Magnetic resonance imaging for volume estimation of large multinodular goitres: a comparison with scintigraphy.

As a result of increasing interest in non-surgical treatment for the reduction of goitre size the use of magnetic resonance (MR) imaging for volume estimation of large multinodular goitres was evaluated in 20 patients (three males and 17 females; age 61 +/- 21 years) with a multinodular goitre larger than 100 ml. In addition, MR measurements were compared with scintigraphic (SC) volume estimations. Intraobserver coefficient of variation (CV) of MR measurements was 2.2 +/- 2.0% (Observer 1) and interobserver CV 4.1 +/- 2.2% (Observers 1 and 2). In all 20 patients signs of mechanical complications were shown on MR images. For SC measurements intraobserver CV was 7.5 +/- 5.7% (Observer 3) and 5.4 +/- 5.1% (Observer 4). Interobserver CV was 10.1 +/- 6.1%. The correlation between measurements with both methods was not strong (r = 0.665) and the resulting CV was 17.3 +/- 14.2%. Underestimation of SC volumes could not be explained by the presence of cysts on the surface of the thyroid. It is concluded that MR imaging can be used for in vivo thyroid volume estimation in large multinodular goitres. The high precision of MR measurements makes this technique potentially useful for the evaluation of thyroid growth and non-surgical treatment for reducing goitre size. Scintigraphic volume measurements do not suffice for this purpose. An additional advantage of MR imaging is the detailed anatomical information it provides with regard to mechanical complications of large goitres.