Curiosity in medical imaging often begins with a clinical question, grounded in the patient’s history, symptoms, or physical findings. It is this question that directs the observer’s attention and sets the stage for intentional engagement.
Whether subtle or obvious, curiosity draws the viewer toward the image with the goal of uncovering what might explain the clinical concern.

“Curiosity is the fuel. Everything else is the journey.”
— Ashley Davidoff, MD – The Common Vein |

The conscious decision to stop and look — to pause, focus, and commit to exploring the image with purpose.

In the context of radiology, this moment often begins with the next case appearing on screen — the familiar mental shift of “Next case…” becomes “I will give this image my full attention.”

Intentional engagement connects curiosity with discipline. It invites the viewer to consider:

• What is the history?
• What is the clinical background?
  These questions anchor the image in its context and prepare the observer to begin seeing actively

• A broad, deliberate act of looking. During observation, the questions that arise are often a blend of unconscious reactions and conscious focus.

• The initial response is typically intuitive — a fast, almost instinctive reaction based on pattern recognition. The first subconscious question might be:
  • “Is this image normal or abnormal?”

  From that starting point, the eye may take a slightly deeper dive based on the clinical context, briefly scanning areas related to the suspected issue.

  This general scan is shaped by habit and training — often unique to each observer. While still avoiding analysis, the mind begins to frame the visual field, setting the stage for structured identification

The observer now turns to consciously evaluate the visual units within the image.

In medical imaging, a unit is a distinct anatomical or pathological structure.

• In the heart, units may include individual chambers or valves.

• In the lungs, units include airways, lobes, and segments.

• In disease, a unit may be a mass, nodule, area of consolidation, or line of thickening.

In some cases, as with an obvious mass in the right upper lobe, the unit draws immediate attention and becomes the starting point for analysis.

In other cases where no abnormality stands out, the observer must actively search for units using a structured search pattern.
A routine chest X-ray (CXR) involves scanning just one or two projections. An experienced eye can evaluate a CXR with familiar units in seconds.

Units of the Lungs and heart in a Single CT Slice

A chest CT, however, may produce hundreds to thousands of images — requiring the viewer to identify a unit in one slice and follow it across multiple levels.

A well-developed search pattern becomes essential. This is a personalized, practiced method that increases visual fluency and efficiency over time.

A good search pattern is:

• Spatially logical — follows anatomical organization

• Flowing — guides the eye naturally from structure to structure

• Repeatable — encourages consistency and thoroughness

🧘‍♂️ Practice Builds Pattern Recognition
Like musicians mastering scales, radiologists master structure through repetition.
As the search pattern becomes second nature, mental energy shifts from technique to interpretation, freeing the mind to focus on insight, synthesis, and diagnosis.

Each unit is evaluated based on:

• Size
• Shape
• Position
• Character (including emotional and structural expression)
• Time (if relevant — reflecting progression or context)
• And finally, its connection or relationship to other structures within the image , its clinical context or its surrounding environment.

This method is summarized by the U SSPCT C mnemonic used in The Common Vein.

Using this approach, we assess whether the unit is clearly normal, clearly abnormal, or indeterminate. In cases of uncertainty, further imaging, comparison studies, or clinical correlation may be necessary to clarify the status.

Ultimately, the result of this analysis can be summarized graphically — as:

A unit is an identifiable structure that can be named

In this case, below there is a very obvious unit — the mass in the right upper lobe — so we begin the analysis with that distinct finding.

The size of a unit — whether measured in absolute dimensions, counted in number, or noted for its variability — carries anatomical and diagnostic significance.

In the first example above, we see innumerable micronodules, all roughly the same size, a pattern consistent with bronchiolitis.

In the second case, larger nodules with size variation suggest metastatic disease. However, in the appropriate clinical context, they could also represent infectious or inflammatory nodules.

Size is rarely meaningful on its own — it gains power when interpreted in context and alongside pattern, distribution, and clinical background.

Variations of Lung Nodules and MAsses and their relation to time

In medical imaging, positional awareness is essential — not only in relation to the anatomy, but also in relation to the expected patterns of disease distribution.
It helps refine differential diagnosis and must be interpreted within the anatomic context and clinical background.

here something is positioned in the image, may have relevance to the diagnosis.  For example  upper lung field disease often is a manifestation of TB sarcoid and other inhalational diseases

For example, an elastic band is defined as elastic because every time a diverging physical force is applied and released, it reliably returns to its original length — this repeatable behavior defines its character.

In radiology, a structure’s character is defined by how it consistently interacts with an applied energy or force whether the interrogating  force is  ultrasound X-rays, changing magnetic fields or radioisotopes.

For example a  fluid-filled cyst when interrogated by ultrasound waves, will compleytely transmit the  sound without reflection  resulting in an echo-free structure

These consistent responses allow radiologists to characterize tissue types and abnormalities — often forming the foundation of diagnosis.

T: Time

In the evaluation of a medical image, time is understood by comparing the current study with prior imaging. This comparison allows the observer to assess whether a structure has changed over time — such as demonstrating growth (as in cancer or infection), regression (as in response to therapy), or stability (suggesting benignity or chronicity). Understanding time enables us to interpret the natural history of disease, the effectiveness of treatment, or the urgency of intervention.

After individual units are analyzed, the next step is to explore their relationships — to see how the findings across units connect and associate, both anatomically and diagnostically, and within the broader clinical context.

Understanding these connections helps form a coherent narrative from seemingly isolated findings.

Example:
In the CT scan shown above, there is a mediastinal mass (ringed in red) — representing one unit. In the lower image, the liver shows multiple nodules (red arrowheads) — additional units.
On their own, each could raise a range of possibilities.
But together, the connection between these findings strongly suggests metastatic disease, with the mediastinal mass likely representing a primary lung malignancy and the liver nodules indicating secondary spread.

The value of connecting units lies in seeing the whole picture — transforming fragmented findings into a unified diagnostic impression.

The Penny Drops

In this final phase, the entire image begins to reveal its meaning or diagnosis, integrating everything that has come before — from observation and unit analysis to the recognition of connections.

The Penny Drops

Comprehension and interpretation are multi-layered processes. They depend on a range of individual factors, including:

• A solid knowledge base (built through education)

• The observer’s interest level

• Memory (the ability to recall visual and diagnostic patterns)

• Experience in recognizing variations of normal and abnormal

• And often, an element of clinical intuition or talent

In some cases, everything aligns — the anatomy, the pattern, the history — and the diagnosis becomes immediately clear and unmistakable.

The proverbial “penny drops”, and the findings are pathognomonic — leaving little doubt about what is being seen.

But in many cases, interpretation is not so straightforward. The image presents possibilities, not certainties. The observer must weigh findings in context, consider a differential diagnosis, and formulate a working impression.

The conclusion may be confident — or it may be cautious, accompanied by a recommendation for how to further investigate or clarify:

• Additional imaging

• Clinical correlation

• Follow-up studies or biopsy

Ultimately, comprehension is the act of assembling meaning — the final synthesis of curiosity, observation, analysis, pattern recognition, and judgment.