deliberately chosen is when to use the active voice and when to use the passive voice when writing a report.

The active voice is the more common way of constructing an English sentence:

• "I dictated the report" (subject - verb - object)

The passive voice often implies the subject:

• "The report was dictated" ("object" - verb)

This passive construction raises the question: "by whom"?  The report was dictated... by whom?

The passive construction is endemic to much scientific writing and by extension, to radiology reports. Take these common radiology phrases as examples:

• ... was seen / can be seen (by whom?)
• ... is/was noted (by whom?)
• ... is shown  (by whom?)

Passive constructions often contain a form of "to be": is, was, been, were, etc. But the way to determine if a sentence is passive is to see what part of the sentence is being acted upon. If the subject is acting ("I am reading a study"), then the sentence is active. If the object of the action is the important part of the sentence ("The study is being read by me"), then the sentence is passive. For example, a report I read today contained the sentence:

• "No discrete parenchymal mass delineated."

This is a passive construction (and an incomplete sentence).

So why do radiologists use passive forms so often?

It probably partly arises from good intentions. In medical writing, we try to remove the "I" as much as possible to achieve a (somewhat illusory) semblance of objectivity. There's probably some humility involved as well, not wishing to grandstand one's interpreting self to the reader again and again and again.

Probably the most important reason it's so pervasive is because it's unconscious. Most of us were trained that way. We absorb it by reading other reports. It's now a habit.

So why is there anything wrong with the passive voice?

The problem is that it gently tortures the English language. Sentences containing passive constructions are more grammatically complex and constant repetition of the passive tense becomes difficult for a reader to wade through. 

The passive voice also connotes a lack of confidence and adds "hedginess" to a report by artificially disassociating oneself from it.

Furthermore, some may subconsciously use this awkward construction to promote an illusion of complexity and academic erudition.

Compare these two examples:

• "a 1.8 cm para-aortic lymph node is seen" (passive)

vs.

• "there is a 1.8 cm para-aortic lymph node"

• "in the ascending colon, a fat-containing submucosal lesion is noted" (passive)

vs.

• "there is a fat-containing submucosal lesion in the ascending colon"

The first construction (the passive construction) is unnecessarily complex. Seen by whom? Even though the sentences contain the same number of words, one has to read the first sentence more slowly... the grammar is implying something, leaving behind some faint residue of mystery. The second sentence (the more active existential "There is..." construction) is simple and declarative. One can read it at top speed. There is no grammatical mystery.

There is no situation in which a passive voice is more clear and concise than an active voice.

So, active voice vs. passive voice... why should you as radiologist care?

You should care because over the remainder of your career you will probably craft thousands (or tens of thousands) of these important little text objects we call radiology reports.

If you're going to spend a good part of your life putting these things together, it's important to be conscious in your choice of voice. The active voice is easier on the reader. The active voice is often shorter, saving you valuable time over thousands of reports. The passive voice may seem nobly objective, but it's a strain on grammar and it could be abused as a subtle (and eventually habitual) way to avoid committing to the second duty of the radiologist, to medically interpret the image. 

Try experimenting with your reports by eliminating the passive voice (for instance, see the next blog post "Staying active: an exercise in reporting").  Your readers will thank you ("you will be thanked by your readers"?). You may even find that you prefer it, too.

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Thanks to Tim Luijkx and Eric A. Blair.

With the launch of Radiopaedia Courses and our (very) successful first course, we have now added the ability for all registered users to keep track of the courses they have attended and from now on print-out attendance certificates. 

Just click on your name (top right) when logged in and select "courses" 

It is certainly true that appreciating contrast enhancement of structures or lesions in the soft tissues, especially if fat is present, feels easier when the images are fat saturated. So is there a reason to perform non-fat saturated post contrast images? 

For some time as a registrar I thought the answer to that was ‘no’ (other than to save the extra time that fat saturating takes) and I have encountered many registrars / residents and consultants / attending that agree. 

Over the years I have come to appreciate the danger of fat saturating all post contrast images. The case below I think elegantly demonstrates this danger, and will hopefully change your mind. 

Figure 1

This patient had a thoracic meningioma resected some time ago, and on the most recent scan I read in addition to the post operative change a spherical structure was visible in the subcutaneous tissues (Figure 1). It is located just deep to the dermis in the subcutaneous fat, has intermediate to high signal on T2 weighted imaging and low signal on T1 weighted imaging. On post contrast fat saturated T1 images it unequivocally demonstrates vivid and homogeneous contrast enhancement. Right? 

Well the problem is it is hard to think of a solid enhancing lesion in this location, especially as it has a little tail exerting to the surface of the skin. This should be a sebaceous cyst and its appearance on T1 and T2 is perfect for this. Sebaceous cysts are just balls of keratin (indistinguishable from intracranial epidermoid cyst and temporal bone cholesteatomas), and thus should not enhance. 

Going back to earlier studies this lesion had not changed, but on every study appears to vividly enhance on fat suppressed post contrast T1 sequences. Finally I found a study from 2 years earlier (Figure 2) where neither axial nor sagittal planes where fat suppressed, and lo and behold the lesion does not enhance. Not at all. We have subsequently scanned this patient without fat suppression in one plane and again the lesion demonstrates no enhancement. 

Figure 2

The only clue to the fact that this lesion does not enhance is that it shouldn't enhance given the likely pathology. This is all well and good for an incidental benign lesion, but would be problematic if we were performing this study specifically to characterize a lump. 

Adding contrast and then fat suppressing an image dramatically changes the signal and contrast of the whole image, and one must not be tempted in comparing T1 and T1 C+ fat sat for the presence of enhancement.

You need to perform one sequence with only one changed parameter

Instead you need to perform one sequence with only one changed parameter. This can be done in two ways: 
1. post contrast perform one plane without fat saturation and the other one with fat saturation
2. pre-contrast perform one plane without fat suppression and the other with

So the take home message is this: 

It is ok to assess extent of enhancement using only fat saturated sequences, once you have established that enhancement is present. Do not try and characterize presence or absence of enhancement without an appropriate comparison pair of sequences where the only parameter changed is the presence or absence of contrast. 

Frank Gaillard

Dr Frank Gaillard is a neuroradiologist at the Royal Melbourne Hospit

We have been putting in a tremendous amount of work into improving our playlists and creating a compelling format to present radiology cases, with full stack and multi-study case support. We have not finished yet, but already this is rapidly becoming a new standard in teaching radiology. 

Slides

You can add static images between cases in your playlist. These can be anything, but ideally they are powerpoint / keynote slides exported as images (just go to "save as -> images" or "export as images" menu options in "file"). 

Then click the + where you want to add them, and drag and drop one or more images into you playlist (you need to be in edit mode to do this naturally). 

Hide case components

Sometimes you don't want to show the whole case, but just one study. Or maybe you want to hide the questions etc... Well now you can hide any (or even all) components form a study. Just click the three horizontal lines in the bottom right corner of a case thumbnail and toggle visibility. Green eye = visible. Grey eye = invisible. 

Control your presentation with keyboard arrow keys

You can now control your presentation using the keyboard arrow keys.

• Right arrow key = the orange button 
  • slides = next slide / start of next case
  • cases = next component (or next case if at the end)
• Left arrow key
  • slides = previous slide / start of previous case
  • cases = previous case; not previous component (yet)
• Up / Down arrow key
  • slides = N/A
  • cases = scroll up / down if a stack

Here's a playlist of 10 emergency radiology video tutorials that I've put together from our Radiology Channel collection. It includes topics like appendicitis, elbow joint effusion, stroke and Jefferson's fracture. It's a little taste of what to expect from our Emergency Radiology Course. You can join me at the course in Melbourne on Saturday May 16 or you can watch online for just $25. So if you love this kind of stuff and want to register for the official course then click here.