Role of high-resolution pinhole tomography in the evaluation of thyroid abnormalities.

The present study was undertaken to evaluate the contribution of pinhole-single photon emission computed tomography (P-SPECT) to scintigraphy of the thyroid gland. Thirty-six patients, referred for thyroid scintigraphy because of palpatory or ultrasonographic findings, were studied after intravenous administration of technetium-99m pertechnetate (222 MBq) using a rectilinear scanner and a single-headed rotating gamma camera equipped with a pinhole collimator. P-SPECT study was acquired on a 128 x 128 matrix, in 30 projections over 180 degrees and an acquisition time of 40 seconds per step. After transaxial reconstruction, coronal slices were compared with planar views obtained by the scanner. The size of the thyroid gland obtained by P-SPECT matched the life-size image of a rectilinear scan, and it clearly delineated the shape and borders of two huge multinodular glands. Its major contribution was in its improved resolution. Pinhole-SPECT identified 21 foci not visualized on planar views, 19 cold lesions, and 2 "warm" nodules embedded in normal tissue of 13 patients. Furthermore, it clearly delineated 18 discrete ill-defined nodules of 13 patients, (single in 4 patients and multiple in 9 patients): 16 cold lesions, and 2 hot foci. When a distinct palpable nodule was present, whether cold (22 lesions) or hot (2 foci), SPECT was of no additional diagnostic value. However, when the palpable nodule was a toxic one, the contralateral suppressed lobe was visible on SPECT only. Two ultrasonographic findings, of 3- and 5-mm in diameter, were neither identified on planar views nor on P-SPECT. In conclusion, P-SPECT of the thyroid gland improves delineation of huge multinodular glands and detection of small nodules (within the resolution of the camera) that could otherwise have been overlooked on planar views of a thyroid scanner. It allows for definition of tracer uptake in tiny discrete nodules and in multinodular goiter, and is a better guide to the physician in fine-needle aspiration of the cold areas.

Liquid chromatographic determination of flunarizine dihydrochloride in the presence of its degradation product.

A simple, stability-indicating liquid chromatographic method has been developed for the assay of flunarizine dihydrochloride in the presence of its acid-induced degradation product. A Bondapak-C18 column was used with a mobile phase consisting of methanol-water (75:25, v/v) containing 0.5% w/v sodium chloride and 0.2% v/v triethanolamine adjusted to pH 6.6 with 30% hydrochloric acid at a flow rate 2 ml min-1. Quantitation was achieved with UV detection at 254 nm based on peak area or peak height ratios. The proposed method was successfully applied to the determination of the drug in laboratory-prepared mixtures in the presence of its degradation product and in capsules. Moreover, the method was utilized to investigate the kinetics of the degradation process at different temperatures and the apparent first-order rate constant, half-life and activation energy calculated.