BIRADS 4a, 4b, 4c

djmammo

I see many questions and concerns related to these subcategories. As many of you are aware they are not yet required and the reasons are contained in this lengthy article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4463260/ .

We rads are not given specific guidelines in the use of the a,b, and c subgroups other than "low, medium and high". Any associated quantification in the form of a percentage would have been determined retrospectively from compiled yearly MQSA Audits of radiologists reading breast imaging AND who are using the subclassifications.

As yet there are no charts that equate particular imaging attributes to specific risk numbers other than low, medium and high. Take into account that each finding has several attributes that each modify the risk of the other. The bottom line is the subcategory is directly related to each individual rad's opinion of the overall appearance of the lesion (with the patient history/risk factors often used as a tiebreaker) and this will directly vary with the breast imaging experience of the rad which is widely variable especially if the rad is not reading 100% breast imaging, 100% of the time. Those that only read breast are in a very small minority nationwide (USA).

Here is the conclusion of the study cited above:

"In conclusion, subcategorizing BI-RADS 4 lesions is useful in determining the risk of malignancy, but no definitive diagnostic criteria could be established for subcategorization. BI-RADS 4 subcategorization is based solely on the radiologist's level of suspicion of malignancy. This is highly dependent on the experience of a radiologist. Moreover, subcategorization is more difficult for smaller lesions. Thus, objective and clear subclassification rules are needed."

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This next part is just my opinion:

The B4 category is used when a biopsy is recommended. Once that is scheduled an answer to the clinical question "cancer/no cancer?" will be answered within a week or two. There is no added clinical benefit to the assignment to a subgroup except to modify the patient's expectations in the interval between the recommendation for biopsy and the issuance of the path report. The difference between B4c and B5 is that we would be surprised if a B5 lesion came back benign.

Not that I believe any Birads subgroups are necessary, if I were assigned the task of constructing a set of subcategories it would be attached to the B3 reports (Short Term Follow-up Recommended) not B4. Instead of indicating how sure I am something is malignant, they would reflect how sure I was that something was benign which would influence whether or not a patient would choose to wait 6 mos for a follow up or opt for a biopsy instead, choices that would have a more significant clinical impact on the patient.

(all edits for grammar and clarification)

robinorbit

This is very helpful, thank you. I keep getting caught up in the subcategories and forgetting those are still just educated guesses.