Sialadenitis is a well-recognized adverse effect of high-dose radioactive iodine treatment. This study was undertaken to determine whether Tc-99m pertechnetate salivary gland scintigraphy may be used for objective assessment of salivary gland function in patients with thyroid cancer treated with I-131. The study group consisted of 71 patients (16 men, 55 women) with a mean age of 44 years (range, 16 to 73 years). Twenty-six (37%) patients were not given any radioiodine, and 18, 16, and 11 patients received doses of 100, 150, or 200 mCi (or higher), respectively. Parotid and submandibular glands were evaluated based on a four-grade scoring system. Correlation between the type of surgery, administered dose, time since therapy, subjective symptoms, and findings of salivary gland scintigraphy were evaluated. Subjective symptoms were questioned in 39 of the 45 patients who received radioactive iodine treatment. Fifty-four percent (21 of 39) of the patients reported xerostomia, of whom 86% (18 of 21) showed salivary gland dysfunction. Objective salivary gland dysfunction was observed in 69% (31 of 45) of patients. In 81% of the patients, the parotid glands were affected; in 13% of the patients, the submandibular glands were affected; and in 6%, both were affected (P < 0.000001). The frequency of salivary gland dysfunction showed a dose dependence to cumulative activity (P = 0.007). A greater complication rate was observed in patients with total thyroidectomy compared with subtotal surgery, although the correlation was not significant (P = 0.625). Parenchymal damage to the salivary glands induced by radioactive iodine treatment can be evaluated by salivary gland scintigraphy. The impairment is worse in the parotid glands and increases with the total dose.

Among currently used cancer imaging methods, nuclear medicine modalities provide metabolic information, whereas modalities in radiology provide anatomical information. However, different modalities, having different acquisition times in separate machines, decrease the specificity and accuracy of images. To solve this problem, hybrid imaging modalities were developed as a new era, especially in the cancer imaging field. With widespread usage of hybrid imaging modalities, specific contrast agents are essentially needed to use in both modalities, such as single-photon emission computed tomography/computed tomography (SPECT/CT). Liposomes are one of the most desirable drug delivery systems, depending on their suitable properties. The aim of this study was to develop a liposomal contrast agent for the diagnosis and molecular imaging of tumor by SPECT/CT. Liposomes were prepared nanosized, coated with polyethylene glycol to obtain long blood circulation, and modified with monoclonal antibody 2C5 for specific tumor targeting. Although DTPA-PE and DTPA-PLL-NGPE (polychelating amphilic polymers; PAPs) were loaded onto liposomes for stable radiolabeling for SPECT imaging, iopromide was encapsulated into liposomes for CT imaging. Liposomes [(DPPC:PEG(2000)-PE:Chol:DTPA-PE), (PL 90G:PEG(2000)-PE:Chol:DTPA-PE), (DPPC:PEG(2000)-PE:Chol:PAPs), (PL 90G:PEG(2000)-PE:Chol:PAPs), (60:0.9:39:0.1% mol ratio)] were characterized in terms of entrapment efficiency, particle size, physical stability, and release kinetics. Additionally, in vitro cell-binding studies were carried out on two tumor cell lines (MCF-7 and EL 4) by counting radioactivity. Tumor-specific antibody-modified liposomes were found to be effective multimodal contrast agents by designating almost 3-8 fold more uptake than nonmodified ones in different tumor cell lines. These results could be considered as an important step in the development of tumor-targeted SPECT/CT contrast agents for cancer imaging.