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RD4.1-3 | Interdisciplinary Imaging Communication — PBL Case

CLINICAL SETTING

Mrs L is a 63-year-old woman seen in a busy primary-care clinic. Over the past six weeks she has had progressively worsening pain and stiffness in her right knee, worse on rising from a chair and after walking, eased by rest. There is no redness, no fever, and no recent trauma. She is overweight and has type 2 diabetes. Two days ago she developed a separate, new symptom: a swollen, tender, warm left calf that came on after a long bus journey. She is anxious and asks her GP, 'Do I need a scan? My neighbour had a clot and was rushed to hospital.' The clinic has access to plain radiography the same day and to an ultrasound department that can usually accommodate urgent vascular requests. This case asks you to reason from clinical picture, through anatomy and pathophysiology, to the right imaging — and to communicate effectively with the radiology service for two very different problems in the same patient.

Trigger 1: The right knee — chronic mechanical pain

Focusing first on the right knee: the pain is mechanical (worse with use, eased by rest), chronic, and without inflammatory features. On examination there is bony swelling, crepitus on movement and a mild reduction in range of motion. The GP is considering a plain weight-bearing radiograph.

DISCUSSION POINTS

  • What is the most likely diagnosis for the knee, and which features point to it rather than to an inflammatory arthritis?
  • Using anatomy and pathophysiology, predict what the weight-bearing X-ray will show and explain WHY each sign occurs.
  • Why is a weight-bearing view preferred over a non-weight-bearing one for this question?
  • Draft the specific clinical question you would put on the radiograph requisition.
Click to reveal Trigger 2: The left calf — a new acute problem (discuss previous trigger first!)

Trigger 2: The left calf — a new acute problem

Now turning to the acute left calf: it is swollen, warm and tender, with a recent period of immobility (the bus journey) and risk factors of obesity and diabetes. The GP is worried about deep vein thrombosis and must decide on imaging and urgency. The patient is haemodynamically stable and ambulatory but distressed.

DISCUSSION POINTS

  • Which imaging modality is first-line for suspected DVT, and why is it preferred over X-ray or CT here?
  • Describe the key diagnostic finding on compression ultrasonography and explain its pathophysiological basis.
  • How would you convey clinical urgency on this requisition WITHOUT over-flagging it, and what relevant history and safety flags would you include?
  • How does the appropriate urgency tier for the calf differ from that for the chronic knee, and why does accurate tiering matter to the radiology department?
Click to reveal Trigger 3: Closing the loop and the interdisciplinary interface (discuss previous trigger first!)

Trigger 3: Closing the loop and the interdisciplinary interface

The radiographs and the leg ultrasound are completed. The knee film confirms moderate osteoarthritis; the leg ultrasound shows a non-compressible femoral vein consistent with acute DVT. The GP must now act on both results, communicate with the patient, and ensure the right onward steps — while reflecting on what made the communication with radiology effective.

DISCUSSION POINTS

  • The knee film is reported as 'moderate-to-severe OA' but the patient's pain is only moderate. Applying clinico-radiological correlation, how should this discordance guide management?
  • What does 'closing the loop' mean after an imaging request, and what could go wrong if it is not done for the DVT result?
  • Reflect: across both problems, what made the requisitions effective clinical communications rather than clerical forms?

Group Task Assignments

  • Group A: Build a side-by-side correlation table for the two conditions in this case — for OA and for DVT, list the relevant anatomy, the pathophysiology, the chosen modality, and the expected imaging sign. Present how each sign maps back to its mechanism.
  • Group B: Write two model requisitions for this patient (one for the knee X-ray, one for the leg ultrasound), each with a specific clinical question, relevant history, safety flags and a justified urgency tier. Be ready to defend why the urgency tiers differ.
  • Group C: Role-play the GP–radiologist phone call for the suspected DVT, then debrief on how clinical urgency was conveyed, how appropriateness was clarified, and how the communication loop was closed after the report.

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [RD4.3] What are the anatomical, pathophysiological and radiographic features of osteoarthritis, and why do radiographic severity and symptom severity correlate poorly?
  2. [RD4.3] What is the first-line modality and the hallmark diagnostic sign for deep vein thrombosis, and what is the pathophysiological basis of loss of compressibility?
  3. [RD4.1] What are the components of a high-quality imaging requisition, and how should clinical urgency be tiered and conveyed without over-flagging?
  4. [RD4.1] When and how should a primary-care physician clarify the appropriateness of an imaging investigation with the radiologist, and what does 'closing the loop' after a report involve?