Technetium-99m methoxyisobutylisonitrile scintigraphy in the
assessment of cold thyroid nodules: is it time to change
the approach to the management of cold thyroid nodules?
methoxyisobutylisonitrile (99mTc-MIBI) is recommended for
evaluating thyroid nodule metabolism. In addition, it may
help differentiate between benign and malignant nodules;
however, the efficacy of this technique has not been fully
elucidated. Therefore, it is not currently performed for
routine clinical application. This prospective study was
conducted to investigate the clinical significance
of 99mTc-MIBI scintigraphy in the assessment of patients
with cold thyroid nodules.
Patients and methods This prospective study was
conducted on 104 patients with cold thyroid nodules
greater than 1 cm in diameter as detected on
99mTc-pertechnetate scintigraphy. Uptake of MIBI in thyroid
nodules was compared with that in the surrounding normal
thyroid tissue for both early and delayed images, and a score
of 0–3 was assigned to each nodule as follows: 0, cold; 1,
decreased; 2, equal; 3, increased. The thyroid scan was
performed 20 and 40min after intravenous injection of
555MBq of 99mTc-MIBI. The patients underwent fine-needle
aspiration cytology (FNAC). Detailed statistical parameters
were determined on a per-nodule basis for each qualitative
and quantitative scan analysis, as defined by histology.
Results A total of 104 patients (93 women and 11 men;
mean age 40.76±11.40 years, range 20–73) with a total
number of 167 cold nodules were included in this study.
When 99mTc-MIBI uptake was regarded as the criterion
of malignancy in 99mTc-MIBI scintigraphy, the accuracy
was between 69.46 and 92.21% on using seven different
methods. In addition, FNAC findings indicated a sensitivity
of 66.66%, a specificity of 100%, a negative predictive value
of 95.72%, a positive predictive value of 100%, and an
accuracy of 96.06%. Six malignant cold nodules were
detected on a positive 99mTc-MIBI scan, which were
determined as benign nodules on FNAC examinations.
Conclusion The study demonstrated that 99mTc-MIBI
scanning can be complementary to other diagnostic
techniques in patients with cold thyroid nodules. In
addition, because of its availability, rather low cost,
simple protocol, and objective semiquantitative
information, 99mTc-MIBI scanning seems to hold promise
in routine imaging of cold thyroid nodules. Nucl Med
Commun 35:51–57 �c 2013 Wolters Kluwer Health |
Lippincott Williams & Wilkins
