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  • Writer's pictureDr Sally Ayesa

The Goldilocks Zone

When the information presented is not to brief and not too detailed, but just right. This is "The Goldilocks Zone" a turn of phrase I find myself using a lot when running cases with candidates. Provided you are reading the case in front of you correctly, considering the concept of the Goldilocks zone in your technique will help you sound more polished and professional.

This list of differential diagnoses is just right ...

Describing findings

Mentors of mine have shared that they can get frustrated by viva candidates who over-describe findings (often those that are of little consequence to the final diagnosis). An example may be a breast case where there is a large, irregular mass on ultrasound (with all the features of a breast cancer), and the candidate spends thirty seconds or more describing the incidental simple cyst. As a soon to be radiologist, you should be well qualified to either call it a simple cyst point blank or offer a brief one sentence assessment (e.g. there is an ovoid subcentimetre, anechoic structure at 12 o'clock 2cm from the nipple in keeping with a simple cyst). I could be a fairly verbose presenter and usually stuck with the latter as part of my technique.

Of course, it can be hard to know if you are over-describing a finding if you are in the hot seat and the pressure is on.

When preparing for my neuroradiology viva, I would find myself tied in knots trying to describe all of the structures of the brain which were involved in a pattern of oedema. One day my (amazing) consultant just looked at me and said - "I don't think spending this much time assessing the pattern of oedema is helping your presentation. Just mention it, consider the mass effect and move on." In short - don't get lost in the minutiae of a case.

I think a good rule of thumb is to describe enough until you feel that you can justify your preferred differential diagnosis. For a brain tumour, this may involve assessment of the location, T1, T2, DWI and SWI characteristics, enhancement pattern, mass effect and oedema - synthesizing the findings as you go. It would also be worthwhile commenting on whether the abnormality is solitary of multifocal, as well as assessment of causes and complications based on your preferred differential.

Here is an example: "There is a heterogenous, enhancing mass centred on the corpus collosum, extending into both frontal lobes. There is evidence of diffusion restriction and intra-lesional haemorrhage. There is moderate surrounding oedema and mild mass effect on the frontal horns of the lateral ventricles. The lesion appears solitary. Imaging features are consistent with a glioblastoma, particularly a butterfly glioma. This diagnosis would warrant discussion with the referring clinician and I would recommend urgent neurosurgical review."

"Earning" extra views

In the chest viva, often the lateral view is not provided in the first instance - leading the candidate to feel that they have to earn it through thorough description and rationalisation. In my experience, this is partly true - but sometimes we get caught in a loop of over justification.

Ideally, you want to demonstrate that you can work out the case to a point and can use sensible reasoning to localise the abnormality. In practice, however, you will usually find a pulmonary nodule and immediately bring up the lateral so you can assess it on both views at once. In my opinion, I feel that a few sentences of (relevant) description and suggesting a sensible reason for wanting to review the lateral is what you should aim for. Saying "I would routinely review a lateral" without offering a justification is not generally advisable.

For example, in a solitary pulmonary nodule case "There is a well circumscribed rounded opacity projected in the right mid zone. I do not appreciate calcification, cavitation or rib destruction, and the lesion appears solitary. I would review a lateral projection to confirm the location of the lesion, which is possibly within the anterior right upper lobe or apical left lower lobe..." At this point it is worthwhile pausing briefly to see if the lateral view comes up. Continue on if it doesn't.

Forming lists of differential diagnoses

In the lead up to the viva exam, there can be a period (or periods) of dyssynchrony between the volume of knowledge you hold and your ability to read a live case. All of your dedicated textbook, casebook and article reading has left you with a wealth of knowledge and extensive differential lists for a wide range of imaging findings. Armed with this knowledge, it can be all too easy to turn a straightforward case into a shopping list of differential diagnoses.

While you may feel that this is an excellent opportunity to demonstrate your knowledge about a topic, it usually has the opposite effect. The examiner may interpret your long list of unfiltered differential diagnoses as a lack of synthesis. In most cases, there will be clues available from the clinical history, age and gender of the patient, characteristics of the primary lesion and associated findings. These usually allow you to narrow down the differential list.

In an anterior mediastinal mass case, it is very tempting to throw out the 'five Ts' straight out of the gate. Your presentation will be enhanced, however, if you tailor the order based on the demographics of the patient in front of you and morphology of the mass. For a lobulated mass in a 20 year old patient, the underlying pathology is more likely to be lymphoma (or a germ cell tumour), rather than a thymoma (which is more common in patients over the age of 40).

Concluding the case

I have worked with some candidates who use their conclusion to provide as much information about their favoured diagnosis as they can, in the hope of demonstrating their depth of knowledge. A little knowledge is good, but in excess it adds little to your overall mark and can waste time - especially if you have to search the back of your brain for the fact.

I feel that there is more to be gained by demonstrating your knowledge of your preferred diagnosis in your search pattern (i.e. vocalising that you are looking for specific associated findings or complications, then expressing the relevant negatives), and management recommendations.

Show that you understand the emergent nature of an aortic transection by immediately calling the emergency team and recommending urgent cardiothoracic surgery review.

Show that you understand the public health concerns regarding patients with suspected or confirmed tuberculosis by raising the issue of contact precautions.

Show that you understand the multisystem manifestations of Von Hippel Lindau Syndrome by recommending an MRI of the brain after you have described the on the CT abdomen.

Hopefully, by putting your best foot forward you can show your examiners that you deserve to walk out of the viva exam a radiologist.

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