Clinical significance of thyroid visualization on technegas ventilation scintigraphy.
BACKGROUND
We investigated the clinical significance of thyroid visualization on technegas (TcG) ventilation scintigraphy (TcGS) based on the hypothesis that this visualization may be correlated with thyroid disease with high radioactive thyroid uptake (RATU).


METHODS
From a total of 1022 consecutive patients undergoing TcG/99mTc macroaggregated albumin ventilation/perfusion (V/Q) scintigraphy to exclude pulmonary embolism, 114 who underwent in vitro thyroid function tests (TFTs) within 2 weeks of the lung scintigraphy were included in the retrospective study. In addition, in 10 patients in whom high RATU was noted on [99mTc]pertechnetate thyroid scintigraphy, TcGS was performed prospectively. The degree of thyroid activity in each patient was graded on a scale of 0 to 2 (grade 0 = no or faint uptake; grade 1 = mild uptake, but less than the lung; and grade 2 = strong uptake, similar to, or more than, the lung).


RESULTS
Thyroid uptake was observed on TcGS in 17.5% of the patient group (20/114; 10 with grade 1, 10 with grade 2). Serum T3, T4 and TSH values differed significantly, depending on the grade of thyroid activity. All patients showing grade 2 thyroid uptake were clinically diagnosed as having Graves' disease. None of the 94 patients with grade 0 on TcGS had evidence of hyperthyroidism, although four patients had hypothyroidism. In the prospective group, all patients showed any visualization of the thyroid on TcGS (3 with grade 1, 7 with grade 2). The final diagnoses for these patients were Graves' disease in six, Hashimoto's thyroiditis in three and post-partum thyroiditis in one.


CONCLUSIONS
Thyroid visualization during TcGS appears to be correlated with thyroid disease with high RATU. Such a finding may also deserve further evaluation for additional irregularities in thyroid function.
Choi
Joon Young
JY
Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Kangnam-ku, Seoul, Korea.
Jang
Hong-Ju
HJ
Park
Jung Mi
JM
Lee
Kyung-Han
KH
Choi
Yong
Y
Choe
Yearn Seong
YS
Kim
Byung-Tae
BT
D000280:Administration, Inhalation; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000150:complications / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013670:Sodium Pertechnetate Tc 99m / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013959:Thyroid Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism*; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000378:metabolism*; D014692:Ventilation-Perfusion Ratio
D019275:Radiopharmaceuticals; C056708:Technegas; D013670:Sodium Pertechnetate Tc 99m