Diagnostic Efficacy of Dynamic Radiothallium Uptake in Thyroid Nodules Determined by Computer-Assisted Scintigraphy

Abstract

Radiothallium (201TI) has been proposed as a tracer in nuclear medicine for the diagnosis of cold thyroid nodules. Its potassium-mimetic characteristics, like those of 131Cs, can provide information on its turnover in the thyroid nodules; this serves as a basis for the distinction between benign and malignant thyroid tumours. The author presents a study on the diagnostic efficacy of 201TI as a tracer for thyroid nodules with the aim of evaluating the dynamic uptake and the biodistribution of 201TI after intravenous injection of 555–740 kBq/kg. A quantitative analysis was made by continuous scanning of 201TI distribution during the first 20–30 min following thallium injection, with further surveys from 40 to 60 min or more when fixation in a nodule was demonstrated. The ratio between 201TI uptakes in the nodule and in healthy tissue (density index) was calculated and a multiparametric analysis of the corresponding activity/ time curves was performed. This study included 176 patients. Concordance between clinico-histological diagnosis and radio-isotopic findings was demonstrated in 102 out of 106 colloidocystic goitres, in 42 out of 48 benign nodules including thyroiditis, and in 21 out of 22 malignant tumours; a significant statistical difference in the density index between solid and cystic nodules, but no difference between benign and malignant nodules; and a different201 Tl dynamic behaviour in nodules of different nature, with a clear statistical difference in the thallium release between malignant nodular and healthy tissue (nodular disappearance index). This method can improve the diagnosis value of scintigraphy for thyroid nodules enhancing the sensitivty of the radioisotopic applications in comparison with other non-invasive techniques.

The Diagnostic Efficiency of Ultrasound Computer–Aided Diagnosis in Differentiating Thyroid Nodules: A Systematic Review and Narrative Synthesis

“…Of these, 285 papers were unrelated to thyroid ultrasound computer-aided diagnosis. Six studies were excluded based on wrong outcomes, with two focusing on computer-assisted scintigraphy [24,25] while the other four focused on quantitative elastography [26], computed-tomography [27], laser ablation [28], and sonographic localization of metastatic lymph nodes [29]. Because the scope of this review was limited to human populations with thyroid nodules, two studies were excluded with one being a mouse model study [30] and the other a human cell line study [31].…”

Evaluation of thyroid nodules with technetium‐99m MIBI and technetium‐99m pertechnetate

“…18 However, there is published evidence suggesting MIBI is not specific for thyroid malignancy, 6,7 although most workers have established the usefulness of whole-body MIBI scintigraphy in the follow-up of patients with metastatic thyroid cancer. [13][14][15][16][17] In this study, MIBI accumulation seemed to depend on the pathologic condition of the nodule, because all but two malignant lesions were positive on MIBI. The two malignant cases that where MIBI negative showed an intense uptake on the 20-minute images with continual washout on the 2-hour delayed images.…”

“…At present, there is no radiopharmaceutical with satisfactory specificity in the detection of thyroid malignancy. 12 Most workers have confirmed the usefulness of wholebody MIBI scintigraphy in the detection of metastases in thyroid cancer, [13][14][15][16][17] but the results of primary tumor imaging, especially in the differentiation between benign and malignant nodules, have been inconclusive. 18 The purpose of this work was twofold: first, to evaluate specificity of MIBI versus three-phase thyroid pertechnetate scan, and second, to assess whether the MIBI uptake is influenced by malignant thyroid nodules.…”

Scintigraphy in Thyroid Nodular Pathology

“…Это подтверждено соответствием клинико-гистологических и сцинтиграфических находок в 96,2% случаев коллоидно-кистозного зоба, 87,5% солидных доброкачественных узлов и 95,4% злокачественных опухолей. Авторы предположили, что метаболические калий-имитационные характеристики радиоталлия, конкурентное участие в «тиреоидном насосе» обусловливают его концентрацию в ткани ЩЖ и прямую корреляцию со степенью пролиферативной активности поражения [31].…”