Abnormal 99mTc-MIBI Uptakein left lung mimicking a neoplastic lesion in a young woman with nodular goiter. A rare pitfall of 99mTc-MIBI

Abstract

^99mTc-MIBI scintigraphy is a useful diagnostic tool in patients affected by thyroid disease, as already described. We report on a young female patient with a thyroid nodule that largely occupied the right lobe. The nodule showed suspicious findings at thyroid ultrasound thus fine needle ago-cytology was performed. The result was conclusive for a class III nodule (i.e. indeterminate lesion), according to Bethesda system. Laboratory evaluations demonstrated an euthyroidsm state but serum TSH level was in the lower part of normal range. The patient underwent thyroid scintigraphy performed using both  ^99mTc-pertechnetate and ^99mTc-MIBI.  The nodule was “cold” at ^99mTc-pertechnetate but showed  increased MIBI uptake  (^99mTc-MIBI >^99mTc-pert.) at qualitative analysis. However, quantitative evaluation according to Wash-out index method was consistent with a benign lesion. At MIBI-scintigraphy a well defined and intense tracer uptake was noted into left thorax suspected  to be a focal lung lesion. Targeted Computed Tomography did not show any lung lesion. However, the patient referred on an important car accident occurred six months before in which she have reported a severe contusive left lung trauma. At the time of car accident, a Computed Tomography study had shown an irregular opacification in the lingular division, caused by left chest contusion. Presently, the patient is regularly followed for her thyroid disease and, mainly, no evidence of lung disease is noted. The present case confirms the usefulness of ^99m Tc-MIBI in the work-up of cold thyroid nodules but highlights as an important contusive lung trauma should be taken into account as potential pitfall at ^99mTc-MIBI scintigraphy. Morpho-functional imaging can improve the diagnostic performance of functional imaging alone.