Comparison of I-124 and I-131 Radiopharmacokinetics in Patients Who Have Well-differentiated Thyroid Cancer and Are Prepared With Recombinant Human TSH Injection (rhTSH)
试验速览
- 阶段
- 不适用
- 状态
- 终止
- 发起方
- 入组人数
- 21
- 试验地点
- 2
- 主要终点
- Compare the measurement of radioiodine uptake and clearance in suspected metastatic foci of well-differentiated thyroid cancer
研究概览
简要总结
This research study is to compare the radiopharmacokinetics of I-124 to the radiopharmacokinetics of I-131 in patients who have well-differentiated thyroid cancer after recombinant human thyroid-stimulating hormone (rhTSH) injection. I-131 is routinely used for imaging and dosimetry for patients with well-differentiated thyroid cancer. In this study, I-124 is administered orally in capsular form, and the radiopharmacokinetics of I-124 is compared with I-131. I-124 is another isotope of iodine, which is cyclotron-produced. I-124 has multiple advantages:
- Ideal Half-Life (4.2 days) for delayed imaging.
- High resolution tomographic imaging.
- Feasibility of quantitating lesion uptake.
- Potential of dosimetry for the planning of radioiodine therapy.
Voluntary patients will have I-124 dosimetry performed in addition to the I-131 dosimetry, which is planned as part of routine clinical care. I-124 dosimetry is composed of four parts: (1) two extra doses of injections of rhTSH, (2) the administration of I-124, (3) PET imaging, and (4) drawing blood samples.
Patients will receive two additional injections of rhTSH. This is similar to the procedure for I-131 dosimetry. Second, they will receive I-124. I-124 is similar to I-131 except I-124 decays in a different way to emit a positron so that the PET scanner can be used for imaging. I-124 is given in the form of one or several capsules, which are taken by mouth. This is also similar to I-131. Third, PET/CT imaging is done for approximately 30 minutes to one hour on five consecutive days. Radiation from PET/CT scan is far less than what they receive from a diagnostic CT scan. For the fourth part, a technologist will draw about 5 cc from the forearm on each of the five consecutive days. This is also similar to I-131.
Initially, all patients will be randomized to one of two study groups. The first group will have the I-131 dosimetry performed first followed by the I-124 dosimetry, and the second group will have the I-124 dosimetry performed first followed by the I-131 dosimetry.
The risk of this study is considered very low, and the potential benefits to the patient are considered very high.
详细描述
Radiopharmacokinetics and Dosimetric Calculations
A tracer dosage of either I-131 or I-124 is first administered to the patient, and the clearance is then followed for the specified period. In the classical approach, the blood is considered the critical organ which is irradiated either from the
- particles emitted from activity in the blood itself, or from the
- emissions originating from activity dispersed throughout the remainder of the body. Therefore only two compartments need to be monitored for radioactivity: (a) blood and (b) the whole body. Based on a classical dosimetry approach, the radiation dose to the whole blood in cGy (rads) per MBq I-131 is calculated.
The calculation of the area under these two curves is based on a mathematical fit to the data points using a multiple exponential function. Since the data collection is terminated after 4 days these curves must then be extrapolated to infinity. A very conservative estimate is employed by assuming that the clearance following the final measured data point is based simply on the physical decay. This ignores any biological clearance and results in an overestimation of the area of these tails and hence in the radiation dose per millicurie administered.
Each patient will have the following calculated.
研究设计
- 研究类型
- Interventional
- 分配方式
- Na
- 干预模型
- Single Group
- 主要目的
- Other
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •18 years or older
- •Well-differentiated thyroid carcinoma
- •Referred for I-131 dosimetry
- •Preparation with Recombinant Human TSH (rh TSH)
排除标准
- •< 18 years of age
- •Pregnancy or breast feeding
- •Inability to comply with instructions
- •Simultaneous participation or participation in any other research study within the last month
- •A body weight greater than 350 lbs
- •A creatinine > 1.5 mg/ml for males and 1.4 mg/ml for females
- •Preparation with thyroid hormone withdrawal(THW)
研究组 & 干预措施
Radiopharmacokinetics
1-2 mCi I-124 orally, once per day, twice total 0.9mg rhTSH intravenous injection, once per day, four total
After TSH stimulation with Recombinant human TSH (rhTSH) for 2 days, a dose of radioactive iodine 124 ( I-124) 1.7 mCi is administrated orally and PET imaging is done for 5 continuous days including the day of the dose administration. On each day, just before imaging, 5 ml of blood is drawn.
Patients will be randomized to either the sequence above (e.g. I-131 followed by I-124) or to the reverse sequence in which the I-124 is given first followed by the I-131. If I-124 is administered first and as long as the whole body retention is < 2% by the start of the second rhTSH stimulation, the I-124 will not interfere with the I-131.
干预措施: Radioactive Iodine 124 (Radiation)
结局指标
主要结局
Compare the measurement of radioiodine uptake and clearance in suspected metastatic foci of well-differentiated thyroid cancer
时间窗: 2 years
次要结局
未报告次要终点
研究者
Douglas Van Nostrand
Director, Nuclear Medicine Research
Medstar Health Research Institute