Background and Aim: Non-invasive imaging techniques such as 99mTc-
Sestamibi (MIBI) thyroid scanning and US Elastography are widely utilized in
the evaluation of thyroid nodule. However, the outcomes of these diagnostic
tests are inconsistent; the goal of our study was to compare the accuracy of US
Elastography and 99mTc-MIBI in distinguishing between malignant and benign
thyroid nodules in patients with a cytological diagnosis of follicular neoplasm.
Patients and Methods: Twenty-one patients with thyroid nodules underwent
US-elastography by an experienced radiologist to obtain the Elastography score
(ES) and the strain ratio (SR). 99mTc-Pertechnetate scintigraphy and dual phase
MIBI SPECT/CT scanning were also done. Tracer uptake in MIBI images were
visually graded as; no, faint, iso-, and intense uptake. Additionally, the pattern
of tracer washout—decreased, unchanged, or increased uptake in the delayed
images as compared to the early images was used. As the gold standard,
radiologic follow-up and histopathology were utilized.
Results: The majority of nodules (16/21) were TI-RADS IV, while the
remaining five were TI-RADS III. Elastography showed that the majority of
benign nodules (87.5%, 14/16 patients) had a score of 3, with one nodule in
each category for score 2 and score 4, while malignant nodules had two with a
score of 3, two with a score 4, and one with a score 5, yielding 60% sensitivity,
93.8% specificity, and 85.7% accuracy (P=0.008).The mean SR value for the
benign nodules was insignificantly lower than that of the malignant ones
(3.1±1.9 versus 4.5±3.2, P= 0.236). With an AUC of 0.619 (95%- CI: 0.294-
0.944 and P=.433), the optimal SR cutoff value for detecting malignancy was
set at 0.82, yielding 100% sensitivity and 93.8% specificity. The number of
malignant and benign nodules was found to be 5 and 16, respectively. Most
nodules were hypo-functioning in nature. With a 100 % NPV, delayed MIBI
image scoring outperformed the early one. Despite having the same sensitivity
(80%), the washout pattern in delayed SPECT/CT scans had a significantly
higher specificity, accuracy, NPV, and PPV (P=0.003) than that in the delayed
planar ones (P=0.003).
Conclusion: In cases of thyroid nodules with a cytological diagnosis of
follicular neoplasm; SR yields considerably higher sensitivity and specificity
than the Elastography score. Additionally, the use of SPECT/CT strengthens the
diagnostic accuracy of the late MIBI scans. The results of MIBI readings proved
superior to those of Elastography scores.