MRI versus ¹³¹I whole-body scintigraphy for the detection of lymph node recurrences in differentiated thyroid carcinoma.
OBJECTIVE
The aim of this study was to compare the clinical usefulness of MRI and radioiodine (¹³¹I) whole-body scintigraphy for the detection of lymph node metastases in differentiated thyroid carcinoma (DTC).


METHODS
After surgery and ¹³¹I therapy, 40 patients with DTC underwent ¹³¹I whole-body scintigraphy and MRI. Each patient was clinically suspected of having or already had evidence of nodal recurrences (confirmed by laboratory studies, cytologic analysis, or whole-body scintigraphy). Planar whole-body scintigraphy was done after administration of 111 MBq of ¹³¹I, and MRI was done using spin-echo T1- and T2-weighted imaging, T1-weighted spin-echo imaging with fat suppression, and STIR sequences.


RESULTS
MRI detected nodal metastases as partly or entirely cystic and as heterogeneously enhanced on contrast-enhanced T1-weighted images. Hyperintense cystic areas appeared on T1- and T2-weighted images and STIR sequences in 57% of cases. Nodal metastases showed extracapsular spread in 24% of patients. MRI results were true-positive in 76%, true-negative in 90%, false-negative in 24%, and false-positive in 11% of cases, whereas ¹³¹I whole-body scintigraphy results were true-positive in 71%, true-negative in 91%, and false-negative in 29% of cases. There were no false-positive results of ¹³¹I whole-body scintigraphy. False-negative whole-body scintigraphy was induced by tumor dedifferentiation. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MRI were 76.2%, 89.5%, 82.5%, 88.9%, and 77.3%, respectively, and the corresponding values for ¹³¹I whole-body scintigraphy were 71.4%, 100%, 85%, 100%, and 76%, respectively.


CONCLUSIONS
Whole-body scintigraphy is more specific than MRI in the detection of nodal metastases in patients with DTC. The principal value of MRI is in non-iodine-avid recurrences and in evaluation of mediastinal foci.
Mihailovic
Jasna
J
Department of Nuclear Medicine, Oncology Institute of Vojvodina, Sremska Kamenica, Serbia. jasnans@eunet.rs
Prvulovic
Mladen
M
Ivkovic
Miodrag
M
Markoski
Branko
B
Martinov
Dobrivoje
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003131:Combined Modality Therapy; D003287:Contrast Media; D005260:Female; D015902:Gamma Cameras; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D013965:Thyroidectomy; D016896:Treatment Outcome; D051598:Whole Body Imaging
D003287:Contrast Media; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals