A cell phone lost, gone since when? Last used earlier in the morning….
Where had it gone? My husband, a farsighted intelligent man looked and looked everywhere he had been and anywhere it might have fallen. Unhappy about the loss, he was determined to look long and hard in an attempt to recover it. He believes I have x-ray vision, and sure that it would work its usual magic, he entreated me to look with him. I, more skeptical, thought it a waste of time. Reluctantly I relented, and followed in his footsteps to try and find it. I am short sighted and even with glasses can’t see very well in the distance. Yet I am a trained radiologist and one with years of reading cases. He was sure that my systematic approach to looking for radiographic findings would allow me to find what he had not.
We scoured the grocery store parking lot, asked at customer service and did all the things one should do to try and retrieve a hopelessly lost phone. The next stop was the post office lot, which closed on a Sunday and thus empty. I scanned the lot, looking for a black phone, on black asphalt. A flat black rectangle, hard to see, and only possibly there…. I deliberately looked across the parking lot in the fashion I would use to systematically look for a finding on a case—first a glace across the ground, then deliberate looking back and forth up and down to capture the abnormality, however subtle and distinguish it from the background noise.
Much as one looks for the 2mm nodule at a lung base, described on the last report, but not immediately seen, I scanned the asphalt. Looking for black phone on the parking lot, scanning back and forth. No phone. Almost defeated, I said –where did you park, where did you stand: retrace your steps. I began the search on the road itself, a last ditch effort. Cars passing by at some speed and there, on the road, black upon black was the outline of a small rectangular object, distinguished by a shiny exterior, a different texture, a subtle finding indeed, hidden in plain view. Smashed beyond usefulness into the pavement, was the missing phone.
How does one search for a finding– almost imperceptible, yet there, real and once seen, obvious. There have been many studies to look at a Radiologist’s eye motions, not predictable, not easily characterized. Yet the mature Radiologist has been shown for some time to look differently at an image than a novice.[i] I believe we do look at images differently when we have experience, and can often recognize important abnormalities at a glance, yet I feel that we must also systematically target our search to overcome perception bias. We must see it all, but perceive and recognize the key the key findings—ALL of them! We all know about the ”Instant Happiness Syndrome” where when we find the obvious abnormality, we stop looking for more… Yet when one looks for this in Google Scholar there is inly one reference cited[ii]. We don’t have all that much insight into how we perceive images, despite looking at thousands a day.
Understanding how radiologists detect and interpret images is complex and key to training new Radiologists, improving our own performance, and to learn how to best integrating computer aided diagnosis into our diagnostic armamentarium. Given a case with thousands of images, we cannot look carefully at every pixel, yet we are tasked with finding every significant finding. How can we do this if we can’t even find the Gorilla in the picture?[iii] How do we actually do it?
That seems to depend on depends on our level of training, experience and subject matter expertise. Thinking about how we recognize an ”Aunt Minnie” or how we “Gestalt” a case is fascinating, and indeed a real phenomenon! “Gestalt Theory: Implications for Radiology Education” by Koontz and Gunderman i[iv]s a thought provoking must-read for all of us! Their integration of Art, Radiology, Gestalt Theory and our lives as physicians begins to explain how we “see.” Examples of how and why we perceive images, suggest such features as the similarity and proximity of objects change our perception of the relationship of one to the other, and make some things easier to see than others. He suggests that this explains why it is harder to see pulmonary nodules in the lung fields because we are distracted by the heart shadow—bright and bold in the center. On some level, I think we know this, almost instinctively, after years of plying our profession.
How do I look at a case? I think I “gestalt” it, and then go back, and do a targeted search, looking carefully for findings I am expecting to see. That is where the old reports are crucial—if someone saw something the last time, I will make sure to look especially hard to see it again. The history is key! If I know the patient has right lower quadrant pain, fever and an elevated white count, I will certainly make sure the appendix is normal! And then I will look again, just to be sure!
Does experience help? It seems so! It seems that novice Radiologists eyes search haphazardly for findings, while more experienced Radiologists exhibit more concise eye movements, finding pertinent abnormalities faster[v]. Yet it has been demonstrated that, as a profession, we are no better than others at finding WALDO.[vi] I can’t argue with science—but I like to think we would be more skilled…
It seems that despite our ability to perceive abnormalities in a flash on cases, and to find more abnormalities than non-Radiologists, we still don’t really know why. We don’t know how we do it, nor why we make mistakes. Distractions, poor working conditions, poor technique, fatigue, lack of training, lack of knowledge may be invoked[vii][viii]; yet errors in perception are real, and not well understood as well. How can we teach our Residents that which we do not ourselves understand? How can we perform better, if we don’t understand our process? How can we make sure we always see the gorilla in the CT?
Do you think we have x-ray vision? Or was I just lucky to find that cell phone?