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99Tcm-latex particles (LP) is a newly developed radiopharmaceutical for the evaluation of the gastrointestinal (GI) tract. Following oral ingestion, it passes through the entire GI tract undissolved. The purpose of the present investigation was to introduce the clinical application of 99Tcm-LP. A group of 11 healthy volunteers was studied. Following a 12 h fast, the subjects were given 150 ml of water containing 37 MBq of 99Tcm-LP orally. Dynamic images up to 2 h were recorded to document temporal progression of radioactivity. Static images of the abdomen and whole body were taken at intervals. In normal subjects the tracer arrival times at the caecum and sigmoid colon were 3.2±0.9 and 11.2±3.2 h, respectively. The average t1/2value for gastric emptying, 50 colonie filling and small bowel transit time were found to be 21.6±5.6, 233±72 and 211±66.4 min, respectively. In conclusion, 99Tcm-LP has the potential of providing functional information of the GI tract.

Problems stemming from the withdrawal of TSH suppressing doses of T4 or T3 and false-negative studies associated with 131I scintigraphy have justified the search for other radionuclides in the follow-up of patients with well-differentiated thyroid carcinoma. Although 201Tl and 99Tcm-MIBI (MIBI) have been suggested as alternatives, their role in the detection of residual and recurrent disease has yet to be established. We therefore studied 36 patients who had undergone total or near total thyroidectomy for well-differentiated thyroid carcinoma to determine the imaging potential of 201Tl, MIBI and 131I in the detection of residual or recurrent disease. Eighteen of the 36 patients had undergone 131I ablation. Imaging was performed 20 min following the intravenous injection of 111 MBq 201Tl or 555 MBq MIBI, or 48 h after the oral ingestion of 185 MBq 131I. The overall concordance between the 201Tl, MIBI and 131I scans was 70. The concordance between thyroglobulin (TG) levels and the 131I scans was 78; that between the 201Tl and MIBI scans and TG levels was 83. Among the group of pre-ablative patients, there were six false-negative results with 201Tl and three false-negative results with MIBI. Among the post-ablation group, the 201Tl and MIBI scans were falsely negative in five patients. The 131I scans revealed all known residual or recurrent diseases. In conclusion, 201Tl, MIBI or TG levels should not be used in the place of 131I for the detection of residual or recurrent thyroid cancer. However, in patients who have not had their TSH suppressing doses of T4 or T3 withdrawn, the role of 201Tl and MIBI is debatable.