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Purpose: Although, captopril scintigraphy is a well established method to detect renovascular hypertension, the optimal radiopharmaceutical for this test remains to be determined. Recently, Tc-99m ethylenedicysteine (Tc-99m EC) appeared as an alternative agent for captopril scintigraphy. The aim of this study was to compare the diagnostic accuracy of Tc-99m EC with Tc-99m DTPA, which is a well-established renal radiopharmaceutical for the captopril test., Methods: Nineteen hypertensive patients who had various degrees of renal artery stenosis on angiography were included in the study. All patients had baseline and captopril Tc-99m EC and Tc-99m DTPA scintigraphy within a 1-week period. The results were compared with angiography and in eight patients with changes in blood pressure after revascularization. The images were interpreted without knowledge of the angiography and revascularization data as low, intermediate, or high probability for hemodynamically significant renal artery stenosis, which was defined as an area of stenosis exceeding 50%., Results: Tc-99m EC and Tc-99m DTPA study results were in agreement in 16 of the 19 patients. In two patients with branch artery stenosis, Tc-99m EC was definitely superior to Tc-99m DTPA and correctly identified the probability of stenosis on scintigraphy. On kidney analysis, Tc-99m EC had a slightly greater diagnostic sensitivity compared with Tc-99m DTPA (79% vs. 68%; P > 0.05 by the chi-squared test) but equal specificity (93% for both agents). Both Tc-99m EC and Tc-99m DTPA showed the same accuracy in predicting the outcome after revascularization in all but one patient with branch artery stenosis, in whom Tc-99m EC accurately predicted a successful outcome of the intervention but Tc-99m DTPA did not. Tc-99m EC had better renal uptake in patients with decreased renal function and provided more dramatic evidence of renogram changes after captopril intervention, which resulted in more confident interpretation., Conclusions: There is no significant difference between Tc-99m EC and Tc-99m DTPA captopril scintigraphy for detecting renal artery stenosis. However, because of the better imaging characteristics and more confident interpretation provided by the dramatic changes in the degree of renogram abnormality after captopril intervention, Tc-99m EC captopril scintigraphy should be used, particularly in patients with decreased renal function or branch artery stenosis.

It is known that membrane folic acid receptors are responsible for cellular accumulation of folate and folate analogs such as methotrexate and overexpressed on various tumor cells. However, these receptors are highly restricted in normal differentiated tissues. Results of limited in vitro and in vivo animal studies suggest that folate receptors could be a potential target for tumor imaging. This study aimed to develop a 99mTc-labeled folic acid using ethylenedicysteine (EC) as a chelator and evaluate its labeling efficiency and potential use as a tumor seeking agent. Tissue distribution of 99mTc-EC-folate was determined in breast tumor-bearing rats at 20 min, 1, 2, and 4 h (n = 3/time interval, 370 KBq/rat, i.v.). Blocking study was employed to determine receptor-mediated process; 99mTc-EC-folate was co-administrated with 50 and 150 mumol/kg of cold folic acid to tumor-bearing rats. Planar imaging and whole-body autoradiograms were performed. The data was compared to that using 99mTc-EC (control). In animal studies, tumor/blood count density ratios at 20 min-4 h increased from 0.81 +/- 0.09 to 1.23 +/- 0.13 with 99mTc-EC-folate. Conversely, these values showed time-dependent decrease from 0.77 +/- 0.32 to 0.65 +/- 0.01 with 99mTc-EC in the same time period. Tumor/muscle and tumor/blood count density ratios significantly decreased with folic acid co-administrations. Planar images and autoradiograms confirmed that the tumors could be visualized clearly with 99mTc-EC-folate.

Radionuclide scanning with tumour-seeking agents such as pentavalent technetium-99m dimercaptosuccinic acid [99mTc(V)-DMSA], thallium-201 and technetium-99m sestamibi (MIBI) has been reported to be useful in the detection of medullary thyroid carcinoma (MTC). We undertook a study in 14 MTC patients to determine the comparative imaging potential of 201Tl, MIBI and 99mTc(V)-DMSA in the detection of recurrent or metastatic MTC. All patients underwent total thyroidectomy and had persistently elevated serum calcitonin levels after the surgery. Scintigraphic studies were carried out 20 min after the injection of 111 MBq of 201Tl or 555 MBq of MIBI and 2 h following the injection of 370 MBq of 99mTc(V)-DMSA. All scintigraphic findings were correlated with contemporaneous CT or MRI studies. CT, MRI and bone scans showed 42 (26 bone, 16 soft tissue) metastatic sites in 11 of the 14 patients. In the remaining three patients no lesions were detected during diagnostic evaluation. 99mTc(V)-DMSA showed all of the soft tissue metastases but could not show two bone lesions. On the other hand, MIBI imaging was false-negative in 22 (52%) sites and 201Tl was false-negative in 34 (80%) sites. Overall, lesion detection sensitivities for 99mTc(V)-DMSA, MIBI and 201Tl were 95%, 47% and 19% respectively. We conclude that 99mTc(V)-DMSA is clearly superior to MIBI and 201Tl in the follow-up of MTC patients.

Two patients with active tuberculosis confirmed by chest radiography and positive sputum smears were included in this study to determine whether a Tc-99m labeled agent, such as DMSA or citrate could localize such lesions in comparison to Ga-67 citrate. Both patients had Tc-99m (V) DMSA, Tc-99m citrate, and Ga-67 citrate scanning at 1-day to 5-day intervals. Both patients had positive scan findings with all three radiopharmaceuticals. However, the quality of Tc-99m (V) DMSA scans was superior to Tc-99m citrate, which showed faint uptake. Tc-99m (V) DMSA may be a better alternative to Ga-67 citrate in the assessment of the activity and extent of tuberculosis.

The use of 99mTechnetium dimercaptosuccinic acid (99mTc DMSA) scanning for the early diagnosis of upper urinary tract infections has been preferred for a few years. In this research we investigated the use of 99mTc DMSA scanning in the localization of renal parenchymal involvement in urinary tract infection. Twenty-four children presenting with first acute urinary tract infection were studied. Investigations included physical examination, white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), antibody-coated bacteria (ACB) and early 99mTc DMSA scanning. 99mTc DMSA scanning was taken as the gold standard method in determining renal parenchymal inflammation. According to the 99mTc DMSA scanning the sensitivity of clinical findings was 57.14%, WBC 23.80%, ESR 33.33%, CRP 14.28% and ACB 71.42% in the localization of urinary tract infection. We propose early 99mTc DMSA scanning performed around the time of infection as a good technique for localization of the level of infection in the urinary tract.

Tc-99m MIBI imaging was performed in 34 patients with histopathologically proven malignant tumors. The study was performed in two steps. In the first step, only Tc-99m MIBI imaging was performed (Group 1). In the second step, both Tc-99m MIBI and Tl-201 imaging were performed for comparison (Group 2). Seventeen patients were studied in each step. The size of the smallest primary tumor (breast cancer) was 15 x 10 mm, and that of the largest (lung cancer) was 145 x 130 mm. Of the 34 patients, 26 showed Tc-99m MIBI uptake at the tumor site. In Group 1, 12 patients showed Tc-99m MIBI tumor uptake, but no uptake was detected in five patients (squamous cell carcinoma of the esophagus, teratoma of the testis, nonHodgkin's lymphoma, and squamous cell carcinoma of the lung). In Group 2, 13 patients showed both Tc-99m MIBI and Tl-201 uptake at the tumor site, but one patient with breast cancer showed only Tc-99m MIBI uptake, and three patients showed no Tc-99m MIBI and Tl-201 uptake (embryonal cell carcinoma of the testis, hepatocellular carcinoma). The overall sensitivity of Tc-99m MIBI imaging was 76.4%. In Group 2, the sensitivity was 82.3% for Tc-99m MIBI and 76.4% for Tl-201. Our preliminary clinical experience suggests that Tc-99m MIBI can be helpful in localizing malignant tumors and that its sensitivity is slightly higher than Tl-201.

A patient with pulmonary actinomycosis who unexpectedly showed focal uptake of technetium-99m-hexakis-2-methoxy isobutyl isonitrile and thallium-201 is presented. The appearance of the lesion on the chest radiograph and x-ray CT scan resembled a mediastinal tumor. The diagnosis of pulmonary actinomycosis was achieved by histopathologic examination of the surgically removed mass.

The case of a patient with giant lymph node hyperplasia of the mediastinum who unexpectedly showed focal uptake of technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) is presented in this article. The patient was included in our research programme of tumor imaging with 99mTc-MIBI because the appearance of the mass on the chest radiogram and CT scan resembled a mediastinal tumour. Final diagnosis of giant lymph node hyperplasia was achieved through histopathological examination of the surgically removed lymph node.