Technetium-99m methoxyisobutylisonitrile imaging in the follow-up of differentiated thyroid carcinoma.
OBJECTIVE
To evaluate the potential of technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) imaging as an alternative to I-131 total-body scan (I-131 TBS) for the follow-up of patients with differentiated thyroid carcinoma (DTC).


METHODS
We performed 87 Tc-99m MIBI imaging studies in 76 DTC patients who had total or near-total thyroidectomy followed by a radioactive iodine ablation while receiving thyroxine therapy. The final diagnosis was correlated with I-131 TBS, serum thyroglobulin (Tg), other conventional imaging modalities, clinical outcome, and/or pathological report.


RESULTS
Seventy-six recurrent tumours or metastatic conditions in 58 DTC patients were detected. The overall findings of Tc-99m MIBI showed 72% sensitivity, 100% specificity and 77% accuracy. The figures for I-131 scan were 57%, 100% and 66%, respectively. When classifying upon tumour locations, Tc-99m MIBI imaging had sensitivity of 79% for cervical, 50% for mediastinal, 65% for skeletal and 69% for pulmonary metastases and the corresponding values for I-131 TBS were 33%, 67%, 94% and 75%, respectively. Furthermore, Tc-99m MIBI could detect only 44% of thyroid remnants demonstrated by radioiodine scan.


CONCLUSIONS
Tc-99m MIBI imaging is more sensitive than I-131 TBS in detecting tumours in the neck but less sensitive for metastasis elsewhere, as well as thyroid remnants. Therefore, Tc-99m MIBI imaging should not substitute but rather complement I-131 TBS for evaluation of DTC patients post-radioiodine ablation.
Sriprapaporn
J
J
Division of Nuclear Medicine, Department of Radiology, Faculty of Medicine, Siriraj Hospital, Bangkok, Thailand, 10700. sijmh@mahidol.ac.th
Toopmongkol
C
C
Satayaban
B
B
Chantamoon
N
N
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000601:surgery; D018265:Carcinoma, Papillary, Follicular / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D013965:Thyroidectomy
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi