4.3 Clinical applicability
The exact time point that a recurrent nodule becomes large enough to be
radiologically traceable is unknown. Therefore, it seems unlikely that a
recurrence that manifests clinically 15 years post surgery, will have a
radiologically detectable signal in the first 6 years. The role of post
surgery MRI is well defined in clinically manifest recurrences: better
delineation and extent of recurrent nodules, their location and size as
well the size of the remaining parotid gland provides important
information for surgical planning3. However, a single
MRI to detect an occult RPA at 6 years post CD does not provide any
clinical benefit. The rarity of the event and the cost of annual
scanning for 10-20 years may not justify the potential but unproven
benefit of early recurrence detection. On the other hand, recurrences
after encapsulation tend to occur soon after the operation so there may
be a potential for close radiologic surveillance in these cases.
Re-recurrences after resection of RPAs are common. Rooker et al have
noted that if a re-recurrence does not occur within 10 years after the
second operation, it is unlikely to develop later10.
Therefore a re-recurrence within the first 5 years of surgery requires
close follow up which could justify annual imaging.